[PATCH 1/2] backlight: arcxcnn: add support for ArticSand devices

[PATCH 1/2] backlight: arcxcnn: add support for ArticSand devices

[Olimpiu Dejeu]

Re-submission of arcxcnn backlight driver addressing the naming convention
 concerns raised by Rob H.

Signed-off-by: Olimpiu Dejeu <olimpiu@arcticsand.com>

---
 drivers/video/backlight/Kconfig      |   7 +
 drivers/video/backlight/Makefile     |   1 +
 drivers/video/backlight/arcxcnn_bl.c | 541 +++++++++++++++++++++++++++++++++++
 include/linux/i2c/arcxcnn.h          |  67 +++++
 4 files changed, 616 insertions(+)
 create mode 100644 drivers/video/backlight/arcxcnn_bl.c
 create mode 100644 include/linux/i2c/arcxcnn.h

diff --git a/drivers/video/backlight/Kconfig b/drivers/video/backlight/Kconfig
index 5ffa4b4..4e1d2ad 100644
--- a/drivers/video/backlight/Kconfig
+++ b/drivers/video/backlight/Kconfig
@@ -460,6 +460,13 @@ config BACKLIGHT_BD6107
 	help
 	  If you have a Rohm BD6107 say Y to enable the backlight driver.
 
+config BACKLIGHT_ARCXCNN
+	tristate "Backlight driver for the Arctic Sands ARCxCnnnn family"
+	depends on I2C
+	help
+	  If you have an ARCxCnnnn family backlight say Y to enable
+	  the backlight driver.
+
 endif # BACKLIGHT_CLASS_DEVICE
 
 endif # BACKLIGHT_LCD_SUPPORT
diff --git a/drivers/video/backlight/Makefile b/drivers/video/backlight/Makefile
index 16ec534..8905129 100644
--- a/drivers/video/backlight/Makefile
+++ b/drivers/video/backlight/Makefile
@@ -55,3 +55,4 @@ obj-$(CONFIG_BACKLIGHT_SKY81452)	+= sky81452-backlight.o
 obj-$(CONFIG_BACKLIGHT_TOSA)		+= tosa_bl.o
 obj-$(CONFIG_BACKLIGHT_TPS65217)	+= tps65217_bl.o
 obj-$(CONFIG_BACKLIGHT_WM831X)		+= wm831x_bl.o
+obj-$(CONFIG_BACKLIGHT_ARCXCNN) 	+= arcxcnn_bl.o
diff --git a/drivers/video/backlight/arcxcnn_bl.c b/drivers/video/backlight/arcxcnn_bl.c
new file mode 100644
index 0000000..1dad680
--- /dev/null
+++ b/drivers/video/backlight/arcxcnn_bl.c
@@ -0,0 +1,541 @@
+/*
+ * Backlight driver for ArcticSand ARC_X_C_0N_0N Devices
+ *
+ * Copyright 2016 ArcticSand, Inc.
+ *
+ * Licensed under the GPL-2 or later.
+ */
+
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/i2c.h>
+#include <linux/backlight.h>
+#include <linux/err.h>
+#include <linux/of.h>
+#include <linux/pwm.h>
+#include <linux/regulator/consumer.h>
+
+#include "linux/i2c/arcxcnn.h"
+
+#define ARCXCNN_CMD		(0x00)  /* Command Register */
+#define ARCXCNN_CMD_STDBY	(0x80)	/* I2C Standby */
+#define ARCXCNN_CMD_RESET	(0x40)	/* Reset */
+#define ARCXCNN_CMD_BOOST	(0x10)	/* Boost */
+#define ARCXCNN_CMD_OVP_MASK	(0x0C)	/* --- Over Voltage Threshold */
+#define ARCXCNN_CMD_OVP_XXV	(0x0C)	/* <rsvrd> Over Voltage Threshold */
+#define ARCXCNN_CMD_OVP_20V	(0x08)	/* 20v Over Voltage Threshold */
+#define ARCXCNN_CMD_OVP_24V	(0x04)	/* 24v Over Voltage Threshold */
+#define ARCXCNN_CMD_OVP_31V	(0x00)	/* 31.4v Over Voltage Threshold */
+#define ARCXCNN_CMD_EXT_COMP	(0x01)	/* part (0) or full (1) external comp */
+
+#define ARCXCNN_CONFIG	(0x01)  /* Configuration */
+#define ARCXCNN_STATUS1	(0x02)  /* Status 1 */
+#define ARCXCNN_STATUS2	(0x03)  /* Status 2 */
+#define ARCXCNN_FADECTRL	(0x04)  /* Fading Control */
+#define ARCXCNN_ILED_CONFIG	(0x05)  /* ILED Configuration */
+
+#define ARCXCNN_LEDEN		(0x06)  /* LED Enable Register */
+#define ARCXCNN_LEDEN_ISETEXT	(0x80)	/* Full-scale current set externally */
+#define ARCXCNN_LEDEN_MASK	(0x3F)	/* LED string enables */
+#define ARCXCNN_LEDEN_LED1	(0x01)
+#define ARCXCNN_LEDEN_LED2	(0x02)
+#define ARCXCNN_LEDEN_LED3	(0x04)
+#define ARCXCNN_LEDEN_LED4	(0x08)
+#define ARCXCNN_LEDEN_LED5	(0x10)
+#define ARCXCNN_LEDEN_LED6	(0x20)
+
+#define ARCXCNN_WLED_ISET_LSB	(0x07)  /* LED ISET LSB (in upper nibble) */
+#define ARCXCNN_WLED_ISET_MSB	(0x08)  /* LED ISET MSB (8 bits) */
+
+#define ARCXCNN_DIMFREQ		(0x09)
+#define ARCXCNN_COMP_CONFIG	(0x0A)
+#define ARCXCNN_FILT_CONFIG	(0x0B)
+#define ARCXCNN_IMAXTUNE	(0x0C)
+
+#define DEFAULT_BL_NAME		"arctic_bl"
+#define MAX_BRIGHTNESS		4095
+
+static int s_no_reset_on_remove;
+module_param_named(noreset, s_no_reset_on_remove, int, 0644);
+MODULE_PARM_DESC(noreset, "No reset on module removal");
+
+static int s_ibright = 60;
+module_param_named(ibright, s_ibright, int, 0644);
+MODULE_PARM_DESC(ibright, "Initial brightness (when no plat data)");
+
+static int s_iledstr = 0x3F;
+module_param_named(iledstr, s_iledstr, int, 0644);
+MODULE_PARM_DESC(iledstr, "Initial LED String (when no plat data)");
+
+static int s_retries = 2; /* 1 == only one try */
+module_param_named(retries, s_retries, int, 0644);
+MODULE_PARM_DESC(retries, "I2C retries attempted");
+
+enum arcxcnn_brightness_ctrl_mode {
+	PWM_BASED = 1,
+	REGISTER_BASED,
+};
+
+struct arcxcnn;
+
+struct arcxcnn {
+	char chipname[64];
+	enum arcxcnn_chip_id chip_id;
+	enum arcxcnn_brightness_ctrl_mode mode;
+	struct i2c_client *client;
+	struct backlight_device *bl;
+	struct device *dev;
+	struct arcxcnn_platform_data *pdata;
+	struct pwm_device *pwm;
+	struct regulator *supply;	/* regulator for VDD input */
+};
+
+static int arcxcnn_write_byte(struct arcxcnn *lp, u8 reg, u8 data)
+{
+	s32 ret = -1;
+	int att;
+
+	for (att = 0; att < s_retries; att++) {
+		ret = i2c_smbus_write_byte_data(lp->client, reg, data);
+		if (ret >= 0)
+			return 0;
+	}
+	return ret;
+}
+
+static u8 arcxcnn_read_byte(struct arcxcnn *lp, u8 reg)
+{
+	int val;
+	int att;
+
+	for (att = 0; att < s_retries; att++) {
+		val = i2c_smbus_read_byte_data(lp->client, reg);
+		if (val >= 0)
+			return (u8)val;
+	}
+	return 0;
+}
+
+static int arcxcnn_update_bit(struct arcxcnn *lp, u8 reg, u8 mask, u8 data)
+{
+	int ret, att;
+	u8 tmp;
+
+	for (att = 0, ret = -1; att < s_retries; att++) {
+		ret = i2c_smbus_read_byte_data(lp->client, reg);
+		if (ret >= 0)
+			break;
+	}
+	if (ret < 0) {
+		dev_err(lp->dev, "failed to read 0x%.2x\n", reg);
+		return ret;
+	}
+
+	tmp = (u8)ret;
+	tmp &= ~mask;
+	tmp |= data & mask;
+
+	return arcxcnn_write_byte(lp, reg, tmp);
+}
+
+static int arcxcnn_set_brightness(struct arcxcnn *lp, u32 brightness)
+{
+	int ret;
+	u8 val;
+
+	val = (brightness & 0xF) << 4;
+	ret = arcxcnn_write_byte(lp, ARCXCNN_WLED_ISET_LSB, val);
+	if (ret < 0)
+		return ret;
+	val = (brightness >> 4);
+	ret = arcxcnn_write_byte(lp, ARCXCNN_WLED_ISET_MSB, val);
+	return ret;
+}
+
+static int arcxcnn_bl_update_status(struct backlight_device *bl)
+{
+	struct arcxcnn *lp = bl_get_data(bl);
+	u32 brightness = bl->props.brightness;
+
+	if (bl->props.state & (BL_CORE_SUSPENDED | BL_CORE_FBBLANK))
+		brightness = 0;
+
+	/* set brightness */
+	if (lp->mode == PWM_BASED)
+		; /* via pwm */
+	else if (lp->mode == REGISTER_BASED)
+		arcxcnn_set_brightness(lp, brightness);
+
+	/* set power-on/off/save modes */
+	if (bl->props.power == 0)
+		/* take out of standby */
+		arcxcnn_update_bit(lp, ARCXCNN_CMD, ARCXCNN_CMD_STDBY, 0);
+	else
+		/* 1-3 == power save, 4 = off
+		 * place in low-power standby mode
+		 */
+		arcxcnn_update_bit(lp, ARCXCNN_CMD,
+				ARCXCNN_CMD_STDBY, ARCXCNN_CMD_STDBY);
+	return 0;
+}
+
+static const struct backlight_ops arcxcnn_bl_ops = {
+	.options = BL_CORE_SUSPENDRESUME,
+	.update_status = arcxcnn_bl_update_status,
+};
+
+static int arcxcnn_backlight_register(struct arcxcnn *lp)
+{
+	struct backlight_device *bl;
+	struct backlight_properties props;
+	struct arcxcnn_platform_data *pdata = lp->pdata;
+	const char *name = pdata->name ? : DEFAULT_BL_NAME;
+
+	memset(&props, 0, sizeof(props));
+	props.type = BACKLIGHT_PLATFORM;
+	props.max_brightness = MAX_BRIGHTNESS;
+
+	if (pdata->initial_brightness > props.max_brightness)
+		pdata->initial_brightness = props.max_brightness;
+
+	props.brightness = pdata->initial_brightness;
+
+	bl = devm_backlight_device_register(lp->dev, name, lp->dev, lp,
+				       &arcxcnn_bl_ops, &props);
+	if (IS_ERR(bl))
+		return PTR_ERR(bl);
+
+	lp->bl = bl;
+
+	return 0;
+}
+
+static ssize_t arcxcnn_get_chip_id(struct device *dev,
+		struct device_attribute *attr, char *buf)
+{
+	struct arcxcnn *lp = dev_get_drvdata(dev);
+
+	return scnprintf(buf, PAGE_SIZE, "%s\n", lp->chipname);
+}
+
+static ssize_t arcxcnn_get_led_str(struct device *dev,
+		struct device_attribute *attr, char *buf)
+{
+	struct arcxcnn *lp = dev_get_drvdata(dev);
+
+	return scnprintf(buf, PAGE_SIZE, "%02X\n", lp->pdata->led_str);
+}
+
+static ssize_t arcxcnn_set_led_str(struct device *dev,
+		struct device_attribute *attr, const char *buf, size_t len)
+{
+	struct arcxcnn *lp = dev_get_drvdata(dev);
+	unsigned long ledstr;
+
+	if (kstrtoul(buf, 0, &ledstr))
+		return 0;
+
+	if (ledstr != lp->pdata->led_str) {
+		/* don't allow 0 for ledstr, use power to turn all off */
+		if (ledstr == 0)
+			return 0;
+		lp->pdata->led_str = ledstr & 0x3F;
+		arcxcnn_update_bit(lp, ARCXCNN_LEDEN,
+			ARCXCNN_LEDEN_MASK, lp->pdata->led_str);
+	}
+	return len;
+}
+
+static ssize_t arcxcnn_get_bl_ctl_mode(struct device *dev,
+	     struct device_attribute *attr, char *buf)
+{
+	struct arcxcnn *lp = dev_get_drvdata(dev);
+	char *strmode = NULL;
+
+	if (lp->mode == PWM_BASED)
+		strmode = "pwm based";
+	else if (lp->mode == REGISTER_BASED)
+		strmode = "register based";
+
+	return scnprintf(buf, PAGE_SIZE, "%s\n", strmode);
+}
+
+static DEVICE_ATTR(chip_id, 0444, arcxcnn_get_chip_id, NULL);
+static DEVICE_ATTR(led_str, 0664, arcxcnn_get_led_str, arcxcnn_set_led_str);
+static DEVICE_ATTR(bl_ctl_mode, 0444, arcxcnn_get_bl_ctl_mode, NULL);
+
+static struct attribute *arcxcnn_attributes[] = {
+	&dev_attr_chip_id.attr,
+	&dev_attr_led_str.attr,
+	&dev_attr_bl_ctl_mode.attr,
+	NULL,
+};
+
+static const struct attribute_group arcxcnn_attr_group = {
+	.attrs = arcxcnn_attributes,
+};
+
+#ifdef CONFIG_OF
+static int arcxcnn_parse_dt(struct arcxcnn *lp)
+{
+	struct device *dev = lp->dev;
+	struct device_node *node = dev->of_node;
+	u32 prog_val, num_entry, sources[6];
+	int ret;
+
+	if (!node) {
+		dev_err(dev, "no platform data.\n");
+		return -EINVAL;
+	}
+	lp->pdata->led_config_0_set = false;
+	lp->pdata->led_config_1_set = false;
+	lp->pdata->dim_freq_set = false;
+	lp->pdata->comp_config_set = false;
+	lp->pdata->filter_config_set = false;
+	lp->pdata->trim_config_set = false;
+
+	ret = of_property_read_string(node, "label", &lp->pdata->name);
+	if (ret < 0)
+		lp->pdata->name = NULL;
+
+	ret = of_property_read_u32(node, "default-brightness", &prog_val);
+	if (ret < 0)
+		prog_val = s_ibright;
+	lp->pdata->initial_brightness = prog_val;
+	if (lp->pdata->initial_brightness > MAX_BRIGHTNESS)
+		lp->pdata->initial_brightness = MAX_BRIGHTNESS;
+
+	ret = of_property_read_u32(node, "arc,led-config-0", &prog_val);
+	if (ret == 0) {
+		lp->pdata->led_config_0 = (u8)prog_val;
+		lp->pdata->led_config_0_set = true;
+	}
+	ret = of_property_read_u32(node, "arc,led-config-1", &prog_val);
+	if (ret == 0) {
+		lp->pdata->led_config_1 = (u8)prog_val;
+		lp->pdata->led_config_1_set = true;
+	}
+	ret = of_property_read_u32(node, "arc,dim-freq", &prog_val);
+	if (ret == 0) {
+		lp->pdata->dim_freq = (u8)prog_val;
+		lp->pdata->dim_freq_set = true;
+	}
+	ret = of_property_read_u32(node, "arc,comp-config", &prog_val);
+	if (ret == 0) {
+		lp->pdata->comp_config = (u8)prog_val;
+		lp->pdata->comp_config_set = true;
+	}
+	ret = of_property_read_u32(node, "arc,filter-config", &prog_val);
+	if (ret == 0) {
+		lp->pdata->filter_config = (u8)prog_val;
+		lp->pdata->filter_config_set = true;
+	}
+	ret = of_property_read_u32(node, "arc,trim-config", &prog_val);
+	if (ret == 0) {
+		lp->pdata->trim_config = (u8)prog_val;
+		lp->pdata->trim_config_set = true;
+	}
+	ret = of_property_count_u32_elems(node, "led-sources");
+	if (ret < 0)
+		lp->pdata->led_str = 0x3F;
+	else {
+		num_entry = ret;
+		if (num_entry > 6)
+			num_entry = 6;
+
+		ret = of_property_read_u32_array(node, "led-sources", sources,
+					num_entry);
+		if (ret < 0) {
+			dev_err(dev, "led-sources node is invalid.\n");
+			return -EINVAL;
+		}
+
+		lp->pdata->led_str = 0;
+		while (num_entry > 0)
+			lp->pdata->led_str |= (1 << sources[--num_entry]);
+	}
+	return 0;
+}
+#else
+static int arcxcnn_parse_dt(struct arcxcnn *lp)
+{
+	return -EINVAL;
+}
+#endif
+
+static int arcxcnn_probe(struct i2c_client *cl, const struct i2c_device_id *id)
+{
+	struct arcxcnn *lp;
+	int ret;
+	u8 regval;
+	u16 chipid;
+
+	if (!i2c_check_functionality(cl->adapter, I2C_FUNC_SMBUS_BYTE_DATA))
+		return -EIO;
+
+	lp = devm_kzalloc(&cl->dev, sizeof(*lp), GFP_KERNEL);
+	if (!lp)
+		return -ENOMEM;
+
+	lp->client = cl;
+	lp->dev = &cl->dev;
+	lp->chip_id = id->driver_data;
+	lp->pdata = dev_get_platdata(&cl->dev);
+
+	if (!lp->pdata) {
+		lp->pdata = devm_kzalloc(lp->dev,
+				sizeof(*lp->pdata), GFP_KERNEL);
+		if (!lp->pdata)
+			return -ENOMEM;
+
+		/* no platform data, parse the device-tree for info.  if there
+		 * is no device tree entry, we are being told we exist because
+		 * user-land said so, so make up the info we need
+		 */
+		ret = arcxcnn_parse_dt(lp);
+		if (ret < 0) {
+			/* no device tree, use defaults based on module params
+			 */
+			lp->pdata->led_config_0_set = false;
+			lp->pdata->led_config_1_set = false;
+			lp->pdata->dim_freq_set = false;
+			lp->pdata->comp_config_set = false;
+			lp->pdata->filter_config_set = false;
+			lp->pdata->trim_config_set = false;
+
+			lp->pdata->name = NULL;
+			lp->pdata->initial_brightness = s_ibright;
+			lp->pdata->led_str = s_iledstr;
+		}
+	}
+
+	if (lp->pdata->dim_freq_set)
+		lp->mode = PWM_BASED;
+	else
+		lp->mode = REGISTER_BASED;
+
+	i2c_set_clientdata(cl, lp);
+
+	/* read device ID */
+	regval = arcxcnn_read_byte(lp, 0x1E);
+	chipid = regval;
+	chipid <<= 8;
+	regval = arcxcnn_read_byte(lp, 0x1F);
+	chipid |= regval;
+
+	/* make sure it belongs to this driver
+	 * TODO - handle specific ids
+	 */
+	if (chipid != 0x02A5) {
+		#if 1
+		dev_info(&cl->dev, "Chip Id is %04X\n", chipid);
+		#else
+		dev_err(&cl->dev, "%04X is not ARC2C\n", chipid);
+		return -ENODEV;
+		#endif
+	}
+	/* reset the device */
+	arcxcnn_write_byte(lp, ARCXCNN_CMD, ARCXCNN_CMD_RESET);
+
+	/* set initial brightness */
+	arcxcnn_set_brightness(lp, lp->pdata->initial_brightness);
+
+	/* if fadectrl set in DT, set the value directly, else leave default */
+	if (lp->pdata->led_config_0_set)
+		arcxcnn_write_byte(lp, ARCXCNN_FADECTRL,
+			lp->pdata->led_config_0);
+
+	/* if iled config set in DT, set the value, else internal mode */
+	if (lp->pdata->led_config_1_set)
+		arcxcnn_write_byte(lp, ARCXCNN_ILED_CONFIG,
+			lp->pdata->led_config_1);
+	else
+		arcxcnn_write_byte(lp, ARCXCNN_ILED_CONFIG, 0x57);
+
+	/* other misc DT settings */
+	if (lp->pdata->dim_freq_set)
+		arcxcnn_write_byte(lp, ARCXCNN_FADECTRL, lp->pdata->dim_freq);
+	if (lp->pdata->comp_config_set)
+		arcxcnn_write_byte(lp, ARCXCNN_COMP_CONFIG,
+			lp->pdata->comp_config);
+	if (lp->pdata->filter_config_set)
+		arcxcnn_write_byte(lp, ARCXCNN_FILT_CONFIG,
+			lp->pdata->filter_config);
+	if (lp->pdata->trim_config_set)
+		arcxcnn_write_byte(lp, ARCXCNN_IMAXTUNE,
+			lp->pdata->trim_config);
+
+	/* set initial LED Strings */
+	arcxcnn_update_bit(lp, ARCXCNN_LEDEN,
+		ARCXCNN_LEDEN_MASK, lp->pdata->led_str);
+
+	snprintf(lp->chipname, sizeof(lp->chipname),
+		"%s-%04X", id->name, chipid);
+
+	ret = arcxcnn_backlight_register(lp);
+	if (ret) {
+		dev_err(lp->dev,
+			"failed to register backlight. err: %d\n", ret);
+		return ret;
+	}
+
+	ret = sysfs_create_group(&lp->dev->kobj, &arcxcnn_attr_group);
+	if (ret) {
+		dev_err(lp->dev, "failed to register sysfs. err: %d\n", ret);
+		return ret;
+	}
+
+	backlight_update_status(lp->bl);
+	return 0;
+}
+
+static int arcxcnn_remove(struct i2c_client *cl)
+{
+	struct arcxcnn *lp = i2c_get_clientdata(cl);
+
+	if (!s_no_reset_on_remove) {
+		/* disable all strings */
+		arcxcnn_write_byte(lp, ARCXCNN_LEDEN, 0x00);
+		/* reset the device */
+		arcxcnn_write_byte(lp, ARCXCNN_CMD, ARCXCNN_CMD_RESET);
+	}
+	lp->bl->props.brightness = 0;
+	backlight_update_status(lp->bl);
+	if (lp->supply)
+		regulator_disable(lp->supply);
+	sysfs_remove_group(&lp->dev->kobj, &arcxcnn_attr_group);
+
+	return 0;
+}
+
+static const struct of_device_id arcxcnn_dt_ids[] = {
+	{ .compatible = "arc,arc2c0608" },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, arcxcnn_dt_ids);
+
+/* Note that the device/chip ID is not fixed in silicon so
+ * auto-probing of these devices on the bus is most likely
+ * not possible, use device tree to set i2c bus address
+ */
+static const struct i2c_device_id arcxcnn_ids[] = {
+	{"arc2c0608", ARC2C0608},
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, arcxcnn_ids);
+
+static struct i2c_driver arcxcnn_driver = {
+	.driver = {
+		   .name = "arcxcnn_bl",
+		   .of_match_table = of_match_ptr(arcxcnn_dt_ids),
+		   },
+	.probe = arcxcnn_probe,
+	.remove = arcxcnn_remove,
+	.id_table = arcxcnn_ids,
+};
+
+module_i2c_driver(arcxcnn_driver);
+
+MODULE_LICENSE("GPL v2");
+MODULE_AUTHOR("Brian Dodge <bdodge09@outlook.com>");
+MODULE_DESCRIPTION("ARCXCNN Backlight driver");
diff --git a/include/linux/i2c/arcxcnn.h b/include/linux/i2c/arcxcnn.h
new file mode 100644
index 0000000..1c681dd
--- /dev/null
+++ b/include/linux/i2c/arcxcnn.h
@@ -0,0 +1,67 @@
+/*
+ * Backlight driver for ArcticSand ARC2C0608 Backlight Devices
+ *
+ * Copyright 2016 ArcticSand, Inc.
+ *
+ * Licensed under the GPL-2 or later.
+ */
+
+#ifndef _ARCXCNN_H
+#define _ARCXCNN_H
+
+enum arcxcnn_chip_id {
+	ARC2C0608
+};
+
+enum arcxcnn_brightness_source {
+	ARCXCNN_PWM_ONLY,
+	ARCXCNN_I2C_ONLY = 2,
+};
+
+#define ARCXCNN_MAX_PROGENTRIES	48	/* max a/v pairs for custom */
+
+/**
+ * struct arcxcnn_platform_data
+ * @name : Backlight driver name. If it is not defined, default name is set.
+ * @initial_brightness : initial value of backlight brightness
+ * @led_str	 : initial LED string enables, upper bit is global on/off
+ * @led_config_0 : fading speed (period between intensity steps)
+ * @led_config_1 : misc settings, see datasheet
+ * @dim_freq	 : pwm dimming frequency if in pwm mode
+ * @comp_config	 : misc config, see datasheet
+ * @filter_config: RC/PWM filter config, see datasheet
+ * @trim_config	 : full scale current trim, see datasheet
+ * @led_config_0_set	: the value in led_config_0 is valid
+ * @led_config_1_set	: the value in led_config_1 is valid
+ * @dim_freq_set	: the value in dim_freq is valid
+ * @comp_config_set	: the value in comp_config is valid
+ * @filter_config_set	: the value in filter_config is valid
+ * @trim_config_set	: the value in trim_config is valid
+ *
+ * the _set flags are used to indicate that the value was explicitly set
+ * in the device tree or platform data. settings not set are left as default
+ * power-on default values of the chip except for led_str and led_config_1
+ * which are set by the driver (led_str is specified indirectly in the
+ * device tree via "led-sources")
+ */
+struct arcxcnn_platform_data {
+	const char *name;
+	u16 initial_brightness;
+	u8	led_str;
+
+	u8	led_config_0;
+	u8	led_config_1;
+	u8	dim_freq;
+	u8	comp_config;
+	u8	filter_config;
+	u8	trim_config;
+
+	bool	led_config_0_set;
+	bool	led_config_1_set;
+	bool	dim_freq_set;
+	bool	comp_config_set;
+	bool	filter_config_set;
+	bool	trim_config_set;
+};
+
+#endif
-- 
2.7.4

Re: [PATCH 1/2] backlight: arcxcnn: add support for ArticSand devices

[Lee Jones]

On Fri, 18 Nov 2016, Olimpiu Dejeu wrote:

> Re-submission of arcxcnn backlight driver addressing the naming convention
>  concerns raised by Rob H.
> 
> Signed-off-by: Olimpiu Dejeu <olimpiu@arcticsand.com>
> 
> ---
>  drivers/video/backlight/Kconfig      |   7 +
>  drivers/video/backlight/Makefile     |   1 +
>  drivers/video/backlight/arcxcnn_bl.c | 541 +++++++++++++++++++++++++++++++++++
>  include/linux/i2c/arcxcnn.h          |  67 +++++
>  4 files changed, 616 insertions(+)
>  create mode 100644 drivers/video/backlight/arcxcnn_bl.c
>  create mode 100644 include/linux/i2c/arcxcnn.h

Same goes for this patch.

Also, make sure you submit you patches so that they are connected in
people's inboxes.

Use `git send-email` where --thread should be the default.

