leds: is31fl319x: 1/3/6/9-channel light effect led driver

This is a driver for the Integrated Silicon Solution Inc. LED driver
chips series IS31FL319x. They can drive 1, 3, 6  or up to 9
LEDs.

Each LED is individually controllable in brightness (through pwm)
in 256 steps so that RGB LEDs can show any of ca. 16 Mio colors.

The maximum current of the LEDs can be programmed and limited to
5 .. 40mA through a device tree property.

The chip is connected through I2C and can have one of 4 addresses
in the range 0x64 .. 0x67 depending on how the AD pin is connected. The
address is defined by the reg property as usual.

The chip also has a shutdown input which could be connected to a GPIO,
but this driver uses software shutdown if all LEDs are inactivated.

The chip also has breathing and audio features which are not fully
supported by this driver.

Tested-on: OMAP5 based Pyra handheld prototype.
Signed-off-by: H. Nikolaus Schaller <hns@goldelico.com>
Signed-off-by: Andrey Utkin <andrey_utkin@fastmail.com>
Signed-off-by: Jacek Anaszewski <j.anaszewski@samsung.com>

drivers/leds/Kconfig

@@ -584,6 +584,18 @@ config LEDS_SEAD3
 	  This driver can also be built as a module. If so the module
 	  will be called leds-sead3.
 
+config LEDS_IS31FL319X
+	tristate "LED Support for ISSI IS31FL319x I2C LED controller family"
+	depends on LEDS_CLASS && I2C && OF
+	select REGMAP_I2C
+	help
+	  This option enables support for LEDs connected to ISSI IS31FL319x
+	  fancy LED driver chips accessed via the I2C bus.
+	  Driver supports individual PWM brightness control for each channel.
+
+	  This driver can also be built as a module. If so the module will be
+	  called leds-is31fl319x.
+
 config LEDS_IS31FL32XX
 	tristate "LED support for ISSI IS31FL32XX I2C LED controller family"
 	depends on LEDS_CLASS && I2C && OF

drivers/leds/Makefile

@@ -67,6 +67,7 @@ obj-$(CONFIG_LEDS_MENF21BMC)		+= leds-menf21bmc.o
 obj-$(CONFIG_LEDS_KTD2692)		+= leds-ktd2692.o
 obj-$(CONFIG_LEDS_POWERNV)		+= leds-powernv.o
 obj-$(CONFIG_LEDS_SEAD3)		+= leds-sead3.o
+obj-$(CONFIG_LEDS_IS31FL319X)		+= leds-is31fl319x.o
 obj-$(CONFIG_LEDS_IS31FL32XX)		+= leds-is31fl32xx.o
 
