Re: [PATCH v9 09/10] leds: flash: mt6370: Add MediaTek MT6370 flashlight support

From: Alice Chen <redacted>

The MediaTek MT6370 is a highly-integrated smart power management IC,
which includes a single cell Li-Ion/Li-Polymer switching battery
charger, a USB Type-C & Power Delivery (PD) controller, dual Flash
LED current sources, a RGB LED driver, a backlight WLED driver,
a display bias driver and a general LDO for portable devices.

Add support for the MT6370 Flash LED driver. Flash LED in MT6370
has 2 channels and support torch/strobe mode.

Signed-off-by: Alice Chen <redacted>
Signed-off-by: ChiaEn Wu <redacted>
---

v9
- Revise the format of the comments.
---
  drivers/leds/flash/Kconfig             |  14 +
  drivers/leds/flash/Makefile            |   1 +
  drivers/leds/flash/leds-mt6370-flash.c | 632 +++++++++++++++++++++++++++++++++
  3 files changed, 647 insertions(+)
  create mode 100644 drivers/leds/flash/leds-mt6370-flash.c

diff --git a/drivers/leds/flash/Kconfig b/drivers/leds/flash/Kconfig
index d3eb689..405bd16 100644
--- a/drivers/leds/flash/Kconfig
+++ b/drivers/leds/flash/Kconfig

@@ -61,6 +61,20 @@ config LEDS_MT6360
  	  Independent current sources supply for each flash LED support torch
  	  and strobe mode.
  
+config LEDS_MT6370_FLASH
+	tristate "Flash LED Support for MediaTek MT6370 PMIC"
+	depends on LEDS_CLASS && OF
+	depends on LEDS_CLASS_FLASH || !LEDS_CLASS_FLASH
+	depends on V4L2_FLASH_LED_CLASS || !V4L2_FLASH_LED_CLASS
+	depends on MFD_MT6370
+	help
+	  Support 2 channels and torch/strobe mode.
+	  Say Y here to enable support for
+	  MT6370_FLASH_LED device.
+
+	  This driver can also be built as a module. If so, the module
+	  will be called "leds-mt6370-flash".
+
  config LEDS_RT4505
  	tristate "LED support for RT4505 flashlight controller"
  	depends on I2C && OF

diff --git a/drivers/leds/flash/Makefile b/drivers/leds/flash/Makefile
index 0acbddc..0c1f3c5 100644
--- a/drivers/leds/flash/Makefile
+++ b/drivers/leds/flash/Makefile

@@ -9,3 +9,4 @@ obj-$(CONFIG_LEDS_MAX77693)	+= leds-max77693.o
  obj-$(CONFIG_LEDS_RT4505)	+= leds-rt4505.o
  obj-$(CONFIG_LEDS_RT8515)	+= leds-rt8515.o
  obj-$(CONFIG_LEDS_SGM3140)	+= leds-sgm3140.o
+obj-$(CONFIG_LEDS_MT6370_FLASH)	+= leds-mt6370-flash.o

diff --git a/drivers/leds/flash/leds-mt6370-flash.c b/drivers/leds/flash/leds-mt6370-flash.c
new file mode 100644
index 0000000..a8ec7e1
--- /dev/null
+++ b/drivers/leds/flash/leds-mt6370-flash.c

