Re: [PATCH mtd] mtd:devices: Add Altera EPCQ Driver

[Viet Nga Dao]

On Tue, Jan 13, 2015 at 11:33 AM, Brian Norris
<computersforpeace@xxxxxxxxx> wrote:
> On Thu, Dec 18, 2014 at 12:23:16AM -0800, vndao@xxxxxxxxxx wrote:
>> From: Viet Nga Dao <vndao@xxxxxxxxxx>
>>
>> Altera EPCQ Controller is a soft IP which enables access to Altera EPCQ and
>> EPCS flash chips. This patch adds driver for these devices.
>>
>> Signed-off-by: Viet Nga Dao <vndao@xxxxxxxxxx>
>
> This drivers seems awfully similar to (and so I infer it is likely
> copy-and-pasted from) m25p80.c / spi-nor.c. Do you think it can be
> rewritten as a SPI NOR driver, under drivers/mtd/spi-nor/ ? It looks
> like these flash share most (all?) the same basic opcodes.
>
For Altera EPCQ flashes, almost operations are performed underline
hardware. Software only able to perform the following through
registers:
 -  read status register
 -  read id
 -  write status registers bit SR_BP0,SR_BP1, SR_BP2,SR_BP3, SR_TB
(http://www.altera.com.my/literature/hb/cfg/cfg_cf52012.pdf)
For read/write data: all the operations like QUAD_READ/WRITE,
FAST_READ/WRITE are handled by hardware as well. From software point
of view, there is no difference between these 2 modes.
That is why if rewrite the drivers to follow spi-nor structure, it
will require extra decoding works for the only few used opcodes.

>> ---
>>  .../devicetree/bindings/mtd/altera_epcq.txt        |   45 ++
>>  drivers/mtd/devices/Kconfig                        |   12 +
>>  drivers/mtd/devices/Makefile                       |    2 +-
>>  drivers/mtd/devices/altera_epcq.c                  |  804 ++++++++++++++++++++
>>  drivers/mtd/devices/altera_epcq.h                  |  130 ++++
>>  5 files changed, 992 insertions(+), 1 deletions(-)
>>  create mode 100644 Documentation/devicetree/bindings/mtd/altera_epcq.txt
>>  create mode 100644 drivers/mtd/devices/altera_epcq.c
>>  create mode 100644 drivers/mtd/devices/altera_epcq.h
>>
>> diff --git a/Documentation/devicetree/bindings/mtd/altera_epcq.txt b/Documentation/devicetree/bindings/mtd/altera_epcq.txt
>> new file mode 100644
>> index 0000000..d14f50e
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/mtd/altera_epcq.txt
>> @@ -0,0 +1,45 @@
>> +* MTD Altera EPCQ driver
>> +
>> +Required properties:
>> +- compatible: Should be "altr,epcq-1.0"
>> +- reg: Address and length of the register set  for the device. It contains
>> +  the information of registers in the same order as described by reg-names
>> +- reg-names: Should contain the reg names
>> +  "csr_base": Should contain the register configuration base address
>> +  "data_base": Should contain the data base address
>> +- is-epcs: boolean type.
>> +             If present, the device contains EPCS flashes.
>> +             Otherwise, it contains EPCQ flashes.
>> +- #address-cells: Must be <1>.
>> +- #size-cells: Must be <0>.
>> +- flash device tree subnode, there must be a node with the following fields:
>
> These subnodes definitely require a 'compatible' string. Perhaps they
> should be used to differentiate EPCS vs. EPCQ. Does "is-epcs" really
> need to be in the top-level controller node?
>
>> +     - reg: Should contain the flash id
>
> Should, or must? (This question is relevant, because you seem to make it
> optional in your code.) And what does the "flash ID" mean? It seems like
> you're using as a chip-select or bank index.
>
>> +     - #address-cells: please refer to /mtd/partition.txt
>> +     - #size-cells: please refer to /mtd/partition.txt
>> +     For partitions inside each flash, please refer to /mtd/partition.txt
>> +
>> +Example:
>> +
>> +                     epcq_controller_0: epcq@0x000000000 {
>> +                             compatible = "altr,epcq-1.0";
>> +                             reg = <0x00000001 0x00000000 0x00000020>,
>> +                                     <0x00000000 0x00000000 0x02000000>;
>> +                             reg-names = "csr_base", "data_base";
>> +                             #address-cells = <1>;
>> +                             #size-cells = <0>;
>> +                             flash0: epcq256@0 {
>> +                                     reg = <0>;
>> +                                     #address-cells = <1>;
>> +                                     #size-cells = <1>;
>> +                                     partition@0 {
>> +                                             /* 16 MB for raw data. */
>> +                                             label = "EPCQ Flash 0 raw data";
>> +                                             reg = <0x0 0x1000000>;
>> +                                     };
>> +                                     partition@1000000 {
>> +                                             /* 16 MB for jffs2 data. */
>> +                                             label = "EPCQ Flash 0 JFFS 2";
>> +                                             reg = <0x1000000 0x1000000>;
>> +                                     };
>> +                             };
>> +                     }; //end epcq@0x000000000 (epcq_controller_0)
>> diff --git a/drivers/mtd/devices/Kconfig b/drivers/mtd/devices/Kconfig
>> index c49d0b1..020b864 100644
>> --- a/drivers/mtd/devices/Kconfig
>> +++ b/drivers/mtd/devices/Kconfig
>> @@ -218,6 +218,18 @@ config MTD_ST_SPI_FSM
>>         SPI Fast Sequence Mode (FSM) Serial Flash Controller and support
>>         for a subset of connected Serial Flash devices.
>>
>> +config MTD_ALTERA_EPCQ
>> +     tristate "Support Altera EPCQ/EPCS Flash chips"
>> +     depends on OF
>> +     help
>> +       This enables access to Altera EPCQ/EPCS flash chips, used for data
>> +       storage. See the driver source for the current list,
>> +       or to add other chips.
>> +
>> +       If you want to compile this driver as a module ( = code which can be
>> +       inserted in and removed from the running kernel whenever you want),
>> +       say M here and read <file:Documentation/kbuild/modules.txt>.
