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    Subject[PATCH] backlight: lcd: add driver for raster-type lcd's with gpio controlled panel reset
    Date
    Add a lcd panel driver for simple raster-type lcd's which uses a gpio
    controlled panel reset. The driver controls the nRESET line of the panel
    using a gpio connected from the host system. The Vcc supply to the panel
    is (optionally) controlled using a voltage regulator. This driver excludes
    support for lcd panels that use a serial command interface or direct
    memory mapped IO interface.

    Suggested-by: Lars-Peter Clausen <lars@metafoo.de>
    Signed-off-by: Thomas Abraham <thomas.abraham@linaro.org>
    ---
    .../devicetree/bindings/lcd/lcd-pwrctrl.txt | 39 ++++
    drivers/video/backlight/Kconfig | 7 +
    drivers/video/backlight/Makefile | 1 +
    drivers/video/backlight/lcd_pwrctrl.c | 231 ++++++++++++++++++++
    include/video/lcd_pwrctrl.h | 30 +++
    5 files changed, 308 insertions(+), 0 deletions(-)
    create mode 100644 Documentation/devicetree/bindings/lcd/lcd-pwrctrl.txt
    create mode 100644 drivers/video/backlight/lcd_pwrctrl.c
    create mode 100644 include/video/lcd_pwrctrl.h

    diff --git a/Documentation/devicetree/bindings/lcd/lcd-pwrctrl.txt b/Documentation/devicetree/bindings/lcd/lcd-pwrctrl.txt
    new file mode 100644
    index 0000000..941e2ff
    --- /dev/null
    +++ b/Documentation/devicetree/bindings/lcd/lcd-pwrctrl.txt
    @@ -0,0 +1,39 @@
    +* Power controller for simple lcd panels
    +
    +Some LCD panels provide a simple control interface for the host system. The
    +control mechanism would include a nRESET line connected to a gpio of the host
    +system and a Vcc supply line which the host can optionally be controlled using
    +a voltage regulator. Such simple panels do not support serial command
    +interface (such as i2c or spi) or memory-mapped-io interface.
    +
    +Required properties:
    +- compatible: should be 'lcd,powerctrl'
    +- gpios: The GPIO number of the host system used to control the nRESET line.
    + The format of the gpio specifier depends on the gpio controller of the
    + host system.
    +
    +Optional properties:
    +- lcd,pwrctrl-nreset-gpio-invert: When the nRESET line is asserted low, the
    + lcd panel is reset and stays in reset mode as long as the nRESET line is
    + asserted low. This is the default behaviour of most lcd panels. If a lcd
    + panel requires the nRESET line to be asserted high for panel reset, then
    + this property is used.
    +- lcd,pwrctrl-min-uV: If a regulator controls the Vcc voltage of the lcd panel,
    + this property specifies the minimum voltage the regulator should supply.
    + The value of this property should in in micro-volts.
    +- lcd,pwrctrl-max-uV: If a regulator controls the Vcc voltage of the lcd panel,
    + this property specifies the maximum voltage the regulator should limit to
    + on the Vcc line. The value of this property should in in micro-volts.
    +- vcc-lcd-supply: phandle of the regulator that controls the vcc supply to
    + the lcd panel.
    +
    +Example:
    +
    + lcd_pwrctrl {
    + compatible = "lcd,powerctrl";
    + gpios = <&gpe0 4 1 0 0>;
    + lcd,pwrctrl-nreset-gpio-invert;
    + lcd,pwrctrl-min-uV = <2500000>;
    + lcd,pwrctrl-max-uV = <3300000>;
    + lcd-vcc-supply - <&regulator7>;
    + };
    diff --git a/drivers/video/backlight/Kconfig b/drivers/video/backlight/Kconfig
    index 278aeaa..fc1dc17 100644
    --- a/drivers/video/backlight/Kconfig
    +++ b/drivers/video/backlight/Kconfig
    @@ -86,6 +86,13 @@ config LCD_PLATFORM
    This driver provides a platform-device registered LCD power
    control interface.

