Re: [PATCH v10] i2c: Add drivers for the AMD PCIe MP2 I2C controller

[Shah, Nehal-bakulchandra]

On 11/27/2018 10:09 PM, Elie Morisse wrote:
> Hi Nehal-bakulchandra,
> 
>> There was intention behind to make two separate driver for pci and I2c.
> It has future usecase in our platforms and hence we made modular designed.
> So better to make it two separate driver.
> 
> I merged the two modules into one because of Bjorn Helgaas' concern that
> the platform driver only exists to extract information from the ACPI
> namespace.
> And that didn't really address it tbh.
> 
> Currently the minor advantages of having two drivers is that each
> bus/adapter on the MP2 has its entry in sysfs and can be individually
> (un-)bound, and less code duplication in the driver. Now if AMD plans to
> expand the platform driver, that would probably make more sense to keep two
> drivers and two modules.
> 

As discussed last time yes we have usecase so better to keep separate driver.

> If the Linux maintainers consent to it I can re-split the module into two.
> 
>> Another thing i would like to understand why _DEP method based hint is
> required, i didn't find need of it.
> 
> In case there is more than one MP2 PCI device present on the same system,
> how do you determine which PCI device is an AMDI0011 ACPI device related to?
> 
> I pasted the Yoga 530's DSDT here: https://paste.kde.org/pjobniftq
> The only available hints are the _DEP, method, and also perhaps the UID or
> _ADR:
> 
>        Device (I2CB)
>         {
>             Name (_HID, "AMDI0011")  // _HID: Hardware ID
>             Name (_UID, One)  // _UID: Unique ID
>             Name (_ADR, One)  // _ADR: Address
> //...
>             Name (_DEP, Package (0x01)  // _DEP: Dependencies
>             {
>                 ^PCI0.GP17.MP2C
>             })
> 
> If _DEP shouldn't be used, could _UID (or _ADR?) be assumed to refer to the
> MP2 device, in the order in which the PCI devices are enumerated? i.e
> 
> UID
> 0 -> first MP2 bus 0
> 1 -> first MP2 bus 1
> 2 -> second MP2 bus 0
> 3 -> second MP2 bus 1
> etc.
> 
> There's currently no such computer around with more than one MP2 PCI device
> at the moment, but does the documentation say something about this?
>
Yes as of now there is no future plan to have any additional MP2-I2C device.
>> Indeed PCI device owned by i2c-mp2 device so what is the need of moving
> DMA mapping to PCI driver?
> 
> Not sure if I understand correctly, the DMA buffer has to be owned by the
> PCI device, not by the platform device/I2C adapter :
> 
>   i2c_common->dma_addr = dma_map_single(&privdata->pci_dev->dev, ...);
> 
> That's why it seemed more natural to move the mapping into the PCI driver,
> and this was also the last occurrence of the platform driver accessing the
> pci_dev pointer. However if you plan to introduce non-PCI I2C controllers
> with the same split between small messages transferred through registers
> and large ones going through DMA then yes it'd make more sense to put it
> back in the platform driver. But is that really an issue for now?

Not issue now but as we want both drivers to be seperate then let the client
driver be owner.
> Btw I'll submit a v11 version of the patch which definitely fixes the
> timeouts on Lenovo Ideapad 530s soon (already fixed in
> https://github.com/Syniurge/i2c-amd-mp2).
> 
> Elie

Just received will have a look :) thanks for the same.

Nehal
> Le lun. 26 nov. 2018 Ã 15:52, Shah, Nehal-bakulchandra <
> Nehal-bakulchandra.Shah@xxxxxxx> a Ãcrit :
> 
>>
>> Hi Elie Morisse,
>>
>> On 11/14/2018 10:00 PM, Elie Morisse wrote:
>>> I2C communication takes place through iomapped registers, or through DMA
>>> for more than 32 bytes transfers.
>>>
>>> MP2 controllers have two separate buses, so may accommodate up to two I2C
>>> adapters. Those adapters are listed in the ACPI namespace with the
>>> "AMDI0011" HID, and probed by a platform driver.
>>>
>>> This is major rework of the patch submitted by Nehal-bakulchandra Shah
>> from
>>> AMD (https://patchwork.kernel.org/patch/10597369/).
>>>
>>> Most of the event handling of v3 was rewritten to make it work with more
>>> than one bus (e.g on Ryzen-based Lenovo Yoga 530), and this version
>>> contains many more improvements.
>>>
>>> Signed-off-by: Elie Morisse <syniurge@xxxxxxxxx>
>>> ---
>>> Changes since v1 (https://www.spinics.net/lists/linux-i2c/msg34650.html
>> ):
>>> -> Add fix for IOMMU
>>> -> Add depedency of ACPI
>>> -> Add locks to avoid the crash
>>>
>>> Changes since v2 (https://patchwork.ozlabs.org/patch/961270/):
>>>
>>> -> fix for review comments
>>> -> fix for more than 32 bytes write issue
>>>
>>> Changes since v3 (https://patchwork.kernel.org/patch/10597369/) by Elie
>> M.:
>>>
>>> -> support more than one bus/adapter
>>> -> support more than one slave per bus
>>> -> use the bus speed specified by the slaves declared in the DSDT
>> instead of
>>>    assuming speed == 400kbits/s
>>> -> instead of kzalloc'ing a buffer for every less than 32 bytes reads,
>> simply
>>>    use i2c_msg.buf
>>> -> fix buffer overreads/overflows when (<=32 bytes) message lengths
>> aren't a
>>>    multiple of 4 by using memcpy_fromio and memcpy_toio
>>> -> use streaming DMA mappings instead of allocating a coherent DMA
>> buffer for
>>>    every >32 bytes read/write
>>> -> properly check for timeouts during i2c_amd_xfer and increase it from
>> 50
>>>    jiffies to 250 msecs (which is more in line with other drivers)
>>> -> complete amd_i2c_dev.msg even if the device doesn't return a
>> xxx_success
>>>    event, instead of stalling i2c_amd_xfer
>>> -> removed the spinlock and mdelay during i2c_amd_pci_configure, I
>> didn't see
>>>    the point since it's already waiting for a i2c_busenable_complete
>> event
>>> -> add an adapter-specific mutex lock for i2c_amd_xfer, since we don't
>> want
>>>    parallel calls writing to AMD_C2P_MSG0 (or AMD_C2P_MSG1)
>>> -> add a global mutex lock for registers AMD_C2P_MSG2 to AMD_C2P_MSG9,
>> which
>>>    are shared across the two busses/adapters
>>> -> add MODULE_DEVICE_TABLE to automatically load i2c-amd-platdrv if the
>> DSDT
>>>    enumerates devices with the "AMDI0011" HID
>>> -> set maximum length of reads/writes to 4095 (event's length field is
>> 12 bits)
>>> -> basic PM support
>>> -> style corrections to match the kernel code style, and tried to reduce
>> code
>>>    duplication whenever possible
>>>
>>> Changes since v4 by Elie M.:
>>>
>>> -> fix missing typecast warning
>>> -> removed the duplicated entry in Kconfig
>>>
>>> Changes since v5 by Elie M.:
>>>
>>> -> move DMA mapping from the platform driver to the PCI driver
>>> -> attempt to find the platform device's PCI parent through the _DEP
>> ACPI method
>>>    (if not found take the first MP2 device registred in the
>> i2c-amd-pci-mp2
>>>    driver, like before)
>>> -> do not assume anymore that the PCI device is owned by the
>> i2c-amd-pci-mp2
>>>    driver
>>> -> address other review comments by Bjorn Helgaas (meant for v3)
>>>
>>> Changes since v6 by Elie M.:
>>>
>>> -> remove unnecessary memcpy from the DMA buffer during
>> i2c_amd_read_completion
>>>
>>> Changes since v7 by Elie M.:
>>>
>>> -> merge the two modules into one named i2c-amd-mp2, delete now useless
>> exports
>>> -> unlock the C2P mutex if i2c_amd_xfer_msg timeouts, to prevent
>> stalling the
>>>    MP2 controller if a slave doesn't respond to a read or write request
>>> -> unmap the DMA buffer before read/write_complete
>>> -> fix bus_disable commands handling (no more errors during module exit)
>>> -> prefer managed versions of pci_ and dev_ functions whenever possible
>>> -> increase adapter retries from 0 to 3
>>> -> reduce code duplication in debugfs functions
>>> -> address other review points by Bjorn Helgaas (except regarding the
>> _DEP
>>>    hint)
>>>
>>> Changes since v8 by Elie M.:
>>>
>>> -> remove mostly redundant amd_i2c_rw_config, refer to i2c_msg whenever
>>> possible
>>> -> use i2c_get_dma_safe_msg_buf and i2c_put_dma_safe_msg_buf
>>> -> defer probe() by the platform driver if no MP2 device has been probed
>>> yet by the PCI driver (which should address Bjorn Helgaas' concern while
>>> preserving the platform driver)
>>> -> if the interrupt following a command doesn't get handled after 250ms,
>>> zero AMD_P2C_MSG_INTEN to prevent the MP2 from stalling for a few more
>>> seconds (there seems to be an interrupt issue with older Zen microcodes,
>>> upgrade your amd microcode package if you experience timeouts)
>>> -> include AMD_P2C_MSG3 and fix typo in debugfs output
>>> -> cosmetic fixes, code reduction, and better comments
>>> -> add Nehal Shah and Shyam Sundar S K from AMD to the list of
>> maintainers
>>>
>>> Changes since v9 by Elie M.:
>>>
>>> -> remove the xfer_lock mutex which was redundant with
>> i2c_adapter.bus_lock
>>> -> platform device remove() fixes (protection against the very unlikely
>>> case that both the PCI and platform devices get detached manually and
>>> simultaneously)
>>> -> fix manually unbinding the PCI device and then rebinding, there was an
>>> interrupt that wouldn't get serviced and thus the line got disabled
>>> -> look for the MP2 device corresponding to an AMDI0011 ACPI device in
>>> every device enumerated by _DEP, not just the first one
>>> -> set i2c_adapter.nr to pdev->id and call i2c_add_numbered_adapter()
>>> -> add Documentation/i2c/busses/ entry
>>> -> minor enhancements
>>>
>>>  Documentation/i2c/busses/i2c-amd-mp2  |  24 +
>>>  MAINTAINERS                           |   8 +
>>>  drivers/i2c/busses/Kconfig            |  10 +
>>>  drivers/i2c/busses/Makefile           |   2 +
>>>  drivers/i2c/busses/i2c-amd-mp2-pci.c  | 688 ++++++++++++++++++++++++++
>>>  drivers/i2c/busses/i2c-amd-mp2-plat.c | 352 +++++++++++++
>>>  drivers/i2c/busses/i2c-amd-mp2.h      | 213 ++++++++
>>>  7 files changed, 1297 insertions(+)
>>>  create mode 100644 Documentation/i2c/busses/i2c-amd-mp2
>>>  create mode 100644 drivers/i2c/busses/i2c-amd-mp2-pci.c
>>>  create mode 100644 drivers/i2c/busses/i2c-amd-mp2-plat.c
>>>  create mode 100644 drivers/i2c/busses/i2c-amd-mp2.h
>>>
>>> diff --git a/Documentation/i2c/busses/i2c-amd-mp2
>> b/Documentation/i2c/busses/i2c-amd-mp2
>>> new file mode 100644
>>> index 000000000000..4b3d4b804413
>>> --- /dev/null
>>> +++ b/Documentation/i2c/busses/i2c-amd-mp2
>>> @@ -0,0 +1,24 @@
>>> +Kernel driver i2c-amd-mp2
>>> +
>>> +Supported adapters:
>>> +  * AMD MP2 PCIe interface
>>> +
>>> +Datasheet: not publicly available.
