Re: [PATCH v3 char-misc-next] misc: microchip: pci1xxxx: Add OTP/EEPROM driver for the pci1xxxx switch

[Greg KH <gregkh@xxxxxxxxxxxxxxxxxxx>]

On Tue, Jan 17, 2023 at 12:59:07AM +0530, Kumaravel Thiagarajan wrote:
> Microchip's pci1xxxx is an unmanaged PCIe3.1a switch for consumer, industrial,
> and automotive applications. This switch integrates OTP and EEPROM to enable
> customization of the part in the field. This patch provides the OTP/EEPROM
> driver to support the same.
> 
> This patch also fixes build issue reported by kernel test robot <lkp@xxxxxxxxx>
> on v1 version of patch.
> Following are some of the build issues reported which are fixed in this patch:
>     >> ld.lld: error: undefined symbol: blk_mq_alloc_tag_set
>     >> ld.lld: error: undefined symbol: blk_mq_init_queue
>     >> ld.lld: error: undefined symbol: blk_mq_free_tag_set
>     >> ld.lld: error: undefined symbol: blk_mq_start_request
>     >> ld.lld: error: undefined symbol: blk_mq_end_request
>     >> ld.lld: error: undefined symbol: unregister_blkdev
>     >> ld.lld: error: undefined symbol: __register_blkdev
>     >> ld.lld: error: undefined symbol: blk_queue_logical_block_size
>     >> ld.lld: error: undefined symbol: blk_queue_physical_block_size
>     >> ld.lld: error: undefined symbol: __blk_mq_alloc_disk
>     >> ld.lld: error: undefined symbol: set_capacity
> 
> Reported-by: kernel test robot <lkp@xxxxxxxxx>

Note, the kernel test robot did not report the need for a new driver
here, so it's not really relevant for this changelog (nor is the error
fixes as obviously you would only submit a working driver...)

So when you submit the next version, please remove.

Review comments below:

> Co-developed-by: Tharun Kumar P <tharunkumar.pasumarthi@xxxxxxxxxxxxx>
> Signed-off-by: Tharun Kumar P <tharunkumar.pasumarthi@xxxxxxxxxxxxx>
> Signed-off-by: Kumaravel Thiagarajan <kumaravel.thiagarajan@xxxxxxxxxxxxx>
> ---
> v2 -> v3:
> - Modified commit description to include build issues reported by Kernel
> test robot <lkp@xxxxxxxxx> which are fixed in this patch
> 
> v1 -> v2:
> - Resolve build issue reported by kernel test robot <lkp@xxxxxxxxx>
> ---
>  MAINTAINERS                                   |   1 +
>  drivers/misc/mchp_pci1xxxx/Kconfig            |   1 +
>  drivers/misc/mchp_pci1xxxx/Makefile           |   2 +-
>  .../misc/mchp_pci1xxxx/mchp_pci1xxxx_otpe2p.c | 693 ++++++++++++++++++
>  4 files changed, 696 insertions(+), 1 deletion(-)
>  create mode 100644 drivers/misc/mchp_pci1xxxx/mchp_pci1xxxx_otpe2p.c
> 
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 9886aa1a4403..195af3ac451d 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -13614,6 +13614,7 @@ S:	Supported
>  F:	drivers/misc/mchp_pci1xxxx/mchp_pci1xxxx_gp.c
>  F:	drivers/misc/mchp_pci1xxxx/mchp_pci1xxxx_gp.h
>  F:	drivers/misc/mchp_pci1xxxx/mchp_pci1xxxx_gpio.c
> +F:	drivers/misc/mchp_pci1xxxx/mchp_pci1xxxx_otpe2p.c
>  
>  MICROCHIP OTPC DRIVER
>  M:	Claudiu Beznea <claudiu.beznea@xxxxxxxxxxxxx>
> diff --git a/drivers/misc/mchp_pci1xxxx/Kconfig b/drivers/misc/mchp_pci1xxxx/Kconfig
> index 4abb47de7219..67fa3299cfb6 100644
> --- a/drivers/misc/mchp_pci1xxxx/Kconfig
> +++ b/drivers/misc/mchp_pci1xxxx/Kconfig
> @@ -2,6 +2,7 @@ config GP_PCI1XXXX
>         tristate "Microchip PCI1XXXX PCIe to GPIO Expander + OTP/EEPROM manager"
>         depends on PCI
>         depends on GPIOLIB
> +       depends on BLOCK
>         select GPIOLIB_IRQCHIP
>         select AUXILIARY_BUS
>         help
> diff --git a/drivers/misc/mchp_pci1xxxx/Makefile b/drivers/misc/mchp_pci1xxxx/Makefile
> index fc4615cfe28b..ae31251dab37 100644
> --- a/drivers/misc/mchp_pci1xxxx/Makefile
> +++ b/drivers/misc/mchp_pci1xxxx/Makefile
> @@ -1 +1 @@
> -obj-$(CONFIG_GP_PCI1XXXX) := mchp_pci1xxxx_gp.o mchp_pci1xxxx_gpio.o
> +obj-$(CONFIG_GP_PCI1XXXX) := mchp_pci1xxxx_gp.o mchp_pci1xxxx_gpio.o mchp_pci1xxxx_otpe2p.o
> diff --git a/drivers/misc/mchp_pci1xxxx/mchp_pci1xxxx_otpe2p.c b/drivers/misc/mchp_pci1xxxx/mchp_pci1xxxx_otpe2p.c
> new file mode 100644
> index 000000000000..03a537d45873
> --- /dev/null
> +++ b/drivers/misc/mchp_pci1xxxx/mchp_pci1xxxx_otpe2p.c
> @@ -0,0 +1,693 @@
> +// SPDX-License-Identifier: GPL-2.0
> +// Copyright (C) 2023 Microchip Technology Inc.
> +// PCI1xxxx OTP/EEPROM driver
> +
> +#include <linux/auxiliary_bus.h>
> +#include <linux/bio.h>
> +#include <linux/blkdev.h>
> +#include <linux/blk-mq.h>
> +#include <linux/delay.h>
> +#include <linux/gpio/driver.h>
> +#include <linux/kthread.h>
> +#include <linux/module.h>
> +#include <linux/mutex.h>
> +#include <linux/spinlock.h>
> +
> +#include "mchp_pci1xxxx_gp.h"
> +
> +#define PERI_PF3_SYSTEM_REG_ADDR_BASE	(0x2000)
> +#define PERI_PF3_SYSTEM_REG_LENGTH	(0x4000)
> +
> +#define CONFIG_REG_ADDR_BASE		(0)
> +#define EEPROM_REG_ADDR_BASE		(0x0E00)
> +#define OTP_REG_ADDR_BASE		(0x1000)
> +
> +#define MMAP_CFG_OFFSET(x)		(CONFIG_REG_ADDR_BASE + (x))
> +
> +#define CFG_SYS_LOCK_OFFSET		(0xA0)
> +#define CFG_SYS_LOCK_PF3		BIT(5)
> +
> +#define MMAP_OTP_OFFSET(x)		(OTP_REG_ADDR_BASE + (x))
> +
> +#define OTP_PWR_DN_OFFSET		(0x00)
> +#define OTP_ADDR_HIGH_OFFSET		(0x04)
> +#define OTP_ADDR_LOW_OFFSET		(0x08)
> +#define	OTP_ADDR_BITS_OFFSET		(0x0C)