    +config LCD_PWRCTRL
    + tristate "LCD panel power control"
    + help
    + Say y here, if you have a lcd panel that allows reset and vcc to be
    + controlled by the host system, and which does not use a serial command
    + interface (such as i2c or spi) or memory-mapped-io interface.
    +
    config LCD_TOSA
    tristate "Sharp SL-6000 LCD Driver"
    depends on SPI && MACH_TOSA
    diff --git a/drivers/video/backlight/Makefile b/drivers/video/backlight/Makefile
    index fdd1fc4..944482e 100644
    --- a/drivers/video/backlight/Makefile
    +++ b/drivers/video/backlight/Makefile
    @@ -8,6 +8,7 @@ obj-$(CONFIG_LCD_LMS283GF05) += lms283gf05.o
    obj-$(CONFIG_LCD_LTV350QV) += ltv350qv.o
    obj-$(CONFIG_LCD_ILI9320) += ili9320.o
    obj-$(CONFIG_LCD_PLATFORM) += platform_lcd.o
    +obj-$(CONFIG_LCD_PWRCTRL) += lcd_pwrctrl.o
    obj-$(CONFIG_LCD_VGG2432A4) += vgg2432a4.o
    obj-$(CONFIG_LCD_TDO24M) += tdo24m.o
    obj-$(CONFIG_LCD_TOSA) += tosa_lcd.o
    diff --git a/drivers/video/backlight/lcd_pwrctrl.c b/drivers/video/backlight/lcd_pwrctrl.c
    new file mode 100644
    index 0000000..6f3110b
    --- /dev/null
    +++ b/drivers/video/backlight/lcd_pwrctrl.c
    @@ -0,0 +1,231 @@
    +/*
    + * Simple lcd panel power control driver.
    + *
    + * Copyright (c) 2011-2012 Samsung Electronics Co., Ltd.
    + * Copyright (c) 2011-2012 Linaro Ltd.
    + *
    + * This driver is for controlling power for raster type lcd panels that requires
    + * its nRESET interface line to be connected and controlled by a GPIO of the
    + * host system and the Vcc line controlled by a voltage regulator. This
    + * excludes support for lcd panels that use a serial command interface or direct
    + * memory mapped IO interface.
    + *
    + * The nRESET interface line of the panel should be connected to a gpio of the
    + * host system. The Vcc pin is controlled using a external volatage regulator.
    + * Panel backlight is not controlled by this driver.
    + *
    + * This driver is derived from platform-lcd.c which was written by
    + * Ben Dooks <ben@simtec.co.uk>
    + *
    + * 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/platform_device.h>
    +#include <linux/fb.h>
    +#include <linux/lcd.h>
    +#include <linux/gpio.h>
    +#include <linux/of.h>
    +#include <linux/of_gpio.h>
    +#include <linux/regulator/consumer.h>
    +#include <video/lcd_pwrctrl.h>
    +
    +struct lcd_pwrctrl {
    + struct device *dev;
    + struct lcd_device *lcd;
    + struct lcd_pwrctrl_data *pdata;
    + struct regulator *regulator;
    + unsigned int power;
    + unsigned int suspended:1;
    +};
    +
    +static int lcd_pwrctrl_get_power(struct lcd_device *lcd)
    +{
    + struct lcd_pwrctrl *lp = lcd_get_data(lcd);
    + return lp->power;
    +}
    +
    +static int lcd_pwrctrl_set_power(struct lcd_device *lcd, int power)