> diff --git a/drivers/video/backlight/Kconfig b/drivers/video/backlight/Kconfig
> index 5ffa4b4..4e1d2ad 100644
> --- a/drivers/video/backlight/Kconfig
> +++ b/drivers/video/backlight/Kconfig
> @@ -460,6 +460,13 @@ config BACKLIGHT_BD6107
>  	help
>  	  If you have a Rohm BD6107 say Y to enable the backlight driver.
>  
> +config BACKLIGHT_ARCXCNN
> +	tristate "Backlight driver for the Arctic Sands ARCxCnnnn family"
> +	depends on I2C
> +	help
> +	  If you have an ARCxCnnnn family backlight say Y to enable
> +	  the backlight driver.
> +
>  endif # BACKLIGHT_CLASS_DEVICE
>  
>  endif # BACKLIGHT_LCD_SUPPORT
> diff --git a/drivers/video/backlight/Makefile b/drivers/video/backlight/Makefile
> index 16ec534..8905129 100644
> --- a/drivers/video/backlight/Makefile
> +++ b/drivers/video/backlight/Makefile
> @@ -55,3 +55,4 @@ obj-$(CONFIG_BACKLIGHT_SKY81452)	+= sky81452-backlight.o
>  obj-$(CONFIG_BACKLIGHT_TOSA)		+= tosa_bl.o
>  obj-$(CONFIG_BACKLIGHT_TPS65217)	+= tps65217_bl.o
>  obj-$(CONFIG_BACKLIGHT_WM831X)		+= wm831x_bl.o
> +obj-$(CONFIG_BACKLIGHT_ARCXCNN) 	+= arcxcnn_bl.o
> diff --git a/drivers/video/backlight/arcxcnn_bl.c b/drivers/video/backlight/arcxcnn_bl.c
> new file mode 100644
> index 0000000..1dad680
> --- /dev/null
> +++ b/drivers/video/backlight/arcxcnn_bl.c
> @@ -0,0 +1,541 @@
> +/*
> + * Backlight driver for ArcticSand ARC_X_C_0N_0N Devices
> + *
> + * Copyright 2016 ArcticSand, Inc.
> + *
> + * Licensed under the GPL-2 or later.
> + */
> +
> +#include <linux/module.h>
> +#include <linux/slab.h>
> +#include <linux/i2c.h>
> +#include <linux/backlight.h>
> +#include <linux/err.h>
> +#include <linux/of.h>
> +#include <linux/pwm.h>
> +#include <linux/regulator/consumer.h>
> +
> +#include "linux/i2c/arcxcnn.h"
> +
> +#define ARCXCNN_CMD		(0x00)  /* Command Register */
> +#define ARCXCNN_CMD_STDBY	(0x80)	/* I2C Standby */
> +#define ARCXCNN_CMD_RESET	(0x40)	/* Reset */
> +#define ARCXCNN_CMD_BOOST	(0x10)	/* Boost */
> +#define ARCXCNN_CMD_OVP_MASK	(0x0C)	/* --- Over Voltage Threshold */
> +#define ARCXCNN_CMD_OVP_XXV	(0x0C)	/* <rsvrd> Over Voltage Threshold */
> +#define ARCXCNN_CMD_OVP_20V	(0x08)	/* 20v Over Voltage Threshold */
> +#define ARCXCNN_CMD_OVP_24V	(0x04)	/* 24v Over Voltage Threshold */
> +#define ARCXCNN_CMD_OVP_31V	(0x00)	/* 31.4v Over Voltage Threshold */
> +#define ARCXCNN_CMD_EXT_COMP	(0x01)	/* part (0) or full (1) external comp */
> +
> +#define ARCXCNN_CONFIG	(0x01)  /* Configuration */
> +#define ARCXCNN_STATUS1	(0x02)  /* Status 1 */
> +#define ARCXCNN_STATUS2	(0x03)  /* Status 2 */
> +#define ARCXCNN_FADECTRL	(0x04)  /* Fading Control */
> +#define ARCXCNN_ILED_CONFIG	(0x05)  /* ILED Configuration */
> +
> +#define ARCXCNN_LEDEN		(0x06)  /* LED Enable Register */
> +#define ARCXCNN_LEDEN_ISETEXT	(0x80)	/* Full-scale current set externally */
> +#define ARCXCNN_LEDEN_MASK	(0x3F)	/* LED string enables */
> +#define ARCXCNN_LEDEN_LED1	(0x01)
> +#define ARCXCNN_LEDEN_LED2	(0x02)
> +#define ARCXCNN_LEDEN_LED3	(0x04)
> +#define ARCXCNN_LEDEN_LED4	(0x08)
> +#define ARCXCNN_LEDEN_LED5	(0x10)
> +#define ARCXCNN_LEDEN_LED6	(0x20)
> +
> +#define ARCXCNN_WLED_ISET_LSB	(0x07)  /* LED ISET LSB (in upper nibble) */
> +#define ARCXCNN_WLED_ISET_MSB	(0x08)  /* LED ISET MSB (8 bits) */
> +
> +#define ARCXCNN_DIMFREQ		(0x09)
> +#define ARCXCNN_COMP_CONFIG	(0x0A)
> +#define ARCXCNN_FILT_CONFIG	(0x0B)
> +#define ARCXCNN_IMAXTUNE	(0x0C)
> +
> +#define DEFAULT_BL_NAME		"arctic_bl"
> +#define MAX_BRIGHTNESS		4095
> +
> +static int s_no_reset_on_remove;
> +module_param_named(noreset, s_no_reset_on_remove, int, 0644);
> +MODULE_PARM_DESC(noreset, "No reset on module removal");
> +
> +static int s_ibright = 60;
> +module_param_named(ibright, s_ibright, int, 0644);
> +MODULE_PARM_DESC(ibright, "Initial brightness (when no plat data)");
> +
> +static int s_iledstr = 0x3F;
> +module_param_named(iledstr, s_iledstr, int, 0644);
> +MODULE_PARM_DESC(iledstr, "Initial LED String (when no plat data)");
> +
> +static int s_retries = 2; /* 1 == only one try */
> +module_param_named(retries, s_retries, int, 0644);
> +MODULE_PARM_DESC(retries, "I2C retries attempted");
> +
> +enum arcxcnn_brightness_ctrl_mode {
> +	PWM_BASED = 1,
> +	REGISTER_BASED,
> +};
> +
> +struct arcxcnn;
> +
> +struct arcxcnn {
> +	char chipname[64];
> +	enum arcxcnn_chip_id chip_id;
> +	enum arcxcnn_brightness_ctrl_mode mode;
> +	struct i2c_client *client;
> +	struct backlight_device *bl;
> +	struct device *dev;
> +	struct arcxcnn_platform_data *pdata;
> +	struct pwm_device *pwm;
> +	struct regulator *supply;	/* regulator for VDD input */
> +};
> +
> +static int arcxcnn_write_byte(struct arcxcnn *lp, u8 reg, u8 data)
> +{
> +	s32 ret = -1;
> +	int att;
> +
> +	for (att = 0; att < s_retries; att++) {
> +		ret = i2c_smbus_write_byte_data(lp->client, reg, data);
> +		if (ret >= 0)
> +			return 0;
> +	}
> +	return ret;
> +}
> +
> +static u8 arcxcnn_read_byte(struct arcxcnn *lp, u8 reg)
> +{
> +	int val;
> +	int att;
> +
> +	for (att = 0; att < s_retries; att++) {
> +		val = i2c_smbus_read_byte_data(lp->client, reg);
> +		if (val >= 0)
> +			return (u8)val;
> +	}
> +	return 0;
> +}
> +
> +static int arcxcnn_update_bit(struct arcxcnn *lp, u8 reg, u8 mask, u8 data)
> +{
> +	int ret, att;
> +	u8 tmp;
> +
> +	for (att = 0, ret = -1; att < s_retries; att++) {
> +		ret = i2c_smbus_read_byte_data(lp->client, reg);
> +		if (ret >= 0)
> +			break;
> +	}
> +	if (ret < 0) {
> +		dev_err(lp->dev, "failed to read 0x%.2x\n", reg);
> +		return ret;
> +	}
> +
> +	tmp = (u8)ret;
> +	tmp &= ~mask;
> +	tmp |= data & mask;
> +
> +	return arcxcnn_write_byte(lp, reg, tmp);
> +}
> +
> +static int arcxcnn_set_brightness(struct arcxcnn *lp, u32 brightness)
> +{
> +	int ret;
> +	u8 val;
> +
> +	val = (brightness & 0xF) << 4;
> +	ret = arcxcnn_write_byte(lp, ARCXCNN_WLED_ISET_LSB, val);
> +	if (ret < 0)
> +		return ret;
> +	val = (brightness >> 4);
> +	ret = arcxcnn_write_byte(lp, ARCXCNN_WLED_ISET_MSB, val);
> +	return ret;
> +}
> +
> +static int arcxcnn_bl_update_status(struct backlight_device *bl)
> +{
> +	struct arcxcnn *lp = bl_get_data(bl);
> +	u32 brightness = bl->props.brightness;
> +
> +	if (bl->props.state & (BL_CORE_SUSPENDED | BL_CORE_FBBLANK))
> +		brightness = 0;
> +
> +	/* set brightness */
> +	if (lp->mode == PWM_BASED)
> +		; /* via pwm */
> +	else if (lp->mode == REGISTER_BASED)
> +		arcxcnn_set_brightness(lp, brightness);
> +
> +	/* set power-on/off/save modes */
> +	if (bl->props.power == 0)
> +		/* take out of standby */
> +		arcxcnn_update_bit(lp, ARCXCNN_CMD, ARCXCNN_CMD_STDBY, 0);
> +	else
> +		/* 1-3 == power save, 4 = off
> +		 * place in low-power standby mode
> +		 */
> +		arcxcnn_update_bit(lp, ARCXCNN_CMD,
> +				ARCXCNN_CMD_STDBY, ARCXCNN_CMD_STDBY);
> +	return 0;
> +}
> +
> +static const struct backlight_ops arcxcnn_bl_ops = {
> +	.options = BL_CORE_SUSPENDRESUME,
> +	.update_status = arcxcnn_bl_update_status,
> +};
> +
> +static int arcxcnn_backlight_register(struct arcxcnn *lp)
> +{
> +	struct backlight_device *bl;
> +	struct backlight_properties props;
> +	struct arcxcnn_platform_data *pdata = lp->pdata;
> +	const char *name = pdata->name ? : DEFAULT_BL_NAME;
> +
> +	memset(&props, 0, sizeof(props));
> +	props.type = BACKLIGHT_PLATFORM;
> +	props.max_brightness = MAX_BRIGHTNESS;
> +
> +	if (pdata->initial_brightness > props.max_brightness)
> +		pdata->initial_brightness = props.max_brightness;
> +
> +	props.brightness = pdata->initial_brightness;
> +
> +	bl = devm_backlight_device_register(lp->dev, name, lp->dev, lp,
> +				       &arcxcnn_bl_ops, &props);
> +	if (IS_ERR(bl))
> +		return PTR_ERR(bl);
> +
> +	lp->bl = bl;
> +
> +	return 0;
> +}
> +
> +static ssize_t arcxcnn_get_chip_id(struct device *dev,
> +		struct device_attribute *attr, char *buf)
> +{
> +	struct arcxcnn *lp = dev_get_drvdata(dev);
> +
> +	return scnprintf(buf, PAGE_SIZE, "%s\n", lp->chipname);
> +}
> +
> +static ssize_t arcxcnn_get_led_str(struct device *dev,
> +		struct device_attribute *attr, char *buf)
> +{
> +	struct arcxcnn *lp = dev_get_drvdata(dev);
> +
> +	return scnprintf(buf, PAGE_SIZE, "%02X\n", lp->pdata->led_str);
> +}
> +
> +static ssize_t arcxcnn_set_led_str(struct device *dev,
> +		struct device_attribute *attr, const char *buf, size_t len)
> +{
> +	struct arcxcnn *lp = dev_get_drvdata(dev);
> +	unsigned long ledstr;
> +
> +	if (kstrtoul(buf, 0, &ledstr))
> +		return 0;
> +
> +	if (ledstr != lp->pdata->led_str) {
> +		/* don't allow 0 for ledstr, use power to turn all off */
> +		if (ledstr == 0)
> +			return 0;
> +		lp->pdata->led_str = ledstr & 0x3F;
> +		arcxcnn_update_bit(lp, ARCXCNN_LEDEN,
> +			ARCXCNN_LEDEN_MASK, lp->pdata->led_str);
> +	}
> +	return len;
> +}
> +
> +static ssize_t arcxcnn_get_bl_ctl_mode(struct device *dev,
> +	     struct device_attribute *attr, char *buf)
> +{
> +	struct arcxcnn *lp = dev_get_drvdata(dev);
> +	char *strmode = NULL;
> +
> +	if (lp->mode == PWM_BASED)
> +		strmode = "pwm based";
> +	else if (lp->mode == REGISTER_BASED)
> +		strmode = "register based";
> +
> +	return scnprintf(buf, PAGE_SIZE, "%s\n", strmode);
> +}
> +
> +static DEVICE_ATTR(chip_id, 0444, arcxcnn_get_chip_id, NULL);
> +static DEVICE_ATTR(led_str, 0664, arcxcnn_get_led_str, arcxcnn_set_led_str);
> +static DEVICE_ATTR(bl_ctl_mode, 0444, arcxcnn_get_bl_ctl_mode, NULL);
> +
> +static struct attribute *arcxcnn_attributes[] = {
> +	&dev_attr_chip_id.attr,
> +	&dev_attr_led_str.attr,
> +	&dev_attr_bl_ctl_mode.attr,
> +	NULL,
> +};
> +
> +static const struct attribute_group arcxcnn_attr_group = {
> +	.attrs = arcxcnn_attributes,
> +};
> +
> +#ifdef CONFIG_OF
> +static int arcxcnn_parse_dt(struct arcxcnn *lp)
> +{
> +	struct device *dev = lp->dev;
> +	struct device_node *node = dev->of_node;
> +	u32 prog_val, num_entry, sources[6];
> +	int ret;
> +
> +	if (!node) {
> +		dev_err(dev, "no platform data.\n");
> +		return -EINVAL;
> +	}
> +	lp->pdata->led_config_0_set = false;
> +	lp->pdata->led_config_1_set = false;
> +	lp->pdata->dim_freq_set = false;
> +	lp->pdata->comp_config_set = false;
> +	lp->pdata->filter_config_set = false;
> +	lp->pdata->trim_config_set = false;
> +
> +	ret = of_property_read_string(node, "label", &lp->pdata->name);
> +	if (ret < 0)
> +		lp->pdata->name = NULL;
> +
> +	ret = of_property_read_u32(node, "default-brightness", &prog_val);
> +	if (ret < 0)
> +		prog_val = s_ibright;
> +	lp->pdata->initial_brightness = prog_val;
> +	if (lp->pdata->initial_brightness > MAX_BRIGHTNESS)
> +		lp->pdata->initial_brightness = MAX_BRIGHTNESS;
> +
> +	ret = of_property_read_u32(node, "arc,led-config-0", &prog_val);
> +	if (ret == 0) {
> +		lp->pdata->led_config_0 = (u8)prog_val;
> +		lp->pdata->led_config_0_set = true;
> +	}
> +	ret = of_property_read_u32(node, "arc,led-config-1", &prog_val);
> +	if (ret == 0) {
> +		lp->pdata->led_config_1 = (u8)prog_val;
> +		lp->pdata->led_config_1_set = true;
> +	}
> +	ret = of_property_read_u32(node, "arc,dim-freq", &prog_val);
> +	if (ret == 0) {
> +		lp->pdata->dim_freq = (u8)prog_val;
> +		lp->pdata->dim_freq_set = true;
> +	}
> +	ret = of_property_read_u32(node, "arc,comp-config", &prog_val);
> +	if (ret == 0) {
> +		lp->pdata->comp_config = (u8)prog_val;
> +		lp->pdata->comp_config_set = true;
> +	}
> +	ret = of_property_read_u32(node, "arc,filter-config", &prog_val);
> +	if (ret == 0) {
> +		lp->pdata->filter_config = (u8)prog_val;
> +		lp->pdata->filter_config_set = true;
> +	}
> +	ret = of_property_read_u32(node, "arc,trim-config", &prog_val);
> +	if (ret == 0) {
> +		lp->pdata->trim_config = (u8)prog_val;
> +		lp->pdata->trim_config_set = true;
> +	}
> +	ret = of_property_count_u32_elems(node, "led-sources");
> +	if (ret < 0)
> +		lp->pdata->led_str = 0x3F;
> +	else {
> +		num_entry = ret;
> +		if (num_entry > 6)
> +			num_entry = 6;
> +
> +		ret = of_property_read_u32_array(node, "led-sources", sources,
> +					num_entry);
> +		if (ret < 0) {
> +			dev_err(dev, "led-sources node is invalid.\n");
> +			return -EINVAL;
> +		}
> +
> +		lp->pdata->led_str = 0;
> +		while (num_entry > 0)
> +			lp->pdata->led_str |= (1 << sources[--num_entry]);
> +	}
> +	return 0;
> +}
> +#else
> +static int arcxcnn_parse_dt(struct arcxcnn *lp)
> +{
> +	return -EINVAL;
> +}
> +#endif
> +
> +static int arcxcnn_probe(struct i2c_client *cl, const struct i2c_device_id *id)
> +{
> +	struct arcxcnn *lp;
> +	int ret;
> +	u8 regval;
> +	u16 chipid;
> +
> +	if (!i2c_check_functionality(cl->adapter, I2C_FUNC_SMBUS_BYTE_DATA))
> +		return -EIO;
> +
> +	lp = devm_kzalloc(&cl->dev, sizeof(*lp), GFP_KERNEL);
> +	if (!lp)
> +		return -ENOMEM;
> +
> +	lp->client = cl;
> +	lp->dev = &cl->dev;
> +	lp->chip_id = id->driver_data;
> +	lp->pdata = dev_get_platdata(&cl->dev);
> +
> +	if (!lp->pdata) {
> +		lp->pdata = devm_kzalloc(lp->dev,
> +				sizeof(*lp->pdata), GFP_KERNEL);
> +		if (!lp->pdata)
> +			return -ENOMEM;
> +
> +		/* no platform data, parse the device-tree for info.  if there
> +		 * is no device tree entry, we are being told we exist because
> +		 * user-land said so, so make up the info we need
> +		 */
> +		ret = arcxcnn_parse_dt(lp);
> +		if (ret < 0) {
> +			/* no device tree, use defaults based on module params
> +			 */
> +			lp->pdata->led_config_0_set = false;
> +			lp->pdata->led_config_1_set = false;
> +			lp->pdata->dim_freq_set = false;
> +			lp->pdata->comp_config_set = false;
> +			lp->pdata->filter_config_set = false;
> +			lp->pdata->trim_config_set = false;
> +
> +			lp->pdata->name = NULL;
> +			lp->pdata->initial_brightness = s_ibright;
> +			lp->pdata->led_str = s_iledstr;
> +		}
> +	}
> +
> +	if (lp->pdata->dim_freq_set)
> +		lp->mode = PWM_BASED;
> +	else
> +		lp->mode = REGISTER_BASED;
> +
> +	i2c_set_clientdata(cl, lp);
> +
> +	/* read device ID */
> +	regval = arcxcnn_read_byte(lp, 0x1E);
> +	chipid = regval;
> +	chipid <<= 8;
> +	regval = arcxcnn_read_byte(lp, 0x1F);
> +	chipid |= regval;
> +
> +	/* make sure it belongs to this driver
> +	 * TODO - handle specific ids
> +	 */
> +	if (chipid != 0x02A5) {
> +		#if 1
> +		dev_info(&cl->dev, "Chip Id is %04X\n", chipid);
> +		#else
> +		dev_err(&cl->dev, "%04X is not ARC2C\n", chipid);
> +		return -ENODEV;
> +		#endif
> +	}
> +	/* reset the device */
> +	arcxcnn_write_byte(lp, ARCXCNN_CMD, ARCXCNN_CMD_RESET);
> +
> +	/* set initial brightness */
> +	arcxcnn_set_brightness(lp, lp->pdata->initial_brightness);
> +
> +	/* if fadectrl set in DT, set the value directly, else leave default */
> +	if (lp->pdata->led_config_0_set)
> +		arcxcnn_write_byte(lp, ARCXCNN_FADECTRL,
> +			lp->pdata->led_config_0);
> +
> +	/* if iled config set in DT, set the value, else internal mode */
> +	if (lp->pdata->led_config_1_set)
> +		arcxcnn_write_byte(lp, ARCXCNN_ILED_CONFIG,
> +			lp->pdata->led_config_1);
> +	else
> +		arcxcnn_write_byte(lp, ARCXCNN_ILED_CONFIG, 0x57);
> +
> +	/* other misc DT settings */
> +	if (lp->pdata->dim_freq_set)
> +		arcxcnn_write_byte(lp, ARCXCNN_FADECTRL, lp->pdata->dim_freq);
> +	if (lp->pdata->comp_config_set)
> +		arcxcnn_write_byte(lp, ARCXCNN_COMP_CONFIG,
> +			lp->pdata->comp_config);
> +	if (lp->pdata->filter_config_set)
> +		arcxcnn_write_byte(lp, ARCXCNN_FILT_CONFIG,
> +			lp->pdata->filter_config);
> +	if (lp->pdata->trim_config_set)
> +		arcxcnn_write_byte(lp, ARCXCNN_IMAXTUNE,
> +			lp->pdata->trim_config);
> +
> +	/* set initial LED Strings */
> +	arcxcnn_update_bit(lp, ARCXCNN_LEDEN,
> +		ARCXCNN_LEDEN_MASK, lp->pdata->led_str);
> +
> +	snprintf(lp->chipname, sizeof(lp->chipname),
> +		"%s-%04X", id->name, chipid);
> +
> +	ret = arcxcnn_backlight_register(lp);
> +	if (ret) {
> +		dev_err(lp->dev,
> +			"failed to register backlight. err: %d\n", ret);
> +		return ret;
> +	}
> +
> +	ret = sysfs_create_group(&lp->dev->kobj, &arcxcnn_attr_group);
> +	if (ret) {
> +		dev_err(lp->dev, "failed to register sysfs. err: %d\n", ret);
> +		return ret;
> +	}
> +
> +	backlight_update_status(lp->bl);
> +	return 0;
> +}
> +
> +static int arcxcnn_remove(struct i2c_client *cl)
> +{
> +	struct arcxcnn *lp = i2c_get_clientdata(cl);
> +
> +	if (!s_no_reset_on_remove) {
> +		/* disable all strings */
> +		arcxcnn_write_byte(lp, ARCXCNN_LEDEN, 0x00);
> +		/* reset the device */
> +		arcxcnn_write_byte(lp, ARCXCNN_CMD, ARCXCNN_CMD_RESET);
> +	}
> +	lp->bl->props.brightness = 0;
> +	backlight_update_status(lp->bl);
> +	if (lp->supply)
> +		regulator_disable(lp->supply);
> +	sysfs_remove_group(&lp->dev->kobj, &arcxcnn_attr_group);
> +
> +	return 0;
> +}
> +
> +static const struct of_device_id arcxcnn_dt_ids[] = {
> +	{ .compatible = "arc,arc2c0608" },
> +	{ }
> +};
> +MODULE_DEVICE_TABLE(of, arcxcnn_dt_ids);
> +
> +/* Note that the device/chip ID is not fixed in silicon so
> + * auto-probing of these devices on the bus is most likely
> + * not possible, use device tree to set i2c bus address
> + */
> +static const struct i2c_device_id arcxcnn_ids[] = {
> +	{"arc2c0608", ARC2C0608},
> +	{ }
> +};
> +MODULE_DEVICE_TABLE(i2c, arcxcnn_ids);
> +
> +static struct i2c_driver arcxcnn_driver = {
> +	.driver = {
> +		   .name = "arcxcnn_bl",
> +		   .of_match_table = of_match_ptr(arcxcnn_dt_ids),
> +		   },
> +	.probe = arcxcnn_probe,
> +	.remove = arcxcnn_remove,
> +	.id_table = arcxcnn_ids,
> +};
> +
> +module_i2c_driver(arcxcnn_driver);
> +
> +MODULE_LICENSE("GPL v2");
> +MODULE_AUTHOR("Brian Dodge <bdodge09@outlook.com>");
> +MODULE_DESCRIPTION("ARCXCNN Backlight driver");
> diff --git a/include/linux/i2c/arcxcnn.h b/include/linux/i2c/arcxcnn.h
> new file mode 100644
> index 0000000..1c681dd
> --- /dev/null
> +++ b/include/linux/i2c/arcxcnn.h
> @@ -0,0 +1,67 @@
> +/*
> + * Backlight driver for ArcticSand ARC2C0608 Backlight Devices
> + *
> + * Copyright 2016 ArcticSand, Inc.
> + *
> + * Licensed under the GPL-2 or later.
> + */
> +
> +#ifndef _ARCXCNN_H
> +#define _ARCXCNN_H
> +
> +enum arcxcnn_chip_id {
> +	ARC2C0608
> +};
> +
> +enum arcxcnn_brightness_source {
> +	ARCXCNN_PWM_ONLY,
> +	ARCXCNN_I2C_ONLY = 2,
> +};
> +
> +#define ARCXCNN_MAX_PROGENTRIES	48	/* max a/v pairs for custom */
> +
> +/**
> + * struct arcxcnn_platform_data
> + * @name : Backlight driver name. If it is not defined, default name is set.
> + * @initial_brightness : initial value of backlight brightness
> + * @led_str	 : initial LED string enables, upper bit is global on/off
> + * @led_config_0 : fading speed (period between intensity steps)
> + * @led_config_1 : misc settings, see datasheet
> + * @dim_freq	 : pwm dimming frequency if in pwm mode
> + * @comp_config	 : misc config, see datasheet
> + * @filter_config: RC/PWM filter config, see datasheet
> + * @trim_config	 : full scale current trim, see datasheet
> + * @led_config_0_set	: the value in led_config_0 is valid
> + * @led_config_1_set	: the value in led_config_1 is valid
> + * @dim_freq_set	: the value in dim_freq is valid
> + * @comp_config_set	: the value in comp_config is valid
> + * @filter_config_set	: the value in filter_config is valid
> + * @trim_config_set	: the value in trim_config is valid
> + *
> + * the _set flags are used to indicate that the value was explicitly set
> + * in the device tree or platform data. settings not set are left as default
> + * power-on default values of the chip except for led_str and led_config_1
> + * which are set by the driver (led_str is specified indirectly in the
> + * device tree via "led-sources")
> + */
> +struct arcxcnn_platform_data {
> +	const char *name;
> +	u16 initial_brightness;
> +	u8	led_str;
> +
> +	u8	led_config_0;
> +	u8	led_config_1;
> +	u8	dim_freq;
> +	u8	comp_config;
> +	u8	filter_config;
> +	u8	trim_config;
> +
> +	bool	led_config_0_set;
> +	bool	led_config_1_set;
> +	bool	dim_freq_set;
> +	bool	comp_config_set;
> +	bool	filter_config_set;
> +	bool	trim_config_set;
> +};
> +
> +#endif

-- 
Lee Jones
Linaro STMicroelectronics Landing Team Lead
Linaro.org │ Open source software for ARM SoCs
Follow Linaro: Facebook | Twitter | Blog

Re: [PATCH 1/2] backlight: arcxcnn: add support for ArticSand devices

[Lee Jones]

I'll give this a quick once over, but Jingoo will also need to review.

On Thu, 10 Nov 2016, Olimpiu Dejeu wrote:

> Resubmition of arcxcnn backlight driver addressing the naming convention
>  concerns raised by Rob H.

This is not a commit log.  It's a changelog which lives at <####>.

> Signed-off-by: Olimpiu Dejeu <olimpiu@arcticsand.com>
> 
> ---

<####>

>  drivers/video/backlight/Kconfig      |   7 +
>  drivers/video/backlight/Makefile     |   1 +
>  drivers/video/backlight/arcxcnn_bl.c | 541 +++++++++++++++++++++++++++++++++++
>  include/linux/i2c/arcxcnn.h          |  67 +++++
>  4 files changed, 616 insertions(+)
>  create mode 100644 drivers/video/backlight/arcxcnn_bl.c
>  create mode 100644 include/linux/i2c/arcxcnn.h
> 
> diff --git a/drivers/video/backlight/Kconfig b/drivers/video/backlight/Kconfig
> index 5ffa4b4..4e1d2ad 100644
> --- a/drivers/video/backlight/Kconfig
> +++ b/drivers/video/backlight/Kconfig
> @@ -460,6 +460,13 @@ config BACKLIGHT_BD6107
>  	help
>  	  If you have a Rohm BD6107 say Y to enable the backlight driver.
>  
> +config BACKLIGHT_ARCXCNN
> +	tristate "Backlight driver for the Arctic Sands ARCxCnnnn family"
> +	depends on I2C
> +	help
> +	  If you have an ARCxCnnnn family backlight say Y to enable
> +	  the backlight driver.
> +
>  endif # BACKLIGHT_CLASS_DEVICE
>  
>  endif # BACKLIGHT_LCD_SUPPORT
> diff --git a/drivers/video/backlight/Makefile b/drivers/video/backlight/Makefile
> index 16ec534..8905129 100644
> --- a/drivers/video/backlight/Makefile
> +++ b/drivers/video/backlight/Makefile
> @@ -55,3 +55,4 @@ obj-$(CONFIG_BACKLIGHT_SKY81452)	+= sky81452-backlight.o
>  obj-$(CONFIG_BACKLIGHT_TOSA)		+= tosa_bl.o
>  obj-$(CONFIG_BACKLIGHT_TPS65217)	+= tps65217_bl.o
>  obj-$(CONFIG_BACKLIGHT_WM831X)		+= wm831x_bl.o
> +obj-$(CONFIG_BACKLIGHT_ARCXCNN) 	+= arcxcnn_bl.o
> diff --git a/drivers/video/backlight/arcxcnn_bl.c b/drivers/video/backlight/arcxcnn_bl.c
> new file mode 100644
> index 0000000..1dad680
> --- /dev/null
> +++ b/drivers/video/backlight/arcxcnn_bl.c
> @@ -0,0 +1,541 @@
> +/*
> + * Backlight driver for ArcticSand ARC_X_C_0N_0N Devices
> + *
> + * Copyright 2016 ArcticSand, Inc.
> + *
> + * Licensed under the GPL-2 or later.

As far as I'm aware, this does not constitude as a proper GPL licence
statement.

> + */
> +
> +#include <linux/module.h>
> +#include <linux/slab.h>
> +#include <linux/i2c.h>
> +#include <linux/backlight.h>
> +#include <linux/err.h>
> +#include <linux/of.h>
> +#include <linux/pwm.h>
> +#include <linux/regulator/consumer.h>

Alphabetical.

> +#include "linux/i2c/arcxcnn.h"
> +
> +#define ARCXCNN_CMD		(0x00)  /* Command Register */
> +#define ARCXCNN_CMD_STDBY	(0x80)	/* I2C Standby */
> +#define ARCXCNN_CMD_RESET	(0x40)	/* Reset */
> +#define ARCXCNN_CMD_BOOST	(0x10)	/* Boost */
> +#define ARCXCNN_CMD_OVP_MASK	(0x0C)	/* --- Over Voltage Threshold */
> +#define ARCXCNN_CMD_OVP_XXV	(0x0C)	/* <rsvrd> Over Voltage Threshold */
> +#define ARCXCNN_CMD_OVP_20V	(0x08)	/* 20v Over Voltage Threshold */
> +#define ARCXCNN_CMD_OVP_24V	(0x04)	/* 24v Over Voltage Threshold */
> +#define ARCXCNN_CMD_OVP_31V	(0x00)	/* 31.4v Over Voltage Threshold */
> +#define ARCXCNN_CMD_EXT_COMP	(0x01)	/* part (0) or full (1) external comp */
> +
> +#define ARCXCNN_CONFIG	(0x01)  /* Configuration */
> +#define ARCXCNN_STATUS1	(0x02)  /* Status 1 */
> +#define ARCXCNN_STATUS2	(0x03)  /* Status 2 */
> +#define ARCXCNN_FADECTRL	(0x04)  /* Fading Control */
> +#define ARCXCNN_ILED_CONFIG	(0x05)  /* ILED Configuration */
> +
> +#define ARCXCNN_LEDEN		(0x06)  /* LED Enable Register */
> +#define ARCXCNN_LEDEN_ISETEXT	(0x80)	/* Full-scale current set externally */
> +#define ARCXCNN_LEDEN_MASK	(0x3F)	/* LED string enables */
> +#define ARCXCNN_LEDEN_LED1	(0x01)
> +#define ARCXCNN_LEDEN_LED2	(0x02)
> +#define ARCXCNN_LEDEN_LED3	(0x04)
> +#define ARCXCNN_LEDEN_LED4	(0x08)
> +#define ARCXCNN_LEDEN_LED5	(0x10)
> +#define ARCXCNN_LEDEN_LED6	(0x20)
> +
> +#define ARCXCNN_WLED_ISET_LSB	(0x07)  /* LED ISET LSB (in upper nibble) */
> +#define ARCXCNN_WLED_ISET_MSB	(0x08)  /* LED ISET MSB (8 bits) */
> +
> +#define ARCXCNN_DIMFREQ		(0x09)
> +#define ARCXCNN_COMP_CONFIG	(0x0A)
> +#define ARCXCNN_FILT_CONFIG	(0x0B)
> +#define ARCXCNN_IMAXTUNE	(0x0C)

No need for simple defines to be place inside parenthesis.

> +#define DEFAULT_BL_NAME		"arctic_bl"

Don't do this.  Just use the name in the place you need to use it.

> +#define MAX_BRIGHTNESS		4095
> +
> +static int s_no_reset_on_remove;
> +module_param_named(noreset, s_no_reset_on_remove, int, 0644);
> +MODULE_PARM_DESC(noreset, "No reset on module removal");
> +
> +static int s_ibright = 60;
> +module_param_named(ibright, s_ibright, int, 0644);
> +MODULE_PARM_DESC(ibright, "Initial brightness (when no plat data)");
> +
> +static int s_iledstr = 0x3F;
> +module_param_named(iledstr, s_iledstr, int, 0644);
> +MODULE_PARM_DESC(iledstr, "Initial LED String (when no plat data)");
> +
> +static int s_retries = 2; /* 1 == only one try */
> +module_param_named(retries, s_retries, int, 0644);
> +MODULE_PARM_DESC(retries, "I2C retries attempted");
> +
> +enum arcxcnn_brightness_ctrl_mode {
> +	PWM_BASED = 1,
> +	REGISTER_BASED,
> +};
> +
> +struct arcxcnn;

Why?

