* [PATCH 2/2 v7] leds: rt8515: Add Richtek RT8515 LED driver
2020-12-01 10:13 [PATCH 1/2 v7] dt-bindings: leds: Add DT binding for Richtek RT8515 Linus Walleij
@ 2020-12-01 10:13 ` Linus Walleij
2020-12-30 19:09 ` Pavel Machek
2020-12-30 20:32 ` Andy Shevchenko
2020-12-09 16:31 ` [PATCH 1/2 v7] dt-bindings: leds: Add DT binding for Richtek RT8515 Rob Herring
1 sibling, 2 replies; 6+ messages in thread
From: Linus Walleij @ 2020-12-01 10:13 UTC (permalink / raw)
To: Jacek Anaszewski, Pavel Machek, Dan Murphy
Cc: linux-leds, Linus Walleij, Sakari Ailus, newbytee,
Stephan Gerhold, linux-media, phone-devel, Sakari Ailus
This adds a driver for the Richtek RT8515 dual channel
torch/flash white LED driver.
This LED driver is found in some mobile phones from
Samsung such as the GT-S7710 and GT-I8190.
A V4L interface is added.
We do not have a proper datasheet for the RT8515 but
it turns out that RT9387A has a public datasheet and
is essentially the same chip. We designed the driver
in accordance with this datasheet. The day someone
needs to drive a RT9387A this driver can probably
easily be augmented to handle that chip too.
Cc: Sakari Ailus <sakari.ailus@iki.fi>
Cc: newbytee@protonmail.com
Cc: Stephan Gerhold <stephan@gerhold.net>
Cc: linux-media@vger.kernel.org
Cc: phone-devel@vger.kernel.org
Reviewed-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
---
ChangeLog v6->v7:
- Account for the binding change to use led-max-current
rather than torch-specific current.
- Collect Sakari's review tag.
ChangeLog v5->v6:
- Use the configured max flash brightness instead of
hardcoded "4".
- Implement the new "-ohms" suffixes on the resistors.
ChangeLog v4->v5:
- Fix a missing static keyword, complaint from the kernel
autobuilder robot.
ChangeLog v3->v4:
- Create a new subdirectory for flash LEDs under
drivers/leds/flash as requested by Pavel, move the
driver there and set up a kbuild structure for pure
flash LEDs.
(Others can follow the established pattern.)
- Handle the new richtek,rfs and richtek,rts resistor
values that make it possible to determine the current
range configured in the hardware.
- Handle the new flash-max-microamp and torch-max-microamp
if present and optionally further restrict the current
range using these. Otherwise fall back on the hardware
defaults as specified by the RFS and RTS resistors.
- Cc phone-devel@vger.kernel.org
- License as GPL-2.0-or-later
- Renable ent and enf gpio descriptors to enable_torch
and enable_flash
Changelog v2->v3:
- Expand commit message.
- Add Sakari to Cc.
- Resend.
ChangeLog v1->v2:
- Break out routine to bitbang the brightness on a
GPIO pin.
- Do not hardcode the LED name so that the framework
can name it from DT properties.
---
drivers/leds/Kconfig | 3 +
drivers/leds/Makefile | 3 +
drivers/leds/flash/Kconfig | 15 ++
drivers/leds/flash/Makefile | 3 +
drivers/leds/flash/leds-rt8515.c | 377 +++++++++++++++++++++++++++++++
5 files changed, 401 insertions(+)
create mode 100644 drivers/leds/flash/Kconfig
create mode 100644 drivers/leds/flash/Makefile
create mode 100644 drivers/leds/flash/leds-rt8515.c
diff --git a/drivers/leds/Kconfig b/drivers/leds/Kconfig
index 849d3c5f908e..6c1d8b69a465 100644
--- a/drivers/leds/Kconfig
+++ b/drivers/leds/Kconfig
@@ -928,6 +928,9 @@ config LEDS_ACER_A500
This option enables support for the Power Button LED of
Acer Iconia Tab A500.