    +{
    + struct lcd_pwrctrl *lp = lcd_get_data(lcd);
    + struct lcd_pwrctrl_data *pd = lp->pdata;
    + int lcd_enable, lcd_reset;
    +
    + lcd_enable = (power == FB_BLANK_POWERDOWN || lp->suspended) ? 0 : 1;
    + lcd_reset = (pd->invert) ? !lcd_enable : lcd_enable;
    +
    + if (IS_ERR(lp->regulator))
    + goto no_regulator;
    +
    + if (lcd_enable) {
    + if ((pd->min_uV || pd->max_uV) &&
    + regulator_set_voltage(lp->regulator,
    + pd->min_uV, pd->max_uV))
    + dev_info(lp->dev,
    + "regulator voltage set failed\n");
    + if (regulator_enable(lp->regulator))
    + dev_info(lp->dev, "failed to enable regulator\n");
    + } else {
    + regulator_disable(lp->regulator);
    + }
    +
    + no_regulator:
    + gpio_direction_output(lp->pdata->gpio, lcd_reset);
    + lp->power = power;
    + return 0;
    +}
    +
    +static int lcd_pwrctrl_check_fb(struct lcd_device *lcd, struct fb_info *info)
    +{
    + struct lcd_pwrctrl *lp = lcd_get_data(lcd);
    + return lp->dev->parent == info->device;
    +}
    +
    +static struct lcd_ops lcd_pwrctrl_ops = {
    + .get_power = lcd_pwrctrl_get_power,
    + .set_power = lcd_pwrctrl_set_power,
    + .check_fb = lcd_pwrctrl_check_fb,
    +};
    +
    +#ifdef CONFIG_OF
    +static void __devinit lcd_pwrctrl_parse_dt(struct device *dev,
    + struct lcd_pwrctrl_data *pdata)
    +{
    + struct device_node *np = dev->of_node;
    +
    + pdata->gpio = of_get_gpio(np, 0);
    + if (of_get_property(np, "lcd,pwrctrl-nreset-gpio-invert", NULL))
    + pdata->invert = true;
    + of_property_read_u32(np, "lcd,pwrctrl-min-uV", &pdata->min_uV);
    + of_property_read_u32(np, "lcd,pwrctrl-max-uV", &pdata->max_uV);
    +}
    +#endif
    +
    +static int __devinit lcd_pwrctrl_probe(struct platform_device *pdev)
    +{
    + struct lcd_pwrctrl *lp;
    + struct lcd_pwrctrl_data *pdata = pdev->dev.platform_data;
    + struct device *dev = &pdev->dev;
    + int err;
    +
    +#ifdef CONFIG_OF
    + if (dev->of_node) {
    + pdata = devm_kzalloc(dev, sizeof(*pdata), GFP_KERNEL);
    + if (!pdata) {
    + dev_err(dev, "memory allocation for pdata failed\n");
    + return -ENOMEM;
    + }
    + lcd_pwrctrl_parse_dt(dev, pdata);
    + }
    +#endif
    +
    + if (!pdata) {
    + dev_err(dev, "platform data not available\n");
    + return -EINVAL;
    + }
    +
    + err = gpio_request(pdata->gpio, "LCD-nRESET");
    + if (err) {
    + dev_err(dev, "gpio [%d] request failed\n", pdata->gpio);
    + return err;
    + }
    +
    + lp = devm_kzalloc(dev, sizeof(struct lcd_pwrctrl), GFP_KERNEL);
    + if (!lp) {
    + dev_err(dev, "memory allocation failed for private data\n");
    + return -ENOMEM;
    + }
    +
    + /*
    + * If power to lcd and/or lcd interface is controlled using a regulator,
    + * get the handle to the regulator for later use during power switching.