> +struct arcxcnn {
> +	char chipname[64];
> +	enum arcxcnn_chip_id chip_id;
> +	enum arcxcnn_brightness_ctrl_mode mode;
> +	struct i2c_client *client;
> +	struct backlight_device *bl;
> +	struct device *dev;

You only need one of 'bl', 'dev' and 'client'.

> +	struct arcxcnn_platform_data *pdata;

pdata should not be stored in ddata.

> +	struct pwm_device *pwm;
> +	struct regulator *supply;	/* regulator for VDD input */
> +};

Document using kerneldoc.

> +static int arcxcnn_write_byte(struct arcxcnn *lp, u8 reg, u8 data)
> +{
> +	s32 ret = -1;
> +	int att;
> +
> +	for (att = 0; att < s_retries; att++) {

This is non-standard.

Why would it fail on first attempt and succeed on the next?

> +		ret = i2c_smbus_write_byte_data(lp->client, reg, data);
> +		if (ret >= 0)
> +			return 0;
> +	}
> +	return ret;
> +}
> +
> +static u8 arcxcnn_read_byte(struct arcxcnn *lp, u8 reg)
> +{
> +	int val;
> +	int att;
> +
> +	for (att = 0; att < s_retries; att++) {
> +		val = i2c_smbus_read_byte_data(lp->client, reg);
> +		if (val >= 0)
> +			return (u8)val;
> +	}
> +	return 0;
> +}
> +
> +static int arcxcnn_update_bit(struct arcxcnn *lp, u8 reg, u8 mask, u8 data)
> +{
> +	int ret, att;
> +	u8 tmp;
> +
> +	for (att = 0, ret = -1; att < s_retries; att++) {
> +		ret = i2c_smbus_read_byte_data(lp->client, reg);
> +		if (ret >= 0)
> +			break;
> +	}
> +	if (ret < 0) {
> +		dev_err(lp->dev, "failed to read 0x%.2x\n", reg);
> +		return ret;
> +	}
> +
> +	tmp = (u8)ret;
> +	tmp &= ~mask;
> +	tmp |= data & mask;
> +
> +	return arcxcnn_write_byte(lp, reg, tmp);
> +}

I'd really rather you didn't role your own read/write/update API!

> +static int arcxcnn_set_brightness(struct arcxcnn *lp, u32 brightness)
> +{
> +	int ret;
> +	u8 val;
> +
> +	val = (brightness & 0xF) << 4;

Define the shift value.

> +	ret = arcxcnn_write_byte(lp, ARCXCNN_WLED_ISET_LSB, val);
> +	if (ret < 0)
> +		return ret;
> +	val = (brightness >> 4);
> +	ret = arcxcnn_write_byte(lp, ARCXCNN_WLED_ISET_MSB, val);

'\n' here.

> +	return ret;
> +}
> +
> +static int arcxcnn_bl_update_status(struct backlight_device *bl)
> +{
> +	struct arcxcnn *lp = bl_get_data(bl);
> +	u32 brightness = bl->props.brightness;
> +
> +	if (bl->props.state & (BL_CORE_SUSPENDED | BL_CORE_FBBLANK))
> +		brightness = 0;
> +
> +	/* set brightness */
> +	if (lp->mode == PWM_BASED)
> +		; /* via pwm */

Replace this with a comment.

> +	else if (lp->mode == REGISTER_BASED)
> +		arcxcnn_set_brightness(lp, brightness);
> +
> +	/* set power-on/off/save modes */
> +	if (bl->props.power == 0)
> +		/* take out of standby */
> +		arcxcnn_update_bit(lp, ARCXCNN_CMD, ARCXCNN_CMD_STDBY, 0);
> +	else
> +		/* 1-3 == power save, 4 = off
> +		 * place in low-power standby mode
> +		 */

This is not a valid multi-line kernel comment.

See: Documentation/CodingStyle

> +		arcxcnn_update_bit(lp, ARCXCNN_CMD,
> +				ARCXCNN_CMD_STDBY, ARCXCNN_CMD_STDBY);
> +	return 0;
> +}
> +
> +static const struct backlight_ops arcxcnn_bl_ops = {
> +	.options = BL_CORE_SUSPENDRESUME,
> +	.update_status = arcxcnn_bl_update_status,
> +};
> +
> +static int arcxcnn_backlight_register(struct arcxcnn *lp)
> +{
> +	struct backlight_device *bl;

This variable seems pretty redundant.

> +	struct backlight_properties props;

Dynamically request memory for this.

> +	struct arcxcnn_platform_data *pdata = lp->pdata;
> +	const char *name = pdata->name ? : DEFAULT_BL_NAME;

Why do you need to set a name different from the device name?

> +	memset(&props, 0, sizeof(props));
> +	props.type = BACKLIGHT_PLATFORM;
> +	props.max_brightness = MAX_BRIGHTNESS;
> +
> +	if (pdata->initial_brightness > props.max_brightness)
> +		pdata->initial_brightness = props.max_brightness;
> +
> +	props.brightness = pdata->initial_brightness;
> +
> +	bl = devm_backlight_device_register(lp->dev, name, lp->dev, lp,
> +				       &arcxcnn_bl_ops, &props);
> +	if (IS_ERR(bl))
> +		return PTR_ERR(bl);
> +
> +	lp->bl = bl;
> +
> +	return 0;
> +}
> +
> +static ssize_t arcxcnn_get_chip_id(struct device *dev,

This should be arcxcnn_chip_id_show()

> +		struct device_attribute *attr, char *buf)
> +{
> +	struct arcxcnn *lp = dev_get_drvdata(dev);
> +
> +	return scnprintf(buf, PAGE_SIZE, "%s\n", lp->chipname);
> +}
> +
> +static ssize_t arcxcnn_get_led_str(struct device *dev,
> +		struct device_attribute *attr, char *buf)
> +{
> +	struct arcxcnn *lp = dev_get_drvdata(dev);
> +
> +	return scnprintf(buf, PAGE_SIZE, "%02X\n", lp->pdata->led_str);

This is not pdata.

What is led_str anyway?  It looks like an int, not a string.

> +}
> +
> +static ssize_t arcxcnn_set_led_str(struct device *dev,
> +		struct device_attribute *attr, const char *buf, size_t len)
> +{

arcxcnn_led_str_store()

> +	struct arcxcnn *lp = dev_get_drvdata(dev);
> +	unsigned long ledstr;
> +
> +	if (kstrtoul(buf, 0, &ledstr))
> +		return 0;
> +
> +	if (ledstr != lp->pdata->led_str) {
> +		/* don't allow 0 for ledstr, use power to turn all off */
> +		if (ledstr == 0)
> +			return 0;

Shouldn't you be return -EINVAL if 0 is not valid?

> +		lp->pdata->led_str = ledstr & 0x3F;
> +		arcxcnn_update_bit(lp, ARCXCNN_LEDEN,
> +			ARCXCNN_LEDEN_MASK, lp->pdata->led_str);

What are you lining up against here?

> +	}

'\n'

> +	return len;
> +}
> +
> +static ssize_t arcxcnn_get_bl_ctl_mode(struct device *dev,
> +	     struct device_attribute *attr, char *buf)
> +{

arcxcnn_bl_ctl_mode_show()

> +	struct arcxcnn *lp = dev_get_drvdata(dev);
> +	char *strmode = NULL;

Why are you pre-initialising here?

> +	if (lp->mode == PWM_BASED)
> +		strmode = "pwm based";
> +	else if (lp->mode == REGISTER_BASED)
> +		strmode = "register based";

Remove "based" and place it in scnprintf instead.

> +	return scnprintf(buf, PAGE_SIZE, "%s\n", strmode);
> +}
> +
> +static DEVICE_ATTR(chip_id, 0444, arcxcnn_get_chip_id, NULL);
> +static DEVICE_ATTR(led_str, 0664, arcxcnn_get_led_str, arcxcnn_set_led_str);
> +static DEVICE_ATTR(bl_ctl_mode, 0444, arcxcnn_get_bl_ctl_mode, NULL);
> +
> +static struct attribute *arcxcnn_attributes[] = {
> +	&dev_attr_chip_id.attr,
> +	&dev_attr_led_str.attr,
> +	&dev_attr_bl_ctl_mode.attr,
> +	NULL,
> +};
> +
> +static const struct attribute_group arcxcnn_attr_group = {
> +	.attrs = arcxcnn_attributes,
> +};
> +
> +#ifdef CONFIG_OF

No ifdefery please.

Use if (IS_ENABLED(CONFIG_OF)) before calling arcxcnn_parse_dt()
instead.

> +static int arcxcnn_parse_dt(struct arcxcnn *lp)
> +{
> +	struct device *dev = lp->dev;
> +	struct device_node *node = dev->of_node;
> +	u32 prog_val, num_entry, sources[6];
> +	int ret;
> +
> +	if (!node) {
> +		dev_err(dev, "no platform data.\n");

That's not what this means is it?

> +		return -EINVAL;
> +	}

'\n'

> +	lp->pdata->led_config_0_set = false;
> +	lp->pdata->led_config_1_set = false;
> +	lp->pdata->dim_freq_set = false;
> +	lp->pdata->comp_config_set = false;
> +	lp->pdata->filter_config_set = false;
> +	lp->pdata->trim_config_set = false;

These are already 0.

And you need to take these 'out' of pdata.

Create a config struct to place them all in and add it to ddata.

> +	ret = of_property_read_string(node, "label", &lp->pdata->name);
> +	if (ret < 0)
> +		lp->pdata->name = NULL;
> +
> +	ret = of_property_read_u32(node, "default-brightness", &prog_val);
> +	if (ret < 0)
> +		prog_val = s_ibright;
> +	lp->pdata->initial_brightness = prog_val;
> +	if (lp->pdata->initial_brightness > MAX_BRIGHTNESS)
> +		lp->pdata->initial_brightness = MAX_BRIGHTNESS;
> +
> +	ret = of_property_read_u32(node, "arc,led-config-0", &prog_val);
> +	if (ret == 0) {
> +		lp->pdata->led_config_0 = (u8)prog_val;
> +		lp->pdata->led_config_0_set = true;
> +	}
> +	ret = of_property_read_u32(node, "arc,led-config-1", &prog_val);
> +	if (ret == 0) {
> +		lp->pdata->led_config_1 = (u8)prog_val;
> +		lp->pdata->led_config_1_set = true;
> +	}
> +	ret = of_property_read_u32(node, "arc,dim-freq", &prog_val);
> +	if (ret == 0) {
> +		lp->pdata->dim_freq = (u8)prog_val;
> +		lp->pdata->dim_freq_set = true;
> +	}
> +	ret = of_property_read_u32(node, "arc,comp-config", &prog_val);
> +	if (ret == 0) {
> +		lp->pdata->comp_config = (u8)prog_val;
> +		lp->pdata->comp_config_set = true;
> +	}
> +	ret = of_property_read_u32(node, "arc,filter-config", &prog_val);
> +	if (ret == 0) {
> +		lp->pdata->filter_config = (u8)prog_val;
> +		lp->pdata->filter_config_set = true;
> +	}
> +	ret = of_property_read_u32(node, "arc,trim-config", &prog_val);
> +	if (ret == 0) {
> +		lp->pdata->trim_config = (u8)prog_val;
> +		lp->pdata->trim_config_set = true;
> +	}

You need to get these signed off by the DT folk.

> +	ret = of_property_count_u32_elems(node, "led-sources");
> +	if (ret < 0)
> +		lp->pdata->led_str = 0x3F;

What is 3F?  Please define it.

> +	else {
> +		num_entry = ret;
> +		if (num_entry > 6)
> +			num_entry = 6;

What is 6?  No magic numbers.

> +		ret = of_property_read_u32_array(node, "led-sources", sources,
> +					num_entry);
> +		if (ret < 0) {
> +			dev_err(dev, "led-sources node is invalid.\n");
> +			return -EINVAL;
> +		}
> +
> +		lp->pdata->led_str = 0;
> +		while (num_entry > 0)
> +			lp->pdata->led_str |= (1 << sources[--num_entry]);

This is not good code.  Please make it easier to read.

> +	}
> +	return 0;
> +}
> +#else
> +static int arcxcnn_parse_dt(struct arcxcnn *lp)
> +{
> +	return -EINVAL;
> +}
> +#endif
> +
> +static int arcxcnn_probe(struct i2c_client *cl, const struct i2c_device_id *id)
> +{
> +	struct arcxcnn *lp;
> +	int ret;
> +	u8 regval;
> +	u16 chipid;
> +
> +	if (!i2c_check_functionality(cl->adapter, I2C_FUNC_SMBUS_BYTE_DATA))
> +		return -EIO;
> +
> +	lp = devm_kzalloc(&cl->dev, sizeof(*lp), GFP_KERNEL);
> +	if (!lp)
> +		return -ENOMEM;
> +
> +	lp->client = cl;
> +	lp->dev = &cl->dev;

You don't need both of these.

> +	lp->chip_id = id->driver_data;

What are you going to use this for?

> +	lp->pdata = dev_get_platdata(&cl->dev);
> +
> +	if (!lp->pdata) {
> +		lp->pdata = devm_kzalloc(lp->dev,
> +				sizeof(*lp->pdata), GFP_KERNEL);
> +		if (!lp->pdata)
> +			return -ENOMEM;
> +
> +		/* no platform data, parse the device-tree for info.  if there
> +		 * is no device tree entry, we are being told we exist because
> +		 * user-land said so, so make up the info we need
> +		 */

Not a valid multi-line comment.

> +		ret = arcxcnn_parse_dt(lp);
> +		if (ret < 0) {
> +			/* no device tree, use defaults based on module params
> +			 */

Not a valid single-line comment.

> +			lp->pdata->led_config_0_set = false;
> +			lp->pdata->led_config_1_set = false;
> +			lp->pdata->dim_freq_set = false;
> +			lp->pdata->comp_config_set = false;
> +			lp->pdata->filter_config_set = false;
> +			lp->pdata->trim_config_set = false;
> +			lp->pdata->name = NULL;

These are already 0.

> +			lp->pdata->initial_brightness = s_ibright;
> +			lp->pdata->led_str = s_iledstr;
> +		}
> +	}
> +
> +	if (lp->pdata->dim_freq_set)
> +		lp->mode = PWM_BASED;
> +	else
> +		lp->mode = REGISTER_BASED;
> +
> +	i2c_set_clientdata(cl, lp);
> +
> +	/* read device ID */
> +	regval = arcxcnn_read_byte(lp, 0x1E);
> +	chipid = regval;
> +	chipid <<= 8;
> +	regval = arcxcnn_read_byte(lp, 0x1F);
> +	chipid |= regval;

Define all magic numbers.

> +	/* make sure it belongs to this driver
> +	 * TODO - handle specific ids
> +	 */
> +	if (chipid != 0x02A5) {
> +		#if 1

What on earth is this?

> +		dev_info(&cl->dev, "Chip Id is %04X\n", chipid);
> +		#else
> +		dev_err(&cl->dev, "%04X is not ARC2C\n", chipid);
> +		return -ENODEV;
> +		#endif
> +	}
> +	/* reset the device */
> +	arcxcnn_write_byte(lp, ARCXCNN_CMD, ARCXCNN_CMD_RESET);
> +
> +	/* set initial brightness */
> +	arcxcnn_set_brightness(lp, lp->pdata->initial_brightness);
> +
> +	/* if fadectrl set in DT, set the value directly, else leave default */
> +	if (lp->pdata->led_config_0_set)
> +		arcxcnn_write_byte(lp, ARCXCNN_FADECTRL,
> +			lp->pdata->led_config_0);
> +
> +	/* if iled config set in DT, set the value, else internal mode */

Spelling.

> +	if (lp->pdata->led_config_1_set)
> +		arcxcnn_write_byte(lp, ARCXCNN_ILED_CONFIG,
> +			lp->pdata->led_config_1);
> +	else
> +		arcxcnn_write_byte(lp, ARCXCNN_ILED_CONFIG, 0x57);

More magic numbers.

> +	/* other misc DT settings */
> +	if (lp->pdata->dim_freq_set)
> +		arcxcnn_write_byte(lp, ARCXCNN_FADECTRL, lp->pdata->dim_freq);
> +	if (lp->pdata->comp_config_set)
> +		arcxcnn_write_byte(lp, ARCXCNN_COMP_CONFIG,
> +			lp->pdata->comp_config);
> +	if (lp->pdata->filter_config_set)
> +		arcxcnn_write_byte(lp, ARCXCNN_FILT_CONFIG,
> +			lp->pdata->filter_config);
> +	if (lp->pdata->trim_config_set)
> +		arcxcnn_write_byte(lp, ARCXCNN_IMAXTUNE,
> +			lp->pdata->trim_config);

What are the default values of these registers?

If 0, then just write them without the checks.

> +	/* set initial LED Strings */

What is LED strings?

> +	arcxcnn_update_bit(lp, ARCXCNN_LEDEN,
> +		ARCXCNN_LEDEN_MASK, lp->pdata->led_str);
> +
> +	snprintf(lp->chipname, sizeof(lp->chipname),
> +		"%s-%04X", id->name, chipid);
> +
> +	ret = arcxcnn_backlight_register(lp);
> +	if (ret) {
> +		dev_err(lp->dev,
> +			"failed to register backlight. err: %d\n", ret);
> +		return ret;
> +	}
> +
> +	ret = sysfs_create_group(&lp->dev->kobj, &arcxcnn_attr_group);
> +	if (ret) {
> +		dev_err(lp->dev, "failed to register sysfs. err: %d\n", ret);
> +		return ret;
> +	}
> +
> +	backlight_update_status(lp->bl);

'\n'

> +	return 0;
> +}
> +
> +static int arcxcnn_remove(struct i2c_client *cl)
> +{
> +	struct arcxcnn *lp = i2c_get_clientdata(cl);
> +
> +	if (!s_no_reset_on_remove) {
> +		/* disable all strings */
> +		arcxcnn_write_byte(lp, ARCXCNN_LEDEN, 0x00);
> +		/* reset the device */
> +		arcxcnn_write_byte(lp, ARCXCNN_CMD, ARCXCNN_CMD_RESET);
> +	}

'\n'

> +	lp->bl->props.brightness = 0;

'\n'

> +	backlight_update_status(lp->bl);

'\n'

> +	if (lp->supply)
> +		regulator_disable(lp->supply);

'\n'

> +	sysfs_remove_group(&lp->dev->kobj, &arcxcnn_attr_group);
> +
> +	return 0;
> +}
> +
> +static const struct of_device_id arcxcnn_dt_ids[] = {
> +	{ .compatible = "arc,arc2c0608" },
> +	{ }
> +};
> +MODULE_DEVICE_TABLE(of, arcxcnn_dt_ids);
> +
> +/* Note that the device/chip ID is not fixed in silicon so
> + * auto-probing of these devices on the bus is most likely
> + * not possible, use device tree to set i2c bus address

Then why supply it here at all?

> + */
> +static const struct i2c_device_id arcxcnn_ids[] = {
> +	{"arc2c0608", ARC2C0608},
> +	{ }
> +};
> +MODULE_DEVICE_TABLE(i2c, arcxcnn_ids);
> +
> +static struct i2c_driver arcxcnn_driver = {
> +	.driver = {
> +		   .name = "arcxcnn_bl",
> +		   .of_match_table = of_match_ptr(arcxcnn_dt_ids),
> +		   },

Tabbing.

> +	.probe = arcxcnn_probe,
> +	.remove = arcxcnn_remove,
> +	.id_table = arcxcnn_ids,
> +};
> +

Superfluous '\n'

> +module_i2c_driver(arcxcnn_driver);
> +
> +MODULE_LICENSE("GPL v2");
> +MODULE_AUTHOR("Brian Dodge <bdodge09@outlook.com>");

Who?

> +MODULE_DESCRIPTION("ARCXCNN Backlight driver");
> diff --git a/include/linux/i2c/arcxcnn.h b/include/linux/i2c/arcxcnn.h
> new file mode 100644
> index 0000000..1c681dd
> --- /dev/null
> +++ b/include/linux/i2c/arcxcnn.h
> @@ -0,0 +1,67 @@
> +/*
> + * Backlight driver for ArcticSand ARC2C0608 Backlight Devices
> + *
> + * Copyright 2016 ArcticSand, Inc.
> + *
> + * Licensed under the GPL-2 or later.
> + */
> +
> +#ifndef _ARCXCNN_H
> +#define _ARCXCNN_H
> +
> +enum arcxcnn_chip_id {
> +	ARC2C0608
> +};
> +
> +enum arcxcnn_brightness_source {
> +	ARCXCNN_PWM_ONLY,
> +	ARCXCNN_I2C_ONLY = 2,
> +};
> +
> +#define ARCXCNN_MAX_PROGENTRIES	48	/* max a/v pairs for custom */
> +
> +/**
> + * struct arcxcnn_platform_data
> + * @name : Backlight driver name. If it is not defined, default name is set.
> + * @initial_brightness : initial value of backlight brightness
> + * @led_str	 : initial LED string enables, upper bit is global on/off
> + * @led_config_0 : fading speed (period between intensity steps)
> + * @led_config_1 : misc settings, see datasheet
> + * @dim_freq	 : pwm dimming frequency if in pwm mode
> + * @comp_config	 : misc config, see datasheet
> + * @filter_config: RC/PWM filter config, see datasheet
> + * @trim_config	 : full scale current trim, see datasheet
> + * @led_config_0_set	: the value in led_config_0 is valid
> + * @led_config_1_set	: the value in led_config_1 is valid
> + * @dim_freq_set	: the value in dim_freq is valid
> + * @comp_config_set	: the value in comp_config is valid
> + * @filter_config_set	: the value in filter_config is valid
> + * @trim_config_set	: the value in trim_config is valid

Tab out the ':'s.

This is only platform data if it's set by the platform.

Otherwise it's just a config or bitfields.

> + * the _set flags are used to indicate that the value was explicitly set
> + * in the device tree or platform data. settings not set are left as default
> + * power-on default values of the chip except for led_str and led_config_1
> + * which are set by the driver (led_str is specified indirectly in the
> + * device tree via "led-sources")
> + */
> +struct arcxcnn_platform_data {
> +	const char *name;
> +	u16 initial_brightness;
> +	u8	led_str;
> +
> +	u8	led_config_0;
> +	u8	led_config_1;
> +	u8	dim_freq;
> +	u8	comp_config;
> +	u8	filter_config;
> +	u8	trim_config;
> +
> +	bool	led_config_0_set;
> +	bool	led_config_1_set;
> +	bool	dim_freq_set;
> +	bool	comp_config_set;
> +	bool	filter_config_set;
> +	bool	trim_config_set;
> +};
> +
> +#endif

-- 
Lee Jones
Linaro STMicroelectronics Landing Team Lead
Linaro.org │ Open source software for ARM SoCs
Follow Linaro: Facebook | Twitter | Blog

[PATCH 1/2] backlight: arcxcnn: add support for ArticSand devices

[Olimpiu Dejeu]

Resubmition of arcxcnn backlight driver addressing the naming convention
 concerns raised by Rob H.

Signed-off-by: Olimpiu Dejeu <olimpiu@arcticsand.com>

---
 drivers/video/backlight/Kconfig      |   7 +
 drivers/video/backlight/Makefile     |   1 +
 drivers/video/backlight/arcxcnn_bl.c | 541 +++++++++++++++++++++++++++++++++++
 include/linux/i2c/arcxcnn.h          |  67 +++++
 4 files changed, 616 insertions(+)
 create mode 100644 drivers/video/backlight/arcxcnn_bl.c
 create mode 100644 include/linux/i2c/arcxcnn.h

diff --git a/drivers/video/backlight/Kconfig b/drivers/video/backlight/Kconfig
index 5ffa4b4..4e1d2ad 100644
--- a/drivers/video/backlight/Kconfig
+++ b/drivers/video/backlight/Kconfig
@@ -460,6 +460,13 @@ config BACKLIGHT_BD6107
 	help
 	  If you have a Rohm BD6107 say Y to enable the backlight driver.
 
+config BACKLIGHT_ARCXCNN
+	tristate "Backlight driver for the Arctic Sands ARCxCnnnn family"
+	depends on I2C
+	help
+	  If you have an ARCxCnnnn family backlight say Y to enable
+	  the backlight driver.
+
 endif # BACKLIGHT_CLASS_DEVICE
 
