Message-ID: <20141203024230.GA3333@jack-ThinkPad-T520>
Date:	Wed, 3 Dec 2014 11:42:31 +0900
From:	Gyungoh Yoo <gyungoh@...il.com>
To:	Jingoo Han <jg1.han@...sung.com>
Cc:	sameo@...ux.intel.com, lee.jones@...aro.org, cooloney@...il.com,
	broonie@...nel.org, lgirdwood@...il.com, jack.yoo@...worksinc.com,
	linux-kernel@...r.kernel.org, devicetree@...r.kernel.org,
	grant.likely@...aro.org, robh+dt@...nel.org, mark.rutland@....com,
	ijc+devicetree@...lion.org.uk, galak@...eaurora.org,
	pawel.moll@....com, heiko@...ech.de, jason@...edaemon.net,
	treding@...dia.com, florian.vaussard@...l.ch, trivial@...nel.org,
	linux@...ck-us.net, andrew@...n.ch, jic23@...nel.org
Subject: Re: [PATCH v9 2/8] backlight: Add support Skyworks SKY81452
 backlight driver

On Wed, Dec 03, 2014 at 11:19:06AM +0900, Jingoo Han wrote:
> On Tuesday, December 02, 2014 5:05 PM, Gyungoh Yoo wrote:
> > 
> > From: Gyungoh Yoo <jack.yoo@...worksinc.com>
> > 
> > Signed-off-by: Gyungoh Yoo <jack.yoo@...worksinc.com>
> > ---
> > Changes v9:
> > Nothing
> > 
> > Changes v8:
> > Renamed property names for backlight with vendor prefix
> > Modified gpio-enable property to generic property for GPIO
> > 
> > Changes v7:
> > Modified licensing text to GPLv2
> > 
> > Changes v6:
> > Added new line character at the end of line of dev_err()
> > 
> > Changes v5:
> > Move sky81452-backlight.h to include/linux/platform_data
> > 
> > Changes v4:
> > Reordering header files for readability
> > Removed calling to backlight_device_unregister()
> > Removed MODULE_VERSION()
> > Modified license to GPLv2
> > 
> > Changes v3:
> > Modified DBG messages
> > 
> > Changes v2:
> > Added 'compatible' attribute in the driver
> > Added message for exception or errors
> > 
> >  drivers/video/backlight/Kconfig                  |  10 +
> >  drivers/video/backlight/Makefile                 |   1 +
> >  drivers/video/backlight/sky81452-backlight.c     | 340 +++++++++++++++++++++++
> >  include/linux/platform_data/sky81452-backlight.h |  46 +++
> >  4 files changed, 397 insertions(+)
> >  create mode 100644 drivers/video/backlight/sky81452-backlight.c
> >  create mode 100644 include/linux/platform_data/sky81452-backlight.h
> > 
> > diff --git a/drivers/video/backlight/Kconfig b/drivers/video/backlight/Kconfig
> > index 8d03924..2586fdd 100644
> > --- a/drivers/video/backlight/Kconfig
> > +++ b/drivers/video/backlight/Kconfig
> > @@ -409,6 +409,16 @@ config BACKLIGHT_PANDORA
> >  	  If you have a Pandora console, say Y to enable the
> >  	  backlight driver.
> > 
> > +config BACKLIGHT_SKY81452
> > +	tristate "Backlight driver for SKY81452"
> > +	depends on BACKLIGHT_CLASS_DEVICE && MFD_SKY81452
> > +	help
> > +	  If you have a Skyworks SKY81452, say Y to enable the
> > +	  backlight driver.
> > +
> > +	  To compile this driver as a module, choose M here: the module will
> > +	  be called sky81452-backlight
> > +
> >  config BACKLIGHT_TPS65217
> >  	tristate "TPS65217 Backlight"
> >  	depends on BACKLIGHT_CLASS_DEVICE && MFD_TPS65217
> > diff --git a/drivers/video/backlight/Makefile b/drivers/video/backlight/Makefile
> > index fcd50b73..d67073f 100644
> > --- a/drivers/video/backlight/Makefile
> > +++ b/drivers/video/backlight/Makefile
> > @@ -50,6 +50,7 @@ obj-$(CONFIG_BACKLIGHT_PANDORA)		+= pandora_bl.o
> >  obj-$(CONFIG_BACKLIGHT_PCF50633)	+= pcf50633-backlight.o
> >  obj-$(CONFIG_BACKLIGHT_PWM)		+= pwm_bl.o
> >  obj-$(CONFIG_BACKLIGHT_SAHARA)		+= kb3886_bl.o
> > +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
> > diff --git a/drivers/video/backlight/sky81452-backlight.c b/drivers/video/backlight/sky81452-
> > backlight.c
> > new file mode 100644
> > index 0000000..45e575f
> > --- /dev/null
> > +++ b/drivers/video/backlight/sky81452-backlight.c
> > @@ -0,0 +1,340 @@
> > +/*
> > + * sky81452-backlight.c	SKY81452 backlight driver
> > + *
> > + * Copyright 2014 Skyworks Solutions Inc.
