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leds: rt8515: Add Richtek RT8515 LED driver

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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.

Sakari Ailus, Pavel Machek and Andy Shevchenko helped
significantly in getting this driver right.

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>
Signed-off-by: Pavel Machek <pavel@ucw.cz>
This commit is contained in:
Linus Walleij 2021-01-03 00:15:10 +01:00 committed by Pavel Machek
parent c8283eb79d
commit e1c6edcbea
5 changed files with 421 additions and 0 deletions
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3
drivers/leds/Kconfig
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@ -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"

3
drivers/leds/Makefile
View File

@ -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/

15
drivers/leds/flash/Kconfig Normal file
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@ -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

3
drivers/leds/flash/Makefile Normal file
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@ -0,0 +1,3 @@
# SPDX-License-Identifier: GPL-2.0
obj-$(CONFIG_LEDS_RT8515) += leds-rt8515.o

397
drivers/leds/flash/leds-rt8515.c Normal file
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@ -0,0 +1,397 @@
// 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.
*
* The component lacks a datasheet, but in the schematic picture
* from the LG P970 service manual you can see the connections
* from the RT8515 to the LED, with two resistors connected
* from the pins "RFS" and "RTS" to ground.
*
* On the LG P970:
* RFS (resistance flash setting?) is 20 kOhm
* RTS (resistance torch setting?) is 39 kOhm
*
* Some sleuthing finds us the RT9387A which we have a datasheet for:
* https://static5.arrow.com/pdfs/2014/7/27/8/21/12/794/rtt_/manual/94download_ds.jspprt9387a.jspprt9387a.pdf
* This apparently works the same way so in theory this driver
* should cover RT9387A as well. This has not been tested, please
* update the compatibles if you add RT9387A support.
*
* 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/mod_devicetable.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/property.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_US 250000U
#define RT8515_MAX_TIMEOUT_US 300000U
struct rt8515 {
struct led_classdev_flash fled;
struct device *dev;
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_led_off(struct rt8515 *rt)
{
gpiod_set_value(rt->enable_flash, 0);
gpiod_set_value(rt->enable_torch, 0);
}
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 */
rt8515_gpio_led_off(rt);
} 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 */
rt8515_gpio_led_off(rt);
}
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 */
rt8515_gpio_led_off(rt);
}
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_TIMEOUT_US except if
* max_timeout from DT is lower.
*/
s->val = min(rt->max_timeout, RT8515_TIMEOUT_US);
}
#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;
}
static void rt8515_v4l2_flash_release(struct rt8515 *rt)
{
v4l2_flash_release(rt->v4l2_flash);
}
#else
static void rt8515_init_v4l2_flash_config(struct rt8515 *rt,
struct v4l2_flash_config *v4l2_sd_cfg)
{
}
static void rt8515_v4l2_flash_release(struct rt8515 *rt)
{
}
#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 = 0; /* Can't be 0 so 0 is undefined */
u32 ua;
u32 max_ma;
int max_intensity;
int ret;
fwnode_property_read_u32(rt->dev->fwnode, resistance, &res);
ret = fwnode_property_read_u32(led, max_ua_prop, &ua);
/* Missing info in DT, OK go with hardware maxima */
if (ret || res == 0) {
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 the 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))
return dev_err_probe(dev, PTR_ERR(rt->enable_flash),
"cannot get ENF (enable flash) GPIO\n");
/* ENT - Enable Torch line */
rt->enable_torch = devm_gpiod_get(dev, "ent", GPIOD_OUT_LOW);
if (IS_ERR(rt->enable_torch))
return dev_err_probe(dev, PTR_ERR(rt->enable_torch),
"cannot get ENT (enable torch) GPIO\n");
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_US;
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);
rt8515_v4l2_flash_release(rt);
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");