@@ -0,0 +1,632 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2022 Richtek Technology Corp.
+ *
+ * Author: Alice Chen <alice_chen@richtek.com>
+ */
+
+#include <linux/bitops.h>
+#include <linux/delay.h>
+#include <linux/init.h>
+#include <linux/interrupt.h>
+#include <linux/kernel.h>
+#include <linux/led-class-flash.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/platform_device.h>
+#include <linux/property.h>
+#include <linux/regmap.h>
+
+#include <media/v4l2-flash-led-class.h>
+
+enum {
+	MT6370_LED_FLASH1,
+	MT6370_LED_FLASH2,
+	MT6370_MAX_LEDS
+};
+
+/* Virtual definition for multicolor */
+
+#define MT6370_REG_FLEDEN		0x17E
+#define MT6370_REG_STRBTO		0x173
+#define MT6370_REG_CHGSTAT2		0x1D1
+#define MT6370_REG_FLEDSTAT1		0x1D9
+#define MT6370_REG_FLEDISTRB(_id)	(0x174 + 4 * (_id))
+#define MT6370_REG_FLEDITOR(_id)	(0x175 + 4 * (_id))
+#define MT6370_ITORCH_MASK		GENMASK(4, 0)
+#define MT6370_ISTROBE_MASK		GENMASK(6, 0)
+#define MT6370_STRBTO_MASK		GENMASK(6, 0)
+#define MT6370_TORCHEN_MASK		BIT(3)
+#define MT6370_STROBEN_MASK		BIT(2)
+#define MT6370_FLCSEN_MASK(_id)		BIT(MT6370_LED_FLASH2 - (_id))
+#define MT6370_FLCSEN_MASK_ALL		GENMASK(1, 0)
+#define MT6370_FLEDCHGVINOVP_MASK	BIT(3)
+#define MT6370_FLED1STRBTO_MASK		BIT(11)
+#define MT6370_FLED2STRBTO_MASK		BIT(10)
+#define MT6370_FLED1STRB_MASK		BIT(9)
+#define MT6370_FLED2STRB_MASK		BIT(8)
+#define MT6370_FLED1SHORT_MASK		BIT(7)
+#define MT6370_FLED2SHORT_MASK		BIT(6)
+#define MT6370_FLEDLVF_MASK		BIT(3)
+
+#define MT6370_LED_JOINT		2
+#define MT6370_RANGE_FLED_REG		4
+#define MT6370_ITORCH_MIN_uA		25000
+#define MT6370_ITORCH_STEP_uA		12500
+#define MT6370_ITORCH_MAX_uA		400000
+#define MT6370_ITORCH_DOUBLE_MAX_uA	800000
+#define MT6370_ISTRB_MIN_uA		50000
+#define MT6370_ISTRB_STEP_uA		12500
+#define MT6370_ISTRB_MAX_uA		1500000
+#define MT6370_ISTRB_DOUBLE_MAX_uA	3000000
+#define MT6370_STRBTO_MIN_US		64000
+#define MT6370_STRBTO_STEP_US		32000
+#define MT6370_STRBTO_MAX_US		2432000
+
+#define STATE_OFF			0
+#define STATE_KEEP			1
+#define STATE_ON			2
+
+#define to_mt6370_led(ptr, member) container_of(ptr, struct mt6370_led, member)
+
+struct mt6370_led {
+	struct led_classdev_flash flash;
+	struct v4l2_flash *v4l2_flash;
+	struct mt6370_priv *priv;
+	u32 led_no;