> > + * Author : Gyungoh Yoo <jack.yoo@...worksinc.com>
> > + *
> > + * This program is free software; you can redistribute it and/or modify it
> > + * under the terms of the GNU General Public License version 2
> > + * as published by the Free Software Foundation.
> > + *
> > + * This program is distributed in the hope that it will be useful, but
> > + * WITHOUT ANY WARRANTY; without even the implied warranty of
> > + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> > + * General Public License for more details.
> > + *
> > + * You should have received a copy of the GNU General Public License along
> > + * with this program; if not, see <http://www.gnu.org/licenses/>.
> > + */
> > +
> > +#include <linux/backlight.h>
> > +#include <linux/err.h>
> > +#include <linux/gpio.h>
> > +#include <linux/init.h>
> > +#include <linux/kernel.h>
> > +#include <linux/module.h>
> > +#include <linux/of.h>
> > +#include <linux/of_gpio.h>
> > +#include <linux/platform_device.h>
> > +#include <linux/regmap.h>
> > +#include <linux/platform_data/sky81452-backlight.h>
> > +#include <linux/slab.h>
> > +
> > +/* registers */
> > +#define SKY81452_REG0	0x00
> > +#define SKY81452_REG1	0x01
> > +#define SKY81452_REG2	0x02
> > +#define SKY81452_REG4	0x04
> > +#define SKY81452_REG5	0x05
> > +
> > +/* bit mask */
> > +#define SKY81452_CS	0xFF
> > +#define SKY81452_EN	0x3F
> > +#define SKY81452_IGPW	0x20
> > +#define SKY81452_PWMMD	0x10
> > +#define SKY81452_PHASE	0x08
> > +#define SKY81452_ILIM	0x04
> > +#define SKY81452_VSHRT	0x03
> > +#define SKY81452_OCP	0x80
> > +#define SKY81452_OTMP	0x40
> > +#define SKY81452_SHRT	0x3F
> > +#define SKY81452_OPN	0x3F
> > +
> > +#define SKY81452_DEFAULT_NAME "lcd-backlight"
> > +#define SKY81452_MAX_BRIGHTNESS	(SKY81452_CS + 1)
> > +
> > +#define CTZ(b) __builtin_ctz(b)
> > +
> > +static int sky81452_bl_update_status(struct backlight_device *bd)
> > +{
> > +	const struct sky81452_bl_platform_data *pdata =
> > +			dev_get_platdata(bd->dev.parent);
> > +	const unsigned int brightness = (unsigned int)bd->props.brightness;
> > +	struct regmap *regmap = bl_get_data(bd);
> > +	int ret;
> > +
> > +	if (brightness > 0) {
> > +		ret = regmap_write(regmap, SKY81452_REG0, brightness - 1);
> > +		if (IS_ERR_VALUE(ret))
> > +			return ret;
> > +
> > +		return regmap_update_bits(regmap, SKY81452_REG1, SKY81452_EN,
> > +					pdata->enable << CTZ(SKY81452_EN));
> > +	}
> > +
> > +	return regmap_update_bits(regmap, SKY81452_REG1, SKY81452_EN, 0);
> > +}
> > +
> > +static int sky81452_bl_get_brightness(struct backlight_device *bd)
> > +{
> > +	return bd->props.brightness;
> > +}
> 
> Please remove sky81452_bl_get_brightness().
> In the case of just returning 'props.brightness',
> backglight core can also return 'props.brightness'.
> So, there is no need to add sky81452_bl_get_brightness().
> 
> Please refer to the following patches.
>   backlight: Remove trivial get_brightness implementations
>   backlight: Show brightness even if get_brightness is not implemented

I see. I will remove it.
Thank you.

> 
> Others look good.
> Thanks.