 endif # BACKLIGHT_LCD_SUPPORT
diff --git a/drivers/video/backlight/Makefile b/drivers/video/backlight/Makefile
index 16ec534..8905129 100644
--- a/drivers/video/backlight/Makefile
+++ b/drivers/video/backlight/Makefile
@@ -55,3 +55,4 @@ obj-$(CONFIG_BACKLIGHT_SKY81452)	+= sky81452-backlight.o
 obj-$(CONFIG_BACKLIGHT_TOSA)		+= tosa_bl.o
 obj-$(CONFIG_BACKLIGHT_TPS65217)	+= tps65217_bl.o
 obj-$(CONFIG_BACKLIGHT_WM831X)		+= wm831x_bl.o
+obj-$(CONFIG_BACKLIGHT_ARCXCNN) 	+= arcxcnn_bl.o
diff --git a/drivers/video/backlight/arcxcnn_bl.c b/drivers/video/backlight/arcxcnn_bl.c
new file mode 100644
index 0000000..1dad680
--- /dev/null
+++ b/drivers/video/backlight/arcxcnn_bl.c
@@ -0,0 +1,541 @@
+/*
+ * Backlight driver for ArcticSand ARC_X_C_0N_0N Devices
+ *
+ * Copyright 2016 ArcticSand, Inc.
+ *
+ * Licensed under the GPL-2 or later.
+ */
+
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/i2c.h>
+#include <linux/backlight.h>
+#include <linux/err.h>
+#include <linux/of.h>
+#include <linux/pwm.h>
+#include <linux/regulator/consumer.h>
+
+#include "linux/i2c/arcxcnn.h"
+
+#define ARCXCNN_CMD		(0x00)  /* Command Register */
+#define ARCXCNN_CMD_STDBY	(0x80)	/* I2C Standby */
+#define ARCXCNN_CMD_RESET	(0x40)	/* Reset */
+#define ARCXCNN_CMD_BOOST	(0x10)	/* Boost */
+#define ARCXCNN_CMD_OVP_MASK	(0x0C)	/* --- Over Voltage Threshold */
+#define ARCXCNN_CMD_OVP_XXV	(0x0C)	/* <rsvrd> Over Voltage Threshold */
+#define ARCXCNN_CMD_OVP_20V	(0x08)	/* 20v Over Voltage Threshold */
+#define ARCXCNN_CMD_OVP_24V	(0x04)	/* 24v Over Voltage Threshold */
+#define ARCXCNN_CMD_OVP_31V	(0x00)	/* 31.4v Over Voltage Threshold */
+#define ARCXCNN_CMD_EXT_COMP	(0x01)	/* part (0) or full (1) external comp */
+
+#define ARCXCNN_CONFIG	(0x01)  /* Configuration */
+#define ARCXCNN_STATUS1	(0x02)  /* Status 1 */
+#define ARCXCNN_STATUS2	(0x03)  /* Status 2 */
+#define ARCXCNN_FADECTRL	(0x04)  /* Fading Control */
+#define ARCXCNN_ILED_CONFIG	(0x05)  /* ILED Configuration */
+
+#define ARCXCNN_LEDEN		(0x06)  /* LED Enable Register */
+#define ARCXCNN_LEDEN_ISETEXT	(0x80)	/* Full-scale current set externally */
+#define ARCXCNN_LEDEN_MASK	(0x3F)	/* LED string enables */
+#define ARCXCNN_LEDEN_LED1	(0x01)
+#define ARCXCNN_LEDEN_LED2	(0x02)
+#define ARCXCNN_LEDEN_LED3	(0x04)
+#define ARCXCNN_LEDEN_LED4	(0x08)
+#define ARCXCNN_LEDEN_LED5	(0x10)
+#define ARCXCNN_LEDEN_LED6	(0x20)
+
+#define ARCXCNN_WLED_ISET_LSB	(0x07)  /* LED ISET LSB (in upper nibble) */
+#define ARCXCNN_WLED_ISET_MSB	(0x08)  /* LED ISET MSB (8 bits) */
+
+#define ARCXCNN_DIMFREQ		(0x09)
+#define ARCXCNN_COMP_CONFIG	(0x0A)
+#define ARCXCNN_FILT_CONFIG	(0x0B)
+#define ARCXCNN_IMAXTUNE	(0x0C)
+
+#define DEFAULT_BL_NAME		"arctic_bl"
+#define MAX_BRIGHTNESS		4095
+
+static int s_no_reset_on_remove;
+module_param_named(noreset, s_no_reset_on_remove, int, 0644);
+MODULE_PARM_DESC(noreset, "No reset on module removal");
+
+static int s_ibright = 60;
+module_param_named(ibright, s_ibright, int, 0644);
+MODULE_PARM_DESC(ibright, "Initial brightness (when no plat data)");
+
+static int s_iledstr = 0x3F;
+module_param_named(iledstr, s_iledstr, int, 0644);
+MODULE_PARM_DESC(iledstr, "Initial LED String (when no plat data)");
+
+static int s_retries = 2; /* 1 == only one try */
+module_param_named(retries, s_retries, int, 0644);
+MODULE_PARM_DESC(retries, "I2C retries attempted");
+
+enum arcxcnn_brightness_ctrl_mode {
+	PWM_BASED = 1,
+	REGISTER_BASED,
+};
+
+struct arcxcnn;
+
+struct arcxcnn {
+	char chipname[64];
+	enum arcxcnn_chip_id chip_id;
+	enum arcxcnn_brightness_ctrl_mode mode;
+	struct i2c_client *client;
+	struct backlight_device *bl;
+	struct device *dev;
+	struct arcxcnn_platform_data *pdata;
+	struct pwm_device *pwm;
+	struct regulator *supply;	/* regulator for VDD input */
+};
+
+static int arcxcnn_write_byte(struct arcxcnn *lp, u8 reg, u8 data)
+{
+	s32 ret = -1;
+	int att;
+
+	for (att = 0; att < s_retries; att++) {
+		ret = i2c_smbus_write_byte_data(lp->client, reg, data);
+		if (ret >= 0)
+			return 0;
+	}
+	return ret;
+}
+
+static u8 arcxcnn_read_byte(struct arcxcnn *lp, u8 reg)
+{
+	int val;
+	int att;
+
+	for (att = 0; att < s_retries; att++) {
+		val = i2c_smbus_read_byte_data(lp->client, reg);
+		if (val >= 0)
+			return (u8)val;
+	}
+	return 0;
+}
+
+static int arcxcnn_update_bit(struct arcxcnn *lp, u8 reg, u8 mask, u8 data)
+{
+	int ret, att;
+	u8 tmp;
+
+	for (att = 0, ret = -1; att < s_retries; att++) {
+		ret = i2c_smbus_read_byte_data(lp->client, reg);
+		if (ret >= 0)
+			break;
+	}
+	if (ret < 0) {
+		dev_err(lp->dev, "failed to read 0x%.2x\n", reg);
+		return ret;
+	}
+
+	tmp = (u8)ret;
+	tmp &= ~mask;
+	tmp |= data & mask;
+
+	return arcxcnn_write_byte(lp, reg, tmp);
+}
+
+static int arcxcnn_set_brightness(struct arcxcnn *lp, u32 brightness)
+{
+	int ret;
+	u8 val;
+
+	val = (brightness & 0xF) << 4;
+	ret = arcxcnn_write_byte(lp, ARCXCNN_WLED_ISET_LSB, val);
+	if (ret < 0)
+		return ret;
+	val = (brightness >> 4);
+	ret = arcxcnn_write_byte(lp, ARCXCNN_WLED_ISET_MSB, val);
+	return ret;
+}
+
+static int arcxcnn_bl_update_status(struct backlight_device *bl)
+{
+	struct arcxcnn *lp = bl_get_data(bl);
+	u32 brightness = bl->props.brightness;
+
+	if (bl->props.state & (BL_CORE_SUSPENDED | BL_CORE_FBBLANK))
+		brightness = 0;
+
+	/* set brightness */
+	if (lp->mode == PWM_BASED)
+		; /* via pwm */
+	else if (lp->mode == REGISTER_BASED)
+		arcxcnn_set_brightness(lp, brightness);
+
+	/* set power-on/off/save modes */
+	if (bl->props.power == 0)
+		/* take out of standby */
+		arcxcnn_update_bit(lp, ARCXCNN_CMD, ARCXCNN_CMD_STDBY, 0);
+	else
+		/* 1-3 == power save, 4 = off
+		 * place in low-power standby mode
+		 */
+		arcxcnn_update_bit(lp, ARCXCNN_CMD,
+				ARCXCNN_CMD_STDBY, ARCXCNN_CMD_STDBY);
+	return 0;
+}
+
+static const struct backlight_ops arcxcnn_bl_ops = {
+	.options = BL_CORE_SUSPENDRESUME,
+	.update_status = arcxcnn_bl_update_status,
+};
+
+static int arcxcnn_backlight_register(struct arcxcnn *lp)
+{
+	struct backlight_device *bl;
+	struct backlight_properties props;
+	struct arcxcnn_platform_data *pdata = lp->pdata;
+	const char *name = pdata->name ? : DEFAULT_BL_NAME;
+
+	memset(&props, 0, sizeof(props));
+	props.type = BACKLIGHT_PLATFORM;
+	props.max_brightness = MAX_BRIGHTNESS;
+
+	if (pdata->initial_brightness > props.max_brightness)
+		pdata->initial_brightness = props.max_brightness;
+
+	props.brightness = pdata->initial_brightness;
+
+	bl = devm_backlight_device_register(lp->dev, name, lp->dev, lp,
+				       &arcxcnn_bl_ops, &props);
+	if (IS_ERR(bl))
+		return PTR_ERR(bl);
+
+	lp->bl = bl;
+
+	return 0;
+}
+
+static ssize_t arcxcnn_get_chip_id(struct device *dev,
+		struct device_attribute *attr, char *buf)
+{
+	struct arcxcnn *lp = dev_get_drvdata(dev);
+
+	return scnprintf(buf, PAGE_SIZE, "%s\n", lp->chipname);
+}
+
+static ssize_t arcxcnn_get_led_str(struct device *dev,
+		struct device_attribute *attr, char *buf)
+{
+	struct arcxcnn *lp = dev_get_drvdata(dev);
+
+	return scnprintf(buf, PAGE_SIZE, "%02X\n", lp->pdata->led_str);
+}
+
+static ssize_t arcxcnn_set_led_str(struct device *dev,
+		struct device_attribute *attr, const char *buf, size_t len)
+{
+	struct arcxcnn *lp = dev_get_drvdata(dev);
+	unsigned long ledstr;
+
+	if (kstrtoul(buf, 0, &ledstr))
+		return 0;
+
+	if (ledstr != lp->pdata->led_str) {
+		/* don't allow 0 for ledstr, use power to turn all off */
+		if (ledstr == 0)
+			return 0;
+		lp->pdata->led_str = ledstr & 0x3F;
+		arcxcnn_update_bit(lp, ARCXCNN_LEDEN,
+			ARCXCNN_LEDEN_MASK, lp->pdata->led_str);
+	}
+	return len;
+}
+
+static ssize_t arcxcnn_get_bl_ctl_mode(struct device *dev,
+	     struct device_attribute *attr, char *buf)
+{
+	struct arcxcnn *lp = dev_get_drvdata(dev);
+	char *strmode = NULL;
+
+	if (lp->mode == PWM_BASED)
+		strmode = "pwm based";
+	else if (lp->mode == REGISTER_BASED)
+		strmode = "register based";
+
+	return scnprintf(buf, PAGE_SIZE, "%s\n", strmode);
+}
+
+static DEVICE_ATTR(chip_id, 0444, arcxcnn_get_chip_id, NULL);
+static DEVICE_ATTR(led_str, 0664, arcxcnn_get_led_str, arcxcnn_set_led_str);
+static DEVICE_ATTR(bl_ctl_mode, 0444, arcxcnn_get_bl_ctl_mode, NULL);
+
+static struct attribute *arcxcnn_attributes[] = {
+	&dev_attr_chip_id.attr,
+	&dev_attr_led_str.attr,
+	&dev_attr_bl_ctl_mode.attr,
+	NULL,
+};
+
+static const struct attribute_group arcxcnn_attr_group = {
+	.attrs = arcxcnn_attributes,
+};
+
+#ifdef CONFIG_OF
+static int arcxcnn_parse_dt(struct arcxcnn *lp)
+{
+	struct device *dev = lp->dev;
+	struct device_node *node = dev->of_node;
+	u32 prog_val, num_entry, sources[6];
+	int ret;
+
+	if (!node) {
+		dev_err(dev, "no platform data.\n");
+		return -EINVAL;
+	}
+	lp->pdata->led_config_0_set = false;
+	lp->pdata->led_config_1_set = false;
+	lp->pdata->dim_freq_set = false;
+	lp->pdata->comp_config_set = false;
+	lp->pdata->filter_config_set = false;
+	lp->pdata->trim_config_set = false;
+
+	ret = of_property_read_string(node, "label", &lp->pdata->name);
+	if (ret < 0)
+		lp->pdata->name = NULL;
+
+	ret = of_property_read_u32(node, "default-brightness", &prog_val);
+	if (ret < 0)
+		prog_val = s_ibright;
+	lp->pdata->initial_brightness = prog_val;
+	if (lp->pdata->initial_brightness > MAX_BRIGHTNESS)
+		lp->pdata->initial_brightness = MAX_BRIGHTNESS;
+
+	ret = of_property_read_u32(node, "arc,led-config-0", &prog_val);
+	if (ret == 0) {
+		lp->pdata->led_config_0 = (u8)prog_val;
+		lp->pdata->led_config_0_set = true;
+	}
+	ret = of_property_read_u32(node, "arc,led-config-1", &prog_val);
+	if (ret == 0) {
+		lp->pdata->led_config_1 = (u8)prog_val;
+		lp->pdata->led_config_1_set = true;
+	}
+	ret = of_property_read_u32(node, "arc,dim-freq", &prog_val);
+	if (ret == 0) {
+		lp->pdata->dim_freq = (u8)prog_val;
+		lp->pdata->dim_freq_set = true;
+	}
+	ret = of_property_read_u32(node, "arc,comp-config", &prog_val);
+	if (ret == 0) {
+		lp->pdata->comp_config = (u8)prog_val;
+		lp->pdata->comp_config_set = true;
+	}
+	ret = of_property_read_u32(node, "arc,filter-config", &prog_val);
+	if (ret == 0) {
+		lp->pdata->filter_config = (u8)prog_val;
+		lp->pdata->filter_config_set = true;
+	}
+	ret = of_property_read_u32(node, "arc,trim-config", &prog_val);
+	if (ret == 0) {
+		lp->pdata->trim_config = (u8)prog_val;
+		lp->pdata->trim_config_set = true;
+	}
+	ret = of_property_count_u32_elems(node, "led-sources");
+	if (ret < 0)
+		lp->pdata->led_str = 0x3F;
+	else {
+		num_entry = ret;
+		if (num_entry > 6)
+			num_entry = 6;
+
+		ret = of_property_read_u32_array(node, "led-sources", sources,
+					num_entry);
+		if (ret < 0) {
+			dev_err(dev, "led-sources node is invalid.\n");
+			return -EINVAL;
+		}
+
+		lp->pdata->led_str = 0;
+		while (num_entry > 0)
+			lp->pdata->led_str |= (1 << sources[--num_entry]);
+	}
+	return 0;
+}
+#else
+static int arcxcnn_parse_dt(struct arcxcnn *lp)
+{
+	return -EINVAL;
+}
+#endif
+
+static int arcxcnn_probe(struct i2c_client *cl, const struct i2c_device_id *id)
+{
+	struct arcxcnn *lp;
+	int ret;
+	u8 regval;
+	u16 chipid;
+
+	if (!i2c_check_functionality(cl->adapter, I2C_FUNC_SMBUS_BYTE_DATA))
+		return -EIO;
+
+	lp = devm_kzalloc(&cl->dev, sizeof(*lp), GFP_KERNEL);
+	if (!lp)
+		return -ENOMEM;
+
+	lp->client = cl;
+	lp->dev = &cl->dev;
+	lp->chip_id = id->driver_data;
+	lp->pdata = dev_get_platdata(&cl->dev);
+
+	if (!lp->pdata) {
+		lp->pdata = devm_kzalloc(lp->dev,
+				sizeof(*lp->pdata), GFP_KERNEL);
+		if (!lp->pdata)
+			return -ENOMEM;
+
+		/* no platform data, parse the device-tree for info.  if there
+		 * is no device tree entry, we are being told we exist because
+		 * user-land said so, so make up the info we need
+		 */
+		ret = arcxcnn_parse_dt(lp);
+		if (ret < 0) {
+			/* no device tree, use defaults based on module params
+			 */
+			lp->pdata->led_config_0_set = false;
+			lp->pdata->led_config_1_set = false;
+			lp->pdata->dim_freq_set = false;
+			lp->pdata->comp_config_set = false;
+			lp->pdata->filter_config_set = false;
+			lp->pdata->trim_config_set = false;
+
+			lp->pdata->name = NULL;
+			lp->pdata->initial_brightness = s_ibright;
+			lp->pdata->led_str = s_iledstr;
+		}
+	}
+
+	if (lp->pdata->dim_freq_set)
+		lp->mode = PWM_BASED;
+	else
+		lp->mode = REGISTER_BASED;
+
+	i2c_set_clientdata(cl, lp);
+
+	/* read device ID */
+	regval = arcxcnn_read_byte(lp, 0x1E);
+	chipid = regval;
+	chipid <<= 8;
+	regval = arcxcnn_read_byte(lp, 0x1F);
+	chipid |= regval;
+
+	/* make sure it belongs to this driver
+	 * TODO - handle specific ids
+	 */
+	if (chipid != 0x02A5) {
+		#if 1
+		dev_info(&cl->dev, "Chip Id is %04X\n", chipid);
+		#else
+		dev_err(&cl->dev, "%04X is not ARC2C\n", chipid);
+		return -ENODEV;
+		#endif
+	}
+	/* reset the device */
+	arcxcnn_write_byte(lp, ARCXCNN_CMD, ARCXCNN_CMD_RESET);
+
+	/* set initial brightness */
+	arcxcnn_set_brightness(lp, lp->pdata->initial_brightness);
+
+	/* if fadectrl set in DT, set the value directly, else leave default */
+	if (lp->pdata->led_config_0_set)
+		arcxcnn_write_byte(lp, ARCXCNN_FADECTRL,
+			lp->pdata->led_config_0);
+
+	/* if iled config set in DT, set the value, else internal mode */
+	if (lp->pdata->led_config_1_set)
+		arcxcnn_write_byte(lp, ARCXCNN_ILED_CONFIG,
+			lp->pdata->led_config_1);
+	else
+		arcxcnn_write_byte(lp, ARCXCNN_ILED_CONFIG, 0x57);
+
+	/* other misc DT settings */
+	if (lp->pdata->dim_freq_set)
+		arcxcnn_write_byte(lp, ARCXCNN_FADECTRL, lp->pdata->dim_freq);
+	if (lp->pdata->comp_config_set)
+		arcxcnn_write_byte(lp, ARCXCNN_COMP_CONFIG,
+			lp->pdata->comp_config);
+	if (lp->pdata->filter_config_set)
+		arcxcnn_write_byte(lp, ARCXCNN_FILT_CONFIG,
+			lp->pdata->filter_config);
+	if (lp->pdata->trim_config_set)
+		arcxcnn_write_byte(lp, ARCXCNN_IMAXTUNE,
+			lp->pdata->trim_config);
+
+	/* set initial LED Strings */
+	arcxcnn_update_bit(lp, ARCXCNN_LEDEN,
+		ARCXCNN_LEDEN_MASK, lp->pdata->led_str);
+
+	snprintf(lp->chipname, sizeof(lp->chipname),
+		"%s-%04X", id->name, chipid);
+
+	ret = arcxcnn_backlight_register(lp);
+	if (ret) {
+		dev_err(lp->dev,
+			"failed to register backlight. err: %d\n", ret);
+		return ret;
+	}
+
+	ret = sysfs_create_group(&lp->dev->kobj, &arcxcnn_attr_group);
+	if (ret) {
+		dev_err(lp->dev, "failed to register sysfs. err: %d\n", ret);
+		return ret;
+	}
+
+	backlight_update_status(lp->bl);
+	return 0;
+}
+
+static int arcxcnn_remove(struct i2c_client *cl)
+{
+	struct arcxcnn *lp = i2c_get_clientdata(cl);
+
+	if (!s_no_reset_on_remove) {
+		/* disable all strings */
+		arcxcnn_write_byte(lp, ARCXCNN_LEDEN, 0x00);
+		/* reset the device */
+		arcxcnn_write_byte(lp, ARCXCNN_CMD, ARCXCNN_CMD_RESET);
+	}
+	lp->bl->props.brightness = 0;
+	backlight_update_status(lp->bl);
+	if (lp->supply)
+		regulator_disable(lp->supply);
+	sysfs_remove_group(&lp->dev->kobj, &arcxcnn_attr_group);
+
+	return 0;
+}
+
+static const struct of_device_id arcxcnn_dt_ids[] = {
+	{ .compatible = "arc,arc2c0608" },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, arcxcnn_dt_ids);
+
+/* Note that the device/chip ID is not fixed in silicon so
+ * auto-probing of these devices on the bus is most likely
+ * not possible, use device tree to set i2c bus address
+ */
+static const struct i2c_device_id arcxcnn_ids[] = {
+	{"arc2c0608", ARC2C0608},
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, arcxcnn_ids);
+
+static struct i2c_driver arcxcnn_driver = {
+	.driver = {
+		   .name = "arcxcnn_bl",
+		   .of_match_table = of_match_ptr(arcxcnn_dt_ids),
+		   },
+	.probe = arcxcnn_probe,
+	.remove = arcxcnn_remove,
+	.id_table = arcxcnn_ids,
+};
+
+module_i2c_driver(arcxcnn_driver);
+
+MODULE_LICENSE("GPL v2");
+MODULE_AUTHOR("Brian Dodge <bdodge09@outlook.com>");
+MODULE_DESCRIPTION("ARCXCNN Backlight driver");
diff --git a/include/linux/i2c/arcxcnn.h b/include/linux/i2c/arcxcnn.h
new file mode 100644
index 0000000..1c681dd
--- /dev/null
+++ b/include/linux/i2c/arcxcnn.h
@@ -0,0 +1,67 @@
+/*
+ * Backlight driver for ArcticSand ARC2C0608 Backlight Devices
+ *
+ * Copyright 2016 ArcticSand, Inc.
+ *
+ * Licensed under the GPL-2 or later.
+ */
+
+#ifndef _ARCXCNN_H
+#define _ARCXCNN_H
+
+enum arcxcnn_chip_id {
+	ARC2C0608
+};
+
+enum arcxcnn_brightness_source {
+	ARCXCNN_PWM_ONLY,
+	ARCXCNN_I2C_ONLY = 2,
+};
+
+#define ARCXCNN_MAX_PROGENTRIES	48	/* max a/v pairs for custom */
+
+/**
+ * struct arcxcnn_platform_data
+ * @name : Backlight driver name. If it is not defined, default name is set.
+ * @initial_brightness : initial value of backlight brightness
+ * @led_str	 : initial LED string enables, upper bit is global on/off
+ * @led_config_0 : fading speed (period between intensity steps)
+ * @led_config_1 : misc settings, see datasheet
+ * @dim_freq	 : pwm dimming frequency if in pwm mode
+ * @comp_config	 : misc config, see datasheet
+ * @filter_config: RC/PWM filter config, see datasheet
+ * @trim_config	 : full scale current trim, see datasheet
+ * @led_config_0_set	: the value in led_config_0 is valid
+ * @led_config_1_set	: the value in led_config_1 is valid
+ * @dim_freq_set	: the value in dim_freq is valid
+ * @comp_config_set	: the value in comp_config is valid
+ * @filter_config_set	: the value in filter_config is valid
+ * @trim_config_set	: the value in trim_config is valid
+ *
+ * the _set flags are used to indicate that the value was explicitly set
+ * in the device tree or platform data. settings not set are left as default
+ * power-on default values of the chip except for led_str and led_config_1
+ * which are set by the driver (led_str is specified indirectly in the
+ * device tree via "led-sources")
+ */
+struct arcxcnn_platform_data {
+	const char *name;
+	u16 initial_brightness;
+	u8	led_str;
+
+	u8	led_config_0;
+	u8	led_config_1;
+	u8	dim_freq;
+	u8	comp_config;
+	u8	filter_config;
+	u8	trim_config;
+
+	bool	led_config_0_set;
+	bool	led_config_1_set;
+	bool	dim_freq_set;
+	bool	comp_config_set;
+	bool	filter_config_set;
+	bool	trim_config_set;
+};
+
+#endif
-- 
2.7.4

Re: [PATCH 1/2] backlight: arcxcnn: add support for ArticSand devices

[Lee Jones]

On Wed, 09 Nov 2016, Lee Jones wrote:

> Jingoo?

Ah, it looks like you used the wrong address.

I should have been: jingoohan1@gmail.com

I'll CC him from here.

