Re: [patch v6 1/1] i2c: add master driver for mellanox systems
From: Peter Rosin
Date: Thu Nov 17 2016 - 03:05:59 EST
Hi!
Some comments inline.
Cheers,
Peter
On 2016-11-17 09:30, vadimp@xxxxxxxxxxxx wrote:
> From: Vadim Pasternak <vadimp@xxxxxxxxxxxx>
>
> Device driver for Mellanox I2C controller logic, implemented in Lattice
> CPLD device.
> Device supports:
> - Master mode
> - One physical bus
> - Polling mode
>
> The Kconfig currently controlling compilation of this code is:
> drivers/i2c/busses/Kconfig:config I2C_MLXCPLD
>
> Signed-off-by: Michael Shych <michaelsh@xxxxxxxxxxxx>
> Signed-off-by: Vadim Pasternak <vadimp@xxxxxxxxxxxx>
> Reviewed-by: Jiri Pirko <jiri@xxxxxxxxxxxx>
> Reviewed-by: Vladimir Zapolskiy <vz@xxxxxxxxx>
> ---
> v5->v6:
> Comments pointed out by Vladimir:
> - Drop the line with module path from the header;
> - In description of mlxcpld_i2c_priv remove lpc_gen_dec_reg asnd dev_id;
> - In mlxcpld_i2c_priv change type of the filed base_addr to u16 for
> the alignment with in/out and remove unused dev_id;
> - Fix misspelling in comment for mlxcpld_i2c_invalid_len;
> - Remove comment regarding EBUSY return in mlxcpld_i2c_check_busy;
> - Use sizeof of the target storage in allocation in probe routine;
> v4->v5:
> Comments pointed out by Vladimir:
> - Remove "default n" from Kconfig;
> - Fix the comments for timeout and pool time;
> - Optimize error flow in mlxcpld_i2c_probe;
> v3->v4:
> Comments pointed out by Vladimir:
> - Set default to no in Kconfig;
> - Make mlxcpld_i2c_plat_dev static and add empty line before the
> declaration;
> - In function mlxcpld_i2c_invalid_len remove (msg->len < 0), since len is
> unsigned;
> - Remove unused symbol mlxcpld_i2c_plat_dev;
> - Remove extra spaces in comments to mlxcpld_i2c_check_msg_params;
> - Remove unnecessary round braces in mlxcpld_i2c_set_transf_data;
> - Remove the assignment of 'i' variable in mlxcpld_i2c_wait_for_tc;
> - Add extra line in mlxcpld_i2c_xfer;
> - Move assignment of the adapter's fields retries and nr inside
> mlxcpld_i2c_adapter declaration;
> v2->v3:
> Comments pointed out by Vladimir:
> - Use tab symbol as indentation in Kconfig
> - Add the Kconfig section preserving the alphabetical order - added
> within "Other I2C/SMBus bus drivers" after I2C_ELEKTOR (but after this
> sections others are not follow alphabetical);
> - Change license to dual;
> - Replace ADRR with ADDR in macros;
> - Remove unused macros: MLXCPLD_LPCI2C_LPF_DFLT,
> MLXCPLD_LPCI2C_HALF_CYC_100, MLXCPLD_LPCI2C_I2C_HOLD_100,
> MLXCPLD_LPCI2C_HALF_CYC_REG, MLXCPLD_LPCI2C_I2C_HOLD_REG;
> - Fix checkpatch warnings (**/ and the end of comment);
> - Add empty line before structures mlxcpld_i2c_regs,
> mlxcpld_i2c_curr_transf, mlxcpld_i2c_priv;
> - Remove unused structure mlxcpld_i2c_regs;
> - Remove from mlxcpld_i2c_priv the next fields:
> retr_num, poll_time, block_sz, xfer_to; use instead macros
> respectively: MLXCPLD_I2C_RETR_NUM, MLXCPLD_I2C_POLL_TIME,
> MLXCPLD_I2C_DATA_REG_SZ, MLXCPLD_I2C_XFER_TO;
> - In mlxcpld_i2c_invalid_len remove unnecessary else;
> - Optimize mlxcpld_i2c_set_transf_data;
> - mlxcpld_i2c_reset - add empty lines after/before mutex
> lock/unlock;
> - mlxcpld_i2c_wait_for_free - cover case timeout is equal
> MLXCPLD_I2C_XFER_TO;