Extra tab used here after "define", please don't.

> +#define OTP_PRGM_DATA_OFFSET		(0x10)
> +#define OTP_PRGM_MODE_OFFSET		(0x14)
> +#define OTP_RD_DATA_OFFSET		(0x18)
> +#define OTP_FUNC_CMD_OFFSET		(0x20)
> +#define OTP_TEST_CMD_OFFSET		(0x24)
> +#define OTP_CMD_GO_OFFSET		(0x28)
> +#define OTP_PASS_FAIL_OFFSET		(0x2C)
> +#define OTP_STATUS_OFFSET		(0x30)
> +#define OTP_MAX_PRG_OFFSET		(0x34)
> +#define OTP_RSTB_PW_OFFSET		(0x50)
> +#define OTP_PGM_PW_OFFSET		(0x60)
> +#define OTP_READ_PW_OFFSET		(0x70)
> +
> +#define OTP_PWR_DN_BIT			BIT(0)
> +#define OTP_CMD_GO_BIT			BIT(0)
> +#define OTP_PGM_MODE_BYTE_BIT		BIT(0)
> +#define OTP_STATUS_BUSY_BIT		BIT(0)
> +#define OTP_FUNC_PGM_BIT		BIT(1)
> +#define OTP_FUNC_RD_BIT			BIT(0)
> +
> +#define OTP_RW_TIMEOUT_MILLISECONDS	(5)
> +
> +#define MMAP_EEPROM_OFFSET(x)		(EEPROM_REG_ADDR_BASE + (x))
> +
> +#define E2P_CMD_REG			(0x00)
> +#define E2P_DATA_REG			(0x04)
> +#define E2P_CFG_REG			(0x08)
> +#define E2P_PAD_CTL_REG			(0x0C)
> +
> +#define E2P_CMD_EPC_BUSY_BIT		BIT(31)
> +#define E2P_CMD_EPC_TIMEOUT_BIT		BIT(17)
> +#define E2P_CMD_EPC_WRITE		(BIT(29) | BIT(28))
> +
> +#define E2P_CFG_BAUD_RATE_100KHZ	BIT(9)
> +#define E2P_CFG_SIZE_SEL		BIT(12)
> +#define E2P_CFG_PULSE_WIDTH_100KHZ	(BIT(17) | BIT(16))
> +#define OTP_E2P_SECTOR_SIZE		(512)
> +#define OTP_SIZE_IN_BYTES		(8 * 1024)
> +#define E2P_SIZE_IN_BYTES		(8 * 1024)
> +
> +struct pci1xxxx_otp_e2p_device {
> +	struct pci1xxxx_otp_e2p_disk *otp_e2p_device;
> +	struct auxiliary_device *pdev;
> +	void __iomem *reg_base;
> +	int block_device_count;
> +};
> +
> +struct pci1xxxx_otp_e2p_disk {
> +	struct blk_mq_tag_set tag_set;
> +	struct auxiliary_device *pdev;
> +	struct request_queue *queue;
> +	struct mutex  lock;

Odd extra space?

