Re: [PATCH 2/3] hwmon: ltc2992: Add support for GPIOs.

[Guenter Roeck <linux@roeck-us.net>]

On Thu, Oct 29, 2020 at 11:49:10AM +0200, alexandru.tachici@analog.com wrote:
> From: Alexandru Tachici <alexandru.tachici@analog.com>
> 
> LTC2992 has 4 open-drain GPIOS. This patch exports to user
> space the 4 GPIOs using the GPIO driver Linux API.
> 
> Signed-off-by: Alexandru Tachici <alexandru.tachici@analog.com>
> Reported-by: kernel test robot <lkp@intel.com>

Please fix the problem reported by 0-day and resubmit.

Thanks,
Guenter

> ---
>  drivers/hwmon/Kconfig   |   1 +
>  drivers/hwmon/ltc2992.c | 160 ++++++++++++++++++++++++++++++++++++++++
>  2 files changed, 161 insertions(+)
> 
> diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig
> index bf9e387270d6..8a8eb42fb1ec 100644
> --- a/drivers/hwmon/Kconfig
> +++ b/drivers/hwmon/Kconfig
> @@ -861,6 +861,7 @@ config SENSORS_LTC2990
>  config SENSORS_LTC2992
>  	tristate "Linear Technology LTC2992"
>  	depends on I2C
> +	depends on GPIOLIB
>  	help
>  	  If you say yes here you get support for Linear Technology LTC2992
>  	  I2C System Monitor. The LTC2992 measures current, voltage, and
> diff --git a/drivers/hwmon/ltc2992.c b/drivers/hwmon/ltc2992.c
> index 940d92b4a1d0..3fe6d34cdade 100644
> --- a/drivers/hwmon/ltc2992.c
> +++ b/drivers/hwmon/ltc2992.c
> @@ -9,6 +9,7 @@
>  #include <linux/bitops.h>
>  #include <linux/bits.h>
>  #include <linux/err.h>
> +#include <linux/gpio/driver.h>
>  #include <linux/hwmon.h>
>  #include <linux/hwmon-sysfs.h>
>  #include <linux/i2c.h>
> @@ -56,6 +57,9 @@
>  #define LTC2992_G4_MAX_THRESH		0x74
>  #define LTC2992_G4_MIN_THRESH		0x76
>  #define LTC2992_FAULT3			0x92
> +#define LTC2992_GPIO_STATUS		0x95
> +#define LTC2992_GPIO_IO_CTRL		0x96
> +#define LTC2992_GPIO_CTRL		0x97
>  
>  #define LTC2992_POWER(x)		(LTC2992_POWER1 + ((x) * 0x32))
>  #define LTC2992_POWER_MAX(x)		(LTC2992_POWER1_MAX + ((x) * 0x32))
> @@ -95,8 +99,18 @@
>  #define LTC2992_VADC_UV_LSB		25000
>  #define LTC2992_VADC_GPIO_UV_LSB	500
>  
> +#define LTC2992_GPIO_NR		4
> +#define LTC2992_GPIO1_BIT	7
> +#define LTC2992_GPIO2_BIT	6
> +#define LTC2992_GPIO3_BIT	0
> +#define LTC2992_GPIO4_BIT	6
> +#define LTC2992_GPIO_BIT(x)	(LTC2992_GPIO_NR - (x) - 1)
> +
>  struct ltc2992_state {
>  	struct i2c_client		*client;
> +	struct gpio_chip		gc;
> +	struct mutex			gpio_mutex; /* lock for gpio access */
> +	const char			*gpio_names[LTC2992_GPIO_NR];
>  	struct regmap			*regmap;
>  	u32				r_sense_uohm[2];
>  };
> @@ -109,6 +123,8 @@ struct ltc2992_gpio_regs {
>  	u8	min_thresh;
>  	u8	alarm;
>  	u8	alarm_msk;
> +	u8	ctrl;
> +	u8	ctrl_bit;
>  };
>  
>  static const struct ltc2992_gpio_regs ltc2992_gpio_addr_map[] = {
> @@ -120,6 +136,8 @@ static const struct ltc2992_gpio_regs ltc2992_gpio_addr_map[] = {
