Re: [PATCH v8 04/11] backlight: add support for tps6116x controller

[Kevin Hilman <khilman@ti.com>]

Richard,

Cyril Chemparathy <cyril@ti.com> writes:

> TPS6116x is an EasyScale backlight controller device.  This driver supports
> TPS6116x devices connected on a single GPIO.
>
> Signed-off-by: Cyril Chemparathy <cyril@ti.com>

Any comments on this driver?

With your Ack, I'll be happy to merge it via the davinci tree with the
rest of the series.

Thanks,

Kevin

> ---
>  drivers/video/backlight/Kconfig    |    7 +
>  drivers/video/backlight/Makefile   |    2 +-
>  drivers/video/backlight/tps6116x.c |  299 ++++++++++++++++++++++++++++++++++++
>  3 files changed, 307 insertions(+), 1 deletions(-)
>  create mode 100644 drivers/video/backlight/tps6116x.c
>
> diff --git a/drivers/video/backlight/Kconfig b/drivers/video/backlight/Kconfig
> index e54a337..06e868e 100644
> --- a/drivers/video/backlight/Kconfig
> +++ b/drivers/video/backlight/Kconfig
> @@ -307,6 +307,13 @@ config BACKLIGHT_PCF50633
>  	  If you have a backlight driven by a NXP PCF50633 MFD, say Y here to
>  	  enable its driver.
>  
> +config BACKLIGHT_TPS6116X
> +	tristate "TPS6116X LCD Backlight"
> +	depends on GENERIC_GPIO
> +	help
> +	  This driver controls the LCD backlight level for EasyScale capable
> +	  SSP connected backlight controllers.
> +
>  endif # BACKLIGHT_CLASS_DEVICE
>  
>  endif # BACKLIGHT_LCD_SUPPORT
> diff --git a/drivers/video/backlight/Makefile b/drivers/video/backlight/Makefile
> index 44c0f81..5d407c8 100644
> --- a/drivers/video/backlight/Makefile
> +++ b/drivers/video/backlight/Makefile
> @@ -35,4 +35,4 @@ obj-$(CONFIG_BACKLIGHT_ADP5520)	+= adp5520_bl.o
>  obj-$(CONFIG_BACKLIGHT_ADP8860)	+= adp8860_bl.o
>  obj-$(CONFIG_BACKLIGHT_88PM860X) += 88pm860x_bl.o
>  obj-$(CONFIG_BACKLIGHT_PCF50633)	+= pcf50633-backlight.o
> -
> +obj-$(CONFIG_BACKLIGHT_TPS6116X)+= tps6116x.o
> diff --git a/drivers/video/backlight/tps6116x.c b/drivers/video/backlight/tps6116x.c
> new file mode 100644
> index 0000000..7f846ab
> --- /dev/null
> +++ b/drivers/video/backlight/tps6116x.c
> @@ -0,0 +1,299 @@
> +/*
> + * TPS6116X LCD Backlight Controller Driver
> + *
> + * Copyright (C) 2010 Texas Instruments
> + *
> + * This program is free software; you can redistribute it and/or
> + * modify it under the terms of the GNU General Public License as
> + * published by the Free Software Foundation version 2.
> + *
> + * This program is distributed "as is" WITHOUT ANY WARRANTY of any kind,
> + * whether express or implied; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> + * General Public License for more details.
> + */
> +
> +#include <linux/kernel.h>
> +#include <linux/fb.h>
> +#include <linux/err.h>
> +#include <linux/delay.h>
> +#include <linux/gpio.h>
> +#include <linux/backlight.h>
> +#include <linux/platform_device.h>
> +#include <linux/regulator/consumer.h>
> +
> +#define TPS6116X_MAX_INTENSITY		31
> +#define TPS6116X_DEFAULT_INTENSITY	10
> +
> +/* Easyscale timing w/ margin (usecs) */
> +#define T_POWER_SETTLE			2000
> +#define T_ES_DELAY			120
> +#define T_ES_DETECT			280
> +#define T_ES_WINDOW			(1000 - T_ES_DELAY - T_ES_DETECT)
> +#define T_START				3
> +#define T_EOS				3
> +#define T_INACTIVE			3
> +#define T_ACTIVE			(3 * T_INACTIVE)
