[PATCH 1/1] BACKLIGHT: Add Driver for ARCXCNN Chip

[Olimpiu Dejeu <olimpiu@arcticsand.com>]

This is the driver for the Arctic Sand Technologies Inc. ARCXCNN LED
backlight IC family.

Signed-off-by: Olimpiu Dejeu <olimpiu@arcticsand.com>
---
 drivers/video/backlight/Kconfig      |   7 +
 drivers/video/backlight/Makefile     |   1 +
 drivers/video/backlight/arcxcnn_bl.c | 499 +++++++++++++++++++++++++++++++++++
 include/linux/i2c/arcxcnn.h          |  41 +++
 4 files changed, 547 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 5a3eb2e..19ee87d 100644
--- a/drivers/video/backlight/Kconfig
+++ b/drivers/video/backlight/Kconfig
@@ -444,6 +444,13 @@ 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 bb82002..9d7f3ec 100644
--- a/drivers/video/backlight/Makefile
+++ b/drivers/video/backlight/Makefile
@@ -53,3 +53,4 @@ obj-$(CONFIG_BACKLIGHT_SAHARA)		+= kb3886_bl.o
 obj-$(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..40a6c48
--- /dev/null
+++ b/drivers/video/backlight/arcxcnn_bl.c
@@ -0,0 +1,499 @@
+/*
+ * 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)	/* <reserved> 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 = 0;
+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;
+
+	if (!node) {
+		dev_err(dev, "no platform data\n");
+		return -EINVAL;
+	}
+
+	of_property_read_string(node, "bl-name", &lp->pdata->name);
+	of_property_read_u16(node, "init-brt", &lp->pdata->initial_brightness);
+	of_property_read_u32(node, "pwm-period", &lp->pdata->period_ns);
+
+	if (lp->pdata->initial_brightness > MAX_BRIGHTNESS)
+		lp->pdata->initial_brightness = MAX_BRIGHTNESS;
+
+	/* 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_u8(child, "prg-addr", &lp->pdata->prog_addr[i]);
+			of_property_read_u8(child, "prg-data", &lp->pdata->prog_data[i]);
+			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(struct arcxcnn), 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,arcxcnn", },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, arcxcnn_dt_ids);
+
+static const struct i2c_device_id arcxcnn_ids[] = {
+	{"arcxcnn", ARCXCNN},
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, arcxcnn_ids);
+
+static struct i2c_driver arcxcnn_driver = {
+	.driver = {
+		   .name = "arcxcnn",
+		   .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..67e8214
--- /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 {
+	ARCXCNN,
+};
+
+enum arcxcnn_brighntess_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