[PATCH v1] leds: pca9532: correct shift computation in pca9532_getled

* [PATCH v1] leds: pca9532: correct shift computation in pca9532_getled
@ 2020-09-22 19:28 Markus Moll
  2020-09-24 12:24 ` Pavel Machek
  0 siblings, 1 reply; 4+ messages in thread
From: Markus Moll @ 2020-09-22 19:28 UTC (permalink / raw)
  To: Riku Voipio, Pavel Machek, Dan Murphy; +Cc: linux-leds

Each led setting occupies two bits in a corresponding led register.
Accessing these bits requires shifting and masking, which was
implemented incorrectly in pca9532_getled. Two new helper macros
concentrate the computation of those masks in one place.

Signed-off-by: Markus Moll <mmoll@de.pepperl-fuchs.com>
---
 drivers/leds/leds-pca9532.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/drivers/leds/leds-pca9532.c b/drivers/leds/leds-pca9532.c
index 41229f775d3..d37fd9577d4 100644
--- a/drivers/leds/leds-pca9532.c
+++ b/drivers/leds/leds-pca9532.c
@@ -27,6 +27,8 @@
 #define PCA9532_REG_PWM(m, i)	(PCA9532_REG_OFFSET(m) + 0x2 + (i) * 2)
 #define LED_REG(m, led)		(PCA9532_REG_OFFSET(m) + 0x5 + (led >> 2))
 #define LED_NUM(led)		(led & 0x3)
+#define LED_SHIFT(led)		(LED_NUM(led) * 2)
+#define LED_MASK(led)		(0x3 << LED_SHIFT(led))
 
 #define ldev_to_led(c)       container_of(c, struct pca9532_led, ldev)
 
@@ -162,9 +164,9 @@ static void pca9532_setled(struct pca9532_led *led)
 	mutex_lock(&data->update_lock);
 	reg = i2c_smbus_read_byte_data(client, LED_REG(maxleds, led->id));
 	/* zero led bits */
-	reg = reg & ~(0x3<<LED_NUM(led->id)*2);
+	reg = reg & ~LED_MASK(led->id);
 	/* set the new value */
-	reg = reg | (led->state << LED_NUM(led->id)*2);
+	reg = reg | (led->state << LED_SHIFT(led->id));
 	i2c_smbus_write_byte_data(client, LED_REG(maxleds, led->id), reg);
 	mutex_unlock(&data->update_lock);
 }
@@ -260,7 +262,7 @@ static enum pca9532_state pca9532_getled(struct pca9532_led *led)
 
 	mutex_lock(&data->update_lock);
 	reg = i2c_smbus_read_byte_data(client, LED_REG(maxleds, led->id));
-	ret = reg >> LED_NUM(led->id)/2;
+	ret = (reg & LED_MASK(led->id)) >> LED_SHIFT(led->id);
 	mutex_unlock(&data->update_lock);
 	return ret;
 }
-- 
2.25.1

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