> On Wed, 26 Oct 2016, Olimpiu Dejeu wrote:
> 
> > Resubmition of arcxcnn backliught driver adding devicetree entries
> >  for all registers
> > 
> > Signed-off-by: Olimpiu Dejeu <olimpiu@arcticsand.com>
> > 
> > ---
> >  drivers/video/backlight/Kconfig      |   7 +
> >  drivers/video/backlight/Makefile     |   1 +
> >  drivers/video/backlight/arcxcnn_bl.c | 541 +++++++++++++++++++++++++++++++++++
> >  include/linux/i2c/arcxcnn.h          |  67 +++++
> >  4 files changed, 616 insertions(+)
> >  create mode 100644 drivers/video/backlight/arcxcnn_bl.c
> >  create mode 100644 include/linux/i2c/arcxcnn.h
> > 
> > diff --git a/drivers/video/backlight/Kconfig b/drivers/video/backlight/Kconfig
> > index 5ffa4b4..4e1d2ad 100644
> > --- a/drivers/video/backlight/Kconfig
> > +++ b/drivers/video/backlight/Kconfig
> > @@ -460,6 +460,13 @@ config BACKLIGHT_BD6107
> >  	help
> >  	  If you have a Rohm BD6107 say Y to enable the backlight driver.
> >  
> > +config BACKLIGHT_ARCXCNN
> > +	tristate "Backlight driver for the Arctic Sands ARCxCnnnn family"
> > +	depends on I2C
> > +	help
> > +	  If you have an ARCxCnnnn family backlight say Y to enable
> > +	  the backlight driver.
> > +
> >  endif # BACKLIGHT_CLASS_DEVICE
> >  
> >  endif # BACKLIGHT_LCD_SUPPORT
> > diff --git a/drivers/video/backlight/Makefile b/drivers/video/backlight/Makefile
> > index 16ec534..8905129 100644
> > --- a/drivers/video/backlight/Makefile
> > +++ b/drivers/video/backlight/Makefile
> > @@ -55,3 +55,4 @@ obj-$(CONFIG_BACKLIGHT_SKY81452)	+= sky81452-backlight.o
> >  obj-$(CONFIG_BACKLIGHT_TOSA)		+= tosa_bl.o
> >  obj-$(CONFIG_BACKLIGHT_TPS65217)	+= tps65217_bl.o
> >  obj-$(CONFIG_BACKLIGHT_WM831X)		+= wm831x_bl.o
> > +obj-$(CONFIG_BACKLIGHT_ARCXCNN) 	+= arcxcnn_bl.o
> > diff --git a/drivers/video/backlight/arcxcnn_bl.c b/drivers/video/backlight/arcxcnn_bl.c
> > new file mode 100644
> > index 0000000..1dad680
> > --- /dev/null
> > +++ b/drivers/video/backlight/arcxcnn_bl.c
> > @@ -0,0 +1,541 @@
> > +/*
> > + * Backlight driver for ArcticSand ARC_X_C_0N_0N Devices
> > + *
> > + * Copyright 2016 ArcticSand, Inc.
> > + *
> > + * Licensed under the GPL-2 or later.
> > + */
> > +
> > +#include <linux/module.h>
> > +#include <linux/slab.h>
> > +#include <linux/i2c.h>
> > +#include <linux/backlight.h>
> > +#include <linux/err.h>
> > +#include <linux/of.h>
> > +#include <linux/pwm.h>
> > +#include <linux/regulator/consumer.h>
> > +
> > +#include "linux/i2c/arcxcnn.h"
> > +
> > +#define ARCXCNN_CMD		(0x00)  /* Command Register */
> > +#define ARCXCNN_CMD_STDBY	(0x80)	/* I2C Standby */
> > +#define ARCXCNN_CMD_RESET	(0x40)	/* Reset */
> > +#define ARCXCNN_CMD_BOOST	(0x10)	/* Boost */
> > +#define ARCXCNN_CMD_OVP_MASK	(0x0C)	/* --- Over Voltage Threshold */
> > +#define ARCXCNN_CMD_OVP_XXV	(0x0C)	/* <rsvrd> Over Voltage Threshold */
> > +#define ARCXCNN_CMD_OVP_20V	(0x08)	/* 20v Over Voltage Threshold */
> > +#define ARCXCNN_CMD_OVP_24V	(0x04)	/* 24v Over Voltage Threshold */
> > +#define ARCXCNN_CMD_OVP_31V	(0x00)	/* 31.4v Over Voltage Threshold */
> > +#define ARCXCNN_CMD_EXT_COMP	(0x01)	/* part (0) or full (1) external comp */
> > +
> > +#define ARCXCNN_CONFIG	(0x01)  /* Configuration */
> > +#define ARCXCNN_STATUS1	(0x02)  /* Status 1 */
> > +#define ARCXCNN_STATUS2	(0x03)  /* Status 2 */
> > +#define ARCXCNN_FADECTRL	(0x04)  /* Fading Control */
> > +#define ARCXCNN_ILED_CONFIG	(0x05)  /* ILED Configuration */
> > +
> > +#define ARCXCNN_LEDEN		(0x06)  /* LED Enable Register */
> > +#define ARCXCNN_LEDEN_ISETEXT	(0x80)	/* Full-scale current set externally */
> > +#define ARCXCNN_LEDEN_MASK	(0x3F)	/* LED string enables */
> > +#define ARCXCNN_LEDEN_LED1	(0x01)
> > +#define ARCXCNN_LEDEN_LED2	(0x02)
> > +#define ARCXCNN_LEDEN_LED3	(0x04)
> > +#define ARCXCNN_LEDEN_LED4	(0x08)
> > +#define ARCXCNN_LEDEN_LED5	(0x10)
> > +#define ARCXCNN_LEDEN_LED6	(0x20)
> > +
> > +#define ARCXCNN_WLED_ISET_LSB	(0x07)  /* LED ISET LSB (in upper nibble) */
> > +#define ARCXCNN_WLED_ISET_MSB	(0x08)  /* LED ISET MSB (8 bits) */
> > +
> > +#define ARCXCNN_DIMFREQ		(0x09)
> > +#define ARCXCNN_COMP_CONFIG	(0x0A)
> > +#define ARCXCNN_FILT_CONFIG	(0x0B)
> > +#define ARCXCNN_IMAXTUNE	(0x0C)
> > +
> > +#define DEFAULT_BL_NAME		"arctic_bl"
> > +#define MAX_BRIGHTNESS		4095
> > +
> > +static int s_no_reset_on_remove;
> > +module_param_named(noreset, s_no_reset_on_remove, int, 0644);
> > +MODULE_PARM_DESC(noreset, "No reset on module removal");
> > +
> > +static int s_ibright = 60;
> > +module_param_named(ibright, s_ibright, int, 0644);
> > +MODULE_PARM_DESC(ibright, "Initial brightness (when no plat data)");
> > +
> > +static int s_iledstr = 0x3F;
> > +module_param_named(iledstr, s_iledstr, int, 0644);
> > +MODULE_PARM_DESC(iledstr, "Initial LED String (when no plat data)");
> > +
> > +static int s_retries = 2; /* 1 == only one try */
> > +module_param_named(retries, s_retries, int, 0644);
> > +MODULE_PARM_DESC(retries, "I2C retries attempted");
> > +
> > +enum arcxcnn_brightness_ctrl_mode {
> > +	PWM_BASED = 1,
> > +	REGISTER_BASED,
> > +};
> > +
> > +struct arcxcnn;
> > +
> > +struct arcxcnn {
> > +	char chipname[64];
> > +	enum arcxcnn_chip_id chip_id;
> > +	enum arcxcnn_brightness_ctrl_mode mode;
> > +	struct i2c_client *client;
> > +	struct backlight_device *bl;
> > +	struct device *dev;
> > +	struct arcxcnn_platform_data *pdata;
> > +	struct pwm_device *pwm;
> > +	struct regulator *supply;	/* regulator for VDD input */
> > +};
> > +
> > +static int arcxcnn_write_byte(struct arcxcnn *lp, u8 reg, u8 data)
> > +{
> > +	s32 ret = -1;
> > +	int att;
> > +
> > +	for (att = 0; att < s_retries; att++) {
> > +		ret = i2c_smbus_write_byte_data(lp->client, reg, data);
> > +		if (ret >= 0)
> > +			return 0;
> > +	}
> > +	return ret;
> > +}
> > +
> > +static u8 arcxcnn_read_byte(struct arcxcnn *lp, u8 reg)
> > +{
> > +	int val;
> > +	int att;
> > +
> > +	for (att = 0; att < s_retries; att++) {
> > +		val = i2c_smbus_read_byte_data(lp->client, reg);
> > +		if (val >= 0)
> > +			return (u8)val;
> > +	}
> > +	return 0;
> > +}
> > +
> > +static int arcxcnn_update_bit(struct arcxcnn *lp, u8 reg, u8 mask, u8 data)
> > +{
> > +	int ret, att;
> > +	u8 tmp;
> > +
> > +	for (att = 0, ret = -1; att < s_retries; att++) {
> > +		ret = i2c_smbus_read_byte_data(lp->client, reg);
> > +		if (ret >= 0)
> > +			break;
> > +	}
> > +	if (ret < 0) {
> > +		dev_err(lp->dev, "failed to read 0x%.2x\n", reg);
> > +		return ret;
> > +	}
> > +
> > +	tmp = (u8)ret;
> > +	tmp &= ~mask;
> > +	tmp |= data & mask;
> > +
> > +	return arcxcnn_write_byte(lp, reg, tmp);
> > +}
> > +
> > +static int arcxcnn_set_brightness(struct arcxcnn *lp, u32 brightness)
> > +{
> > +	int ret;
> > +	u8 val;
> > +
> > +	val = (brightness & 0xF) << 4;
> > +	ret = arcxcnn_write_byte(lp, ARCXCNN_WLED_ISET_LSB, val);
> > +	if (ret < 0)
> > +		return ret;
> > +	val = (brightness >> 4);
> > +	ret = arcxcnn_write_byte(lp, ARCXCNN_WLED_ISET_MSB, val);
> > +	return ret;
> > +}
> > +
> > +static int arcxcnn_bl_update_status(struct backlight_device *bl)
> > +{
> > +	struct arcxcnn *lp = bl_get_data(bl);
> > +	u32 brightness = bl->props.brightness;
> > +
> > +	if (bl->props.state & (BL_CORE_SUSPENDED | BL_CORE_FBBLANK))
> > +		brightness = 0;
> > +
> > +	/* set brightness */
> > +	if (lp->mode == PWM_BASED)
> > +		; /* via pwm */
> > +	else if (lp->mode == REGISTER_BASED)
> > +		arcxcnn_set_brightness(lp, brightness);
> > +
> > +	/* set power-on/off/save modes */
> > +	if (bl->props.power == 0)
> > +		/* take out of standby */
> > +		arcxcnn_update_bit(lp, ARCXCNN_CMD, ARCXCNN_CMD_STDBY, 0);
> > +	else
> > +		/* 1-3 == power save, 4 = off
> > +		 * place in low-power standby mode
> > +		 */
> > +		arcxcnn_update_bit(lp, ARCXCNN_CMD,
> > +				ARCXCNN_CMD_STDBY, ARCXCNN_CMD_STDBY);
> > +	return 0;
> > +}
> > +
> > +static const struct backlight_ops arcxcnn_bl_ops = {
> > +	.options = BL_CORE_SUSPENDRESUME,
> > +	.update_status = arcxcnn_bl_update_status,
> > +};
> > +
> > +static int arcxcnn_backlight_register(struct arcxcnn *lp)
> > +{
> > +	struct backlight_device *bl;
> > +	struct backlight_properties props;
> > +	struct arcxcnn_platform_data *pdata = lp->pdata;
> > +	const char *name = pdata->name ? : DEFAULT_BL_NAME;
> > +
> > +	memset(&props, 0, sizeof(props));
> > +	props.type = BACKLIGHT_PLATFORM;
> > +	props.max_brightness = MAX_BRIGHTNESS;
> > +
> > +	if (pdata->initial_brightness > props.max_brightness)
> > +		pdata->initial_brightness = props.max_brightness;
> > +
> > +	props.brightness = pdata->initial_brightness;
> > +
> > +	bl = devm_backlight_device_register(lp->dev, name, lp->dev, lp,
> > +				       &arcxcnn_bl_ops, &props);
> > +	if (IS_ERR(bl))
> > +		return PTR_ERR(bl);
> > +
> > +	lp->bl = bl;
> > +
> > +	return 0;
> > +}
> > +
> > +static ssize_t arcxcnn_get_chip_id(struct device *dev,
> > +		struct device_attribute *attr, char *buf)
> > +{
> > +	struct arcxcnn *lp = dev_get_drvdata(dev);
> > +
> > +	return scnprintf(buf, PAGE_SIZE, "%s\n", lp->chipname);
> > +}
> > +
> > +static ssize_t arcxcnn_get_led_str(struct device *dev,
> > +		struct device_attribute *attr, char *buf)
> > +{
> > +	struct arcxcnn *lp = dev_get_drvdata(dev);
> > +
> > +	return scnprintf(buf, PAGE_SIZE, "%02X\n", lp->pdata->led_str);
> > +}
> > +
> > +static ssize_t arcxcnn_set_led_str(struct device *dev,
> > +		struct device_attribute *attr, const char *buf, size_t len)
> > +{
> > +	struct arcxcnn *lp = dev_get_drvdata(dev);
> > +	unsigned long ledstr;
> > +
> > +	if (kstrtoul(buf, 0, &ledstr))
> > +		return 0;
> > +
> > +	if (ledstr != lp->pdata->led_str) {
> > +		/* don't allow 0 for ledstr, use power to turn all off */
> > +		if (ledstr == 0)
> > +			return 0;
> > +		lp->pdata->led_str = ledstr & 0x3F;
> > +		arcxcnn_update_bit(lp, ARCXCNN_LEDEN,
> > +			ARCXCNN_LEDEN_MASK, lp->pdata->led_str);
> > +	}
> > +	return len;
> > +}
> > +
> > +static ssize_t arcxcnn_get_bl_ctl_mode(struct device *dev,
> > +	     struct device_attribute *attr, char *buf)
> > +{
> > +	struct arcxcnn *lp = dev_get_drvdata(dev);
> > +	char *strmode = NULL;
> > +
> > +	if (lp->mode == PWM_BASED)
> > +		strmode = "pwm based";
> > +	else if (lp->mode == REGISTER_BASED)
> > +		strmode = "register based";
> > +
> > +	return scnprintf(buf, PAGE_SIZE, "%s\n", strmode);
> > +}
> > +
> > +static DEVICE_ATTR(chip_id, 0444, arcxcnn_get_chip_id, NULL);
> > +static DEVICE_ATTR(led_str, 0664, arcxcnn_get_led_str, arcxcnn_set_led_str);
> > +static DEVICE_ATTR(bl_ctl_mode, 0444, arcxcnn_get_bl_ctl_mode, NULL);
> > +
> > +static struct attribute *arcxcnn_attributes[] = {
> > +	&dev_attr_chip_id.attr,
> > +	&dev_attr_led_str.attr,
> > +	&dev_attr_bl_ctl_mode.attr,
> > +	NULL,
> > +};
> > +
> > +static const struct attribute_group arcxcnn_attr_group = {
> > +	.attrs = arcxcnn_attributes,
> > +};
> > +
> > +#ifdef CONFIG_OF
> > +static int arcxcnn_parse_dt(struct arcxcnn *lp)
> > +{
> > +	struct device *dev = lp->dev;
> > +	struct device_node *node = dev->of_node;
> > +	u32 prog_val, num_entry, sources[6];
> > +	int ret;
> > +
> > +	if (!node) {
> > +		dev_err(dev, "no platform data.\n");
> > +		return -EINVAL;
> > +	}
> > +	lp->pdata->led_config_0_set = false;
> > +	lp->pdata->led_config_1_set = false;
> > +	lp->pdata->dim_freq_set = false;
> > +	lp->pdata->comp_config_set = false;
> > +	lp->pdata->filter_config_set = false;
> > +	lp->pdata->trim_config_set = false;
> > +
> > +	ret = of_property_read_string(node, "label", &lp->pdata->name);
> > +	if (ret < 0)
> > +		lp->pdata->name = NULL;
> > +
> > +	ret = of_property_read_u32(node, "default-brightness", &prog_val);
> > +	if (ret < 0)
> > +		prog_val = s_ibright;
> > +	lp->pdata->initial_brightness = prog_val;
> > +	if (lp->pdata->initial_brightness > MAX_BRIGHTNESS)
> > +		lp->pdata->initial_brightness = MAX_BRIGHTNESS;
> > +
> > +	ret = of_property_read_u32(node, "arcticsand,led-config-0", &prog_val);
> > +	if (ret == 0) {
> > +		lp->pdata->led_config_0 = (u8)prog_val;
> > +		lp->pdata->led_config_0_set = true;
> > +	}
> > +	ret = of_property_read_u32(node, "arcticsand,led-config-1", &prog_val);
> > +	if (ret == 0) {
> > +		lp->pdata->led_config_1 = (u8)prog_val;
> > +		lp->pdata->led_config_1_set = true;
> > +	}
> > +	ret = of_property_read_u32(node, "arcticsand,dim-freq", &prog_val);
> > +	if (ret == 0) {
> > +		lp->pdata->dim_freq = (u8)prog_val;
> > +		lp->pdata->dim_freq_set = true;
> > +	}
> > +	ret = of_property_read_u32(node, "arcticsand,comp-config", &prog_val);
> > +	if (ret == 0) {
> > +		lp->pdata->comp_config = (u8)prog_val;
> > +		lp->pdata->comp_config_set = true;
> > +	}
> > +	ret = of_property_read_u32(node, "arcticsand,filter-config", &prog_val);
> > +	if (ret == 0) {
> > +		lp->pdata->filter_config = (u8)prog_val;
> > +		lp->pdata->filter_config_set = true;
> > +	}
> > +	ret = of_property_read_u32(node, "arcticsand,trim-config", &prog_val);
> > +	if (ret == 0) {
> > +		lp->pdata->trim_config = (u8)prog_val;
> > +		lp->pdata->trim_config_set = true;
> > +	}
> > +	ret = of_property_count_u32_elems(node, "led-sources");
> > +	if (ret < 0)
> > +		lp->pdata->led_str = 0x3F;
> > +	else {
> > +		num_entry = ret;
> > +		if (num_entry > 6)
> > +			num_entry = 6;
> > +
> > +		ret = of_property_read_u32_array(node, "led-sources", sources,
> > +					num_entry);
> > +		if (ret < 0) {
> > +			dev_err(dev, "led-sources node is invalid.\n");
> > +			return -EINVAL;
> > +		}
> > +
> > +		lp->pdata->led_str = 0;
> > +		while (num_entry > 0)
> > +			lp->pdata->led_str |= (1 << sources[--num_entry]);
> > +	}
> > +	return 0;
> > +}
> > +#else
> > +static int arcxcnn_parse_dt(struct arcxcnn *lp)
> > +{
> > +	return -EINVAL;
> > +}
> > +#endif
> > +
> > +static int arcxcnn_probe(struct i2c_client *cl, const struct i2c_device_id *id)
> > +{
> > +	struct arcxcnn *lp;
> > +	int ret;
> > +	u8 regval;
> > +	u16 chipid;
> > +
> > +	if (!i2c_check_functionality(cl->adapter, I2C_FUNC_SMBUS_BYTE_DATA))
> > +		return -EIO;
> > +
> > +	lp = devm_kzalloc(&cl->dev, sizeof(*lp), GFP_KERNEL);
> > +	if (!lp)
> > +		return -ENOMEM;
> > +
> > +	lp->client = cl;
> > +	lp->dev = &cl->dev;
> > +	lp->chip_id = id->driver_data;
> > +	lp->pdata = dev_get_platdata(&cl->dev);
> > +
> > +	if (!lp->pdata) {
> > +		lp->pdata = devm_kzalloc(lp->dev,
> > +				sizeof(*lp->pdata), GFP_KERNEL);
> > +		if (!lp->pdata)
> > +			return -ENOMEM;
> > +
> > +		/* no platform data, parse the device-tree for info.  if there
> > +		 * is no device tree entry, we are being told we exist because
> > +		 * user-land said so, so make up the info we need
> > +		 */
> > +		ret = arcxcnn_parse_dt(lp);
> > +		if (ret < 0) {
> > +			/* no device tree, use defaults based on module params
> > +			 */
> > +			lp->pdata->led_config_0_set = false;
> > +			lp->pdata->led_config_1_set = false;
> > +			lp->pdata->dim_freq_set = false;
> > +			lp->pdata->comp_config_set = false;
> > +			lp->pdata->filter_config_set = false;
> > +			lp->pdata->trim_config_set = false;
> > +
> > +			lp->pdata->name = NULL;
> > +			lp->pdata->initial_brightness = s_ibright;
> > +			lp->pdata->led_str = s_iledstr;
> > +		}
> > +	}
> > +
> > +	if (lp->pdata->dim_freq_set)
> > +		lp->mode = PWM_BASED;
> > +	else
> > +		lp->mode = REGISTER_BASED;
> > +
> > +	i2c_set_clientdata(cl, lp);
> > +
> > +	/* read device ID */
> > +	regval = arcxcnn_read_byte(lp, 0x1E);
> > +	chipid = regval;
> > +	chipid <<= 8;
> > +	regval = arcxcnn_read_byte(lp, 0x1F);
> > +	chipid |= regval;
> > +
> > +	/* make sure it belongs to this driver
> > +	 * TODO - handle specific ids
> > +	 */
> > +	if (chipid != 0x02A5) {
> > +		#if 1
> > +		dev_info(&cl->dev, "Chip Id is %04X\n", chipid);
> > +		#else
> > +		dev_err(&cl->dev, "%04X is not ARC2C\n", chipid);
> > +		return -ENODEV;
> > +		#endif
> > +	}
> > +	/* reset the device */
> > +	arcxcnn_write_byte(lp, ARCXCNN_CMD, ARCXCNN_CMD_RESET);
> > +
> > +	/* set initial brightness */
> > +	arcxcnn_set_brightness(lp, lp->pdata->initial_brightness);
> > +
> > +	/* if fadectrl set in DT, set the value directly, else leave default */
> > +	if (lp->pdata->led_config_0_set)
> > +		arcxcnn_write_byte(lp, ARCXCNN_FADECTRL,
> > +			lp->pdata->led_config_0);
> > +
> > +	/* if iled config set in DT, set the value, else internal mode */
> > +	if (lp->pdata->led_config_1_set)
> > +		arcxcnn_write_byte(lp, ARCXCNN_ILED_CONFIG,
> > +			lp->pdata->led_config_1);
> > +	else
> > +		arcxcnn_write_byte(lp, ARCXCNN_ILED_CONFIG, 0x57);
> > +
> > +	/* other misc DT settings */
> > +	if (lp->pdata->dim_freq_set)
> > +		arcxcnn_write_byte(lp, ARCXCNN_FADECTRL, lp->pdata->dim_freq);
> > +	if (lp->pdata->comp_config_set)
> > +		arcxcnn_write_byte(lp, ARCXCNN_COMP_CONFIG,
> > +			lp->pdata->comp_config);
> > +	if (lp->pdata->filter_config_set)
> > +		arcxcnn_write_byte(lp, ARCXCNN_FILT_CONFIG,
> > +			lp->pdata->filter_config);
> > +	if (lp->pdata->trim_config_set)
> > +		arcxcnn_write_byte(lp, ARCXCNN_IMAXTUNE,
> > +			lp->pdata->trim_config);
> > +
> > +	/* set initial LED Strings */
> > +	arcxcnn_update_bit(lp, ARCXCNN_LEDEN,
> > +		ARCXCNN_LEDEN_MASK, lp->pdata->led_str);
> > +
> > +	snprintf(lp->chipname, sizeof(lp->chipname),
> > +		"%s-%04X", id->name, chipid);
> > +
> > +	ret = arcxcnn_backlight_register(lp);
> > +	if (ret) {
> > +		dev_err(lp->dev,
> > +			"failed to register backlight. err: %d\n", ret);
> > +		return ret;
> > +	}
> > +
> > +	ret = sysfs_create_group(&lp->dev->kobj, &arcxcnn_attr_group);
> > +	if (ret) {
> > +		dev_err(lp->dev, "failed to register sysfs. err: %d\n", ret);
> > +		return ret;
> > +	}
> > +
> > +	backlight_update_status(lp->bl);
> > +	return 0;
> > +}
> > +
> > +static int arcxcnn_remove(struct i2c_client *cl)
> > +{
> > +	struct arcxcnn *lp = i2c_get_clientdata(cl);
> > +
> > +	if (!s_no_reset_on_remove) {
> > +		/* disable all strings */
> > +		arcxcnn_write_byte(lp, ARCXCNN_LEDEN, 0x00);
> > +		/* reset the device */
> > +		arcxcnn_write_byte(lp, ARCXCNN_CMD, ARCXCNN_CMD_RESET);
> > +	}
> > +	lp->bl->props.brightness = 0;
> > +	backlight_update_status(lp->bl);
> > +	if (lp->supply)
> > +		regulator_disable(lp->supply);
> > +	sysfs_remove_group(&lp->dev->kobj, &arcxcnn_attr_group);
> > +
> > +	return 0;
> > +}
> > +
> > +static const struct of_device_id arcxcnn_dt_ids[] = {
> > +	{ .compatible = "arc,arc2c0608" },
> > +	{ }
> > +};
> > +MODULE_DEVICE_TABLE(of, arcxcnn_dt_ids);
> > +
> > +/* Note that the device/chip ID is not fixed in silicon so
> > + * auto-probing of these devices on the bus is most likely
> > + * not possible, use device tree to set i2c bus address
> > + */
> > +static const struct i2c_device_id arcxcnn_ids[] = {
> > +	{"arc2c0608", ARC2C0608},
> > +	{ }
> > +};
> > +MODULE_DEVICE_TABLE(i2c, arcxcnn_ids);
> > +
> > +static struct i2c_driver arcxcnn_driver = {
> > +	.driver = {
> > +		   .name = "arcxcnn_bl",
> > +		   .of_match_table = of_match_ptr(arcxcnn_dt_ids),
> > +		   },
> > +	.probe = arcxcnn_probe,
> > +	.remove = arcxcnn_remove,
> > +	.id_table = arcxcnn_ids,
> > +};
> > +
> > +module_i2c_driver(arcxcnn_driver);
> > +
> > +MODULE_LICENSE("GPL v2");
> > +MODULE_AUTHOR("Brian Dodge <bdodge09@outlook.com>");
> > +MODULE_DESCRIPTION("ARCXCNN Backlight driver");
> > diff --git a/include/linux/i2c/arcxcnn.h b/include/linux/i2c/arcxcnn.h
> > new file mode 100644
> > index 0000000..1c681dd
> > --- /dev/null
> > +++ b/include/linux/i2c/arcxcnn.h
> > @@ -0,0 +1,67 @@
> > +/*
> > + * Backlight driver for ArcticSand ARC2C0608 Backlight Devices
> > + *
> > + * Copyright 2016 ArcticSand, Inc.
> > + *
> > + * Licensed under the GPL-2 or later.
> > + */
> > +
> > +#ifndef _ARCXCNN_H
> > +#define _ARCXCNN_H
> > +
> > +enum arcxcnn_chip_id {
> > +	ARC2C0608
> > +};
> > +
> > +enum arcxcnn_brightness_source {
> > +	ARCXCNN_PWM_ONLY,
> > +	ARCXCNN_I2C_ONLY = 2,
> > +};
> > +
> > +#define ARCXCNN_MAX_PROGENTRIES	48	/* max a/v pairs for custom */
> > +
> > +/**
> > + * struct arcxcnn_platform_data
> > + * @name : Backlight driver name. If it is not defined, default name is set.
> > + * @initial_brightness : initial value of backlight brightness
> > + * @led_str	 : initial LED string enables, upper bit is global on/off
> > + * @led_config_0 : fading speed (period between intensity steps)
> > + * @led_config_1 : misc settings, see datasheet
> > + * @dim_freq	 : pwm dimming frequency if in pwm mode
> > + * @comp_config	 : misc config, see datasheet
> > + * @filter_config: RC/PWM filter config, see datasheet
> > + * @trim_config	 : full scale current trim, see datasheet
> > + * @led_config_0_set	: the value in led_config_0 is valid
> > + * @led_config_1_set	: the value in led_config_1 is valid
> > + * @dim_freq_set	: the value in dim_freq is valid
> > + * @comp_config_set	: the value in comp_config is valid
> > + * @filter_config_set	: the value in filter_config is valid
> > + * @trim_config_set	: the value in trim_config is valid
> > + *
> > + * the _set flags are used to indicate that the value was explicitly set
> > + * in the device tree or platform data. settings not set are left as default
> > + * power-on default values of the chip except for led_str and led_config_1
> > + * which are set by the driver (led_str is specified indirectly in the
> > + * device tree via "led-sources")
> > + */
> > +struct arcxcnn_platform_data {
> > +	const char *name;
> > +	u16 initial_brightness;
> > +	u8	led_str;
> > +
> > +	u8	led_config_0;
> > +	u8	led_config_1;
> > +	u8	dim_freq;
> > +	u8	comp_config;
> > +	u8	filter_config;
> > +	u8	trim_config;
> > +
> > +	bool	led_config_0_set;
> > +	bool	led_config_1_set;
> > +	bool	dim_freq_set;
> > +	bool	comp_config_set;
> > +	bool	filter_config_set;
> > +	bool	trim_config_set;
> > +};
> > +
> > +#endif
> 

-- 
Lee Jones
Linaro STMicroelectronics Landing Team Lead
Linaro.org │ Open source software for ARM SoCs
Follow Linaro: Facebook | Twitter | Blog

Re: [PATCH 1/2] backlight: arcxcnn: add support for ArticSand devices

[Lee Jones]

Jingoo?

On Wed, 26 Oct 2016, Olimpiu Dejeu wrote:

> Resubmition of arcxcnn backliught driver adding devicetree entries
>  for all registers
> 
> Signed-off-by: Olimpiu Dejeu <olimpiu@arcticsand.com>
> 
> ---
>  drivers/video/backlight/Kconfig      |   7 +
>  drivers/video/backlight/Makefile     |   1 +
>  drivers/video/backlight/arcxcnn_bl.c | 541 +++++++++++++++++++++++++++++++++++
>  include/linux/i2c/arcxcnn.h          |  67 +++++
>  4 files changed, 616 insertions(+)
>  create mode 100644 drivers/video/backlight/arcxcnn_bl.c
>  create mode 100644 include/linux/i2c/arcxcnn.h
> 
> diff --git a/drivers/video/backlight/Kconfig b/drivers/video/backlight/Kconfig
> index 5ffa4b4..4e1d2ad 100644
> --- a/drivers/video/backlight/Kconfig
> +++ b/drivers/video/backlight/Kconfig
> @@ -460,6 +460,13 @@ config BACKLIGHT_BD6107
>  	help
>  	  If you have a Rohm BD6107 say Y to enable the backlight driver.
>  
> +config BACKLIGHT_ARCXCNN
> +	tristate "Backlight driver for the Arctic Sands ARCxCnnnn family"
> +	depends on I2C
> +	help
> +	  If you have an ARCxCnnnn family backlight say Y to enable
> +	  the backlight driver.
> +
>  endif # BACKLIGHT_CLASS_DEVICE
>  
>  endif # BACKLIGHT_LCD_SUPPORT
> diff --git a/drivers/video/backlight/Makefile b/drivers/video/backlight/Makefile
> index 16ec534..8905129 100644
> --- a/drivers/video/backlight/Makefile
> +++ b/drivers/video/backlight/Makefile
> @@ -55,3 +55,4 @@ obj-$(CONFIG_BACKLIGHT_SKY81452)	+= sky81452-backlight.o
>  obj-$(CONFIG_BACKLIGHT_TOSA)		+= tosa_bl.o
>  obj-$(CONFIG_BACKLIGHT_TPS65217)	+= tps65217_bl.o
>  obj-$(CONFIG_BACKLIGHT_WM831X)		+= wm831x_bl.o
> +obj-$(CONFIG_BACKLIGHT_ARCXCNN) 	+= arcxcnn_bl.o
> diff --git a/drivers/video/backlight/arcxcnn_bl.c b/drivers/video/backlight/arcxcnn_bl.c
> new file mode 100644
> index 0000000..1dad680
> --- /dev/null
> +++ b/drivers/video/backlight/arcxcnn_bl.c
> @@ -0,0 +1,541 @@
> +/*
> + * Backlight driver for ArcticSand ARC_X_C_0N_0N Devices
> + *
> + * Copyright 2016 ArcticSand, Inc.
> + *
> + * Licensed under the GPL-2 or later.
> + */
> +
> +#include <linux/module.h>
> +#include <linux/slab.h>
> +#include <linux/i2c.h>
> +#include <linux/backlight.h>
> +#include <linux/err.h>
> +#include <linux/of.h>
> +#include <linux/pwm.h>
> +#include <linux/regulator/consumer.h>
> +
> +#include "linux/i2c/arcxcnn.h"
> +
> +#define ARCXCNN_CMD		(0x00)  /* Command Register */
> +#define ARCXCNN_CMD_STDBY	(0x80)	/* I2C Standby */
> +#define ARCXCNN_CMD_RESET	(0x40)	/* Reset */
> +#define ARCXCNN_CMD_BOOST	(0x10)	/* Boost */
> +#define ARCXCNN_CMD_OVP_MASK	(0x0C)	/* --- Over Voltage Threshold */
> +#define ARCXCNN_CMD_OVP_XXV	(0x0C)	/* <rsvrd> Over Voltage Threshold */
> +#define ARCXCNN_CMD_OVP_20V	(0x08)	/* 20v Over Voltage Threshold */
> +#define ARCXCNN_CMD_OVP_24V	(0x04)	/* 24v Over Voltage Threshold */
> +#define ARCXCNN_CMD_OVP_31V	(0x00)	/* 31.4v Over Voltage Threshold */
> +#define ARCXCNN_CMD_EXT_COMP	(0x01)	/* part (0) or full (1) external comp */
> +
> +#define ARCXCNN_CONFIG	(0x01)  /* Configuration */
> +#define ARCXCNN_STATUS1	(0x02)  /* Status 1 */
> +#define ARCXCNN_STATUS2	(0x03)  /* Status 2 */
> +#define ARCXCNN_FADECTRL	(0x04)  /* Fading Control */
> +#define ARCXCNN_ILED_CONFIG	(0x05)  /* ILED Configuration */
> +
> +#define ARCXCNN_LEDEN		(0x06)  /* LED Enable Register */
> +#define ARCXCNN_LEDEN_ISETEXT	(0x80)	/* Full-scale current set externally */
> +#define ARCXCNN_LEDEN_MASK	(0x3F)	/* LED string enables */
> +#define ARCXCNN_LEDEN_LED1	(0x01)
> +#define ARCXCNN_LEDEN_LED2	(0x02)
> +#define ARCXCNN_LEDEN_LED3	(0x04)
> +#define ARCXCNN_LEDEN_LED4	(0x08)
> +#define ARCXCNN_LEDEN_LED5	(0x10)
> +#define ARCXCNN_LEDEN_LED6	(0x20)
> +
> +#define ARCXCNN_WLED_ISET_LSB	(0x07)  /* LED ISET LSB (in upper nibble) */
> +#define ARCXCNN_WLED_ISET_MSB	(0x08)  /* LED ISET MSB (8 bits) */
> +
> +#define ARCXCNN_DIMFREQ		(0x09)
> +#define ARCXCNN_COMP_CONFIG	(0x0A)
> +#define ARCXCNN_FILT_CONFIG	(0x0B)
> +#define ARCXCNN_IMAXTUNE	(0x0C)
> +
> +#define DEFAULT_BL_NAME		"arctic_bl"
> +#define MAX_BRIGHTNESS		4095
> +
> +static int s_no_reset_on_remove;
> +module_param_named(noreset, s_no_reset_on_remove, int, 0644);
> +MODULE_PARM_DESC(noreset, "No reset on module removal");
> +
> +static int s_ibright = 60;
> +module_param_named(ibright, s_ibright, int, 0644);
> +MODULE_PARM_DESC(ibright, "Initial brightness (when no plat data)");
> +
> +static int s_iledstr = 0x3F;
> +module_param_named(iledstr, s_iledstr, int, 0644);
> +MODULE_PARM_DESC(iledstr, "Initial LED String (when no plat data)");
> +
> +static int s_retries = 2; /* 1 == only one try */
> +module_param_named(retries, s_retries, int, 0644);
> +MODULE_PARM_DESC(retries, "I2C retries attempted");
> +
> +enum arcxcnn_brightness_ctrl_mode {
> +	PWM_BASED = 1,
> +	REGISTER_BASED,
> +};
> +
> +struct arcxcnn;
> +
> +struct arcxcnn {
> +	char chipname[64];
> +	enum arcxcnn_chip_id chip_id;
> +	enum arcxcnn_brightness_ctrl_mode mode;
> +	struct i2c_client *client;
> +	struct backlight_device *bl;
> +	struct device *dev;
> +	struct arcxcnn_platform_data *pdata;
> +	struct pwm_device *pwm;
> +	struct regulator *supply;	/* regulator for VDD input */
> +};
> +
> +static int arcxcnn_write_byte(struct arcxcnn *lp, u8 reg, u8 data)
> +{
> +	s32 ret = -1;
> +	int att;
> +
> +	for (att = 0; att < s_retries; att++) {
> +		ret = i2c_smbus_write_byte_data(lp->client, reg, data);
> +		if (ret >= 0)
> +			return 0;
> +	}
> +	return ret;
> +}
> +
> +static u8 arcxcnn_read_byte(struct arcxcnn *lp, u8 reg)
> +{
> +	int val;
> +	int att;
> +
> +	for (att = 0; att < s_retries; att++) {
> +		val = i2c_smbus_read_byte_data(lp->client, reg);
> +		if (val >= 0)
> +			return (u8)val;
> +	}
> +	return 0;
> +}
> +
> +static int arcxcnn_update_bit(struct arcxcnn *lp, u8 reg, u8 mask, u8 data)
> +{
> +	int ret, att;
> +	u8 tmp;
> +
> +	for (att = 0, ret = -1; att < s_retries; att++) {
> +		ret = i2c_smbus_read_byte_data(lp->client, reg);
> +		if (ret >= 0)
> +			break;
> +	}
> +	if (ret < 0) {
> +		dev_err(lp->dev, "failed to read 0x%.2x\n", reg);
> +		return ret;
> +	}
> +
> +	tmp = (u8)ret;
> +	tmp &= ~mask;
> +	tmp |= data & mask;
> +
> +	return arcxcnn_write_byte(lp, reg, tmp);
> +}
> +
> +static int arcxcnn_set_brightness(struct arcxcnn *lp, u32 brightness)
> +{
> +	int ret;
> +	u8 val;
> +
> +	val = (brightness & 0xF) << 4;
> +	ret = arcxcnn_write_byte(lp, ARCXCNN_WLED_ISET_LSB, val);
> +	if (ret < 0)
> +		return ret;
> +	val = (brightness >> 4);
> +	ret = arcxcnn_write_byte(lp, ARCXCNN_WLED_ISET_MSB, val);
> +	return ret;
> +}
> +
> +static int arcxcnn_bl_update_status(struct backlight_device *bl)
> +{
> +	struct arcxcnn *lp = bl_get_data(bl);
> +	u32 brightness = bl->props.brightness;
> +
> +	if (bl->props.state & (BL_CORE_SUSPENDED | BL_CORE_FBBLANK))
> +		brightness = 0;
> +
> +	/* set brightness */
> +	if (lp->mode == PWM_BASED)
> +		; /* via pwm */
> +	else if (lp->mode == REGISTER_BASED)
> +		arcxcnn_set_brightness(lp, brightness);
> +
> +	/* set power-on/off/save modes */
> +	if (bl->props.power == 0)
> +		/* take out of standby */
> +		arcxcnn_update_bit(lp, ARCXCNN_CMD, ARCXCNN_CMD_STDBY, 0);
> +	else
> +		/* 1-3 == power save, 4 = off
> +		 * place in low-power standby mode
> +		 */
> +		arcxcnn_update_bit(lp, ARCXCNN_CMD,
> +				ARCXCNN_CMD_STDBY, ARCXCNN_CMD_STDBY);
> +	return 0;
> +}
> +
> +static const struct backlight_ops arcxcnn_bl_ops = {
> +	.options = BL_CORE_SUSPENDRESUME,
> +	.update_status = arcxcnn_bl_update_status,
> +};
> +
> +static int arcxcnn_backlight_register(struct arcxcnn *lp)
> +{
> +	struct backlight_device *bl;
> +	struct backlight_properties props;
> +	struct arcxcnn_platform_data *pdata = lp->pdata;
> +	const char *name = pdata->name ? : DEFAULT_BL_NAME;
> +
> +	memset(&props, 0, sizeof(props));
> +	props.type = BACKLIGHT_PLATFORM;
> +	props.max_brightness = MAX_BRIGHTNESS;
> +
> +	if (pdata->initial_brightness > props.max_brightness)
> +		pdata->initial_brightness = props.max_brightness;
> +
> +	props.brightness = pdata->initial_brightness;
> +
> +	bl = devm_backlight_device_register(lp->dev, name, lp->dev, lp,
> +				       &arcxcnn_bl_ops, &props);
> +	if (IS_ERR(bl))
> +		return PTR_ERR(bl);
> +
> +	lp->bl = bl;
> +
> +	return 0;
> +}
> +
> +static ssize_t arcxcnn_get_chip_id(struct device *dev,
> +		struct device_attribute *attr, char *buf)
> +{
> +	struct arcxcnn *lp = dev_get_drvdata(dev);
> +
> +	return scnprintf(buf, PAGE_SIZE, "%s\n", lp->chipname);
> +}
> +
> +static ssize_t arcxcnn_get_led_str(struct device *dev,
> +		struct device_attribute *attr, char *buf)
> +{
> +	struct arcxcnn *lp = dev_get_drvdata(dev);
> +
> +	return scnprintf(buf, PAGE_SIZE, "%02X\n", lp->pdata->led_str);
> +}
> +
> +static ssize_t arcxcnn_set_led_str(struct device *dev,
> +		struct device_attribute *attr, const char *buf, size_t len)
> +{
> +	struct arcxcnn *lp = dev_get_drvdata(dev);
> +	unsigned long ledstr;
> +
> +	if (kstrtoul(buf, 0, &ledstr))
> +		return 0;
> +
> +	if (ledstr != lp->pdata->led_str) {
> +		/* don't allow 0 for ledstr, use power to turn all off */
> +		if (ledstr == 0)
> +			return 0;
> +		lp->pdata->led_str = ledstr & 0x3F;
> +		arcxcnn_update_bit(lp, ARCXCNN_LEDEN,
> +			ARCXCNN_LEDEN_MASK, lp->pdata->led_str);
> +	}
> +	return len;
> +}
> +
> +static ssize_t arcxcnn_get_bl_ctl_mode(struct device *dev,
> +	     struct device_attribute *attr, char *buf)
> +{
> +	struct arcxcnn *lp = dev_get_drvdata(dev);
> +	char *strmode = NULL;
> +
> +	if (lp->mode == PWM_BASED)
> +		strmode = "pwm based";
> +	else if (lp->mode == REGISTER_BASED)
> +		strmode = "register based";
> +
> +	return scnprintf(buf, PAGE_SIZE, "%s\n", strmode);
> +}
> +
> +static DEVICE_ATTR(chip_id, 0444, arcxcnn_get_chip_id, NULL);
> +static DEVICE_ATTR(led_str, 0664, arcxcnn_get_led_str, arcxcnn_set_led_str);
> +static DEVICE_ATTR(bl_ctl_mode, 0444, arcxcnn_get_bl_ctl_mode, NULL);
> +
> +static struct attribute *arcxcnn_attributes[] = {
> +	&dev_attr_chip_id.attr,
> +	&dev_attr_led_str.attr,
> +	&dev_attr_bl_ctl_mode.attr,
> +	NULL,
> +};
> +
> +static const struct attribute_group arcxcnn_attr_group = {
> +	.attrs = arcxcnn_attributes,
> +};
> +
> +#ifdef CONFIG_OF
> +static int arcxcnn_parse_dt(struct arcxcnn *lp)
> +{
> +	struct device *dev = lp->dev;
> +	struct device_node *node = dev->of_node;
> +	u32 prog_val, num_entry, sources[6];
> +	int ret;
> +
> +	if (!node) {
> +		dev_err(dev, "no platform data.\n");
> +		return -EINVAL;
> +	}
> +	lp->pdata->led_config_0_set = false;
> +	lp->pdata->led_config_1_set = false;
> +	lp->pdata->dim_freq_set = false;
> +	lp->pdata->comp_config_set = false;
> +	lp->pdata->filter_config_set = false;
> +	lp->pdata->trim_config_set = false;
> +
> +	ret = of_property_read_string(node, "label", &lp->pdata->name);
> +	if (ret < 0)
> +		lp->pdata->name = NULL;
> +
> +	ret = of_property_read_u32(node, "default-brightness", &prog_val);
> +	if (ret < 0)
> +		prog_val = s_ibright;
> +	lp->pdata->initial_brightness = prog_val;
> +	if (lp->pdata->initial_brightness > MAX_BRIGHTNESS)
> +		lp->pdata->initial_brightness = MAX_BRIGHTNESS;
> +
> +	ret = of_property_read_u32(node, "arcticsand,led-config-0", &prog_val);
> +	if (ret == 0) {
> +		lp->pdata->led_config_0 = (u8)prog_val;
> +		lp->pdata->led_config_0_set = true;
> +	}
> +	ret = of_property_read_u32(node, "arcticsand,led-config-1", &prog_val);
> +	if (ret == 0) {
> +		lp->pdata->led_config_1 = (u8)prog_val;
> +		lp->pdata->led_config_1_set = true;
> +	}
> +	ret = of_property_read_u32(node, "arcticsand,dim-freq", &prog_val);
> +	if (ret == 0) {
> +		lp->pdata->dim_freq = (u8)prog_val;
> +		lp->pdata->dim_freq_set = true;
> +	}
> +	ret = of_property_read_u32(node, "arcticsand,comp-config", &prog_val);
> +	if (ret == 0) {
> +		lp->pdata->comp_config = (u8)prog_val;
> +		lp->pdata->comp_config_set = true;
> +	}
> +	ret = of_property_read_u32(node, "arcticsand,filter-config", &prog_val);
> +	if (ret == 0) {
> +		lp->pdata->filter_config = (u8)prog_val;
> +		lp->pdata->filter_config_set = true;
> +	}
> +	ret = of_property_read_u32(node, "arcticsand,trim-config", &prog_val);
> +	if (ret == 0) {
> +		lp->pdata->trim_config = (u8)prog_val;
> +		lp->pdata->trim_config_set = true;
> +	}
> +	ret = of_property_count_u32_elems(node, "led-sources");
> +	if (ret < 0)
> +		lp->pdata->led_str = 0x3F;
> +	else {
> +		num_entry = ret;
> +		if (num_entry > 6)
> +			num_entry = 6;
> +
> +		ret = of_property_read_u32_array(node, "led-sources", sources,
> +					num_entry);
> +		if (ret < 0) {
> +			dev_err(dev, "led-sources node is invalid.\n");
> +			return -EINVAL;
> +		}
> +
> +		lp->pdata->led_str = 0;
> +		while (num_entry > 0)
> +			lp->pdata->led_str |= (1 << sources[--num_entry]);
> +	}
> +	return 0;
> +}
> +#else
> +static int arcxcnn_parse_dt(struct arcxcnn *lp)
> +{
> +	return -EINVAL;
> +}
> +#endif
> +
> +static int arcxcnn_probe(struct i2c_client *cl, const struct i2c_device_id *id)
> +{
> +	struct arcxcnn *lp;
> +	int ret;
> +	u8 regval;
> +	u16 chipid;
> +
> +	if (!i2c_check_functionality(cl->adapter, I2C_FUNC_SMBUS_BYTE_DATA))
> +		return -EIO;
> +
> +	lp = devm_kzalloc(&cl->dev, sizeof(*lp), GFP_KERNEL);
> +	if (!lp)
> +		return -ENOMEM;
> +
> +	lp->client = cl;
> +	lp->dev = &cl->dev;
> +	lp->chip_id = id->driver_data;
> +	lp->pdata = dev_get_platdata(&cl->dev);
> +
> +	if (!lp->pdata) {
> +		lp->pdata = devm_kzalloc(lp->dev,
> +				sizeof(*lp->pdata), GFP_KERNEL);
> +		if (!lp->pdata)
> +			return -ENOMEM;
> +
> +		/* no platform data, parse the device-tree for info.  if there
> +		 * is no device tree entry, we are being told we exist because
> +		 * user-land said so, so make up the info we need
> +		 */
> +		ret = arcxcnn_parse_dt(lp);
> +		if (ret < 0) {
> +			/* no device tree, use defaults based on module params
> +			 */
> +			lp->pdata->led_config_0_set = false;
> +			lp->pdata->led_config_1_set = false;
> +			lp->pdata->dim_freq_set = false;
> +			lp->pdata->comp_config_set = false;
> +			lp->pdata->filter_config_set = false;
> +			lp->pdata->trim_config_set = false;
> +
> +			lp->pdata->name = NULL;
> +			lp->pdata->initial_brightness = s_ibright;
> +			lp->pdata->led_str = s_iledstr;
> +		}
> +	}
> +
> +	if (lp->pdata->dim_freq_set)
> +		lp->mode = PWM_BASED;
> +	else
> +		lp->mode = REGISTER_BASED;
> +
> +	i2c_set_clientdata(cl, lp);
> +
> +	/* read device ID */
> +	regval = arcxcnn_read_byte(lp, 0x1E);
> +	chipid = regval;
> +	chipid <<= 8;
> +	regval = arcxcnn_read_byte(lp, 0x1F);
> +	chipid |= regval;
> +
> +	/* make sure it belongs to this driver
> +	 * TODO - handle specific ids
> +	 */
> +	if (chipid != 0x02A5) {
> +		#if 1
> +		dev_info(&cl->dev, "Chip Id is %04X\n", chipid);
> +		#else
> +		dev_err(&cl->dev, "%04X is not ARC2C\n", chipid);
> +		return -ENODEV;
> +		#endif
> +	}
> +	/* reset the device */
> +	arcxcnn_write_byte(lp, ARCXCNN_CMD, ARCXCNN_CMD_RESET);
> +
> +	/* set initial brightness */
> +	arcxcnn_set_brightness(lp, lp->pdata->initial_brightness);
> +
> +	/* if fadectrl set in DT, set the value directly, else leave default */
> +	if (lp->pdata->led_config_0_set)
> +		arcxcnn_write_byte(lp, ARCXCNN_FADECTRL,
> +			lp->pdata->led_config_0);
> +
> +	/* if iled config set in DT, set the value, else internal mode */
> +	if (lp->pdata->led_config_1_set)
> +		arcxcnn_write_byte(lp, ARCXCNN_ILED_CONFIG,
> +			lp->pdata->led_config_1);
> +	else
> +		arcxcnn_write_byte(lp, ARCXCNN_ILED_CONFIG, 0x57);
> +
> +	/* other misc DT settings */
> +	if (lp->pdata->dim_freq_set)
> +		arcxcnn_write_byte(lp, ARCXCNN_FADECTRL, lp->pdata->dim_freq);
> +	if (lp->pdata->comp_config_set)
> +		arcxcnn_write_byte(lp, ARCXCNN_COMP_CONFIG,
> +			lp->pdata->comp_config);
> +	if (lp->pdata->filter_config_set)
> +		arcxcnn_write_byte(lp, ARCXCNN_FILT_CONFIG,
> +			lp->pdata->filter_config);
> +	if (lp->pdata->trim_config_set)
> +		arcxcnn_write_byte(lp, ARCXCNN_IMAXTUNE,
> +			lp->pdata->trim_config);
> +
> +	/* set initial LED Strings */
> +	arcxcnn_update_bit(lp, ARCXCNN_LEDEN,
> +		ARCXCNN_LEDEN_MASK, lp->pdata->led_str);
> +
> +	snprintf(lp->chipname, sizeof(lp->chipname),
> +		"%s-%04X", id->name, chipid);
> +
> +	ret = arcxcnn_backlight_register(lp);
> +	if (ret) {
> +		dev_err(lp->dev,
> +			"failed to register backlight. err: %d\n", ret);
> +		return ret;
> +	}
> +
> +	ret = sysfs_create_group(&lp->dev->kobj, &arcxcnn_attr_group);
> +	if (ret) {
> +		dev_err(lp->dev, "failed to register sysfs. err: %d\n", ret);
> +		return ret;
> +	}
> +
> +	backlight_update_status(lp->bl);
> +	return 0;
> +}
> +
> +static int arcxcnn_remove(struct i2c_client *cl)
> +{
> +	struct arcxcnn *lp = i2c_get_clientdata(cl);
> +
> +	if (!s_no_reset_on_remove) {
> +		/* disable all strings */
> +		arcxcnn_write_byte(lp, ARCXCNN_LEDEN, 0x00);
> +		/* reset the device */
> +		arcxcnn_write_byte(lp, ARCXCNN_CMD, ARCXCNN_CMD_RESET);
> +	}
> +	lp->bl->props.brightness = 0;
> +	backlight_update_status(lp->bl);
> +	if (lp->supply)
> +		regulator_disable(lp->supply);
> +	sysfs_remove_group(&lp->dev->kobj, &arcxcnn_attr_group);
> +
> +	return 0;
> +}
> +
> +static const struct of_device_id arcxcnn_dt_ids[] = {
> +	{ .compatible = "arc,arc2c0608" },
> +	{ }
> +};
> +MODULE_DEVICE_TABLE(of, arcxcnn_dt_ids);
> +
> +/* Note that the device/chip ID is not fixed in silicon so
> + * auto-probing of these devices on the bus is most likely
> + * not possible, use device tree to set i2c bus address
> + */
> +static const struct i2c_device_id arcxcnn_ids[] = {
> +	{"arc2c0608", ARC2C0608},
> +	{ }
> +};
> +MODULE_DEVICE_TABLE(i2c, arcxcnn_ids);
> +
> +static struct i2c_driver arcxcnn_driver = {
> +	.driver = {
> +		   .name = "arcxcnn_bl",
> +		   .of_match_table = of_match_ptr(arcxcnn_dt_ids),
> +		   },
> +	.probe = arcxcnn_probe,
> +	.remove = arcxcnn_remove,
> +	.id_table = arcxcnn_ids,
> +};
> +
> +module_i2c_driver(arcxcnn_driver);
> +
> +MODULE_LICENSE("GPL v2");
> +MODULE_AUTHOR("Brian Dodge <bdodge09@outlook.com>");
> +MODULE_DESCRIPTION("ARCXCNN Backlight driver");
> diff --git a/include/linux/i2c/arcxcnn.h b/include/linux/i2c/arcxcnn.h
> new file mode 100644
> index 0000000..1c681dd
> --- /dev/null
> +++ b/include/linux/i2c/arcxcnn.h
> @@ -0,0 +1,67 @@
> +/*
> + * Backlight driver for ArcticSand ARC2C0608 Backlight Devices
> + *
> + * Copyright 2016 ArcticSand, Inc.
> + *
> + * Licensed under the GPL-2 or later.
> + */
> +
> +#ifndef _ARCXCNN_H
> +#define _ARCXCNN_H
> +
> +enum arcxcnn_chip_id {
> +	ARC2C0608
> +};
> +
> +enum arcxcnn_brightness_source {
> +	ARCXCNN_PWM_ONLY,
> +	ARCXCNN_I2C_ONLY = 2,
> +};
> +
> +#define ARCXCNN_MAX_PROGENTRIES	48	/* max a/v pairs for custom */
> +
> +/**
> + * struct arcxcnn_platform_data
> + * @name : Backlight driver name. If it is not defined, default name is set.
> + * @initial_brightness : initial value of backlight brightness
> + * @led_str	 : initial LED string enables, upper bit is global on/off
> + * @led_config_0 : fading speed (period between intensity steps)
> + * @led_config_1 : misc settings, see datasheet
> + * @dim_freq	 : pwm dimming frequency if in pwm mode
> + * @comp_config	 : misc config, see datasheet
> + * @filter_config: RC/PWM filter config, see datasheet
> + * @trim_config	 : full scale current trim, see datasheet
> + * @led_config_0_set	: the value in led_config_0 is valid
> + * @led_config_1_set	: the value in led_config_1 is valid
> + * @dim_freq_set	: the value in dim_freq is valid
> + * @comp_config_set	: the value in comp_config is valid
> + * @filter_config_set	: the value in filter_config is valid
> + * @trim_config_set	: the value in trim_config is valid
> + *
> + * the _set flags are used to indicate that the value was explicitly set
> + * in the device tree or platform data. settings not set are left as default
> + * power-on default values of the chip except for led_str and led_config_1
> + * which are set by the driver (led_str is specified indirectly in the
> + * device tree via "led-sources")
> + */
> +struct arcxcnn_platform_data {
> +	const char *name;
> +	u16 initial_brightness;
> +	u8	led_str;
> +
> +	u8	led_config_0;
> +	u8	led_config_1;
> +	u8	dim_freq;
> +	u8	comp_config;
> +	u8	filter_config;
> +	u8	trim_config;
> +
> +	bool	led_config_0_set;
> +	bool	led_config_1_set;
> +	bool	dim_freq_set;
> +	bool	comp_config_set;
> +	bool	filter_config_set;
> +	bool	trim_config_set;
> +};
> +
> +#endif

-- 
Lee Jones
Linaro STMicroelectronics Landing Team Lead
Linaro.org │ Open source software for ARM SoCs
Follow Linaro: Facebook | Twitter | Blog

[PATCH 1/2] backlight: arcxcnn: add support for ArticSand devices

[Olimpiu Dejeu]

Resubmition of arcxcnn backliught driver addressing the naming convention
 concerns raised by Rob H. 

Signed-off-by: Olimpiu Dejeu <olimpiu@arcticsand.com>

---
 drivers/video/backlight/Kconfig      |   7 +
 drivers/video/backlight/Makefile     |   1 +
 drivers/video/backlight/arcxcnn_bl.c | 541 +++++++++++++++++++++++++++++++++++
 include/linux/i2c/arcxcnn.h          |  67 +++++
 4 files changed, 616 insertions(+)
 create mode 100644 drivers/video/backlight/arcxcnn_bl.c
 create mode 100644 include/linux/i2c/arcxcnn.h

diff --git a/drivers/video/backlight/Kconfig b/drivers/video/backlight/Kconfig
index 5ffa4b4..4e1d2ad 100644
--- a/drivers/video/backlight/Kconfig
+++ b/drivers/video/backlight/Kconfig
@@ -460,6 +460,13 @@ config BACKLIGHT_BD6107
 	help
 	  If you have a Rohm BD6107 say Y to enable the backlight driver.
 
+config BACKLIGHT_ARCXCNN
+	tristate "Backlight driver for the Arctic Sands ARCxCnnnn family"
+	depends on I2C
+	help
+	  If you have an ARCxCnnnn family backlight say Y to enable
+	  the backlight driver.
+
 endif # BACKLIGHT_CLASS_DEVICE
 
 endif # BACKLIGHT_LCD_SUPPORT
diff --git a/drivers/video/backlight/Makefile b/drivers/video/backlight/Makefile
index 16ec534..8905129 100644
--- a/drivers/video/backlight/Makefile
+++ b/drivers/video/backlight/Makefile
@@ -55,3 +55,4 @@ obj-$(CONFIG_BACKLIGHT_SKY81452)	+= sky81452-backlight.o
 obj-$(CONFIG_BACKLIGHT_TOSA)		+= tosa_bl.o
 obj-$(CONFIG_BACKLIGHT_TPS65217)	+= tps65217_bl.o
 obj-$(CONFIG_BACKLIGHT_WM831X)		+= wm831x_bl.o
+obj-$(CONFIG_BACKLIGHT_ARCXCNN) 	+= arcxcnn_bl.o
diff --git a/drivers/video/backlight/arcxcnn_bl.c b/drivers/video/backlight/arcxcnn_bl.c
new file mode 100644
index 0000000..1dad680
--- /dev/null
+++ b/drivers/video/backlight/arcxcnn_bl.c
@@ -0,0 +1,541 @@
+/*
+ * Backlight driver for ArcticSand ARC_X_C_0N_0N Devices
+ *
+ * Copyright 2016 ArcticSand, Inc.
+ *
+ * Licensed under the GPL-2 or later.
+ */
+
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/i2c.h>
+#include <linux/backlight.h>
+#include <linux/err.h>
+#include <linux/of.h>
+#include <linux/pwm.h>
+#include <linux/regulator/consumer.h>
+
+#include "linux/i2c/arcxcnn.h"
+
+#define ARCXCNN_CMD		(0x00)  /* Command Register */
+#define ARCXCNN_CMD_STDBY	(0x80)	/* I2C Standby */
+#define ARCXCNN_CMD_RESET	(0x40)	/* Reset */
+#define ARCXCNN_CMD_BOOST	(0x10)	/* Boost */
+#define ARCXCNN_CMD_OVP_MASK	(0x0C)	/* --- Over Voltage Threshold */
+#define ARCXCNN_CMD_OVP_XXV	(0x0C)	/* <rsvrd> Over Voltage Threshold */
+#define ARCXCNN_CMD_OVP_20V	(0x08)	/* 20v Over Voltage Threshold */
+#define ARCXCNN_CMD_OVP_24V	(0x04)	/* 24v Over Voltage Threshold */
+#define ARCXCNN_CMD_OVP_31V	(0x00)	/* 31.4v Over Voltage Threshold */
+#define ARCXCNN_CMD_EXT_COMP	(0x01)	/* part (0) or full (1) external comp */
+
+#define ARCXCNN_CONFIG	(0x01)  /* Configuration */
+#define ARCXCNN_STATUS1	(0x02)  /* Status 1 */
+#define ARCXCNN_STATUS2	(0x03)  /* Status 2 */
+#define ARCXCNN_FADECTRL	(0x04)  /* Fading Control */
+#define ARCXCNN_ILED_CONFIG	(0x05)  /* ILED Configuration */
+
+#define ARCXCNN_LEDEN		(0x06)  /* LED Enable Register */
+#define ARCXCNN_LEDEN_ISETEXT	(0x80)	/* Full-scale current set externally */
+#define ARCXCNN_LEDEN_MASK	(0x3F)	/* LED string enables */
+#define ARCXCNN_LEDEN_LED1	(0x01)
+#define ARCXCNN_LEDEN_LED2	(0x02)
+#define ARCXCNN_LEDEN_LED3	(0x04)
+#define ARCXCNN_LEDEN_LED4	(0x08)
+#define ARCXCNN_LEDEN_LED5	(0x10)
+#define ARCXCNN_LEDEN_LED6	(0x20)
+
+#define ARCXCNN_WLED_ISET_LSB	(0x07)  /* LED ISET LSB (in upper nibble) */
+#define ARCXCNN_WLED_ISET_MSB	(0x08)  /* LED ISET MSB (8 bits) */
+
+#define ARCXCNN_DIMFREQ		(0x09)
+#define ARCXCNN_COMP_CONFIG	(0x0A)
+#define ARCXCNN_FILT_CONFIG	(0x0B)
+#define ARCXCNN_IMAXTUNE	(0x0C)
+
+#define DEFAULT_BL_NAME		"arctic_bl"
+#define MAX_BRIGHTNESS		4095
+
+static int s_no_reset_on_remove;
+module_param_named(noreset, s_no_reset_on_remove, int, 0644);
+MODULE_PARM_DESC(noreset, "No reset on module removal");
+
+static int s_ibright = 60;
+module_param_named(ibright, s_ibright, int, 0644);
+MODULE_PARM_DESC(ibright, "Initial brightness (when no plat data)");
+
+static int s_iledstr = 0x3F;
+module_param_named(iledstr, s_iledstr, int, 0644);
+MODULE_PARM_DESC(iledstr, "Initial LED String (when no plat data)");
+
+static int s_retries = 2; /* 1 == only one try */
+module_param_named(retries, s_retries, int, 0644);
+MODULE_PARM_DESC(retries, "I2C retries attempted");
+
+enum arcxcnn_brightness_ctrl_mode {
+	PWM_BASED = 1,
+	REGISTER_BASED,
+};
+
+struct arcxcnn;
+
+struct arcxcnn {
+	char chipname[64];
+	enum arcxcnn_chip_id chip_id;
+	enum arcxcnn_brightness_ctrl_mode mode;
+	struct i2c_client *client;
+	struct backlight_device *bl;
+	struct device *dev;
+	struct arcxcnn_platform_data *pdata;
+	struct pwm_device *pwm;
+	struct regulator *supply;	/* regulator for VDD input */
+};
+
+static int arcxcnn_write_byte(struct arcxcnn *lp, u8 reg, u8 data)
+{
+	s32 ret = -1;
+	int att;
+
+	for (att = 0; att < s_retries; att++) {
+		ret = i2c_smbus_write_byte_data(lp->client, reg, data);
+		if (ret >= 0)
+			return 0;
+	}
+	return ret;
+}
+
+static u8 arcxcnn_read_byte(struct arcxcnn *lp, u8 reg)
+{
+	int val;
+	int att;
+
+	for (att = 0; att < s_retries; att++) {
+		val = i2c_smbus_read_byte_data(lp->client, reg);
+		if (val >= 0)
+			return (u8)val;
+	}
+	return 0;
+}
+
+static int arcxcnn_update_bit(struct arcxcnn *lp, u8 reg, u8 mask, u8 data)
+{
+	int ret, att;
+	u8 tmp;
+
+	for (att = 0, ret = -1; att < s_retries; att++) {
+		ret = i2c_smbus_read_byte_data(lp->client, reg);
+		if (ret >= 0)
+			break;
+	}
+	if (ret < 0) {
+		dev_err(lp->dev, "failed to read 0x%.2x\n", reg);
+		return ret;
+	}
+
+	tmp = (u8)ret;
+	tmp &= ~mask;
+	tmp |= data & mask;
+
+	return arcxcnn_write_byte(lp, reg, tmp);
+}
+
+static int arcxcnn_set_brightness(struct arcxcnn *lp, u32 brightness)
+{
+	int ret;
+	u8 val;
+
+	val = (brightness & 0xF) << 4;
+	ret = arcxcnn_write_byte(lp, ARCXCNN_WLED_ISET_LSB, val);
+	if (ret < 0)
+		return ret;
+	val = (brightness >> 4);
+	ret = arcxcnn_write_byte(lp, ARCXCNN_WLED_ISET_MSB, val);
+	return ret;
+}
+
+static int arcxcnn_bl_update_status(struct backlight_device *bl)
+{
+	struct arcxcnn *lp = bl_get_data(bl);
+	u32 brightness = bl->props.brightness;
+
+	if (bl->props.state & (BL_CORE_SUSPENDED | BL_CORE_FBBLANK))
+		brightness = 0;
+
+	/* set brightness */
+	if (lp->mode == PWM_BASED)
+		; /* via pwm */
+	else if (lp->mode == REGISTER_BASED)
+		arcxcnn_set_brightness(lp, brightness);
+
+	/* set power-on/off/save modes */
+	if (bl->props.power == 0)
+		/* take out of standby */
+		arcxcnn_update_bit(lp, ARCXCNN_CMD, ARCXCNN_CMD_STDBY, 0);
+	else
+		/* 1-3 == power save, 4 = off
+		 * place in low-power standby mode
+		 */
+		arcxcnn_update_bit(lp, ARCXCNN_CMD,
+				ARCXCNN_CMD_STDBY, ARCXCNN_CMD_STDBY);
+	return 0;
+}
+
+static const struct backlight_ops arcxcnn_bl_ops = {
+	.options = BL_CORE_SUSPENDRESUME,
+	.update_status = arcxcnn_bl_update_status,
+};
+
+static int arcxcnn_backlight_register(struct arcxcnn *lp)
+{
+	struct backlight_device *bl;
+	struct backlight_properties props;
+	struct arcxcnn_platform_data *pdata = lp->pdata;
+	const char *name = pdata->name ? : DEFAULT_BL_NAME;
+
+	memset(&props, 0, sizeof(props));
+	props.type = BACKLIGHT_PLATFORM;
+	props.max_brightness = MAX_BRIGHTNESS;
+
+	if (pdata->initial_brightness > props.max_brightness)
+		pdata->initial_brightness = props.max_brightness;
+
+	props.brightness = pdata->initial_brightness;
+
+	bl = devm_backlight_device_register(lp->dev, name, lp->dev, lp,
+				       &arcxcnn_bl_ops, &props);
+	if (IS_ERR(bl))
+		return PTR_ERR(bl);
+
+	lp->bl = bl;
+
+	return 0;
+}
+
+static ssize_t arcxcnn_get_chip_id(struct device *dev,
+		struct device_attribute *attr, char *buf)
+{
+	struct arcxcnn *lp = dev_get_drvdata(dev);
+
+	return scnprintf(buf, PAGE_SIZE, "%s\n", lp->chipname);
+}
+
+static ssize_t arcxcnn_get_led_str(struct device *dev,
+		struct device_attribute *attr, char *buf)
+{
+	struct arcxcnn *lp = dev_get_drvdata(dev);
+
+	return scnprintf(buf, PAGE_SIZE, "%02X\n", lp->pdata->led_str);
+}
+
+static ssize_t arcxcnn_set_led_str(struct device *dev,
+		struct device_attribute *attr, const char *buf, size_t len)
+{
+	struct arcxcnn *lp = dev_get_drvdata(dev);
+	unsigned long ledstr;
+
+	if (kstrtoul(buf, 0, &ledstr))
+		return 0;
+
+	if (ledstr != lp->pdata->led_str) {
+		/* don't allow 0 for ledstr, use power to turn all off */
+		if (ledstr == 0)
+			return 0;
+		lp->pdata->led_str = ledstr & 0x3F;
+		arcxcnn_update_bit(lp, ARCXCNN_LEDEN,
+			ARCXCNN_LEDEN_MASK, lp->pdata->led_str);
+	}
+	return len;
+}
+
+static ssize_t arcxcnn_get_bl_ctl_mode(struct device *dev,
+	     struct device_attribute *attr, char *buf)
+{
+	struct arcxcnn *lp = dev_get_drvdata(dev);
+	char *strmode = NULL;
+
+	if (lp->mode == PWM_BASED)
+		strmode = "pwm based";
+	else if (lp->mode == REGISTER_BASED)
+		strmode = "register based";
+
+	return scnprintf(buf, PAGE_SIZE, "%s\n", strmode);
+}
+
+static DEVICE_ATTR(chip_id, 0444, arcxcnn_get_chip_id, NULL);
+static DEVICE_ATTR(led_str, 0664, arcxcnn_get_led_str, arcxcnn_set_led_str);
+static DEVICE_ATTR(bl_ctl_mode, 0444, arcxcnn_get_bl_ctl_mode, NULL);
+
+static struct attribute *arcxcnn_attributes[] = {
+	&dev_attr_chip_id.attr,
+	&dev_attr_led_str.attr,
+	&dev_attr_bl_ctl_mode.attr,
+	NULL,
+};
+
+static const struct attribute_group arcxcnn_attr_group = {
+	.attrs = arcxcnn_attributes,
+};
+
+#ifdef CONFIG_OF
+static int arcxcnn_parse_dt(struct arcxcnn *lp)
+{
+	struct device *dev = lp->dev;
+	struct device_node *node = dev->of_node;
+	u32 prog_val, num_entry, sources[6];
+	int ret;
+
+	if (!node) {
+		dev_err(dev, "no platform data.\n");
+		return -EINVAL;
+	}
+	lp->pdata->led_config_0_set = false;
+	lp->pdata->led_config_1_set = false;
+	lp->pdata->dim_freq_set = false;
+	lp->pdata->comp_config_set = false;
+	lp->pdata->filter_config_set = false;
+	lp->pdata->trim_config_set = false;
+
+	ret = of_property_read_string(node, "label", &lp->pdata->name);
+	if (ret < 0)
+		lp->pdata->name = NULL;
+
+	ret = of_property_read_u32(node, "default-brightness", &prog_val);
+	if (ret < 0)
+		prog_val = s_ibright;
+	lp->pdata->initial_brightness = prog_val;
+	if (lp->pdata->initial_brightness > MAX_BRIGHTNESS)
+		lp->pdata->initial_brightness = MAX_BRIGHTNESS;
+
+	ret = of_property_read_u32(node, "arc,led-config-0", &prog_val);
+	if (ret == 0) {
+		lp->pdata->led_config_0 = (u8)prog_val;
+		lp->pdata->led_config_0_set = true;
+	}
+	ret = of_property_read_u32(node, "arc,led-config-1", &prog_val);
+	if (ret == 0) {
+		lp->pdata->led_config_1 = (u8)prog_val;
+		lp->pdata->led_config_1_set = true;
+	}
+	ret = of_property_read_u32(node, "arc,dim-freq", &prog_val);
+	if (ret == 0) {
+		lp->pdata->dim_freq = (u8)prog_val;
+		lp->pdata->dim_freq_set = true;
+	}
+	ret = of_property_read_u32(node, "arc,comp-config", &prog_val);
+	if (ret == 0) {
+		lp->pdata->comp_config = (u8)prog_val;
+		lp->pdata->comp_config_set = true;
+	}
+	ret = of_property_read_u32(node, "arc,filter-config", &prog_val);
+	if (ret == 0) {
+		lp->pdata->filter_config = (u8)prog_val;
+		lp->pdata->filter_config_set = true;
+	}
+	ret = of_property_read_u32(node, "arc,trim-config", &prog_val);
+	if (ret == 0) {
+		lp->pdata->trim_config = (u8)prog_val;
+		lp->pdata->trim_config_set = true;
+	}
+	ret = of_property_count_u32_elems(node, "led-sources");
+	if (ret < 0)
+		lp->pdata->led_str = 0x3F;
+	else {
+		num_entry = ret;
+		if (num_entry > 6)
+			num_entry = 6;
+
+		ret = of_property_read_u32_array(node, "led-sources", sources,
+					num_entry);
+		if (ret < 0) {
+			dev_err(dev, "led-sources node is invalid.\n");
+			return -EINVAL;
+		}
+
+		lp->pdata->led_str = 0;
+		while (num_entry > 0)
+			lp->pdata->led_str |= (1 << sources[--num_entry]);
+	}
+	return 0;
+}
+#else
+static int arcxcnn_parse_dt(struct arcxcnn *lp)
+{
+	return -EINVAL;
+}
+#endif
+
+static int arcxcnn_probe(struct i2c_client *cl, const struct i2c_device_id *id)
+{
+	struct arcxcnn *lp;
+	int ret;
+	u8 regval;
+	u16 chipid;
+
+	if (!i2c_check_functionality(cl->adapter, I2C_FUNC_SMBUS_BYTE_DATA))
+		return -EIO;
+
+	lp = devm_kzalloc(&cl->dev, sizeof(*lp), GFP_KERNEL);
+	if (!lp)
+		return -ENOMEM;
+
+	lp->client = cl;
+	lp->dev = &cl->dev;
+	lp->chip_id = id->driver_data;
+	lp->pdata = dev_get_platdata(&cl->dev);
+
+	if (!lp->pdata) {
+		lp->pdata = devm_kzalloc(lp->dev,
+				sizeof(*lp->pdata), GFP_KERNEL);
+		if (!lp->pdata)
+			return -ENOMEM;
+
+		/* no platform data, parse the device-tree for info.  if there
+		 * is no device tree entry, we are being told we exist because
+		 * user-land said so, so make up the info we need
+		 */
+		ret = arcxcnn_parse_dt(lp);
+		if (ret < 0) {
+			/* no device tree, use defaults based on module params
+			 */
+			lp->pdata->led_config_0_set = false;
+			lp->pdata->led_config_1_set = false;
+			lp->pdata->dim_freq_set = false;
+			lp->pdata->comp_config_set = false;
+			lp->pdata->filter_config_set = false;
+			lp->pdata->trim_config_set = false;
+
+			lp->pdata->name = NULL;
+			lp->pdata->initial_brightness = s_ibright;
+			lp->pdata->led_str = s_iledstr;
+		}
+	}
+
+	if (lp->pdata->dim_freq_set)
+		lp->mode = PWM_BASED;
+	else
+		lp->mode = REGISTER_BASED;
+
+	i2c_set_clientdata(cl, lp);
+
+	/* read device ID */
+	regval = arcxcnn_read_byte(lp, 0x1E);
+	chipid = regval;
+	chipid <<= 8;
+	regval = arcxcnn_read_byte(lp, 0x1F);
+	chipid |= regval;
+
+	/* make sure it belongs to this driver
+	 * TODO - handle specific ids
+	 */
+	if (chipid != 0x02A5) {
+		#if 1
+		dev_info(&cl->dev, "Chip Id is %04X\n", chipid);
+		#else
+		dev_err(&cl->dev, "%04X is not ARC2C\n", chipid);
+		return -ENODEV;
+		#endif
+	}
+	/* reset the device */
+	arcxcnn_write_byte(lp, ARCXCNN_CMD, ARCXCNN_CMD_RESET);
+
+	/* set initial brightness */
+	arcxcnn_set_brightness(lp, lp->pdata->initial_brightness);
+
+	/* if fadectrl set in DT, set the value directly, else leave default */
+	if (lp->pdata->led_config_0_set)
+		arcxcnn_write_byte(lp, ARCXCNN_FADECTRL,
+			lp->pdata->led_config_0);
+
+	/* if iled config set in DT, set the value, else internal mode */
+	if (lp->pdata->led_config_1_set)
+		arcxcnn_write_byte(lp, ARCXCNN_ILED_CONFIG,
+			lp->pdata->led_config_1);
+	else
+		arcxcnn_write_byte(lp, ARCXCNN_ILED_CONFIG, 0x57);
+
+	/* other misc DT settings */
+	if (lp->pdata->dim_freq_set)
+		arcxcnn_write_byte(lp, ARCXCNN_FADECTRL, lp->pdata->dim_freq);
+	if (lp->pdata->comp_config_set)
+		arcxcnn_write_byte(lp, ARCXCNN_COMP_CONFIG,
+			lp->pdata->comp_config);
+	if (lp->pdata->filter_config_set)
+		arcxcnn_write_byte(lp, ARCXCNN_FILT_CONFIG,
+			lp->pdata->filter_config);
+	if (lp->pdata->trim_config_set)
+		arcxcnn_write_byte(lp, ARCXCNN_IMAXTUNE,
+			lp->pdata->trim_config);
+
+	/* set initial LED Strings */
+	arcxcnn_update_bit(lp, ARCXCNN_LEDEN,
+		ARCXCNN_LEDEN_MASK, lp->pdata->led_str);
+
+	snprintf(lp->chipname, sizeof(lp->chipname),
+		"%s-%04X", id->name, chipid);
+
+	ret = arcxcnn_backlight_register(lp);
+	if (ret) {
+		dev_err(lp->dev,
+			"failed to register backlight. err: %d\n", ret);
+		return ret;
+	}
+
+	ret = sysfs_create_group(&lp->dev->kobj, &arcxcnn_attr_group);
+	if (ret) {
+		dev_err(lp->dev, "failed to register sysfs. err: %d\n", ret);
+		return ret;
+	}
+
+	backlight_update_status(lp->bl);
+	return 0;
+}
+
+static int arcxcnn_remove(struct i2c_client *cl)
+{
+	struct arcxcnn *lp = i2c_get_clientdata(cl);
+
+	if (!s_no_reset_on_remove) {
+		/* disable all strings */
+		arcxcnn_write_byte(lp, ARCXCNN_LEDEN, 0x00);
+		/* reset the device */
+		arcxcnn_write_byte(lp, ARCXCNN_CMD, ARCXCNN_CMD_RESET);
+	}
+	lp->bl->props.brightness = 0;
+	backlight_update_status(lp->bl);
+	if (lp->supply)
+		regulator_disable(lp->supply);
+	sysfs_remove_group(&lp->dev->kobj, &arcxcnn_attr_group);
+
+	return 0;
+}
+
+static const struct of_device_id arcxcnn_dt_ids[] = {
+	{ .compatible = "arc,arc2c0608" },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, arcxcnn_dt_ids);
+
+/* Note that the device/chip ID is not fixed in silicon so
+ * auto-probing of these devices on the bus is most likely
+ * not possible, use device tree to set i2c bus address
+ */
+static const struct i2c_device_id arcxcnn_ids[] = {
+	{"arc2c0608", ARC2C0608},
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, arcxcnn_ids);
+
+static struct i2c_driver arcxcnn_driver = {
+	.driver = {
+		   .name = "arcxcnn_bl",
+		   .of_match_table = of_match_ptr(arcxcnn_dt_ids),
+		   },
+	.probe = arcxcnn_probe,
+	.remove = arcxcnn_remove,
+	.id_table = arcxcnn_ids,
+};
+
+module_i2c_driver(arcxcnn_driver);
+
+MODULE_LICENSE("GPL v2");
+MODULE_AUTHOR("Brian Dodge <bdodge09@outlook.com>");
+MODULE_DESCRIPTION("ARCXCNN Backlight driver");
diff --git a/include/linux/i2c/arcxcnn.h b/include/linux/i2c/arcxcnn.h
new file mode 100644
index 0000000..1c681dd
--- /dev/null
+++ b/include/linux/i2c/arcxcnn.h
@@ -0,0 +1,67 @@
+/*
+ * Backlight driver for ArcticSand ARC2C0608 Backlight Devices
+ *
+ * Copyright 2016 ArcticSand, Inc.
+ *
+ * Licensed under the GPL-2 or later.
+ */
+
+#ifndef _ARCXCNN_H
+#define _ARCXCNN_H
+
+enum arcxcnn_chip_id {
+	ARC2C0608
+};
+
+enum arcxcnn_brightness_source {
+	ARCXCNN_PWM_ONLY,
+	ARCXCNN_I2C_ONLY = 2,
+};
+
+#define ARCXCNN_MAX_PROGENTRIES	48	/* max a/v pairs for custom */
+
+/**
+ * struct arcxcnn_platform_data
+ * @name : Backlight driver name. If it is not defined, default name is set.
+ * @initial_brightness : initial value of backlight brightness
+ * @led_str	 : initial LED string enables, upper bit is global on/off
+ * @led_config_0 : fading speed (period between intensity steps)
+ * @led_config_1 : misc settings, see datasheet
+ * @dim_freq	 : pwm dimming frequency if in pwm mode
+ * @comp_config	 : misc config, see datasheet
+ * @filter_config: RC/PWM filter config, see datasheet
+ * @trim_config	 : full scale current trim, see datasheet
+ * @led_config_0_set	: the value in led_config_0 is valid
+ * @led_config_1_set	: the value in led_config_1 is valid
+ * @dim_freq_set	: the value in dim_freq is valid
+ * @comp_config_set	: the value in comp_config is valid
+ * @filter_config_set	: the value in filter_config is valid
+ * @trim_config_set	: the value in trim_config is valid
+ *
+ * the _set flags are used to indicate that the value was explicitly set
+ * in the device tree or platform data. settings not set are left as default
+ * power-on default values of the chip except for led_str and led_config_1
+ * which are set by the driver (led_str is specified indirectly in the
+ * device tree via "led-sources")
+ */
+struct arcxcnn_platform_data {
+	const char *name;
+	u16 initial_brightness;
+	u8	led_str;
+
+	u8	led_config_0;
+	u8	led_config_1;
+	u8	dim_freq;
+	u8	comp_config;
+	u8	filter_config;
+	u8	trim_config;
+
+	bool	led_config_0_set;
+	bool	led_config_1_set;
+	bool	dim_freq_set;
+	bool	comp_config_set;
+	bool	filter_config_set;
+	bool	trim_config_set;
+};
+
+#endif
-- 
2.7.4