> +	struct gendisk *gd;
> +	bool E2P;

What is "E2P"?  Spell it out as a lower case variable.

> +	int (*disk_write_byte)(struct pci1xxxx_otp_e2p_device *priv,
> +		unsigned long byte_offset, u8 value);
> +	int (*disk_read_byte)(struct pci1xxxx_otp_e2p_device *priv,
> +		unsigned long byte_offset, u8 *data);
> +};
> +
> +static int OTP_sector_count = OTP_SIZE_IN_BYTES / OTP_E2P_SECTOR_SIZE;
> +static int E2P_sector_count = E2P_SIZE_IN_BYTES / OTP_E2P_SECTOR_SIZE;

Linux kernel style is all lower case please, "otp_sector_count",
"e2p_sector_count".

> +static int otp_device_count, e2p_device_count;

See, you do that here just fine.

> +static int block_driver_registered;

Do you really need this?  How can that happen that this is ever not
true?

> +static int OTP_block_driver_major;

Again, lower case please.


> +
> +static void otp_device_set_address(struct pci1xxxx_otp_e2p_device *priv, u16 address)
> +{
> +	u32 lo, hi;
> +
> +	lo = address & 0xFF;
> +	hi = (address & 0x1f00) >> 8;
> +	writel(lo, priv->reg_base + MMAP_OTP_OFFSET(OTP_ADDR_LOW_OFFSET));
> +	writel(hi, priv->reg_base + MMAP_OTP_OFFSET(OTP_ADDR_HIGH_OFFSET));
> +}
> +
> +static int set_sys_lock(struct pci1xxxx_otp_e2p_device *priv)
> +{
> +	void __iomem *p = priv->reg_base + MMAP_CFG_OFFSET(CFG_SYS_LOCK_OFFSET);
> +	u8 data;
> +
> +	writel(CFG_SYS_LOCK_PF3, p);
> +	data = readl(p);
> +	if (data != CFG_SYS_LOCK_PF3)
> +		return -EPERM;
> +
> +	return 0;
> +}
> +
> +static int release_sys_lock(struct pci1xxxx_otp_e2p_device *priv)
> +{
> +	void __iomem *p = priv->reg_base + MMAP_CFG_OFFSET(CFG_SYS_LOCK_OFFSET);
> +	u8 data;
> +
> +	data = readl(p);
> +	if (data != CFG_SYS_LOCK_PF3)
> +		return 0;
> +
> +	writel(0, p);
> +
> +	data = readl(p);
> +	if (data & CFG_SYS_LOCK_PF3)
> +		return -EPERM;
> +
> +	return 0;
> +}
> +
> +static int otp_e2p_device_open(struct block_device *bdev, fmode_t mode)
> +{
> +	struct pci1xxxx_otp_e2p_disk *disk_priv;
> +	struct pci1xxxx_otp_e2p_device *priv;
> +	struct auxiliary_device *pdev;
> +	int retval = 0;
> +	u8 data;
> +
> +	disk_priv = (struct pci1xxxx_otp_e2p_disk *)bdev->bd_disk->private_data;
> +	pdev = (struct auxiliary_device *)disk_priv->pdev;
> +	priv = dev_get_drvdata(&pdev->dev);
> +
> +	mutex_lock(&disk_priv->lock);
> +
> +	do {
> +		retval = set_sys_lock(priv);
> +		if (retval)
> +			break;
> +
> +		if (!disk_priv->E2P) {
> +			data = readl(priv->reg_base +
> +				     MMAP_OTP_OFFSET(OTP_PWR_DN_OFFSET));
> +			writel((data & ~OTP_PWR_DN_BIT), priv->reg_base +
> +				MMAP_OTP_OFFSET(OTP_PWR_DN_OFFSET));
> +		}
> +	} while (false);

Why do you have these odd do {} while (false); blocks in the driver?
They are not needed at all, just jump to the exit location please.
That's the normal kernel coding style, not this way.

> +
> +	mutex_unlock(&disk_priv->lock);
> +
> +	return retval;
> +}
> +
> +static void otp_e2p_device_release(struct gendisk *disk, fmode_t mode)
> +{
> +	struct pci1xxxx_otp_e2p_disk *disk_priv;
> +	struct pci1xxxx_otp_e2p_device *priv;
> +	u8 data;
> +
> +	disk_priv = (struct pci1xxxx_otp_e2p_disk *)disk->private_data;

No need for cast.  You do that in a lot of places.