> 
> Best regards,
> Jingoo Han
> 
> > +
> > +static const struct backlight_ops sky81452_bl_ops = {
> > +	.update_status = sky81452_bl_update_status,
> > +	.get_brightness = sky81452_bl_get_brightness,
> > +};
> > +
> > +static ssize_t sky81452_bl_store_enable(struct device *dev,
> > +		struct device_attribute *attr, const char *buf, size_t count)
> > +{
> > +	struct regmap *regmap = bl_get_data(to_backlight_device(dev));
> > +	unsigned long value;
> > +	int ret;
> > +
> > +	ret = kstrtoul(buf, 16, &value);
> > +	if (IS_ERR_VALUE(ret))
> > +		return ret;
> > +
> > +	ret = regmap_update_bits(regmap, SKY81452_REG1, SKY81452_EN,
> > +					value << CTZ(SKY81452_EN));
> > +	if (IS_ERR_VALUE(ret))
> > +		return ret;
> > +
> > +	return count;
> > +}
> > +
> > +static ssize_t sky81452_bl_show_open_short(struct device *dev,
> > +		struct device_attribute *attr, char *buf)
> > +{
> > +	struct regmap *regmap = bl_get_data(to_backlight_device(dev));
> > +	unsigned int reg, value = 0;
> > +	char tmp[3];
> > +	int i, ret;
> > +
> > +	reg = !strcmp(attr->attr.name, "open") ? SKY81452_REG5 : SKY81452_REG4;
> > +	ret = regmap_read(regmap, reg, &value);
> > +	if (IS_ERR_VALUE(ret))
> > +		return ret;
> > +
> > +	if (value & SKY81452_SHRT) {
> > +		*buf = 0;
> > +		for (i = 0; i < 6; i++) {
> > +			if (value & 0x01) {
> > +				sprintf(tmp, "%d ", i + 1);
> > +				strcat(buf, tmp);
> > +			}
> > +			value >>= 1;
> > +		}
> > +		strcat(buf, "\n");
> > +	} else {
> > +		strcpy(buf, "none\n");
> > +	}
> > +
> > +	return strlen(buf);
> > +}
> > +
> > +static ssize_t sky81452_bl_show_fault(struct device *dev,
> > +		struct device_attribute *attr, char *buf)
> > +{
> > +	struct regmap *regmap = bl_get_data(to_backlight_device(dev));
> > +	unsigned int value = 0;
> > +	int ret;
> > +
> > +	ret = regmap_read(regmap, SKY81452_REG4, &value);
> > +	if (IS_ERR_VALUE(ret))
> > +		return ret;
> > +
> > +	*buf = 0;
> > +
> > +	if (value & SKY81452_OCP)
> > +		strcat(buf, "over-current ");
> > +
> > +	if (value & SKY81452_OTMP)
> > +		strcat(buf, "over-temperature");
> > +
> > +	strcat(buf, "\n");
> > +	return strlen(buf);
> > +}
> > +
> > +static DEVICE_ATTR(enable, S_IWGRP | S_IWUSR, NULL, sky81452_bl_store_enable);
> > +static DEVICE_ATTR(open, S_IRUGO, sky81452_bl_show_open_short, NULL);
> > +static DEVICE_ATTR(short, S_IRUGO, sky81452_bl_show_open_short, NULL);
> > +static DEVICE_ATTR(fault, S_IRUGO, sky81452_bl_show_fault, NULL);
> > +
> > +static struct attribute *sky81452_bl_attribute[] = {
> > +	&dev_attr_enable.attr,
> > +	&dev_attr_open.attr,
> > +	&dev_attr_short.attr,
> > +	&dev_attr_fault.attr,
> > +	NULL
> > +};
> > +
> > +static const struct attribute_group sky81452_bl_attr_group = {
> > +	.attrs = sky81452_bl_attribute,
> > +};
> > +
> > +#ifdef CONFIG_OF
> > +static struct sky81452_bl_platform_data *sky81452_bl_parse_dt(
> > +							struct device *dev)
> > +{
> > +	struct device_node *np = of_node_get(dev->of_node);
> > +	struct sky81452_bl_platform_data *pdata;
> > +	int ret;
> > +
> > +	if (!np) {
> > +		dev_err(dev, "backlight node not found.\n");
> > +		return ERR_PTR(-ENODATA);
> > +	}
> > +
> > +	pdata = devm_kzalloc(dev, sizeof(*pdata), GFP_KERNEL);
> > +	if (!pdata) {
> > +		of_node_put(np);
> > +		return ERR_PTR(-ENOMEM);
> > +	}
> > +
> > +	of_property_read_string(np, "name", &pdata->name);
> > +	pdata->ignore_pwm = of_property_read_bool(np, "skyworks,ignore-pwm");
