drivers/video/backlight/tps61163a_bl.c

   1 /*
   2  * Simple driver for Texas Instruments TPS61163A Backlight driver chip
   3  *        using EasyScale Interface
   4  *
   5  * Copyright (C) 2014 Texas Instruments
   6  * Author: Daniel Jeong  <gshark.jeong@gmail.com>
   7  *             Ldd Mlp <ldd-mlp@list.ti.com>
   8  *
   9  * This program is free software; you can redistribute it and/or modify
  10  * it under the terms of the GNU General Public License version 2 as
  11  * published by the Free Software Foundation.
  12  *
  13  */
  14
  15 #include <linux/backlight.h>
  16 #include <linux/delay.h>
  17 #include <linux/err.h>
  18 #include <linux/fb.h>
  19 #include <linux/gpio.h>
  20 #include <linux/init.h>
  21 #include <linux/kernel.h>
  22 #include <linux/module.h>
  23 #include <linux/platform_data/tps61163a_bl.h>
  24 #include <linux/platform_device.h>
  25 #include <linux/slab.h>
  26
  27 #define ADDRESS_TPS61163A       0x8F0000
  28 #define T_ES_DELAY_NS           100000
  29 #define T_ES_DETECTION_NS       260000
  30 #define T_START_NS                      2000
  31 #define T_EOS_NS                        2000
  32 #define T_RESET_MS                      3
  33 #define T_LOW_LOGIC_1_NS        3000
  34 #define T_LOW_LOGIC_0_NS        7000
  35 #define T_LOGIC_NS                      T_LOW_LOGIC_1_NS + T_LOW_LOGIC_0_NS
  36
  37 #define BRIGHTNESS_MAX          0x1ff
  38 #define BRIGHTNESS_BMASK        0x1ff
  39
  40 struct tps61163a_bl_data {
  41         struct device *dev;
  42         struct backlight_device *bled;
  43         struct tps61163a_platform_data *pdata;
  44
  45         unsigned int en_gpio;
  46 };
  47
  48 static int tps61163a_backlight_update_status(struct backlight_device *bl)
  49 {
  50         struct tps61163a_bl_data *pchip = bl_get_data(bl);
  51         unsigned int es_data, bmask;
  52
  53         es_data = ADDRESS_TPS61163A | (bl->props.brightness & BRIGHTNESS_BMASK);
  54
  55         /* t_start : 2us high before data byte */
  56         gpio_direction_output(pchip->en_gpio,1);
  57         ndelay(T_START_NS);
  58
  59         for(bmask = 0x01; bmask < 0x1000000 ; bmask <<= 1){
  60                 int t_low;
  61                 if(es_data & bmask)
  62                         t_low = T_LOW_LOGIC_1_NS;
  63                 else
  64                         t_low = T_LOW_LOGIC_0_NS;
  65
  66                 gpio_direction_output(pchip->en_gpio,0);
  67                 ndelay(t_low);
  68                 gpio_direction_output(pchip->en_gpio,1);
  69                 ndelay(T_LOGIC_NS - t_low);
  70         }
  71         gpio_direction_output(pchip->en_gpio,0);
  72         /* t_eos : 2us low after address byte */
  73         ndelay(T_EOS_NS);
  74         gpio_direction_output(pchip->en_gpio,1);
  75
  76
  77         return bl->props.brightness;
  78 }
  79
  80 static int tps61163a_backlight_get_brightness(struct backlight_device *bl)
  81 {
  82         return bl->props.brightness;
  83 }
  84
  85 static const struct backlight_ops tps61163a_bl_ops = {
  86         .update_status  = tps61163a_backlight_update_status,
  87         .get_brightness = tps61163a_backlight_get_brightness,
  88 };
  89
  90 static ssize_t tps61163a_enable_store(struct device *dev,
  91                                    struct device_attribute *devAttr,
  92                                    const char *buf, size_t size)
  93 {
  94         struct tps61163a_bl_data *pchip = dev_get_drvdata(dev);
  95         unsigned int input;
  96         int ret;
  97
  98         ret = kstrtouint(buf, 10, &input);
  99         if (ret)
 100                 return -EINVAL;
 101
 102         if(input == 0){
 103                 gpio_direction_output(pchip->en_gpio,0);
 104                 /* low more than 2.5 ms to reset */
 105                 mdelay(T_RESET_MS);
 106         } else {
 107                 gpio_direction_output(pchip->en_gpio,1);
 108                 ndelay(T_ES_DELAY_NS);
 109                 gpio_direction_output(pchip->en_gpio,0);
 110                 ndelay(T_ES_DETECTION_NS);
 111                 gpio_direction_output(pchip->en_gpio,1);
 112         }
 113
 114         return size;
 115 }
 116 static DEVICE_ATTR(enable, S_IWUSR, NULL, tps61163a_enable_store);
 117
 118 #ifdef CONFIG_OF
 119 static int tps61163a_backlight_parse_dt(struct device *dev)
 120 {
 121         struct device_node *node = dev->of_node;
 122         u32 value;
 123         int ret;
 124