> +	priv = dev_get_drvdata(&disk_priv->pdev->dev);
> +
> +	mutex_lock(&disk_priv->lock);
> +
> +	if (!disk_priv->E2P) {
> +		data = readl(priv->reg_base + MMAP_OTP_OFFSET(OTP_PWR_DN_OFFSET));
> +		writel((data | OTP_PWR_DN_BIT), priv->reg_base +
> +			MMAP_OTP_OFFSET(OTP_PWR_DN_OFFSET));
> +	}
> +	release_sys_lock(priv);
> +
> +	mutex_unlock(&disk_priv->lock);
> +}
> +
> +static int e2p_device_write_byte(struct pci1xxxx_otp_e2p_device *priv,
> +				 unsigned long byte_offset, u8 value)
> +{
> +	u32 data;
> +
> +	/* Write the value into E2P_DATA_REG register */
> +	writel(value, priv->reg_base + MMAP_EEPROM_OFFSET(E2P_DATA_REG));
> +	data = E2P_CMD_EPC_TIMEOUT_BIT | E2P_CMD_EPC_WRITE | byte_offset;
> +
> +	/* Write the data into E2P_CMD_REG register */
> +	writel(data, priv->reg_base + MMAP_EEPROM_OFFSET(E2P_CMD_REG));
> +
> +	/* Set the EPC_BUSY bit of E2P_CMD_REG register */
> +	writel(E2P_CMD_EPC_BUSY_BIT | data, priv->reg_base +
> +	       MMAP_EEPROM_OFFSET(E2P_CMD_REG));
> +
> +	/* Wait for the EPC_BUSY bit to get cleared */
> +	do {
> +		data = readl(priv->reg_base + MMAP_EEPROM_OFFSET(E2P_CMD_REG));
> +	} while (data & E2P_CMD_EPC_BUSY_BIT);
> +
> +	if (data & E2P_CMD_EPC_TIMEOUT_BIT) {
> +		dev_err(&priv->pdev->dev, "%s timed out\n", __func__);
> +		return -EFAULT;
> +	}
> +
> +	return 0;
> +}
> +
> +static int e2p_device_read_byte(struct pci1xxxx_otp_e2p_device *priv,
> +				unsigned long byte_offset, u8 *data)
> +{
> +	u32 regval;
> +
> +	/*
> +	 * Write the byte offset into the EPC_ADDRESS field of E2P_CMD_REG
> +	 * register
> +	 */
> +	writel(byte_offset, priv->reg_base + MMAP_EEPROM_OFFSET(E2P_CMD_REG));
> +
> +	/* Set the EPC_BUSY bit of E2P_CMD_REG register */
> +	writel(E2P_CMD_EPC_BUSY_BIT | byte_offset, priv->reg_base +
> +	       MMAP_EEPROM_OFFSET(E2P_CMD_REG));
> +
> +	/* Wait for the EPC_BUSY bit to get cleared */
> +	do {
> +		regval = readl(priv->reg_base + MMAP_EEPROM_OFFSET(E2P_CMD_REG));
> +	} while (regval & E2P_CMD_EPC_BUSY_BIT);
> +
> +	if (regval & E2P_CMD_EPC_TIMEOUT_BIT) {
> +		dev_err(&priv->pdev->dev, "%s timed out\n", __func__);
> +		return -EFAULT;
> +	}
> +
> +	/* Read the contents from the E2P_DATA_REG */
> +	*data = readl(priv->reg_base + MMAP_EEPROM_OFFSET(E2P_DATA_REG));
> +	return 0;
> +}
> +
> +static bool check_e2p_response(struct pci1xxxx_otp_e2p_device *priv)

So false is "response is good?"  Or bad?  It's not obvious here at all.

> +{
> +	u32 data;
> +
> +	if (set_sys_lock(priv))
> +		return false;
> +
> +	writel((E2P_CFG_PULSE_WIDTH_100KHZ | E2P_CFG_SIZE_SEL |
> +		E2P_CFG_BAUD_RATE_100KHZ), priv->reg_base +
> +		MMAP_EEPROM_OFFSET(E2P_CFG_REG));
> +
> +	/*
> +	 * Write the byte offset into the EPC_ADDRESS field of E2P_CMD_REG
> +	 * register
> +	 */
> +	writel(E2P_CMD_EPC_TIMEOUT_BIT, priv->reg_base +
> +	       MMAP_EEPROM_OFFSET(E2P_CMD_REG));
> +
> +	/* Set the EPC_BUSY bit of E2P_CMD_REG register */
> +	writel(E2P_CMD_EPC_BUSY_BIT, priv->reg_base +
> +	       MMAP_EEPROM_OFFSET(E2P_CMD_REG));
> +
> +	/* Wait for the EPC_BUSY bit to get cleared or timeout bit to get set*/
> +	do {
> +		data = readl(priv->reg_base + MMAP_EEPROM_OFFSET(E2P_CMD_REG));
> +	} while (data & E2P_CMD_EPC_BUSY_BIT);
> +
> +	/* If EPC_TIMEOUT is set, then the EEPROM is not responsive */
> +	release_sys_lock(priv);
> +
> +	if (data & E2P_CMD_EPC_TIMEOUT_BIT) {
> +		dev_err(&priv->pdev->dev,
> +			"EPC_Timeout, EEPROM is unresponsive: %x\n", data);

Can this spam the kernel logs?  If so, please rate limit it.

