diff mbox series

[2/2,v7] leds: rt8515: Add Richtek RT8515 LED driver

Message ID 20201201101350.1401956-2-linus.walleij@linaro.org
State Superseded
Headers show
Series [1/2,v7] dt-bindings: leds: Add DT binding for Richtek RT8515 | expand

Commit Message

Linus Walleij Dec. 1, 2020, 10:13 a.m. UTC
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

Comments

Pavel Machek Dec. 30, 2020, 7:09 p.m. UTC | #1
Hi!

> 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.


Please move this to the comment in the sources... perhaps with url for
the documenation.

> +/* 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);


Do you need to somehow reset the LED to lowest brightness before
rt8515_gpio_brightness_commit()?

> +	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;

> +	}


I'd go with some minimum values if we don't have complete information
from devicetree.

> +	/* 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);


Is it cool to call v4l2_flash_release() with error pointer?

> +MODULE_LICENSE("GPL v2");


v2+, iirc?

Driver looks good, thanks!
								Pavel

-- 
http://www.livejournal.com/~pavelmachek
Linus Walleij Jan. 1, 2021, 2:19 p.m. UTC | #2
Hi Pavel,

will send a new version with some minor tweaks!

On Wed, Dec 30, 2020 at 8:09 PM Pavel Machek <pavel@ucw.cz> wrote:

> > +     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;
> > +     }
>
> I'd go with some minimum values if we don't have complete information
> from devicetree.

I think this is safe because of the way the current limiting
resistors work, the device is designed to have hardware
constraints on currents. The max brightness is the max
current as limited by hardware. It is not possible to break
this LED with software.

Of course someone could have mounted the LED in violation
of the manual but ... we can't protect for everything I think.

The resistances etc is mainly here to give v4l an idea of the
current since V4L is a current-oriented API. Not a good fit
in this case, but with these DT properties we can make it fit
somewhat so ... ¯\_(ツ)_/¯

> > +MODULE_LICENSE("GPL v2");
>
> v2+, iirc?

It seems GPL-2.0-or-late just use "GPL" as license so I changed
to that.

Yours,
Linus Walleij
diff mbox series

Patch

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");