>>> +
>>> +Authors:
>>> +     Shyam Sundar S K <Shyam-sundar.S-k@xxxxxxx>
>>> +     Nehal Shah <nehal-bakulchandra.shah@xxxxxxx>
>>> +     Elie Morisse <syniurge@xxxxxxxxx>
>>> +
>>> +Description
>>> +-----------
>>> +
>>> +The MP2 is an ARM processor programmed as an I2C controller and
>> communicating
>>> +with the x86 host through PCI.
>>> +
>>> +If you see something like this:
>>> +
>>> +03:00.7 Non-VGA unclassified device: Advanced Micro Devices, Inc. [AMD]
>> Device
>>> +
>>  15e6
>>> +
>>> +in your 'lspci -v', then this driver is for your device.
>>> diff --git a/MAINTAINERS b/MAINTAINERS
>>> index 6ac000cc006d..99382f213b1c 100644
>>> --- a/MAINTAINERS
>>> +++ b/MAINTAINERS
>>> @@ -791,6 +791,14 @@ F:       drivers/gpu/drm/amd/include/vi_structs.h
>>>  F:   drivers/gpu/drm/amd/include/v9_structs.h
>>>  F:   include/uapi/linux/kfd_ioctl.h
>>>
>>> +AMD MP2 I2C DRIVER
>>> +M:   Elie Morisse <syniurge@xxxxxxxxx>
>>> +M:   Nehal Shah <nehal-bakulchandra.shah@xxxxxxx>
>>> +M:   Shyam Sundar S K <shyam-sundar.s-k@xxxxxxx>
>>> +L:   linux-i2c@xxxxxxxxxxxxxxx
>>> +S:   Maintained
>>> +F:   drivers/i2c/busses/i2c-amd-mp2*
>>> +
>>>  AMD POWERPLAY
>>>  M:   Rex Zhu <rex.zhu@xxxxxxx>
>>>  M:   Evan Quan <evan.quan@xxxxxxx>
>>> diff --git a/drivers/i2c/busses/Kconfig b/drivers/i2c/busses/Kconfig
>>> index 451d4ae50e66..70819245919e 100644
>>> --- a/drivers/i2c/busses/Kconfig
>>> +++ b/drivers/i2c/busses/Kconfig
>>> @@ -77,6 +77,16 @@ config I2C_AMD8111
>>>         This driver can also be built as a module.  If so, the module
>>>         will be called i2c-amd8111.
>>>
>>> +config I2C_AMD_MP2_PCI
>>> +     tristate "AMD MP2 PCIe I2C adapter"
>>> +     depends on PCI && ACPI
>>> +     help
>>> +       If you say yes to this option, support will be included for the
>> AMD
>>> +       MP2 PCIe I2C adapter.
>>> +
>>> +       This driver can also be built as a module.  If so, the module
>>> +       will be called i2c-amd-mp2.
>>> +
>>>  config I2C_HIX5HD2
>>>       tristate "Hix5hd2 high-speed I2C driver"
>>>       depends on ARCH_HISI || ARCH_HIX5HD2 || COMPILE_TEST
>>> diff --git a/drivers/i2c/busses/Makefile b/drivers/i2c/busses/Makefile
>>> index 18b26af82b1c..b036ffab0165 100644
>>> --- a/drivers/i2c/busses/Makefile
>>> +++ b/drivers/i2c/busses/Makefile
>>> @@ -32,6 +32,8 @@ obj-$(CONFIG_I2C_POWERMAC)  += i2c-powermac.o
>>>
>>>  # Embedded system I2C/SMBus host controller drivers
>>>  obj-$(CONFIG_I2C_ALTERA)     += i2c-altera.o
>>> +obj-$(CONFIG_I2C_AMD_MP2_PCI)        += i2c-amd-mp2.o
>>> +i2c-amd-mp2-objs := i2c-amd-mp2-pci.o i2c-amd-mp2-plat.o
>>>  obj-$(CONFIG_I2C_ASPEED)     += i2c-aspeed.o
>>>  obj-$(CONFIG_I2C_AT91)               += i2c-at91.o
>>>  obj-$(CONFIG_I2C_AU1550)     += i2c-au1550.o
>>> diff --git a/drivers/i2c/busses/i2c-amd-mp2-pci.c
>> b/drivers/i2c/busses/i2c-amd-mp2-pci.c
>>> new file mode 100644
>>> index 000000000000..7beb38a06e34
>>> --- /dev/null
>>> +++ b/drivers/i2c/busses/i2c-amd-mp2-pci.c
>>> @@ -0,0 +1,688 @@
>>> +// SPDX-License-Identifier: GPL-2.0 OR BSD-3-Clause
>>> +/*
>>> + * AMD MP2 PCIe communication driver
>>> + *
>>> + * Authors: Shyam Sundar S K <Shyam-sundar.S-k@xxxxxxx>
>>> + *          Elie Morisse <syniurge@xxxxxxxxx>
>>> + */
>>> +
>>> +#include <linux/debugfs.h>
>>> +#include <linux/dma-mapping.h>
>>> +#include <linux/interrupt.h>
>>> +#include <linux/module.h>
>>> +#include <linux/pci.h>
>>> +#include <linux/slab.h>
>>> +
>>> +#include "i2c-amd-mp2.h"
>>> +
>>> +#define DRIVER_NAME  "i2c_amd_mp2"
>>> +#define DRIVER_DESC  "AMD(R) PCI-E MP2 I2C Controller Driver"
>>> +#define DRIVER_VER   "1.0"
>>> +
>>> +#define write64 _write64
>>> +static inline void _write64(u64 val, void __iomem *mmio)
>>> +{
>>> +     writel(val, mmio);
>>> +     writel(val >> 32, mmio + sizeof(u32));
>>> +}
>>> +
>>> +#define read64 _read64
>>> +static inline u64 _read64(void __iomem *mmio)
>>> +{
>>> +     u64 low, high;
>>> +
>>> +     low = readl(mmio);
>>> +     high = readl(mmio + sizeof(u32));
>>> +     return low | (high << 32);
>>> +}
>>> +
>>> +static void amd_mp2_c2p_mutex_lock(struct amd_i2c_common *i2c_common)
>>> +{
>>> +     struct amd_mp2_dev *privdata = i2c_common->mp2_dev;
>>> +
>>> +     /* there is only one data mailbox for two i2c adapters */
>>> +     mutex_lock(&privdata->c2p_lock);
>>> +     privdata->c2p_lock_busid = i2c_common->bus_id;
>>> +}
>>> +
>>> +static void amd_mp2_c2p_mutex_unlock(struct amd_i2c_common *i2c_common)
>>> +{
>>> +     struct amd_mp2_dev *privdata = i2c_common->mp2_dev;
>>> +
>>> +     if (unlikely(privdata->c2p_lock_busid != i2c_common->bus_id)) {
>>> +             dev_warn(ndev_dev(privdata),
>>> +                      "bus %d attempting to unlock C2P locked by bus
>> %d\n",
>>> +                      i2c_common->bus_id, privdata->c2p_lock_busid);
>>> +             return;
>>> +     }
>>> +
>>> +     mutex_unlock(&privdata->c2p_lock);
>>> +}
>>> +
>>> +static int amd_mp2_cmd(struct amd_mp2_dev *privdata,
>>> +                    union i2c_cmd_base i2c_cmd_base)
>>> +{
>>> +     void __iomem *reg;
>>> +
>>> +     reg = privdata->mmio + ((i2c_cmd_base.s.bus_id == 1) ?
