diff options
Diffstat (limited to 'drivers/video/backlight/ot200_bl.c')
| -rw-r--r-- | drivers/video/backlight/ot200_bl.c | 175 |
1 files changed, 175 insertions, 0 deletions
diff --git a/drivers/video/backlight/ot200_bl.c b/drivers/video/backlight/ot200_bl.c new file mode 100644 index 000000000000..f519d55a294c --- /dev/null +++ b/drivers/video/backlight/ot200_bl.c @@ -0,0 +1,175 @@ +/* + * 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"); |