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    SubjectRe: [PATCH] LED: add driver for LT3593 controlled LEDs
    Hi,

    thanks for the careful review!

    On Wed, Oct 14, 2009 at 07:13:21PM +0100, Richard Purdie wrote:
    > On Wed, 2009-10-07 at 05:41 +0800, Daniel Mack wrote:
    > > The LT3593 is a step-up DC/DC converter designed to drive up to ten
    > > white LEDs in series. The current flow can be set with a control pin.
    > >
    > > This driver controls any number of such devices connected on generic
    > > GPIOs and exports the function as as platform_driver.
    > >
    > > The gpio_led platform data struct definition is reused for this purpose.
    > >
    > > Successfully tested on a PXA embedded board.
    >
    > Looks good to me, just some minor comments:
    >
    > > +
    > > +#include <linux/kernel.h>
    > > +#include <linux/init.h>
    > > +#include <linux/platform_device.h>
    > > +#include <linux/leds.h>
    > > +#include <linux/workqueue.h>
    > > +#include <linux/delay.h>
    > > +
    > > +#include <asm/gpio.h>
    >
    > Should this be <linux/gpio.h> ?

    Yep, correct. As this is taken from leds-gpio, the original version
    should need an update, too.

    > > +static void lt3593_led_work(struct work_struct *work)
    > > +{
    > > + int pulses;
    > > + struct lt3593_led_data *led_dat =
    > > + container_of(work, struct lt3593_led_data, work);
    >
    > There's a tab above which caught my eye. I'd have ignored it if I wasn't
    > mentioning the above...

    Fixed.

    > > + pulses = 32 - (led_dat->new_level * 32) / 255;
    > > +
    > > + if (pulses == 0) {
    > > + gpio_set_value_cansleep(led_dat->gpio, 0);
    > > + mdelay(1);
    > > + gpio_set_value_cansleep(led_dat->gpio, 1);
    > > + return;
    > > + }
    >
    > mdelay is frowned upon
    >
    > > + gpio_set_value_cansleep(led_dat->gpio, 1);
    > > +
    > > + while (pulses--) {
    > > + gpio_set_value_cansleep(led_dat->gpio, 0);
    > > + udelay(1);
    > > + gpio_set_value_cansleep(led_dat->gpio, 1);
    > > + udelay(1);
    > > + }
    >
    > and likewise udelay but I guess we can't do much else with this
    > hardware...
    >
    > Otherwise it looks good, just check the include please and then I'll
    > apply it.

    Thanks! New patch below.

    Daniel

    From c1024d34445d19abe53d80756b2439521ad03579 Mon Sep 17 00:00:00 2001
    From: Daniel Mack <daniel@caiaq.de>
    Date: Wed, 7 Oct 2009 04:11:40 +0800
    Subject: [PATCH] LED: add driver for LT3593 controlled LEDs

    The LT3593 is a step-up DC/DC converter designed to drive up to ten
    white LEDs in series. The current flow can be set with a control pin.

    This driver controls any number of such devices connected on generic
    GPIOs and exports the function as as platform_driver.

    The gpio_led platform data struct definition is reused for this purpose.

    Successfully tested on a PXA embedded board.

    Signed-off-by: Daniel Mack <daniel@caiaq.de>
    Cc: Richard Purdie <rpurdie@rpsys.net>
    ---
    drivers/leds/Kconfig | 8 ++
    drivers/leds/Makefile | 1 +
    drivers/leds/leds-lt3593.c | 217 ++++++++++++++++++++++++++++++++++++++++++++
    3 files changed, 226 insertions(+), 0 deletions(-)
    create mode 100644 drivers/leds/leds-lt3593.c

    diff --git a/drivers/leds/Kconfig b/drivers/leds/Kconfig
    index 7c8e712..80a183f 100644
    --- a/drivers/leds/Kconfig
    +++ b/drivers/leds/Kconfig
    @@ -229,6 +229,14 @@ config LEDS_BD2802
    This option enables support for BD2802GU RGB LED driver chips
    accessed via the I2C bus.