> - mlxcpld_i2c_wait_for_tc:
> - Do not assign err in declaration (also err is removed);
> - Insert empty line before case MLXCPLD_LPCI2C_ACK_IND;
> - inside case MLXCPLD_LPCI2C_ACK_IND - avoid unnecessary
> indentation;
> - Remove case MLXCPLD_LPCI2C_ERR_IND and remove this macro;
> - Add empty lines in mlxcpld_i2c_xfer before/after mutex_lock/
> mutex_unlock;
> - In mlxcpld_i2c_probe add emtpy line after platform_set_drvdata;
> - Replace platfrom handle pdev in mlxcpld_i2c_priv with the pointer
> to the structure device;
> - Place assignment of base_addr near the others;
> - Enclose e-mail with <>;
> Fixes added by Vadim:
> - Change structure description format according to
> Documentation/kernel-documentation.rst guideline;
> - mlxcpld_i2c_wait_for_tc: return error if status reaches default case;
> v1->v2
> Fixes added by Vadim:
> - Put new record in Makefile in alphabetic order;
> - Remove http://www.mellanox.com from MAINTAINERS record;
> ---
> Documentation/i2c/busses/i2c-mlxcpld | 47 +++
> MAINTAINERS | 8 +
> drivers/i2c/busses/Kconfig | 11 +
> drivers/i2c/busses/Makefile | 1 +
> drivers/i2c/busses/i2c-mlxcpld.c | 544 +++++++++++++++++++++++++++++++++++
> 5 files changed, 611 insertions(+)
> create mode 100644 Documentation/i2c/busses/i2c-mlxcpld
> create mode 100644 drivers/i2c/busses/i2c-mlxcpld.c
>
> diff --git a/Documentation/i2c/busses/i2c-mlxcpld b/Documentation/i2c/busses/i2c-mlxcpld
> new file mode 100644
> index 0000000..0f8678a
> --- /dev/null
> +++ b/Documentation/i2c/busses/i2c-mlxcpld
> @@ -0,0 +1,47 @@
> +Driver i2c-mlxcpld
> +
> +Author: Michael Shych <michaelsh@xxxxxxxxxxxx>
> +
> +This is a for Mellanox I2C controller logic, implemented in Lattice CPLD
Grammar: "This is a <what> for Mellanox..."?
> +device.
> +Device supports:
> + - Master mode.
> + - One physical bus.
> + - Polling mode.
> +
> +This controller is equipped within the next Mellanox systems:
> +"msx6710", "msx6720", "msb7700", "msn2700", "msx1410", "msn2410", "msb7800",
> +"msn2740", "msn2100".
> +
> +The next transaction types are supported:
> + - Receive Byte/Block.
> + - Send Byte/Block.
> + - Read Byte/Block.
> + - Write Byte/Block.
> +
> +Registers:
> +CTRL 0x1 - control reg.
> + Resets all the registers.
> +HALF_CYC 0x4 - cycle reg.
> + Configure the width of I2C SCL half clock cycle (in 4 LPC_CLK
> + units).
> +I2C_HOLD 0x5 - hold reg.
> + OE (output enable) is delayed by value set to this register
> + (in LPC_CLK units)
> +CMD 0x6 - command reg.
> + Bit 7(lsb), 0 = write, 1 = read.
lsb? Why is lsb in bit 7? Isn't bit 7 msb per definition? Are you
referring to the fact that this bit is the lsb on-the-wire? I.e.
are you trying to say that the fields in this register are reversed
compared to the on-wire byte format? I assume so...
> + Bits [6:0] - the 7bit Address of the I2C device.
> + It should be written last as it triggers an I2C transaction.
...but it make me wonder if the byte is bit-reversed or if it is just
fields that are out of order? Probably not, but, odd!
> +NUM_DATA 0x7 - data size reg.
> + Number of address bytes to write in read transaction
s/address/data/ ???
> +NUM_ADDR 0x8 - address reg.
> + Number of address bytes to write in read transaction.
> +STATUS 0x9 - status reg.
> + Bit 0 - transaction is completed.