>> +
>>  if MTD_DOCG3
>>  config BCH_CONST_M
>>       default 14
>> diff --git a/drivers/mtd/devices/Makefile b/drivers/mtd/devices/Makefile
>> index f0b0e61..b429c4d 100644
>> --- a/drivers/mtd/devices/Makefile
>> +++ b/drivers/mtd/devices/Makefile
>> @@ -16,6 +16,6 @@ obj-$(CONFIG_MTD_SPEAR_SMI) += spear_smi.o
>>  obj-$(CONFIG_MTD_SST25L)     += sst25l.o
>>  obj-$(CONFIG_MTD_BCM47XXSFLASH)      += bcm47xxsflash.o
>>  obj-$(CONFIG_MTD_ST_SPI_FSM)    += st_spi_fsm.o
>> -
>> +obj-$(CONFIG_MTD_ALTERA_EPCQ)                += altera_epcq.o
>>
>>  CFLAGS_docg3.o                       += -I$(src)
>> diff --git a/drivers/mtd/devices/altera_epcq.c b/drivers/mtd/devices/altera_epcq.c
>> new file mode 100644
>> index 0000000..09213d5
>> --- /dev/null
>> +++ b/drivers/mtd/devices/altera_epcq.c
>> @@ -0,0 +1,804 @@
>> +/*
>> + * Copyright (C) 2014 Altera Corporation. All rights reserved
>> + *
>> + * This program is free software; you can redistribute it and/or modify it
>> + * under the terms and conditions of the GNU General Public License,
>> + * version 2, as published by the Free Software Foundation.
>> + *
>> + * This program is distributed in the hope it will be useful, but WITHOUT
>> + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
>> + * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
>> + * more details.
>> + *
>> + * You should have received a copy of the GNU General Public License along with
>> + * this program.  If not, see <http://www.gnu.org/licenses/>.
>> + */
>> +
>> +#include <linux/clk.h>
>> +#include <linux/delay.h>
>> +#include <linux/device.h>
>> +#include <linux/err.h>
>> +#include <linux/errno.h>
>> +#include <linux/interrupt.h>
>> +#include <linux/io.h>
>> +#include <linux/ioport.h>
>> +#include <linux/jiffies.h>
>> +#include <linux/kernel.h>
>> +#include <linux/log2.h>
>> +#include <linux/module.h>
>> +#include <linux/mtd/mtd.h>
>> +#include <linux/mtd/partitions.h>
>> +#include <linux/mutex.h>
>> +#include <linux/of.h>
>> +#include <linux/of_address.h>
>> +#include <linux/param.h>
>> +#include <linux/platform_device.h>
>> +#include <linux/pm.h>
>> +#include <linux/sched.h>
>> +#include <linux/slab.h>
>> +#include <linux/wait.h>
>> +
>> +#include "altera_epcq.h"
>> +
>> +/* data structure to maintain flash ids from different vendors */
>> +struct flash_device {
>> +     char *name;
>> +     bool is_epcs;
>> +     u32 device_id;
>> +     uint32_t sectorsize_inbytes;
>> +     uint64_t size_inbytes;
>> +     u32 pagesize;
>> +};
>> +
>> +#define FLASH_ID(_n, _is_epcs, _id, _ssize, _size, _psize)   \
>> +{                            \
>> +     .name = (_n),           \
>> +     .is_epcs = (_is_epcs),          \
>> +     .device_id = (_id),     \
>> +     .sectorsize_inbytes = (_ssize), \
>> +     .size_inbytes = (_size),        \
>> +     .pagesize = (_psize),   \
>> +}
>> +
>> +static struct flash_device flash_devices[] = {
>> +     FLASH_ID("epcq16"    , 0, 0x15, 0x10000, 0x200000, 0x100),
>> +     FLASH_ID("epcq32"    , 0, 0x16, 0x10000, 0x400000, 0x100),
>> +     FLASH_ID("epcq64"    , 0, 0x17, 0x10000, 0x800000, 0x100),
>> +     FLASH_ID("epcq128"   , 0, 0x18, 0x10000, 0x1000000, 0x100),
>> +     FLASH_ID("epcq256"   , 0, 0x19, 0x10000, 0x2000000, 0x100),
>> +     FLASH_ID("epcq512"   , 0, 0x20, 0x10000, 0x4000000, 0x100),
>> +
>> +     FLASH_ID("epcs16"    , 1, 0x14, 0x10000, 0x200000, 0x100),
>> +     FLASH_ID("epcs64"    , 1, 0x16, 0x10000, 0x800000, 0x100),
>> +     FLASH_ID("epcs128"   , 1, 0x18, 0x40000, 0x1000000, 0x100),
>> +};
>> +
>> +static inline struct altera_epcq_flash *get_flash_data(struct mtd_info *mtd)
>> +{
>> +     return container_of(mtd, struct altera_epcq_flash, mtd);
>> +}
>> +
>> +static u32 altera_epcq_read_sr(struct altera_epcq *dev)
>> +{
>> +     return readl(dev->csr_base + EPCQ_SR_REG);
>> +}
>> +
>> +static int altera_epcq_wait_till_ready(struct altera_epcq *dev)
>> +{
>> +     unsigned long finish;
>> +     int status;
>> +
>> +     finish = jiffies + EPCQ_MAX_TIME_OUT;
>> +     do {
>> +             status = altera_epcq_read_sr(dev);
>> +             if (status < 0)
>> +                     return status;
>> +             else if (!(status & EPCQ_SR_WIP))
>> +                     return 0;
>> +
>> +             cond_resched();
>> +     } while (!time_after_eq(jiffies, finish));
>> +
>> +     dev_err(&dev->pdev->dev, "epcq controller is busy, timeout\n");
>> +     return -EBUSY;
>> +}
>> +
>> +static int get_flash_index(u32 flash_id, bool is_epcs)
>> +{
>> +     int index;
>> +
>> +     for (index = 0; index < ARRAY_SIZE(flash_devices); index++) {
>> +             if (flash_devices[index].device_id == flash_id &&
>> +                 flash_devices[index].is_epcs == is_epcs)
>> +                     return index;
>> +     }
>> +
>> +     /* Memory chip is not listed and not supported */
>> +     return -ENODEV;
>> +}
>> +
>> +static int altera_epcq_write_erase_check(struct altera_epcq *dev,
>> +                                      bool write_erase)
>> +{
>> +     u32 val;
>> +     u32 mask;
>> +
>> +     if (write_erase)
>> +             mask = EPCQ_ISR_ILLEGAL_WRITE_MASK;
>> +     else
>> +             mask = EPCQ_ISR_ILLEGAL_ERASE_MASK;
>> +
>> +     val = readl(dev->csr_base + EPCQ_ISR_REG);
>> +     if (val & mask) {
>> +             dev_err(&dev->pdev->dev,
>> +                     "write/erase failed, sector might be protected\n");
>> +             /*clear this status for next use*/
>> +             writel(val, dev->csr_base + EPCQ_ISR_REG);
>> +             return -EIO;
>> +     }
>> +     return 0;
>> +}
>> +
>> +static int altera_epcq_erase_chip(struct mtd_info *mtd)