> +		return false;
> +	}
> +
> +	return true;
> +}
> +
> +static int otp_device_write_byte(struct pci1xxxx_otp_e2p_device *priv,
> +				 unsigned long byte_offset, u8 value)
> +{
> +	unsigned long j0, j1, delay;
> +	u8 data;
> +
> +	if (!value)
> +		return 0;
> +
> +	otp_device_set_address(priv, (u16)byte_offset);
> +
> +	/* Set OTP_PGM_MODE_BYTE command bit in OTP_PRGM_MODE register */
> +	data = readl(priv->reg_base + MMAP_OTP_OFFSET(OTP_PRGM_MODE_OFFSET));
> +	writel((data | OTP_PGM_MODE_BYTE_BIT), priv->reg_base +
> +		MMAP_OTP_OFFSET(OTP_PRGM_MODE_OFFSET));
> +
> +	/* Write the value to program into OTP_PRGM_DATA register */
> +	writel(value, priv->reg_base + MMAP_OTP_OFFSET(OTP_PRGM_DATA_OFFSET));
> +
> +	/* Set OTP_PROGRAM command bit in OTP_FUNC_CMD register */
> +	data = readl(priv->reg_base + MMAP_OTP_OFFSET(OTP_FUNC_CMD_OFFSET));
> +	writel((data | OTP_FUNC_PGM_BIT), priv->reg_base +
> +		MMAP_OTP_OFFSET(OTP_FUNC_CMD_OFFSET));
> +
> +	/* Set OTP_GO command bit in OTP_CMD_GO register */
> +	data = readl(priv->reg_base + MMAP_OTP_OFFSET(OTP_CMD_GO_OFFSET));
> +	writel((data | OTP_CMD_GO_BIT), priv->reg_base +
> +		MMAP_OTP_OFFSET(OTP_CMD_GO_OFFSET));
> +	delay = msecs_to_jiffies(OTP_RW_TIMEOUT_MILLISECONDS);
> +	j0 = jiffies;
> +	j1 = j0 + delay;

Are you sure this math works out?  Please use the jiffies math functions
instead so you can handle wrapping properly.

> +
> +	/* Wait for the OTP_BUSY bit to get cleared in OTP_STATUS register */
> +	do {
> +		data = readl(priv->reg_base + MMAP_OTP_OFFSET(OTP_STATUS_OFFSET));
> +	} while ((data & OTP_STATUS_BUSY_BIT) && (time_before(jiffies, j1)));
> +
> +	if (data & OTP_STATUS_BUSY_BIT) {
> +		dev_err(&priv->pdev->dev, "%s timed out\n", __func__);
> +		return -EFAULT;
> +	}
> +
> +	/* Read the result from OTP_RD_DATA register */
> +	data = readl(priv->reg_base + MMAP_OTP_OFFSET(OTP_PASS_FAIL_OFFSET));
> +	if (data & 0x02)
> +		return 0;
> +
> +	dev_err(&priv->pdev->dev, "%s write read mismatch 0x%x\n", __func__, data);

No need for any __func__ usage in any print messages please.  dev_dbg()
will give you that for free, and any normal message will not need it as
it is obvious what driver/device it came from.

