Re: [PATCH] Input: add driver for Cypress APA I2C Trackpad

[Henrik Rydberg]

Hi Benson,

> This patch introduces a driver for Cypress All Points Addressable
> I2C Trackpad, including the one in the Samsung Series 5 550 Chromebook.
> 
> This device is compatible with MT protocol type B, providing identifiable
> contacts.
> 
> This driver also implements firmware updating capability via
> request_firmware.
> 
> Signed-off-by: Dudley Du <dudl@xxxxxxxxxxx>
> Signed-off-by: Benson Leung <bleung@xxxxxxxxxxxx>
> ---

Thanks for the driver, please find some comments inline.

>  drivers/input/mouse/Kconfig  |   13 +
>  drivers/input/mouse/Makefile |    1 +
>  drivers/input/mouse/cyapa.c  | 1493 ++++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 1507 insertions(+), 0 deletions(-)
>  create mode 100644 drivers/input/mouse/cyapa.c
> 
> diff --git a/drivers/input/mouse/Kconfig b/drivers/input/mouse/Kconfig
> index cd6268c..2767c3c 100644
> --- a/drivers/input/mouse/Kconfig
> +++ b/drivers/input/mouse/Kconfig
> @@ -193,6 +193,19 @@ config MOUSE_BCM5974
>  	  To compile this driver as a module, choose M here: the
>  	  module will be called bcm5974.
>  
> +config MOUSE_CYAPA
> +	tristate "Cypress APA I2C Trackpad support"
> +	depends on I2C
> +	help
> +	  This driver add support for Cypress All Points Addressable (APA)

"adds"

> +	  I2C Trackpads, including the one in the Samsung Series 5 550
> +	  Chromebook.
> +
> +	  Say Y here if you have a Cypress APA I2C Trackpad.
> +
> +	  To compile this driver as a module, choose M here: the module will be
> +	  called cyapa.
> +
>  config MOUSE_INPORT
>  	tristate "InPort/MS/ATIXL busmouse"
>  	depends on ISA
> diff --git a/drivers/input/mouse/Makefile b/drivers/input/mouse/Makefile
> index 46ba755..10b4773 100644
> --- a/drivers/input/mouse/Makefile
> +++ b/drivers/input/mouse/Makefile
> @@ -8,6 +8,7 @@ obj-$(CONFIG_MOUSE_AMIGA)		+= amimouse.o
>  obj-$(CONFIG_MOUSE_APPLETOUCH)		+= appletouch.o
>  obj-$(CONFIG_MOUSE_ATARI)		+= atarimouse.o
>  obj-$(CONFIG_MOUSE_BCM5974)		+= bcm5974.o
> +obj-$(CONFIG_MOUSE_CYAPA)		+= cyapa.o
>  obj-$(CONFIG_MOUSE_GPIO)		+= gpio_mouse.o
>  obj-$(CONFIG_MOUSE_INPORT)		+= inport.o
>  obj-$(CONFIG_MOUSE_LOGIBM)		+= logibm.o
> diff --git a/drivers/input/mouse/cyapa.c b/drivers/input/mouse/cyapa.c
> new file mode 100644
> index 0000000..8af0970
> --- /dev/null
> +++ b/drivers/input/mouse/cyapa.c
> @@ -0,0 +1,1493 @@
> +/*
> + * Cypress APA trackpad with I2C interface
> + *
> + * Author: Dudley Du <dudl@xxxxxxxxxxx>
> + * Further cleanup and restructuring by:
> + *   Daniel Kurtz <djkurtz@xxxxxxxxxxxx>
> + *   Benson Leung <bleung@xxxxxxxxxxxx>
> + *
> + * Copyright (C) 2011-2012 Cypress Semiconductor, Inc.
> + * Copyright (C) 2011-2012 Google, Inc.
> + *
> + * This file is subject to the terms and conditions of the GNU General Public
> + * License.  See the file COPYING in the main directory of this archive for
> + * more details.
> + */
> +
> +
> +#include <linux/delay.h>
> +#include <linux/firmware.h>
> +#include <linux/gpio.h>
> +#include <linux/i2c.h>
> +#include <linux/input.h>
> +#include <linux/input/mt.h>
> +#include <linux/interrupt.h>
> +#include <linux/irq.h>
> +#include <linux/module.h>
> +#include <linux/mutex.h>
> +#include <linux/semaphore.h>
> +#include <linux/slab.h>
> +#include <linux/uaccess.h>
> +
> +/* APA trackpad firmware generation */
> +enum cyapa_gen {
> +	CYAPA_GEN1 = 0x01,  /* only one finger supported. */
> +	CYAPA_GEN2 = 0x02,  /* max five fingers supported. */
> +	CYAPA_GEN3 = 0x03,  /* support MT-protocol B with tracking ID. */
> +};

If the firmware reports a value not in this list, the enum benefit of
a closed set is lost. Please define the values actually used instead.

> +
> +#define CYAPA_NAME   "Cypress APA Trackpad (cyapa)"
> +
> +/* commands for read/write registers of Cypress trackpad */
> +#define CYAPA_CMD_SOFT_RESET       0x00
> +#define CYAPA_CMD_POWER_MODE       0x01
> +#define CYAPA_CMD_DEV_STATUS       0x02
> +#define CYAPA_CMD_GROUP_DATA       0x03
> +#define CYAPA_CMD_GROUP_CTRL       0x04
> +#define CYAPA_CMD_GROUP_CMD        0x05
> +#define CYAPA_CMD_GROUP_QUERY      0x06
> +#define CYAPA_CMD_BL_STATUS        0x07
> +#define CYAPA_CMD_BL_HEAD          0x08
> +#define CYAPA_CMD_BL_CMD           0x09
> +#define CYAPA_CMD_BL_DATA          0x0a
> +#define CYAPA_CMD_BL_ALL           0x0b
> +#define CYAPA_CMD_BLK_PRODUCT_ID   0x0c
> +#define CYAPA_CMD_BLK_HEAD         0x0d
> +
> +/* report data start reg offset address. */
> +#define DATA_REG_START_OFFSET  0x0000
> +
> +#define BL_HEAD_OFFSET 0x00
> +#define BL_DATA_OFFSET 0x10
> +
> +/*
> + * Operational Device Status Register
> + *
> + * bit 7: Valid interrupt source
> + * bit 6 - 4: Reserved
> + * bit 3 - 2: Power status
> + * bit 1 - 0: Device status
> + */
> +#define REG_OP_STATUS     0x00
> +#define OP_STATUS_SRC     0x80
> +#define OP_STATUS_POWER   0x0c
> +#define OP_STATUS_DEV     0x03
> +#define OP_STATUS_MASK (OP_STATUS_SRC | OP_STATUS_POWER | OP_STATUS_DEV)
> +
> +/*
> + * Operational Finger Count/Button Flags Register
> + *
> + * bit 7 - 4: Number of touched finger
> + * bit 3: Valid data
> + * bit 2: Middle Physical Button
> + * bit 1: Right Physical Button
> + * bit 0: Left physical Button
> + */
> +#define REG_OP_DATA1       0x01
> +#define OP_DATA_VALID      0x08
> +#define OP_DATA_MIDDLE_BTN 0x04
> +#define OP_DATA_RIGHT_BTN  0x02
> +#define OP_DATA_LEFT_BTN   0x01
> +#define OP_DATA_BTN_MASK (OP_DATA_MIDDLE_BTN | OP_DATA_RIGHT_BTN | \
> +			  OP_DATA_LEFT_BTN)
> +
> +/*
> + * Bootloader Status Register
> + *
> + * bit 7: Busy
> + * bit 6 - 5: Reserved
> + * bit 4: Bootloader running
> + * bit 3 - 1: Reserved
> + * bit 0: Checksum valid
> + */
> +#define REG_BL_STATUS        0x01
> +#define BL_STATUS_BUSY       0x80
> +#define BL_STATUS_RUNNING    0x10
> +#define BL_STATUS_DATA_VALID 0x08
> +#define BL_STATUS_CSUM_VALID 0x01
> +
> +/*
> + * Bootloader Error Register
> + *
> + * bit 7: Invalid
> + * bit 6: Invalid security key
> + * bit 5: Bootloading
> + * bit 4: Command checksum
> + * bit 3: Flash protection error
> + * bit 2: Flash checksum error
> + * bit 1 - 0: Reserved
> + */
> +#define REG_BL_ERROR         0x02
> +#define BL_ERROR_INVALID     0x80
> +#define BL_ERROR_INVALID_KEY 0x40
> +#define BL_ERROR_BOOTLOADING 0x20
> +#define BL_ERROR_CMD_CSUM    0x10
> +#define BL_ERROR_FLASH_PROT  0x08
> +#define BL_ERROR_FLASH_CSUM  0x04
> +
> +#define REG_BL_KEY1 0x0d
> +#define REG_BL_KEY2 0x0e
> +#define REG_BL_KEY3 0x0f
> +#define BL_KEY1 0xc0
> +#define BL_KEY2 0xc1
> +#define BL_KEY3 0xc2
> +
> +#define BL_STATUS_SIZE  3  /* length of bootloader status registers */
> +#define BLK_HEAD_BYTES 32
> +
> +/* Macro for register map group offset. */
> +#define CYAPA_REG_MAP_SIZE  256
> +
> +#define PRODUCT_ID_SIZE  16
> +#define QUERY_DATA_SIZE  27
> +#define REG_PROTOCOL_GEN_QUERY_OFFSET  20
> +
> +#define REG_OFFSET_DATA_BASE     0x0000
> +#define REG_OFFSET_CONTROL_BASE  0x0000
> +#define REG_OFFSET_COMMAND_BASE  0x0028
> +#define REG_OFFSET_QUERY_BASE    0x002a
> +
> +#define CYAPA_OFFSET_SOFT_RESET  REG_OFFSET_COMMAND_BASE
> +
> +#define REG_OFFSET_POWER_MODE (REG_OFFSET_COMMAND_BASE + 1)
> +#define SET_POWER_MODE_DELAY   10000  /* unit: us */
> +#define SET_POWER_MODE_TRIES   5
> +
> +#define PWR_MODE_MASK   0xfc
> +#define PWR_MODE_FULL_ACTIVE (0x3f << 2)
> +#define PWR_MODE_IDLE        (0x05 << 2) /* default sleep time is 50 ms. */
> +#define PWR_MODE_BTN_ONLY    (0x01 << 2)
> +#define PWR_MODE_OFF         (0x00 << 2)
> +
> +#define BTN_ONLY_MODE_NAME   "buttononly"
> +
> +#define PWR_STATUS_MASK      0x0c
> +#define PWR_STATUS_ACTIVE    (0x03 << 2)
> +#define PWR_STATUS_IDLE      (0x02 << 2)
> +#define PWR_STATUS_BTN_ONLY  (0x01 << 2)
> +#define PWR_STATUS_OFF       (0x00 << 2)

