Re: [PATCH] Platform: Samsung Q10 backlight driver

From: Greg KH
Date: Wed Feb 16 2011 - 19:02:01 EST


On Wed, Feb 16, 2011 at 11:30:29PM +0000, Frederick van der Wyck wrote:
> This adds backlight control on the Samsung Q10 laptop, which does not support
> the SABI interface. Also tested successfully on the Dell Latitude X200.
>
> Signed-off-by: Frederick van der Wyck <fvanderwyck@xxxxxxxxx>
> ---
> drivers/platform/x86/Kconfig | 8 ++
> drivers/platform/x86/Makefile | 1 +
> drivers/platform/x86/samsung-q10.c | 152 ++++++++++++++++++++++++++++++++++++
> 3 files changed, 161 insertions(+), 0 deletions(-)
> create mode 100644 drivers/platform/x86/samsung-q10.c
>
> The Samsung Q10 is an old model, which does not support the SABI interface, so
> the samsung-laptop driver does not work. Backlight control is not exposed via
> ACPI either. This driver works in the same way as the SMI handler triggered by
> pressing the brightness function keys. Please let me know any feedback towards
> getting this driver included.
>
> diff --git a/drivers/platform/x86/Kconfig b/drivers/platform/x86/Kconfig
> index faec777..7432817 100644
> --- a/drivers/platform/x86/Kconfig
> +++ b/drivers/platform/x86/Kconfig
> @@ -639,4 +639,12 @@ config XO1_RFKILL
> Support for enabling/disabling the WLAN interface on the OLPC XO-1
> laptop.
>
> +config SAMSUNG_Q10
> + tristate "Samsung Q10 Extras"
> + select BACKLIGHT_CLASS_DEVICE
> + default n
> + ---help---
> + This driver provides support for backlight control on Samsung Q10
> + and some other laptops, including Dell Latitude X200.
> +
> endif # X86_PLATFORM_DEVICES
> diff --git a/drivers/platform/x86/Makefile b/drivers/platform/x86/Makefile
> index 9950ccc..2cd3e52 100644
> --- a/drivers/platform/x86/Makefile
> +++ b/drivers/platform/x86/Makefile
> @@ -33,3 +33,4 @@ obj-$(CONFIG_INTEL_IPS) += intel_ips.o
> obj-$(CONFIG_GPIO_INTEL_PMIC) += intel_pmic_gpio.o
> obj-$(CONFIG_XO1_RFKILL) += xo1-rfkill.o
> obj-$(CONFIG_IBM_RTL) += ibm_rtl.o
> +obj-$(CONFIG_SAMSUNG_Q10) += samsung-q10.o
> diff --git a/drivers/platform/x86/samsung-q10.c b/drivers/platform/x86/samsung-q10.c
> new file mode 100644
> index 0000000..ec1e004
> --- /dev/null
> +++ b/drivers/platform/x86/samsung-q10.c
> @@ -0,0 +1,152 @@
> +/*
> + * Driver for Samsung Q10: controls the backlight
> + *
> + * Also works on Dell Latitude X200
> + *
> + * Copyright (c) 2011 Frederick van der Wyck <fvanderwyck@xxxxxxxxx>
> + *
> + * 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/kernel.h>
> +#include <linux/init.h>
> +#include <linux/platform_device.h>
> +#include <linux/backlight.h>
> +#include <linux/io.h>
> +
> +#define SAMSUNGQ10_BL_MAX_INTENSITY 255
> +#define SAMSUNGQ10_BL_DEFAULT_INTENSITY 185
> +
> +static int samsungq10_suspended;
> +
> +static void samsungq10_bl_send_intensity(struct backlight_device *bd)
> +{
> + int brightness = bd->props.brightness;
> +
> + if (!samsungq10_suspended) {
> + while (inb(0x64)&2)
> + ;
> + outb_p(0xbe, 0x64);
> + while (inb(0x64)&2)
> + ;
> + outb_p(0x89, 0x60);
> + while (inb(0x64)&2)
> + ;
> + outb_p(0x91, 0x60);
> + while (inb(0x64)&2)
> + ;

Potentially endless loops are not good, please timeout if you don't get
the proper value over a time.