> +
> +#define CMD_SET				0x72
> +
> +struct tps6116x {
> +	struct ti_ssp_device		*handle;
> +	struct device			*dev;
> +	int				gpio;
> +	struct mutex			lock;
> +	int				intensity;
> +	struct backlight_properties	props;
> +	struct backlight_device		*bl;
> +	struct regulator		*regulator;
> +	bool				power;
> +	bool				suspended;
> +};
> +
> +static int __set_power(struct tps6116x *hw, bool power)
> +{
> +	unsigned long flags;
> +	int error;
> +
> +	if (power == hw->power)
> +		return 0; /* nothing to do */
> +
> +	/* disabling is simple... choke power */
> +	if (!power) {
> +		error = regulator_disable(hw->regulator);
> +		goto done;
> +	}
> +
> +	/* set ctrl pin init state for easyscale detection */
> +	gpio_set_value(hw->gpio, 0);
> +
> +	error = regulator_enable(hw->regulator);
> +	if (error < 0)
> +		goto done;
> +
> +	udelay(T_POWER_SETTLE);
> +
> +	/*
> +	 * Now that the controller is powered up, we need to put it into 1-wire
> +	 * mode.  This is a timing sensitive operation, hence the irq disable.
> +	 * Ideally, this should happen rarely, and mostly at init, so disabling
> +	 * interrupts for the duration should not be a problem.
> +	 */
> +	local_irq_save(flags);
> +
> +	gpio_set_value(hw->gpio, 1);
> +	udelay(T_ES_DELAY);
> +	gpio_set_value(hw->gpio, 0);
> +	udelay(T_ES_DETECT);
> +	gpio_set_value(hw->gpio, 1);
> +
> +	local_irq_restore(flags);
> +
> +done:
> +	if (error >= 0)
> +		hw->power = power;
> +
> +	return error;
> +}
> +
> +static void __write_byte(struct tps6116x *hw, u8 data)
> +{
> +	int bit;
> +
> +	gpio_set_value(hw->gpio, 1);
> +	udelay(T_START);
> +
> +	for (bit = 0; bit < 8; bit++, data <<= 1) {
> +		int val = data & 0x80;
> +		int t_lo = val ? T_INACTIVE : T_ACTIVE;
> +		int t_hi = val ? T_ACTIVE : T_INACTIVE;
> +
> +		gpio_set_value(hw->gpio, 0);
> +		udelay(t_lo);
> +		gpio_set_value(hw->gpio, 1);
> +		udelay(t_hi);
> +	}
> +
> +	gpio_set_value(hw->gpio, 0);
> +	udelay(T_EOS);
> +	gpio_set_value(hw->gpio, 1);
> +}
> +
> +static void __set_intensity(struct tps6116x *hw, int intensity)
> +{
> +	unsigned long flags;
> +
> +	intensity = clamp(intensity, 0, TPS6116X_MAX_INTENSITY);
> +
> +	local_irq_save(flags);
> +	__write_byte(hw, CMD_SET);
> +	__write_byte(hw, intensity);
> +	local_irq_restore(flags);
> +}
> +
> +static int set_intensity(struct tps6116x *hw, int intensity)
> +{
> +	int error = 0;
> +
> +	if (intensity == hw->intensity)
> +		return 0;
> +
> +	mutex_lock(&hw->lock);
> +
> +	error = __set_power(hw, intensity ? true : false);
> +	if (error < 0)
> +		goto error;
> +
> +	if (intensity > 0)
> +		__set_intensity(hw, intensity);
> +
> +	hw->intensity = intensity;
> +error:
> +	mutex_unlock(&hw->lock);
> +
> +	return error;
> +}
> +
> +static int get_brightness(struct backlight_device *bl)
> +{
> +	struct tps6116x *hw = bl_get_data(bl);
> +
> +	return hw->intensity;
> +}
> +
> +static int update_status(struct backlight_device *bl)
> +{
> +	struct tps6116x *hw = bl_get_data(bl);
> +	int intensity = bl->props.brightness;
> +
> +	if (hw->suspended || hw->props.state & BL_CORE_SUSPENDED)
> +		intensity = 0;
> +	if (bl->props.power != FB_BLANK_UNBLANK)
> +		intensity = 0;
> +	if (bl->props.fb_blank != FB_BLANK_UNBLANK)
> +		intensity = 0;
> +
> +	return set_intensity(hw, intensity);