[PATCH 1/2] backlight: arcxcnn: add support for ArticSand devices

[Olimpiu Dejeu]

Resubmition of arcxcnn backliught driver adding devicetree entries
 for all registers

Signed-off-by: Olimpiu Dejeu <olimpiu@arcticsand.com>

---
 drivers/video/backlight/Kconfig      |   7 +
 drivers/video/backlight/Makefile     |   1 +
 drivers/video/backlight/arcxcnn_bl.c | 541 +++++++++++++++++++++++++++++++++++
 include/linux/i2c/arcxcnn.h          |  67 +++++
 4 files changed, 616 insertions(+)
 create mode 100644 drivers/video/backlight/arcxcnn_bl.c
 create mode 100644 include/linux/i2c/arcxcnn.h

diff --git a/drivers/video/backlight/Kconfig b/drivers/video/backlight/Kconfig
index 5ffa4b4..4e1d2ad 100644
--- a/drivers/video/backlight/Kconfig
+++ b/drivers/video/backlight/Kconfig
@@ -460,6 +460,13 @@ config BACKLIGHT_BD6107
 	help
 	  If you have a Rohm BD6107 say Y to enable the backlight driver.
 
+config BACKLIGHT_ARCXCNN
+	tristate "Backlight driver for the Arctic Sands ARCxCnnnn family"
+	depends on I2C
+	help
+	  If you have an ARCxCnnnn family backlight say Y to enable
+	  the backlight driver.
+
 endif # BACKLIGHT_CLASS_DEVICE
 
 endif # BACKLIGHT_LCD_SUPPORT
diff --git a/drivers/video/backlight/Makefile b/drivers/video/backlight/Makefile
index 16ec534..8905129 100644
--- a/drivers/video/backlight/Makefile
+++ b/drivers/video/backlight/Makefile
@@ -55,3 +55,4 @@ obj-$(CONFIG_BACKLIGHT_SKY81452)	+= sky81452-backlight.o
 obj-$(CONFIG_BACKLIGHT_TOSA)		+= tosa_bl.o
 obj-$(CONFIG_BACKLIGHT_TPS65217)	+= tps65217_bl.o
 obj-$(CONFIG_BACKLIGHT_WM831X)		+= wm831x_bl.o
+obj-$(CONFIG_BACKLIGHT_ARCXCNN) 	+= arcxcnn_bl.o
diff --git a/drivers/video/backlight/arcxcnn_bl.c b/drivers/video/backlight/arcxcnn_bl.c
new file mode 100644
index 0000000..1dad680
--- /dev/null
+++ b/drivers/video/backlight/arcxcnn_bl.c
@@ -0,0 +1,541 @@
+/*
+ * Backlight driver for ArcticSand ARC_X_C_0N_0N Devices
+ *
+ * Copyright 2016 ArcticSand, Inc.
+ *
+ * Licensed under the GPL-2 or later.
+ */
+
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/i2c.h>
+#include <linux/backlight.h>
+#include <linux/err.h>
+#include <linux/of.h>
+#include <linux/pwm.h>
+#include <linux/regulator/consumer.h>
+
+#include "linux/i2c/arcxcnn.h"
+
+#define ARCXCNN_CMD		(0x00)  /* Command Register */
+#define ARCXCNN_CMD_STDBY	(0x80)	/* I2C Standby */
+#define ARCXCNN_CMD_RESET	(0x40)	/* Reset */
+#define ARCXCNN_CMD_BOOST	(0x10)	/* Boost */
+#define ARCXCNN_CMD_OVP_MASK	(0x0C)	/* --- Over Voltage Threshold */
+#define ARCXCNN_CMD_OVP_XXV	(0x0C)	/* <rsvrd> Over Voltage Threshold */
+#define ARCXCNN_CMD_OVP_20V	(0x08)	/* 20v Over Voltage Threshold */
+#define ARCXCNN_CMD_OVP_24V	(0x04)	/* 24v Over Voltage Threshold */
+#define ARCXCNN_CMD_OVP_31V	(0x00)	/* 31.4v Over Voltage Threshold */
+#define ARCXCNN_CMD_EXT_COMP	(0x01)	/* part (0) or full (1) external comp */
+
+#define ARCXCNN_CONFIG	(0x01)  /* Configuration */
+#define ARCXCNN_STATUS1	(0x02)  /* Status 1 */
+#define ARCXCNN_STATUS2	(0x03)  /* Status 2 */
+#define ARCXCNN_FADECTRL	(0x04)  /* Fading Control */
+#define ARCXCNN_ILED_CONFIG	(0x05)  /* ILED Configuration */
+
+#define ARCXCNN_LEDEN		(0x06)  /* LED Enable Register */
+#define ARCXCNN_LEDEN_ISETEXT	(0x80)	/* Full-scale current set externally */
+#define ARCXCNN_LEDEN_MASK	(0x3F)	/* LED string enables */
+#define ARCXCNN_LEDEN_LED1	(0x01)
+#define ARCXCNN_LEDEN_LED2	(0x02)
+#define ARCXCNN_LEDEN_LED3	(0x04)
+#define ARCXCNN_LEDEN_LED4	(0x08)
+#define ARCXCNN_LEDEN_LED5	(0x10)
+#define ARCXCNN_LEDEN_LED6	(0x20)
+
+#define ARCXCNN_WLED_ISET_LSB	(0x07)  /* LED ISET LSB (in upper nibble) */
+#define ARCXCNN_WLED_ISET_MSB	(0x08)  /* LED ISET MSB (8 bits) */
+
+#define ARCXCNN_DIMFREQ		(0x09)
+#define ARCXCNN_COMP_CONFIG	(0x0A)
+#define ARCXCNN_FILT_CONFIG	(0x0B)
+#define ARCXCNN_IMAXTUNE	(0x0C)
+
+#define DEFAULT_BL_NAME		"arctic_bl"
+#define MAX_BRIGHTNESS		4095
+
+static int s_no_reset_on_remove;
+module_param_named(noreset, s_no_reset_on_remove, int, 0644);
+MODULE_PARM_DESC(noreset, "No reset on module removal");
+
+static int s_ibright = 60;
+module_param_named(ibright, s_ibright, int, 0644);
+MODULE_PARM_DESC(ibright, "Initial brightness (when no plat data)");
+
+static int s_iledstr = 0x3F;
+module_param_named(iledstr, s_iledstr, int, 0644);
+MODULE_PARM_DESC(iledstr, "Initial LED String (when no plat data)");
+
+static int s_retries = 2; /* 1 == only one try */
+module_param_named(retries, s_retries, int, 0644);
+MODULE_PARM_DESC(retries, "I2C retries attempted");
+
+enum arcxcnn_brightness_ctrl_mode {
+	PWM_BASED = 1,
+	REGISTER_BASED,
+};
+
+struct arcxcnn;
+
+struct arcxcnn {
+	char chipname[64];
+	enum arcxcnn_chip_id chip_id;
+	enum arcxcnn_brightness_ctrl_mode mode;
+	struct i2c_client *client;
+	struct backlight_device *bl;
+	struct device *dev;
+	struct arcxcnn_platform_data *pdata;
+	struct pwm_device *pwm;
+	struct regulator *supply;	/* regulator for VDD input */
+};
+
+static int arcxcnn_write_byte(struct arcxcnn *lp, u8 reg, u8 data)
+{
+	s32 ret = -1;
+	int att;
+
+	for (att = 0; att < s_retries; att++) {
+		ret = i2c_smbus_write_byte_data(lp->client, reg, data);
+		if (ret >= 0)
+			return 0;
+	}
+	return ret;
+}
+
+static u8 arcxcnn_read_byte(struct arcxcnn *lp, u8 reg)
+{
+	int val;
+	int att;
+
+	for (att = 0; att < s_retries; att++) {
+		val = i2c_smbus_read_byte_data(lp->client, reg);
+		if (val >= 0)
+			return (u8)val;
+	}
+	return 0;
+}
+
+static int arcxcnn_update_bit(struct arcxcnn *lp, u8 reg, u8 mask, u8 data)
+{
+	int ret, att;
+	u8 tmp;
+
+	for (att = 0, ret = -1; att < s_retries; att++) {
+		ret = i2c_smbus_read_byte_data(lp->client, reg);
+		if (ret >= 0)
+			break;
+	}
+	if (ret < 0) {
+		dev_err(lp->dev, "failed to read 0x%.2x\n", reg);
+		return ret;
+	}
+
+	tmp = (u8)ret;
+	tmp &= ~mask;
+	tmp |= data & mask;
+
+	return arcxcnn_write_byte(lp, reg, tmp);
+}
+
+static int arcxcnn_set_brightness(struct arcxcnn *lp, u32 brightness)
+{
+	int ret;
+	u8 val;
+
+	val = (brightness & 0xF) << 4;
+	ret = arcxcnn_write_byte(lp, ARCXCNN_WLED_ISET_LSB, val);
+	if (ret < 0)
+		return ret;
+	val = (brightness >> 4);
+	ret = arcxcnn_write_byte(lp, ARCXCNN_WLED_ISET_MSB, val);
+	return ret;
+}
+
+static int arcxcnn_bl_update_status(struct backlight_device *bl)
+{
+	struct arcxcnn *lp = bl_get_data(bl);
+	u32 brightness = bl->props.brightness;
+
+	if (bl->props.state & (BL_CORE_SUSPENDED | BL_CORE_FBBLANK))
+		brightness = 0;
+
+	/* set brightness */
+	if (lp->mode == PWM_BASED)
+		; /* via pwm */
+	else if (lp->mode == REGISTER_BASED)
+		arcxcnn_set_brightness(lp, brightness);
+
+	/* set power-on/off/save modes */
+	if (bl->props.power == 0)
+		/* take out of standby */
+		arcxcnn_update_bit(lp, ARCXCNN_CMD, ARCXCNN_CMD_STDBY, 0);
+	else
+		/* 1-3 == power save, 4 = off
+		 * place in low-power standby mode
+		 */
+		arcxcnn_update_bit(lp, ARCXCNN_CMD,
+				ARCXCNN_CMD_STDBY, ARCXCNN_CMD_STDBY);
+	return 0;
+}
+
+static const struct backlight_ops arcxcnn_bl_ops = {
+	.options = BL_CORE_SUSPENDRESUME,
+	.update_status = arcxcnn_bl_update_status,
+};
+
+static int arcxcnn_backlight_register(struct arcxcnn *lp)
+{
+	struct backlight_device *bl;
+	struct backlight_properties props;
+	struct arcxcnn_platform_data *pdata = lp->pdata;
+	const char *name = pdata->name ? : DEFAULT_BL_NAME;
+
+	memset(&props, 0, sizeof(props));
+	props.type = BACKLIGHT_PLATFORM;
+	props.max_brightness = MAX_BRIGHTNESS;
+
+	if (pdata->initial_brightness > props.max_brightness)
+		pdata->initial_brightness = props.max_brightness;
+
+	props.brightness = pdata->initial_brightness;
+
+	bl = devm_backlight_device_register(lp->dev, name, lp->dev, lp,
+				       &arcxcnn_bl_ops, &props);
+	if (IS_ERR(bl))
+		return PTR_ERR(bl);
+
+	lp->bl = bl;
+
+	return 0;
+}
+
+static ssize_t arcxcnn_get_chip_id(struct device *dev,
+		struct device_attribute *attr, char *buf)
+{
+	struct arcxcnn *lp = dev_get_drvdata(dev);
+
+	return scnprintf(buf, PAGE_SIZE, "%s\n", lp->chipname);
+}
+
+static ssize_t arcxcnn_get_led_str(struct device *dev,
+		struct device_attribute *attr, char *buf)
+{
+	struct arcxcnn *lp = dev_get_drvdata(dev);
+
+	return scnprintf(buf, PAGE_SIZE, "%02X\n", lp->pdata->led_str);
+}
+
+static ssize_t arcxcnn_set_led_str(struct device *dev,
+		struct device_attribute *attr, const char *buf, size_t len)
+{
+	struct arcxcnn *lp = dev_get_drvdata(dev);
+	unsigned long ledstr;
+
+	if (kstrtoul(buf, 0, &ledstr))
+		return 0;
+
+	if (ledstr != lp->pdata->led_str) {
+		/* don't allow 0 for ledstr, use power to turn all off */
+		if (ledstr == 0)
+			return 0;
+		lp->pdata->led_str = ledstr & 0x3F;
+		arcxcnn_update_bit(lp, ARCXCNN_LEDEN,
+			ARCXCNN_LEDEN_MASK, lp->pdata->led_str);
+	}
+	return len;
+}
+
+static ssize_t arcxcnn_get_bl_ctl_mode(struct device *dev,
+	     struct device_attribute *attr, char *buf)
+{
+	struct arcxcnn *lp = dev_get_drvdata(dev);
+	char *strmode = NULL;
+
+	if (lp->mode == PWM_BASED)
+		strmode = "pwm based";
+	else if (lp->mode == REGISTER_BASED)
+		strmode = "register based";
+
+	return scnprintf(buf, PAGE_SIZE, "%s\n", strmode);
+}
+
+static DEVICE_ATTR(chip_id, 0444, arcxcnn_get_chip_id, NULL);
+static DEVICE_ATTR(led_str, 0664, arcxcnn_get_led_str, arcxcnn_set_led_str);
+static DEVICE_ATTR(bl_ctl_mode, 0444, arcxcnn_get_bl_ctl_mode, NULL);
+
+static struct attribute *arcxcnn_attributes[] = {
+	&dev_attr_chip_id.attr,
+	&dev_attr_led_str.attr,
+	&dev_attr_bl_ctl_mode.attr,
+	NULL,
+};
+
+static const struct attribute_group arcxcnn_attr_group = {
+	.attrs = arcxcnn_attributes,
+};
+
+#ifdef CONFIG_OF
+static int arcxcnn_parse_dt(struct arcxcnn *lp)
+{
+	struct device *dev = lp->dev;
+	struct device_node *node = dev->of_node;
+	u32 prog_val, num_entry, sources[6];
+	int ret;
+
+	if (!node) {
+		dev_err(dev, "no platform data.\n");
+		return -EINVAL;
+	}
+	lp->pdata->led_config_0_set = false;
+	lp->pdata->led_config_1_set = false;
+	lp->pdata->dim_freq_set = false;
+	lp->pdata->comp_config_set = false;
+	lp->pdata->filter_config_set = false;
+	lp->pdata->trim_config_set = false;
+
+	ret = of_property_read_string(node, "label", &lp->pdata->name);
+	if (ret < 0)
+		lp->pdata->name = NULL;
+
+	ret = of_property_read_u32(node, "default-brightness", &prog_val);
+	if (ret < 0)
+		prog_val = s_ibright;
+	lp->pdata->initial_brightness = prog_val;
+	if (lp->pdata->initial_brightness > MAX_BRIGHTNESS)
+		lp->pdata->initial_brightness = MAX_BRIGHTNESS;
+
+	ret = of_property_read_u32(node, "arcticsand,led-config-0", &prog_val);
+	if (ret == 0) {
+		lp->pdata->led_config_0 = (u8)prog_val;
+		lp->pdata->led_config_0_set = true;
+	}
+	ret = of_property_read_u32(node, "arcticsand,led-config-1", &prog_val);
+	if (ret == 0) {
+		lp->pdata->led_config_1 = (u8)prog_val;
+		lp->pdata->led_config_1_set = true;
+	}
+	ret = of_property_read_u32(node, "arcticsand,dim-freq", &prog_val);
+	if (ret == 0) {
+		lp->pdata->dim_freq = (u8)prog_val;
+		lp->pdata->dim_freq_set = true;
+	}
+	ret = of_property_read_u32(node, "arcticsand,comp-config", &prog_val);
+	if (ret == 0) {
+		lp->pdata->comp_config = (u8)prog_val;
+		lp->pdata->comp_config_set = true;
+	}
+	ret = of_property_read_u32(node, "arcticsand,filter-config", &prog_val);
+	if (ret == 0) {
+		lp->pdata->filter_config = (u8)prog_val;
+		lp->pdata->filter_config_set = true;
+	}
+	ret = of_property_read_u32(node, "arcticsand,trim-config", &prog_val);
+	if (ret == 0) {
+		lp->pdata->trim_config = (u8)prog_val;
+		lp->pdata->trim_config_set = true;
+	}
+	ret = of_property_count_u32_elems(node, "led-sources");
+	if (ret < 0)
+		lp->pdata->led_str = 0x3F;
+	else {
+		num_entry = ret;
+		if (num_entry > 6)
+			num_entry = 6;
+
+		ret = of_property_read_u32_array(node, "led-sources", sources,
+					num_entry);
+		if (ret < 0) {
+			dev_err(dev, "led-sources node is invalid.\n");
+			return -EINVAL;
+		}
+
+		lp->pdata->led_str = 0;
+		while (num_entry > 0)
+			lp->pdata->led_str |= (1 << sources[--num_entry]);
+	}
+	return 0;
+}
+#else
+static int arcxcnn_parse_dt(struct arcxcnn *lp)
+{
+	return -EINVAL;
+}
+#endif
+
+static int arcxcnn_probe(struct i2c_client *cl, const struct i2c_device_id *id)
+{
+	struct arcxcnn *lp;
+	int ret;
+	u8 regval;
+	u16 chipid;
+
+	if (!i2c_check_functionality(cl->adapter, I2C_FUNC_SMBUS_BYTE_DATA))
+		return -EIO;
+
+	lp = devm_kzalloc(&cl->dev, sizeof(*lp), GFP_KERNEL);
+	if (!lp)
+		return -ENOMEM;
+
+	lp->client = cl;
+	lp->dev = &cl->dev;
+	lp->chip_id = id->driver_data;
+	lp->pdata = dev_get_platdata(&cl->dev);
+
+	if (!lp->pdata) {
+		lp->pdata = devm_kzalloc(lp->dev,
+				sizeof(*lp->pdata), GFP_KERNEL);
+		if (!lp->pdata)
+			return -ENOMEM;
+
+		/* no platform data, parse the device-tree for info.  if there
+		 * is no device tree entry, we are being told we exist because
+		 * user-land said so, so make up the info we need
+		 */
+		ret = arcxcnn_parse_dt(lp);
+		if (ret < 0) {
+			/* no device tree, use defaults based on module params
+			 */
+			lp->pdata->led_config_0_set = false;
+			lp->pdata->led_config_1_set = false;
+			lp->pdata->dim_freq_set = false;
+			lp->pdata->comp_config_set = false;
+			lp->pdata->filter_config_set = false;
+			lp->pdata->trim_config_set = false;
+
+			lp->pdata->name = NULL;
+			lp->pdata->initial_brightness = s_ibright;
+			lp->pdata->led_str = s_iledstr;
+		}
+	}
+
+	if (lp->pdata->dim_freq_set)
+		lp->mode = PWM_BASED;
+	else
+		lp->mode = REGISTER_BASED;
+
+	i2c_set_clientdata(cl, lp);
+
+	/* read device ID */
+	regval = arcxcnn_read_byte(lp, 0x1E);
+	chipid = regval;
+	chipid <<= 8;
+	regval = arcxcnn_read_byte(lp, 0x1F);
+	chipid |= regval;
+
+	/* make sure it belongs to this driver
+	 * TODO - handle specific ids
+	 */
+	if (chipid != 0x02A5) {
+		#if 1
+		dev_info(&cl->dev, "Chip Id is %04X\n", chipid);
+		#else
+		dev_err(&cl->dev, "%04X is not ARC2C\n", chipid);
+		return -ENODEV;
+		#endif
+	}
+	/* reset the device */
+	arcxcnn_write_byte(lp, ARCXCNN_CMD, ARCXCNN_CMD_RESET);
+
+	/* set initial brightness */
+	arcxcnn_set_brightness(lp, lp->pdata->initial_brightness);
+
+	/* if fadectrl set in DT, set the value directly, else leave default */
+	if (lp->pdata->led_config_0_set)
+		arcxcnn_write_byte(lp, ARCXCNN_FADECTRL,
+			lp->pdata->led_config_0);
+
+	/* if iled config set in DT, set the value, else internal mode */
+	if (lp->pdata->led_config_1_set)
+		arcxcnn_write_byte(lp, ARCXCNN_ILED_CONFIG,
+			lp->pdata->led_config_1);
+	else
+		arcxcnn_write_byte(lp, ARCXCNN_ILED_CONFIG, 0x57);
+
+	/* other misc DT settings */
+	if (lp->pdata->dim_freq_set)
+		arcxcnn_write_byte(lp, ARCXCNN_FADECTRL, lp->pdata->dim_freq);
+	if (lp->pdata->comp_config_set)
+		arcxcnn_write_byte(lp, ARCXCNN_COMP_CONFIG,
+			lp->pdata->comp_config);
+	if (lp->pdata->filter_config_set)
+		arcxcnn_write_byte(lp, ARCXCNN_FILT_CONFIG,
+			lp->pdata->filter_config);
+	if (lp->pdata->trim_config_set)
+		arcxcnn_write_byte(lp, ARCXCNN_IMAXTUNE,
+			lp->pdata->trim_config);
+
+	/* set initial LED Strings */
+	arcxcnn_update_bit(lp, ARCXCNN_LEDEN,
+		ARCXCNN_LEDEN_MASK, lp->pdata->led_str);
+
+	snprintf(lp->chipname, sizeof(lp->chipname),
+		"%s-%04X", id->name, chipid);
+
+	ret = arcxcnn_backlight_register(lp);
+	if (ret) {
+		dev_err(lp->dev,
+			"failed to register backlight. err: %d\n", ret);
+		return ret;
+	}
+
+	ret = sysfs_create_group(&lp->dev->kobj, &arcxcnn_attr_group);
+	if (ret) {
+		dev_err(lp->dev, "failed to register sysfs. err: %d\n", ret);
+		return ret;
+	}
+
+	backlight_update_status(lp->bl);
+	return 0;
+}
+
+static int arcxcnn_remove(struct i2c_client *cl)
+{
+	struct arcxcnn *lp = i2c_get_clientdata(cl);
+
+	if (!s_no_reset_on_remove) {
+		/* disable all strings */
+		arcxcnn_write_byte(lp, ARCXCNN_LEDEN, 0x00);
+		/* reset the device */
+		arcxcnn_write_byte(lp, ARCXCNN_CMD, ARCXCNN_CMD_RESET);
+	}
+	lp->bl->props.brightness = 0;
+	backlight_update_status(lp->bl);
+	if (lp->supply)
+		regulator_disable(lp->supply);
+	sysfs_remove_group(&lp->dev->kobj, &arcxcnn_attr_group);
+
+	return 0;
+}
+
+static const struct of_device_id arcxcnn_dt_ids[] = {
+	{ .compatible = "arc,arc2c0608" },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, arcxcnn_dt_ids);
+
+/* Note that the device/chip ID is not fixed in silicon so
+ * auto-probing of these devices on the bus is most likely
+ * not possible, use device tree to set i2c bus address
+ */
+static const struct i2c_device_id arcxcnn_ids[] = {
+	{"arc2c0608", ARC2C0608},
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, arcxcnn_ids);
+
+static struct i2c_driver arcxcnn_driver = {
+	.driver = {
+		   .name = "arcxcnn_bl",
+		   .of_match_table = of_match_ptr(arcxcnn_dt_ids),
+		   },
+	.probe = arcxcnn_probe,
+	.remove = arcxcnn_remove,
+	.id_table = arcxcnn_ids,
+};
+
+module_i2c_driver(arcxcnn_driver);
+
+MODULE_LICENSE("GPL v2");
+MODULE_AUTHOR("Brian Dodge <bdodge09@outlook.com>");
+MODULE_DESCRIPTION("ARCXCNN Backlight driver");
diff --git a/include/linux/i2c/arcxcnn.h b/include/linux/i2c/arcxcnn.h
new file mode 100644
index 0000000..1c681dd
--- /dev/null
+++ b/include/linux/i2c/arcxcnn.h
@@ -0,0 +1,67 @@
+/*
+ * Backlight driver for ArcticSand ARC2C0608 Backlight Devices
+ *
+ * Copyright 2016 ArcticSand, Inc.
+ *
+ * Licensed under the GPL-2 or later.
+ */
+
+#ifndef _ARCXCNN_H
+#define _ARCXCNN_H
+
+enum arcxcnn_chip_id {
+	ARC2C0608
+};
+
+enum arcxcnn_brightness_source {
+	ARCXCNN_PWM_ONLY,
+	ARCXCNN_I2C_ONLY = 2,
+};
+
+#define ARCXCNN_MAX_PROGENTRIES	48	/* max a/v pairs for custom */
+
+/**
+ * struct arcxcnn_platform_data
+ * @name : Backlight driver name. If it is not defined, default name is set.
+ * @initial_brightness : initial value of backlight brightness
+ * @led_str	 : initial LED string enables, upper bit is global on/off
+ * @led_config_0 : fading speed (period between intensity steps)
+ * @led_config_1 : misc settings, see datasheet
+ * @dim_freq	 : pwm dimming frequency if in pwm mode
+ * @comp_config	 : misc config, see datasheet
+ * @filter_config: RC/PWM filter config, see datasheet
+ * @trim_config	 : full scale current trim, see datasheet
+ * @led_config_0_set	: the value in led_config_0 is valid
+ * @led_config_1_set	: the value in led_config_1 is valid
+ * @dim_freq_set	: the value in dim_freq is valid
+ * @comp_config_set	: the value in comp_config is valid
+ * @filter_config_set	: the value in filter_config is valid
+ * @trim_config_set	: the value in trim_config is valid
+ *
+ * the _set flags are used to indicate that the value was explicitly set
+ * in the device tree or platform data. settings not set are left as default
+ * power-on default values of the chip except for led_str and led_config_1
+ * which are set by the driver (led_str is specified indirectly in the
+ * device tree via "led-sources")
+ */
+struct arcxcnn_platform_data {
+	const char *name;
+	u16 initial_brightness;
+	u8	led_str;
+
+	u8	led_config_0;
+	u8	led_config_1;
+	u8	dim_freq;
+	u8	comp_config;
+	u8	filter_config;
+	u8	trim_config;
+
+	bool	led_config_0_set;
+	bool	led_config_1_set;
+	bool	dim_freq_set;
+	bool	comp_config_set;
+	bool	filter_config_set;
+	bool	trim_config_set;
+};
+
+#endif
-- 
2.7.4