> + Bit 4 - ACK/NACK.
> +DATAx 0xa - 0x54 - 68 bytes data buffer regs.
> + For write transaction address is specified in four first bytes
> + (DATA1 - DATA4), data starting from DATA4.
> + For read transactions address is send in separate transaction and
s/address is send in/the address is sent in a/
> + specified in four first bytes (DATA0 - DATA3). Data is reading
s/in four/in the four/
s/reading/read/
> + starting from DATA0.
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 411e3b8..26d05f8 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -7881,6 +7881,14 @@ W: http://www.mellanox.com
> Q: http://patchwork.ozlabs.org/project/netdev/list/
> F: drivers/net/ethernet/mellanox/mlxsw/
>
> +MELLANOX MLXCPLD I2C DRIVER
> +M: Vadim Pasternak <vadimp@xxxxxxxxxxxx>
> +M: Michael Shych <michaelsh@xxxxxxxxxxxx>
> +L: linux-i2c@xxxxxxxxxxxxxxx
> +S: Supported
> +F: drivers/i2c/busses/i2c-mlxcpld.c
> +F: Documentation/i2c/busses/i2c-mlxcpld
> +
> MELLANOX MLXCPLD LED DRIVER
> M: Vadim Pasternak <vadimp@xxxxxxxxxxxx>
> L: linux-leds@xxxxxxxxxxxxxxx
> diff --git a/drivers/i2c/busses/Kconfig b/drivers/i2c/busses/Kconfig
> index d252276..6399cea 100644
> --- a/drivers/i2c/busses/Kconfig
> +++ b/drivers/i2c/busses/Kconfig
> @@ -1150,6 +1150,17 @@ config I2C_ELEKTOR
> This support is also available as a module. If so, the module
> will be called i2c-elektor.
>
> +config I2C_MLXCPLD
> + tristate "Mellanox I2C driver"
> + depends on X86_64
> + help
> + This exposes the Mellanox platform I2C busses to the linux I2C layer
> + for X86 based systems.
> + Controller is implemented as CPLD logic.
> +
> + This driver can also be built as a module. If so, the module will be
> + called as i2c-mlxcpld.
> +
> config I2C_PCA_ISA
> tristate "PCA9564/PCA9665 on an ISA bus"
> depends on ISA
> diff --git a/drivers/i2c/busses/Makefile b/drivers/i2c/busses/Makefile
> index 29764cc..645bf08 100644
> --- a/drivers/i2c/busses/Makefile
> +++ b/drivers/i2c/busses/Makefile
> @@ -116,6 +116,7 @@ obj-$(CONFIG_I2C_BCM_KONA) += i2c-bcm-kona.o
> obj-$(CONFIG_I2C_BRCMSTB) += i2c-brcmstb.o
> obj-$(CONFIG_I2C_CROS_EC_TUNNEL) += i2c-cros-ec-tunnel.o
> obj-$(CONFIG_I2C_ELEKTOR) += i2c-elektor.o
> +obj-$(CONFIG_I2C_MLXCPLD) += i2c-mlxcpld.o
> obj-$(CONFIG_I2C_OPAL) += i2c-opal.o
> obj-$(CONFIG_I2C_PCA_ISA) += i2c-pca-isa.o
> obj-$(CONFIG_I2C_SIBYTE) += i2c-sibyte.o
> diff --git a/drivers/i2c/busses/i2c-mlxcpld.c b/drivers/i2c/busses/i2c-mlxcpld.c
> new file mode 100644
> index 0000000..07d5657
> --- /dev/null
> +++ b/drivers/i2c/busses/i2c-mlxcpld.c
> @@ -0,0 +1,544 @@
> +/*
> + * Copyright (c) 2016 Mellanox Technologies. All rights reserved.
> + * Copyright (c) 2016 Michael Shych <michaels@xxxxxxxxxxxx>
> + *
> + * Redistribution and use in source and binary forms, with or without
> + * modification, are permitted provided that the following conditions are met:
> + *
> + * 1. Redistributions of source code must retain the above copyright
> + * notice, this list of conditions and the following disclaimer.
> + * 2. Redistributions in binary form must reproduce the above copyright
> + * notice, this list of conditions and the following disclaimer in the
> + * documentation and/or other materials provided with the distribution.