+comment "Flash and Torch LED drivers"
+source "drivers/leds/flash/Kconfig"
+
comment "LED Triggers"
source "drivers/leds/trigger/Kconfig"
diff --git a/drivers/leds/Makefile b/drivers/leds/Makefile
index 73e603e1727e..156c0b4e60d9 100644
--- a/drivers/leds/Makefile
+++ b/drivers/leds/Makefile
@@ -103,5 +103,8 @@ obj-$(CONFIG_LEDS_SPI_BYTE) += leds-spi-byte.o
# LED Userspace Drivers
obj-$(CONFIG_LEDS_USER) += uleds.o
+# Flash and Torch LED Drivers
+obj-$(CONFIG_LEDS_CLASS_FLASH) += flash/
+
# LED Triggers
obj-$(CONFIG_LEDS_TRIGGERS) += trigger/
diff --git a/drivers/leds/flash/Kconfig b/drivers/leds/flash/Kconfig
new file mode 100644
index 000000000000..d21d273ef3da
--- /dev/null
+++ b/drivers/leds/flash/Kconfig
@@ -0,0 +1,15 @@
+# SPDX-License-Identifier: GPL-2.0
+
+if LEDS_CLASS_FLASH
+
+config LEDS_RT8515
+ tristate "LED support for Richtek RT8515 flash/torch LED"
+ depends on GPIOLIB
+ help
+ This option enables support for the Richtek RT8515 flash
+ and torch LEDs found on some mobile phones.
+
+ To compile this driver as a module, choose M here: the module
+ will be called leds-rt8515.
+
+endif # LEDS_CLASS_FLASH
diff --git a/drivers/leds/flash/Makefile b/drivers/leds/flash/Makefile
new file mode 100644
index 000000000000..e990e257f4d7
--- /dev/null
+++ b/drivers/leds/flash/Makefile
@@ -0,0 +1,3 @@
+# SPDX-License-Identifier: GPL-2.0
+
+obj-$(CONFIG_LEDS_RT8515) += leds-rt8515.o
diff --git a/drivers/leds/flash/leds-rt8515.c b/drivers/leds/flash/leds-rt8515.c
new file mode 100644
index 000000000000..113db986cc64
--- /dev/null
+++ b/drivers/leds/flash/leds-rt8515.c
@@ -0,0 +1,377 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * LED driver for Richtek RT8515 flash/torch white LEDs
+ * found on some Samsung mobile phones.
+ * This is a 1.5A Boost dual channel driver produced around 2011.
+ *
+ * Linus Walleij <linus.walleij@linaro.org>
+ */
+#include <linux/delay.h>
+#include <linux/err.h>
+#include <linux/gpio/consumer.h>
+#include <linux/led-class-flash.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/regulator/consumer.h>
+
+#include <media/v4l2-flash-led-class.h>
+
+/* We can provide 15-700 mA out to the LED */
+#define RT8515_MIN_IOUT_MA 15
+#define RT8515_MAX_IOUT_MA 700
+/* The maximum intensity is 1-16 for flash and 1-100 for torch */
+#define RT8515_FLASH_MAX 16
+#define RT8515_TORCH_MAX 100
+
+#define RT8515_TIMEOUT_DEFAULT 250000U /* 250ms */
+#define RT8515_MAX_TIMEOUT_DEFAULT 300000U /* 300ms */
+
+struct rt8515 {
+ struct device *dev;
+ struct led_classdev_flash fled;
+ struct v4l2_flash *v4l2_flash;
+ struct mutex lock;
+ struct regulator *reg;
+ struct gpio_desc *enable_torch;
+ struct gpio_desc *enable_flash;
+ struct timer_list powerdown_timer;
+ u32 max_timeout; /* Flash max timeout */
+ int flash_max_intensity;
+ int torch_max_intensity;
+};
+
+static struct rt8515 *to_rt8515(struct led_classdev_flash *fled)
+{
+ return container_of(fled, struct rt8515, fled);
+}
+
+static void rt8515_gpio_brightness_commit(struct gpio_desc *gpiod,
+ int brightness)
+{
+ int i;
+
+ /*
+ * Toggling a GPIO line with a small delay increases the
+ * brightness one step at a time.