>>> +                             AMD_C2P_MSG1 : AMD_C2P_MSG0);
>>> +     writel(i2c_cmd_base.ul, reg);
>>> +
>>> +     return 0;
>>> +}
>>> +
>>> +int amd_mp2_connect(struct amd_i2c_common *i2c_common, bool enable)
>>> +{
>>> +     struct amd_mp2_dev *privdata = i2c_common->mp2_dev;
>>> +     union i2c_cmd_base i2c_cmd_base;
>>> +
>>> +     dev_dbg(ndev_dev(privdata), "%s id: %d\n", __func__,
>>> +             i2c_common->bus_id);
>>> +
>>> +     i2c_common->reqcmd = enable ? i2c_enable : i2c_disable;
>>> +
>>> +     i2c_cmd_base.ul = 0;
>>> +     i2c_cmd_base.s.i2c_cmd = i2c_common->reqcmd;
>>> +     i2c_cmd_base.s.bus_id = i2c_common->bus_id;
>>> +     i2c_cmd_base.s.i2c_speed = i2c_common->i2c_speed;
>>> +
>>> +     return amd_mp2_cmd(privdata, i2c_cmd_base);
>>> +}
>>> +
>>> +static void amd_mp2_cmd_rw_fill(struct amd_i2c_common *i2c_common,
>>> +                             union i2c_cmd_base *i2c_cmd_base,
>>> +                             enum i2c_cmd reqcmd)
>>> +{
>>> +     i2c_common->reqcmd = reqcmd;
>>> +
>>> +     i2c_cmd_base->s.i2c_cmd = reqcmd;
>>> +     i2c_cmd_base->s.bus_id = i2c_common->bus_id;
>>> +     i2c_cmd_base->s.i2c_speed = i2c_common->i2c_speed;
>>> +     i2c_cmd_base->s.slave_addr = i2c_common->msg->addr;
>>> +     i2c_cmd_base->s.length = i2c_common->msg->len;
>>> +}
>>> +
>>> +static int amd_mp2_dma_map(struct amd_mp2_dev *privdata,
>>> +                        struct amd_i2c_common *i2c_common)
>>> +{
>>> +     enum dma_data_direction dma_direction =
>>> +                     i2c_common->msg->flags & I2C_M_RD ?
>>> +                     DMA_FROM_DEVICE : DMA_TO_DEVICE;
>>> +
>>> +     i2c_common->dma_buf = i2c_get_dma_safe_msg_buf(i2c_common->msg, 0);
>>> +     i2c_common->dma_addr = dma_map_single(&privdata->pci_dev->dev,
>>> +                                           i2c_common->dma_buf,
>>> +                                           i2c_common->msg->len,
>>> +                                           dma_direction);
>>> +
>>> +     if (dma_mapping_error(&privdata->pci_dev->dev,
>>> +                           i2c_common->dma_addr)) {
>>> +             dev_err(ndev_dev(privdata),
>>> +                     "Error while mapping dma buffer %p\n",
>>> +                     i2c_common->dma_buf);
>>> +             return -EIO;
>>> +     }
>>> +
>>> +     return 0;
>>> +}
>>> +
>>> +static void amd_mp2_dma_unmap(struct amd_mp2_dev *privdata,
>>> +                           struct amd_i2c_common *i2c_common)
>>> +{
>>> +     enum dma_data_direction dma_direction =
>>> +                     i2c_common->msg->flags & I2C_M_RD ?
>>> +                     DMA_FROM_DEVICE : DMA_TO_DEVICE;
>>> +
>>> +     dma_unmap_single(&privdata->pci_dev->dev,
>>> +                      i2c_common->dma_addr,
>>> +                      i2c_common->msg->len,
>>> +                      dma_direction);
>>> +
>>> +     i2c_put_dma_safe_msg_buf(i2c_common->dma_buf, i2c_common->msg,
>> true);
>>> +}
>>> +
>>> +int amd_mp2_read(struct amd_i2c_common *i2c_common)
>>> +{
>>> +     struct amd_mp2_dev *privdata = i2c_common->mp2_dev;
>>> +     union i2c_cmd_base i2c_cmd_base;
>>> +
>>> +     dev_dbg(ndev_dev(privdata), "%s addr: %x id: %d\n", __func__,
>>> +             i2c_common->msg->addr, i2c_common->bus_id);
>>> +
>>> +     amd_mp2_cmd_rw_fill(i2c_common, &i2c_cmd_base, i2c_read);
>>> +     amd_mp2_c2p_mutex_lock(i2c_common);
>>> +
>>> +     if (i2c_common->msg->len <= 32) {
>>> +             i2c_cmd_base.s.mem_type = use_c2pmsg;
>>> +     } else {
>>> +             i2c_cmd_base.s.mem_type = use_dram;
>>> +             if (amd_mp2_dma_map(privdata, i2c_common))
>>> +                     return -EIO;
>>> +             write64((u64)i2c_common->dma_addr,
>>> +                     privdata->mmio + AMD_C2P_MSG2);
>>> +     }
>>> +
>>> +     return amd_mp2_cmd(privdata, i2c_cmd_base);
>>> +}
>>> +
>>> +int amd_mp2_write(struct amd_i2c_common *i2c_common)
>>> +{
>>> +     struct amd_mp2_dev *privdata = i2c_common->mp2_dev;
>>> +     union i2c_cmd_base i2c_cmd_base;
>>> +
>>> +     dev_dbg(ndev_dev(privdata), "%s addr: %x id: %d\n", __func__,
>>> +             i2c_common->msg->addr, i2c_common->bus_id);
>>> +
>>> +     amd_mp2_cmd_rw_fill(i2c_common, &i2c_cmd_base, i2c_write);
>>> +     amd_mp2_c2p_mutex_lock(i2c_common);
>>> +
>>> +     if (i2c_common->msg->len <= 32) {
>>> +             i2c_cmd_base.s.mem_type = use_c2pmsg;
>>> +             memcpy_toio(privdata->mmio + AMD_C2P_MSG2,
>>> +                         i2c_common->msg->buf,
>>> +                         i2c_common->msg->len);
>>> +     } else {
>>> +             i2c_cmd_base.s.mem_type = use_dram;
>>> +             if (amd_mp2_dma_map(privdata, i2c_common))
>>> +                     return -EIO;
>>> +             write64((u64)i2c_common->dma_addr,
>>> +                     privdata->mmio + AMD_C2P_MSG2);
>>> +     }
>>> +
>>> +     return amd_mp2_cmd(privdata, i2c_cmd_base);
>>> +}
>>> +
>>> +static void amd_mp2_pci_check_rw_event(struct amd_i2c_common
>> *i2c_common)
>>> +{
>>> +     struct amd_mp2_dev *privdata = i2c_common->mp2_dev;
>>> +     int len = i2c_common->eventval.r.length;
>>> +     u32 slave_addr = i2c_common->eventval.r.slave_addr;
>>> +
>>> +     if (len != i2c_common->msg->len)
>>> +             dev_err(ndev_dev(privdata),
>>> +                     "length %d in event doesn't match buffer length
>> %d!\n",
>>> +                     len, i2c_common->msg->len);
>>> +     if (slave_addr != i2c_common->msg->addr)
>>> +             dev_err(ndev_dev(privdata),
>>> +                     "unexpected slave address %x (expected: %x)!\n",
>>> +                     slave_addr, i2c_common->msg->addr);
>>> +}
>>> +
>>> +static void amd_mp2_pci_do_work(struct work_struct *work)
>>> +{
>>> +     struct amd_i2c_common *i2c_common = work_amd_i2c_common(work);
>>> +     struct amd_mp2_dev *privdata = i2c_common->mp2_dev;
>>> +     int sts = i2c_common->eventval.r.status;
>>> +     int res = i2c_common->eventval.r.response;
>>> +     int len = i2c_common->eventval.r.length;
>>> +
>>> +     if ((i2c_common->reqcmd == i2c_read ||
>>> +          i2c_common->reqcmd == i2c_write) &&
>>> +         i2c_common->msg->len > 32)
>>> +             amd_mp2_dma_unmap(privdata, i2c_common);
>>> +
>>> +     if (res != command_success) {
>>> +             if (res == command_failed)
>>> +                     dev_err(ndev_dev(privdata), "i2c command
>> failed!\n");
>>> +             else
>>> +                     dev_err(ndev_dev(privdata), "invalid response to
>> i2c command!\n");
>>> +             i2c_amd_msg_completion(i2c_common);
>>> +             return;
>>> +     }
>>> +
>>> +     switch (i2c_common->reqcmd) {
>>> +     case i2c_read:
>>> +             if (sts == i2c_readcomplete_event) {
>>> +                     amd_mp2_pci_check_rw_event(i2c_common);
>>> +                     if (len <= 32)
>>> +                             memcpy_fromio(i2c_common->msg->buf,
>>> +                                           privdata->mmio +
>> AMD_C2P_MSG2,
>>> +                                           i2c_common->msg->len);
>>> +             } else if (sts == i2c_readfail_event) {
>>> +                     dev_err(ndev_dev(privdata), "i2c read failed!\n");
>>> +             } else {
>>> +                     dev_err(ndev_dev(privdata),
>>> +                             "invalid i2c status after read (%d)!\n",
>> sts);
>>> +             }
>>> +             break;
>>> +     case i2c_write:
>>> +             if (sts == i2c_writecomplete_event)
>>> +                     amd_mp2_pci_check_rw_event(i2c_common);
>>> +             else if (sts == i2c_writefail_event)