It seems some of the values defined above are not used in the driver.

> +
> +/*
> + * CYAPA trackpad device states.
> + * Used in register 0x00, bit1-0, DeviceStatus field.
> + * After trackpad boots, and can report data, it sets this value.
> + * Other values indicate device is in an abnormal state and must be reset.
> + */
> +#define CYAPA_DEV_NORMAL  0x03
> +
> +enum cyapa_state {
> +	CYAPA_STATE_OP,
> +	CYAPA_STATE_BL_IDLE,
> +	CYAPA_STATE_BL_ACTIVE,
> +	CYAPA_STATE_BL_BUSY,
> +	CYAPA_STATE_NO_DEVICE,
> +};
> +
> +
> +struct cyapa_touch {
> +	/*
> +	 * high bits or x/y position value
> +	 * bit 7 - 4: high 4 bits of x position value
> +	 * bit 3 - 0: high 4 bits of y position value
> +	 */
> +	u8 xy;
> +	u8 x;  /* low 8 bits of x position value. */
> +	u8 y;  /* low 8 bits of y position value. */

Other recent and similar drivers use x_hi and x_lo here.

> +	u8 pressure;
> +	/* id range is 1 - 15.  It is incremented with every new touch. */
> +	u8 id;
> +} __packed;
> +
> +/* The touch.id is used as the MT slot id, thus max MT slot is 15 */
> +#define CYAPA_MAX_MT_SLOTS  15
> +
> +/* CYAPA reports up to 5 touches per packet. */
> +#define CYAPA_MAX_TOUCHES  5

Since this is a transport protocol detail, perhaps the name should be
less generic. Alternatively, why not just use [5] below.

> +
> +struct cyapa_reg_data {
> +	/*
> +	 * bit 0 - 1: device status
> +	 * bit 3 - 2: power mode
> +	 * bit 6 - 4: reserved
> +	 * bit 7: interrupt valid bit
> +	 */
> +	u8 device_status;
> +	/*
> +	 * bit 7 - 4: number of fingers currently touching pad
> +	 * bit 3: valid data check bit
> +	 * bit 2: middle mechanism button state if exists
> +	 * bit 1: right mechanism button state if exists
> +	 * bit 0: left mechanism button state if exists
> +	 */
> +	u8 finger_btn;
> +	struct cyapa_touch touches[CYAPA_MAX_TOUCHES];
> +} __packed;
> +
> +/* The main device structure */
> +struct cyapa {
> +	enum cyapa_state state;
> +
> +	struct i2c_client	*client;
> +	struct input_dev	*input;
> +	char *phys;	/* device physical location */
> +	int irq;
> +	bool irq_wake;  /* irq wake is enabled */
> +
> +	/* power mode settings */
> +	u8 suspend_power_mode;
> +
> +	/* read from query data region. */
> +	char product_id[16];
> +	u8 capability[14];
> +	u8 fw_maj_ver;  /* firmware major version. */
> +	u8 fw_min_ver;  /* firmware minor version. */
> +	u8 hw_maj_ver;  /* hardware major version. */
> +	u8 hw_min_ver;  /* hardware minor version. */
> +	enum cyapa_gen gen;
> +	int max_abs_x;
> +	int max_abs_y;
> +	int physical_size_x;
> +	int physical_size_y;
> +};
> +
> +static const u8 bl_activate[] = { 0x00, 0xff, 0x38, 0x00, 0x01, 0x02, 0x03,
> +		0x04, 0x05, 0x06, 0x07 };
> +static const u8 bl_deactivate[] = { 0x00, 0xff, 0x3b, 0x00, 0x01, 0x02, 0x03,
> +		0x04, 0x05, 0x06, 0x07 };
> +static const u8 bl_exit[] = { 0x00, 0xff, 0xa5, 0x00, 0x01, 0x02, 0x03, 0x04,
> +		0x05, 0x06, 0x07 };
> +
> +struct cyapa_cmd_len {
> +	unsigned char cmd;
> +	unsigned char len;
> +};
> +
> +#define CYAPA_ADAPTER_FUNC_NONE   0
> +#define CYAPA_ADAPTER_FUNC_I2C    1
> +#define CYAPA_ADAPTER_FUNC_SMBUS  2
> +#define CYAPA_ADAPTER_FUNC_BOTH   3
> +
> +static const struct cyapa_cmd_len cyapa_i2c_cmds[] = {
> +	{CYAPA_OFFSET_SOFT_RESET, 1},
> +	{REG_OFFSET_COMMAND_BASE + 1, 1},
> +	{REG_OFFSET_DATA_BASE, 1},
> +	{REG_OFFSET_DATA_BASE, sizeof(struct cyapa_reg_data)},
> +	{REG_OFFSET_CONTROL_BASE, 0},
> +	{REG_OFFSET_COMMAND_BASE, 0},
> +	{REG_OFFSET_QUERY_BASE, QUERY_DATA_SIZE},
> +	{BL_HEAD_OFFSET, 3},
> +	{BL_HEAD_OFFSET, 16},
> +	{BL_HEAD_OFFSET, 16},
> +	{BL_DATA_OFFSET, 16},
> +	{BL_HEAD_OFFSET, 32},
> +	{REG_OFFSET_QUERY_BASE, PRODUCT_ID_SIZE},
> +	{REG_OFFSET_DATA_BASE, 32}
> +};
> +
> +#define CYAPA_FW_NAME		"cyapa.bin"
> +#define CYAPA_FW_BLOCK_SIZE	64
> +#define CYAPA_FW_HDR_START	0x0780
> +#define CYAPA_FW_HDR_BLOCK_COUNT  2
> +#define CYAPA_FW_HDR_BLOCK_START  (CYAPA_FW_HDR_START / CYAPA_FW_BLOCK_SIZE)
> +#define CYAPA_FW_HDR_SIZE	(CYAPA_FW_HDR_BLOCK_COUNT * \
> +				 CYAPA_FW_BLOCK_SIZE)
> +#define CYAPA_FW_DATA_START	0x0800
> +#define CYAPA_FW_DATA_BLOCK_COUNT  480
> +#define CYAPA_FW_DATA_BLOCK_START  (CYAPA_FW_DATA_START / CYAPA_FW_BLOCK_SIZE)
> +#define CYAPA_FW_DATA_SIZE	(CYAPA_FW_DATA_BLOCK_COUNT * \
> +				 CYAPA_FW_BLOCK_SIZE)
> +#define CYAPA_FW_SIZE		(CYAPA_FW_HDR_SIZE + CYAPA_FW_DATA_SIZE)

There have been a number of similar i2c devices popping up recently.
To, in a driver, present an interface that can convert the trackpad
into a coffee machine is just so entangled.  After all, a kernel
driver is really about conformity, not diversity.  If you must have
it, a generic firmware update scheme via i2c would make more sense.
Or the whole firmware business could simply stay in userspace.