Re: [PATCH 1/2] backlight: arcxcnn: add support for ArticSand devices

[Mark Rutland]

On Thu, Sep 29, 2016 at 12:34:39PM -0400, Olimpiu Dejeu wrote:
> Resubmition of arcxcnn backliught driver adding definitions of the
>  internal registers of the chip. 

s/backliught/backlight/

[...]

> +#ifdef CONFIG_OF
> +static int arcxcnn_parse_dt(struct arcxcnn *lp)
> +{
> +	struct device *dev = lp->dev;
> +	struct device_node *node = dev->of_node;
> +	u32 prog_length, prog_val, num_entry, sources[6];
> +	int ret;
> +
> +	if (!node) {
> +		dev_err(dev, "no platform data.\n");
> +		return -EINVAL;
> +	}
> +	of_property_read_string(node, "label", &lp->pdata->name);
> +	of_property_read_u32(node, "default-brightness", &prog_val);
> +	lp->pdata->initial_brightness = prog_val;

You must check the return value of the of_ accessors. If there's no
default-brightness property in the DT, prog_val will be uninitialised here.

> +	of_property_read_u32(node, "pwm-period", &lp->pdata->period_ns);

This was not in the binding document.

> +	/* Fill program from platform data if defined
> +	*/
> +	lp->pdata->prog_entries = 0;
> +	prog_length = of_get_child_count(node);
> +	if (prog_length > 0) {
> +		struct device_node *child;
> +		u32 i = 0;
> +
> +		for_each_child_of_node(node, child) {
> +			if (i >= ARCXCNN_MAX_PROGENTRIES)
> +				break;
> +			of_property_read_u32(child, "reg", &prog_val);
> +			lp->pdata->prog_addr[i] = (u8)prog_val;
> +			of_property_read_u32(child, "val", &prog_val);
> +			lp->pdata->prog_data[i] = (u8)prog_val;
> +			i++;
> +		}
> +		lp->pdata->prog_entries = i;
> +	}

This was also not documented.

What is this? What is it used for? Why is it in the DT?

> +	/* playback program now that its all installed */
> +	for (i = 0; i < lp->pdata->prog_entries; i++) {
> +		arcxcnn_write_byte(lp, lp->pdata->prog_addr[i],
> +				lp->pdata->prog_data[i]);
> +		/*
> +		printk(KERN_ALERT "%02X, %02X\n",
> +			lp->pdata->prog_addr[i], lp->pdata->prog_data[i]);
> +		*/
> +	}

Why is it necessary to have an arbitrary register programming sequence? What
exactly varies between parts?

I don't think this is the right way to solve your problem.

Thanks,
Mark.

[PATCH 1/2] backlight: arcxcnn: add support for ArticSand devices

[Olimpiu Dejeu]

Resubmition of arcxcnn backliught driver adding definitions of the
 internal registers of the chip. 

Signed-off-by: Olimpiu Dejeu <olimpiu@arcticsand.com>

---
 drivers/video/backlight/Kconfig      |   7 +
 drivers/video/backlight/Makefile     |   1 +
 drivers/video/backlight/arcxcnn_bl.c | 527 +++++++++++++++++++++++++++++++++++
 include/linux/i2c/arcxcnn.h          |  41 +++
 4 files changed, 576 insertions(+)
 create mode 100644 drivers/video/backlight/arcxcnn_bl.c
 create mode 100644 include/linux/i2c/arcxcnn.h

diff --git a/drivers/video/backlight/Kconfig b/drivers/video/backlight/Kconfig
index 5ffa4b4..4e1d2ad 100644
--- a/drivers/video/backlight/Kconfig
+++ b/drivers/video/backlight/Kconfig
@@ -460,6 +460,13 @@ config BACKLIGHT_BD6107
 	help
 	  If you have a Rohm BD6107 say Y to enable the backlight driver.
 
+config BACKLIGHT_ARCXCNN
+	tristate "Backlight driver for the Arctic Sands ARCxCnnnn family"
+	depends on I2C
+	help
+	  If you have an ARCxCnnnn family backlight say Y to enable
+	  the backlight driver.
+
 endif # BACKLIGHT_CLASS_DEVICE
 
 endif # BACKLIGHT_LCD_SUPPORT
diff --git a/drivers/video/backlight/Makefile b/drivers/video/backlight/Makefile
index 16ec534..8905129 100644
--- a/drivers/video/backlight/Makefile
+++ b/drivers/video/backlight/Makefile
@@ -55,3 +55,4 @@ obj-$(CONFIG_BACKLIGHT_SKY81452)	+= sky81452-backlight.o
 obj-$(CONFIG_BACKLIGHT_TOSA)		+= tosa_bl.o
 obj-$(CONFIG_BACKLIGHT_TPS65217)	+= tps65217_bl.o
 obj-$(CONFIG_BACKLIGHT_WM831X)		+= wm831x_bl.o
+obj-$(CONFIG_BACKLIGHT_ARCXCNN) 	+= arcxcnn_bl.o
diff --git a/drivers/video/backlight/arcxcnn_bl.c b/drivers/video/backlight/arcxcnn_bl.c
new file mode 100644
index 0000000..da7d44e
--- /dev/null
+++ b/drivers/video/backlight/arcxcnn_bl.c
@@ -0,0 +1,527 @@
+/*
+ * Backlight driver for Arctic Sands ARC_X_C_0N_0N Devices
+ *
+ * Copyright 2016 Arctic Sands Inc.
+ *
+ * Licensed under the GPL-2 or later.
+ */
+
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/i2c.h>
+#include <linux/backlight.h>
+#include <linux/err.h>
+#include <linux/of.h>
+#include <linux/pwm.h>
+#include <linux/regulator/consumer.h>
+
+#include "linux/i2c/arcxcnn.h"
+
+#define ARCXCNN_CMD		(0x00)  /* Command Register */
+#define ARCXCNN_CMD_STDBY	(0x80)	/* I2C Standby */
+#define ARCXCNN_CMD_RESET	(0x40)	/* Reset */
+#define ARCXCNN_CMD_BOOST	(0x10)	/* Boost */
+#define ARCXCNN_CMD_OVP_MASK	(0x0C)	/* --- Over Voltage Threshold */
+#define ARCXCNN_CMD_OVP_XXV	(0x0C)	/* <rsvrd> Over Voltage Threshold */
+#define ARCXCNN_CMD_OVP_20V	(0x08)	/* 20v Over Voltage Threshold */
+#define ARCXCNN_CMD_OVP_24V	(0x04)	/* 24v Over Voltage Threshold */
+#define ARCXCNN_CMD_OVP_31V	(0x00)	/* 31.4v Over Voltage Threshold */
+#define ARCXCNN_CMD_EXT_COMP	(0x01)	/* part (0) or full (1) external comp */
+
+#define ARCXCNN_CONFIG	(0x01)  /* Configuration */
+#define ARCXCNN_STATUS1	(0x02)  /* Status 1 */
+#define ARCXCNN_STATUS2	(0x03)  /* Status 2 */
+#define ARCXCNN_FADECTRL	(0x04)  /* Fading Control */
+#define ARCXCNN_ILED_CONFIG	(0x05)  /* ILED Configuration */
+
+#define ARCXCNN_LEDEN		(0x06)  /* LED Enable Register */
+#define ARCXCNN_LEDEN_ISETEXT	(0x80)	/* Full-scale current set externally */
+#define ARCXCNN_LEDEN_MASK	(0x3F)	/* LED string enables */
+#define ARCXCNN_LEDEN_LED1	(0x01)
+#define ARCXCNN_LEDEN_LED2	(0x02)
+#define ARCXCNN_LEDEN_LED3	(0x04)
+#define ARCXCNN_LEDEN_LED4	(0x08)
+#define ARCXCNN_LEDEN_LED5	(0x10)
+#define ARCXCNN_LEDEN_LED6	(0x20)
+
+#define ARCXCNN_WLED_ISET_LSB	(0x07)  /* LED ISET LSB (in upper nibble) */
+#define ARCXCNN_WLED_ISET_MSB	(0x08)  /* LED ISET MSB (8 bits) */
+
+#define DEFAULT_BL_NAME		"arctic_bl"
+#define MAX_BRIGHTNESS		4095
+
+static int s_no_reset_on_remove;
+module_param_named(noreset, s_no_reset_on_remove, int, 0644);
+MODULE_PARM_DESC(noreset, "No reset on module removal");
+
+static int s_ibright = 60;
+module_param_named(ibright, s_ibright, int, 0644);
+MODULE_PARM_DESC(ibright, "Initial brightness (when no plat data)");
+
+static int s_iledstr = 0x3F;
+module_param_named(iledstr, s_iledstr, int, 0644);
+MODULE_PARM_DESC(iledstr, "Initial LED String (when no plat data)");
+
+static int s_retries = 2; /* 1 == only one try */
+module_param_named(retries, s_retries, int, 0644);
+MODULE_PARM_DESC(retries, "I2C retries attempted");
+
+enum arcxcnn_brightness_ctrl_mode {
+	PWM_BASED = 1,
+	REGISTER_BASED,
+};
+
+struct arcxcnn;
+
+struct arcxcnn {
+	char chipname[64];
+	enum arcxcnn_chip_id chip_id;
+	enum arcxcnn_brightness_ctrl_mode mode;
+	struct i2c_client *client;
+	struct backlight_device *bl;
+	struct device *dev;
+	struct arcxcnn_platform_data *pdata;
+	struct pwm_device *pwm;
+	struct regulator *supply;	/* regulator for VDD input */
+};
+
+static int arcxcnn_write_byte(struct arcxcnn *lp, u8 reg, u8 data)
+{
+	s32 ret = -1;
+	int att;
+
+	for (att = 0; att < s_retries; att++) {
+		ret = i2c_smbus_write_byte_data(lp->client, reg, data);
+		if (ret >= 0)
+			return 0;
+	}
+	return ret;
+}
+
+static u8 arcxcnn_read_byte(struct arcxcnn *lp, u8 reg)
+{
+	int val;
+	int att;
+
+	for (att = 0; att < s_retries; att++) {
+		val = i2c_smbus_read_byte_data(lp->client, reg);
+		if (val >= 0)
+			return (u8)val;
+	}
+	return 0;
+}
+
+static int arcxcnn_update_bit(struct arcxcnn *lp, u8 reg, u8 mask, u8 data)
+{
+	int ret, att;
+	u8 tmp;
+
+	for (att = 0, ret = -1; att < s_retries; att++) {
+		ret = i2c_smbus_read_byte_data(lp->client, reg);
+		if (ret >= 0)
+			break;
+	}
+	if (ret < 0) {
+		dev_err(lp->dev, "failed to read 0x%.2x\n", reg);
+		return ret;
+	}
+
+	tmp = (u8)ret;
+	tmp &= ~mask;
+	tmp |= data & mask;
+
+	return arcxcnn_write_byte(lp, reg, tmp);
+}
+
+static int arcxcnn_set_brightness(struct arcxcnn *lp, u32 brightness)
+{
+	int ret;
+	u8 val;
+
+	val = (brightness & 0xF) << 4;
+	ret = arcxcnn_write_byte(lp, ARCXCNN_WLED_ISET_LSB, val);
+	if (ret < 0)
+		return ret;
+	val = (brightness >> 4);
+	ret = arcxcnn_write_byte(lp, ARCXCNN_WLED_ISET_MSB, val);
+	return ret;
+}
+
+static void arcxcnn_pwm_ctrl(struct arcxcnn *lp, int br, int max_br)
+{
+	unsigned int period = lp->pdata->period_ns;
+	unsigned int duty = br * period / max_br;
+	struct pwm_device *pwm;
+
+	/* request pwm device with the consumer name */
+	if (!lp->pwm) {
+		pwm = devm_pwm_get(lp->dev, lp->chipname);
+		if (IS_ERR(pwm))
+			return;
+
+		lp->pwm = pwm;
+	}
+
+	pwm_config(lp->pwm, duty, period);
+	if (duty)
+		pwm_enable(lp->pwm);
+	else
+		pwm_disable(lp->pwm);
+}
+
+static int arcxcnn_bl_update_status(struct backlight_device *bl)
+{
+	struct arcxcnn *lp = bl_get_data(bl);
+	u32 brightness = bl->props.brightness;
+
+	if (bl->props.state & (BL_CORE_SUSPENDED | BL_CORE_FBBLANK))
+		brightness = 0;
+
+	/* set brightness */
+	if (lp->mode == PWM_BASED)
+		arcxcnn_pwm_ctrl(lp, brightness, bl->props.max_brightness);
+	else if (lp->mode == REGISTER_BASED)
+		arcxcnn_set_brightness(lp, brightness);
+
+	/* set power-on/off/save modes */
+	if (bl->props.power == 0)
+		/* take out of standby */
+		arcxcnn_update_bit(lp, ARCXCNN_CMD, ARCXCNN_CMD_STDBY, 0);
+	else
+		/* 1-3 == power save, 4 = off
+		 * place in low-power standby mode
+		 */
+		arcxcnn_update_bit(lp, ARCXCNN_CMD,
+				ARCXCNN_CMD_STDBY, ARCXCNN_CMD_STDBY);
+	return 0;
+}
+
+static const struct backlight_ops arcxcnn_bl_ops = {
+	.options = BL_CORE_SUSPENDRESUME,
+	.update_status = arcxcnn_bl_update_status,
+};
+
+static int arcxcnn_backlight_register(struct arcxcnn *lp)
+{
+	struct backlight_device *bl;
+	struct backlight_properties props;
+	struct arcxcnn_platform_data *pdata = lp->pdata;
+	const char *name = pdata->name ? : DEFAULT_BL_NAME;
+
+	memset(&props, 0, sizeof(props));
+	props.type = BACKLIGHT_PLATFORM;
+	props.max_brightness = MAX_BRIGHTNESS;
+
+	if (pdata->initial_brightness > props.max_brightness)
+		pdata->initial_brightness = props.max_brightness;
+
+	props.brightness = pdata->initial_brightness;
+
+	bl = devm_backlight_device_register(lp->dev, name, lp->dev, lp,
+				       &arcxcnn_bl_ops, &props);
+	if (IS_ERR(bl))
+		return PTR_ERR(bl);
+
+	lp->bl = bl;
+
+	return 0;
+}
+
+static ssize_t arcxcnn_get_chip_id(struct device *dev,
+		struct device_attribute *attr, char *buf)
+{
+	struct arcxcnn *lp = dev_get_drvdata(dev);
+
+	return scnprintf(buf, PAGE_SIZE, "%s\n", lp->chipname);
+}
+
+static ssize_t arcxcnn_get_led_str(struct device *dev,
+		struct device_attribute *attr, char *buf)
+{
+	struct arcxcnn *lp = dev_get_drvdata(dev);
+
+	return scnprintf(buf, PAGE_SIZE, "%02X\n", lp->pdata->ledstr);
+}
+
+static ssize_t arcxcnn_set_led_str(struct device *dev,
+		struct device_attribute *attr, const char *buf, size_t len)
+{
+	struct arcxcnn *lp = dev_get_drvdata(dev);
+	unsigned long ledstr;
+
+	if (kstrtoul(buf, 0, &ledstr))
+		return 0;
+
+	if (ledstr != lp->pdata->ledstr) {
+		/* don't allow 0 for ledstr, use power to turn all off */
+		if (ledstr == 0)
+			return 0;
+		lp->pdata->ledstr = ledstr & 0x3F;
+		arcxcnn_update_bit(lp, ARCXCNN_LEDEN,
+			ARCXCNN_LEDEN_MASK, lp->pdata->ledstr);
+	}
+	return len;
+}
+
+static ssize_t arcxcnn_get_bl_ctl_mode(struct device *dev,
+	     struct device_attribute *attr, char *buf)
+{
+	struct arcxcnn *lp = dev_get_drvdata(dev);
+	char *strmode = NULL;
+
+	if (lp->mode == PWM_BASED)
+		strmode = "pwm based";
+	else if (lp->mode == REGISTER_BASED)
+		strmode = "register based";
+
+	return scnprintf(buf, PAGE_SIZE, "%s\n", strmode);
+}
+
+static DEVICE_ATTR(chip_id, 0444, arcxcnn_get_chip_id, NULL);
+static DEVICE_ATTR(led_str, 0664, arcxcnn_get_led_str, arcxcnn_set_led_str);
+static DEVICE_ATTR(bl_ctl_mode, 0444, arcxcnn_get_bl_ctl_mode, NULL);
+
+static struct attribute *arcxcnn_attributes[] = {
+	&dev_attr_chip_id.attr,
+	&dev_attr_led_str.attr,
+	&dev_attr_bl_ctl_mode.attr,
+	NULL,
+};
+
+static const struct attribute_group arcxcnn_attr_group = {
+	.attrs = arcxcnn_attributes,
+};
+
+#ifdef CONFIG_OF
+static int arcxcnn_parse_dt(struct arcxcnn *lp)
+{
+	struct device *dev = lp->dev;
+	struct device_node *node = dev->of_node;
+	u32 prog_length, prog_val, num_entry, sources[6];
+	int ret;
+
+	if (!node) {
+		dev_err(dev, "no platform data.\n");
+		return -EINVAL;
+	}
+	of_property_read_string(node, "label", &lp->pdata->name);
+	of_property_read_u32(node, "default-brightness", &prog_val);
+	lp->pdata->initial_brightness = prog_val;
+	of_property_read_u32(node, "pwm-period", &lp->pdata->period_ns);
+
+	if (lp->pdata->initial_brightness > MAX_BRIGHTNESS)
+		lp->pdata->initial_brightness = MAX_BRIGHTNESS;
+
+	ret = of_property_count_u32_elems(node, "led-sources");
+	if (ret < 0) {
+		lp->pdata->ledstr = 0x3F;
+	} else {
+		num_entry = ret;
+		if (num_entry > 6)
+			num_entry = 6;
+
+		ret = of_property_read_u32_array(node, "led-sources", sources,
+					num_entry);
+		if (ret < 0) {
+			dev_err(dev, "led-sources node is invalid.\n");
+			return -EINVAL;
+		}
+
+		lp->pdata->ledstr = 0;
+		while (num_entry > 0)
+			lp->pdata->ledstr |= (1 << sources[--num_entry]);
+	}
+	/* Fill program from platform data if defined
+	*/
+	lp->pdata->prog_entries = 0;
+	prog_length = of_get_child_count(node);
+	if (prog_length > 0) {
+		struct device_node *child;
+		u32 i = 0;
+
+		for_each_child_of_node(node, child) {
+			if (i >= ARCXCNN_MAX_PROGENTRIES)
+				break;
+			of_property_read_u32(child, "reg", &prog_val);
+			lp->pdata->prog_addr[i] = (u8)prog_val;
+			of_property_read_u32(child, "val", &prog_val);
+			lp->pdata->prog_data[i] = (u8)prog_val;
+			i++;
+		}
+		lp->pdata->prog_entries = i;
+	}
+	return 0;
+}
+#else
+static int arcxcnn_parse_dt(struct arcxcnn *lp)
+{
+	return -EINVAL;
+}
+#endif
+
+static int arcxcnn_probe(struct i2c_client *cl, const struct i2c_device_id *id)
+{
+	struct arcxcnn *lp;
+	int ret;
+	u32 i;
+	u8 regval;
+	u16 chipid;
+
+	if (!i2c_check_functionality(cl->adapter, I2C_FUNC_SMBUS_BYTE_DATA))
+		return -EIO;
+
+	lp = devm_kzalloc(&cl->dev, sizeof(*lp), GFP_KERNEL);
+	if (!lp)
+		return -ENOMEM;
+
+	lp->client = cl;
+	lp->dev = &cl->dev;
+	lp->chip_id = id->driver_data;
+	lp->pdata = dev_get_platdata(&cl->dev);
+
+	if (!lp->pdata) {
+		lp->pdata = devm_kzalloc(lp->dev,
+				sizeof(*lp->pdata), GFP_KERNEL);
+		if (!lp->pdata)
+			return -ENOMEM;
+
+		/* no platform data, parse the device-tree for info.  if there
+		 * is no device tree entry, we are being told we exist because
+		 * user-land said so, so make up the info we need
+		 */
+		ret = arcxcnn_parse_dt(lp);
+		if (ret < 0) {
+			/* no device tree, use defaults based on parms
+			*/
+			lp->pdata->name = NULL;
+			lp->pdata->initial_brightness = s_ibright;
+			lp->pdata->ledstr = s_iledstr;
+			lp->pdata->period_ns = 0;
+			lp->pdata->prog_entries = 0;
+
+			/* example of prog use: uncomment to test
+			lp->pdata->prog_addr[0] = 0x06;
+			lp->pdata->prog_data[0] = 0x15;
+			lp->pdata->prog_entries = 1;
+			*/
+		}
+	}
+
+	if (lp->pdata->period_ns > 0)
+		lp->mode = PWM_BASED;
+	else
+		lp->mode = REGISTER_BASED;
+
+	i2c_set_clientdata(cl, lp);
+
+	/* read device ID */
+	regval = arcxcnn_read_byte(lp, 0x1E);
+	chipid = regval;
+	chipid <<= 8;
+	regval = arcxcnn_read_byte(lp, 0x1F);
+	chipid |= regval;
+
+	/* make sure it belongs to this driver
+	 * TODO - handle specific ids
+	 */
+	if (chipid != 0x02A5) {
+		#if 1
+		dev_info(&cl->dev, "Chip Id is %04X\n", chipid);
+		#else
+		dev_err(&cl->dev, "%04X is not ARC2C\n", chipid);
+		return -ENODEV;
+		#endif
+	}
+	/* reset the device */
+	arcxcnn_write_byte(lp, ARCXCNN_CMD, ARCXCNN_CMD_RESET);
+
+	/* set initial brightness */
+	arcxcnn_set_brightness(lp, lp->pdata->initial_brightness);
+
+	/* enable internal register mode for brightness */
+	arcxcnn_write_byte(lp, ARCXCNN_ILED_CONFIG, 0x57);
+
+	/* set initial LED Strings */
+	arcxcnn_update_bit(lp, ARCXCNN_LEDEN,
+		ARCXCNN_LEDEN_MASK, lp->pdata->ledstr);
+
+	snprintf(lp->chipname, sizeof(lp->chipname),
+			"%s-%04X", id->name, chipid);
+
+	ret = arcxcnn_backlight_register(lp);
+	if (ret) {
+		dev_err(lp->dev,
+			"failed to register backlight. err: %d\n", ret);
+		return ret;
+	}
+
+	ret = sysfs_create_group(&lp->dev->kobj, &arcxcnn_attr_group);
+	if (ret) {
+		dev_err(lp->dev, "failed to register sysfs. err: %d\n", ret);
+		return ret;
+	}
+
+	/* playback program now that its all installed */
+	for (i = 0; i < lp->pdata->prog_entries; i++) {
+		arcxcnn_write_byte(lp, lp->pdata->prog_addr[i],
+				lp->pdata->prog_data[i]);
+		/*
+		printk(KERN_ALERT "%02X, %02X\n",
+			lp->pdata->prog_addr[i], lp->pdata->prog_data[i]);
+		*/
+	}
+
+	backlight_update_status(lp->bl);
+	return 0;
+}
+
+static int arcxcnn_remove(struct i2c_client *cl)
+{
+	struct arcxcnn *lp = i2c_get_clientdata(cl);
+
+	if (!s_no_reset_on_remove) {
+		/* disable all strings */
+		arcxcnn_write_byte(lp, ARCXCNN_LEDEN, 0x00);
+		/* reset the device */
+		arcxcnn_write_byte(lp, ARCXCNN_CMD, ARCXCNN_CMD_RESET);
+	}
+	lp->bl->props.brightness = 0;
+	backlight_update_status(lp->bl);
+	if (lp->supply)
+		regulator_disable(lp->supply);
+	sysfs_remove_group(&lp->dev->kobj, &arcxcnn_attr_group);
+
+	return 0;
+}
+
+static const struct of_device_id arcxcnn_dt_ids[] = {
+	{ .compatible = "arc,arc2c0608" },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, arcxcnn_dt_ids);
+
+/* Note that the device/chip ID is not fixed in silicon so
+ * auto-probing of these devices on the bus is most likely
+ * not possible, use device tree to set i2c bus address
+ */
+static const struct i2c_device_id arcxcnn_ids[] = {
+	{"arc2c0608", ARC2C0608},
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, arcxcnn_ids);
+
+static struct i2c_driver arcxcnn_driver = {
+	.driver = {
+		   .name = "arcxcnn_bl",
+		   .of_match_table = of_match_ptr(arcxcnn_dt_ids),
+		   },
+	.probe = arcxcnn_probe,
+	.remove = arcxcnn_remove,
+	.id_table = arcxcnn_ids,
+};
+
+module_i2c_driver(arcxcnn_driver);
+
+MODULE_LICENSE("GPL v2");
+MODULE_AUTHOR("Brian Dodge <bdodge09@outlook.com>");
+MODULE_DESCRIPTION("ARCXCNN Backlight driver");
diff --git a/include/linux/i2c/arcxcnn.h b/include/linux/i2c/arcxcnn.h
new file mode 100644
index 0000000..0698f57
--- /dev/null
+++ b/include/linux/i2c/arcxcnn.h
@@ -0,0 +1,41 @@
+/*
+ * Backlight driver for Arctic Sands ARC2C0608 Backlight Devices
+ *
+ * Copyright 2016 Arctic Sands Inc.
+ *
+ * Licensed under the GPL-2 or later.
+ */
+
+#ifndef _ARCXCNN_H
+#define _ARCXCNN_H
+
+enum arcxcnn_chip_id {
+	ARC2C0608
+};
+
+enum arcxcnn_brightness_source {
+	ARCXCNN_PWM_ONLY,
+	ARCXCNN_I2C_ONLY = 2,
+};
+
+#define ARCXCNN_MAX_PROGENTRIES	48	/* max a/v pairs for custom */
+
+/**
+ * struct arcxcnn_platform_data
+ * @name : Backlight driver name. If it is not defined, default name is set.
+ * @initial_brightness : initial value of backlight brightness
+ * @period_ns : platform specific pwm period value. unit is nano.
+		Only valid when mode is PWM_BASED.
+ * @led_str : initial LED string
+ */
+struct arcxcnn_platform_data {
+	const char *name;
+	u16 initial_brightness;
+	unsigned int period_ns;
+	u8     ledstr;
+	u8     prog_addr[ARCXCNN_MAX_PROGENTRIES];
+	u8     prog_data[ARCXCNN_MAX_PROGENTRIES];
+	u32    prog_entries;
+};
+
+#endif
-- 
2.7.4