>>> +                     dev_err(ndev_dev(privdata), "i2c write failed!\n");
>>> +             else
>>> +                     dev_err(ndev_dev(privdata),
>>> +                             "invalid i2c status after write (%d)!\n",
>> sts);
>>> +             break;
>>> +     case i2c_enable:
>>> +             if (sts == i2c_busenable_failed)
>>> +                     dev_err(ndev_dev(privdata), "i2c bus enable
>> failed!\n");
>>> +             else if (sts != i2c_busenable_complete)
>>> +                     dev_err(ndev_dev(privdata),
>>> +                             "invalid i2c status after bus enable
>> (%d)!\n",
>>> +                             sts);
>>> +             break;
>>> +     case i2c_disable:
>>> +             if (sts == i2c_busdisable_failed)
>>> +                     dev_err(ndev_dev(privdata), "i2c bus disable
>> failed!\n");
>>> +             else if (sts != i2c_busdisable_complete)
>>> +                     dev_err(ndev_dev(privdata),
>>> +                             "invalid i2c status after bus disable
>> (%d)!\n",
>>> +                             sts);
>>> +             break;
>>> +     default:
>>> +             break;
>>> +     }
>>> +
>>> +     i2c_amd_msg_completion(i2c_common);
>>> +}
>>> +
>>> +static void amd_mp2_pci_work(struct work_struct *work)
>>> +{
>>> +     struct amd_i2c_common *i2c_common = work_amd_i2c_common(work);
>>> +     struct amd_mp2_dev *privdata = i2c_common->mp2_dev;
>>> +     enum i2c_cmd cmd = i2c_common->reqcmd;
>>> +
>>> +     amd_mp2_pci_do_work(work);
>>> +
>>> +     i2c_common->reqcmd = i2c_none;
>>> +
>>> +     if (cmd == i2c_read || cmd == i2c_write)
>>> +             mutex_unlock(&privdata->c2p_lock);
>>> +}
>>> +
>>> +static irqreturn_t amd_mp2_irq_isr(int irq, void *dev)
>>> +{
>>> +     struct amd_mp2_dev *privdata = dev;
>>> +     struct amd_i2c_common *i2c_common;
>>> +     u32 val;
>>> +     unsigned int bus_id;
>>> +     void __iomem *reg;
>>> +     unsigned long flags;
>>> +     enum irqreturn ret = IRQ_NONE;
>>> +
>>> +     raw_spin_lock_irqsave(&privdata->lock, flags);
>>> +
>>> +     for (bus_id = 0; bus_id < 2; bus_id++) {
>>> +             i2c_common = privdata->busses[bus_id];
>>> +             if (!i2c_common)
>>> +                     continue;
>>> +
>>> +             reg = privdata->mmio + ((bus_id == 0) ?
>>> +                                     AMD_P2C_MSG1 : AMD_P2C_MSG2);
>>> +             val = readl(reg);
>>> +             if (val != 0) {
>>> +                     i2c_common->eventval.ul = val;
>>> +
>>> +                     writel(0, reg);
>>> +                     writel(0, privdata->mmio + AMD_P2C_MSG_INTEN);
>>> +
>>> +                     if (i2c_common->reqcmd != i2c_none)
>>> +                             schedule_delayed_work(&i2c_common->work,
>> 0);
>>> +
>>> +                     ret = IRQ_HANDLED;
>>> +             }
>>> +     }
>>> +
>>> +     raw_spin_unlock_irqrestore(&privdata->lock, flags);
>>> +     return ret;
>>> +}
>>> +
>>> +void amd_mp2_rw_timeout(struct amd_i2c_common *i2c_common)
>>> +{
>>> +     struct amd_mp2_dev *privdata = i2c_common->mp2_dev;
>>> +
>>> +     writel(0, privdata->mmio + AMD_P2C_MSG_INTEN);
>>> +     amd_mp2_c2p_mutex_unlock(i2c_common);
>>> +}
>>> +
>>> +int amd_mp2_register_cb(struct amd_i2c_common *i2c_common)
>>> +{
>>> +     struct amd_mp2_dev *privdata = i2c_common->mp2_dev;
>>> +
>>> +     if (i2c_common->bus_id > 1)
>>> +             return -EINVAL;
>>> +
>>> +     if (privdata->busses[i2c_common->bus_id]) {
>>> +             dev_err(ndev_dev(privdata),
>>> +                     "Bus %d already taken!\n", i2c_common->bus_id);
>>> +             return -EINVAL;
>>> +     }
>>> +
>>> +     privdata->busses[i2c_common->bus_id] = i2c_common;
>>> +     i2c_common->reqcmd = i2c_none;
>>> +     INIT_DELAYED_WORK(&i2c_common->work, amd_mp2_pci_work);
>>> +
>>> +     return 0;
>>> +}
>>> +
>>> +int amd_mp2_unregister_cb(struct amd_i2c_common *i2c_common)
>>> +{
>>> +     struct amd_mp2_dev *privdata = i2c_common->mp2_dev;
>>> +
>>> +     cancel_delayed_work_sync(&i2c_common->work);
>>> +     privdata->busses[i2c_common->bus_id] = NULL;
>>> +
>>> +     return 0;
>>> +}
>>> +
>>> +#ifdef CONFIG_DEBUG_FS
>>> +static const struct file_operations amd_mp2_debugfs_info;
>>> +static struct dentry *debugfs_root_dir;
>>> +
>>> +static ssize_t amd_mp2_debugfs_read(struct file *filp, char __user
>> *ubuf,
>>> +                                 size_t count, loff_t *offp)
>>> +{
>>> +     struct amd_mp2_dev *privdata;
>>> +     void __iomem *mmio;
>>> +     u8 *buf;
>>> +     size_t buf_size;
>>> +     ssize_t ret, off = 0;
>>> +     u32 v32;
>>> +     int i;
>>> +
>>> +     privdata = filp->private_data;
>>> +     mmio = privdata->mmio;
>>> +     buf_size = min_t(size_t, count, 0x800);
>>> +     buf = kmalloc(buf_size, GFP_KERNEL);
>>> +
>>> +     if (!buf)
>>> +             return -ENOMEM;
>>> +
>>> +     off += scnprintf(buf + off, buf_size - off,
>>> +                      "MP2 Device Information:\n");
>>> +
>>> +     off += scnprintf(buf + off, buf_size - off,
>>> +                      "========================\n");
>>> +     off += scnprintf(buf + off, buf_size - off,
>>> +                      "\tMP2 C2P Message Register Dump:\n\n");
>>> +
>>> +     for (i = 0; i < 10; i++) {
>>> +             v32 = readl(privdata->mmio + AMD_C2P_MSG0 + i * 4);
>>> +             off += scnprintf(buf + off, buf_size - off,
>>> +                              "AMD_C2P_MSG%d -\t\t\t%#06x\n", i, v32);
>>> +     }
>>> +
>>> +     off += scnprintf(buf + off, buf_size - off,
>>> +                     "\n\tMP2 P2C Message Register Dump:\n\n");
>>> +
>>> +     for (i = 0; i < 3; i++) {
>>> +             v32 = readl(privdata->mmio + AMD_P2C_MSG1 + i * 4);
>>> +             off += scnprintf(buf + off, buf_size - off,
>>> +                              "AMD_P2C_MSG%d -\t\t\t%#06x\n", i + 1,
>> v32);
>>> +     }
>>> +
>>> +     v32 = readl(privdata->mmio + AMD_P2C_MSG_INTEN);
>>> +     off += scnprintf(buf + off, buf_size - off,
>>> +                     "AMD_P2C_MSG_INTEN -\t\t%#06x\n", v32);
>>> +
>>> +     v32 = readl(privdata->mmio + AMD_P2C_MSG_INTSTS);
>>> +     off += scnprintf(buf + off, buf_size - off,
>>> +                     "AMD_P2C_MSG_INTSTS -\t\t%#06x\n", v32);
>>> +
>>> +     ret = simple_read_from_buffer(ubuf, count, offp, buf, off);
>>> +     kfree(buf);
>>> +     return ret;
>>> +}
>>> +
>>> +static const struct file_operations amd_mp2_debugfs_info = {
>>> +     .owner = THIS_MODULE,
>>> +     .open = simple_open,
>>> +     .read = amd_mp2_debugfs_read,
>>> +};
>>> +
>>> +static void amd_mp2_init_debugfs(struct amd_mp2_dev *privdata)
>>> +{
>>> +     if (!debugfs_root_dir)
>>> +             return;
>>> +
>>> +     privdata->debugfs_dir = debugfs_create_dir(ndev_name(privdata),
>>> +                                                debugfs_root_dir);
>>> +     if (!privdata->debugfs_dir) {
>>> +             privdata->debugfs_info = NULL;
>>> +     } else {
>>> +             privdata->debugfs_info = debugfs_create_file
>>> +                     ("info", 0400, privdata->debugfs_dir,
>>> +                      privdata, &amd_mp2_debugfs_info);
>>> +     }
>>> +}
>>> +#endif /* CONFIG_DEBUG_FS */
>>> +
>>> +static void amd_mp2_clear_reg(struct amd_mp2_dev *privdata)
>>> +{
>>> +     int reg;
>>> +
>>> +     for (reg = AMD_C2P_MSG0; reg <= AMD_C2P_MSG9; reg += 4)
>>> +             writel(0, privdata->mmio + reg);
>>> +
>>> +     for (reg = AMD_P2C_MSG1; reg <= AMD_P2C_MSG2; reg += 4)
>>> +             writel(0, privdata->mmio + reg);
>>> +}
>>> +
>>> +static int amd_mp2_pci_init(struct amd_mp2_dev *privdata,
