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Subject[PATCH 2/2] leds: lp55xx: add option to disable charge pump
Date
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.

While undocumented, it is possible to connect an external power
rail to the Vout pin on the device to save power. However, when
doing this, the internal charge pump needs to be disabled. If
it is enabled in this configuration, there is leakage from the
externally supplied Vout back to Vin (Vdd).

This commit adds an option in the devicetree to disable the
charge pump. When the option is not present, the device config
is exactly as before (automatic mode).

Tested on LP55231. Datasheet analysis shows that LP5521, LP5523
and LP8501 are identical in topology and have been modified in
the same way.

Signed-off-by: Maarten Zanders <maarten.zanders@mind.be>
---
drivers/leds/leds-lp5521.c | 6 ++++--
drivers/leds/leds-lp5523.c | 15 +++++++++++----
drivers/leds/leds-lp55xx-common.c | 3 +++
drivers/leds/leds-lp8501.c | 5 ++++-
include/linux/platform_data/leds-lp55xx.h | 3 +++
5 files changed, 25 insertions(+), 7 deletions(-)

diff --git a/drivers/leds/leds-lp5521.c b/drivers/leds/leds-lp5521.c
index 7ff20c260504..80f3b50c9502 100644
--- a/drivers/leds/leds-lp5521.c
+++ b/drivers/leds/leds-lp5521.c
@@ -64,8 +64,7 @@
#define LP5521_CP_MODE_AUTO 0x18 /* Automatic mode selection */
#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 +309,9 @@ static int lp5521_post_init_device(struct lp55xx_chip *chip)
if (!lp55xx_is_extclk_used(chip))
val |= LP5521_CLK_INT;

+ if (!chip->pdata->cp_disable)
+ val |= LP5521_CP_MODE_AUTO;
+
ret = lp55xx_write(chip, LP5521_REG_CONFIG, val);
if (ret)
return ret;
diff --git a/drivers/leds/leds-lp5523.c b/drivers/leds/leds-lp5523.c
index 369d40b0b65b..06d81a520168 100644
--- a/drivers/leds/leds-lp5523.c
+++ b/drivers/leds/leds-lp5523.c
@@ -59,6 +59,9 @@
#define LP5523_PWM_PWR_SAVE 0x04
#define LP5523_CP_AUTO 0x18
#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 +137,13 @@ 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;
+
+ if (!chip->pdata->cp_disable)
+ val |= LP5523_CP_AUTO;
+
+ ret = lp55xx_write(chip, LP5523_REG_CONFIG, val);
+
if (ret)
return ret;

diff --git a/drivers/leds/leds-lp55xx-common.c b/drivers/leds/leds-lp55xx-common.c
index ca2e28fb843f..aadaca26fb23 100644
--- a/drivers/leds/leds-lp55xx-common.c
+++ b/drivers/leds/leds-lp55xx-common.c
@@ -691,6 +691,9 @@ struct lp55xx_platform_data *lp55xx_of_populate_pdata(struct device *dev,
i++;
}

+ if (of_find_property(np, "ti,disable-charge-pump", NULL))
+ pdata->cp_disable = 1;
+
of_property_read_string(np, "label", &pdata->label);
of_property_read_u8(np, "clock-mode", &pdata->clock_mode);

diff --git a/drivers/leds/leds-lp8501.c b/drivers/leds/leds-lp8501.c
index ae11a02c0ab2..6370abb2c7ae 100644
--- a/drivers/leds/leds-lp8501.c
+++ b/drivers/leds/leds-lp8501.c
@@ -56,7 +56,7 @@
#define LP8501_CP_AUTO 0x18
#define LP8501_INT_CLK BIT(0)
#define LP8501_DEFAULT_CFG \
- (LP8501_PWM_PSAVE | LP8501_AUTO_INC | LP8501_PWR_SAVE | LP8501_CP_AUTO)
+ (LP8501_PWM_PSAVE | LP8501_AUTO_INC | LP8501_PWR_SAVE)

#define LP8501_REG_RESET 0x3D
#define LP8501_RESET 0xFF
@@ -102,6 +102,9 @@ static int lp8501_post_init_device(struct lp55xx_chip *chip)
if (chip->pdata->clock_mode != LP55XX_CLOCK_EXT)
val |= LP8501_INT_CLK;

+ if (!chip->pdata->cp_disable)
+ val |= LP8501_CP_AUTO;
+
ret = lp55xx_write(chip, LP8501_REG_CONFIG, val);
if (ret)
return ret;
diff --git a/include/linux/platform_data/leds-lp55xx.h b/include/linux/platform_data/leds-lp55xx.h
index 3441064713a3..8e2ba5e2a7ee 100644
--- a/include/linux/platform_data/leds-lp55xx.h
+++ b/include/linux/platform_data/leds-lp55xx.h
@@ -73,6 +73,9 @@ struct lp55xx_platform_data {
/* Clock configuration */
u8 clock_mode;

+ /* charge pump disable */
+ u8 cp_disable;
+
/* optional enable GPIO */
struct gpio_desc *enable_gpiod;

--
2.37.3
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