backlight: Add Cirrus EP93xx backlight driver
The EP9307, EP9312, and EP9315 processors include a framebuffer
peripheral. This peripheral has a dedicated pwm output called
BRIGHT that can be used to control the backlight on an LCD.
Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Signed-off-by: Richard Purdie <rpurdie@linux.intel.com>
diff --git a/drivers/video/backlight/ep93xx_bl.c b/drivers/video/backlight/ep93xx_bl.c
new file mode 100644
index 0000000..b0cc491
--- /dev/null
+++ b/drivers/video/backlight/ep93xx_bl.c
@@ -0,0 +1,160 @@
+/*
+ * Driver for the Cirrus EP93xx lcd backlight
+ *
+ * Copyright (c) 2010 H Hartley Sweeten <hsweeten@visionengravers.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.
+ *
+ * This driver controls the pulse width modulated brightness control output,
+ * BRIGHT, on the Cirrus EP9307, EP9312, and EP9315 processors.
+ */
+
+
+#include <linux/platform_device.h>
+#include <linux/io.h>
+#include <linux/fb.h>
+#include <linux/backlight.h>
+
+#include <mach/hardware.h>
+
+#define EP93XX_RASTER_REG(x) (EP93XX_RASTER_BASE + (x))
+#define EP93XX_RASTER_BRIGHTNESS EP93XX_RASTER_REG(0x20)
+
+#define EP93XX_MAX_COUNT 255
+#define EP93XX_MAX_BRIGHT 255
+#define EP93XX_DEF_BRIGHT 128
+
+struct ep93xxbl {
+ void __iomem *mmio;
+ int brightness;
+};
+
+static int ep93xxbl_set(struct backlight_device *bl, int brightness)
+{
+ struct ep93xxbl *ep93xxbl = bl_get_data(bl);
+
+ __raw_writel((brightness << 8) | EP93XX_MAX_COUNT, ep93xxbl->mmio);
+
+ ep93xxbl->brightness = brightness;
+
+ return 0;
+}
+
+static int ep93xxbl_update_status(struct backlight_device *bl)
+{
+ int brightness = bl->props.brightness;
+
+ if (bl->props.power != FB_BLANK_UNBLANK ||
+ bl->props.fb_blank != FB_BLANK_UNBLANK)
+ brightness = 0;
+
+ return ep93xxbl_set(bl, brightness);
+}
+
+static int ep93xxbl_get_brightness(struct backlight_device *bl)
+{
+ struct ep93xxbl *ep93xxbl = bl_get_data(bl);
+
+ return ep93xxbl->brightness;
+}
+
+static const struct backlight_ops ep93xxbl_ops = {
+ .update_status = ep93xxbl_update_status,
+ .get_brightness = ep93xxbl_get_brightness,
+};
+
+static int __init ep93xxbl_probe(struct platform_device *dev)
+{
+ struct ep93xxbl *ep93xxbl;
+ struct backlight_device *bl;
+ struct backlight_properties props;
+
+ ep93xxbl = devm_kzalloc(&dev->dev, sizeof(*ep93xxbl), GFP_KERNEL);
+ if (!ep93xxbl)
+ return -ENOMEM;
+
+ /*
+ * This register is located in the range already ioremap'ed by
+ * the framebuffer driver. A MFD driver seems a bit of overkill
+ * to handle this so use the static I/O mapping; this address
+ * is already virtual.
+ *
+ * NOTE: No locking is required; the framebuffer does not touch
+ * this register.
+ */
+ ep93xxbl->mmio = EP93XX_RASTER_BRIGHTNESS;
+
+ memset(&props, 0, sizeof(struct backlight_properties));
+ props.max_brightness = EP93XX_MAX_BRIGHT;
+ bl = backlight_device_register(dev->name, &dev->dev, ep93xxbl,
+ &ep93xxbl_ops, &props);
+ if (IS_ERR(bl))
+ return PTR_ERR(bl);
+
+ bl->props.brightness = EP93XX_DEF_BRIGHT;
+
+ platform_set_drvdata(dev, bl);
+
+ ep93xxbl_update_status(bl);
+
+ return 0;
+}
+
+static int ep93xxbl_remove(struct platform_device *dev)
+{
+ struct backlight_device *bl = platform_get_drvdata(dev);
+
+ backlight_device_unregister(bl);
+ platform_set_drvdata(dev, NULL);
+ return 0;
+}
+
+#ifdef CONFIG_PM
+static int ep93xxbl_suspend(struct platform_device *dev, pm_message_t state)
+{
+ struct backlight_device *bl = platform_get_drvdata(dev);
+
+ return ep93xxbl_set(bl, 0);
+}
+
+static int ep93xxbl_resume(struct platform_device *dev)
+{
+ struct backlight_device *bl = platform_get_drvdata(dev);
+
+ backlight_update_status(bl);
+ return 0;
+}
+#else
+#define ep93xxbl_suspend NULL
+#define ep93xxbl_resume NULL
+#endif
+
+static struct platform_driver ep93xxbl_driver = {
+ .driver = {
+ .name = "ep93xx-bl",
+ .owner = THIS_MODULE,
+ },
+ .probe = ep93xxbl_probe,
+ .remove = __devexit_p(ep93xxbl_remove),
+ .suspend = ep93xxbl_suspend,
+ .resume = ep93xxbl_resume,
+};
+
+static int __init ep93xxbl_init(void)
+{
+ return platform_driver_register(&ep93xxbl_driver);
+}
+module_init(ep93xxbl_init);
+
+static void __exit ep93xxbl_exit(void)
+{
+ platform_driver_unregister(&ep93xxbl_driver);
+}
+module_exit(ep93xxbl_exit);
+
+MODULE_DESCRIPTION("EP93xx Backlight Driver");
+MODULE_AUTHOR("H Hartley Sweeten <hsweeten@visionengravers.com>");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:ep93xx-bl");