>>> +                         struct pci_dev *pci_dev)
>>> +{
>>> +     int rc;
>>> +
>>> +     pci_set_drvdata(pci_dev, privdata);
>>> +
>>> +     rc = pcim_enable_device(pci_dev);
>>> +     if (rc) {
>>> +             dev_err(ndev_dev(privdata), "Failed to enable MP2 PCI
>> device\n");
>>> +             goto err_pci_enable;
>>> +     }
>>> +
>>> +     rc = pcim_iomap_regions(pci_dev, 1 << 2, pci_name(pci_dev));
>>> +     if (rc) {
>>> +             dev_err(ndev_dev(privdata), "I/O memory remapping
>> failed\n");
>>> +             goto err_pci_enable;
>>> +     }
>>> +     privdata->mmio = pcim_iomap_table(pci_dev)[2];
>>> +
>>> +     pci_set_master(pci_dev);
>>> +
>>> +     rc = pci_set_dma_mask(pci_dev, DMA_BIT_MASK(64));
>>> +     if (rc) {
>>> +             rc = pci_set_dma_mask(pci_dev, DMA_BIT_MASK(32));
>>> +             if (rc)
>>> +                     goto err_dma_mask;
>>> +     }
>>> +
>>> +     /* Set up intx irq */
>>> +     writel(0, privdata->mmio + AMD_P2C_MSG_INTEN);
>>> +     raw_spin_lock_init(&privdata->lock);
>>> +     pci_intx(pci_dev, 1);
>>> +     rc = devm_request_irq(&pci_dev->dev, pci_dev->irq, amd_mp2_irq_isr,
>>> +                           IRQF_SHARED, dev_name(&pci_dev->dev),
>> privdata);
>>> +     if (rc)
>>> +             dev_err(&pci_dev->dev, "Failure requesting irq %i: %d\n",
>>> +                     pci_dev->irq, rc);
>>> +
>>> +     return rc;
>>> +
>>> +err_dma_mask:
>>> +     pci_clear_master(pci_dev);
>>> +err_pci_enable:
>>> +     pci_set_drvdata(pci_dev, NULL);
>>> +     return rc;
>>> +}
>>> +
>>> +static int amd_mp2_pci_probe(struct pci_dev *pci_dev,
>>> +                          const struct pci_device_id *id)
>>> +{
>>> +     struct amd_mp2_dev *privdata;
>>> +     int rc;
>>> +     static bool first_probe = true;
>>> +
>>> +     if (first_probe) {
>>> +             pr_info("%s: %s Version: %s\n", DRIVER_NAME,
>>> +                     DRIVER_DESC, DRIVER_VER);
>>> +             first_probe = false;
>>> +     }
>>> +
>>> +     dev_info(&pci_dev->dev, "MP2 device found [%04x:%04x] (rev %x)\n",
>>> +              pci_dev->vendor, pci_dev->device, pci_dev->revision);
>>> +
>>> +     privdata = devm_kzalloc(&pci_dev->dev, sizeof(*privdata),
>> GFP_KERNEL);
>>> +     if (!privdata)
>>> +             return -ENOMEM;
>>> +
>>> +     rc = amd_mp2_pci_init(privdata, pci_dev);
>>> +     if (rc)
>>> +             return rc;
>>> +
>>> +     mutex_init(&privdata->c2p_lock);
>>> +     privdata->pci_dev = pci_dev;
>>> +
>>> +     amd_mp2_init_debugfs(privdata);
>>> +     dev_info(&pci_dev->dev, "MP2 device registered.\n");
>>> +     return 0;
>>> +}
>>> +
>>> +static bool amd_mp2_pci_is_probed(struct pci_dev *pci_dev)
>>> +{
>>> +     struct amd_mp2_dev *privdata = pci_get_drvdata(pci_dev);
>>> +
>>> +     if (!privdata)
>>> +             return false;
>>> +     return privdata->pci_dev != NULL;
>>> +}
>>> +
>>> +static void amd_mp2_pci_remove(struct pci_dev *pci_dev)
>>> +{
>>> +     struct amd_mp2_dev *privdata = pci_get_drvdata(pci_dev);
>>> +     unsigned int bus_id;
>>> +
>>> +     for (bus_id = 0; bus_id < 2; bus_id++)
>>> +             if (privdata->busses[bus_id])
>>> +                     i2c_amd_delete_adapter(privdata->busses[bus_id]);
>>> +
>>> +#ifdef CONFIG_DEBUG_FS
>>> +     debugfs_remove_recursive(privdata->debugfs_dir);
>>> +#endif /* CONFIG_DEBUG_FS */
>>> +
>>> +     pci_intx(pci_dev, 0);
>>> +     pci_clear_master(pci_dev);
>>> +
>>> +     amd_mp2_clear_reg(privdata);
>>> +}
>>> +
>>> +static const struct pci_device_id amd_mp2_pci_tbl[] = {
>>> +     {PCI_VDEVICE(AMD, PCI_DEVICE_ID_AMD_MP2)},
>>> +     {0}
>>> +};
>>> +MODULE_DEVICE_TABLE(pci, amd_mp2_pci_tbl);
>>> +
>>> +#ifdef CONFIG_PM_SLEEP
>>> +static int amd_mp2_pci_device_suspend(struct pci_dev *pci_dev,
>>> +                                   pm_message_t mesg)
>>> +{
>>> +     int ret;
>>> +     struct amd_mp2_dev *privdata = pci_get_drvdata(pci_dev);
>>> +
>>> +     if (!privdata)
>>> +             return -EINVAL;
>>> +
>>> +     ret = pci_save_state(pci_dev);
>>> +     if (ret) {
>>> +             dev_err(ndev_dev(privdata),
>>> +                     "pci_save_state failed = %d\n", ret);
>>> +             return ret;
>>> +     }
>>> +
>>> +     pci_enable_wake(pci_dev, PCI_D3hot, 0);
>>> +     pci_disable_device(pci_dev);
>>> +     pci_set_power_state(pci_dev, pci_choose_state(pci_dev, mesg));
>>> +
>>> +     return 0;
>>> +}
>>> +
>>> +static int amd_mp2_pci_device_resume(struct pci_dev *pci_dev)
>>> +{
>>> +     struct amd_mp2_dev *privdata = pci_get_drvdata(pci_dev);
>>> +
>>> +     if (!privdata)
>>> +             return -EINVAL;
>>> +
>>> +     pci_set_power_state(pci_dev, PCI_D0);
>>> +     pci_restore_state(pci_dev);
>>> +
>>> +     if (pci_enable_device(pci_dev) < 0) {
>>> +             dev_err(ndev_dev(privdata), "pci_enable_device failed\n");
>>> +             return -EIO;
>>> +     }
>>> +
>>> +     pci_enable_wake(pci_dev, PCI_D3hot, 0);
>>> +
>>> +     return 0;
>>> +}
>>> +#endif
>>> +
>>> +static struct pci_driver amd_mp2_pci_driver = {
>>> +     .name           = DRIVER_NAME,
>>> +     .id_table       = amd_mp2_pci_tbl,
>>> +     .probe          = amd_mp2_pci_probe,
>>> +     .remove         = amd_mp2_pci_remove,
>>> +#ifdef CONFIG_PM_SLEEP
>>> +     .suspend        = amd_mp2_pci_device_suspend,
>>> +     .resume         = amd_mp2_pci_device_resume,
>>> +#endif
>>> +};
>>> +
>>> +static int amd_mp2_device_match(struct device *dev, void *data)
>>> +{
>>> +     struct pci_dev *candidate = data;
>>> +
>>> +     if (!candidate)
>>> +             return 1;
>>> +     return (to_pci_dev(dev) == candidate) ? 1 : 0;
>>> +}
>>> +
>>> +struct amd_mp2_dev *amd_mp2_find_device(struct pci_dev *candidate)
>>> +{
>>> +     struct device *dev;
>>> +     struct pci_dev *pci_dev;
>>> +
>>> +     dev = driver_find_device(&amd_mp2_pci_driver.driver, NULL,
>> candidate,
>>> +                              amd_mp2_device_match);
>>> +     if (!dev)
>>> +             return NULL;
>>> +
>>> +     pci_dev = to_pci_dev(dev);
>>> +     if (!amd_mp2_pci_is_probed(pci_dev))
>>> +             return NULL;
>>> +     return (struct amd_mp2_dev *)pci_get_drvdata(pci_dev);
>>> +}
>>> +
>>> +static int __init amd_mp2_drv_init(void)
>>> +{
>>> +     int rc;
>>> +
>>> +#ifdef CONFIG_DEBUG_FS
>>> +     debugfs_root_dir = debugfs_create_dir(KBUILD_MODNAME, NULL);
>>> +#endif /* CONFIG_DEBUG_FS */
>>> +
>>> +     rc = pci_register_driver(&amd_mp2_pci_driver);
>>> +     if (rc)
>>> +             return rc;
>>> +     return i2c_amd_register_driver();
>>> +}
>>> +module_init(amd_mp2_drv_init);
>>> +
>>> +static void __exit amd_mp2_drv_exit(void)
>>> +{
>>> +     i2c_amd_unregister_driver();
>>> +     pci_unregister_driver(&amd_mp2_pci_driver);
>>> +
>>> +#ifdef CONFIG_DEBUG_FS
>>> +     debugfs_remove_recursive(debugfs_root_dir);
>>> +#endif /* CONFIG_DEBUG_FS */
>>> +}
>>> +module_exit(amd_mp2_drv_exit);
>>> +
>>> +MODULE_DESCRIPTION(DRIVER_DESC);
>>> +MODULE_VERSION(DRIVER_VER);
>>> +MODULE_AUTHOR("Shyam Sundar S K <Shyam-sundar.S-k@xxxxxxx>");
>>> +MODULE_AUTHOR("Nehal Shah <nehal-bakulchandra.shah@xxxxxxx>");
>>> +MODULE_AUTHOR("Elie Morisse <syniurge@xxxxxxxxx>");
>>> +MODULE_LICENSE("Dual BSD/GPL");
>>> diff --git a/drivers/i2c/busses/i2c-amd-mp2-plat.c
>> b/drivers/i2c/busses/i2c-amd-mp2-plat.c
>>> new file mode 100644
>>> index 000000000000..e9687850cf32
>>> --- /dev/null
>>> +++ b/drivers/i2c/busses/i2c-amd-mp2-plat.c
>>> @@ -0,0 +1,352 @@
>>> +// SPDX-License-Identifier: GPL-2.0 OR BSD-3-Clause
>>> +/*
>>> + * AMD MP2 platform driver
>>> + *
>>> + * Setup the I2C adapters enumerated in the ACPI namespace.
