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Subject[PATCH v4 6/6] leds: lm3692x: Allow to configure brigthness mode
Date
Brightness mode is currently hardcoded as linear in the driver. Make
exponential mode configurable via DT.

Signed-off-by: Guido Günther <agx@sigxcpu.org>
---
drivers/leds/leds-lm3692x.c | 17 ++++++++++++++---
1 file changed, 14 insertions(+), 3 deletions(-)

diff --git a/drivers/leds/leds-lm3692x.c b/drivers/leds/leds-lm3692x.c
index 28a51aeb28de..933b786cfaec 100644
--- a/drivers/leds/leds-lm3692x.c
+++ b/drivers/leds/leds-lm3692x.c
@@ -239,8 +239,7 @@ static int lm3692x_leds_enable(struct lm3692x_led *led)
if (ret)
goto out;

- ret = regmap_write(led->regmap, LM3692X_BRT_CTRL,
- LM3692X_BL_ADJ_POL | LM3692X_RAMP_EN);
+ ret = regmap_write(led->regmap, LM3692X_BRT_CTRL, led->brightness_ctrl);
if (ret)
goto out;

@@ -368,7 +367,12 @@ static enum led_brightness lm3692x_max_brightness(struct lm3692x_led *led,
u32 max_code;

/* see p.12 of LM36922 data sheet for brightness formula */
- max_code = ((max_cur * 1000) - 37806) / 12195;
+ if (led->brightness_ctrl & LM3692X_MAP_MODE_EXP) {
+ /* 228 =~ 1.0 / log2(1.003040572) */
+ max_code = ilog2(max_cur/50) * 228;
+ } else {
+ max_code = ((max_cur * 1000) - 37806) / 12195;
+ }
if (max_code > 0x7FF)
max_code = 0x7FF;

@@ -380,6 +384,7 @@ static int lm3692x_probe_dt(struct lm3692x_led *led)
struct fwnode_handle *child = NULL;
struct led_init_data init_data = {};
u32 ovp, max_cur;
+ bool exp_mode;
int ret;

led->enable_gpio = devm_gpiod_get_optional(&led->client->dev,
@@ -430,6 +435,12 @@ static int lm3692x_probe_dt(struct lm3692x_led *led)
}
}

+ led->brightness_ctrl = LM3692X_BL_ADJ_POL | LM3692X_RAMP_EN;
+ exp_mode = device_property_read_bool(&led->client->dev,
+ "ti,brightness-mapping-exponential");
+ if (exp_mode)
+ led->brightness_ctrl |= LM3692X_MAP_MODE_EXP;
+
child = device_get_next_child_node(&led->client->dev, child);
if (!child) {
dev_err(&led->client->dev, "No LED Child node\n");
--
2.23.0
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