> > +	pdata->dpwm_mode = of_property_read_bool(np, "skyworks,dpwm-mode");
> > +	pdata->phase_shift = of_property_read_bool(np, "skyworks,phase-shift");
> > +	pdata->gpio_enable = of_get_gpio(np, 0);
> > +
> > +	ret = of_property_read_u32(np, "skyworks,en-channels", &pdata->enable);
> > +	if (IS_ERR_VALUE(ret))
> > +		pdata->enable = SKY81452_EN >> CTZ(SKY81452_EN);
> > +
> > +	ret = of_property_read_u32(np, "skyworks,short-detection-threshold",
> > +			&pdata->short_detection_threshold);
> > +	if (IS_ERR_VALUE(ret))
> > +		pdata->short_detection_threshold = 7;
> > +
> > +	ret = of_property_read_u32(np, "skyworks,current-limit",
> > +			&pdata->boost_current_limit);
> > +	if (IS_ERR_VALUE(ret))
> > +		pdata->boost_current_limit = 2750;
> > +
> > +	of_node_put(np);
> > +	return pdata;
> > +}
> > +#else
> > +static struct sky81452_bl_platform_data *sky81452_bl_parse_dt(
> > +							struct device *dev)
> > +{
> > +	return ERR_PTR(-EINVAL);
> > +}
> > +#endif
> > +
> > +static int sky81452_bl_init_device(struct regmap *regmap,
> > +		struct sky81452_bl_platform_data *pdata)
> > +{
> > +	unsigned int value;
> > +
> > +	value = pdata->ignore_pwm ? SKY81452_IGPW : 0;
> > +	value |= pdata->dpwm_mode ? SKY81452_PWMMD : 0;
> > +	value |= pdata->phase_shift ? 0 : SKY81452_PHASE;
> > +
> > +	if (pdata->boost_current_limit == 2300)
> > +		value |= SKY81452_ILIM;
> > +	else if (pdata->boost_current_limit != 2750)
> > +		return -EINVAL;
> > +
> > +	if (pdata->short_detection_threshold < 4 ||
> > +				pdata->short_detection_threshold > 7)
> > +		return -EINVAL;
> > +	value |= (7 - pdata->short_detection_threshold) << CTZ(SKY81452_VSHRT);
> > +
> > +	return regmap_write(regmap, SKY81452_REG2, value);
> > +}
> > +
> > +static int sky81452_bl_probe(struct platform_device *pdev)
> > +{
> > +	struct device *dev = &pdev->dev;
> > +	struct regmap *regmap = dev_get_drvdata(dev->parent);
> > +	struct sky81452_bl_platform_data *pdata = dev_get_platdata(dev);
> > +	struct backlight_device *bd;
> > +	struct backlight_properties props;
> > +	const char *name;
> > +	int ret;
> > +
> > +	if (!pdata) {
> > +		pdata = sky81452_bl_parse_dt(dev);
> > +		if (IS_ERR(pdata))
> > +			return PTR_ERR(pdata);
> > +	}
> > +
> > +	if (gpio_is_valid(pdata->gpio_enable)) {
> > +		ret = devm_gpio_request_one(dev, pdata->gpio_enable,
> > +					GPIOF_OUT_INIT_HIGH, "sky81452-en");
> > +		if (IS_ERR_VALUE(ret)) {
> > +			dev_err(dev, "failed to request GPIO. err=%d\n", ret);
> > +			return ret;
> > +		}
> > +	}
> > +
> > +	ret = sky81452_bl_init_device(regmap, pdata);
> > +	if (IS_ERR_VALUE(ret)) {
> > +		dev_err(dev, "failed to initialize. err=%d\n", ret);
> > +		return ret;
> > +	}
> > +
> > +	memset(&props, 0, sizeof(props));
> > +	props.max_brightness = SKY81452_MAX_BRIGHTNESS,
> > +	name = pdata->name ? pdata->name : SKY81452_DEFAULT_NAME;
> > +	bd = devm_backlight_device_register(dev, name, dev, regmap,
> > +						&sky81452_bl_ops, &props);
> > +	if (IS_ERR(bd)) {
> > +		dev_err(dev, "failed to register. err=%ld\n", PTR_ERR(bd));
> > +		return PTR_ERR(bd);
> > +	}
> > +
> > +	platform_set_drvdata(pdev, bd);
> > +
> > +	ret  = sysfs_create_group(&bd->dev.kobj, &sky81452_bl_attr_group);
> > +	if (IS_ERR_VALUE(ret)) {
> > +		dev_err(dev, "failed to create attribute. err=%d\n", ret);
> > +		return ret;
> > +	}
> > +
> > +	return ret;
> > +}
> > +