>>> + * MP2 controllers have 2 separate buses, i.e up to 2 I2C adapters.
>>> + *
>>> + * Authors: Nehal Bakulchandra Shah <Nehal-bakulchandra.shah@xxxxxxx>
>>> + *          Elie Morisse <syniurge@xxxxxxxxx>
>>> + */
>>> +
>>> +#include <linux/acpi.h>
>>> +#include <linux/kernel.h>
>>> +#include <linux/module.h>
>>> +#include <linux/platform_device.h>
>>> +#include <linux/slab.h>
>>> +#include <linux/types.h>
>>> +
>>> +#include "i2c-amd-mp2.h"
>>> +
>>> +#define AMD_MP2_I2C_MAX_RW_LENGTH ((1 << 12) - 1)
>>> +#define AMD_I2C_TIMEOUT (msecs_to_jiffies(250))
>>> +
>>> +/**
>>> + * struct amd_i2c_dev - MP2 bus/i2c adapter context
>>> + * @i2c_common: shared context with the MP2 PCI driver
>>> + * @pdev: platform driver node
>>> + * @adapter: i2c adapter
>>> + * @completion: xfer completion object
>>> + */
>>> +struct amd_i2c_dev {
>>> +     struct amd_i2c_common i2c_common;
>>> +     struct platform_device *pdev;
>>> +     struct i2c_adapter adapter;
>>> +     struct completion msg_complete;
>>> +     bool is_connected;
>>> +};
>>> +
>>> +#define amd_i2c_dev_common(__common) \
>>> +     container_of(__common, struct amd_i2c_dev, i2c_common)
>>> +
>>> +void i2c_amd_msg_completion(struct amd_i2c_common *i2c_common)
>>> +{
>>> +     struct amd_i2c_dev *i2c_dev = amd_i2c_dev_common(i2c_common);
>>> +     union i2c_event *event = &i2c_common->eventval;
>>> +
>>> +     if (event->r.status == i2c_readcomplete_event)
>>> +             dev_dbg(&i2c_dev->pdev->dev, "%s readdata:%*ph\n",
>>> +                     __func__, event->r.length,
>>> +                     i2c_common->msg->buf);
>>> +
>>> +     complete(&i2c_dev->msg_complete);
>>> +}
>>> +
>>> +static int i2c_amd_pci_xconnect(struct amd_i2c_dev *i2c_dev, bool
>> enable)
>>> +{
>>> +     struct amd_i2c_common *i2c_common = &i2c_dev->i2c_common;
>>> +     unsigned long timeout;
>>> +
>>> +     reinit_completion(&i2c_dev->msg_complete);
>>> +
>>> +     amd_mp2_connect(i2c_common, enable);
>>> +     timeout = wait_for_completion_timeout(&i2c_dev->msg_complete,
>>> +                                           AMD_I2C_TIMEOUT);
>>> +     if (timeout == 0) {
>>> +             dev_err(&i2c_dev->pdev->dev,
>>> +                     "i2c connection timed out\n");
>>> +             return -ETIMEDOUT;
>>> +     }
>>> +
>>> +     return 0;
>>> +}
>>> +
>>> +static int i2c_amd_xfer_msg(struct amd_i2c_dev *i2c_dev, struct i2c_msg
>> *pmsg)
>>> +{
>>> +     struct amd_i2c_common *i2c_common = &i2c_dev->i2c_common;
>>> +     unsigned long timeout;
>>> +     bool is_read = pmsg->flags & I2C_M_RD;
>>> +
>>> +     reinit_completion(&i2c_dev->msg_complete);
>>> +
>>> +     i2c_common->msg = pmsg;
>>> +
>>> +     if (is_read)
>>> +             amd_mp2_read(i2c_common);
>>> +     else
>>> +             amd_mp2_write(i2c_common);
>>> +
>>> +     timeout = wait_for_completion_timeout(&i2c_dev->msg_complete,
>>> +                                           AMD_I2C_TIMEOUT);
>>> +     if (timeout == 0) {
>>> +             dev_err(&i2c_dev->pdev->dev, "i2c %s timed out\n",
>>> +                     is_read ? "read" : "write");
>>> +             amd_mp2_rw_timeout(i2c_common);
>>> +             return -ETIMEDOUT;
>>> +     }
>>> +
>>> +     return 0;
>>> +}
>>> +
>>> +static int i2c_amd_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
>> int num)
>>> +{
>>> +     struct amd_i2c_dev *i2c_dev = i2c_get_adapdata(adap);
>>> +     int i;
>>> +     struct i2c_msg *pmsg;
>>> +     int err;
>>> +
>>> +     if (unlikely(!i2c_dev->is_connected)) {
>>> +             i2c_amd_pci_xconnect(i2c_dev, true);
>>> +             i2c_dev->is_connected = 1;
>>> +     }
>>> +
>>> +     for (i = 0; i < num; i++) {
>>> +             pmsg = &msgs[i];
>>> +             err = i2c_amd_xfer_msg(i2c_dev, pmsg);
>>> +             if (err)
>>> +                     break;
>>> +     }
>>> +
>>> +     if (err)
>>> +             return err;
>>> +     return num;
>>> +}
>>> +
>>> +static u32 i2c_amd_func(struct i2c_adapter *a)
>>> +{
>>> +     return I2C_FUNC_I2C;
>>> +}
>>> +
>>> +static const struct i2c_algorithm i2c_amd_algorithm = {
>>> +     .master_xfer = i2c_amd_xfer,
>>> +     .functionality = i2c_amd_func,
>>> +};
>>> +
>>> +static enum speed_enum i2c_amd_get_bus_speed(struct platform_device
>> *pdev)
>>> +{
>>> +     u32 acpi_speed;
>>> +     int i;
>>> +     static const u32 supported_speeds[] = {
>>> +             0, 100000, 400000, 1000000, 1400000, 3400000
>>> +     };
>>> +
>>> +     acpi_speed = i2c_acpi_find_bus_speed(&pdev->dev);
>>> +     /* round down to the lowest standard speed */
>>> +     for (i = 1; i < ARRAY_SIZE(supported_speeds); i++) {
>>> +             if (acpi_speed < supported_speeds[i])
>>> +                     break;
>>> +     }
>>> +     acpi_speed = supported_speeds[i - 1];
>>> +
>>> +     switch (acpi_speed) {
>>> +     case 100000:
>>> +             return speed100k;
>>> +     case 400000:
>>> +             return speed400k;
>>> +     case 1000000:
>>> +             return speed1000k;
>>> +     case 1400000:
>>> +             return speed1400k;
>>> +     case 3400000:
>>> +             return speed3400k;
>>> +     default:
>>> +             return speed400k;
>>> +     }
>>> +}
>>> +
>>> +static struct device *i2c_amd_acpi_get_first_phys_node(struct
>> acpi_device *adev)
>>> +{
>>> +     const struct acpi_device_physical_node *node;
>>> +
>>> +     if (list_empty(&adev->physical_node_list))
>>> +             return NULL;
>>> +
>>> +     node = list_first_entry(&adev->physical_node_list,
>>> +                             struct acpi_device_physical_node, node);
>>> +     return node->dev;
>>> +}
>>> +
>>> +/*
>>> + * On Lenovo Ideapad/Yoga the _DEP ACPI method appears to be the only
>> available
>>> + * hint at which PCI device an AMDI0011 ACPI device corresponds to.
>>> + * i2c_amd_find_mp2_hint goes through the PCI devices enumerated by the
>> _DEP
>>> + * method and select the first listed MP2 device.