> +#define CYAPA_CMD_LEN		16
> +
> +static void cyapa_detect(struct cyapa *cyapa);

Indicates something needs simplification.

> +
> +#define BYTE_PER_LINE  8
> +void cyapa_dump_data(struct cyapa *cyapa, size_t length, const u8 *data)
> +{
> +	struct device *dev = &cyapa->client->dev;
> +	int i;
> +	char buf[BYTE_PER_LINE * 3 + 1];
> +	char *s = buf;
> +
> +	for (i = 0; i < length; i++) {
> +		s += sprintf(s, " %02x", data[i]);
> +		if ((i + 1) == length || ((i + 1) % BYTE_PER_LINE) == 0) {
> +			dev_dbg(dev, "%s\n", buf);
> +			s = buf;
> +		}
> +	}
> +}
> +#undef BYTE_PER_LINE

Trailing data never written? Either way look like development
data. Please simplify, correct or remove altogether.

> +
> +/*
> + * cyapa_i2c_reg_read_block - read a block of data from device i2c registers
> + * @cyapa  - private data structure of driver
> + * @reg    - register at which to start reading
> + * @length - length of block to read, in bytes
> + * @values - buffer to store values read from registers
> + *
> + * Returns negative errno, else number of bytes read.
> + *
> + * Note: The trackpad register block is 256 bytes.
> + */
> +static ssize_t cyapa_i2c_reg_read_block(struct cyapa *cyapa, u8 reg, size_t len,
> +					u8 *values)
> +{
> +	struct device *dev = &cyapa->client->dev;
> +	ssize_t ret;
> +
> +	ret = i2c_smbus_read_i2c_block_data(cyapa->client, reg, len, values);
> +	dev_dbg(dev, "i2c read block reg: 0x%02x len: %zu ret: %zd\n",
> +		reg, len, ret);
> +	if (ret > 0)
> +		cyapa_dump_data(cyapa, ret, values);
> +
> +	return ret;
> +}
> +
> +/*
> + * cyapa_i2c_reg_write_block - write a block of data to device i2c registers
> + * @cyapa  - private data structure of driver
> + * @reg    - register at which to start writing
> + * @length - length of block to write, in bytes
> + * @values - buffer to write to i2c registers
> + *
> + * Returns 0 on success, else negative errno on failure.
> + *
> + * Note: The trackpad register block is 256 bytes.
> + */
> +static ssize_t cyapa_i2c_reg_write_block(struct cyapa *cyapa, u8 reg,
> +					 size_t len, const u8 *values)
> +{
> +	struct device *dev = &cyapa->client->dev;
> +	ssize_t ret;
> +
> +	ret = i2c_smbus_write_i2c_block_data(cyapa->client, reg, len, values);
> +	dev_dbg(dev, "i2c write block reg: 0x%02x len: %zu ret: %zd\n",
> +		reg, len, ret);
> +	cyapa_dump_data(cyapa, len, values);
> +
> +	return ret;
> +}
> +
> +static s32 cyapa_read_byte(struct cyapa *cyapa, u8 cmd_idx)
> +{
> +	struct device *dev = &cyapa->client->dev;
> +	int ret;
> +	u8 cmd;
> +
> +	cmd = cyapa_i2c_cmds[cmd_idx].cmd;
> +	ret = i2c_smbus_read_byte_data(cyapa->client, cmd);
> +	dev_dbg(dev, "read byte [0x%02x] = 0x%02x  ret: %d\n",
> +		cmd, ret, ret);
> +
> +	return ret;
> +}
> +
> +static s32 cyapa_write_byte(struct cyapa *cyapa, u8 cmd_idx, u8 value)
> +{
> +	struct device *dev = &cyapa->client->dev;
> +	int ret;
> +	u8 cmd;
> +
> +	cmd = cyapa_i2c_cmds[cmd_idx].cmd;
> +	ret = i2c_smbus_write_byte_data(cyapa->client, cmd, value);
> +	dev_dbg(dev, "write byte [0x%02x] = 0x%02x  ret: %d\n",
> +		cmd, value, ret);
> +
> +	return ret;
> +}
> +

Are you sure you really need all the debug statements above?

> +static ssize_t cyapa_read_block(struct cyapa *cyapa, u8 cmd_idx, u8 *values)
> +{
> +	u8 cmd;
> +	size_t len;
> +
> +	cmd = cyapa_i2c_cmds[cmd_idx].cmd;
> +	len = cyapa_i2c_cmds[cmd_idx].len;
> +	return cyapa_i2c_reg_read_block(cyapa, cmd, len, values);
> +}
> +
> +/*
> + * Query device for its current operating state.
> + *
> + * Possible states are:
> + *   OPERATION_MODE
> + *   BOOTLOADER_IDLE
> + *   BOOTLOADER_ACTIVE
> + *   BOOTLOADER_BUSY
> + *   NO_DEVICE

This seems redundant, given the enum...

