[PATCH v3] leds: pca9532: Propagate I2C errors

[Daniil Demakov <t3127430@gmail.com>]

Check return values from SMBus read and write operations and
propagate errors through LED, PWM, blink and GPIO operations.

Restore previous LED and PWM state when hardware updates fail.
Protect shared LED and PWM state with the update mutex.

Check register writes during device initialization and register
LED class devices only after successfully configuring the hardware.

Signed-off-by: Daniil Demakov <t3127430@gmail.com>
---
 drivers/leds/leds-pca9532.c | 313 ++++++++++++++++++++++++++++--------
 1 file changed, 250 insertions(+), 63 deletions(-)

diff --git a/drivers/leds/leds-pca9532.c b/drivers/leds/leds-pca9532.c
index c8085427696f..eb9020e77b46 100644
--- a/drivers/leds/leds-pca9532.c
+++ b/drivers/leds/leds-pca9532.c
@@ -144,68 +144,147 @@ static int pca9532_calcpwm(struct i2c_client *client, int pwm, int blink,
 	return 0;
 }
 
-static int pca9532_setpwm(struct i2c_client *client, int pwm)
+static int __pca9532_setpwm(struct i2c_client *client, int pwm)
 {
 	struct pca9532_data *data = i2c_get_clientdata(client);
 	u8 maxleds = data->chip_info->num_leds;
+	int ret;
 
-	mutex_lock(&data->update_lock);
-	i2c_smbus_write_byte_data(client, PCA9532_REG_PWM(maxleds, pwm),
-		data->pwm[pwm]);
-	i2c_smbus_write_byte_data(client, PCA9532_REG_PSC(maxleds, pwm),
-		data->psc[pwm]);
-	mutex_unlock(&data->update_lock);
-	return 0;
-}
+	if (pwm < 0 || pwm > 1)
+		return -EINVAL;
+
+	ret = i2c_smbus_write_byte_data(client,
+					PCA9532_REG_PWM(maxleds, pwm),
+					data->pwm[pwm]);
+	if (ret < 0) {
+		dev_warn(&client->dev,
+			 "Failed to write PWM register: %d\n", ret);
+		return ret;
+	}
 
+	ret = i2c_smbus_write_byte_data(client,
+					PCA9532_REG_PSC(maxleds, pwm),
+					data->psc[pwm]);
+	if (ret < 0)
+		dev_warn(&client->dev,
+			 "Failed to write PSC register: %d\n", ret);
+
+	return ret;
+}
 /* Set LED routing */
-static void pca9532_setled(struct pca9532_led *led)
+static int __pca9532_setled(struct pca9532_led *led)
 {
 	struct i2c_client *client = led->client;
 	struct pca9532_data *data = i2c_get_clientdata(client);
 	u8 maxleds = data->chip_info->num_leds;
-	char reg;
+	int reg;
+	int ret;
 
-	mutex_lock(&data->update_lock);
 	reg = i2c_smbus_read_byte_data(client, LED_REG(maxleds, led->id));
+	if (reg < 0) {
+		ret = reg;
+		dev_warn(&client->dev, "Failed to read LED register: %d\n", ret);
+		return ret;
+	}
+
 	/* zero led bits */
-	reg = reg & ~LED_MASK(led->id);
+	reg &= ~LED_MASK(led->id);
+
 	/* set the new value */
-	reg = reg | (led->state << LED_SHIFT(led->id));
-	i2c_smbus_write_byte_data(client, LED_REG(maxleds, led->id), reg);
+	reg |= led->state << LED_SHIFT(led->id);
+
+	ret = i2c_smbus_write_byte_data(client, LED_REG(maxleds, led->id), reg);
+
+	if (ret < 0)
+		dev_warn(&client->dev, "Failed to write LED register: %d\n", ret);
+
+	return ret;
+}
+
+static int pca9532_setled(struct pca9532_led *led)
+{
+	struct pca9532_data *data = i2c_get_clientdata(led->client);
+	int ret;
+
+	mutex_lock(&data->update_lock);
+	ret = __pca9532_setled(led);
 	mutex_unlock(&data->update_lock);
+
+	return ret;
 }
 