 # LED SPI Drivers

drivers/leds/leds-is31fl319x.c

+/*
+ * Copyright 2015-16 Golden Delicious Computers
+ *
+ * Author: Nikolaus Schaller <hns@goldelico.com>
+ *
+ * This file is subject to the terms and conditions of version 2 of
+ * the GNU General Public License.  See the file COPYING in the main
+ * directory of this archive for more details.
+ *
+ * LED driver for the IS31FL319{0,1,3,6,9} to drive 1, 3, 6 or 9 light
+ * effect LEDs.
+ *
+ */
+
+#include <linux/err.h>
+#include <linux/i2c.h>
+#include <linux/leds.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_device.h>
+#include <linux/regmap.h>
+#include <linux/slab.h>
+
+/* register numbers */
+#define IS31FL319X_SHUTDOWN		0x00
+#define IS31FL319X_CTRL1		0x01
+#define IS31FL319X_CTRL2		0x02
+#define IS31FL319X_CONFIG1		0x03
+#define IS31FL319X_CONFIG2		0x04
+#define IS31FL319X_RAMP_MODE		0x05
+#define IS31FL319X_BREATH_MASK		0x06
+#define IS31FL319X_PWM(channel)		(0x07 + channel)
+#define IS31FL319X_DATA_UPDATE		0x10
+#define IS31FL319X_T0(channel)		(0x11 + channel)
+#define IS31FL319X_T123_1		0x1a
+#define IS31FL319X_T123_2		0x1b
+#define IS31FL319X_T123_3		0x1c
+#define IS31FL319X_T4(channel)		(0x1d + channel)
+#define IS31FL319X_TIME_UPDATE		0x26
+#define IS31FL319X_RESET		0xff
+
+#define IS31FL319X_REG_CNT		(IS31FL319X_RESET + 1)
+
+#define IS31FL319X_MAX_LEDS		9
+
+/* CS (Current Setting) in CONFIG2 register */
+#define IS31FL319X_CONFIG2_CS_SHIFT	4
+#define IS31FL319X_CONFIG2_CS_MASK	0x7
+#define IS31FL319X_CONFIG2_CS_STEP_REF	12
+
+#define IS31FL319X_CURRENT_MIN		((u32)5000)
+#define IS31FL319X_CURRENT_MAX		((u32)40000)
+#define IS31FL319X_CURRENT_STEP		((u32)5000)
+#define IS31FL319X_CURRENT_DEFAULT	((u32)20000)
+
+/* Audio gain in CONFIG2 register */
+#define IS31FL319X_AUDIO_GAIN_DB_MAX	((u32)21)
+#define IS31FL319X_AUDIO_GAIN_DB_STEP	((u32)3)
+
+/*
+ * regmap is used as a cache of chip's register space,
+ * to avoid reading back brightness values from chip,
+ * which is known to hang.
+ */
+struct is31fl319x_chip {
+	const struct is31fl319x_chipdef *cdef;
+	struct i2c_client               *client;
+	struct regmap                   *regmap;
+	struct mutex                    lock;
+	u32                             audio_gain_db;
+
+	struct is31fl319x_led {
+		struct is31fl319x_chip  *chip;
+		struct led_classdev     cdev;
+		u32                     max_microamp;
+		bool                    configured;
+	} leds[IS31FL319X_MAX_LEDS];
+};
+
+struct is31fl319x_chipdef {
+	int num_leds;
+};
+
+static const struct is31fl319x_chipdef is31fl3190_cdef = {
+	.num_leds = 1,
+};
+
+static const struct is31fl319x_chipdef is31fl3193_cdef = {
+	.num_leds = 3,
+};
+
+static const struct is31fl319x_chipdef is31fl3196_cdef = {
+	.num_leds = 6,
+};
+
+static const struct is31fl319x_chipdef is31fl3199_cdef = {
+	.num_leds = 9,
+};
+
+static const struct of_device_id of_is31fl319x_match[] = {
+	{ .compatible = "issi,is31fl3190", .data = &is31fl3190_cdef, },
+	{ .compatible = "issi,is31fl3191", .data = &is31fl3190_cdef, },
+	{ .compatible = "issi,is31fl3193", .data = &is31fl3193_cdef, },
+	{ .compatible = "issi,is31fl3196", .data = &is31fl3196_cdef, },