+};
+
+struct mt6370_priv {
+	struct device *dev;
+	struct regmap *regmap;
+	struct mutex lock;
+	unsigned int fled_strobe_used;
+	unsigned int fled_torch_used;
+	unsigned int leds_active;
+	unsigned int leds_count;
+	struct mt6370_led leds[];
+};
+
+static int mt6370_torch_brightness_set(struct led_classdev *lcdev,
+				       enum led_brightness level)
+{
+	struct mt6370_led *led = to_mt6370_led(lcdev, flash.led_cdev);
+	struct mt6370_priv *priv = led->priv;
+	u32 led_enable_mask = (led->led_no == MT6370_LED_JOINT) ?
+			      MT6370_FLCSEN_MASK_ALL :
+			      MT6370_FLCSEN_MASK(led->led_no);
+	u32 enable_mask = MT6370_TORCHEN_MASK | led_enable_mask;
+	u32 val = level ? led_enable_mask : 0;
+	u32 curr;
+	int ret, i;
+
+	mutex_lock(&priv->lock);
+
+	/*
+	 * There is only one set of flash control logic, and this
+	 * flag is used to check if 'strobe' is currently being used.
+	 */
+	if (priv->fled_strobe_used) {
+		dev_warn(lcdev->dev, "Please disable strobe first [%d]\n",
+			 priv->fled_strobe_used);
+		ret = -EBUSY;
+		goto unlock;
+	}
+
+	if (level)
+		curr = priv->fled_torch_used | BIT(led->led_no);
+	else
+		curr = priv->fled_torch_used & ~BIT(led->led_no);
+
+	if (curr)
+		val |= MT6370_TORCHEN_MASK;
+
+	if (level) {
+		level -= 1;
+		if (led->led_no == MT6370_LED_JOINT) {
+			int flevel[MT6370_MAX_LEDS];
+
+			flevel[0] = level / 2;
+			flevel[1] = level - flevel[0];
+			for (i = 0; i < MT6370_MAX_LEDS; i++) {
+				ret = regmap_update_bits(priv->regmap,
+						MT6370_REG_FLEDITOR(i),
+						MT6370_ITORCH_MASK, flevel[i]);
+				if (ret)
+					goto unlock;
+			}
+		} else {
+			ret = regmap_update_bits(priv->regmap,
+					MT6370_REG_FLEDITOR(led->led_no),
+					MT6370_ITORCH_MASK, level);
+			if (ret)
+				goto unlock;
+		}
+	}
+
+	ret = regmap_update_bits(priv->regmap, MT6370_REG_FLEDEN,
+				 enable_mask, val);
+	if (ret)
+		goto unlock;
+
+	priv->fled_torch_used = curr;
+
+unlock:
+	mutex_unlock(&priv->lock);
+	return ret;
+}
+
+static int mt6370_flash_brightness_set(struct led_classdev_flash *fl_cdev,
+				       u32 brightness)
+{
+	/*
+	 * Because of the current spikes when turning on the flash,
+	 * the brightness should be kept by the LED framework. This
+	 * empty function is used to prevent checking failure when
+	 * led_classdev_flash registers ops.
+	 */
+	return 0;
+}
+
+static int _mt6370_flash_brightness_set(struct led_classdev_flash *fl_cdev,
+					u32 brightness)
+{
+	struct mt6370_led *led = to_mt6370_led(fl_cdev, flash);
+	struct mt6370_priv *priv = led->priv;
+	struct led_flash_setting *s = &fl_cdev->brightness;
+	u32 val = (brightness - s->min) / s->step;
+	int ret, i;
+
+	if (led->led_no == MT6370_LED_JOINT) {
+		int flevel[MT6370_MAX_LEDS];

+
+		flevel[0] = val / 2;
+		flevel[1] = val - flevel[0];
+		for (i = 0; i < MT6370_MAX_LEDS; i++) {
+			ret = regmap_update_bits(priv->regmap,
+						 MT6370_REG_FLEDISTRB(i),
+						 MT6370_ISTROBE_MASK, flevel[i]);
+			if (ret)
+				return ret;
+		}
+	} else {
+		return regmap_update_bits(priv->regmap,
+					  MT6370_REG_FLEDISTRB(led->led_no),
+					  MT6370_ISTROBE_MASK, val);
+	}
+
+	return 0;

