Re: [PATCH v2] leds: add new lp8788 led driver

[Shuah Khan <shuahkhan@gmail.com>]

On Fri, 2012-07-20 at 08:43 +0000, Kim, Milo wrote:
> TI LP8788 PMU has the current sink as the keyboard led driver.
> The brightness is controlled by the i2c commands.
> Configurable parameters can be defined in the platform side.
> 
> Patch v2.
> (a) use workqueue on changing the brightness
> 
> (b) use mutex_lock/unlock when the brightness is set
>     and the led block of lp8788 device is enabled
> 
> (c) remove err_dev on _probe()
>     : just return as returned value if any errors
> 
> (d) replace module_init/exit() with module_platform_driver()
> 
> (e) add led configuration structure and loading them by default
>     if platform data is null
> 
> Signed-off-by: Milo(Woogyom) Kim <milo.kim@ti.com>
> ---
>  drivers/leds/Kconfig       |    7 ++
>  drivers/leds/Makefile      |    1 +
>  drivers/leds/leds-lp8788.c |  192 ++++++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 200 insertions(+), 0 deletions(-)
>  create mode 100644 drivers/leds/leds-lp8788.c
> 
> diff --git a/drivers/leds/Kconfig b/drivers/leds/Kconfig
> index f028f03..a498deb 100644
> --- a/drivers/leds/Kconfig
> +++ b/drivers/leds/Kconfig
> @@ -200,6 +200,13 @@ config LEDS_LP5523
>  	  Driver provides direct control via LED class and interface for
>  	  programming the engines.
>  
> +config LEDS_LP8788
> +	tristate "LED support for the TI LP8788 PMIC"
> +	depends on LEDS_CLASS
> +	depends on MFD_LP8788
> +	help
> +	  This option enables support for the Keyboard LEDs on the LP8788 PMIC.
> +
>  config LEDS_CLEVO_MAIL
>  	tristate "Mail LED on Clevo notebook"
>  	depends on LEDS_CLASS
> diff --git a/drivers/leds/Makefile b/drivers/leds/Makefile
> index 5eebd7b..f156193 100644
> --- a/drivers/leds/Makefile
> +++ b/drivers/leds/Makefile
> @@ -24,6 +24,7 @@ obj-$(CONFIG_LEDS_GPIO)			+= leds-gpio.o
>  obj-$(CONFIG_LEDS_LP3944)		+= leds-lp3944.o
>  obj-$(CONFIG_LEDS_LP5521)		+= leds-lp5521.o
>  obj-$(CONFIG_LEDS_LP5523)		+= leds-lp5523.o
> +obj-$(CONFIG_LEDS_LP8788)		+= leds-lp8788.o
>  obj-$(CONFIG_LEDS_TCA6507)		+= leds-tca6507.o
>  obj-$(CONFIG_LEDS_CLEVO_MAIL)		+= leds-clevo-mail.o
>  obj-$(CONFIG_LEDS_HP6XX)		+= leds-hp6xx.o
> diff --git a/drivers/leds/leds-lp8788.c b/drivers/leds/leds-lp8788.c
> new file mode 100644
> index 0000000..574b49f
> --- /dev/null
> +++ b/drivers/leds/leds-lp8788.c
> @@ -0,0 +1,192 @@
> +/*
> + * TI LP8788 MFD - keyled driver
> + *
> + * Copyright 2012 Texas Instruments
> + *
> + * Author: Milo(Woogyom) Kim <milo.kim@ti.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.
> + *
> + */
> +
> +#include <linux/module.h>
> +#include <linux/slab.h>
> +#include <linux/err.h>
> +#include <linux/platform_device.h>
> +#include <linux/leds.h>
> +#include <linux/mutex.h>
> +#include <linux/mfd/lp8788.h>
> +#include <linux/mfd/lp8788-isink.h>
> +
> +#define MAX_BRIGHTNESS			LP8788_ISINK_MAX_PWM
> +#define DEFAULT_LED_NAME		"keyboard-backlight"
> +
> +struct lp8788_led {
> +	struct lp8788 *lp;
> +	struct mutex lock;
> +	struct work_struct work;
> +	struct led_classdev led_dev;
> +	enum lp8788_isink_number isink_num;
> +	enum led_brightness brightness;
> +	int on;
> +};
> +
> +struct lp8788_led_config {
> +	enum lp8788_isink_scale scale;
> +	enum lp8788_isink_number num;
> +	int iout;
> +};
> +
> +static struct lp8788_led_config default_led_config = {
> +	.scale = LP8788_ISINK_SCALE_100mA,
> +	.num   = LP8788_ISINK_3,
> +	.iout  = 0,
> +};
> +
> +static int lp8788_led_init_device(struct lp8788_led *led,
> +				struct lp8788_led_platform_data *pdata)
> +{
> +	struct lp8788_led_config *cfg = &default_led_config;
> +	u8 addr, mask, val;
> +	int ret;
> +
> +	if (pdata) {
> +		cfg->scale = pdata->scale;