>>> + */
>>> +static struct amd_mp2_dev *i2c_amd_find_mp2_hint(struct acpi_device
>> *adev)
>>> +{
>>> +     struct acpi_handle_list dep_devices;
>>> +     acpi_status status;
>>> +     struct amd_mp2_dev *mp2_dev = NULL;
>>> +     int i;
>>> +
>>> +     if (!acpi_has_method(adev->handle, "_DEP"))
>>> +             return NULL;
>>> +
>>> +     status = acpi_evaluate_reference(adev->handle, "_DEP", NULL,
>>> +                                      &dep_devices);
>>> +     if (ACPI_FAILURE(status))
>>> +             return NULL;
>>> +
>>> +     for (i = 0; i < dep_devices.count; i++) {
>>> +             struct acpi_device *dep_adev;
>>> +             struct device *dep_phys_dev;
>>> +             struct pci_dev *pci_candidate;
>>> +
>>> +             if (acpi_bus_get_device(dep_devices.handles[i], &dep_adev))
>>> +                     continue;
>>> +             dep_phys_dev = i2c_amd_acpi_get_first_phys_node(dep_adev);
>>> +
>>> +             if (!dep_phys_dev || !dev_is_pci(dep_phys_dev))
>>> +                     continue;
>>> +             pci_candidate = to_pci_dev(dep_phys_dev);
>>> +
>>> +             mp2_dev = amd_mp2_find_device(pci_candidate);
>>> +             if (mp2_dev)
>>> +                     break;
>>> +     }
>>> +
>>> +     return mp2_dev;
>>> +}
>>> +
>>> +static const struct i2c_adapter_quirks amd_i2c_dev_quirks = {
>>> +     .max_read_len = AMD_MP2_I2C_MAX_RW_LENGTH,
>>> +     .max_write_len = AMD_MP2_I2C_MAX_RW_LENGTH,
>>> +};
>>> +
>>> +static int i2c_amd_probe(struct platform_device *pdev)
>>> +{
>>> +     int ret;
>>> +     struct amd_i2c_dev *i2c_dev;
>>> +     acpi_handle handle = ACPI_HANDLE(&pdev->dev);
>>> +     struct acpi_device *adev;
>>> +     struct amd_mp2_dev *mp2_dev;
>>> +     const char *uid;
>>> +
>>> +     if (acpi_bus_get_device(handle, &adev))
>>> +             return -ENODEV;
>>> +
>>> +     mp2_dev = i2c_amd_find_mp2_hint(adev);
>>> +     if (!mp2_dev)
>>> +             /* If the hint pointed at a PCI device which isn't a MP2,
>> go
>>> +              * for the first MP2 device registered in the PCI driver
>>> +              */
>>> +             mp2_dev = amd_mp2_find_device(NULL);
>>> +     if (!mp2_dev)
>>> +             /* The corresponding MP2 PCI device might get probed later
>> */
>>> +             return -EPROBE_DEFER;
>>> +
>>> +     i2c_dev = devm_kzalloc(&pdev->dev, sizeof(*i2c_dev), GFP_KERNEL);
>>> +     if (!i2c_dev)
>>> +             return -ENOMEM;
>>> +
>>> +     i2c_dev->i2c_common.mp2_dev = mp2_dev;
>>> +     i2c_dev->pdev = pdev;
>>> +     platform_set_drvdata(pdev, i2c_dev);
>>> +
>>> +     uid = adev->pnp.unique_id;
>>> +     if (!uid) {
>>> +             dev_err(&pdev->dev, "missing UID/bus id!\n");
>>> +             return -EINVAL;
>>> +     } else if (strcmp(uid, "0") == 0) {
>>> +             i2c_dev->i2c_common.bus_id = 0;
>>> +     } else if (strcmp(uid, "1") == 0) {
>>> +             i2c_dev->i2c_common.bus_id = 1;
>>> +     } else {
>>> +             dev_err(&pdev->dev, "incorrect UID/bus id \"%s\"!\n", uid);
>>> +             return -EINVAL;
>>> +     }
>>> +     dev_dbg(&pdev->dev, "bus id is %u\n", i2c_dev->i2c_common.bus_id);
>>> +
>>> +     if (amd_mp2_register_cb(&i2c_dev->i2c_common))
>>> +             return -EINVAL;
>>> +
>>> +     i2c_dev->i2c_common.i2c_speed = i2c_amd_get_bus_speed(pdev);
>>> +
>>> +     /* setup i2c adapter description */
>>> +     i2c_dev->adapter.owner = THIS_MODULE;
>>> +     i2c_dev->adapter.algo = &i2c_amd_algorithm;
>>> +     i2c_dev->adapter.quirks = &amd_i2c_dev_quirks;
>>> +     i2c_dev->adapter.dev.parent = &pdev->dev;
>>> +     i2c_dev->adapter.algo_data = i2c_dev;
>>> +     i2c_dev->adapter.nr = pdev->id;
>>> +     ACPI_COMPANION_SET(&i2c_dev->adapter.dev,
>> ACPI_COMPANION(&pdev->dev));
>>> +     i2c_dev->adapter.dev.of_node = pdev->dev.of_node;
>>> +     snprintf(i2c_dev->adapter.name, sizeof(i2c_dev->adapter.name),
>>> +              "AMD MP2 i2c bus %u", i2c_dev->i2c_common.bus_id);
>>> +     i2c_set_adapdata(&i2c_dev->adapter, i2c_dev);
>>> +
>>> +     init_completion(&i2c_dev->msg_complete);
>>> +
>>> +     /* and finally attach to the i2c layer */
>>> +     ret = i2c_add_numbered_adapter(&i2c_dev->adapter);
>>> +
>>> +     if (ret < 0)
>>> +             dev_err(&pdev->dev, "i2c add adapter failed = %d\n", ret);
>>> +
>>> +     return ret;
>>> +}
>>> +
>>> +void i2c_amd_delete_adapter(struct amd_i2c_common *i2c_common)
>>> +{
>>> +     struct amd_i2c_dev *i2c_dev = amd_i2c_dev_common(i2c_common);
>>> +
>>> +     i2c_lock_bus(&i2c_dev->adapter, I2C_LOCK_ROOT_ADAPTER);
>>> +     if (!i2c_common->mp2_dev) {
>>> +             i2c_unlock_bus(&i2c_dev->adapter, I2C_LOCK_ROOT_ADAPTER);
>>> +             return;
>>> +     }
>>> +
>>> +     if (i2c_dev->is_connected)
>>> +             i2c_amd_pci_xconnect(i2c_dev, false);
>>> +
>>> +     amd_mp2_unregister_cb(i2c_common);
>>> +
>>> +     i2c_common->mp2_dev = NULL;
>>> +     i2c_unlock_bus(&i2c_dev->adapter, I2C_LOCK_ROOT_ADAPTER);
>>> +     i2c_del_adapter(&i2c_dev->adapter);
>>> +}
>>> +
>>> +static int i2c_amd_remove(struct platform_device *pdev)
>>> +{
>>> +     struct amd_i2c_dev *i2c_dev = platform_get_drvdata(pdev);
>>> +     struct amd_i2c_common *i2c_common = &i2c_dev->i2c_common;
>>> +
>>> +     i2c_amd_delete_adapter(i2c_common);
>>> +
>>> +     return 0;
>>> +}
>>> +
>>> +static const struct acpi_device_id i2c_amd_acpi_match[] = {
>>> +     { "AMDI0011" },
>>> +     { },
>>> +};
>>> +MODULE_DEVICE_TABLE(acpi, i2c_amd_acpi_match);
>>> +
>>> +static struct platform_driver i2c_amd_plat_driver = {
>>> +     .probe = i2c_amd_probe,
>>> +     .remove = i2c_amd_remove,
>>> +     .driver = {
>>> +             .name = "i2c_amd_mp2",
>>> +             .acpi_match_table = ACPI_PTR(i2c_amd_acpi_match),
>>> +     },
>>> +};
>>> +
>>> +int i2c_amd_register_driver(void)
>>> +{
>>> +     return platform_driver_register(&i2c_amd_plat_driver);
>>> +}
>>> +
>>> +void i2c_amd_unregister_driver(void)
>>> +{
>>> +     platform_driver_unregister(&i2c_amd_plat_driver);
>>> +}
>>> diff --git a/drivers/i2c/busses/i2c-amd-mp2.h
>> b/drivers/i2c/busses/i2c-amd-mp2.h
>>> new file mode 100644
>>> index 000000000000..883c8d211ed0
>>> --- /dev/null
>>> +++ b/drivers/i2c/busses/i2c-amd-mp2.h
>>> @@ -0,0 +1,213 @@
>>> +/* SPDX-License-Identifier: GPL-2.0 OR BSD-3-Clause */
>>> +/*
>>> + * AMD MP2 I2C adapter driver
>>> + *
>>> + * Authors: Shyam Sundar S K <Shyam-sundar.S-k@xxxxxxx>
>>> + *          Elie Morisse <syniurge@xxxxxxxxx>
>>> + */
>>> +
>>> +#ifndef I2C_AMD_PCI_MP2_H
>>> +#define I2C_AMD_PCI_MP2_H
>>> +
>>> +#include <linux/i2c.h>
>>> +#include <linux/pci.h>
>>> +
>>> +#define PCI_DEVICE_ID_AMD_MP2        0x15E6
>>> +
>>> +struct amd_i2c_common;
>>> +struct amd_mp2_dev;
>>> +
>>> +enum {
>>> +     /* MP2 C2P Message Registers */
>>> +     AMD_C2P_MSG0 = 0x10500,                 /* MP2 Message for I2C0 */
>>> +     AMD_C2P_MSG1 = 0x10504,                 /* MP2 Message for I2C1 */
>>> +     AMD_C2P_MSG2 = 0x10508,                 /* DRAM Address Lo / Data
>> 0 */
>>> +     AMD_C2P_MSG3 = 0x1050c,                 /* DRAM Address HI / Data