> + *
> + * Returns:
> + *   0 on success, and sets cyapa->state
> + *   < 0 on error, and sets cyapa->state = CYAPA_STATE_NO_DEVICE
> + */
> +static int cyapa_get_state(struct cyapa *cyapa)
> +{
> +	struct device *dev = &cyapa->client->dev;
> +	int ret;
> +	u8 status[BL_STATUS_SIZE];
> +
> +	cyapa->state = CYAPA_STATE_NO_DEVICE;
> +
> +	/*
> +	 * Get trackpad status by reading 3 registers starting from 0.
> +	 * If the device is in the bootloader, this will be BL_HEAD.
> +	 * If the device is in operation mode, this will be the DATA regs.
> +	 *
> +	 */
> +	ret = cyapa_i2c_reg_read_block(cyapa, BL_HEAD_OFFSET, BL_STATUS_SIZE,
> +				       status);
> +	if (ret != BL_STATUS_SIZE)
> +		return (ret < 0) ? ret : -EAGAIN;
> +
> +	if ((status[REG_OP_STATUS] & OP_STATUS_DEV) == CYAPA_DEV_NORMAL) {
> +		dev_dbg(dev, "device state: operational mode\n");
> +		cyapa->state = CYAPA_STATE_OP;
> +	} else if (status[REG_BL_STATUS] & BL_STATUS_BUSY) {
> +		dev_dbg(dev, "device state: bootloader busy\n");
> +		cyapa->state = CYAPA_STATE_BL_BUSY;
> +	} else if (status[REG_BL_ERROR] & BL_ERROR_BOOTLOADING) {
> +		dev_dbg(dev, "device state: bootloader active\n");
> +		cyapa->state = CYAPA_STATE_BL_ACTIVE;
> +	} else {
> +		dev_dbg(dev, "device state: bootloader idle\n");
> +		cyapa->state = CYAPA_STATE_BL_IDLE;
> +	}
> +
> +	return 0;
> +}
> +/*
> + * Poll device for its status in a loop, waiting up to timeout for a response.
> + *
> + * When the device switches state, it usually takes ~300 ms.
> + * Howere, when running a new firmware image, the device must calibrate its
> + * sensors, which can take as long as 2 seconds.
> + *
> + * Note: The timeout has granularity of the polling rate, which is 300 ms.
> + *
> + * Returns:
> + *   0 when the device eventually responds with a valid non-busy state.
> + *   -ETIMEDOUT if device never responds (too many -EAGAIN)
> + *   < 0    other errors
> + */
> +static int cyapa_poll_state(struct cyapa *cyapa, unsigned int timeout)
> +{
> +	int ret;
> +	int tries = timeout / 100;
> +
> +	ret = cyapa_get_state(cyapa);
> +	while ((ret || cyapa->state >= CYAPA_STATE_BL_BUSY) && tries--) {
> +		msleep(100);
> +		ret = cyapa_get_state(cyapa);
> +	}
> +	return (ret == -EAGAIN || ret == -ETIMEDOUT) ? -ETIMEDOUT : ret;
> +}
> +
> +/*
> + * Enter bootloader by soft resetting the device.
> + *
> + * If device is already in the bootloader, the function just returns.
> + * Otherwise, reset the device; after reset, device enters bootloader idle
> + * state immediately.
> + *
> + * Also, if device was unregister device from input core.  Device will
> + * re-register after it is detected following resumption of operational mode.
> + *
> + * Returns:
> + *   0 on success
> + *   -EAGAIN  device was reset, but is not now in bootloader idle state
> + *   < 0 if the device never responds within the timeout
> + */
> +static int cyapa_bl_enter(struct cyapa *cyapa)
> +{
> +	int ret;
> +
> +	if (cyapa->input) {
> +		disable_irq(cyapa->irq);
> +		input_unregister_device(cyapa->input);
> +		cyapa->input = NULL;
> +	}
> +
> +	if (cyapa->state != CYAPA_STATE_OP)
> +		return 0;
> +
> +	cyapa->state = CYAPA_STATE_NO_DEVICE;
> +	ret = cyapa_write_byte(cyapa, CYAPA_CMD_SOFT_RESET, 0x01);
> +	if (ret < 0)
> +		return -EIO;
> +
> +	usleep_range(25000, 50000);
> +	ret = cyapa_get_state(cyapa);
> +	if (ret < 0)
> +		return ret;
> +	if (cyapa->state != CYAPA_STATE_BL_IDLE)
> +		return -EAGAIN;
> +
> +	return 0;
> +}
> +
> +static int cyapa_bl_activate(struct cyapa *cyapa)
> +{
> +	int ret;
> +
> +	ret = cyapa_i2c_reg_write_block(cyapa, 0, sizeof(bl_activate),
> +					bl_activate);
> +	if (ret < 0)
> +		return ret;
> +
> +	/* Wait for bootloader to activate; takes between 2 and 12 seconds */
> +	msleep(2000);
> +	ret = cyapa_poll_state(cyapa, 10000);
> +	if (ret < 0)
> +		return ret;
> +	if (cyapa->state != CYAPA_STATE_BL_ACTIVE)
> +		return -EAGAIN;
> +
> +	return 0;
> +}

Hopefully we can simply remove the two functions above.

> +
> +static int cyapa_bl_deactivate(struct cyapa *cyapa)
> +{
> +	int ret;
> +
> +	ret = cyapa_i2c_reg_write_block(cyapa, 0, sizeof(bl_deactivate),
> +					bl_deactivate);
> +	if (ret < 0)
> +		return ret;
> +
> +	/* wait for bootloader to switch to idle state; should take < 100ms */
> +	msleep(100);
> +	ret = cyapa_poll_state(cyapa, 500);
> +	if (ret < 0)
> +		return ret;
> +	if (cyapa->state != CYAPA_STATE_BL_IDLE)
> +		return -EAGAIN;
> +	return 0;
> +}
> +
> +/*
> + * Exit bootloader
> + *
> + * Send bl_exit command, then wait 300 ms to let device transition to
> + * operational mode.  If this is the first time the device's firmware is
> + * running, it can take up to 2 seconds to calibrate its sensors.  So, poll
> + * the device's new state for up to 2 seconds.
> + *
> + * Returns:
> + *   -EIO    failure while reading from device
> + *   -EAGAIN device is stuck in bootloader, b/c it has invalid firmware
> + *   0       device is supported and in operational mode
> + */
> +static int cyapa_bl_exit(struct cyapa *cyapa)
> +{
> +	int ret;
> +
> +	ret = cyapa_i2c_reg_write_block(cyapa, 0, sizeof(bl_exit), bl_exit);
> +	if (ret < 0)
> +		return ret;
> +
> +	/*
> +	 * Wait for bootloader to exit, and operation mode to start.
> +	 * Normally, this takes at least 50 ms.
> +	 */
> +	usleep_range(50000, 100000);
> +	/*
> +	 * In addition, when a device boots for the first time after being
> +	 * updated to new firmware, it must first calibrate its sensors, which
> +	 * can take up to an additional 2 seconds.
> +	 */
> +	ret = cyapa_poll_state(cyapa, 2000);
> +	if (ret < 0)
> +		return ret;
> +	if (cyapa->state != CYAPA_STATE_OP)
> +		return -EAGAIN;
> +
> +	return 0;
> +}
> +
> +/*
> + * Set device power mode
> + *
> + * Write to the field to configure power state. Power states include :
> + *   Full : Max scans and report rate.
> + *   Idle : Report rate set by user specified time.
> + *   ButtonOnly : No scans for fingers. When the button is triggered,
> + *     a slave interrupt is asserted to notify host to wake up.
> + *   Off : Only awake for i2c commands from host. No function for button
> + *     or touch sensors.
> + *
> + * The power_mode command should conform to the following :
> + *   Full : 0x3f
> + *   Idle : Configurable from 20 to 1000ms. See note below for
> + *     cyapa_sleep_time_to_pwr_cmd and cyapa_pwr_cmd_to_sleep_time
> + *   ButtonOnly : 0x01
> + *   Off : 0x00
> + *
> + * Device power mode can only be set when device is in operational mode.
> + */
> +static int cyapa_set_power_mode(struct cyapa *cyapa, u8 power_mode)
> +{
> +	struct device *dev = &cyapa->client->dev;
> +	int ret;
> +	u8 power;
> +	int tries = SET_POWER_MODE_TRIES;
> +
> +	if (cyapa->state != CYAPA_STATE_OP)
> +		return 0;
> +
> +	while (true) {
> +		ret = cyapa_read_byte(cyapa, CYAPA_CMD_POWER_MODE);
> +		if (ret >= 0 || --tries < 1)
> +			break;
> +		dev_dbg(dev, "set power mode read retry. tries left = %d\n",
> +			tries);
> +		usleep_range(SET_POWER_MODE_DELAY, 2 * SET_POWER_MODE_DELAY);
> +	}
> +	if (ret < 0) {
> +		dev_err(dev, "failed to read power mode %d\n", ret);
> +		return ret;
> +	}
> +
> +	power = ret;
> +	power &= ~PWR_MODE_MASK;
> +	power |= power_mode & PWR_MODE_MASK;
> +	while (true) {
> +		ret = cyapa_write_byte(cyapa, CYAPA_CMD_POWER_MODE, power);
> +		if (!ret || --tries < 1)
> +			break;
> +		dev_dbg(dev, "set power mode write retry. tries left = %d\n",
> +			tries);
> +		usleep_range(SET_POWER_MODE_DELAY, 2 * SET_POWER_MODE_DELAY);
> +	}
> +	if (ret < 0)
> +		dev_err(dev, "failed to set power_mode 0x%02x err = %d\n",
> +			power_mode, ret);
> +	return ret;
> +}
> +
> +static int cyapa_get_query_data(struct cyapa *cyapa)
> +{
> +	u8 query_data[QUERY_DATA_SIZE];
> +	int ret;
> +
> +	if (cyapa->state != CYAPA_STATE_OP)
> +		return -EBUSY;
> +
> +	ret = cyapa_read_block(cyapa, CYAPA_CMD_GROUP_QUERY, query_data);
> +	if (ret < 0)
> +		return ret;
> +	if (ret != QUERY_DATA_SIZE)
> +		return -EIO;
> +
> +	memcpy(&cyapa->product_id[0], &query_data[0], 5);
> +	cyapa->product_id[5] = '-';
> +	memcpy(&cyapa->product_id[6], &query_data[5], 6);
> +	cyapa->product_id[12] = '-';
> +	memcpy(&cyapa->product_id[13], &query_data[11], 2);
> +	cyapa->product_id[15] = '\0';
> +
> +	cyapa->fw_maj_ver = query_data[15];
> +	cyapa->fw_min_ver = query_data[16];
> +	cyapa->hw_maj_ver = query_data[17];
> +	cyapa->hw_min_ver = query_data[18];
> +
> +	cyapa->gen = query_data[20] & 0x0f;
> +
> +	cyapa->max_abs_x = ((query_data[21] & 0xf0) << 4) | query_data[22];
> +	cyapa->max_abs_y = ((query_data[21] & 0x0f) << 8) | query_data[23];
> +
> +	cyapa->physical_size_x =
> +		((query_data[24] & 0xf0) << 4) | query_data[25];
> +	cyapa->physical_size_y =
> +		((query_data[24] & 0x0f) << 8) | query_data[26];
> +
> +	return 0;
> +}
> +
> +/*
> + * Check if device is operational.
> + *
> + * An operational device is responding, has exited bootloader, and has
> + * firmware supported by this driver.
> + *
> + * Returns:
> + *   -EBUSY  no device or in bootloader
> + *   -EIO    failure while reading from device
> + *   -EAGAIN device is still in bootloader
> + *           if ->state = CYAPA_STATE_BL_IDLE, device has invalid firmware
> + *   -EINVAL device is in operational mode, but not supported by this driver
> + *   0       device is supported
> + */
> +static int cyapa_check_is_operational(struct cyapa *cyapa)
> +{
> +	struct device *dev = &cyapa->client->dev;
> +	const char unique_str[] = "CYTRA";
> +	int ret;
> +
> +	ret = cyapa_poll_state(cyapa, 2000);
> +	if (ret < 0)
> +		return ret;
> +	switch (cyapa->state) {
> +	case CYAPA_STATE_BL_ACTIVE:
> +		ret = cyapa_bl_deactivate(cyapa);
> +		if (ret)
> +			return ret;
> +
> +	/* Fallthrough state */
> +	case CYAPA_STATE_BL_IDLE:
> +		ret = cyapa_bl_exit(cyapa);
> +		if (ret)
> +			return ret;
> +
> +	/* Fallthrough state */
> +	case CYAPA_STATE_OP:
> +		ret = cyapa_get_query_data(cyapa);
> +		if (ret < 0)
> +			return ret;
> +
> +		/* only support firmware protocol gen3 */
> +		if (cyapa->gen != CYAPA_GEN3) {
> +			dev_err(dev, "unsupported protocol version (%d)",
> +				cyapa->gen);
> +			return -EINVAL;
> +		}
> +
> +		/* only support product ID starting with CYTRA */
> +		if (memcmp(cyapa->product_id, unique_str,
> +			   sizeof(unique_str) - 1)) {