>> +{
>> +     int ret;
>> +     u32 val;
>> +     struct altera_epcq *dev = mtd->priv;
>> +
>> +     /* Wait until finished previous write command. */
>> +     ret = altera_epcq_wait_till_ready(dev);
>
> This pattern is pretty silly. We don't need to have every operation
> check the status of the previous operation. Each operation should check
> itself. You obviously copied this one... but we recently changed that:
>
>     commit dfa9c0cba4ea20e766bbb4f89152b05d00ab9ab3
>     Author: Brian Norris <computersforpeace@xxxxxxxxx>
>     Date:   Wed Aug 6 18:16:57 2014 -0700
>
>         mtd: spi-nor: move "wait-till-ready" checks into erase/write
>         functions
>
>
>     https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=dfa9c0cba4ea20e766bbb4f89152b05d00ab9ab3
>
>> +     if (ret)
>> +             return ret;
>> +
>> +     /* erase chip. */
>> +     val = EPCQ_MEM_OP_BULK_ERASE_CMD;
>> +     writel(val, dev->csr_base + EPCQ_MEM_OP_REG);
>> +
>> +     /* Wait until finished previous write command. */
>> +     ret = altera_epcq_wait_till_ready(dev);
>> +     if (ret)
>> +             return ret;
>> +
>> +      /* check whether write triggered a illegal write interrupt */
>> +     ret = altera_epcq_write_erase_check(dev, 0);
>> +     if (ret < 0)
>> +             return ret;
>> +
>> +     return 0;
>> +}
>> +
>> +static int altera_epcq_addr_to_sector(struct altera_epcq_flash *flash,
>> +                                   int addr_offset)
>> +{
>> +     int sector = 0;
>> +     int i;
>> +
>> +     for (i = 0; i < flash->num_sectors; i++) {
>> +             if (addr_offset >= i * flash->mtd.erasesize && addr_offset <
>> +                 (i * flash->mtd.erasesize + flash->mtd.erasesize)) {
>> +                     sector = i;
>> +                     return sector;
>> +             }
>> +     }
>
> Uh, really? Am I crazy, or shouldn't this whole function just be a
> really simple arithmetic operation? Like:
>
>         return addr_offset >> mtd->erasesize_shift;
>
>> +     return -1;
>> +}
>> +
>> +static int altera_epcq_erase_sector(struct mtd_info *mtd,
>> +                                 int addr_offset)
>> +{
>> +     struct altera_epcq_flash *flash = get_flash_data(mtd);
>> +     struct altera_epcq *dev = mtd->priv;
>> +     u32 val;
>> +     int ret;
>> +     int sector_value;
>> +
>> +     ret = altera_epcq_wait_till_ready(dev);
>> +     if (ret)
>> +             return ret;
>> +
>> +     sector_value = altera_epcq_addr_to_sector(flash, addr_offset);
>> +
>> +     /* sanity check that block_offset is a valid sector number */
>> +     if (sector_value < 0)
>> +             return -EINVAL;
>> +
>> +     /* sector value should occupy bits 17:8 */
>> +     val = (sector_value << 8) & EPCQ_MEM_OP_SECTOR_VALUE_MASK;
>> +
>> +     /* sector erase commands occupies lower 2 bits */
>> +     val |= EPCQ_MEM_OP_SECTOR_ERASE_CMD;
>> +
>> +     /* write sector erase command to EPCQ_MEM_OP register*/
>> +     writel(val, dev->csr_base + EPCQ_MEM_OP_REG);
>> +
>> +     ret = altera_epcq_wait_till_ready(dev);
>> +     if (ret)
>> +             return ret;
>> +
>> +      /* check whether write triggered a illegal write interrupt */
>
> ^^ extra space here? You have <TAB><SPACE>/* check [...]
>
>> +     ret = altera_epcq_write_erase_check(dev, 0);
>> +     if (ret < 0)
>> +             return ret;
>> +
>> +     return 0;
>> +}
>> +
>> +static int altera_epcq_erase(struct mtd_info *mtd, struct erase_info *e_info)
>> +{
>> +     u32 addr;
>> +     int ret;
>> +     u32 len;
>> +     struct altera_epcq_flash *flash = get_flash_data(mtd);
>> +     struct altera_epcq *dev = mtd->priv;
>> +
>> +     addr = e_info->addr;
>> +     len = e_info->len;
>> +
>> +     if (flash->bank > dev->num_flashes - 1) {
>> +             dev_err(&dev->pdev->dev, "Invalid chip id\n");
>> +             return -EINVAL;
>> +     }
>> +     mutex_lock(&flash->lock);
>> +
>> +     /*erase whole chip*/
>> +     if (len == mtd->size) {
>> +             if (altera_epcq_erase_chip(mtd)) {
>> +                     e_info->state = MTD_ERASE_FAILED;
>> +                     mutex_unlock(&flash->lock);
>> +                     return -EIO;
>> +             }
>> +     /*"sector"-at-a-time erase*/
>> +     } else {
>> +             while (len) {
>> +                     ret = altera_epcq_erase_sector(mtd, addr);
>> +                     if (ret) {
>> +                             e_info->state = MTD_ERASE_FAILED;
>> +                             mutex_unlock(&flash->lock);
>> +                             return -EIO;
>> +                     }
>> +                     addr += mtd->erasesize;
>> +                     if (len < mtd->erasesize)
>> +                             len = 0;
>> +                     else
>> +                             len -= mtd->erasesize;
>> +             }
>> +     }
>> +     mutex_unlock(&flash->lock);
>> +     e_info->state = MTD_ERASE_DONE;
>> +     mtd_erase_callback(e_info);
>> +
>> +     return 0;
>> +}
>> +
>> +static int altera_epcq_read(struct mtd_info *mtd, loff_t from, size_t len,
>> +                         size_t *retlen, u8 *buf)
>> +{
>> +     struct altera_epcq_flash *flash = get_flash_data(mtd);
>> +     struct altera_epcq *dev = mtd->priv;
>> +     void *src;
>> +     int ret = 0;
>> +
>> +     if (!flash || !dev)
>> +             return -ENODEV;
>
> Why would either of these be 0? If they are, you have much bigger
> problems, since you aren't checking these almost anywhere else. And the
> !flash check is pretty odd, since get_flash_data() is using
> container_of(), which is not likely to give you exactly 0...