> + * 3. Neither the names of the copyright holders nor the names of its
> + * contributors may be used to endorse or promote products derived from
> + * this software without specific prior written permission.
> + *
> + * Alternatively, this software may be distributed under the terms of the
> + * GNU General Public License ("GPL") version 2 as published by the Free
> + * Software Foundation.
> + *
> + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
> + * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
> + * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
> + * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
> + * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
> + * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
> + * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
> + * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
> + * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
> + * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
> + * POSSIBILITY OF SUCH DAMAGE.
> + */
> +
> +#include <linux/delay.h>
> +#include <linux/i2c.h>
> +#include <linux/init.h>
> +#include <linux/io.h>
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/platform_device.h>
> +
> +/* General defines */
> +#define MLXPLAT_CPLD_LPC_I2C_BASE_ADDR 0x2000
> +#define MLXCPLD_I2C_DEVICE_NAME "i2c_mlxcpld"
> +#define MLXCPLD_I2C_VALID_FLAG (I2C_M_RECV_LEN | I2C_M_RD)
> +#define MLXCPLD_I2C_BUS_NUM 1
> +#define MLXCPLD_I2C_DATA_REG_SZ 36
> +#define MLXCPLD_I2C_MAX_ADDR_LEN 4
> +#define MLXCPLD_I2C_RETR_NUM 2
> +#define MLXCPLD_I2C_XFER_TO 500000 /* usec */
> +#define MLXCPLD_I2C_POLL_TIME 2000 /* usec */
> +
> +/* LPC I2C registers */
> +#define MLXCPLD_LPCI2C_LPF_REG 0x0
> +#define MLXCPLD_LPCI2C_CTRL_REG 0x1
> +#define MLXCPLD_LPCI2C_HALF_CYC_REG 0x4
> +#define MLXCPLD_LPCI2C_I2C_HOLD_REG 0x5
> +#define MLXCPLD_LPCI2C_CMD_REG 0x6
> +#define MLXCPLD_LPCI2C_NUM_DAT_REG 0x7
> +#define MLXCPLD_LPCI2C_NUM_ADDR_REG 0x8
> +#define MLXCPLD_LPCI2C_STATUS_REG 0x9
> +#define MLXCPLD_LPCI2C_DATA_REG 0xa
> +
> +/* LPC I2C masks and parametres */
> +#define MLXCPLD_LPCI2C_RST_SEL_MASK 0x1
> +#define MLXCPLD_LPCI2C_TRANS_END 0x1
> +#define MLXCPLD_LPCI2C_STATUS_NACK 0x10
> +#define MLXCPLD_LPCI2C_NO_IND 0
> +#define MLXCPLD_LPCI2C_ACK_IND 1
> +#define MLXCPLD_LPCI2C_NACK_IND 2
> +
> +/**
> + * struct mlxcpld_i2c_curr_transf - current transaction parameters:
"xfer" seems to be a more common abbreviation of "transfer".
> + * @cmd: command;
> + * @addr_width: address width;
> + * @data_len: data length;
> + * @cmd: command register;
> + * @msg_num: message number;
> + * @msg: pointer to message buffer;
> + */
> +
> +struct mlxcpld_i2c_curr_transf {
Dito.