The zero not identical?

> +			dev_err(dev, "unsupported product ID (%s)\n",
> +				cyapa->product_id);
> +			return -EINVAL;
> +		}
> +		return 0;
> +
> +	default:
> +		return -EIO;
> +	}
> +	return 0;
> +}
> +
> +static u16 cyapa_csum(const u8 *buf, size_t count)
> +{
> +	int i;
> +	u16 csum = 0;
> +
> +	for (i = 0; i < count; i++)
> +		csum += buf[i];
> +
> +	return csum;
> +}
> +
> +/*
> + * Write a |len| byte long buffer |buf| to the device, by chopping it up into a
> + * sequence of smaller |CYAPA_CMD_LEN|-length write commands.
> + *
> + * The data bytes for a write command are prepended with the 1-byte offset
> + * of the data relative to the start of |buf|.
> + */
> +static int cyapa_write_buffer(struct cyapa *cyapa, const u8 *buf, size_t len)
> +{
> +	int ret;
> +	size_t i;
> +	unsigned char cmd[CYAPA_CMD_LEN + 1];
> +	size_t cmd_len;
> +
> +	for (i = 0; i < len; i += CYAPA_CMD_LEN) {
> +		const u8 *payload = &buf[i];
> +		cmd_len = (len - i >= CYAPA_CMD_LEN) ? CYAPA_CMD_LEN : len - i;
> +		cmd[0] = i;
> +		memcpy(&cmd[1], payload, cmd_len);
> +
> +		ret = cyapa_i2c_reg_write_block(cyapa, 0, cmd_len + 1, cmd);
> +		if (ret < 0)
> +			return ret;
> +	}
> +	return 0;
> +}
> +
> +/*
> + * A firmware block write command writes 64 bytes of data to a single flash
> + * page in the device.  The 78-byte block write command has the format:
> + *   <0xff> <CMD> <Key> <Start> <Data> <Data-Checksum> <CMD Checksum>
> + *
> + *  <0xff>  - every command starts with 0xff
> + *  <CMD>   - the write command value is 0x39
> + *  <Key>   - write commands include an 8-byte key: { 00 01 02 03 04 05 06 07 }
> + *  <Block> - Memory Block number (address / 64) (16-bit, big-endian)
> + *  <Data>  - 64 bytes of firmware image data
> + *  <Data Checksum> - sum of 64 <Data> bytes, modulo 0xff
> + *  <CMD Checksum> - sum of 77 bytes, from 0xff to <Data Checksum>
> + *
> + * Each write command is split into 5 i2c write transactions of up to 16 bytes.
> + * Each transaction starts with an i2c register offset: (00, 10, 20, 30, 40).
> + */
> +static int cyapa_write_fw_block(struct cyapa *cyapa, u16 block, const u8 *data)
> +{
> +	int ret;
> +	u8 cmd[78];
> +	u8 status[BL_STATUS_SIZE];
> +	int tries = 3;
> +
> +	/* set write command and security key bytes. */
> +	cmd[0] = 0xff;
> +	cmd[1] = 0x39;
> +	cmd[2] = 0x00;
> +	cmd[3] = 0x01;
> +	cmd[4] = 0x02;
> +	cmd[5] = 0x03;
> +	cmd[6] = 0x04;
> +	cmd[7] = 0x05;
> +	cmd[8] = 0x06;
> +	cmd[9] = 0x07;
> +	cmd[10] = block >> 8;
> +	cmd[11] = block;
> +	memcpy(&cmd[12], data, CYAPA_FW_BLOCK_SIZE);
> +	cmd[76] = cyapa_csum(data, CYAPA_FW_BLOCK_SIZE);
> +	cmd[77] = cyapa_csum(cmd, sizeof(cmd) - 1);
> +
> +	ret = cyapa_write_buffer(cyapa, cmd, sizeof(cmd));
> +	if (ret)
> +		return ret;
> +
> +	/* wait for write to finish */
> +	do {
> +		usleep_range(10000, 20000);
> +
> +		/* check block write command result status. */
> +		ret = cyapa_i2c_reg_read_block(cyapa, BL_HEAD_OFFSET,
> +					       BL_STATUS_SIZE, status);
> +		if (ret != BL_STATUS_SIZE)
> +			return (ret < 0) ? ret : -EIO;
> +		ret = (status[1] == 0x10 && status[2] == 0x20) ? 0 : -EIO;
> +	} while (--tries && ret);
> +
> +	return ret;
> +}

Hopefully for some other place, then.

> +
> +/*
> + * Verify the integrity of a CYAPA firmware image file.
> + *
> + * The firmware image file is 30848 bytes, composed of 482 64-byte blocks.
> + *
> + * The first 2 blocks are the firmware header.
> + * The next 480 blocks are the firmware image.
> + *
> + * The first two bytes of the header hold the header checksum, computed by
> + * summing the other 126 bytes of the header.
> + * The last two bytes of the header hold the firmware image checksum, computed
> + * by summing the 30720 bytes of the image modulo 0xffff.
> + *
> + * Both checksums are stored little-endian.
> + */
> +static int cyapa_check_fw(struct cyapa *cyapa, const struct firmware *fw)
> +{
> +	struct device *dev = &cyapa->client->dev;
> +	u16 csum;
> +	u16 csum_expected;
> +
> +	/* Firmware must match exact 30848 bytes = 482 64-byte blocks. */
> +	if (fw->size != CYAPA_FW_SIZE) {
> +		dev_err(dev, "invalid firmware size = %zu, expected %u.\n",
> +			fw->size, CYAPA_FW_SIZE);
> +		return -EINVAL;
> +	}
> +
> +	/* Verify header block */
> +	csum_expected = (fw->data[0] << 8) | fw->data[1];
> +	csum = cyapa_csum(&fw->data[2], CYAPA_FW_HDR_SIZE - 2);
> +	if (csum != csum_expected) {
> +		dev_err(dev, "invalid firmware header checksum = %04x,", csum);
> +		dev_err(dev, " expected: %04x\n", csum_expected);
> +		return -EINVAL;
> +	}
> +
> +	/* Verify firmware image */
> +	csum_expected = (fw->data[CYAPA_FW_HDR_SIZE - 2] << 8) |
> +			 fw->data[CYAPA_FW_HDR_SIZE - 1];
> +	csum = cyapa_csum(&fw->data[CYAPA_FW_HDR_SIZE], CYAPA_FW_DATA_SIZE);
> +	if (csum != csum_expected) {
> +		dev_err(dev, "invalid firmware checksum = %04x,", csum);
> +		dev_err(dev, " expected: %04x\n", csum_expected);
> +		return -EINVAL;
> +	}
> +	return 0;
> +}