+	{ .compatible = "issi,is31fl3199", .data = &is31fl3199_cdef, },
+	{ .compatible = "si-en,sn3199",    .data = &is31fl3199_cdef, },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, of_is31fl319x_match);
+
+static int is31fl319x_brightness_set(struct led_classdev *cdev,
+				     enum led_brightness brightness)
+{
+	struct is31fl319x_led *led = container_of(cdev, struct is31fl319x_led,
+						  cdev);
+	struct is31fl319x_chip *is31 = led->chip;
+	int chan = led - is31->leds;
+	int ret;
+	int i;
+	u8 ctrl1 = 0, ctrl2 = 0;
+
+	dev_dbg(&is31->client->dev, "%s %d: %d\n", __func__, chan, brightness);
+
+	mutex_lock(&is31->lock);
+
+	/* update PWM register */
+	ret = regmap_write(is31->regmap, IS31FL319X_PWM(chan), brightness);
+	if (ret < 0)
+		goto out;
+
+	/* read current brightness of all PWM channels */
+	for (i = 0; i < is31->cdef->num_leds; i++) {
+		unsigned int pwm_value;
+		bool on;
+
+		/*
+		 * since neither cdev nor the chip can provide
+		 * the current setting, we read from the regmap cache
+		 */
+
+		ret = regmap_read(is31->regmap, IS31FL319X_PWM(i), &pwm_value);
+		dev_dbg(&is31->client->dev, "%s read %d: ret=%d: %d\n",
+			__func__, i, ret, pwm_value);
+		on = ret >= 0 && pwm_value > LED_OFF;
+
+		if (i < 3)
+			ctrl1 |= on << i;       /* 0..2 => bit 0..2 */
+		else if (i < 6)
+			ctrl1 |= on << (i + 1); /* 3..5 => bit 4..6 */
+		else
+			ctrl2 |= on << (i - 6); /* 6..8 => bit 0..2 */
+	}
+
+	if (ctrl1 > 0 || ctrl2 > 0) {
+		dev_dbg(&is31->client->dev, "power up %02x %02x\n",
+			ctrl1, ctrl2);
+		regmap_write(is31->regmap, IS31FL319X_CTRL1, ctrl1);
+		regmap_write(is31->regmap, IS31FL319X_CTRL2, ctrl2);
+		/* update PWMs */
+		regmap_write(is31->regmap, IS31FL319X_DATA_UPDATE, 0x00);
+		/* enable chip from shut down */
+		ret = regmap_write(is31->regmap, IS31FL319X_SHUTDOWN, 0x01);
+	} else {
+		dev_dbg(&is31->client->dev, "power down\n");
+		/* shut down (no need to clear CTRL1/2) */
+		ret = regmap_write(is31->regmap, IS31FL319X_SHUTDOWN, 0x00);
+	}
+
+out:
+	mutex_unlock(&is31->lock);
+
+	return ret;
+}
+
+static int is31fl319x_parse_child_dt(const struct device *dev,
+				     const struct device_node *child,
+				     struct is31fl319x_led *led)
+{
+	struct led_classdev *cdev = &led->cdev;
+	int ret;
+
+	if (of_property_read_string(child, "label", &cdev->name))
+		cdev->name = child->name;
+
+	ret = of_property_read_string(child, "linux,default-trigger",
+				      &cdev->default_trigger);
+	if (ret < 0 && ret != -EINVAL) /* is optional */
+		return ret;
+
+	led->max_microamp = IS31FL319X_CURRENT_DEFAULT;
+	ret = of_property_read_u32(child, "led-max-microamp",
+				   &led->max_microamp);
+	if (!ret) {
+		if (led->max_microamp < IS31FL319X_CURRENT_MIN)
+			return -EINVAL;	/* not supported */
+		led->max_microamp = min(led->max_microamp,
+					  IS31FL319X_CURRENT_MAX);
+	}
+
+	return 0;
+}
+
+static int is31fl319x_parse_dt(struct device *dev,
+			       struct is31fl319x_chip *is31)
+{
+	struct device_node *np = dev->of_node, *child;
+	const struct of_device_id *of_dev_id;
+	int count;
+	int ret;
+
+	if (!np)
+		return -ENODEV;
+
+	of_dev_id = of_match_device(of_is31fl319x_match, dev);
+	if (!of_dev_id) {