+}
+
+static int mt6370_strobe_set(struct led_classdev_flash *fl_cdev, bool state)
+{
+	struct mt6370_led *led = to_mt6370_led(fl_cdev, flash);
+	struct mt6370_priv *priv = led->priv;
+	struct led_classdev *lcdev = &fl_cdev->led_cdev;
+	struct led_flash_setting *s = &fl_cdev->brightness;
+	u32 led_enable_mask = (led->led_no == MT6370_LED_JOINT) ?
+			      MT6370_FLCSEN_MASK_ALL :
+			      MT6370_FLCSEN_MASK(led->led_no);
+	u32 enable_mask = MT6370_STROBEN_MASK | led_enable_mask;
+	u32 val = state ? led_enable_mask : 0;
+	u32 curr;
+	int ret;
+
+	mutex_lock(&priv->lock);
+
+	/*
+	 * There is only one set of flash control logic, and this
+	 * flag is used to check if 'torch' is currently being used.
+	 */
+	if (priv->fled_torch_used) {
+		dev_warn(lcdev->dev, "Please disable torch first [0x%x]\n",
+				      priv->fled_torch_used);
+		ret = -EBUSY;
+		goto unlock;
+	}
+
+	if (state)
+		curr = priv->fled_strobe_used | BIT(led->led_no);
+	else
+		curr = priv->fled_strobe_used & ~BIT(led->led_no);
+
+	if (curr)
+		val |= MT6370_STROBEN_MASK;
+
+	ret = regmap_update_bits(priv->regmap, MT6370_REG_FLEDEN, enable_mask,
+				 val);
+	if (ret) {
+		dev_err(lcdev->dev, "[%d] control current source %d fail\n",
+				     led->led_no, state);
+		goto unlock;
+	}
+
+	/*
+	 * If the flash needs to turn on, configure the flash current to
+	 * ramp up to the setting value. Otherwise, always revert to the
+	 * minimum one.
+	 */
+	ret = _mt6370_flash_brightness_set(fl_cdev, state ? s->val : s->min);
+	if (ret)
+		goto unlock;

+
+	/*
+	 * For the flash to turn on/off, we must wait for HW ramping
+	 * up/down time 5ms/500us to prevent the unexpected problem.
+	 */
+	if (!priv->fled_strobe_used && curr)
+		usleep_range(5000, 6000);
+	else if (priv->fled_strobe_used && !curr)
+		usleep_range(500, 600);
+
+	priv->fled_strobe_used = curr;
+
+unlock:
+	mutex_unlock(&priv->lock);
+	return ret;
+}
+

+
+static int mt6370_init_common_properties(struct mt6370_led *led,
+					 struct led_init_data *init_data)
+{
+	const char * const states[] = { "off", "keep", "on" };
+	const char *str = states[STATE_OFF];
+	int ret;
+
+	fwnode_property_read_string(init_data->fwnode, "default-state", &str);
+	ret = match_string(states, ARRAY_SIZE(states), str);
+	if (ret >= 0)
+		led->default_state = ret;
+
+	return 0;
+}
+
+static int mt6370_led_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct mt6370_priv *priv;
+	struct fwnode_handle *child;
+	size_t count;
+	int i = 0, ret;
+
+	count = device_get_child_node_count(dev);
+	if (!count || count > MT6370_MAX_LEDS)
+		return dev_err_probe(dev, -EINVAL,
+		       "No child node or node count over max led number %zu\n", count);
+
+	priv = devm_kzalloc(dev, struct_size(priv, leds, count), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+
+	priv->leds_count = count;
+	priv->dev = dev;
+	mutex_init(&priv->lock);
+
+	priv->regmap = dev_get_regmap(dev->parent, NULL);
+	if (!priv->regmap)
+		return dev_err_probe(dev, -ENODEV, "Failed to get parent regmap\n");
+
+	device_for_each_child_node(dev, child) {
+		struct mt6370_led *led = priv->leds + i;
+		struct led_init_data init_data = { .fwnode = child, };
+
+		led->priv = priv;
+		ret = mt6370_init_common_properties(led, &init_data);

+		if (ret)
+			return ret;
+
+		ret = mt6370_init_flash_properties(led, &init_data);
+		if (ret)
+			return ret;
+
+		ret = mt6370_led_register(dev, led, &init_data);
+		if (ret)
+			return ret;
+
+		i++;
+	}
+
+	return 0;
+}
+