Ditto

> +
> +static int cyapa_firmware(struct cyapa *cyapa)
> +{
> +	struct device *dev = &cyapa->client->dev;
> +	int ret;
> +	const struct firmware *fw;
> +	const char *fw_name = CYAPA_FW_NAME;
> +	int i;
> +
> +	ret = request_firmware(&fw, CYAPA_FW_NAME, dev);
> +	if (ret) {
> +		dev_err(dev, "Could not load firmware from %s, %d\n",
> +			  fw_name, ret);
> +		return ret;
> +	}
> +
> +	ret = cyapa_check_fw(cyapa, fw);
> +	if (ret) {
> +		dev_err(dev, "Invalid CYAPA firmware image: %s\n", fw_name);
> +		goto done;
> +	}
> +
> +	ret = cyapa_bl_enter(cyapa);
> +	if (ret)
> +		goto err_detect;
> +
> +	ret = cyapa_bl_activate(cyapa);
> +	if (ret)
> +		goto err_detect;
> +
> +	/* First write data, starting at byte 128  of fw->data */
> +	for (i = 0; i < CYAPA_FW_DATA_BLOCK_COUNT; i++) {
> +		size_t block = CYAPA_FW_DATA_BLOCK_START + i;
> +		size_t addr = (i + CYAPA_FW_HDR_BLOCK_COUNT) *
> +				CYAPA_FW_BLOCK_SIZE;
> +		const u8 *data = &fw->data[addr];
> +		ret = cyapa_write_fw_block(cyapa, block, data);
> +		if (ret)
> +			goto err_detect;
> +	}
> +
> +	/* Then write checksum */
> +	for (i = 0; i < CYAPA_FW_HDR_BLOCK_COUNT; i++) {
> +		size_t block = CYAPA_FW_HDR_BLOCK_START + i;
> +		size_t addr = i * CYAPA_FW_BLOCK_SIZE;
> +		const u8 *data = &fw->data[addr];
> +		ret = cyapa_write_fw_block(cyapa, block, data);
> +		if (ret)
> +			goto err_detect;
> +	}
> +
> +err_detect:
> +	cyapa_detect(cyapa);
> +
> +done:
> +	release_firmware(fw);
> +	return ret;
> +}

Ditto

> +
> +/*
> + *******************************************************************
> + *	Sysfs Interface.
> + *******************************************************************
> + */
> +static ssize_t cyapa_show_fm_ver(struct device *dev,
> +				 struct device_attribute *attr, char *buf)
> +{
> +	struct cyapa *cyapa = dev_get_drvdata(dev);
> +	return scnprintf(buf, PAGE_SIZE, "%d.%d\n", cyapa->fw_maj_ver,
> +			 cyapa->fw_min_ver);
> +}
> +
> +static ssize_t cyapa_show_hw_ver(struct device *dev,
> +				 struct device_attribute *attr, char *buf)
> +{
> +	struct cyapa *cyapa = dev_get_drvdata(dev);
> +	return scnprintf(buf, PAGE_SIZE, "%d.%d\n", cyapa->hw_maj_ver,
> +			 cyapa->hw_min_ver);
> +}
> +
> +static ssize_t cyapa_show_product_id(struct device *dev,
> +				     struct device_attribute *attr, char *buf)
> +{
> +	struct cyapa *cyapa = dev_get_drvdata(dev);
> +	return scnprintf(buf, PAGE_SIZE, "%s\n", cyapa->product_id);
> +}
> +
> +static ssize_t cyapa_show_protocol_version(struct device *dev,
> +					   struct device_attribute *attr,
> +					   char *buf)
> +{
> +	struct cyapa *cyapa = dev_get_drvdata(dev);
> +	return scnprintf(buf, PAGE_SIZE, "%d\n", cyapa->gen);
> +}
> +
> +static ssize_t cyapa_update_fw_store(struct device *dev,
> +				     struct device_attribute *attr,
> +				     const char *buf, size_t count)
> +{
> +	struct cyapa *cyapa = dev_get_drvdata(dev);
> +	int ret;
> +
> +	ret = cyapa_firmware(cyapa);
> +	if (ret)
> +		dev_err(dev, "firmware update failed, %d\n", ret);
> +	else
> +		dev_dbg(dev, "firmware update succeeded\n");
> +
> +	return ret ? ret : count;
> +}

Rather not, please.

> +
> +/*
> + * cyapa_sleep_time_to_pwr_cmd and cyapa_pwr_cmd_to_sleep_time
> + *
> + * These are helper functions that convert to and from integer idle
> + * times and register settings to write to the PowerMode register.
> + * The trackpad supports between 20ms to 1000ms scan intervals.
> + * The time will be increased in increments of 10ms from 20ms to 100ms.
> + * From 100ms to 1000ms, time will be increased in increments of 20ms.
> + *
> + * When Idle_Time < 100, the format to convert Idle_Time to Idle_Command is:
> + *   Idle_Command = Idle Time / 10;
> + * When Idle_Time >= 100, the format to convert Idle_Time to Idle_Command is:
> + *   Idle_Command = Idle Time / 20 + 5;
> + */
> +static u8 cyapa_sleep_time_to_pwr_cmd(u16 sleep_time)
> +{
> +	if (sleep_time < 20)
> +		sleep_time = 20;     /* minimal sleep time. */
> +	else if (sleep_time > 1000)
> +		sleep_time = 1000;   /* maximal sleep time. */
> +
> +	if (sleep_time < 100)
> +		return ((sleep_time / 10) << 2) & PWR_MODE_MASK;
> +	else
> +		return ((sleep_time / 20 + 5) << 2) & PWR_MODE_MASK;
> +}
> +
> +static u16 cyapa_pwr_cmd_to_sleep_time(u8 pwr_mode)
> +{
> +	u8 encoded_time = pwr_mode >> 2;
> +	return (encoded_time < 10) ? encoded_time * 10
> +				   : (encoded_time - 5) * 20;
> +}
> +
> +#ifdef CONFIG_PM_SLEEP
> +static ssize_t cyapa_show_suspend_scanrate(struct device *dev,
> +					   struct device_attribute *attr,
> +					   char *buf)
> +{
> +	struct cyapa *cyapa = dev_get_drvdata(dev);
> +	int len;
> +	u8 pwr_cmd = cyapa->suspend_power_mode;
> +
> +	if (pwr_cmd == PWR_MODE_BTN_ONLY)
> +		len = scnprintf(buf, PAGE_SIZE, "%s\n", BTN_ONLY_MODE_NAME);
> +	else
> +		len = scnprintf(buf, PAGE_SIZE, "%u\n",
> +				cyapa_pwr_cmd_to_sleep_time(pwr_cmd));
> +	return len;
> +}
> +
> +static ssize_t cyapa_update_suspend_scanrate(struct device *dev,
> +					     struct device_attribute *attr,
> +					     const char *buf, size_t count)
> +{
> +	struct cyapa *cyapa = dev_get_drvdata(dev);
> +	u8 pwr_cmd;
> +	u16 sleep_time;
> +
> +	if (buf == NULL || count == 0)
> +		goto invalidparam;
> +
> +	if (sysfs_streq(buf, BTN_ONLY_MODE_NAME))
> +		pwr_cmd = PWR_MODE_BTN_ONLY;
> +	else if (!kstrtou16(buf, 10, &sleep_time))
> +		pwr_cmd = cyapa_sleep_time_to_pwr_cmd(sleep_time);
> +	else
> +		goto invalidparam;
> +
> +	cyapa->suspend_power_mode = pwr_cmd;
> +	return count;
> +
> +invalidparam:
> +	dev_err(dev, "invalid suspend scanrate ms parameters\n");
> +	return -EINVAL;
> +}
> +
> +static DEVICE_ATTR(suspend_scanrate_ms, S_IRUGO|S_IWUSR,
> +		   cyapa_show_suspend_scanrate,
> +		   cyapa_update_suspend_scanrate);

Why?