+		dev_err(dev, "Failed to match device with supported chips\n");
+		return -EINVAL;
+	}
+
+	is31->cdef = of_dev_id->data;
+
+	count = of_get_child_count(np);
+
+	dev_dbg(dev, "probe %s with %d leds defined in DT\n",
+		of_dev_id->compatible, count);
+
+	if (!count || count > is31->cdef->num_leds) {
+		dev_err(dev, "Number of leds defined must be between 1 and %u\n",
+			is31->cdef->num_leds);
+		return -ENODEV;
+	}
+
+	for_each_child_of_node(np, child) {
+		struct is31fl319x_led *led;
+		u32 reg;
+
+		ret = of_property_read_u32(child, "reg", &reg);
+		if (ret) {
+			dev_err(dev, "Failed to read led 'reg' property\n");
+			goto put_child_node;
+		}
+
+		if (reg < 1 || reg > is31->cdef->num_leds) {
+			dev_err(dev, "invalid led reg %u\n", reg);
+			ret = -EINVAL;
+			goto put_child_node;
+		}
+
+		led = &is31->leds[reg - 1];
+
+		if (led->configured) {
+			dev_err(dev, "led %u is already configured\n", reg);
+			ret = -EINVAL;
+			goto put_child_node;
+		}
+
+		ret = is31fl319x_parse_child_dt(dev, child, led);
+		if (ret) {
+			dev_err(dev, "led %u DT parsing failed\n", reg);
+			goto put_child_node;
+		}
+
+		led->configured = true;
+	}
+
+	is31->audio_gain_db = 0;
+	ret = of_property_read_u32(np, "audio-gain-db", &is31->audio_gain_db);
+	if (!ret)
+		is31->audio_gain_db = min(is31->audio_gain_db,
+					  IS31FL319X_AUDIO_GAIN_DB_MAX);
+
+	return 0;
+
+put_child_node:
+	of_node_put(child);
+	return ret;
+}
+
+static bool is31fl319x_readable_reg(struct device *dev, unsigned int reg)
+{ /* we have no readable registers */
+	return false;
+}
+
+static bool is31fl319x_volatile_reg(struct device *dev, unsigned int reg)
+{ /* volatile registers are not cached */
+	switch (reg) {
+	case IS31FL319X_DATA_UPDATE:
+	case IS31FL319X_TIME_UPDATE:
+	case IS31FL319X_RESET:
+		return true; /* always write-through */
+	default:
+		return false;
+	}
+}
+
+static const struct reg_default is31fl319x_reg_defaults[] = {
+	{ IS31FL319X_CONFIG1, 0x00},
+	{ IS31FL319X_CONFIG2, 0x00},
+	{ IS31FL319X_PWM(0), 0x00},
+	{ IS31FL319X_PWM(1), 0x00},
+	{ IS31FL319X_PWM(2), 0x00},
+	{ IS31FL319X_PWM(3), 0x00},
+	{ IS31FL319X_PWM(4), 0x00},
+	{ IS31FL319X_PWM(5), 0x00},
+	{ IS31FL319X_PWM(6), 0x00},
+	{ IS31FL319X_PWM(7), 0x00},
+	{ IS31FL319X_PWM(8), 0x00},
+};
+
+static struct regmap_config regmap_config = {
+	.reg_bits = 8,
+	.val_bits = 8,
+	.max_register = IS31FL319X_REG_CNT,
+	.cache_type = REGCACHE_FLAT,
+	.readable_reg = is31fl319x_readable_reg,
+	.volatile_reg = is31fl319x_volatile_reg,
+	.reg_defaults = is31fl319x_reg_defaults,
+	.num_reg_defaults = ARRAY_SIZE(is31fl319x_reg_defaults),
+};
+
+static inline int is31fl319x_microamp_to_cs(struct device *dev, u32 microamp)
+{ /* round down to nearest supported value (range check done by caller) */
+	u32 step = microamp / IS31FL319X_CURRENT_STEP;
+
+	return ((IS31FL319X_CONFIG2_CS_STEP_REF - step) &
+		IS31FL319X_CONFIG2_CS_MASK) <<
+		IS31FL319X_CONFIG2_CS_SHIFT; /* CS encoding */
+}
+
+static inline int is31fl319x_db_to_gain(u32 dezibel)
+{ /* round down to nearest supported value (range check done by caller) */
+	return dezibel / IS31FL319X_AUDIO_GAIN_DB_STEP;
+}
+
