--- /dev/null
+/*
+ * Copyright (C) 2012 Bachmann electronic GmbH
+ * Christian Gmeiner <christian.gmeiner@gmail.com>
+ *
+ * Backlight driver for ot200 visualisation device from
+ * Bachmann electronic GmbH.
+ *
+ * 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/fb.h>
+#include <linux/backlight.h>
+#include <linux/gpio.h>
+#include <linux/cs5535.h>
+
+static struct cs5535_mfgpt_timer *pwm_timer;
+
+/* this array defines the mapping of brightness in % to pwm frequency */
+static const u8 dim_table[101] = {0, 0, 1, 1, 1, 1, 1, 1, 1, 2, 2, 2, 2, 2, 2,
+ 2, 2, 2, 2, 3, 3, 3, 3, 3, 3, 3, 4, 4, 4, 4,
+ 4, 5, 5, 5, 5, 6, 6, 6, 7, 7, 7, 8, 8, 9, 9,
+ 10, 10, 11, 11, 12, 12, 13, 14, 15, 15, 16,
+ 17, 18, 19, 20, 21, 22, 23, 24, 26, 27, 28,
+ 30, 31, 33, 35, 37, 39, 41, 43, 45, 47, 50,
+ 53, 55, 58, 61, 65, 68, 72, 75, 79, 84, 88,
+ 93, 97, 103, 108, 114, 120, 126, 133, 140,
+ 147, 155, 163};
+
+struct ot200_backlight_data {
+ int current_brightness;
+};
+
+#define GPIO_DIMM 27
+#define SCALE 1
+#define CMP1MODE 0x2 /* compare on GE; output high on compare
+ * greater than or equal */
+#define PWM_SETUP (SCALE | CMP1MODE << 6 | MFGPT_SETUP_CNTEN)
+#define MAX_COMP2 163
+
+static int ot200_backlight_update_status(struct backlight_device *bl)
+{
+ struct ot200_backlight_data *data = bl_get_data(bl);
+ int brightness = bl->props.brightness;
+
+ if (bl->props.state & BL_CORE_FBBLANK)
+ brightness = 0;
+
+ /* enable or disable PWM timer */
+ if (brightness == 0)
+ cs5535_mfgpt_write(pwm_timer, MFGPT_REG_SETUP, 0);
+ else if (data->current_brightness == 0) {
+ cs5535_mfgpt_write(pwm_timer, MFGPT_REG_COUNTER, 0);
+ cs5535_mfgpt_write(pwm_timer, MFGPT_REG_SETUP,
+ MFGPT_SETUP_CNTEN);
+ }
+
+ /* apply new brightness value */
+ cs5535_mfgpt_write(pwm_timer, MFGPT_REG_CMP1,
+ MAX_COMP2 - dim_table[brightness]);
+ data->current_brightness = brightness;
+
+ return 0;
+}
+
+static int ot200_backlight_get_brightness(struct backlight_device *bl)
+{
+ struct ot200_backlight_data *data = bl_get_data(bl);
+ return data->current_brightness;
+}
+
+static const struct backlight_ops ot200_backlight_ops = {
+ .update_status = ot200_backlight_update_status,
+ .get_brightness = ot200_backlight_get_brightness,
+};
+
+static int ot200_backlight_probe(struct platform_device *pdev)
+{
+ struct backlight_device *bl;
+ struct ot200_backlight_data *data;
+ struct backlight_properties props;
+ int retval = 0;
+
+ /* request gpio */
+ if (gpio_request(GPIO_DIMM, "ot200 backlight dimmer") < 0) {
+ dev_err(&pdev->dev, "failed to request GPIO %d\n", GPIO_DIMM);
+ return -ENODEV;
+ }
+
+ /* request timer */
+ pwm_timer = cs5535_mfgpt_alloc_timer(7, MFGPT_DOMAIN_ANY);
+ if (!pwm_timer) {
+ dev_err(&pdev->dev, "MFGPT 7 not available\n");
+ retval = -ENODEV;
+ goto error_mfgpt_alloc;
+ }
+
+ data = kzalloc(sizeof(*data), GFP_KERNEL);
+ if (!data) {
+ retval = -ENOMEM;
+ goto error_kzalloc;
+ }
+
+ /* setup gpio */
+ cs5535_gpio_set(GPIO_DIMM, GPIO_OUTPUT_ENABLE);
+ cs5535_gpio_set(GPIO_DIMM, GPIO_OUTPUT_AUX1);
+
+ /* setup timer */
+ cs5535_mfgpt_write(pwm_timer, MFGPT_REG_CMP1, 0);
+ cs5535_mfgpt_write(pwm_timer, MFGPT_REG_CMP2, MAX_COMP2);
+ cs5535_mfgpt_write(pwm_timer, MFGPT_REG_SETUP, PWM_SETUP);
+
+ data->current_brightness = 100;
+ props.max_brightness = 100;
+ props.brightness = 100;
+ props.type = BACKLIGHT_RAW;
+
+ bl = backlight_device_register(dev_name(&pdev->dev), &pdev->dev, data,
+ &ot200_backlight_ops, &props);
+ if (IS_ERR(bl)) {
+ dev_err(&pdev->dev, "failed to register backlight\n");
+ retval = PTR_ERR(bl);
+ goto error_backlight_device_register;
+ }
+
+ platform_set_drvdata(pdev, bl);
+
+ return 0;
+
+error_backlight_device_register:
+ kfree(data);
+error_kzalloc:
+ cs5535_mfgpt_free_timer(pwm_timer);
+error_mfgpt_alloc:
+ gpio_free(GPIO_DIMM);
+ return retval;
+}
+
+static int ot200_backlight_remove(struct platform_device *pdev)
+{
+ struct backlight_device *bl = platform_get_drvdata(pdev);
+ struct ot200_backlight_data *data = bl_get_data(bl);
+
+ backlight_device_unregister(bl);
+
+ /* on module unload set brightness to 100% */
+ cs5535_mfgpt_write(pwm_timer, MFGPT_REG_COUNTER, 0);
+ cs5535_mfgpt_write(pwm_timer, MFGPT_REG_SETUP, MFGPT_SETUP_CNTEN);
+ cs5535_mfgpt_write(pwm_timer, MFGPT_REG_CMP1,
+ MAX_COMP2 - dim_table[100]);
+
+ cs5535_mfgpt_free_timer(pwm_timer);
+ gpio_free(GPIO_DIMM);
+
+ kfree(data);
+ return 0;
+}
+
+static struct platform_driver ot200_backlight_driver = {
+ .driver = {
+ .name = "ot200-backlight",
+ .owner = THIS_MODULE,
+ },
+ .probe = ot200_backlight_probe,
+ .remove = ot200_backlight_remove,
+};
+
+module_platform_driver(ot200_backlight_driver);
+
+MODULE_DESCRIPTION("backlight driver for ot200 visualisation device");
+MODULE_AUTHOR("Christian Gmeiner <christian.gmeiner@gmail.com>");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:ot200-backlight");
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