> + u8 cmd;
> + u8 addr_width;
> + u8 data_len;
> + u8 msg_num;
> + struct i2c_msg *msg;
> +};
> +
> +/**
> + * struct mlxcpld_i2c_priv - private controller data:
> + * @adap: i2c adapter;
> + * @base_addr: base IO address;
> + * @lock: bus access lock;
> + * @xfer: current i2c transfer block;
> + * @dev: device handle;
> + */
> +
> +struct mlxcpld_i2c_priv {
> + struct i2c_adapter adap;
> + u32 base_addr;
> + struct mutex lock;
> + struct mlxcpld_i2c_curr_transf xfer;
> + struct device *dev;
> +};
> +
> +static void mlxcpld_i2c_lpc_write_buf(u8 *data, u8 len, u32 addr)
> +{
> + int i, nbyte, ndword;
> +
> + nbyte = len % 4;
> + ndword = len / 4;
> + for (i = 0; i < ndword; i++)
> + outl(*((u32 *)data + i), addr + i * 4);
> + ndword *= 4;
> + addr += ndword;
> + data += ndword;
> + for (i = 0; i < nbyte; i++)
> + outb(*(data + i), addr + i);
> +}
I find the below easier to read (untested):
static void mlxcpld_i2c_lpc_write_buf(u8 *data, u8 len, u32 addr)
{
int i;
for (i = 0; i < len - len % 4; i += 4)
outl(*(u32 *)(data + i), addr + i);
for (; i < len; ++i)
outb(*(data + i), addr + i);
}
> +
> +static void mlxcpld_i2c_lpc_read_buf(u8 *data, u8 len, u32 addr)
> +{
> + int i, nbyte, ndword;
> +
> + nbyte = len % 4;
> + ndword = len / 4;
> + for (i = 0; i < ndword; i++)
> + *((u32 *)data + i) = inl(addr + i * 4);
> + ndword *= 4;
> + addr += ndword;
> + data += ndword;
> + for (i = 0; i < nbyte; i++)
> + *(data + i) = inb(addr + i);
> +}
Similar to the above, of course.
> +
> +static void mlxcpld_i2c_read_comm(struct mlxcpld_i2c_priv *priv, u8 offs,
> + u8 *data, u8 datalen)
> +{
> + u32 addr = priv->base_addr + offs;
> +
> + switch (datalen) {
> + case 1:
> + *(data) = inb(addr);
> + break;
> + case 2:
> + *((u16 *)data) = inw(addr);
> + break;
> + case 3:
> + *((u16 *)data) = inw(addr);
> + *(data + 2) = inb(addr + 2);
> + break;
> + case 4:
> + *((u32 *)data) = inl(addr);
> + break;
> + default:
> + mlxcpld_i2c_lpc_read_buf(data, datalen, addr);
> + break;
> + }
> +}
> +
> +static void mlxcpld_i2c_write_comm(struct mlxcpld_i2c_priv *priv, u8 offs,
> + u8 *data, u8 datalen)
> +{
> + u32 addr = priv->base_addr + offs;
> +
> + switch (datalen) {
> + case 1:
> + outb(*(data), addr);
> + break;
> + case 2:
> + outw(*((u16 *)data), addr);
> + break;
> + case 3:
> + outw(*((u16 *)data), addr);
> + outb(*(data + 2), addr + 2);
> + break;
> + case 4:
> + outl(*((u32 *)data), addr);
> + break;
> + default:
> + mlxcpld_i2c_lpc_write_buf(data, datalen, addr);
> + break;
> + }
> +}
> +
> +/* Check validity of current i2c message and all transfer.
> + * Calculate also common length of all i2c messages in transfer.
> + */
Multiline comments should start with a /* on a line on its own,
to form symmetry with the trailing */.
> +static int mlxcpld_i2c_invalid_len(struct mlxcpld_i2c_priv *priv,
> + const struct i2c_msg *msg, u8 *comm_len)
> +{
> + u8 max_len = msg->flags == I2C_M_RD ? MLXCPLD_I2C_DATA_REG_SZ -
> + MLXCPLD_I2C_MAX_ADDR_LEN : MLXCPLD_I2C_DATA_REG_SZ;
> +
> + if (msg->len > max_len)
> + return -EINVAL;
> +
> + *comm_len += msg->len;
> + if (*comm_len > MLXCPLD_I2C_DATA_REG_SZ)
> + return -EINVAL;
> +
> + return 0;
> +}
> +
> +/* Check validity of received i2c messages parameters.
> + * Returns 0 if OK, other - in case of invalid parameters
> + * or common length of data that should be passed to CPLD
> + */
Dito.