    +config LEDS_LT3593
    + tristate "LED driver for LT3593 controllers"
    + depends on LEDS_CLASS && GENERIC_GPIO
    + help
    + This option enables support for LEDs driven by a Linear Technology
    + LT3593 controller. This controller uses a special one-wire pulse
    + coding protocol to set the brightness.
    +
    comment "LED Triggers"

    config LEDS_TRIGGERS
    diff --git a/drivers/leds/Makefile b/drivers/leds/Makefile
    index e8cdcf7..3d79287 100644
    --- a/drivers/leds/Makefile
    +++ b/drivers/leds/Makefile
    @@ -28,6 +28,7 @@ obj-$(CONFIG_LEDS_PCA955X) += leds-pca955x.o
    obj-$(CONFIG_LEDS_DA903X) += leds-da903x.o
    obj-$(CONFIG_LEDS_WM8350) += leds-wm8350.o
    obj-$(CONFIG_LEDS_PWM) += leds-pwm.o
    +obj-$(CONFIG_LEDS_LT3593) += leds-lt3593.o

    # LED SPI Drivers
    obj-$(CONFIG_LEDS_DAC124S085) += leds-dac124s085.o
    diff --git a/drivers/leds/leds-lt3593.c b/drivers/leds/leds-lt3593.c
    new file mode 100644
    index 0000000..fee40a8
    --- /dev/null
    +++ b/drivers/leds/leds-lt3593.c
    @@ -0,0 +1,217 @@
    +/*
    + * LEDs driver for LT3593 controllers
    + *
    + * See the datasheet at http://cds.linear.com/docs/Datasheet/3593f.pdf
    + *
    + * Copyright (c) 2009 Daniel Mack <daniel@caiaq.de>
    + *
    + * Based on leds-gpio.c,
    + *
    + * Copyright (C) 2007 8D Technologies inc.
    + * Raphael Assenat <raph@8d.com>
    + * Copyright (C) 2008 Freescale Semiconductor, Inc.
    + *
    + * 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/kernel.h>
    +#include <linux/init.h>
    +#include <linux/platform_device.h>
    +#include <linux/leds.h>
    +#include <linux/workqueue.h>
    +#include <linux/delay.h>
    +#include <linux/gpio.h>
    +
    +struct lt3593_led_data {
    + struct led_classdev cdev;
    + unsigned gpio;
    + struct work_struct work;
    + u8 new_level;
    +};
    +
    +static void lt3593_led_work(struct work_struct *work)
    +{
    + int pulses;
    + struct lt3593_led_data *led_dat =
    + container_of(work, struct lt3593_led_data, work);
    +
    + /*
    + * The LT3593 resets its internal current level register to the maximum
    + * level on the first falling edge on the control pin. Each following
    + * falling edge decreases the current level by 625uA. Up to 32 pulses
    + * can be sent, so the maximum power reduction is 20mA.
    + * After a timeout of 128us, the value is taken from the register and
    + * applied is to the output driver.
    + */
    +
    + if (led_dat->new_level == 0) {
    + gpio_set_value_cansleep(led_dat->gpio, 0);
    + return;
    + }
    +
    + pulses = 32 - (led_dat->new_level * 32) / 255;
    +
    + if (pulses == 0) {
    + gpio_set_value_cansleep(led_dat->gpio, 0);
    + mdelay(1);
    + gpio_set_value_cansleep(led_dat->gpio, 1);
    + return;
    + }
    +
    + gpio_set_value_cansleep(led_dat->gpio, 1);
    +
    + while (pulses--) {
    + gpio_set_value_cansleep(led_dat->gpio, 0);
    + udelay(1);
    + gpio_set_value_cansleep(led_dat->gpio, 1);
    + udelay(1);
    + }
    +}
    +
    +static void lt3593_led_set(struct led_classdev *led_cdev,
    + enum led_brightness value)
    +{
    + struct lt3593_led_data *led_dat =
    + container_of(led_cdev, struct lt3593_led_data, cdev);
    +
    + led_dat->new_level = value;
    + schedule_work(&led_dat->work);
    +}
    +
    +static int __devinit create_lt3593_led(const struct gpio_led *template,
    + struct lt3593_led_data *led_dat, struct device *parent)
    +{
    + int ret, state;
    +