> +	return -EFAULT;
> +}
> +
> +static int otp_device_read_byte(struct pci1xxxx_otp_e2p_device *priv,
> +				unsigned long byte_offset, u8 *data)
> +{
> +	unsigned long j0, j1, delay;
> +
> +	otp_device_set_address(priv, (u16)byte_offset);
> +
> +	/* Set OTP_READ command bit in OTP_FUNC_CMD register */
> +	*data = readl(priv->reg_base + MMAP_OTP_OFFSET(OTP_FUNC_CMD_OFFSET));
> +	writel((*data | OTP_FUNC_RD_BIT), priv->reg_base +
> +		MMAP_OTP_OFFSET(OTP_FUNC_CMD_OFFSET));
> +
> +	/* Set OTP_GO command bit in OTP_CMD_GO register */
> +	*data = readl(priv->reg_base + MMAP_OTP_OFFSET(OTP_CMD_GO_OFFSET));
> +	writel((*data | OTP_CMD_GO_BIT), priv->reg_base +
> +		MMAP_OTP_OFFSET(OTP_CMD_GO_OFFSET));
> +	delay = msecs_to_jiffies(OTP_RW_TIMEOUT_MILLISECONDS);
> +	j0 = jiffies;
> +	j1 = j0 + delay;
> +
> +	/* Wait for OTP_BUSY bit to get cleared in OTP_STATUS */
> +	do {
> +		*data = readl(priv->reg_base + MMAP_OTP_OFFSET(OTP_STATUS_OFFSET));
> +	} while ((*data & OTP_STATUS_BUSY_BIT) && (time_before(jiffies, j1)));
> +
> +	if (*data & OTP_STATUS_BUSY_BIT) {
> +		dev_err(&priv->pdev->dev, "%s timed out\n", __func__);
> +		return -EFAULT;
> +	}
> +
> +	/* Read the result from OTP_RD_DATA register */
> +	*data = readl(priv->reg_base + MMAP_OTP_OFFSET(OTP_RD_DATA_OFFSET));
> +	return 0;
> +}
> +
> +static int otp_e2P_device_transfer(struct request *req)
> +{
> +	struct pci1xxxx_otp_e2p_disk *disk_priv;
> +	struct pci1xxxx_otp_e2p_device *priv;
> +	unsigned long sector;
> +	unsigned long nsect;
> +	long byte_offset;
> +	int retval;
> +	u8 *buffer;
> +	int write;
> +	int i, j;
> +
> +	sector = blk_rq_pos(req);
> +	nsect = blk_rq_cur_sectors(req);
> +	buffer = bio_data(req->bio);
> +	write = rq_data_dir(req);
> +	disk_priv = (struct pci1xxxx_otp_e2p_disk *)req->q->disk->private_data;
> +	priv = dev_get_drvdata(&disk_priv->pdev->dev);
> +
> +	if (write) {
> +		for (i = 0; i < nsect; i++) {
> +			byte_offset = (sector + i) * OTP_E2P_SECTOR_SIZE;
> +			for (j = 0; j < OTP_E2P_SECTOR_SIZE; j++) {
> +				retval = disk_priv->disk_write_byte(priv,
> +								    byte_offset + j,
> +								    *buffer);
> +				if (retval)
> +					return retval;
> +
> +				buffer++;
> +			}
> +		}
> +	} else {
> +		for (i = 0; i < nsect; i++) {
> +			byte_offset = (sector + i) * OTP_E2P_SECTOR_SIZE;
> +			for (j = 0; j < OTP_E2P_SECTOR_SIZE; j++) {
> +				retval = disk_priv->disk_read_byte(priv,
> +								   byte_offset + j,
> +								   buffer);
> +				if (retval)
> +					return retval;
> +
> +				buffer++;
> +			}
> +		}
> +	}
> +
> +	return 0;
> +}
> +
> +static blk_status_t OTPE2P_queue_rq(struct blk_mq_hw_ctx *hctx,
> +				    const struct blk_mq_queue_data *bd)
> +{
> +	struct request *req = bd->rq;
> +
> +	blk_mq_start_request(req);
> +	if (!otp_e2P_device_transfer(req)) {
> +		blk_mq_end_request(req, BLK_STS_OK);
> +		return BLK_STS_OK;
> +	}
> +
> +	return BLK_STS_IOERR;
> +}
> +
> +static const struct blk_mq_ops OTPE2P_mq_ops = {
> +	.queue_rq	= OTPE2P_queue_rq,
> +};
> +
> +static const struct block_device_operations otp_e2p_device_ops = {
> +	.owner = THIS_MODULE,
> +	.open = otp_e2p_device_open,
> +	.release = otp_e2p_device_release,
> +};
> +
> +static int otp_e2p_device_create_block_device(struct auxiliary_device *aux_dev)
> +{
> +	struct auxiliary_device_wrapper *aux_dev_wrapper;
> +	struct pci1xxxx_otp_e2p_device *priv;
> +	struct gp_aux_data_type *pdata;
> +	int retval = 0, i;
> +
> +	aux_dev_wrapper = (struct auxiliary_device_wrapper *) container_of(aux_dev,
> +			  struct auxiliary_device_wrapper, aux_dev);

No need to cast your container_of() call.