>
>> +
>> +     if (flash->bank > dev->num_flashes - 1) {
>> +             dev_err(&dev->pdev->dev, "Invalid chip id\n");
>> +             return -EINVAL;
>> +     }
>> +
>> +     src = dev->data_base + from;
>> +
>> +     mutex_lock(&flash->lock);
>> +     /* wait till previous write/erase is done. */
>> +     ret = altera_epcq_wait_till_ready(dev);
>> +     if (ret)
>> +             goto err;
>> +
>> +     memcpy_fromio(buf, (u8 *)src, len);
>
> Drop the cast. Also, you get sparse warnings because you're dropping the
> __iomem. Why not just this?
>
>         memcpy_fromio(buf, dev->data_base + from, len);
>
> (BTW, you might consider running sparse on all your code. See
> Documentation/sparse.txt. It tells you how to get it, but you can often
> just download it through your distro's package manager.)
>
>> +     *retlen = len;
>> +
>> +err:
>> +     mutex_unlock(&flash->lock);
>> +     return ret;
>> +}
>> +
>> +static int altera_epcq_write(struct mtd_info *mtd, loff_t to, size_t len,
>> +                          size_t *retlen, const u8 *buf)
>> +{
>> +     struct altera_epcq_flash *flash = get_flash_data(mtd);
>> +     struct altera_epcq *dev = mtd->priv;
>> +     void *dest;
>> +     int ret = 0;
>> +
>> +     if (!flash || !dev)
>> +             return -ENODEV;
>
> Also here. I don't think you need these checks.
>
>> +
>> +     if (flash->bank > dev->num_flashes - 1) {
>> +             dev_err(&dev->pdev->dev, "Invalid chip id\n");
>> +             return -EINVAL;
>> +     }
>> +     dest = dev->data_base + to;
>> +
>> +     mutex_lock(&flash->lock);
>> +
>> +     /* wait until finished previous write command. */
>> +     ret = altera_epcq_wait_till_ready(dev);
>> +     if (ret)
>> +             goto err;
>> +
>> +     memcpy_toio(dest, buf, len);
>
> Similar. Why not just this?
>
>         memcpy_toio(dev->data_base + to, buf, len);
>
>> +     *retlen += len;
>> +
>> +     /* wait until finished previous write command. */
>> +     ret = altera_epcq_wait_till_ready(dev);
>> +     if (ret)
>> +             goto err;
>> +
>> +      /* check whether write triggered a illegal write interrupt */
>> +     ret = altera_epcq_write_erase_check(dev, 1);
>> +     if (ret < 0)
>> +             goto err;
>> +
>> +err:
>> +     mutex_unlock(&flash->lock);
>> +     return ret;
>> +}
>> +
>> +static int altera_epcq_lock(struct mtd_info *mtd, loff_t ofs, uint64_t len)
>> +{
>> +     struct altera_epcq_flash *flash = get_flash_data(mtd);
>> +     struct altera_epcq *dev = mtd->priv;
>> +     uint32_t offset = ofs;
>> +     int ret = 0;
>> +     u32 sector_start, sector_end;
>> +     u32 num_sectors;
>> +     u32 mem_op;
>> +     unsigned sr_bp = 0;
>> +     unsigned sr_tb = 0;
>> +
>> +     sector_start = altera_epcq_addr_to_sector(flash, offset);
>> +     sector_end = altera_epcq_addr_to_sector(flash, offset + len);
>> +     num_sectors = flash->num_sectors;
>> +     dev_dbg(&dev->pdev->dev,
>> +             "%s: num_setor is %u,sector start is %u,sector end is %u\n",
>> +             __func__, num_sectors, sector_start, sector_end);
>> +
>> +     mutex_lock(&flash->lock);
>> +     /* wait until finished previous write command. */
>> +     ret = altera_epcq_wait_till_ready(dev);
>> +     if (ret)
>> +             goto err;
>> +
>> +     if (sector_start >= num_sectors/2) {
>
> It's preferable to have spaces around operators. So 'num_sectors / 2'.
> The same thing comes up in several other places.
>
>> +             if (sector_start < num_sectors-(num_sectors / 4))
>> +                     sr_bp = __ilog2_u32(num_sectors);
>> +             else if (sector_start < num_sectors-(num_sectors / 8))
>> +                     sr_bp = __ilog2_u32(num_sectors) - 1;
>> +             else if (sector_start < num_sectors-(num_sectors / 16))
>> +                     sr_bp = __ilog2_u32(num_sectors) - 2;
>> +             else if (sector_start < num_sectors-(num_sectors / 32))
>> +                     sr_bp = __ilog2_u32(num_sectors) - 3;
>> +             else if (sector_start < num_sectors-(num_sectors / 64))
>> +                     sr_bp = __ilog2_u32(num_sectors) - 4;
>> +             else if (sector_start < num_sectors-(num_sectors / 128))
>> +                     sr_bp = __ilog2_u32(num_sectors) - 5;
>> +             else if (sector_start < num_sectors-(num_sectors / 256))
>> +                     sr_bp = __ilog2_u32(num_sectors) - 6;
>> +             else if (sector_start < num_sectors-(num_sectors / 512))
>> +                     sr_bp = __ilog2_u32(num_sectors) - 7;
>> +             else if (sector_start < num_sectors-(num_sectors / 1024))
>> +                     sr_bp = __ilog2_u32(num_sectors) - 8;
>> +             else
>> +                     sr_bp = 0;  /* non area protected */
>
> Yikes, that's ugly! And I'm not sure it matches the EPCQ doc I found.