>> 1 */
>>> +     AMD_C2P_MSG4 = 0x10510,                 /* Data 2 */
>>> +     AMD_C2P_MSG5 = 0x10514,                 /* Data 3 */
>>> +     AMD_C2P_MSG6 = 0x10518,                 /* Data 4 */
>>> +     AMD_C2P_MSG7 = 0x1051c,                 /* Data 5 */
>>> +     AMD_C2P_MSG8 = 0x10520,                 /* Data 6 */
>>> +     AMD_C2P_MSG9 = 0x10524,                 /* Data 7 */
>>> +
>>> +     /* MP2 P2C Message Registers */
>>> +     AMD_P2C_MSG0 = 0x10680,                 /* Do not use */
>>> +     AMD_P2C_MSG1 = 0x10684,                 /* I2C0 interrupt register
>> */
>>> +     AMD_P2C_MSG2 = 0x10688,                 /* I2C1 interrupt register
>> */
>>> +     AMD_P2C_MSG3 = 0x1068C,                 /* MP2 debug info */
>>> +     AMD_P2C_MSG_INTEN = 0x10690,            /* MP2 interrupt gen
>> register */
>>> +     AMD_P2C_MSG_INTSTS = 0x10694,           /* Interrupt status */
>>> +};
>>> +
>>> +/* Command register data structures */
>>> +
>>> +#define i2c_none (-1)
>>> +enum i2c_cmd {
>>> +     i2c_read = 0,
>>> +     i2c_write,
>>> +     i2c_enable,
>>> +     i2c_disable,
>>> +     number_of_sensor_discovered,
>>> +     is_mp2_active,
>>> +     invalid_cmd = 0xF,
>>> +};
>>> +
>>> +enum speed_enum {
>>> +     speed100k = 0,
>>> +     speed400k = 1,
>>> +     speed1000k = 2,
>>> +     speed1400k = 3,
>>> +     speed3400k = 4
>>> +};
>>> +
>>> +enum mem_type {
>>> +     use_dram = 0,
>>> +     use_c2pmsg = 1,
>>> +};
>>> +
>>> +/**
>>> + * union i2c_cmd_base : bit access of C2P commands
>>> + * @i2c_cmd: bit 0..3 i2c R/W command
>>> + * @bus_id: bit 4..7 i2c bus index
>>> + * @slave_addr: bit 8..15 slave address
>>> + * @length: bit 16..27 read/write length
>>> + * @i2c_speed: bit 28..30 bus speed
>>> + * @mem_type: bit 31 0-DRAM; 1-C2P msg o/p
>>> + */
>>> +union i2c_cmd_base {
>>> +     u32 ul;
>>> +     struct {
>>> +             enum i2c_cmd i2c_cmd : 4;
>>> +             u8 bus_id : 4;
>>> +             u32 slave_addr : 8;
>>> +             u32 length : 12;
>>> +             enum speed_enum i2c_speed : 3;
>>> +             enum mem_type mem_type : 1;
>>> +     } s;
>>> +};
>>> +
>>> +/* Response - Response of SFI */
>>> +enum response_type {
>>> +     invalid_response = 0,
>>> +     command_success = 1,
>>> +     command_failed = 2,
>>> +};
>>> +
>>> +/* Status - Command ID to indicate a command */
>>> +enum status_type {
>>> +     i2c_readcomplete_event = 0,
>>> +     i2c_readfail_event = 1,
>>> +     i2c_writecomplete_event = 2,
>>> +     i2c_writefail_event = 3,
>>> +     i2c_busenable_complete = 4,
>>> +     i2c_busenable_failed = 5,
>>> +     i2c_busdisable_complete = 6,
>>> +     i2c_busdisable_failed = 7,
>>> +     invalid_data_length = 8,
>>> +     invalid_slave_address = 9,
>>> +     invalid_i2cbus_id = 10,
>>> +     invalid_dram_addr = 11,
>>> +     invalid_command = 12,
>>> +     mp2_active = 13,
>>> +     numberof_sensors_discovered_resp = 14,
>>> +     i2c_bus_notinitialized
>>> +};
>>> +
>>> +/**
>>> + * union i2c_event : bit access of P2C events
>>> + * @response: bit 0..1 i2c response type
>>> + * @status: bit 2..6 status_type
>>> + * @mem_type: bit 7 0-DRAM; 1-C2P msg o/p
>>> + * @bus_id: bit 8..11 i2c bus id
>>> + * @length: bit 12..23 message length
>>> + * @slave_addr: bit 24-31 slave address
>>> + */
>>> +union i2c_event {
>>> +     u32 ul;
>>> +     struct {
>>> +             enum response_type response : 2;
>>> +             enum status_type status : 5;
>>> +             enum mem_type mem_type : 1;
>>> +             u8 bus_id : 4;
>>> +             u32 length : 12;
>>> +             u32 slave_addr : 8;
>>> +     } r;
>>> +};
>>> +
>>> +/**
>>> + * struct amd_i2c_common - per bus/i2c adapter context, shared
>>> + *   between the pci and the platform driver
>>> + * @eventval: MP2 event value set by the IRQ handler to be processed
>>> + *         by the worker
>>> + * @msg: i2c message
>>> + * @work: delayed worker struct
>>> + * @reqcmd: requested i2c command type
>>> + * @bus_id: bus index
>>> + * @i2c_speed: i2c bus speed determined by the slowest slave
>>> + * @dma_addr: if length > 32, holds the DMA buffer address
>>> + * @dma_direction: if length > 32, is either FROM or TO device
>>> + */
>>> +struct amd_i2c_common {
>>> +     union i2c_event eventval;
>>> +     struct amd_mp2_dev *mp2_dev;
>>> +     struct i2c_msg *msg;
>>> +     struct delayed_work work;
>>> +     enum i2c_cmd reqcmd;
>>> +     u8 bus_id;
>>> +     enum speed_enum i2c_speed;
>>> +     u8 *dma_buf;
>>> +     dma_addr_t dma_addr;
>>> +};
>>> +
>>> +/**
>>> + * struct amd_mp2_dev - per PCI device context
>>> + * @pci_dev: PCI driver node
>>> + * @busses: MP2 devices may have up to two busses,
>>> + *       each bus corresponding to an i2c adapter
>>> + * @mmio: iommapped registers
>>> + * @lock: interrupt spinlock
>>> + * @c2p_lock: controls access to the C2P mailbox shared between
>>> + *         the two adapters
>>> + * @c2p_lock_busid: id of the adapter which locked c2p_lock
>>> + */
>>> +struct amd_mp2_dev {
>>> +     struct pci_dev *pci_dev;
>>> +     struct amd_i2c_common *busses[2];
>>> +     void __iomem *mmio;
>>> +     raw_spinlock_t lock;
>>> +     struct mutex c2p_lock;
>>> +     u8 c2p_lock_busid;
>>> +#ifdef CONFIG_DEBUG_FS
>>> +     struct dentry *debugfs_dir;
>>> +     struct dentry *debugfs_info;
>>> +#endif /* CONFIG_DEBUG_FS */
>>> +};
>>> +
>>> +#define ndev_pdev(ndev) ((ndev)->pci_dev)
>>> +#define ndev_name(ndev) pci_name(ndev_pdev(ndev))
>>> +#define ndev_dev(ndev) (&ndev_pdev(ndev)->dev)
>>> +#define work_amd_i2c_common(__work) \
>>> +     container_of(__work, struct amd_i2c_common, work.work)
>>> +
>>> +/* PCIe communication driver */
>>> +
>>> +int amd_mp2_read(struct amd_i2c_common *i2c_common);
>>> +int amd_mp2_write(struct amd_i2c_common *i2c_common);
>>> +int amd_mp2_connect(struct amd_i2c_common *i2c_common, bool enable);
>>> +
>>> +void amd_mp2_rw_timeout(struct amd_i2c_common *i2c_common);
>>> +
>>> +int amd_mp2_register_cb(struct amd_i2c_common *i2c_common);
>>> +int amd_mp2_unregister_cb(struct amd_i2c_common *i2c_common);
>>> +
>>> +struct amd_mp2_dev *amd_mp2_find_device(struct pci_dev *candidate);
>>> +
>>> +/* Platform driver */
>>> +
>>> +void i2c_amd_msg_completion(struct amd_i2c_common *i2c_common);
>>> +void i2c_amd_delete_adapter(struct amd_i2c_common *i2c_common);
>>> +
>>> +int i2c_amd_register_driver(void);
>>> +void i2c_amd_unregister_driver(void);
>>> +
>>> +#endif
>>>
>>
>> Thanks for your contribution in making this driver more stable and adding
>> support for multiple device. I could validate on Yoga 530 platform and it
>> worked
>> without any problem. There was intention behind to make two separate
>> driver for pci and I2c. It has future usecase in our platforms and hence we
>> made modular designed. So better to make it two separate driver. Another
>> thing i would like to understand why _DEP method based hint is required, i
>> didn't find need of it.
>> Indeed PCI device owned by i2c-mp2 device so what is the need of moving
>> DMA mapping to PCI driver?
>>
>> Thanks
>> Nehal Shah
>>
>