> +		cfg->num = pdata->num;
> +		cfg->iout = pdata->iout_code;
> +	}
> +
> +	led->isink_num = cfg->num;
> +
> +	/* scale configuration */
> +	addr = LP8788_ISINK_CTRL;
> +	mask = 1 << (cfg->num + LP8788_ISINK_SCALE_OFFSET);
> +	val = cfg->scale << cfg->num;
> +	ret = lp8788_update_bits(led->lp, addr, mask, val);
> +	if (ret)
> +		return ret;
> +
> +	/* current configuration */
> +	addr = lp8788_iout_addr[cfg->num];
> +	mask = lp8788_iout_mask[cfg->num];
> +	val = cfg->iout;
> +
> +	return lp8788_update_bits(led->lp, addr, mask, val);
> +}
> +
> +static void lp8788_led_enable(struct lp8788_led *led,
> +			enum lp8788_isink_number num, int on)
> +{
> +	u8 mask = 1 << num;
> +	u8 val = on << num;
> +
> +	if (lp8788_update_bits(led->lp, LP8788_ISINK_CTRL, mask, val))
> +		return;
> +
> +	led->on = on;
> +}
> +
> +static void lp8788_led_work(struct work_struct *work)
> +{
> +	struct lp8788_led *led = container_of(work, struct lp8788_led, work);
> +	enum lp8788_isink_number num = led->isink_num;
> +	int enable;
> +	u8 val = led->brightness;
> +
> +	mutex_lock(&led->lock);
> +
> +	switch (num) {
> +	case LP8788_ISINK_1:
> +	case LP8788_ISINK_2:
> +	case LP8788_ISINK_3:
> +		lp8788_write_byte(led->lp, lp8788_pwm_addr[num], val);
> +		break;
> +	default:
> +		return;
> +	}
> +
> +	enable = (val > 0) ? 1 : 0;
> +	if (enable != led->on)
> +		lp8788_led_enable(led, num, enable);
> +
> +	mutex_unlock(&led->lock);
> +}
> +
> +static void lp8788_brightness_set(struct led_classdev *led_cdev,
> +				enum led_brightness brt_val)
> +{
> +	struct lp8788_led *led =
> +			container_of(led_cdev, struct lp8788_led, led_dev);
> +
> +	led->brightness = brt_val;
> +	schedule_work(&led->work);
> +}
> +
> +static __devinit int lp8788_led_probe(struct platform_device *pdev)
> +{
> +	struct lp8788 *lp = dev_get_drvdata(pdev->dev.parent);
> +	struct lp8788_led_platform_data *led_pdata;
> +	struct lp8788_led *led;
> +	int ret;
> +
> +	led = devm_kzalloc(lp->dev, sizeof(struct lp8788_led), GFP_KERNEL);
> +	if (!led)
> +		return -ENOMEM;
> +
> +	led->lp = lp;
> +	led->led_dev.max_brightness = MAX_BRIGHTNESS;
> +	led->led_dev.brightness_set = lp8788_brightness_set;
> +
> +	led_pdata = lp->pdata ? lp->pdata->led_pdata : NULL;
> +
> +	if (!led_pdata || !led_pdata->name)
> +		led->led_dev.name = DEFAULT_LED_NAME;
> +	else
> +		led->led_dev.name = led_pdata->name;
> +
> +	mutex_init(&led->lock);
> +	INIT_WORK(&led->work, lp8788_led_work);
> +
> +	platform_set_drvdata(pdev, led);
> +
> +	ret = lp8788_led_init_device(led, led_pdata);
> +	if (ret) {
> +		dev_err(lp->dev, "led init device err: %d\n", ret);
> +		return ret;
> +	}
> +
> +	ret = led_classdev_register(lp->dev, &led->led_dev);
> +	if (ret) {
> +		dev_err(lp->dev, "led register err: %d\n", ret);
> +		return ret;
> +	}
> +
> +	return 0;
> +}
> +
> +static int __devexit lp8788_led_remove(struct platform_device *pdev)
> +{
> +	struct lp8788_led *led = platform_get_drvdata(pdev);
> +
> +	led_classdev_unregister(&led->led_dev);
> +	flush_work_sync(&led->work);

Is flush_work_sync() sufficient or cancel_work_sync() is a better
choice. I see some led drivers using cancel_work_sync() and some using
flush_work_sync(). I do see that flush_work_sync() doesn't do any
del_timer_sync() calls to cancel timers if any running.

> +
> +	return 0;
> +}
> +
> +static struct platform_driver lp8788_led_driver = {
> +	.probe = lp8788_led_probe,
> +	.remove = __devexit_p(lp8788_led_remove),
> +	.driver = {
> +		.name = LP8788_DEV_KEYLED,
> +		.owner = THIS_MODULE,
> +	},
> +};
> +module_platform_driver(lp8788_led_driver);
> +
> +MODULE_DESCRIPTION("Texas Instruments LP8788 Keyboard LED Driver");
> +MODULE_AUTHOR("Milo Kim");
> +MODULE_LICENSE("GPL");
> +MODULE_ALIAS("platform:lp8788-keyled");