 static int pca9532_set_brightness(struct led_classdev *led_cdev,
-	enum led_brightness value)
+				  enum led_brightness value)
 {
-	int err = 0;
 	struct pca9532_led *led = ldev_to_led(led_cdev);
+	struct pca9532_data *data = i2c_get_clientdata(led->client);
+	int old_state;
+	u8 old_pwm;
+	u8 old_psc;
+	bool pwm_updated = false;
+	int restore_err;
+	int err = 0;
+
+	mutex_lock(&data->update_lock);
+	old_state = led->state;
+	old_pwm = data->pwm[PCA9532_PWM_ID_0];
+	old_psc = data->psc[PCA9532_PWM_ID_0];
 
 	if (value == LED_OFF) {
 		led->state = PCA9532_OFF;
 	} else if (led->state == PCA9532_PWM1) {
-		return 0; /* Non-zero brightness shall not stop HW blinking */
+		goto out;
 	} else if (value == LED_FULL) {
 		led->state = PCA9532_ON;
 	} else {
-		led->state = PCA9532_PWM0; /* Thecus: hardcode one pwm */
-		err = pca9532_calcpwm(led->client, PCA9532_PWM_ID_0, 0, value);
+		led->state = PCA9532_PWM0;
+		err = pca9532_calcpwm(led->client, PCA9532_PWM_ID_0,
+				      0, value);
 		if (err)
-			return err;
+			goto restore_state;
+	}
+
+	if (led->state == PCA9532_PWM0) {
+		pwm_updated = true;
+		err = __pca9532_setpwm(led->client, PCA9532_PWM_ID_0);
+		if (err < 0)
+			goto restore_state;
+	}
+
+	err = __pca9532_setled(led);
+	if (err < 0)
+		goto restore_state;
+
+	goto out;
+
+restore_state:
+	led->state = old_state;
+	data->pwm[PCA9532_PWM_ID_0] = old_pwm;
+	data->psc[PCA9532_PWM_ID_0] = old_psc;
+
+	if (pwm_updated) {
+		restore_err = __pca9532_setpwm(led->client,
+					       PCA9532_PWM_ID_0);
+		if (restore_err < 0)
+			dev_warn(&led->client->dev,
+				 "Failed to restore PWM settings: %d\n",
+				 restore_err);
 	}
-	if (led->state == PCA9532_PWM0)
-		pca9532_setpwm(led->client, PCA9532_PWM_ID_0);
-	pca9532_setled(led);
+out:
+	mutex_unlock(&data->update_lock);
 	return err;
 }
 
 static int pca9532_update_hw_blink(struct pca9532_led *led,
-				   unsigned long delay_on, unsigned long delay_off)
+				   unsigned long delay_on,
+				   unsigned long delay_off)
 {
 	struct pca9532_data *data = i2c_get_clientdata(led->client);
 	unsigned int psc;
-	int i;
+	unsigned long period;
+	u8 old_pwm = data->pwm[PCA9532_PWM_ID_1];
+	u8 old_psc = data->psc[PCA9532_PWM_ID_1];
+	int i, ret;
 
 	/* Look for others LEDs that already use PWM1 */
 	for (i = 0; i < data->chip_info->num_leds; i++) {
@@ -223,29 +302,64 @@ static int pca9532_update_hw_blink(struct pca9532_led *led,
 		}
 	}
 