+static int is31fl319x_probe(struct i2c_client *client,
+			    const struct i2c_device_id *id)
+{
+	struct is31fl319x_chip *is31;
+	struct device *dev = &client->dev;
+	struct i2c_adapter *adapter = to_i2c_adapter(dev->parent);
+	int err;
+	int i = 0;
+	u32 aggregated_led_microamp = IS31FL319X_CURRENT_MAX;
+
+	if (!i2c_check_functionality(adapter, I2C_FUNC_I2C))
+		return -EIO;
+
+	is31 = devm_kzalloc(&client->dev, sizeof(*is31), GFP_KERNEL);
+	if (!is31)
+		return -ENOMEM;
+
+	mutex_init(&is31->lock);
+
+	err = is31fl319x_parse_dt(&client->dev, is31);
+	if (err)
+		goto free_mutex;
+
+	is31->client = client;
+	is31->regmap = devm_regmap_init_i2c(client, &regmap_config);
+	if (IS_ERR(is31->regmap)) {
+		dev_err(&client->dev, "failed to allocate register map\n");
+		err = PTR_ERR(is31->regmap);
+		goto free_mutex;
+	}
+
+	i2c_set_clientdata(client, is31);
+
+	/* check for write-reply from chip (we can't read any registers) */
+	err = regmap_write(is31->regmap, IS31FL319X_RESET, 0x00);
+	if (err < 0) {
+		dev_err(&client->dev, "no response from chip write: err = %d\n",
+			err);
+		err = -EIO; /* does not answer */
+		goto free_mutex;
+	}
+
+	/*
+	 * Kernel conventions require per-LED led-max-microamp property.
+	 * But the chip does not allow to limit individual LEDs.
+	 * So we take minimum from all subnodes for safety of hardware.
+	 */
+	for (i = 0; i < is31->cdef->num_leds; i++)
+		if (is31->leds[i].configured &&
+		    is31->leds[i].max_microamp < aggregated_led_microamp)
+			aggregated_led_microamp = is31->leds[i].max_microamp;
+
+	regmap_write(is31->regmap, IS31FL319X_CONFIG2,
+		     is31fl319x_microamp_to_cs(dev, aggregated_led_microamp) |
+		     is31fl319x_db_to_gain(is31->audio_gain_db));
+
+	for (i = 0; i < is31->cdef->num_leds; i++) {
+		struct is31fl319x_led *led = &is31->leds[i];
+
+		if (!led->configured)
+			continue;
+
+		led->chip = is31;
+		led->cdev.brightness_set_blocking = is31fl319x_brightness_set;
+
+		err = devm_led_classdev_register(&client->dev, &led->cdev);
+		if (err < 0)
+			goto free_mutex;
+	}
+
+	return 0;
+
+free_mutex:
+	mutex_destroy(&is31->lock);
+	return err;
+}
+
+static int is31fl319x_remove(struct i2c_client *client)
+{
+	struct is31fl319x_chip *is31 = i2c_get_clientdata(client);
+
+	mutex_destroy(&is31->lock);
+	return 0;
+}
+
+/*
+ * i2c-core (and modalias) requires that id_table be properly filled,
+ * even though it is not used for DeviceTree based instantiation.
+ */
+static const struct i2c_device_id is31fl319x_id[] = {
+	{ "is31fl3190" },
+	{ "is31fl3191" },
+	{ "is31fl3193" },
+	{ "is31fl3196" },
+	{ "is31fl3199" },
+	{ "sn3199" },
+	{},
+};
+MODULE_DEVICE_TABLE(i2c, is31fl319x_id);
+
+static struct i2c_driver is31fl319x_driver = {
+	.driver   = {
+		.name           = "leds-is31fl319x",
+		.of_match_table = of_match_ptr(of_is31fl319x_match),
+	},
+	.probe    = is31fl319x_probe,
+	.remove   = is31fl319x_remove,
+	.id_table = is31fl319x_id,
+};
+
+module_i2c_driver(is31fl319x_driver);
+
+MODULE_AUTHOR("H. Nikolaus Schaller <hns@goldelico.com>");
+MODULE_AUTHOR("Andrey Utkin <andrey_utkin@fastmail.com>");
+MODULE_DESCRIPTION("IS31FL319X LED driver");
+MODULE_LICENSE("GPL v2");