> I'm pretty sure you can rewrite this if/else-if/else block in about 1
> line though.
>
>> +
>> +             if (sr_bp < 0) {
>
> sr_bp is unsigned, so this is never true.
>
>> +                     dev_err(&dev->pdev->dev, "%s: address is out of range\n"
>> +                             , __func__);
>> +                     ret = -EINVAL;
>> +                     goto err;
>> +             }
>> +             /*set TB = 0*/
>> +             sr_tb = 0;
>> +
>> +     } else {
>> +             if (sector_end < 1)
>> +                     sr_bp = 1;
>> +             else if (sector_end < 2)
>> +                     sr_bp = 2;
>> +             else if (sector_end < 4)
>> +                     sr_bp = 3;
>> +             else if (sector_end < 8)
>> +                     sr_bp = 4;
>> +             else if (sector_end < 16)
>> +                     sr_bp = 5;
>> +             else if (sector_end < 32)
>> +                     sr_bp = 6;
>> +             else if (sector_end < 64)
>> +                     sr_bp = 7;
>> +             else if (sector_end < 128)
>> +                     sr_bp = 8;
>> +             else if (sector_end < 256)
>> +                     sr_bp = 9;
>> +             else if (sector_end < 512)
>> +                     sr_bp = 10;
>> +             else
>> +                     sr_bp = 16; /*protect all areas*/
>
> Again, this is ugly. How about this?
>
>         sr_bp = fls(sector_end) + 1;
>
>> +
>> +             sr_tb = 1;
>> +     }
>> +
>> +     mem_op = (sr_tb << 12) | (sr_bp << 8);
>> +     mem_op &= EPCQ_MEM_OP_SECTOR_PROTECT_VALUE_MASK;
>> +     mem_op |= EPCQ_MEM_OP_SECTOR_PROTECT_CMD;
>> +     writel(mem_op, dev->csr_base + EPCQ_MEM_OP_REG);
>> +
>> +err:
>> +     mutex_unlock(&flash->lock);
>> +     return ret;
>> +}
>> +
>> +static int altera_epcq_unlock(struct mtd_info *mtd, loff_t ofs, uint64_t len)
>> +{
>> +     struct altera_epcq_flash *flash = get_flash_data(mtd);
>> +     struct altera_epcq *dev = mtd->priv;
>> +
>> +     int ret = 0;
>> +     u32 mem_op;
>> +
>> +     mutex_lock(&flash->lock);
>> +     /* wait until finished previous write command. */
>> +     ret = altera_epcq_wait_till_ready(dev);
>> +     if (ret)
>> +             goto err;
>> +     dev_info(&dev->pdev->dev, "Unlock all protected area\n");
>> +     mem_op = 0;
>> +     mem_op &= EPCQ_MEM_OP_SECTOR_PROTECT_VALUE_MASK;
>> +     mem_op |= EPCQ_MEM_OP_SECTOR_PROTECT_CMD;
>> +     writel(mem_op, dev->csr_base + EPCQ_MEM_OP_REG);
>> +
>> +err:
>> +     mutex_unlock(&flash->lock);
>> +     return ret;
>> +}
>> +
>> +static void altera_epcq_chip_select(struct altera_epcq *dev, u32 bank)
>> +{
>> +     u32 val = 0;
>> +
>> +     switch (bank) {
>> +     case 0:
>> +             val = EPCQ_CHIP_SELECT_0;
>> +             break;
>> +     case 1:
>> +             val = EPCQ_CHIP_SELECT_1;
>> +             break;
>> +     case 2:
>> +             val = EPCQ_CHIP_SELECT_2;
>> +             break;
>> +     default:
>> +             return;
>> +     }
>> +
>> +     writel(val, dev->csr_base + EPCQ_CHIP_SELECT_REG);
>> +}
>> +
>> +static int altera_epcq_probe_flash(struct altera_epcq *dev, u32 bank)
>> +{
>> +     int ret = 0;
>> +     u32 val = 0;
>> +
>> +     mutex_lock(&dev->lock);
>> +
>> +     /*select bank*/
>
> Comment spacing, here and elsewhere:
>
>         /* select bank */
>
>> +     altera_epcq_chip_select(dev, bank);
>> +
>> +     ret = altera_epcq_wait_till_ready(dev);
>> +     if (ret)
>> +             goto err;
>> +
>> +     /* get device sillicon id */
>> +     if (dev->is_epcs)
>> +             val = readl(dev->csr_base + EPCQ_SID_REG);
>> +     else
>> +             val = readl(dev->csr_base + EPCQ_RDID_REG);
>> +
>> +     /* get flash index based on the device list*/
>> +     ret = get_flash_index(val, dev->is_epcs);
>> +     return 0;
>> +err:
>> +     mutex_unlock(&dev->lock);
>> +     return ret;
>> +}
>> +
>> +static int altera_epcq_probe_config_dt(struct platform_device *pdev,
>> +                                    struct device_node *np,
>> +                                    struct altera_epcq_plat_data *pdata)
>> +{
>> +     struct device_node *pp = NULL;
>> +     struct resource *epcq_res;
>> +     int i = 0;
>> +     u32 id;
>> +
>> +     pdata->is_epcs = of_property_read_bool(np, "is-epcs");
>> +
>> +     epcq_res = platform_get_resource_byname(pdev, IORESOURCE_MEM,
>> +                                             "csr_base");
>> +     if (!epcq_res) {
>
> devm_ioremap_resource() will check the that 'epcq_res' is valid, so you
> don't need this whole 'if' block.