> > +static int sky81452_bl_remove(struct platform_device *pdev)
> > +{
> > +	const struct sky81452_bl_platform_data *pdata =
> > +						dev_get_platdata(&pdev->dev);
> > +	struct backlight_device *bd = platform_get_drvdata(pdev);
> > +
> > +	sysfs_remove_group(&bd->dev.kobj, &sky81452_bl_attr_group);
> > +
> > +	bd->props.power = FB_BLANK_UNBLANK;
> > +	bd->props.brightness = 0;
> > +	backlight_update_status(bd);
> > +
> > +	if (gpio_is_valid(pdata->gpio_enable))
> > +		gpio_set_value_cansleep(pdata->gpio_enable, 0);
> > +
> > +	return 0;
> > +}
> > +
> > +#ifdef CONFIG_OF
> > +static const struct of_device_id sky81452_bl_of_match[] = {
> > +	{ .compatible = "skyworks,sky81452-backlight", },
> > +	{ }
> > +};
> > +MODULE_DEVICE_TABLE(of, sky81452_bl_of_match);
> > +#endif
> > +
> > +static struct platform_driver sky81452_bl_driver = {
> > +	.driver = {
> > +		.name = "sky81452-backlight",
> > +		.of_match_table = of_match_ptr(sky81452_bl_of_match),
> > +	},
> > +	.probe = sky81452_bl_probe,
> > +	.remove = sky81452_bl_remove,
> > +};
> > +
> > +module_platform_driver(sky81452_bl_driver);
> > +
> > +MODULE_DESCRIPTION("Skyworks SKY81452 backlight driver");
> > +MODULE_AUTHOR("Gyungoh Yoo <jack.yoo@...worksinc.com>");
> > +MODULE_LICENSE("GPL v2");
> > diff --git a/include/linux/platform_data/sky81452-backlight.h b/include/linux/platform_data/sky81452-
> > backlight.h
> > new file mode 100644
> > index 0000000..1231e9b
> > --- /dev/null
> > +++ b/include/linux/platform_data/sky81452-backlight.h
> > @@ -0,0 +1,46 @@
> > +/*
> > + * sky81452.h	SKY81452 backlight driver
> > + *
> > + * Copyright 2014 Skyworks Solutions Inc.
> > + * Author : Gyungoh Yoo <jack.yoo@...worksinc.com>
> > + *
> > + * This program is free software; you can redistribute it and/or modify it
> > + * under the terms of the GNU General Public License version 2
> > + * as published by the Free Software Foundation.
> > + *
> > + * This program is distributed in the hope that it will be useful, but
> > + * WITHOUT ANY WARRANTY; without even the implied warranty of
> > + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> > + * General Public License for more details.
> > + *
> > + * You should have received a copy of the GNU General Public License along
> > + * with this program; if not, see <http://www.gnu.org/licenses/>.
> > + */
> > +
> > +#ifndef _SKY81452_BACKLIGHT_H
> > +#define _SKY81452_BACKLIGHT_H
> > +
> > +/**
> > + * struct sky81452_platform_data
> > + * @name:	backlight driver name.
> > +		If it is not defined, default name is lcd-backlight.
> > + * @gpio_enable:GPIO number which control EN pin
> > + * @enable:	Enable mask for current sink channel 1, 2, 3, 4, 5 and 6.
> > + * @ignore_pwm:	true if DPWMI should be ignored.
> > + * @dpwm_mode:	true is DPWM dimming mode, otherwise Analog dimming mode.
> > + * @phase_shift:true is phase shift mode.
> > + * @short_detecion_threshold:	It should be one of 4, 5, 6 and 7V.
> > + * @boost_current_limit:	It should be one of 2300, 2750mA.
> > + */
> > +struct sky81452_bl_platform_data {
> > +	const char *name;
> > +	int gpio_enable;
> > +	unsigned int enable;
> > +	bool ignore_pwm;
> > +	bool dpwm_mode;
> > +	bool phase_shift;
> > +	unsigned int short_detection_threshold;
> > +	unsigned int boost_current_limit;
> > +};
> > +
> > +#endif
> > --
> > 1.9.1
> 
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