+ */
+ for (i = 0; i < brightness; i++) {
+ gpiod_set_value(gpiod, 0);
+ udelay(1);
+ gpiod_set_value(gpiod, 1);
+ udelay(1);
+ }
+}
+
+/* This is setting the torch light level */
+static int rt8515_led_brightness_set(struct led_classdev *led,
+ enum led_brightness brightness)
+{
+ struct led_classdev_flash *fled = lcdev_to_flcdev(led);
+ struct rt8515 *rt = to_rt8515(fled);
+
+ mutex_lock(&rt->lock);
+
+ if (brightness == LED_OFF) {
+ /* Off */
+ gpiod_set_value(rt->enable_flash, 0);
+ gpiod_set_value(rt->enable_torch, 0);
+ } else if (brightness < RT8515_TORCH_MAX) {
+ /* Step it up to movie mode brightness using the flash pin */
+ rt8515_gpio_brightness_commit(rt->enable_torch, brightness);
+ } else {
+ /* Max torch brightness requested */
+ gpiod_set_value(rt->enable_torch, 1);
+ }
+
+ mutex_unlock(&rt->lock);
+
+ return 0;
+}
+
+static int rt8515_led_flash_strobe_set(struct led_classdev_flash *fled,
+ bool state)
+{
+ struct rt8515 *rt = to_rt8515(fled);
+ struct led_flash_setting *timeout = &fled->timeout;
+ int brightness = rt->flash_max_intensity;
+
+ mutex_lock(&rt->lock);
+
+ if (state) {
+ /* Enable LED flash mode and set brightness */
+ rt8515_gpio_brightness_commit(rt->enable_flash, brightness);
+ /* Set timeout */
+ mod_timer(&rt->powerdown_timer,
+ jiffies + usecs_to_jiffies(timeout->val));
+ } else {
+ del_timer_sync(&rt->powerdown_timer);
+ /* Turn the LED off */
+ gpiod_set_value(rt->enable_flash, 0);
+ gpiod_set_value(rt->enable_torch, 0);
+ }
+
+ fled->led_cdev.brightness = LED_OFF;
+ /* After this the torch LED will be disabled */
+
+ mutex_unlock(&rt->lock);
+
+ return 0;
+}
+
+static int rt8515_led_flash_strobe_get(struct led_classdev_flash *fled,
+ bool *state)
+{
+ struct rt8515 *rt = to_rt8515(fled);
+
+ *state = timer_pending(&rt->powerdown_timer);
+
+ return 0;
+}
+
+static int rt8515_led_flash_timeout_set(struct led_classdev_flash *fled,
+ u32 timeout)
+{
+ /* The timeout is stored in the led-class-flash core */
+ return 0;
+}
+
+static const struct led_flash_ops rt8515_flash_ops = {
+ .strobe_set = rt8515_led_flash_strobe_set,
+ .strobe_get = rt8515_led_flash_strobe_get,
+ .timeout_set = rt8515_led_flash_timeout_set,
+};
+
+static void rt8515_powerdown_timer(struct timer_list *t)
+{
+ struct rt8515 *rt = from_timer(rt, t, powerdown_timer);
+
+ /* Turn the LED off */
+ gpiod_set_value(rt->enable_flash, 0);
+ gpiod_set_value(rt->enable_torch, 0);
+}
+
+static void rt8515_init_flash_timeout(struct rt8515 *rt)
+{
+ struct led_classdev_flash *fled = &rt->fled;
+ struct led_flash_setting *s;
+
+ /* Init flash timeout setting */
+ s = &fled->timeout;
+ s->min = 1;
+ s->max = rt->max_timeout;
+ s->step = 1;
+ /*
+ * Set default timeout to RT8515_DEFAULT_TIMEOUT except if
+ * max_timeout from DT is lower.
+ */
+ s->val = min(rt->max_timeout, RT8515_TIMEOUT_DEFAULT);
+}
+
+#if IS_ENABLED(CONFIG_V4L2_FLASH_LED_CLASS)
+/* Configure the V2L2 flash subdevice */
+static void rt8515_init_v4l2_flash_config(struct rt8515 *rt,
+ struct v4l2_flash_config *v4l2_sd_cfg)
+{
+ struct led_classdev *led = &rt->fled.led_cdev;
+ struct led_flash_setting *s;
+
+ strscpy(v4l2_sd_cfg->dev_name, led->dev->kobj.name,
+ sizeof(v4l2_sd_cfg->dev_name));
+
+ /*
+ * Init flash intensity setting: this is a linear scale
+ * capped from the device tree max intensity setting
+ * 1..flash_max_intensity
+ */
+ s = &v4l2_sd_cfg->intensity;
+ s->min = 1;
+ s->max = rt->flash_max_intensity;
+ s->step = 1;
+ s->val = s->max;
+}
+
+#else
+static void rt8515_init_v4l2_flash_config(struct rt8515 *rt,
+ struct v4l2_flash_config *v4l2_sd_cfg)
+{
+}
+#endif
+
+static void rt8515_determine_max_intensity(struct rt8515 *rt,
+ struct fwnode_handle *led,
+ const char *resistance,
+ const char *max_ua_prop, int hw_max,
+ int *max_intensity_setting)
+{
+ u32 res;
+ u32 ua;
+ u32 max_ma;
+ int max_intensity;
+ int ret1, ret2;
+
+
+ ret1 = fwnode_property_read_u32(rt->dev->fwnode, resistance, &res);
+ ret2 = fwnode_property_read_u32(led, max_ua_prop, &ua);
+
+ /* No info in DT, OK go with hardware maxima */
+ if (ret1 && ret2) {
+ max_ma = RT8515_MAX_IOUT_MA;
+ max_intensity = hw_max;
+ goto out_assign_max;
+ }
+
+ if (ret1 || ret2) {
+ dev_err(rt->dev,
+ "either %s or %s missing from DT, using HW max\n",
+ resistance, max_ua_prop);
+ max_ma = RT8515_MAX_IOUT_MA;
+ max_intensity = hw_max;
+ goto out_assign_max;
+ }
+
+ /*
+ * Formula from datasheet, this is the maximum current
+ * defined by the hardware.