> +}
> +
> +static const struct backlight_ops tps6116x_backlight_ops = {
> +	.options	= BL_CORE_SUSPENDRESUME,
> +	.get_brightness	= get_brightness,
> +	.update_status	= update_status,
> +};
> +
> +static int __devinit tps6116x_probe(struct platform_device *pdev)
> +{
> +	struct tps6116x *hw;
> +	struct device *dev = &pdev->dev;
> +	struct backlight_properties props;
> +	int error;
> +
> +	hw = kzalloc(sizeof(struct tps6116x), GFP_KERNEL);
> +	if (!hw) {
> +		dev_err(dev, "cannot allocate driver data\n");
> +		return -ENOMEM;
> +	}
> +	platform_set_drvdata(pdev, hw);
> +
> +	hw->gpio = (int)dev->platform_data;
> +	hw->dev = dev;
> +
> +	mutex_init(&hw->lock);
> +
> +	hw->regulator = regulator_get(dev, "vlcd");
> +	if (IS_ERR(hw->regulator)) {
> +		error = PTR_ERR(hw->regulator);
> +		dev_err(dev, "cannot claim regulator\n");
> +		goto error_regulator;
> +	}
> +
> +	error = gpio_request_one(hw->gpio, GPIOF_DIR_OUT, dev_name(dev));
> +	if (error < 0) {
> +		dev_err(dev, "cannot claim gpio\n");
> +		goto error_gpio;
> +	}
> +
> +	memset(&props, 0, sizeof(props));
> +	props.max_brightness = TPS6116X_MAX_INTENSITY;
> +	props.brightness     = TPS6116X_DEFAULT_INTENSITY;
> +	props.power          = FB_BLANK_UNBLANK;
> +
> +	hw->bl = backlight_device_register("tps6116x", hw->dev, hw,
> +					   &tps6116x_backlight_ops, &props);
> +	if (IS_ERR(hw->bl)) {
> +		error = PTR_ERR(hw->bl);
> +		dev_err(dev, "backlight registration failed\n");
> +		goto error_register;
> +	}
> +
> +	update_status(hw->bl);
> +	dev_info(dev, "registered backlight controller\n");
> +	return 0;
> +
> +error_register:
> +	gpio_free(hw->gpio);
> +error_gpio:
> +	regulator_put(hw->regulator);
> +error_regulator:
> +	kfree(hw);
> +	platform_set_drvdata(pdev, NULL);
> +	return error;
> +}
> +
> +static int __devexit tps6116x_remove(struct platform_device *pdev)
> +{
> +	struct tps6116x *hw = platform_get_drvdata(pdev);
> +
> +	backlight_device_unregister(hw->bl);
> +	regulator_disable(hw->regulator);
> +	regulator_put(hw->regulator);
> +	gpio_free(hw->gpio);
> +	kfree(hw);
> +	platform_set_drvdata(pdev, NULL);
> +	return 0;
> +}
> +
> +static int tps6116x_suspend(struct platform_device *pdev, pm_message_t state)
> +{
> +	struct tps6116x *hw = platform_get_drvdata(pdev);
> +	hw->suspended = true;
> +	update_status(hw->bl);
> +	return 0;
> +}
> +
> +static int tps6116x_resume(struct platform_device *pdev)
> +{
> +	struct tps6116x *hw = platform_get_drvdata(pdev);
> +	hw->suspended = false;
> +	update_status(hw->bl);
> +	return 0;
> +}
> +
> +static struct platform_driver tps6116x_driver = {
> +	.probe		= tps6116x_probe,
> +	.remove		= __devexit_p(tps6116x_remove),
> +	.suspend	= tps6116x_suspend,
> +	.resume		= tps6116x_resume,
> +	.driver		= {
> +		.name	= "tps6116x",
> +		.owner	= THIS_MODULE,
> +	},
> +};
> +
> +static int __init tps6116x_init(void)
> +{
> +	return platform_driver_register(&tps6116x_driver);
> +}
> +module_init(tps6116x_init);
> +
> +static void __exit tps6116x_exit(void)
> +{
> +	platform_driver_unregister(&tps6116x_driver);
> +}
> +module_exit(tps6116x_exit);
> +
> +MODULE_DESCRIPTION("SSP TPS6116X Driver");
> +MODULE_AUTHOR("Cyril Chemparathy");
> +MODULE_LICENSE("GPL");
> +MODULE_ALIAS("platform:tps6116x");