>
>> +             dev_err(&pdev->dev, "resource csr base is not defined\n");
>> +             return -ENODEV;
>> +     }
>> +
>> +     pdata->csr_base = devm_ioremap_resource(&pdev->dev, epcq_res);
>> +     if (IS_ERR(pdata->csr_base)) {
>> +             dev_err(&pdev->dev, "%s: ERROR: failed to map csr base\n",
>> +                     __func__);
>> +             return PTR_ERR(pdata->csr_base);
>> +     }
>> +
>> +     epcq_res = platform_get_resource_byname(pdev, IORESOURCE_MEM,
>> +                                             "data_base");
>> +     if (!epcq_res) {
>
> Same here.
>
>> +             dev_err(&pdev->dev, "resource data base is not defined\n");
>> +             return -ENODEV;
>> +     }
>> +
>> +     pdata->data_base = devm_ioremap_resource(&pdev->dev, epcq_res);
>> +     if (IS_ERR(pdata->data_base)) {
>> +             dev_err(&pdev->dev, "%s: ERROR: failed to map data base\n",
>> +                     __func__);
>> +             return PTR_ERR(pdata->data_base);
>> +     }
>> +
>> +     pdata->board_flash_info = devm_kzalloc(&pdev->dev,
>> +                                            sizeof(*pdata->board_flash_info),
>> +                                            GFP_KERNEL);
>> +
>> +     /* Fill structs for each subnode (flash device) */
>> +     while ((pp = of_get_next_child(np, pp))) {
>
> for_each_available_child_of_node()?
>
>> +             struct altera_epcq_flash_info *flash_info;
>> +
>> +             flash_info = &pdata->board_flash_info[i];
>
> This is never used. Either use it below, or drop the local variable.
>
>> +             pdata->np[i] = pp;
>> +
>> +             /* Read bank id from DT */
>> +             if (of_get_property(pp, "reg", &id))
>
> Is this property optional? Your DT binding doc doesn't make it clear,
> but it seems like a property which would be wise to require (i.e., not
> optional).
>
>> +                     pdata->board_flash_info[i].bank = id;
>> +             i++;
>> +     }
>> +     pdata->num_flashes = i;
>> +     return 0;
>> +}
>> +
>> +static int altera_epcq_setup_banks(struct platform_device *pdev,
>> +                                u32 bank, struct device_node *np,
>> +                                struct altera_epcq_plat_data *pdata)
>> +{
>> +     struct altera_epcq *dev = platform_get_drvdata(pdev);
>> +     struct mtd_part_parser_data ppdata = {};
>> +     struct altera_epcq_flash_info *flash_info;
>> +     struct altera_epcq_flash *flash;
>> +     struct mtd_partition *parts = NULL;
>
> Drop this variable. Just use NULL directly below.
>
>> +     int count = 0;
>
> Same. Just use 0 below.
>
>> +     int flash_index;
>> +     int ret = 0;
>> +     uint64_t size;
>> +     uint32_t sector_size;
>> +
>> +     flash_info = &pdata->board_flash_info[bank];
>> +     if (!flash_info)
>> +             return -ENODEV;
>> +
>> +     if (bank > pdata->num_flashes - 1)
>> +             return -EINVAL;
>> +
>> +     flash = devm_kzalloc(&pdev->dev, sizeof(*flash), GFP_KERNEL);
>> +     if (!flash)
>> +             return -ENOMEM;
>> +     flash->bank = bank;
>> +
>> +     mutex_init(&flash->lock);
>> +
>> +     /* verify whether flash is really present on board */
>> +     flash_index = altera_epcq_probe_flash(dev, bank);
>> +     if (flash_index < 0) {
>> +             dev_info(&dev->pdev->dev, "epcq:flash%d not found\n",
>> +                      flash->bank);
>> +             return flash_index;
>> +     }
>> +
>> +     dev->flash[bank] = flash;
>> +
>> +     size = flash_devices[flash_index].size_inbytes;
>> +     sector_size = flash_devices[flash_index].sectorsize_inbytes;
>> +     /*use do_div instead of plain div to avoid linker err*/
>> +     do_div(size, sector_size);
>> +     flash->num_sectors = size;
>> +
>> +     /*mtd framework */
>> +     flash->mtd.priv = dev;
>> +     flash->mtd.name = flash_devices[flash_index].name;
>> +     flash->mtd.type = MTD_NORFLASH;
>> +     flash->mtd.writesize = 1;
>> +     flash->mtd.flags = MTD_CAP_NORFLASH;
>> +     flash->mtd.size = flash_devices[flash_index].size_inbytes;
>> +     flash->mtd.erasesize = flash_devices[flash_index].sectorsize_inbytes;
>> +     flash->mtd._erase = altera_epcq_erase;
>> +     flash->mtd._read = altera_epcq_read;
>> +     flash->mtd._write = altera_epcq_write;
>> +     flash->mtd._lock = altera_epcq_lock;
>> +     flash->mtd._unlock = altera_epcq_unlock;
>> +
>> +     dev_info(&pdev->dev, "mtd .name=%s .size=0x%llx (%lluM)\n",
>> +              flash->mtd.name, (long long)flash->mtd.size,
>> +              (long long)(flash->mtd.size >> 20));
>> +
>> +     dev_info(&pdev->dev, ".erasesize = 0x%x(%uK)\n",
>> +              flash->mtd.erasesize, flash->mtd.erasesize >> 10);
>> +
>> +     ppdata.of_node = np;
>> +
>> +     ret = mtd_device_parse_register(&flash->mtd, NULL, &ppdata, parts,
>> +                                     count);
>> +     if (ret) {
>> +             dev_err(&pdev->dev, "Err MTD partition=%d\n", ret);
>> +             goto err;
>
> You don't want to unregister a MTD that failed to register. The MTD core
> code should handle that itself.