> +static int mlxcpld_i2c_check_msg_params(struct mlxcpld_i2c_priv *priv,
> + struct i2c_msg *msgs, int num,
> + u8 *comm_len)
> +{
> + int i;
> +
> + if (!num) {
> + dev_err(priv->dev, "Incorrect 0 num of messages\n");
> + return -EINVAL;
> + }
> +
> + if (unlikely(msgs[0].addr > 0x7f)) {
> + dev_err(priv->dev, "Invalid address 0x%03x\n",
> + msgs[0].addr);
> + return -EINVAL;
> + }
> +
> + for (i = 0; i < num; ++i) {
> + if (unlikely(!msgs[i].buf)) {
> + dev_err(priv->dev, "Invalid buf in msg[%d]\n",
> + i);
> + return -EINVAL;
> + }
> + if (unlikely(msgs[0].addr != msgs[i].addr)) {
> + dev_err(priv->dev, "Invalid addr in msg[%d]\n",
> + i);
> + return -EINVAL;
> + }
> + if (unlikely(mlxcpld_i2c_invalid_len(priv, &msgs[i],
> + comm_len))) {
> + dev_err(priv->dev, "Invalid len %d msg[%d], addr 0x%x, lag %u\n",
> + msgs[i].len, i, msgs[i].addr, msgs[i].flags);
> + return -EINVAL;
> + }
> + }
> +
> + return 0;
> +}
> +
> +/* Check if transfer is completed and status of operation.
> + * Returns 0 - transfer completed (both ACK or NACK),
> + * negative - transfer isn't finished.
> + */
Dito.
> +static int mlxcpld_i2c_check_status(struct mlxcpld_i2c_priv *priv, int *status)
> +{
> + u8 val;
> +
> + mlxcpld_i2c_read_comm(priv, MLXCPLD_LPCI2C_STATUS_REG, &val, 1);
> +
> + if (val & MLXCPLD_LPCI2C_TRANS_END) {
> + if (val & MLXCPLD_LPCI2C_STATUS_NACK)
> + /* The slave is unable to accept the data. No such
> + * slave, command not understood, or unable to accept
> + * any more data.
> + */
Dito, and I see more below...
> + *status = MLXCPLD_LPCI2C_NACK_IND;
> + else
> + *status = MLXCPLD_LPCI2C_ACK_IND;
> + return 0;
> + }
> + *status = MLXCPLD_LPCI2C_NO_IND;
> +
> + return -EIO;
> +}
> +
> +static void mlxcpld_i2c_set_transf_data(struct mlxcpld_i2c_priv *priv,
> + struct i2c_msg *msgs, int num,
> + u8 comm_len)
> +{
> + priv->xfer.msg = msgs;
> + priv->xfer.msg_num = num;
> +
> + /*
> + * All upper layers currently are never use transfer with more than
> + * 2 messages. Actually, it's also not so relevant in Mellanox systems
> + * because of HW limitation. Max size of transfer is o more than 20B
> + * in current x86 LPCI2C bridge.
> + */
> + priv->xfer.cmd = msgs[num - 1].flags & I2C_M_RD;
> +
> + if (priv->xfer.cmd == I2C_M_RD && comm_len != msgs[0].len) {
> + priv->xfer.addr_width = msgs[0].len;
> + priv->xfer.data_len = comm_len - priv->xfer.addr_width;
> + } else {
> + priv->xfer.addr_width = 0;
> + priv->xfer.data_len = comm_len;
> + }
> +}
> +
> +/* Reset CPLD LPCI2C block */
> +static void mlxcpld_i2c_reset(struct mlxcpld_i2c_priv *priv)
> +{
> + u8 val;
> +
> + mutex_lock(&priv->lock);
> +
> + mlxcpld_i2c_read_comm(priv, MLXCPLD_LPCI2C_CTRL_REG, &val, 1);
> + val &= ~MLXCPLD_LPCI2C_RST_SEL_MASK;
> + mlxcpld_i2c_write_comm(priv, MLXCPLD_LPCI2C_CTRL_REG, &val, 1);
> +
> + mutex_unlock(&priv->lock);
> +}
> +
> +/* Make sure the CPLD is ready to start transmitting. */
> +static int mlxcpld_i2c_check_busy(struct mlxcpld_i2c_priv *priv)
> +{
> + u8 val;
> +
> + mlxcpld_i2c_read_comm(priv, MLXCPLD_LPCI2C_STATUS_REG, &val, 1);
> +
> + if (val & MLXCPLD_LPCI2C_TRANS_END)
> + return 0;
> +
> + return -EIO;
> +}
> +
> +static int mlxcpld_i2c_wait_for_free(struct mlxcpld_i2c_priv *priv)
> +{
> + int timeout = 0;
> +
> + do {
> + if (!mlxcpld_i2c_check_busy(priv))
> + break;
> + usleep_range(MLXCPLD_I2C_POLL_TIME / 2, MLXCPLD_I2C_POLL_TIME);
> + timeout += MLXCPLD_I2C_POLL_TIME;
> + } while (timeout <= MLXCPLD_I2C_XFER_TO);
> +
> + if (timeout > MLXCPLD_I2C_XFER_TO)
> + return -ETIMEDOUT;
> +
> + return 0;
> +}
> +
> +/*
> + * Wait for master transfer to complete.
