leds: lp55xx: Configure internal charge pump

The LP55xx range of devices have an internal charge pump which
can (automatically) increase the output voltage towards the
LED's, boosting the output voltage to 4.5V.

Implement this option from the devicetree. When the setting
is not present it will operate in automatic mode as before.

Tested on LP55231. Datasheet analysis shows that LP5521, LP5523
and LP8501 are identical in topology and are modified in the
same way.
Signed-off-by: Maarten Zanders <maarten.zanders@mind.be>
Signed-off-by: Lee Jones <lee@kernel.org>
Link: https://lore.kernel.org/r/20230421075305.37597-3-maarten.zanders@mind.be

drivers/leds/leds-lp5521.c

@@ -58,14 +58,11 @@
 /* CONFIG register */
 #define LP5521_PWM_HF			0x40	/* PWM: 0 = 256Hz, 1 = 558Hz */
 #define LP5521_PWRSAVE_EN		0x20	/* 1 = Power save mode */
-#define LP5521_CP_MODE_OFF		0	/* Charge pump (CP) off */
-#define LP5521_CP_MODE_BYPASS		8	/* CP forced to bypass mode */
-#define LP5521_CP_MODE_1X5		0x10	/* CP forced to 1.5x mode */
-#define LP5521_CP_MODE_AUTO		0x18	/* Automatic mode selection */
+#define LP5521_CP_MODE_MASK		0x18	/* Charge pump mode */
+#define LP5521_CP_MODE_SHIFT		3
 #define LP5521_R_TO_BATT		0x04	/* R out: 0 = CP, 1 = Vbat */
 #define LP5521_CLK_INT			0x01	/* Internal clock */
-#define LP5521_DEFAULT_CFG		\
-	(LP5521_PWM_HF | LP5521_PWRSAVE_EN | LP5521_CP_MODE_AUTO)
+#define LP5521_DEFAULT_CFG		(LP5521_PWM_HF | LP5521_PWRSAVE_EN)
 
 /* Status */
 #define LP5521_EXT_CLK_USED		0x08
@@ -310,6 +307,8 @@ static int lp5521_post_init_device(struct lp55xx_chip *chip)
 	if (!lp55xx_is_extclk_used(chip))
 		val |= LP5521_CLK_INT;
 
+	val |= (chip->pdata->charge_pump_mode << LP5521_CP_MODE_SHIFT) & LP5521_CP_MODE_MASK;
+
 	ret = lp55xx_write(chip, LP5521_REG_CONFIG, val);
 	if (ret)
 		return ret;

drivers/leds/leds-lp5523.c

@@ -57,8 +57,11 @@
 #define LP5523_AUTO_INC			0x40
 #define LP5523_PWR_SAVE			0x20
 #define LP5523_PWM_PWR_SAVE		0x04
-#define LP5523_CP_AUTO			0x18
+#define LP5523_CP_MODE_MASK		0x18
+#define LP5523_CP_MODE_SHIFT		3
 #define LP5523_AUTO_CLK			0x02
+#define LP5523_DEFAULT_CONFIG \
+	(LP5523_AUTO_INC | LP5523_PWR_SAVE | LP5523_AUTO_CLK | LP5523_PWM_PWR_SAVE)
 
 #define LP5523_EN_LEDTEST		0x80
 #define LP5523_LEDTEST_DONE		0x80
@@ -125,6 +128,7 @@ static void lp5523_set_led_current(struct lp55xx_led *led, u8 led_current)
 static int lp5523_post_init_device(struct lp55xx_chip *chip)
 {
 	int ret;
+	int val;
 
 	ret = lp55xx_write(chip, LP5523_REG_ENABLE, LP5523_ENABLE);
 	if (ret)
@@ -133,10 +137,10 @@ static int lp5523_post_init_device(struct lp55xx_chip *chip)
 	/* Chip startup time is 500 us, 1 - 2 ms gives some margin */
 	usleep_range(1000, 2000);
 
-	ret = lp55xx_write(chip, LP5523_REG_CONFIG,
-			    LP5523_AUTO_INC | LP5523_PWR_SAVE |
-			    LP5523_CP_AUTO | LP5523_AUTO_CLK |
-			    LP5523_PWM_PWR_SAVE);
+	val = LP5523_DEFAULT_CONFIG;
+	val |= (chip->pdata->charge_pump_mode << LP5523_CP_MODE_SHIFT) & LP5523_CP_MODE_MASK;
+
+	ret = lp55xx_write(chip, LP5523_REG_CONFIG, val);
 	if (ret)
 		return ret;
 

drivers/leds/leds-lp55xx-common.c

@@ -18,6 +18,7 @@
 #include <linux/platform_data/leds-lp55xx.h>
 #include <linux/slab.h>
 #include <linux/gpio/consumer.h>
+#include <dt-bindings/leds/leds-lp55xx.h>
 
 #include "leds-lp55xx-common.h"
 
@@ -691,6 +692,14 @@ struct lp55xx_platform_data *lp55xx_of_populate_pdata(struct device *dev,
 		i++;
 	}
 
+	if (of_property_read_u32(np, "ti,charge-pump-mode", &pdata->charge_pump_mode))
+		pdata->charge_pump_mode = LP55XX_CP_AUTO;
+
+	if (pdata->charge_pump_mode > LP55XX_CP_AUTO) {
+		dev_err(dev, "invalid charge pump mode %d\n", pdata->charge_pump_mode);
+		return ERR_PTR(-EINVAL);
+	}
+
 	of_property_read_string(np, "label", &pdata->label);
 	of_property_read_u8(np, "clock-mode", &pdata->clock_mode);
 

drivers/leds/leds-lp8501.c

@@ -53,10 +53,10 @@
 #define LP8501_PWM_PSAVE		BIT(7)
 #define LP8501_AUTO_INC			BIT(6)
 #define LP8501_PWR_SAVE			BIT(5)
-#define LP8501_CP_AUTO			0x18
+#define LP8501_CP_MODE_MASK		0x18
+#define LP8501_CP_MODE_SHIFT		3
 #define LP8501_INT_CLK			BIT(0)
-#define LP8501_DEFAULT_CFG	\
-	(LP8501_PWM_PSAVE | LP8501_AUTO_INC | LP8501_PWR_SAVE | LP8501_CP_AUTO)
+#define LP8501_DEFAULT_CFG (LP8501_PWM_PSAVE | LP8501_AUTO_INC | LP8501_PWR_SAVE)
 
 #define LP8501_REG_RESET		0x3D
 #define LP8501_RESET			0xFF
@@ -102,6 +102,8 @@ static int lp8501_post_init_device(struct lp55xx_chip *chip)
 	if (chip->pdata->clock_mode != LP55XX_CLOCK_EXT)
 		val |= LP8501_INT_CLK;
 
+	val |= (chip->pdata->charge_pump_mode << LP8501_CP_MODE_SHIFT) & LP8501_CP_MODE_MASK;
+
 	ret = lp55xx_write(chip, LP8501_REG_CONFIG, val);
 	if (ret)
 		return ret;

include/linux/platform_data/leds-lp55xx.h

@@ -73,6 +73,9 @@ struct lp55xx_platform_data {
 	/* Clock configuration */
 	u8 clock_mode;
 
+	/* Charge pump mode */
+	u32 charge_pump_mode;
+
 	/* optional enable GPIO */
 	struct gpio_desc *enable_gpiod;