>
> Instead of this if (ret) {} block, I'd just make this:
>
>         return mtd_device_parse_register(&flash->mtd, NULL, &ppdata, NULL, 0);
>
>> +     }
>> +
>> +     return 0;
>> +
>> +err:
>> +     mtd_device_unregister(&flash->mtd);
>> +     return ret;
>> +}
>> +
>> +static int altera_epcq_probe(struct platform_device *pdev)
>> +{
>> +     struct device_node *np = pdev->dev.of_node;
>> +     struct altera_epcq_plat_data *pdata = NULL;
>> +     struct altera_epcq *dev;
>> +     int ret = 0;
>> +     int i;
>> +
>> +     if (!np) {
>> +             ret = -ENODEV;
>> +             dev_err(&pdev->dev, "no device found\n");
>> +             goto err;
>> +     }
>> +
>> +     pdata = devm_kzalloc(&pdev->dev,
>> +                          sizeof(struct altera_epcq_plat_data),
>> +                          GFP_KERNEL);
>> +
>> +     if (!pdata) {
>> +             ret = -ENOMEM;
>> +             dev_err(&pdev->dev, "%s: ERROR: no memory\n", __func__);
>
> Unnecessary print. The MM code will print plenty of info if you're
> out of memory.
>
>> +             goto err;
>> +     }
>> +     ret = altera_epcq_probe_config_dt(pdev, np, pdata);
>> +     if (ret) {
>> +             ret = -ENODEV;
>> +             dev_err(&pdev->dev, "probe fail\n");
>> +             goto err;
>> +     }
>> +
>> +     dev = devm_kzalloc(&pdev->dev, sizeof(*dev), GFP_ATOMIC);
>> +     if (!dev) {
>> +             ret = -ENOMEM;
>> +             dev_err(&pdev->dev, "mem alloc fail\n");
>
> Same here.
>
>> +             goto err;
>> +     }
>> +     mutex_init(&dev->lock);
>> +     dev->pdev = pdev;
>> +     dev->is_epcs = pdata->is_epcs;
>> +     dev->csr_base = pdata->csr_base;
>> +     dev->data_base = pdata->data_base;
>> +
>> +     /*check number of flashes*/
>> +     dev->num_flashes = pdata->num_flashes;
>> +     if (dev->num_flashes > MAX_NUM_FLASH_CHIP) {
>> +             dev_err(&pdev->dev, "exceeding max number of flashes\n");
>> +             dev->num_flashes = MAX_NUM_FLASH_CHIP;
>> +     }
>> +
>> +     /* check clock*/
>> +     dev->clk = devm_clk_get(&pdev->dev, NULL);
>> +     if (IS_ERR(dev->clk)) {
>> +             ret = PTR_ERR(dev->clk);
>> +             goto err;
>> +     }
>> +     ret = clk_prepare_enable(dev->clk);
>> +     if (ret)
>> +             goto err;
>> +
>> +     platform_set_drvdata(pdev, dev);
>> +
>> +     /* loop for each serial flash which is connected to epcq */
>> +     for (i = 0; i < dev->num_flashes; i++) {
>> +             ret = altera_epcq_setup_banks(pdev, i, pdata->np[i], pdata);
>> +             if (ret) {
>> +                     dev_err(&pdev->dev, "bank setup failed\n");
>> +                     goto err_bank_setup;
>> +             }
>> +     }
>> +
>> +     return 0;
>> +
>> +err_bank_setup:
>> +     clk_disable_unprepare(dev->clk);
>> +err:
>> +     return ret;
>> +}
>> +
>> +static int altera_epcq_remove(struct platform_device *pdev)
>> +{
>> +     struct altera_epcq *dev;
>> +     struct altera_epcq_flash *flash;
>> +     int ret, i;
>> +
>> +     dev = platform_get_drvdata(pdev);
>> +
>> +     /* clean up for all nor flash */
>> +     for (i = 0; i < dev->num_flashes; i++) {
>> +             flash = dev->flash[i];
>> +             if (!flash)
>> +                     continue;
>> +
>> +             /* clean up mtd stuff */
>> +             ret = mtd_device_unregister(&flash->mtd);
>> +             if (ret)
>> +                     dev_err(&pdev->dev, "error removing mtd\n");
>> +     }
>> +
>> +     clk_disable_unprepare(dev->clk);
>> +
>> +     return 0;
>> +}
>> +
>> +#ifdef CONFIG_PM
>
> Make this CONFIG_PM_SLEEP.
>
>> +static int altera_epcq_suspend(struct device *dev)
>> +{
>> +     struct altera_epcq *sdev = dev_get_drvdata(dev);
>> +
>> +     clk_disable_unprepare(sdev->clk);
>> +
>> +     return 0;
>> +}
>> +
>> +static int altera_epcq_resume(struct device *dev)
>> +{
>> +     struct altera_epcq *sdev = dev_get_drvdata(dev);
>> +     int ret = -EPERM;
>
> Drop 'ret'.
>
>> +
>> +     ret = clk_prepare_enable(sdev->clk);
>
> Just:
>
>         return clk_prepare_enable(sdev->clk);
>
>> +
>> +     return ret;
>> +}
>> +
>> +static SIMPLE_DEV_PM_OPS(altera_epcq_pm_ops, altera_epcq_suspend,
>> +                      altera_epcq_resume);
>> +#endif
>> +
>> +static const struct of_device_id altera_epcq_id_table[] = {
>> +     { .compatible = "altr,epcq-1.0" },
>> +     {}
>> +};
>> +MODULE_DEVICE_TABLE(of, altera_epcq_id_table);
>> +
>> +static struct platform_driver altera_epcq_driver = {
>> +     .driver = {
>> +             .name = ALTERA_EPCQ_RESOURCE_NAME,
>> +             .bus = &platform_bus_type,
>> +             .owner = THIS_MODULE,
>
> The .owner assignment is no longer necessary.
>
>> +             .of_match_table = altera_epcq_id_table,
>> +#ifdef CONFIG_PM
>
> Also CONFIG_PM_SLEEP.