> +	pdata = &(aux_dev_wrapper->gp_aux_data);

No need for ()

> +	if (!pdata) {
> +		dev_err(&aux_dev->dev, "Invalid data in aux_dev_wrapper->gp_aux_data\n");
> +		return -EINVAL;
> +	}
> +
> +	priv = devm_kzalloc(&aux_dev->dev, sizeof(struct pci1xxxx_otp_e2p_device),
> +			    GFP_KERNEL);
> +	if (!priv)
> +		return -ENOMEM;
> +
> +	priv->pdev = aux_dev;
> +
> +	dev_set_drvdata(&aux_dev->dev, priv);
> +
> +	if (!devm_request_mem_region(&aux_dev->dev, pdata->region_start +
> +				     PERI_PF3_SYSTEM_REG_ADDR_BASE,
> +		PERI_PF3_SYSTEM_REG_LENGTH, aux_dev->name)) {
> +		dev_err(&aux_dev->dev, "can't request otpe2p region\n");
> +		return -ENOMEM;
> +	}
> +
> +	priv->reg_base = devm_ioremap(&aux_dev->dev, pdata->region_start +
> +				      PERI_PF3_SYSTEM_REG_ADDR_BASE,
> +				      PERI_PF3_SYSTEM_REG_LENGTH);
> +	if (!priv->reg_base) {
> +		dev_err(&aux_dev->dev, "ioremap failed\n");
> +		return -ENOMEM;
> +	}
> +
> +	priv->block_device_count = 0;
> +	do {
> +		if (check_e2p_response(priv))
> +			priv->block_device_count = 2;
> +		else
> +			priv->block_device_count = 1;
> +
> +		priv->otp_e2p_device = devm_kzalloc(&priv->pdev->dev,
> +						    priv->block_device_count *
> +						    sizeof(struct pci1xxxx_otp_e2p_disk),
> +						    GFP_KERNEL);
> +		if (!priv->otp_e2p_device) {
> +			retval = -ENOMEM;
> +			break;
> +		}
> +
> +		for (i = 0; i < priv->block_device_count; i++) {
> +			mutex_init(&priv->otp_e2p_device[i].lock);
> +			priv->otp_e2p_device[i].tag_set.ops = &OTPE2P_mq_ops;
> +			priv->otp_e2p_device[i].tag_set.nr_hw_queues = 1;
> +			priv->otp_e2p_device[i].tag_set.queue_depth = 16;
> +			priv->otp_e2p_device[i].tag_set.flags = BLK_MQ_F_SHOULD_MERGE;
> +
> +			retval = blk_mq_alloc_tag_set(&priv->otp_e2p_device[i].tag_set);
> +			if (retval) {
> +				dev_err(&aux_dev->dev, "blk_mq_alloc_tag_set failed\n");
> +				break;
> +			}
> +
> +			priv->otp_e2p_device[i].queue =
> +				blk_mq_init_queue(&priv->otp_e2p_device[i].tag_set);
> +			if (IS_ERR(priv->otp_e2p_device[i].queue)) {
> +				retval = PTR_ERR(priv->otp_e2p_device[i].queue);
> +				priv->otp_e2p_device[i].queue = NULL;
> +				if (i)
> +					goto e2p_free_tag_set;
> +				else
> +					goto otp_free_tag_set;
> +			}
> +
> +			blk_queue_logical_block_size(priv->otp_e2p_device[i].queue,
> +						     OTP_E2P_SECTOR_SIZE);
> +			blk_queue_physical_block_size(priv->otp_e2p_device[i].queue,
> +						      OTP_E2P_SECTOR_SIZE);
> +			priv->otp_e2p_device[i].queue->queuedata = priv;
> +			priv->otp_e2p_device[i].gd =
> +				blk_mq_alloc_disk(&priv->otp_e2p_device[i].tag_set,
> +				NULL);
> +			if (IS_ERR(priv->otp_e2p_device[i].gd)) {
> +				retval = PTR_ERR(priv->otp_e2p_device[i].gd);
> +				if (i)
> +					goto e2p_destroy_queue;
> +				else
> +					goto otp_destroy_queue;
> +			}
> +
> +			priv->otp_e2p_device[i].pdev = aux_dev;
> +			priv->otp_e2p_device[i].gd->major = OTP_block_driver_major;
> +			priv->otp_e2p_device[i].gd->minors = 1;
> +			priv->otp_e2p_device[i].gd->first_minor =
> +				otp_device_count + e2p_device_count;
> +			priv->otp_e2p_device[i].gd->fops = &otp_e2p_device_ops;
> +			priv->otp_e2p_device[i].gd->private_data =
> +				&priv->otp_e2p_device[i];
> +
> +			if (i == 0) {
> +				snprintf(priv->otp_e2p_device[i].gd->disk_name,
> +					 32, "PCI1xxxxOTP%x", otp_device_count);
> +				set_capacity(priv->otp_e2p_device[i].gd,
> +					     OTP_sector_count);
> +				priv->otp_e2p_device[i].disk_read_byte = otp_device_read_byte;
> +				priv->otp_e2p_device[i].disk_write_byte = otp_device_write_byte;
> +				otp_device_count++;
> +			} else {
> +				snprintf(priv->otp_e2p_device[i].gd->disk_name,
> +					 32, "PCI1xxxxE2P%x", otp_device_count - 1);
> +				set_capacity(priv->otp_e2p_device[i].gd,
> +					     E2P_sector_count);
> +				priv->otp_e2p_device[i].E2P = true;
> +				priv->otp_e2p_device[i].disk_read_byte = e2p_device_read_byte;
> +				priv->otp_e2p_device[i].disk_write_byte = e2p_device_write_byte;
> +				e2p_device_count++;
> +			}
> +
> +			retval = add_disk(priv->otp_e2p_device[i].gd);
> +			if (retval) {
> +				if (i)
> +					goto e2p_free_disk;
> +				else
> +					goto otp_free_disk;
> +			}
> +		}
> +
> +	} while (false);

Again, drop the do {} while (false); block logic as it will simplify
this code (you are already doing gotos...)

