[PATCH linux dev-4.10 v2] leds: pca955x: check for I2C errors
Andrew Jeffery
andrew at aj.id.au
Tue Aug 29 15:45:06 AEST 2017
On Mon, 2017-08-28 at 08:37 +0200, Cédric Le Goater wrote:
> This should also allow probing to fail when a pca955x chip is not
> found on a I2C bus.
>
> Signed-off-by: Cédric Le Goater <clg at kaod.org>
Thanks Cédric. I've applied this to dev-4.10, fixing up the conflicts
with my series. I felt this was reasonable given we've both been
discussing the changes.
Andrew
> ---
> Changes since v1:
>
> - introduced a pca955x_set_value() routine returning an errno
> - modified pca955x_gpio_direction_{in,out}put to return an errno
>
> drivers/leds/leds-pca955x.c | 114 ++++++++++++++++++++++++++++++++------------
> 1 file changed, 83 insertions(+), 31 deletions(-)
>
> diff --git a/drivers/leds/leds-pca955x.c b/drivers/leds/leds-pca955x.c
> index 09303fd1fdc6..905729191d3e 100644
> --- a/drivers/leds/leds-pca955x.c
> +++ b/drivers/leds/leds-pca955x.c
> @@ -165,13 +165,18 @@ static inline u8 pca955x_ledsel(u8 oldval, int led_num, int state)
> * Write to frequency prescaler register, used to program the
> * period of the PWM output. period = (PSCx + 1) / 38
> */
> -static void pca955x_write_psc(struct i2c_client *client, int n, u8 val)
> +static int pca955x_write_psc(struct i2c_client *client, int n, u8 val)
> {
> > struct pca955x *pca955x = i2c_get_clientdata(client);
> > + int ret;
>
> > - i2c_smbus_write_byte_data(client,
> > + ret = i2c_smbus_write_byte_data(client,
> > pca95xx_num_input_regs(pca955x->chipdef->bits) + 2*n,
> > val);
> > + if (ret < 0)
> > + dev_err(&client->dev, "%s: reg 0x%x, val 0x%x, err %d\n",
> > + __func__, n, val, ret);
> > + return ret;
> }
>
> /*
> @@ -181,38 +186,56 @@ static void pca955x_write_psc(struct i2c_client *client, int n, u8 val)
> *
> * Duty cycle is (256 - PWMx) / 256
> */
> -static void pca955x_write_pwm(struct i2c_client *client, int n, u8 val)
> +static int pca955x_write_pwm(struct i2c_client *client, int n, u8 val)
> {
> > struct pca955x *pca955x = i2c_get_clientdata(client);
> > + int ret;
>
> > - i2c_smbus_write_byte_data(client,
> > + ret = i2c_smbus_write_byte_data(client,
> > pca95xx_num_input_regs(pca955x->chipdef->bits) + 1 + 2*n,
> > val);
> > + if (ret < 0)
> > + dev_err(&client->dev, "%s: reg 0x%x, val 0x%x, err %d\n",
> > + __func__, n, val, ret);
> > + return ret;
> }
>
> /*
> * Write to LED selector register, which determines the source that
> * drives the LED output.
> */
> -static void pca955x_write_ls(struct i2c_client *client, int n, u8 val)
> +static int pca955x_write_ls(struct i2c_client *client, int n, u8 val)
> {
> > struct pca955x *pca955x = i2c_get_clientdata(client);
> > + int ret;
>
> > - i2c_smbus_write_byte_data(client,
> > + ret = i2c_smbus_write_byte_data(client,
> > pca95xx_num_input_regs(pca955x->chipdef->bits) + 4 + n,
> > val);
> > + if (ret < 0)
> > + dev_err(&client->dev, "%s: reg 0x%x, val 0x%x, err %d\n",
> > + __func__, n, val, ret);
> > + return ret;
> }
>
> /*
> * Read the LED selector register, which determines the source that
> * drives the LED output.
> */
> -static u8 pca955x_read_ls(struct i2c_client *client, int n)
> +static int pca955x_read_ls(struct i2c_client *client, int n, u8 *val)
> {
> > struct pca955x *pca955x = i2c_get_clientdata(client);
> > + int ret;
>
> > - return (u8) i2c_smbus_read_byte_data(client,
> > + ret = i2c_smbus_read_byte_data(client,
> > pca95xx_num_input_regs(pca955x->chipdef->bits) + 4 + n);
> > + if (ret < 0) {
> > + dev_err(&client->dev, "%s: reg 0x%x, err %d\n",
> > + __func__, n, ret);
> > + return ret;
> > + }
> > + *val = (u8)ret;
> > + return 0;
> }
>
> static int pca955x_led_set(struct led_classdev *led_cdev,
> @@ -223,6 +246,7 @@ static int pca955x_led_set(struct led_classdev *led_cdev,
> > u8 ls;
> > > int chip_ls; /* which LSx to use (0-3 potentially) */
> > > int ls_led; /* which set of bits within LSx to use (0-3) */
> > + int ret;
>
> > pca955x_led = container_of(led_cdev, struct pca955x_led, led_cdev);
> > pca955x = pca955x_led->pca955x;
> @@ -232,7 +256,9 @@ static int pca955x_led_set(struct led_classdev *led_cdev,
>
> > mutex_lock(&pca955x->lock);
>
> > - ls = pca955x_read_ls(pca955x->client, chip_ls);
> > + ret = pca955x_read_ls(pca955x->client, chip_ls, &ls);
> > + if (ret)
> > + goto out;
>
> > switch (value) {
> > case LED_FULL:
> @@ -252,26 +278,37 @@ static int pca955x_led_set(struct led_classdev *led_cdev,
> > * OFF, HALF, or FULL. But, this is probably better than
> > * just turning off for all other values.