+ */
+ max_ma = (5500 * 1000) / res;
+ /*
+ * Calculate max intensity (linear scaling)
+ * Formula is ((ua / 1000) / max_ma) * 100, then simplified
+ */
+ max_intensity = (ua / 10) / max_ma;
+
+ dev_info(rt->dev,
+ "current restricted from %u to %u mA, max intensity %d/100\n",
+ max_ma, (ua / 1000), max_intensity);
+
+out_assign_max:
+ dev_info(rt->dev, "max intensity %d/%d = %d mA\n",
+ max_intensity, hw_max, max_ma);
+ *max_intensity_setting = max_intensity;
+}
+
+static int rt8515_probe(struct platform_device *pdev)
+{
+ struct device *dev = &pdev->dev;
+ struct fwnode_handle *child;
+ struct rt8515 *rt;
+ struct led_classdev *led;
+ struct led_classdev_flash *fled;
+ struct led_init_data init_data = {};
+ struct v4l2_flash_config v4l2_sd_cfg = {};
+ int ret;
+
+ rt = devm_kzalloc(dev, sizeof(*rt), GFP_KERNEL);
+ if (!rt)
+ return -ENOMEM;
+
+ rt->dev = dev;
+ fled = &rt->fled;
+ led = &fled->led_cdev;
+
+ /* ENF - Enable Flash line */
+ rt->enable_flash = devm_gpiod_get(dev, "enf", GPIOD_OUT_LOW);
+ if (IS_ERR(rt->enable_flash)) {
+ dev_err(dev, "cannot get ENF (enable flash) GPIO\n");
+ return PTR_ERR(rt->enable_flash);
+ }
+
+ /* ENT - Enable Torch line */
+ rt->enable_torch = devm_gpiod_get(dev, "ent", GPIOD_OUT_LOW);
+ if (IS_ERR(rt->enable_torch)) {
+ dev_err(dev, "cannot get ENT (enable torch) GPIO\n");
+ return PTR_ERR(rt->enable_torch);
+ }
+
+ child = fwnode_get_next_available_child_node(dev->fwnode, NULL);
+ if (!child) {
+ dev_err(dev,
+ "No fwnode child node found for connected LED.\n");
+ return -EINVAL;
+ }
+ init_data.fwnode = child;
+
+ rt8515_determine_max_intensity(rt, child, "richtek,rfs-ohms",
+ "flash-max-microamp",
+ RT8515_FLASH_MAX,
+ &rt->flash_max_intensity);
+ rt8515_determine_max_intensity(rt, child, "richtek,rts-ohms",
+ "led-max-microamp",
+ RT8515_TORCH_MAX,
+ &rt->torch_max_intensity);
+
+ ret = fwnode_property_read_u32(child, "flash-max-timeout-us",
+ &rt->max_timeout);
+ if (ret) {
+ rt->max_timeout = RT8515_MAX_TIMEOUT_DEFAULT;
+ dev_warn(dev,
+ "flash-max-timeout-us property missing\n");
+ }
+ timer_setup(&rt->powerdown_timer, rt8515_powerdown_timer, 0);
+ rt8515_init_flash_timeout(rt);
+
+ fled->ops = &rt8515_flash_ops;
+
+ led->max_brightness = rt->torch_max_intensity;
+ led->brightness_set_blocking = rt8515_led_brightness_set;
+ led->flags |= LED_CORE_SUSPENDRESUME | LED_DEV_CAP_FLASH;
+
+ mutex_init(&rt->lock);
+
+ platform_set_drvdata(pdev, rt);
+
+ ret = devm_led_classdev_flash_register_ext(dev, fled, &init_data);
+ if (ret) {
+ dev_err(dev, "can't register LED %s\n", led->name);
+ mutex_destroy(&rt->lock);
+ return ret;
+ }
+
+ rt8515_init_v4l2_flash_config(rt, &v4l2_sd_cfg);
+
+ /* Create a V4L2 Flash device if V4L2 flash is enabled */
+ rt->v4l2_flash = v4l2_flash_init(dev, child, fled, NULL, &v4l2_sd_cfg);
+ if (IS_ERR(rt->v4l2_flash)) {
+ ret = PTR_ERR(rt->v4l2_flash);
+ dev_err(dev, "failed to register V4L2 flash device (%d)\n",