-	psc = ((delay_on + delay_off) * PCA9532_PWM_PERIOD_DIV - 1) / 1000;
-	if (psc > U8_MAX) {
-		/* Blink period too long to be handled by hardware */
+	if (delay_on > ULONG_MAX - delay_off)
+		return -EINVAL;
+
+	period = delay_on + delay_off;
+
+	if (!delay_on || !delay_off)
 		return -EINVAL;
+
+	if (period > ((U8_MAX + 1) * 1000) /
+		     PCA9532_PWM_PERIOD_DIV)
+		return -EINVAL;
+
+	psc = (period * PCA9532_PWM_PERIOD_DIV - 1) / 1000;
+
+	data->psc[PCA9532_PWM_ID_1] = psc;
+	data->pwm[PCA9532_PWM_ID_1] =
+		(delay_on * PCA9532_PWM_DUTY_DIV) / period;
+
+	ret = __pca9532_setpwm(data->client, PCA9532_PWM_ID_1);
+	if (ret < 0) {
+		data->pwm[PCA9532_PWM_ID_1] = old_pwm;
+		data->psc[PCA9532_PWM_ID_1] = old_psc;
+
+		if (__pca9532_setpwm(data->client, PCA9532_PWM_ID_1) < 0)
+			dev_warn(&data->client->dev,
+				 "Failed to restore PWM settings\n");
+
+		return ret;
 	}
 
 	led->state = PCA9532_PWM1;
-	data->psc[PCA9532_PWM_ID_1] = psc;
-	data->pwm[PCA9532_PWM_ID_1] = (delay_on * PCA9532_PWM_DUTY_DIV) / (delay_on + delay_off);
 
-	return pca9532_setpwm(data->client, PCA9532_PWM_ID_1);
+	return 0;
 }
 
 static int pca9532_set_blink(struct led_classdev *led_cdev,
-	unsigned long *delay_on, unsigned long *delay_off)
+			     unsigned long *delay_on,
+			     unsigned long *delay_off)
 {
 	struct pca9532_led *led = ldev_to_led(led_cdev);
 	struct i2c_client *client = led->client;
 	struct pca9532_data *data = i2c_get_clientdata(client);
+	int old_state;
+	int restore_err;
+	u8 old_pwm;
+	u8 old_psc;
 	int err;
 
-	if (!data->hw_blink)
-		return -EINVAL;
+	mutex_lock(&data->update_lock);
+
+	old_state = led->state;
+	old_pwm = data->pwm[PCA9532_PWM_ID_1];
+	old_psc = data->psc[PCA9532_PWM_ID_1];
+
+	if (!data->hw_blink) {
+		err = -EINVAL;
+		goto out;
+	}
 
 	if (*delay_on == 0 && *delay_off == 0) {
 		/* led subsystem ask us for a blink rate */
@@ -255,15 +369,32 @@ static int pca9532_set_blink(struct led_classdev *led_cdev,
 
 	err = pca9532_update_hw_blink(led, *delay_on, *delay_off);
 	if (err)
-		return err;
+		goto restore_state;
+
+	err = __pca9532_setled(led);
+	if (err < 0) {
+		led->state = old_state;
+		data->pwm[PCA9532_PWM_ID_1] = old_pwm;
+		data->psc[PCA9532_PWM_ID_1] = old_psc;
+
+		restore_err = __pca9532_setpwm(client, PCA9532_PWM_ID_1);
+		if (restore_err < 0)
+			dev_warn(&client->dev,
+				 "Failed to restore PWM settings: %d\n",
+				 restore_err);
+	}
 
-	pca9532_setled(led);
+	goto out;
 
-	return 0;
+restore_state:
+	led->state = old_state;
+out:
+	mutex_unlock(&data->update_lock);
+	return err;
 }
 
 static int pca9532_event(struct input_dev *dev, unsigned int type,
-	unsigned int code, int value)
+			 unsigned int code, int value)
 {
 	struct pca9532_data *data = input_get_drvdata(dev);
 
@@ -271,11 +402,15 @@ static int pca9532_event(struct input_dev *dev, unsigned int type,
 		return -1;
 
 	/* XXX: allow different kind of beeps with psc/pwm modifications */
+	mutex_lock(&data->update_lock);
+
 	if (value > 1 && value < 32767)
 		data->pwm[PCA9532_PWM_ID_1] = 127;
 	else
 		data->pwm[PCA9532_PWM_ID_1] = 0;
 