> > */
> > - pca955x_write_pwm(pca955x->client, 1,
> > - 255 - value);
> > + ret = pca955x_write_pwm(pca955x->client, 1, 255 - value);
> > + if (ret)
> > + goto out;
> > ls = pca955x_ledsel(ls, ls_led, PCA955X_LS_BLINK1);
> > break;
> > }
>
> > - pca955x_write_ls(pca955x->client, chip_ls, ls);
> > + ret = pca955x_write_ls(pca955x->client, chip_ls, ls);
>
> +out:
> > mutex_unlock(&pca955x->lock);
>
> > - return 0;
> > + return ret;
> }
>
> #ifdef CONFIG_LEDS_PCA955X_GPIO
> /*
> * Read the INPUT register, which contains the state of LEDs.
> */
> -static u8 pca955x_read_input(struct i2c_client *client, int n)
> +static int pca955x_read_input(struct i2c_client *client, int n, u8 *val)
> {
> > - return (u8)i2c_smbus_read_byte_data(client, n);
> > + int ret = i2c_smbus_read_byte_data(client, n);
> +
> > + if (ret < 0) {
> > + dev_err(&client->dev, "%s: reg 0x%x, err %d\n",
> > + __func__, n, ret);
> > + return ret;
> > + }
> > + *val = (u8)ret;
> > + return 0;
> +
> }
>
> static int pca955x_gpio_request_pin(struct gpio_chip *gc, unsigned int offset)
> @@ -285,23 +322,32 @@ static int pca955x_gpio_request_pin(struct gpio_chip *gc, unsigned int offset)
> > return -EBUSY;
> }
>
> -static void pca955x_gpio_set_value(struct gpio_chip *gc, unsigned int offset,
> > - int val)
> +static int pca955x_set_value(struct gpio_chip *gc, unsigned int offset,
> > + int val)
> {
> > struct pca955x *pca955x = gpiochip_get_data(gc);
> > struct pca955x_led *led = &pca955x->leds[offset];
>
> > if (val)
> > - pca955x_led_set(&led->led_cdev, LED_FULL);
> > + return pca955x_led_set(&led->led_cdev, LED_FULL);
> > else
> > - pca955x_led_set(&led->led_cdev, LED_OFF);
> > + return pca955x_led_set(&led->led_cdev, LED_OFF);
> +}
> +
> +static void pca955x_gpio_set_value(struct gpio_chip *gc, unsigned int offset,
> > + int val)
> +{
> > + pca955x_set_value(gc, offset, val);
> }
>
> static int pca955x_gpio_get_value(struct gpio_chip *gc, unsigned int offset)
> {
> > struct pca955x *pca955x = gpiochip_get_data(gc);
> > struct pca955x_led *led = &pca955x->leds[offset];
> > - u8 reg = pca955x_read_input(pca955x->client, led->led_num / 8);
> > + u8 reg = 0;
> +
> > + /* There is nothing we can do about errors */
> > + pca955x_read_input(pca955x->client, led->led_num / 8, ®);
>
> > return !!(reg & (1 << (led->led_num % 8)));
> }
> @@ -310,17 +356,13 @@ static int pca955x_gpio_direction_input(struct gpio_chip *gc,
> > unsigned int offset)
> {
> > /* To use as input ensure pin is not driven */
> > - pca955x_gpio_set_value(gc, offset, 0);
> -
> > - return 0;
> > + return pca955x_set_value(gc, offset, 0);
> }
>
> static int pca955x_gpio_direction_output(struct gpio_chip *gc,
> > unsigned int offset, int val)
> {
> > - pca955x_gpio_set_value(gc, offset, val);
> -
> > - return 0;
> > + return pca955x_set_value(gc, offset, val);
> }
> #endif /* CONFIG_LEDS_PCA955X_GPIO */
>
> @@ -495,19 +537,29 @@ static int pca955x_probe(struct i2c_client *client,
> > return err;
>
> > /* Turn off LED */
> > - pca955x_led_set(&pca955x_led->led_cdev, LED_OFF);
> > + err = pca955x_led_set(&pca955x_led->led_cdev, LED_OFF);
> > + if (err)
> > + return err;
> > }
> > }
>
> > /* PWM0 is used for half brightness or 50% duty cycle */
> > - pca955x_write_pwm(client, 0, 255-LED_HALF);
> > + err = pca955x_write_pwm(client, 0, 255 - LED_HALF);
> > + if (err)
> > + return err;
>
> > /* PWM1 is used for variable brightness, default to OFF */
> > - pca955x_write_pwm(client, 1, 0);
> > + err = pca955x_write_pwm(client, 1, 0);
> > + if (err)
> > + return err;
>
> > /* Set to fast frequency so we do not see flashing */
> > - pca955x_write_psc(client, 0, 0);
> > - pca955x_write_psc(client, 1, 0);
> > + err = pca955x_write_psc(client, 0, 0);
> > + if (err)
> > + return err;
> > + err = pca955x_write_psc(client, 1, 0);
> > + if (err)
> > + return err;
>
> #ifdef CONFIG_LEDS_PCA955X_GPIO
> > if (ngpios) {
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