>  		.min_thresh = LTC2992_G1_MIN_THRESH,
>  		.alarm = LTC2992_FAULT1,
>  		.alarm_msk = LTC2992_GPIO1_FAULT_MSK,
> +		.ctrl = LTC2992_GPIO_IO_CTRL,
> +		.ctrl_bit = LTC2992_GPIO1_BIT,
>  	},
>  	{
>  		.data = LTC2992_G2,
> @@ -129,6 +147,8 @@ static const struct ltc2992_gpio_regs ltc2992_gpio_addr_map[] = {
>  		.min_thresh = LTC2992_G2_MIN_THRESH,
>  		.alarm = LTC2992_FAULT2,
>  		.alarm_msk = LTC2992_GPIO2_FAULT_MSK,
> +		.ctrl = LTC2992_GPIO_IO_CTRL,
> +		.ctrl_bit = LTC2992_GPIO2_BIT,
>  	},
>  	{
>  		.data = LTC2992_G3,
> @@ -138,6 +158,8 @@ static const struct ltc2992_gpio_regs ltc2992_gpio_addr_map[] = {
>  		.min_thresh = LTC2992_G3_MIN_THRESH,
>  		.alarm = LTC2992_FAULT3,
>  		.alarm_msk = LTC2992_GPIO3_FAULT_MSK,
> +		.ctrl = LTC2992_GPIO_IO_CTRL,
> +		.ctrl_bit = LTC2992_GPIO3_BIT,
>  	},
>  	{
>  		.data = LTC2992_G4,
> @@ -147,9 +169,15 @@ static const struct ltc2992_gpio_regs ltc2992_gpio_addr_map[] = {
>  		.min_thresh = LTC2992_G4_MIN_THRESH,
>  		.alarm = LTC2992_FAULT3,
>  		.alarm_msk = LTC2992_GPIO4_FAULT_MSK,
> +		.ctrl = LTC2992_GPIO_CTRL,
> +		.ctrl_bit = LTC2992_GPIO4_BIT,
>  	},
>  };
>  
> +static const char *ltc2992_gpio_names[LTC2992_GPIO_NR] = {
> +	"GPIO1", "GPIO2", "GPIO3", "GPIO4",
> +};
> +
>  static int ltc2992_read_reg(struct ltc2992_state *st, u8 addr, const u8 reg_len, u32 *val)
>  {
>  	u8 regvals[4];
> @@ -178,6 +206,134 @@ static int ltc2992_write_reg(struct ltc2992_state *st, u8 addr, const u8 reg_len
>  	return regmap_bulk_write(st->regmap, addr, regvals, reg_len);
>  }
>  
> +static int ltc2992_gpio_get(struct gpio_chip *chip, unsigned int offset)
> +{
> +	struct ltc2992_state *st = gpiochip_get_data(chip);
> +	unsigned long gpio_status;
> +	u32 reg;
> +	int ret;
> +
> +	mutex_lock(&st->gpio_mutex);
> +	ret = ltc2992_read_reg(st, LTC2992_GPIO_STATUS, 1, &reg);
> +	mutex_unlock(&st->gpio_mutex);
> +
> +	if (ret < 0)
> +		return ret;
> +
> +	gpio_status = reg;
> +
> +	return !test_bit(LTC2992_GPIO_BIT(offset), &gpio_status);
> +}
> +
> +static int ltc2992_gpio_get_multiple(struct gpio_chip *chip, unsigned long *mask,
> +				     unsigned long *bits)
> +{
> +	struct ltc2992_state *st = gpiochip_get_data(chip);
> +	unsigned long gpio_status;
> +	unsigned int gpio_nr;
> +	u32 reg;
> +	int ret;
> +
> +	mutex_lock(&st->gpio_mutex);
> +	ret = ltc2992_read_reg(st, LTC2992_GPIO_STATUS, 1, &reg);
> +	mutex_unlock(&st->gpio_mutex);
> +
> +	if (ret < 0)
> +		return ret;
> +
> +	gpio_status = reg;
> +
> +	gpio_nr = 0;
> +	for_each_set_bit_from(gpio_nr, mask, LTC2992_GPIO_NR) {
> +		if (test_bit(LTC2992_GPIO_BIT(gpio_nr), &gpio_status))
> +			set_bit(gpio_nr, bits);
> +	}
> +
> +	return 0;
> +}
> +
> +static void ltc2992_gpio_set(struct gpio_chip *chip, unsigned int offset, int value)
> +{
> +	struct ltc2992_state *st = gpiochip_get_data(chip);
