forked from rrcarlosr/Jetpack
163 lines
3.6 KiB
C
163 lines
3.6 KiB
C
/*
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* Maxim DS1050 Pulse-Width Modulator/Backlight Driver
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*
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* Copyright (C) 2015-2017 NVIDIA Corporation. All rights reserved.
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms and conditions of the GNU General Public License,
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* version 2, as published by the Free Software Foundation.
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*
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* This program is distributed in the hope it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
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* more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include <linux/module.h>
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#include <linux/slab.h>
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#include <linux/i2c.h>
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#include <linux/backlight.h>
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#include <linux/err.h>
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#include <linux/of.h>
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#define DEFAULT_BL_NAME "pwm-backlight"
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#define MAX_BRIGHTNESS 255
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struct ds1050 {
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struct i2c_client *client;
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struct backlight_device *bl;
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struct device *dev;
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};
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static int ds1050_write_byte(struct ds1050 *ds, u8 data)
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{
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return i2c_smbus_write_byte(ds->client, data);
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}
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static int ds1050_bl_update_status(struct backlight_device *bl)
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{
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struct ds1050 *ds = bl_get_data(bl);
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u8 val;
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if (bl->props.state & (BL_CORE_SUSPENDED | BL_CORE_FBBLANK))
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bl->props.brightness = 0;
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val = bl->props.brightness;
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/* DS1050 is a 5-bit PWM:
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* 0b00000 - 0% duty cycle
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* ...
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* 0b11111 - 96.88% duty cycle
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* 0b100000 - 100% duty cycle
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*/
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if (val == MAX_BRIGHTNESS)
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val = 0x20;
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else
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val >>= 3; /* ignore the 3 least significant bits */
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ds1050_write_byte(ds, val);
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return 0;
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}
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static const struct backlight_ops ds1050_bl_ops = {
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.options = BL_CORE_SUSPENDRESUME,
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.update_status = ds1050_bl_update_status,
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};
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static int ds1050_backlight_register(struct ds1050 *ds)
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{
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struct backlight_device *bl;
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struct backlight_properties props;
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const char *name = DEFAULT_BL_NAME;
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memset(&props, 0, sizeof(props));
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props.type = BACKLIGHT_PLATFORM;
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props.max_brightness = MAX_BRIGHTNESS;
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props.brightness = MAX_BRIGHTNESS / 2;
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bl = devm_backlight_device_register(ds->dev, name, ds->dev, ds,
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&ds1050_bl_ops, &props);
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if (IS_ERR(bl))
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return PTR_ERR(bl);
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ds->bl = bl;
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backlight_update_status(ds->bl);
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return 0;
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}
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static void ds1050_backlight_unregister(struct ds1050 *ds)
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{
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if (!ds)
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return;
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ds->bl->props.brightness = 0;
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backlight_update_status(ds->bl);
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devm_backlight_device_unregister(ds->dev, ds->bl);
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}
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static int ds1050_probe(struct i2c_client *cl, const struct i2c_device_id *id)
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{
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struct ds1050 *ds;
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int ret = 0;
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ds = devm_kzalloc(&cl->dev, sizeof(struct ds1050), GFP_KERNEL);
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if (!ds)
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return -ENOMEM;
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ds->client = cl;
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ds->dev = &cl->dev;
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i2c_set_clientdata(cl, ds);
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ret = ds1050_backlight_register(ds);
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if (ret)
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dev_err(ds->dev,
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"failed to register backlight, err: %d\n", ret);
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return ret;
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}
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static int ds1050_remove(struct i2c_client *cl)
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{
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struct ds1050 *ds = i2c_get_clientdata(cl);
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ds1050_backlight_unregister(ds);
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devm_kfree(&cl->dev, ds);
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return 0;
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}
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static const struct of_device_id ds1050_dt_ids[] = {
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{ .compatible = "maxim,ds1050", },
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{ }
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};
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MODULE_DEVICE_TABLE(of, ds1050_dt_ids);
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static const struct i2c_device_id ds1050_ids[] = {
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{"ds1050", 0},
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{ }
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};
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MODULE_DEVICE_TABLE(i2c, ds1050_ids);
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static struct i2c_driver ds1050_driver = {
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.driver = {
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.name = "ds1050",
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.of_match_table = of_match_ptr(ds1050_dt_ids),
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},
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.probe = ds1050_probe,
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.remove = ds1050_remove,
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.id_table = ds1050_ids,
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};
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module_i2c_driver(ds1050_driver);
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MODULE_DESCRIPTION("Maxim DS1050 Backlight driver");
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MODULE_LICENSE("GPL");
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