> + * It puts current process to sleep until we get interrupt or timeout expires.
> + * Returns the number of transferred or read bytes or error (<0).
> + */
> +static int mlxcpld_i2c_wait_for_tc(struct mlxcpld_i2c_priv *priv)
> +{
> + int status, i, timeout = 0;
> + u8 datalen;
> +
> + do {
> + usleep_range(MLXCPLD_I2C_POLL_TIME / 2, MLXCPLD_I2C_POLL_TIME);
> + if (!mlxcpld_i2c_check_status(priv, &status))
> + break;
> + timeout += MLXCPLD_I2C_POLL_TIME;
> + } while (status == 0 && timeout < MLXCPLD_I2C_XFER_TO);
> +
> + switch (status) {
> + case MLXCPLD_LPCI2C_NO_IND:
> + return -ETIMEDOUT;
> +
> + case MLXCPLD_LPCI2C_ACK_IND:
> + if (priv->xfer.cmd != I2C_M_RD)
> + return (priv->xfer.addr_width + priv->xfer.data_len);
> +
> + if (priv->xfer.msg_num == 1)
> + i = 0;
> + else
> + i = 1;
> +
> + if (!priv->xfer.msg[i].buf)
> + return -EINVAL;
> +
> + /*
> + * Actual read data len will be always the same as
> + * requested len. 0xff (line pull-up) will be returned
> + * if slave has no data to return. Thus don't read
> + * MLXCPLD_LPCI2C_NUM_DAT_REG reg from CPLD.
> + */
> + datalen = priv->xfer.data_len;
> +
> + mlxcpld_i2c_read_comm(priv, MLXCPLD_LPCI2C_DATA_REG,
> + priv->xfer.msg[i].buf, datalen);
> +
> + return datalen;
> +
> + case MLXCPLD_LPCI2C_NACK_IND:
> + return -EAGAIN;
> +
> + default:
> + return -EINVAL;
> + }
> +}
> +
> +static void mlxcpld_i2c_xfer_msg(struct mlxcpld_i2c_priv *priv)
> +{
> + int i, len = 0;
> + u8 cmd;
> +
> + mlxcpld_i2c_write_comm(priv, MLXCPLD_LPCI2C_NUM_DAT_REG,
> + &priv->xfer.data_len, 1);
> + mlxcpld_i2c_write_comm(priv, MLXCPLD_LPCI2C_NUM_ADDR_REG,
> + &priv->xfer.addr_width, 1);
> +
> + for (i = 0; i < priv->xfer.msg_num; i++) {
> + if ((priv->xfer.msg[i].flags & I2C_M_RD) != I2C_M_RD) {
> + /* Don't write to CPLD buffer in read transaction */
> + mlxcpld_i2c_write_comm(priv, MLXCPLD_LPCI2C_DATA_REG +
> + len, priv->xfer.msg[i].buf,
> + priv->xfer.msg[i].len);
> + len += priv->xfer.msg[i].len;
> + }
> + }
> +
> + /* Set target slave address with command for master transfer.
> + * It should be latest executed function before CPLD transaction.
> + */
> + cmd = (priv->xfer.msg[0].addr << 1) | priv->xfer.cmd;
> + mlxcpld_i2c_write_comm(priv, MLXCPLD_LPCI2C_CMD_REG, &cmd, 1);
> +}
> +
> +/* Generic lpc-i2c transfer.
> + * Returns the number of processed messages or error (<0).