+	mutex_unlock(&data->update_lock);
+
 	schedule_work(&data->work);
 
 	return 0;
@@ -286,27 +421,36 @@ static void pca9532_input_work(struct work_struct *work)
 	struct pca9532_data *data =
 		container_of(work, struct pca9532_data, work);
 	u8 maxleds = data->chip_info->num_leds;
+	int ret;
 
 	mutex_lock(&data->update_lock);
-	i2c_smbus_write_byte_data(data->client, PCA9532_REG_PWM(maxleds, 1),
-		data->pwm[PCA9532_PWM_ID_1]);
+	ret = i2c_smbus_write_byte_data(data->client,
+					PCA9532_REG_PWM(maxleds, 1),
+					data->pwm[PCA9532_PWM_ID_1]);
+	if (ret < 0)
+		dev_warn(&data->client->dev,
+			 "Failed to write PWM register: %d\n", ret);
+
 	mutex_unlock(&data->update_lock);
 }
 
-static enum pca9532_state pca9532_getled(struct pca9532_led *led)
+static int pca9532_getled(struct pca9532_led *led)
 {
 	struct i2c_client *client = led->client;
 	struct pca9532_data *data = i2c_get_clientdata(client);
 	u8 maxleds = data->chip_info->num_leds;
 	int reg;
-	enum pca9532_state ret = PCA9532_OFF;
+	int ret;
 
 	mutex_lock(&data->update_lock);
 	reg = i2c_smbus_read_byte_data(client, LED_REG(maxleds, led->id));
-	if (reg >= 0)
+
+	if (reg >= 0) {
 		ret = (reg & LED_MASK(led->id)) >> LED_SHIFT(led->id);
-	else
-		dev_warn(&client->dev, "failed to read LED register: %d\n", reg);
+	} else {
+		ret = reg;
+		dev_warn(&client->dev, "Failed to read LED register: %d\n", ret);
+	}
 	mutex_unlock(&data->update_lock);
 	return ret;
 }
@@ -328,33 +472,42 @@ static int pca9532_gpio_set_value(struct gpio_chip *gc, unsigned int offset,
 {
 	struct pca9532_data *data = gpiochip_get_data(gc);
 	struct pca9532_led *led = &data->leds[offset];
+	int old_state;
+	int ret;
+
+	mutex_lock(&data->update_lock);
+	old_state = led->state;
 
 	if (val)
 		led->state = PCA9532_OFF;
 	else
 		led->state = PCA9532_ON;
 
-	pca9532_setled(led);
+	ret = __pca9532_setled(led);
+	if (ret < 0)
+		led->state = old_state;
 
-	return 0;
+	mutex_unlock(&data->update_lock);
+
+	return ret;
 }
 
 static int pca9532_gpio_get_value(struct gpio_chip *gc, unsigned offset)
 {
 	struct pca9532_data *data = gpiochip_get_data(gc);
-	unsigned char reg;
+	int reg;
 
 	reg = i2c_smbus_read_byte_data(data->client, PCA9532_REG_INPUT(offset));
 
+	if (reg < 0)
+		return reg;
+
 	return !!(reg & (1 << (offset % 8)));
 }
 
 static int pca9532_gpio_direction_input(struct gpio_chip *gc, unsigned offset)
 {
-	/* To use as input ensure pin is not driven */
-	pca9532_gpio_set_value(gc, offset, 1);
-
-	return 0;
+	return pca9532_gpio_set_value(gc, offset, 1);
 }
 
 static int pca9532_gpio_direction_output(struct gpio_chip *gc, unsigned offset, int val)
@@ -394,40 +547,57 @@ static int pca9532_configure(struct i2c_client *client,
 	struct pca9532_data *data, struct pca9532_platform_data *pdata)
 {
 	int i, err = 0;
+#ifdef CONFIG_LEDS_PCA9532_GPIO
 	int gpios = 0;
+#endif
 	u8 maxleds = data->chip_info->num_leds;
 