> +
> +static struct attribute *cyapa_power_wakeup_entries[] = {
> +	&dev_attr_suspend_scanrate_ms.attr,
> +	NULL,
> +};
> +
> +static const struct attribute_group cyapa_power_wakeup_group = {
> +	.name = power_group_name,
> +	.attrs = cyapa_power_wakeup_entries,
> +};
> +#endif /* CONFIG_PM_SLEEP */
> +
> +static DEVICE_ATTR(firmware_version, S_IRUGO, cyapa_show_fm_ver, NULL);
> +static DEVICE_ATTR(hardware_version, S_IRUGO, cyapa_show_hw_ver, NULL);
> +static DEVICE_ATTR(product_id, S_IRUGO, cyapa_show_product_id, NULL);
> +static DEVICE_ATTR(protocol_version, S_IRUGO, cyapa_show_protocol_version,
> +		   NULL);
> +static DEVICE_ATTR(update_fw, S_IWUSR, NULL, cyapa_update_fw_store);
> +
> +static struct attribute *cyapa_sysfs_entries[] = {
> +	&dev_attr_firmware_version.attr,
> +	&dev_attr_hardware_version.attr,
> +	&dev_attr_product_id.attr,
> +	&dev_attr_protocol_version.attr,
> +	&dev_attr_update_fw.attr,
> +	NULL,
> +};
> +
> +static const struct attribute_group cyapa_sysfs_group = {
> +	.attrs = cyapa_sysfs_entries,
> +};

At this point, only some 10% of the file is about _this_ driver and
its functionality. The rest is about some _future_ or possible
functionality. It should really be the other way around.

> +
> +/*
> + **************************************************************
> + * Cypress APA trackpad with I2C interface input device driver.
> + **************************************************************
> + */
> +
> +static irqreturn_t cyapa_irq(int irq, void *dev_id)
> +{
> +	struct cyapa *cyapa = dev_id;
> +	struct device *dev = &cyapa->client->dev;
> +	struct input_dev *input = cyapa->input;
> +	struct cyapa_reg_data data;
> +	int i;
> +	int ret;
> +	int num_fingers;
> +	unsigned int mask;
> +
> +	/*
> +	 * Don't read input if input device has not been configured.
> +	 * This check check solves a race during probe() between irq_request()
> +	 * and irq_disable(), since there is no way to request an irq that is
> +	 * initially disabled.
> +	 */
> +	if (!input)
> +		return IRQ_HANDLED;

This is just confused. Why not configure the input device before
starting the interrupt?

> +
> +	if (device_may_wakeup(dev))
> +		pm_wakeup_event(dev, 0);
> +
> +	ret = cyapa_read_block(cyapa, CYAPA_CMD_GROUP_DATA, (u8 *)&data);
> +	if (ret != sizeof(data))
> +		return IRQ_HANDLED;
> +
> +	if ((data.device_status & OP_STATUS_SRC) != OP_STATUS_SRC ||
> +	    (data.device_status & OP_STATUS_DEV) != CYAPA_DEV_NORMAL ||
> +	    (data.finger_btn & OP_DATA_VALID) != OP_DATA_VALID) {
> +		return IRQ_HANDLED;
> +	}
> +
> +	mask = 0;
> +	num_fingers = (data.finger_btn >> 4) & 0x0f;
> +	for (i = 0; i < num_fingers; i++) {
> +		const struct cyapa_touch *touch = &data.touches[i];
> +		/* Note: touch->id range is 1 to 15; slots are 0 to 14. */
> +		int slot = touch->id - 1;
> +
> +		mask |= (1 << slot);
> +		input_mt_slot(input, slot);
> +		input_mt_report_slot_state(input, MT_TOOL_FINGER, true);
> +		input_report_abs(input, ABS_MT_POSITION_X,
> +				 ((touch->xy & 0xf0) << 4) | touch->x);
> +		input_report_abs(input, ABS_MT_POSITION_Y,
> +				 ((touch->xy & 0x0f) << 8) | touch->y);
> +		input_report_abs(input, ABS_MT_PRESSURE, touch->pressure);
> +	}
> +
> +	/* Invalidate all unreported slots */
> +	for (i = 0; i < CYAPA_MAX_MT_SLOTS; i++) {
> +		if (mask & (1 << i))
> +			continue;
> +		input_mt_slot(input, i);
> +		input_mt_report_slot_state(input, MT_TOOL_FINGER, false);
> +	}
> +
> +	input_mt_report_pointer_emulation(input, true);
> +	input_report_key(input, BTN_LEFT, data.finger_btn & OP_DATA_BTN_MASK);
> +	input_sync(input);
> +
> +	return IRQ_HANDLED;
> +}
> +
> +static int cyapa_create_input_dev(struct cyapa *cyapa)
> +{
> +	struct device *dev = &cyapa->client->dev;
> +	int ret;
> +	struct input_dev *input;
> +
> +	dev_info(dev,
> +		 "Cypress APA Trackpad Information:\n" \
> +		 "    Product ID:  %s\n" \
> +		 "    Protocol Generation:  %d\n" \
> +		 "    Firmware Version:  %d.%d\n" \
> +		 "    Hardware Version:  %d.%d\n" \
> +		 "    Max ABS X,Y:   %d,%d\n" \
> +		 "    Physical Size X,Y:   %d,%d\n",
> +		 cyapa->product_id,
> +		 cyapa->gen,
> +		 cyapa->fw_maj_ver, cyapa->fw_min_ver,
> +		 cyapa->hw_maj_ver, cyapa->hw_min_ver,
> +		 cyapa->max_abs_x, cyapa->max_abs_y,
> +		 cyapa->physical_size_x, cyapa->physical_size_y);

Way too chatty for the main logs.