 125         if (!node)
 126                 return -ENODEV;
 127
 128         ret = of_property_read_u32(node, "en_gpio_num",&value);
 129         if (ret < 0)
 130                 return ret;
 131
 132         return value;
 133 }
 134
 135 static struct of_device_id tps61163a_backlight_of_match[] = {
 136         { .compatible = TPS61163A_NAME },
 137         { }
 138 };
 139
 140 MODULE_DEVICE_TABLE(of, tps61163a_backlight_of_match);
 141 #else
 142 static int tps61163a_backlight_parse_dt(struct device *dev,
 143                                   struct platform_tps61163a_backlight_data *data)
 144 {
 145         return -ENODEV;
 146 }
 147 #endif
 148
 149 static int tps61163a_backlight_probe(struct platform_device *pdev)
 150 {
 151         struct tps61163a_bl_data *pchip;
 152         struct backlight_properties props;
 153         struct tps61163a_platform_data *pdata = dev_get_platdata(&pdev->dev);
 154         int ret;
 155
 156         pchip = devm_kzalloc(&pdev->dev,
 157                              sizeof(struct tps61163a_bl_data), GFP_KERNEL);
 158         if (pchip == NULL)
 159                 return -ENOMEM;
 160         pchip->dev = &pdev->dev;
 161
 162         if(pdata == NULL){
 163                 pdata = devm_kzalloc(&pdev->dev,
 164                              sizeof(struct tps61163a_platform_data), GFP_KERNEL);
 165                 if (pdata == NULL)
 166                         return -ENOMEM;
 167                 pdata->en_gpio_num = tps61163a_backlight_parse_dt(&pdev->dev);
 168                 if(pdata->en_gpio_num < 0)
 169                         return -EINVAL;
 170         }
 171
 172         pchip->en_gpio = pdata->en_gpio_num;
 173         pchip->pdata = pdata;
 174
 175         memset(&props, 0, sizeof(struct backlight_properties));
 176         props.brightness = BRIGHTNESS_MAX;
 177         props.max_brightness = BRIGHTNESS_MAX;
 178         props.type = BACKLIGHT_RAW;
 179         pchip->bled =
 180                 backlight_device_register(TPS61163A_NAME, pchip->dev, pchip,
 181                                               &tps61163a_bl_ops, &props);
 182                 if (IS_ERR(pchip->bled))
 183                         return PTR_ERR(pchip->bled);
 184
 185         /* for enable/disable */
 186         ret = device_create_file(&(pchip->bled->dev),
 187                                  &dev_attr_enable);
 188         if (ret < 0) {
 189                 dev_err(pchip->dev, "failed : add sysfs entries\n");
 190                 goto err_out;
 191         }
 192         platform_set_drvdata(pdev, pchip);
 193
 194         /* EasyScale init */
 195         ret = gpio_request( pchip->en_gpio,"tps61163a");
 196         if(ret ){
 197                 dev_err(pchip->dev, "failed : get gpio %d\n",pchip->en_gpio);
 198                 goto err_out;
 199         }
 200         /*
 201          * ES Detection Window
 202          *   - ES detect delay : 100us
 203          *   - ES detect time  : 260us
 204          * it should be finished in 1ms
 205          */
 206         gpio_direction_output(pchip->en_gpio,1);
 207         ndelay(T_ES_DELAY_NS);
 208         gpio_direction_output(pchip->en_gpio,0);
 209         ndelay(T_ES_DETECTION_NS);
 210         gpio_direction_output(pchip->en_gpio,1);
 211
 212         dev_info(pchip->dev,"tps61163a based on EasyScale is initialized\n");
 213         return 0;
 214
 215 err_out:
 216
 217         backlight_device_unregister(pchip->bled);
 218         return ret;
 219 }
 220
 221 static int tps61163a_backlight_remove(struct platform_device *pdev)
 222 {
 223         struct tps61163a_bl_data *pchip = platform_get_drvdata(pdev);
 224
 225         backlight_device_unregister(pchip->bled);
 226         gpio_direction_output(pchip->en_gpio,0);
 227         mdelay(T_RESET_MS);
 228         return 0;
 229 }
 230
 231 static struct platform_driver tps61163a_backlight_driver = {
 232         .driver         = {
 233                 .name           = TPS61163A_NAME,
 234                 .owner          = THIS_MODULE,
 235                 .of_match_table = of_match_ptr(tps61163a_backlight_of_match),
 236         },
 237         .probe          = tps61163a_backlight_probe,
 238         .remove         = tps61163a_backlight_remove,
 239 };
 240
 241 module_platform_driver(tps61163a_backlight_driver);
 242
 243 MODULE_DESCRIPTION("EasyScale based tps61163a Backlight Driver");
 244 MODULE_LICENSE("GPL");
 245 MODULE_ALIAS("platform:tps61163a_bl");