Date:   Thu, 10 Nov 2016 08:14:47 +0000
From:   Lee Jones <lee.jones@...aro.org>
To:     Olimpiu Dejeu <olimpiu@...ticsand.com>
Cc:     robh@...nel.org, linux-kernel@...r.kernel.org,
        linux-fbdev@...r.kernel.org, devicetree@...r.kernel.org,
        jingoohan1@...il.com
Subject: Re: [PATCH 1/2] backlight: arcxcnn: add support for ArticSand devices

On Wed, 09 Nov 2016, Lee Jones wrote:

> Jingoo?

Ah, it looks like you used the wrong address.

I should have been: jingoohan1@...il.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@...ticsand.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@...look.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
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