> + */
> +static int mlxcpld_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
> + int num)
> +{
> + struct mlxcpld_i2c_priv *priv = i2c_get_adapdata(adap);
> + u8 comm_len = 0;
> + int err;
> +
> + err = mlxcpld_i2c_check_msg_params(priv, msgs, num, &comm_len);
> + if (err) {
> + dev_err(priv->dev, "Incorrect message\n");
> + return err;
> + }
> +
> + /* Check bus state */
> + if (mlxcpld_i2c_wait_for_free(priv)) {
> + dev_err(priv->dev, "LPCI2C bridge is busy\n");
> +
> + /*
> + * Usually it means something serious has happened.
> + * We can not have unfinished previous transfer
> + * so it doesn't make any sense to try to stop it.
> + * Probably we were not able to recover from the
> + * previous error.
> + * The only reasonable thing - is soft reset.
> + */
> + mlxcpld_i2c_reset(priv);
> + if (mlxcpld_i2c_check_busy(priv)) {
> + dev_err(priv->dev, "LPCI2C bridge is busy after reset\n");
> + return -EIO;
> + }
> + }
> +
> + mlxcpld_i2c_set_transf_data(priv, msgs, num, comm_len);
> +
> + mutex_lock(&priv->lock);
> +
> + /* Do real transfer. Can't fail */
> + mlxcpld_i2c_xfer_msg(priv);
> +
> + /* Wait for transaction complete */
> + err = mlxcpld_i2c_wait_for_tc(priv);
> +
> + mutex_unlock(&priv->lock);
> +
> + return err < 0 ? err : num;
> +}
> +
> +static u32 mlxcpld_i2c_func(struct i2c_adapter *adap)
> +{
> + return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL | I2C_FUNC_SMBUS_BLOCK_DATA;
> +}
> +
> +static const struct i2c_algorithm mlxcpld_i2c_algo = {
> + .master_xfer = mlxcpld_i2c_xfer,
> + .functionality = mlxcpld_i2c_func
> +};
> +
> +static struct i2c_adapter mlxcpld_i2c_adapter = {
> + .owner = THIS_MODULE,
> + .name = "i2c-mlxcpld",
> + .class = I2C_CLASS_HWMON | I2C_CLASS_SPD,
> + .algo = &mlxcpld_i2c_algo,
> + .retries = MLXCPLD_I2C_RETR_NUM,
> + .nr = MLXCPLD_I2C_BUS_NUM,
> +};
> +
> +static int mlxcpld_i2c_probe(struct platform_device *pdev)
> +{
> + struct mlxcpld_i2c_priv *priv;
> + int err;
> +
> + priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
> + if (!priv)
> + return -ENOMEM;
> +
> + mutex_init(&priv->lock);
> + platform_set_drvdata(pdev, priv);
> +
> + priv->dev = &pdev->dev;
> +
> + /* Register with i2c layer */
> + mlxcpld_i2c_adapter.timeout = usecs_to_jiffies(MLXCPLD_I2C_XFER_TO);
> + priv->adap = mlxcpld_i2c_adapter;
> + priv->adap.dev.parent = &pdev->dev;
> + priv->base_addr = MLXPLAT_CPLD_LPC_I2C_BASE_ADDR;
> + i2c_set_adapdata(&priv->adap, priv);
> +
> + err = i2c_add_numbered_adapter(&priv->adap);
> + if (err)
> + mutex_destroy(&priv->lock);
> +
> + return err;
> +}
> +
> +static int mlxcpld_i2c_remove(struct platform_device *pdev)
> +{
> + struct mlxcpld_i2c_priv *priv = platform_get_drvdata(pdev);
> +
> + i2c_del_adapter(&priv->adap);
> + mutex_destroy(&priv->lock);
> +
> + return 0;
> +}
> +
> +static struct platform_driver mlxcpld_i2c_driver = {
> + .probe = mlxcpld_i2c_probe,
> + .remove = mlxcpld_i2c_remove,
> + .driver = {
> + .name = MLXCPLD_I2C_DEVICE_NAME,
> + },
> +};
> +
> +module_platform_driver(mlxcpld_i2c_driver);
> +
> +MODULE_AUTHOR("Michael Shych <michaels@xxxxxxxxxxxx>");
> +MODULE_DESCRIPTION("Mellanox I2C-CPLD controller driver");
> +MODULE_LICENSE("Dual BSD/GPL");
> +MODULE_ALIAS("platform:i2c-mlxcpld");
>