-	for (i = 0; i < 2; i++)	{
+	for (i = 0; i < 2; i++) {
 		data->pwm[i] = pdata->pwm[i];
 		data->psc[i] = pdata->psc[i];
-		err = i2c_smbus_write_byte_data(client, PCA9532_REG_PWM(maxleds, i),
+
+		err = i2c_smbus_write_byte_data(client,
+						PCA9532_REG_PWM(maxleds, i),
 						data->pwm[i]);
 		if (err < 0)
 			return err;
-		err = i2c_smbus_write_byte_data(client, PCA9532_REG_PSC(maxleds, i),
+
+		err = i2c_smbus_write_byte_data(client,
+						PCA9532_REG_PSC(maxleds, i),
 						data->psc[i]);
 		if (err < 0)
 			return err;
 	}
 
 	data->hw_blink = true;
+
 	for (i = 0; i < data->chip_info->num_leds; i++) {
 		struct pca9532_led *led = &data->leds[i];
 		struct pca9532_led *pled = &pdata->leds[i];
+
 		led->client = client;
 		led->id = i;
 		led->type = pled->type;
+
 		switch (led->type) {
 		case PCA9532_TYPE_NONE:
 			break;
 		case PCA9532_TYPE_GPIO:
+#ifdef CONFIG_LEDS_PCA9532_GPIO
 			gpios++;
+#endif
 			break;
 		case PCA9532_TYPE_LED:
-			if (pled->state == PCA9532_KEEP)
-				led->state = pca9532_getled(led);
-			else
+			if (pled->state == PCA9532_KEEP) {
+				err = pca9532_getled(led);
+				if (err < 0)
+					goto exit;
+
+				led->state = err;
+			} else {
 				led->state = pled->state;
+			}
+
 			led->name = pled->name;
 			led->ldev.name = led->name;
 			led->ldev.default_trigger = pled->default_trigger;
@@ -435,6 +605,15 @@ static int pca9532_configure(struct i2c_client *client,
 			led->ldev.brightness_set_blocking =
 						pca9532_set_brightness;
 			led->ldev.blink_set = pca9532_set_blink;
+
+			err = pca9532_setled(led);
+			if (err < 0) {
+				dev_err(&client->dev,
+					"couldn't set LED %s state\n",
+					led->name);
+				goto exit;
+			}
+
 			err = led_classdev_register(&client->dev, &led->ldev);
 			if (err < 0) {
 				dev_err(&client->dev,
@@ -442,19 +621,26 @@ static int pca9532_configure(struct i2c_client *client,
 					led->name);
 				goto exit;
 			}
-			pca9532_setled(led);
 			break;
 		case PCA9532_TYPE_N2100_BEEP:
 			/* PWM1 is reserved for beeper so blink will not use hardware */
 			data->hw_blink = false;
 			BUG_ON(data->idev);
+
 			led->state = PCA9532_PWM1;
-			pca9532_setled(led);
+			err = pca9532_setled(led);
+			if (err < 0) {
+				dev_err(&client->dev,
+					"couldn't set beeper state\n");
+				goto exit;
+			}
+
 			data->idev = devm_input_allocate_device(&client->dev);
 			if (data->idev == NULL) {
 				err = -ENOMEM;
 				goto exit;
 			}
+
 			data->idev->name = pled->name;
 			data->idev->phys = "i2c/pca9532";
 			data->idev->id.bustype = BUS_HOST;
@@ -467,6 +653,7 @@ static int pca9532_configure(struct i2c_client *client,
 			data->idev->event = pca9532_event;
 			input_set_drvdata(data->idev, data);
 			INIT_WORK(&data->work, pca9532_input_work);
+
 			err = input_register_device(data->idev);
 			if (err) {
 				cancel_work_sync(&data->work);
@@ -498,8 +685,8 @@ static int pca9532_configure(struct i2c_client *client,
 			dev_warn(&client->dev, "could not add gpiochip\n");
 		} else {
 			dev_info(&client->dev, "gpios %i...%i\n",
-				data->gpio.base, data->gpio.base +
-				data->gpio.ngpio - 1);
+				 data->gpio.base, data->gpio.base +
+				 data->gpio.ngpio - 1);
 		}
 	}
 #endif
-- 
2.56.0