fbdev: LCD backlight driver using Atmel PWM driver

This patch adds a platform driver using the ATMEL PWM driver to control a
backlight which requires a PWM signal and optional GPIO signal for discrete
on/off signal.  It has been tested on Favr-32 board from EarthLCD.

The driver is configurable by supplying a struct with the platform data.  See
the include/linux/atmel-pwm-bl.h for details.

The board code for Favr-32 will be submitted to the AVR32 kernel list.

Signed-off-by: Hans-Christian Egtvedt <hans-christian.egtvedt@atmel.com>
Cc: Krzysztof Helt <krzysztof.h1@poczta.fm>
Cc: Haavard Skinnemoen <hskinnemoen@atmel.com>
Cc: Richard Purdie <rpurdie@rpsys.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 43 insertions, 0 deletions

diff --git a/include/linux/atmel-pwm-bl.h b/include/linux/atmel-pwm-bl.h
new file mode 100644
index 000000000000..0153a47806c2
--- /dev/null
+++ b/include/linux/atmel-pwm-bl.h
@@ -0,0 +1,43 @@
+/*
+ * Copyright (C) 2007 Atmel Corporation
+ *
+ * Driver for the AT32AP700X PS/2 controller (PSIF).
+ *
+ * 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.
+ */
+
+#ifndef __INCLUDE_ATMEL_PWM_BL_H
+#define __INCLUDE_ATMEL_PWM_BL_H
+
+/**
+ * struct atmel_pwm_bl_platform_data
+ * @pwm_channel: which PWM channel in the PWM module to use.
+ * @pwm_frequency: PWM frequency to generate, the driver will try to be as
+ *      close as the prescaler allows.
+ * @pwm_compare_max: value to use in the PWM channel compare register.
+ * @pwm_duty_max: maximum duty cycle value, must be less than or equal to
+ *      pwm_compare_max.
+ * @pwm_duty_min: minimum duty cycle value, must be less than pwm_duty_max.
+ * @pwm_active_low: set to one if the low part of the PWM signal increases the
+ *      brightness of the backlight.
+ * @gpio_on: GPIO line to control the backlight on/off, set to -1 if not used.
+ * @on_active_low: set to one if the on/off signal is on when GPIO is low.
+ *
+ * This struct must be added to the platform device in the board code. It is
+ * used by the atmel-pwm-bl driver to setup the GPIO to control on/off and the
+ * PWM device.
+ */
+struct atmel_pwm_bl_platform_data {
+        unsigned int pwm_channel;
+        unsigned int pwm_frequency;
+        unsigned int pwm_compare_max;
+        unsigned int pwm_duty_max;
+        unsigned int pwm_duty_min;
+        unsigned int pwm_active_low;
+        int gpio_on;
+        unsigned int on_active_low;
+};
+
+#endif /* __INCLUDE_ATMEL_PWM_BL_H */