    + */
    + lp->regulator = regulator_get(dev, "vcc-lcd");
    + if (IS_ERR(lp->regulator))
    + dev_info(dev, "could not find regulator\n");
    +
    + lp->dev = dev;
    + lp->pdata = pdata;
    + lp->lcd = lcd_device_register(dev_name(dev), dev, lp, &lcd_pwrctrl_ops);
    + if (IS_ERR(lp->lcd)) {
    + dev_err(dev, "cannot register lcd device\n");
    + regulator_put(lp->regulator);
    + return PTR_ERR(lp->lcd);
    + }
    +
    + platform_set_drvdata(pdev, lp);
    + lcd_pwrctrl_set_power(lp->lcd, FB_BLANK_NORMAL);
    + return 0;
    +}
    +
    +static int __devexit lcd_pwrctrl_remove(struct platform_device *pdev)
    +{
    + struct lcd_pwrctrl *lp = platform_get_drvdata(pdev);
    + lcd_device_unregister(lp->lcd);
    + gpio_free(lp->pdata->gpio);
    + if (!IS_ERR(lp->regulator))
    + regulator_put(lp->regulator);
    + return 0;
    +}
    +
    +#ifdef CONFIG_PM
    +static int lcd_pwrctrl_suspend(struct platform_device *pdev, pm_message_t st)
    +{
    + struct lcd_pwrctrl *lp = platform_get_drvdata(pdev);
    +
    + lp->suspended = 1;
    + lcd_pwrctrl_set_power(lp->lcd, FB_BLANK_POWERDOWN);
    + return 0;
    +}
    +
    +static int lcd_pwrctrl_resume(struct platform_device *pdev)
    +{
    + struct lcd_pwrctrl *lp = platform_get_drvdata(pdev);
    +
    + lp->suspended = 0;
    + lcd_pwrctrl_set_power(lp->lcd, FB_BLANK_UNBLANK);
    + return 0;
    +}
    +#else
    +#define lcd_pwrctrl_suspend NULL
    +#define lcd_pwrctrl_resume NULL
    +#endif /* CONFIG_PM */
    +
    +#ifdef CONFIG_OF
    +static const struct of_device_id lcd_pwrctrl_match[] = {
    + { .compatible = "lcd,powerctrl", },
    + {},
    +};
    +#endif
    +
    +static struct platform_driver lcd_pwrctrl_driver = {
    + .driver = {
    + .name = "lcd-pwrctrl",
    + .owner = THIS_MODULE,
    + .of_match_table = of_match_ptr(lcd_pwrctrl_match),
    + },
    + .probe = lcd_pwrctrl_probe,
    + .remove = lcd_pwrctrl_remove,
    + .suspend = lcd_pwrctrl_suspend,
    + .resume = lcd_pwrctrl_resume,
    +};
    +
    +static int __init lcd_pwrctrl_init(void)
    +{
    + return platform_driver_register(&lcd_pwrctrl_driver);
    +}
    +
    +static void __exit lcd_pwrctrl_cleanup(void)
    +{
    + platform_driver_unregister(&lcd_pwrctrl_driver);
    +}
    +
    +module_init(lcd_pwrctrl_init);
    +module_exit(lcd_pwrctrl_cleanup);
    +
    +MODULE_AUTHOR("Thomas Abraham <thomas.ab@samsung.com>");
    +MODULE_LICENSE("GPL v2");
    +MODULE_ALIAS("platform:lcd-pwrctrl");
    diff --git a/include/video/lcd_pwrctrl.h b/include/video/lcd_pwrctrl.h
    new file mode 100644
    index 0000000..75b6ce2
    --- /dev/null
    +++ b/include/video/lcd_pwrctrl.h
    @@ -0,0 +1,30 @@
    +/*
    + * Simple lcd panel power control driver.
    + *
    + * Copyright (c) 2011-2012 Samsung Electronics Co., Ltd.
    + * Copyright (c) 2011-2012 Linaro Ltd.
    + *
    + * This driver is derived from platform-lcd.h which was written by
    + * Ben Dooks <ben@simtec.co.uk>
    + *
    + * 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.
    + *
    +*/
    +
    +/**
    + * struct lcd_pwrctrl_data - platform data for lcd_pwrctrl driver.
    + * @gpio: GPIO number of the host system that connects to nRESET line.
    + * @invert: True, if output of gpio connected to nRESET should be inverted.
    + * @min_uV: Minimum required voltage output from the regulator. The voltage
    + * should be specified in micro-volts.
    + * @max_uV: Maximum acceptable voltage output from the regulator. The voltage
    + * should be specified in micro-volts.
    + */
    +struct lcd_pwrctrl_data {
    + int gpio;
    + bool invert;
    + int min_uV;
    + int max_uV;
    +};
    --
    1.6.6.rc2


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