+ ret);
+ /*
+ * Continue without the V4L2 flash
+ * (we still have the classdev)
+ */
+ }
+
+ return 0;
+}
+
+static int rt8515_remove(struct platform_device *pdev)
+{
+ struct rt8515 *rt = platform_get_drvdata(pdev);
+
+ v4l2_flash_release(rt->v4l2_flash);
+ del_timer_sync(&rt->powerdown_timer);
+ mutex_destroy(&rt->lock);
+
+ return 0;
+}
+
+static const struct of_device_id rt8515_match[] = {
+ { .compatible = "richtek,rt8515", },
+ { /* sentinel */ },
+};
+MODULE_DEVICE_TABLE(of, rt8515_match);
+
+static struct platform_driver rt8515_driver = {
+ .driver = {
+ .name = "rt8515",
+ .of_match_table = rt8515_match,
+ },
+ .probe = rt8515_probe,
+ .remove = rt8515_remove,
+};
+module_platform_driver(rt8515_driver);
+
+MODULE_AUTHOR("Linus Walleij <linus.walleij@linaro.org>");
+MODULE_DESCRIPTION("Richtek RT8515 LED driver");
+MODULE_LICENSE("GPL v2");
--
2.26.2
^ permalink raw reply related [flat|nested] 6+ messages in thread* Re: [PATCH 1/2 v7] dt-bindings: leds: Add DT binding for Richtek RT8515
2020-12-01 10:13 [PATCH 1/2 v7] dt-bindings: leds: Add DT binding for Richtek RT8515 Linus Walleij
2020-12-01 10:13 ` [PATCH 2/2 v7] leds: rt8515: Add Richtek RT8515 LED driver Linus Walleij
@ 2020-12-09 16:31 ` Rob Herring
1 sibling, 0 replies; 6+ messages in thread
From: Rob Herring @ 2020-12-09 16:31 UTC (permalink / raw)
To: Linus Walleij
Cc: Jacek Anaszewski, Pavel Machek, Dan Murphy, linux-leds,
Sakari Ailus, newbytee, Stephan Gerhold, phone-devel,
linux-media, devicetree, Sakari Ailus
On Tue, Dec 01, 2020 at 11:13:49AM +0100, Linus Walleij wrote:
> Add a YAML devicetree binding for the Richtek RT8515
> dual channel flash/torch LED driver.
>
> Cc: Sakari Ailus <sakari.ailus@iki.fi>
> Cc: newbytee@protonmail.com
> Cc: Stephan Gerhold <stephan@gerhold.net>
> Cc: phone-devel@vger.kernel.org
> Cc: linux-media@vger.kernel.org
> Cc: devicetree@vger.kernel.org
> Reviewed-by: Sakari Ailus <sakari.ailus@linux.intel.com>
> Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
> ---
> ChangeLog v6->v7:
> - Use led-max-microamp for the torch mode max current.
> - Drop the torch-specific new property from common.yaml in
> favor of this property.
> - Collect Sakari's review tag.
> ChangeLog v5->v6:
> - Use the suffix -ohms for the resistor values as this gets
> recognized by default by dtschema and is nominal.
> ChangeLog v4->v5:
> - Fix the RFS/RTS resistors to reference the u32 schema.
> - Fix resisitor speling error.
> ChangeLog v3->v4:
> - Add DT attributes for the RFS and RTS resistors, so that
> the hardware-defined maximum current can be determined.
> - Add torch-max-microamp to the common bindings so we can
> set an attribute for the max microamp in torch mode.
> - Add flash-max-microamp and torch-max-microamp as optional
> to the LED node.
> - Slot in some elabortative descriptions of the new
> properties and describe what the hardware is doing.