    + /* skip leds on GPIOs that aren't available */
    + if (!gpio_is_valid(template->gpio)) {
    + printk(KERN_INFO "%s: skipping unavailable LT3593 LED at gpio %d (%s)\n",
    + KBUILD_MODNAME, template->gpio, template->name);
    + return 0;
    + }
    +
    + ret = gpio_request(template->gpio, template->name);
    + if (ret < 0)
    + return ret;
    +
    + led_dat->cdev.name = template->name;
    + led_dat->cdev.default_trigger = template->default_trigger;
    + led_dat->gpio = template->gpio;
    +
    + led_dat->cdev.brightness_set = lt3593_led_set;
    +
    + state = (template->default_state == LEDS_GPIO_DEFSTATE_ON);
    + led_dat->cdev.brightness = state ? LED_FULL : LED_OFF;
    +
    + if (!template->retain_state_suspended)
    + led_dat->cdev.flags |= LED_CORE_SUSPENDRESUME;
    +
    + ret = gpio_direction_output(led_dat->gpio, state);
    + if (ret < 0)
    + goto err;
    +
    + INIT_WORK(&led_dat->work, lt3593_led_work);
    +
    + ret = led_classdev_register(parent, &led_dat->cdev);
    + if (ret < 0)
    + goto err;
    +
    + printk(KERN_INFO "%s: registered LT3593 LED '%s' at GPIO %d\n",
    + KBUILD_MODNAME, template->name, template->gpio);
    +
    + return 0;
    +
    +err:
    + gpio_free(led_dat->gpio);
    + return ret;
    +}
    +
    +static void delete_lt3593_led(struct lt3593_led_data *led)
    +{
    + if (!gpio_is_valid(led->gpio))
    + return;
    +
    + led_classdev_unregister(&led->cdev);
    + cancel_work_sync(&led->work);
    + gpio_free(led->gpio);
    +}
    +
    +static int __devinit lt3593_led_probe(struct platform_device *pdev)
    +{
    + struct gpio_led_platform_data *pdata = pdev->dev.platform_data;
    + struct lt3593_led_data *leds_data;
    + int i, ret = 0;
    +
    + if (!pdata)
    + return -EBUSY;
    +
    + leds_data = kzalloc(sizeof(struct lt3593_led_data) * pdata->num_leds,
    + GFP_KERNEL);
    + if (!leds_data)
    + return -ENOMEM;
    +
    + for (i = 0; i < pdata->num_leds; i++) {
    + ret = create_lt3593_led(&pdata->leds[i], &leds_data[i],
    + &pdev->dev);
    + if (ret < 0)
    + goto err;
    + }
    +
    + platform_set_drvdata(pdev, leds_data);
    +
    + return 0;
    +
    +err:
    + for (i = i - 1; i >= 0; i--)
    + delete_lt3593_led(&leds_data[i]);
    +
    + kfree(leds_data);
    +
    + return ret;
    +}
    +
    +static int __devexit lt3593_led_remove(struct platform_device *pdev)
    +{
    + int i;
    + struct gpio_led_platform_data *pdata = pdev->dev.platform_data;
    + struct lt3593_led_data *leds_data;
    +
    + leds_data = platform_get_drvdata(pdev);
    +
    + for (i = 0; i < pdata->num_leds; i++)
    + delete_lt3593_led(&leds_data[i]);
    +
    + kfree(leds_data);
    +
    + return 0;
    +}
    +
    +static struct platform_driver lt3593_led_driver = {
    + .probe = lt3593_led_probe,
    + .remove = __devexit_p(lt3593_led_remove),
    + .driver = {
    + .name = "leds-lt3593",
    + .owner = THIS_MODULE,
    + },
    +};
    +
    +MODULE_ALIAS("platform:leds-lt3593");
    +
    +static int __init lt3593_led_init(void)
    +{
    + return platform_driver_register(&lt3593_led_driver);
    +}
    +
    +static void __exit lt3593_led_exit(void)
    +{
    + platform_driver_unregister(&lt3593_led_driver);
    +}
    +
    +module_init(lt3593_led_init);
    +module_exit(lt3593_led_exit);
    +
    +MODULE_AUTHOR("Daniel Mack <daniel@caiaq.de>");
    +MODULE_DESCRIPTION("LED driver for LT3593 controllers");
    +MODULE_LICENSE("GPL");
    --
    1.6.0.4


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