> +
> +	input = cyapa->input = input_allocate_device();
> +	if (!input) {
> +		dev_err(dev, "allocate memory for input device failed\n");
> +		return -ENOMEM;
> +	}
> +
> +	input->name = CYAPA_NAME;
> +	input->phys = cyapa->phys;
> +	input->id.bustype = BUS_I2C;
> +	input->id.version = 1;
> +	input->id.product = 0;  /* means any product in eventcomm. */
> +	input->dev.parent = &cyapa->client->dev;
> +
> +	input_set_drvdata(input, cyapa);
> +
> +	__set_bit(EV_ABS, input->evbit);
> +
> +	/*
> +	 * set and report not-MT axes to support synaptics X Driver.
> +	 * When multi-fingers on trackpad, only the first finger touch
> +	 * will be reported as X/Y axes values.
> +	 */
> +	input_set_abs_params(input, ABS_X, 0, cyapa->max_abs_x, 0, 0);
> +	input_set_abs_params(input, ABS_Y, 0, cyapa->max_abs_y, 0, 0);
> +	input_set_abs_params(input, ABS_PRESSURE, 0, 255, 0, 0);
> +
> +	/* finger position */
> +	input_set_abs_params(input, ABS_MT_POSITION_X, 0, cyapa->max_abs_x, 0,
> +			     0);
> +	input_set_abs_params(input, ABS_MT_POSITION_Y, 0, cyapa->max_abs_y, 0,
> +			     0);
> +	input_set_abs_params(input, ABS_MT_PRESSURE, 0, 255, 0, 0);
> +	ret = input_mt_init_slots(input, CYAPA_MAX_MT_SLOTS);
> +	if (ret < 0) {
> +		dev_err(dev, "allocate memory for MT slots failed, %d\n", ret);
> +		goto err_free_device;
> +	}
> +
> +	if (cyapa->physical_size_x && cyapa->physical_size_y) {
> +		input_abs_set_res(input, ABS_X,
> +			cyapa->max_abs_x / cyapa->physical_size_x);
> +		input_abs_set_res(input, ABS_Y,
> +			cyapa->max_abs_y / cyapa->physical_size_y);
> +		input_abs_set_res(input, ABS_MT_POSITION_X,
> +			cyapa->max_abs_x / cyapa->physical_size_x);
> +		input_abs_set_res(input, ABS_MT_POSITION_Y,
> +			cyapa->max_abs_y / cyapa->physical_size_y);
> +	}
> +
> +	__set_bit(EV_KEY, input->evbit);
> +	__set_bit(BTN_TOUCH, input->keybit);
> +	__set_bit(BTN_TOOL_FINGER, input->keybit);
> +	__set_bit(BTN_TOOL_DOUBLETAP, input->keybit);
> +	__set_bit(BTN_TOOL_TRIPLETAP, input->keybit);
> +	__set_bit(BTN_TOOL_QUADTAP, input->keybit);
> +	__set_bit(BTN_TOOL_QUINTTAP, input->keybit);
> +
> +	__set_bit(BTN_LEFT, input->keybit);
> +
> +	__set_bit(INPUT_PROP_POINTER, input->propbit);
> +	__set_bit(INPUT_PROP_BUTTONPAD, input->propbit);
> +
> +	/* Register the device in input subsystem */
> +	ret = input_register_device(input);
> +	if (ret) {
> +		dev_err(dev, "input device register failed, %d\n", ret);
> +		goto err_free_device;
> +	}
> +
> +	enable_irq(cyapa->irq);
> +	return 0;
> +
> +err_free_device:
> +	input_free_device(input);
> +	cyapa->input = NULL;
> +	return ret;
> +}
> +
> +static void cyapa_detect(struct cyapa *cyapa)
> +{
> +	struct device *dev = &cyapa->client->dev;
> +	int ret;
> +
> +	ret = cyapa_check_is_operational(cyapa);
> +	if (ret == -ETIMEDOUT) {
> +		dev_err(dev, "no device detected, %d\n", ret);
> +		return;
> +	} else if (ret) {
> +		dev_err(dev, "device detected, but not operational, %d\n", ret);
> +		return;
> +	}
> +
> +	if (!cyapa->input) {
> +		ret = cyapa_create_input_dev(cyapa);
> +		if (ret)
> +			dev_err(dev, "create input_dev instance failed, %d\n",
> +				ret);
> +
> +		/*
> +		 * On some systems, a system crash / warm boot does not reset
> +		 * the device's current power mode to FULL_ACTIVE.
> +		 * If such an event happens during suspend, after the device
> +		 * has been put in a low power mode, the device will still be
> +		 * in low power mode on a subsequent boot, since there was
> +		 * never a matching resume().
> +		 * Handle this by always forcing full power here, when a
> +		 * device is first detected to be in operational mode.
> +		 */
> +		ret = cyapa_set_power_mode(cyapa, PWR_MODE_FULL_ACTIVE);
> +		if (ret)
> +			dev_warn(dev, "set active power failed, %d\n", ret);
> +	}
> +}

This function does what that differs from probe()?

> +
> +static int __devinit cyapa_probe(struct i2c_client *client,
> +				 const struct i2c_device_id *dev_id)
> +{
> +	int ret;
> +	struct cyapa *cyapa;
> +	struct device *dev = &client->dev;
> +
> +	cyapa = kzalloc(sizeof(struct cyapa), GFP_KERNEL);
> +	if (!cyapa) {
> +		dev_err(dev, "allocate memory for cyapa failed\n");
> +		return -ENOMEM;
> +	}
> +
> +	cyapa->gen = CYAPA_GEN3;
> +	cyapa->client = client;
> +	i2c_set_clientdata(client, cyapa);
> +	cyapa->phys = kasprintf(GFP_KERNEL, "i2c-%d-%04x/input0",
> +				client->adapter->nr, client->addr);
> +	if (!cyapa->phys) {
> +		ret = -ENOMEM;
> +		goto err_mem_free;
> +	}
> +
> +
> +	cyapa->state = CYAPA_STATE_NO_DEVICE;
> +	cyapa->suspend_power_mode = PWR_MODE_IDLE;
> +
> +	/*
> +	 * Note: There is no way to request an irq that is initially disabled.
> +	 * Thus, there is a little race here, which is resolved in cyapa_irq()
> +	 * by checking that cyapa->input has been allocated, which happens
> +	 * in cyapa_detect(), before creating input events.
> +	 */
> +	cyapa->irq = client->irq;
> +	ret = request_threaded_irq(cyapa->irq,
> +				   NULL,
> +				   cyapa_irq,
> +				   IRQF_TRIGGER_FALLING,
> +				   "cyapa",
> +				   cyapa);

Excess linebreaks.

> +	if (ret) {
> +		dev_err(dev, "IRQ request failed: %d\n, ", ret);
> +		goto err_mem_free;
> +	}
> +	disable_irq(cyapa->irq);
> +
> +	if (sysfs_create_group(&client->dev.kobj, &cyapa_sysfs_group))
> +		dev_warn(dev, "error creating sysfs entries.\n");
> +
> +#ifdef CONFIG_PM_SLEEP
> +	if (device_can_wakeup(dev) &&
> +	    sysfs_merge_group(&client->dev.kobj, &cyapa_power_wakeup_group))
> +		dev_warn(dev, "error creating wakeup power entries.\n");
> +#endif /* CONFIG_PM_SLEEP */
> +
> +	cyapa_detect(cyapa);
> +
> +	return 0;
> +
> +err_mem_free:
> +	kfree(cyapa->phys);
> +	kfree(cyapa);
> +
> +	return ret;
> +}
> +
> +static int __devexit cyapa_remove(struct i2c_client *client)
> +{
> +	struct cyapa *cyapa = i2c_get_clientdata(client);
> +
> +	sysfs_remove_group(&client->dev.kobj, &cyapa_sysfs_group);
> +
> +	free_irq(cyapa->irq, cyapa);
> +
> +	if (cyapa->input)
> +		input_unregister_device(cyapa->input);
> +
> +	kfree(cyapa->phys);
> +	kfree(cyapa);
> +
> +	return 0;
> +}
> +
> +#ifdef CONFIG_PM_SLEEP
> +static int cyapa_suspend(struct device *dev)
> +{
> +	int ret;
> +	u8 power_mode;
> +	struct cyapa *cyapa = dev_get_drvdata(dev);
> +
> +	/* set trackpad device to idle mode if wakeup is allowed
> +	 * otherwise turn off. */
> +	power_mode = device_may_wakeup(dev) ? cyapa->suspend_power_mode
> +					    : PWR_MODE_OFF;
> +	ret = cyapa_set_power_mode(cyapa, power_mode);
> +	if (ret < 0)
> +		dev_err(dev, "set power mode failed, %d\n", ret);
> +
> +	if (device_may_wakeup(dev))
> +		cyapa->irq_wake = (enable_irq_wake(cyapa->irq) == 0);
> +	disable_irq(cyapa->irq);
> +
> +	return 0;
> +}
> +
> +static int cyapa_resume(struct device *dev)
> +{
> +	int ret;
> +	struct cyapa *cyapa = dev_get_drvdata(dev);
> +
> +	enable_irq(cyapa->irq);
> +	if (device_may_wakeup(dev) && cyapa->irq_wake)
> +		disable_irq_wake(cyapa->irq);
> +
> +	cyapa_detect(cyapa);
> +
> +	ret = cyapa_set_power_mode(cyapa, PWR_MODE_FULL_ACTIVE);
> +	if (ret)
> +		dev_warn(dev, "resume active power failed, %d\n", ret);
> +
> +	return 0;
> +}
> +#endif /* CONFIG_PM_SLEEP */
> +
> +static SIMPLE_DEV_PM_OPS(cyapa_pm_ops, cyapa_suspend, cyapa_resume);
> +
> +static const struct i2c_device_id cyapa_id_table[] = {
> +	{ "cyapa", 0 },
> +	{ },
> +};
> +MODULE_DEVICE_TABLE(i2c, cyapa_id_table);
> +
> +static struct i2c_driver cyapa_driver = {
> +	.driver = {
> +		.name = "cyapa",
> +		.owner = THIS_MODULE,
> +		.pm = &cyapa_pm_ops,
> +	},
> +
> +	.probe = cyapa_probe,
> +	.remove = __devexit_p(cyapa_remove),
> +	.id_table = cyapa_id_table,
> +};
> +
> +module_i2c_driver(cyapa_driver);
> +
> +MODULE_DESCRIPTION("Cypress APA I2C Trackpad Driver");
> +MODULE_AUTHOR("Dudley Du <dudl@xxxxxxxxxxx>");
> +MODULE_LICENSE("GPL");
> -- 
> 1.7.7.3
> 

All in all, it would be great to see this driver shrink to
approximately one fourth of its present size.

Thanks,
Henrik
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