> + outb_p((unsigned char)brightness, 0x60);
> + };
> +}
> +
> +#ifdef CONFIG_PM
> +static int samsungq10_suspend(struct platform_device *pdev, pm_message_t state)
> +{
> + samsungq10_suspended = 1;
> + return 0;
> +}
> +
> +static int samsungq10_resume(struct platform_device *pdev)
> +{
> + struct backlight_device *bd = platform_get_drvdata(pdev);
> + samsungq10_suspended = 0;
> + samsungq10_bl_send_intensity(bd);
> + return 0;
> +}
> +#else
> +#define samsungq10_suspend NULL
> +#define samsungq10_resume NULL
> +#endif
> +
> +static int samsungq10_bl_set_intensity(struct backlight_device *bd)
> +{
> + samsungq10_bl_send_intensity(bd);
> + return 0;
> +}
> +
> +static int samsungq10_bl_get_intensity(struct backlight_device *bd)
> +{
> + return 0;
> +}
> +
> +static const struct backlight_ops samsungq10_bl_ops = {
> + .get_brightness = samsungq10_bl_get_intensity,
> + .update_status = samsungq10_bl_set_intensity,
> +};
> +
> +static int __devinit samsungq10_probe(struct platform_device *pdev)
> +{
> + struct backlight_properties props;
> + struct backlight_device *bd;
> +
> + memset(&props, 0, sizeof(struct backlight_properties));
> + props.max_brightness = SAMSUNGQ10_BL_MAX_INTENSITY;
> + bd = backlight_device_register("samsungq10bl", &pdev->dev, NULL,
> + &samsungq10_bl_ops, &props);

Why the name "samsungq10bl"? Why not just "samsung"?

> + if (IS_ERR(bd))
> + return PTR_ERR(bd);
> +
> + platform_set_drvdata(pdev, bd);
> +
> + bd->props.brightness = SAMSUNGQ10_BL_DEFAULT_INTENSITY;
> + samsungq10_bl_send_intensity(bd);
> +
> + return 0;
> +}
> +
> +static int samsungq10_remove(struct platform_device *pdev)
> +{
> + struct backlight_device *bd = platform_get_drvdata(pdev);
> +
> + bd->props.brightness = SAMSUNGQ10_BL_DEFAULT_INTENSITY;
> + samsungq10_bl_send_intensity(bd);
> +
> + backlight_device_unregister(bd);
> +
> + return 0;
> +}
> +
> +static struct platform_driver samsungq10_driver = {
> + .probe = samsungq10_probe,
> + .remove = samsungq10_remove,
> + .suspend = samsungq10_suspend,
> + .resume = samsungq10_resume,
> + .driver = {
> + .name = "samsungq10",

Same with the driver name here.

> + },
> +};
> +
> +static struct platform_device *samsungq10_device;
> +
> +static int __init samsungq10_init(void)
> +{
> + int ret;
> +
> + ret = platform_driver_register(&samsungq10_driver);
> + if (ret)
> + return ret;
> + samsungq10_device = platform_device_register_simple("samsungq10", -1,
> + NULL, 0);
> + if (IS_ERR(samsungq10_device)) {
> + platform_driver_unregister(&samsungq10_driver);
> + return PTR_ERR(samsungq10_device);
> + }
> + return 0;
> +}
> +
> +static void __exit samsungq10_exit(void)
> +{
> + platform_device_unregister(samsungq10_device);
> + platform_driver_unregister(&samsungq10_driver);
> +}
> +
> +module_init(samsungq10_init);
> +module_exit(samsungq10_exit);
> +
> +MODULE_AUTHOR("Frederick van der Wyck <fvanderwyck@xxxxxxxxx>");
> +MODULE_DESCRIPTION("Samsung Q10 Driver");
> +MODULE_LICENSE("GPL");

No DMI matching to auto-load the driver and also fail to load on any
non-supported hardware?

thanks,

greg k-h
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