> - Cc phone-devel@vger.kernel.org
> ChangeLog v2->v3:
> - Add Sakari to CC
> - Resend
> ChangeLog v1->v2:
> - Explicitly inherit function, color and flash-max-timeout-us
> from common.yaml
> - Add "led" node as required.
> ---
> .../bindings/leds/richtek,rt8515.yaml | 109 ++++++++++++++++++
> 1 file changed, 109 insertions(+)
> create mode 100644 Documentation/devicetree/bindings/leds/richtek,rt8515.yaml
>
> diff --git a/Documentation/devicetree/bindings/leds/richtek,rt8515.yaml b/Documentation/devicetree/bindings/leds/richtek,rt8515.yaml
> new file mode 100644
> index 000000000000..3190e4fcfdf2
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/leds/richtek,rt8515.yaml
> @@ -0,0 +1,109 @@
> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/leds/richtek,rt8515.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: Richtek RT8515 1.5A dual channel LED driver
> +
> +maintainers:
> + - Linus Walleij <linus.walleij@linaro.org>
> +
> +description: |
> + The Richtek RT8515 is a dual channel (two mode) LED driver that
> + supports driving a white LED in flash or torch mode. The maximum
> + current for each mode is defined in hardware using two resistors
> + RFS and RTS.
> +
> +properties:
> + compatible:
> + const: richtek,rt8515
> +
> + enf-gpios:
> + maxItems: 1
> + description: A connection to the 'ENF' (enable flash) pin.
> +
> + ent-gpios:
> + maxItems: 1
> + description: A connection to the 'ENT' (enable torch) pin.
> +
> + richtek,rfs-ohms:
> + minimum: 7680
> + maximum: 367000
> + description: The resistance value of the RFS resistor. This
> + resistors limits the maximum flash current. This must be set
> + for the property flash-max-microamp to work, the RFS resistor
> + defines the range of the dimmer setting (brightness) of the
> + flash LED.
> +
> + richtek,rts-ohms:
> + minimum: 7680
> + maximum: 367000
> + description: The resistance value of the RTS resistor. This
> + resistors limits the maximum torch current. This must be set
> + for the property torch-max-microamp to work, the RTS resistor
> + defines the range of the dimmer setting (brightness) of the
> + torch LED.
> +
> + led:
> + type: object
> + $ref: common.yaml#
additionalProperties: false
And then fix the error in the example.
With that,
Reviewed-by: Rob Herring <robh@kernel.org>
> + properties:
> + function: true
> + color: true
> + flash-max-timeout-us: true
> +
> + flash-max-microamp:
> + maximum: 700000
> + description: The maximum current for flash mode
> + is hardwired to the component using the RFS resistor to
> + ground. The maximum hardware current setting is calculated
> + according to the formula Imax = 5500 / RFS. The lowest
> + allowed resistance value is 7.86 kOhm giving an absolute
> + maximum current of 700mA. By setting this attribute in
> + the device tree, you can further restrict the maximum
> + current below the hardware limit. This requires the RFS
> + to be defined as it defines the maximum range.
> +
> + led-max-microamp:
> + maximum: 700000
> + description: The maximum current for torch mode
> + is hardwired to the component using the RTS resistor to
> + ground. The maximum hardware current setting is calculated
> + according to the formula Imax = 5500 / RTS. The lowest
> + allowed resistance value is 7.86 kOhm giving an absolute
> + maximum current of 700mA. By setting this attribute in
> + the device tree, you can further restrict the maximum
> + current below the hardware limit. This requires the RTS
> + to be defined as it defines the maximum range.
> +
> +required:
> + - compatible
> + - ent-gpios
> + - enf-gpios
> + - led
> +
> +additionalProperties: false
> +
> +examples:
> + - |
> + #include <dt-bindings/gpio/gpio.h>
> + #include <dt-bindings/leds/common.h>
> +
> + led-controller {
> + compatible = "richtek,rt8515";
> + enf-gpios = <&gpio4 12 GPIO_ACTIVE_HIGH>;
> + ent-gpios = <&gpio4 13 GPIO_ACTIVE_HIGH>;
> + richtek,rfs-ohms = <16000>;
> + richtek,rts-ohms = <100000>;
> +
> + led {
> + function = LED_FUNCTION_FLASH;
> + color = <LED_COLOR_ID_WHITE>;
> + flash-max-timeout-us = <250000>;
> + flash-max-microamp = <150000>;
> + torch-max-microamp = <25000>;
hint ^^^
> + };
> + };
> +
> +...
> --
> 2.26.2
>
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