> +	unsigned long gpio_ctrl;
> +	u32 reg_val;
> +	int ret;
> +
> +	mutex_lock(&st->gpio_mutex);
> +	ret = ltc2992_read_reg(st, ltc2992_gpio_addr_map[offset].ctrl, 1, &reg_val);
> +	if (ret < 0) {
> +		mutex_unlock(&st->gpio_mutex);
> +		return;
> +	}
> +
> +	gpio_ctrl = reg_val;
> +	assign_bit(ltc2992_gpio_addr_map[offset].ctrl_bit, &gpio_ctrl, value);
> +
> +	ltc2992_write_reg(st, ltc2992_gpio_addr_map[offset].ctrl, 1, gpio_ctrl);
> +	mutex_unlock(&st->gpio_mutex);
> +}
> +
> +void ltc2992_gpio_set_multiple(struct gpio_chip *chip, unsigned long *mask, unsigned long *bits)
> +{
> +	struct ltc2992_state *st = gpiochip_get_data(chip);
> +	unsigned long gpio_ctrl_io = 0;
> +	unsigned long gpio_ctrl = 0;
> +	unsigned int gpio_nr;
> +
> +	for_each_set_bit(gpio_nr, mask, LTC2992_GPIO_NR) {
> +		if (gpio_nr < 3)
> +			assign_bit(ltc2992_gpio_addr_map[gpio_nr].ctrl_bit, &gpio_ctrl_io, true);
> +
> +		if (gpio_nr == 3)
> +			assign_bit(ltc2992_gpio_addr_map[gpio_nr].ctrl_bit, &gpio_ctrl, true);
> +	}
> +
> +	mutex_lock(&st->gpio_mutex);
> +	ltc2992_write_reg(st, LTC2992_GPIO_IO_CTRL, 1, gpio_ctrl_io);
> +	ltc2992_write_reg(st, LTC2992_GPIO_CTRL, 1, gpio_ctrl);
> +	mutex_unlock(&st->gpio_mutex);
> +}
> +
> +static int ltc2992_config_gpio(struct ltc2992_state *st)
> +{
> +	const char *name = dev_name(&st->client->dev);
> +	char *gpio_name;
> +	int ret;
> +	int i;
> +
> +	ret = ltc2992_write_reg(st, LTC2992_GPIO_IO_CTRL, 1, 0);
> +	if (ret < 0)
> +		return ret;
> +
> +	mutex_init(&st->gpio_mutex);
> +
> +	for (i = 0; i < ARRAY_SIZE(st->gpio_names); i++) {
> +		gpio_name = devm_kasprintf(&st->client->dev, GFP_KERNEL, "ltc2992-%x-%s",
> +					   st->client->addr, ltc2992_gpio_names[i]);
> +		if (!gpio_name)
> +			return -ENOMEM;
> +
> +		st->gpio_names[i] = gpio_name;
> +	}
> +
> +	st->gc.label = name;
> +	st->gc.parent = &st->client->dev;
> +	st->gc.owner = THIS_MODULE;
> +	st->gc.base = -1;
> +	st->gc.names = st->gpio_names;
> +	st->gc.ngpio = ARRAY_SIZE(st->gpio_names);
> +	st->gc.get = ltc2992_gpio_get;
> +	st->gc.get_multiple = ltc2992_gpio_get_multiple;
> +	st->gc.set = ltc2992_gpio_set;
> +	st->gc.set_multiple = ltc2992_gpio_set_multiple;
> +
> +	ret = devm_gpiochip_add_data(&st->client->dev, &st->gc, st);
> +	if (ret)
> +		dev_err(&st->client->dev, "GPIO registering failed (%d)\n", ret);
> +
> +	return ret;
> +}
> +
>  static umode_t ltc2992_is_visible(const void *data, enum hwmon_sensor_types type, u32 attr,
>  				  int channel)
>  {
> @@ -701,6 +857,10 @@ static int ltc2992_i2c_probe(struct i2c_client *client, const struct i2c_device_
>  	if (ret < 0)
>  		return ret;
>  
> +	ret = ltc2992_config_gpio(st);
> +	if (ret < 0)
> +		return ret;
> +
>  	hwmon_dev = devm_hwmon_device_register_with_info(&client->dev, client->name, st,
>  							 &ltc2992_chip_info, NULL);
>