> +
> +	return retval;
> +
> +e2p_free_disk:
> +	del_gendisk(priv->otp_e2p_device[1].gd);
> +	put_disk(priv->otp_e2p_device[1].gd);
> +e2p_destroy_queue:
> +	blk_mq_destroy_queue(priv->otp_e2p_device[1].queue);
> +e2p_free_tag_set:
> +	blk_mq_free_tag_set(&priv->otp_e2p_device[1].tag_set);
> +otp_free_disk:
> +	del_gendisk(priv->otp_e2p_device[0].gd);
> +	put_disk(priv->otp_e2p_device[0].gd);
> +otp_destroy_queue:
> +	blk_mq_destroy_queue(priv->otp_e2p_device[0].queue);
> +otp_free_tag_set:
> +	blk_mq_free_tag_set(&priv->otp_e2p_device[0].tag_set);
> +
> +	return retval;
> +}
> +
> +static void pci1xxxx_otp_e2p_remove(struct auxiliary_device *aux_dev)
> +{
> +	struct pci1xxxx_otp_e2p_device *priv = dev_get_drvdata(&aux_dev->dev);
> +	int i;
> +
> +	for (i = 0; i < priv->block_device_count; i++) {
> +

No blank line needed (yeah, I'm getting picky, sorry.)

> +		if (priv->otp_e2p_device[i].queue)
> +			blk_mq_destroy_queue(priv->otp_e2p_device[i].queue);
> +
> +		if (priv->otp_e2p_device[i].gd) {
> +			del_gendisk(priv->otp_e2p_device[i].gd);
> +			put_disk(priv->otp_e2p_device[i].gd);
> +			blk_mq_free_tag_set(&priv->otp_e2p_device[i].tag_set);
> +		}
> +	}
> +}
> +
> +static int pci1xxxx_otp_e2p_probe(struct auxiliary_device *aux_dev,
> +				  const struct auxiliary_device_id *id)
> +{
> +	int retval;
> +
> +	retval = otp_e2p_device_create_block_device(aux_dev);
> +	if (retval) {
> +		dev_err(&aux_dev->dev,
> +			"otp/eeprom device enumeration failed with errno = %d\n",
> +			retval);

Why doesn't this function already return an error, now you have 2 error
messages, right?



> +		return retval;
> +	}
> +
> +	return 0;

This whole function can now be one line:
	return otp_e2p_device_create_block_device(aux_dev);

> +}
> +
> +static const struct auxiliary_device_id pci1xxxx_otp_e2p_auxiliary_id_table[] = {
> +	{.name = "mchp_pci1xxxx_gp.gp_otp_e2p"},
> +	{},
> +};
> +MODULE_DEVICE_TABLE(auxiliary, pci1xxxx_otp_e2p_auxiliary_id_table);
> +
> +static struct auxiliary_driver pci1xxxx_otp_e2p_driver = {
> +	.driver = {
> +		.name = "PCI1xxxxOTPE2P",
> +	},
> +	.probe = pci1xxxx_otp_e2p_probe,
> +	.remove = pci1xxxx_otp_e2p_remove,
> +	.id_table = pci1xxxx_otp_e2p_auxiliary_id_table
> +};
> +
> +static int __init pci1xxxx_otp_e2p_driver_init(void)
> +{
> +	int retval;
> +
> +	do {
> +		OTP_block_driver_major = register_blkdev(OTP_block_driver_major,
> +			"OTPBlockDevice");
> +		if (OTP_block_driver_major < 0) {
> +			retval = OTP_block_driver_major;
> +			break;
> +		}
> +
> +		block_driver_registered = 1;
> +
> +		retval = auxiliary_driver_register(&pci1xxxx_otp_e2p_driver);
> +		if (retval)
> +			break;

You just left the block device registered :(

> +
> +	} while (false);

Again, drop the do/while.

And again, the block_driver_registered variable is not needed as your
exit function will not be called if this function fails.

> +
> +	return retval;
> +}
> +
> +static void __exit pci1xxxx_otp_e2p_driver_exit(void)
> +{
> +	auxiliary_driver_unregister(&pci1xxxx_otp_e2p_driver);
> +	if (block_driver_registered)
> +		unregister_blkdev(OTP_block_driver_major, "OTPBlockDevice");

You need to unregister your block device _BEFORE_ the aux device goes
away underneath it :(

thanks,

greg k-h