>
>> +             .pm = &altera_epcq_pm_ops,
>> +#endif
>> +     },
>> +     .probe = altera_epcq_probe,
>> +     .remove = altera_epcq_remove,
>> +};
>> +module_platform_driver(altera_epcq_driver);
>> +
>> +MODULE_AUTHOR("Viet Nga Dao <vndao@xxxxxxxxxx>");
>> +MODULE_DESCRIPTION("MTD Altera EPCQ Driver");
>> +MODULE_LICENSE("GPL v2");
>> diff --git a/drivers/mtd/devices/altera_epcq.h b/drivers/mtd/devices/altera_epcq.h
>> new file mode 100644
>> index 0000000..c3d15e5
>> --- /dev/null
>> +++ b/drivers/mtd/devices/altera_epcq.h
>> @@ -0,0 +1,130 @@
>> +/*
>> + * Copyright (C) 2014 Altera Corporation. All rights reserved
>> + *
>> + * This program is free software; you can redistribute it and/or modify it
>> + * under the terms and conditions of the GNU General Public License,
>> + * version 2, as published by the Free Software Foundation.
>> + *
>> + * This program is distributed in the hope it will be useful, but WITHOUT
>> + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
>> + * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
>> + * more details.
>> + *
>> + * You should have received a copy of the GNU General Public License along with
>> + * this program.  If not, see <http://www.gnu.org/licenses/>.
>> + */
>> +
>> +#ifndef __ALTERA_ECPQ_H
>> +#define __ALTERA_ECPQ_H
>> +
>> +#define ALTERA_EPCQ_RESOURCE_NAME        "altera_epcq"
>> +/* max possible slots for serial flash chip in the EPCQ controller */
>> +#define MAX_NUM_FLASH_CHIP   3
>> +
>> +/* macro to define partitions for flash devices */
>> +#define DEFINE_PARTS(n, of, s)               \
>
> This macro is not used anywhere. Drop it?
>
>> +{                                    \
>> +     .name = n,                      \
>> +     .offset = of,                   \
>> +     .size = s,                      \
>> +}
>> +
>> +struct altera_epcq_flash_info {
>> +     u32 bank;
>> +     struct mtd_partition *partitions;
>> +     int nr_partitions;
>> +};
>> +
>> +struct altera_epcq_plat_data {
>> +     void __iomem *csr_base;
>> +     void __iomem *data_base;
>> +     bool is_epcs;
>> +     u32 num_flashes;
>> +     struct altera_epcq_flash_info *board_flash_info;
>> +     struct device_node *np[MAX_NUM_FLASH_CHIP];
>> +};
>> +
>> +struct altera_epcq {
>> +     struct clk *clk;
>> +     bool is_epcs;
>> +     struct mutex lock;      /*device lock*/
>> +     void __iomem *csr_base;
>> +     void __iomem *data_base;
>> +     struct platform_device *pdev;
>> +     u32 num_flashes;
>> +     struct altera_epcq_flash *flash[MAX_NUM_FLASH_CHIP];
>> +};
>> +
>> +struct altera_epcq_flash {
>> +     u32 bank;
>> +     u32 num_sectors;
>> +     u32 num_parts;
>> +     struct mtd_partition *parts;
>> +     struct mutex lock;      /*flash lock*/
>> +     struct mtd_info mtd;
>> +};
>> +
>> +/* Define max times to check status register before we give up. */
>> +#define EPCQ_MAX_TIME_OUT                    (40 * HZ)
>> +
>> +/* defines for status register */
>> +#define EPCQ_SR_REG                          0x0
>> +#define EPCQ_SR_WIP_MASK                     0x00000001
>> +#define EPCQ_SR_WIP                          0x1
>> +#define EPCQ_SR_WEL                          0x2
>> +#define EPCQ_SR_BP0                          0x4
>> +#define EPCQ_SR_BP1                          0x8
>> +#define EPCQ_SR_BP2                          0x10
>> +#define EPCQ_SR_BP3                          0x40
>> +#define EPCQ_SR_TB                           0x20
>> +
>> +/* defines for device id register */
>> +#define EPCQ_SID_REG                         0x4
>> +#define EPCQ_RDID_REG                                0x8
>> +#define EPCQ_RDID_MASK                               0x000000FF
>> +/*
>> + * EPCQ_MEM_OP register offset
>> + *
>> + * The EPCQ_MEM_OP register is used to do memory protect and erase operations
>> + *
>> + */
>> +#define EPCQ_MEM_OP_REG                              0xC
>> +
>> +#define EPCQ_MEM_OP_CMD_MASK                 0x00000003
>> +#define EPCQ_MEM_OP_BULK_ERASE_CMD           0x00000001
>> +#define EPCQ_MEM_OP_SECTOR_ERASE_CMD         0x00000002
>> +#define EPCQ_MEM_OP_SECTOR_PROTECT_CMD               0x00000003
>> +#define EPCQ_MEM_OP_SECTOR_VALUE_MASK                0x0003FF00
>> +#define EPCQ_MEM_OP_SECTOR_PROTECT_VALUE_MASK        0x00001F00
>> +#define EPCQ_MEM_OP_SECTOR_PROTECT_SHIFT     8
>> +/*
>> + * EPCQ_ISR register offset
>> + *
>> + * The EPCQ_ISR register is used to determine whether an invalid write or erase
>> + * operation trigerred an interrupt
>> + *
>> + */
>> +#define EPCQ_ISR_REG                         0x10
>> +
>> +#define EPCQ_ISR_ILLEGAL_ERASE_MASK          0x00000001
>> +#define EPCQ_ISR_ILLEGAL_WRITE_MASK          0x00000002
>> +
>> +/*
>> + * EPCQ_IMR register offset
>> + *
>> + * The EPCQ_IMR register is used to mask the invalid erase or the invalid write
>> + * interrupts.
>> + *
>> + */
>> +#define EPCQ_IMR_REG                         0x14
>> +#define EPCQ_IMR_ILLEGAL_ERASE_MASK          0x00000001
>> +
>> +#define EPCQ_IMR_ILLEGAL_WRITE_MASK          0x00000002
>> +
>> +#define EPCQ_CHIP_SELECT_REG                 0x18
>> +#define EPCQ_CHIP_SELECT_MASK                        0x00000007
>> +#define EPCQ_CHIP_SELECT_0                   0x00000001
>> +#define EPCQ_CHIP_SELECT_1                   0x00000002
>> +#define EPCQ_CHIP_SELECT_2                   0x00000004
>> +
>> +#endif /* __ALTERA_ECPQ_H */
>
> Brian
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