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// SPDX-License-Identifier: GPL-2.0-only
/*
* Copyright (C) 2012 Bachmann electronic GmbH
* Christian Gmeiner <christian.gmeiner@gmail.com>
*
* Backlight driver for ot200 visualisation device from
* Bachmann electronic GmbH.
*/
#include <linux/module.h>
#include <linux/fb.h>
#include <linux/backlight.h>
#include <linux/gpio.h>
#include <linux/platform_device.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 (devm_gpio_request(&pdev->dev, 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");
return -ENODEV;
}
data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
if (!data) {
retval = -ENOMEM;
goto error_devm_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 = devm_backlight_device_register(&pdev->dev, 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_devm_kzalloc;
}
platform_set_drvdata(pdev, bl);
return 0;
error_devm_kzalloc:
cs5535_mfgpt_free_timer(pwm_timer);
return retval;
}
static int ot200_backlight_remove(struct platform_device *pdev)
{
/* 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);
return 0;
}
static struct platform_driver ot200_backlight_driver = {
.driver = {
.name = "ot200-backlight",
},
.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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