drivers/video/backlight/lp8788_bl.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * TI LP8788 MFD - backlight driver
   4  *
   5  * Copyright 2012 Texas Instruments
   6  *
   7  * Author: Milo(Woogyom) Kim <milo.kim@ti.com>
   8  */
   9
  10 #include <linux/backlight.h>
  11 #include <linux/err.h>
  12 #include <linux/mfd/lp8788.h>
  13 #include <linux/module.h>
  14 #include <linux/platform_device.h>
  15 #include <linux/slab.h>
  16
  17 /* Register address */
  18 #define LP8788_BL_CONFIG                0x96
  19 #define LP8788_BL_EN                    BIT(0)
  20 #define LP8788_BL_PWM_INPUT_EN          BIT(5)
  21 #define LP8788_BL_FULLSCALE_SHIFT       2
  22 #define LP8788_BL_DIM_MODE_SHIFT        1
  23 #define LP8788_BL_PWM_POLARITY_SHIFT    6
  24
  25 #define LP8788_BL_BRIGHTNESS            0x97
  26
  27 #define LP8788_BL_RAMP                  0x98
  28 #define LP8788_BL_RAMP_RISE_SHIFT       4
  29
  30 #define MAX_BRIGHTNESS                  127
  31 #define DEFAULT_BL_NAME                 "lcd-backlight"
  32
  33 struct lp8788_bl {
  34         struct lp8788 *lp;
  35         struct backlight_device *bl_dev;
  36 };
  37
  38 static int lp8788_backlight_configure(struct lp8788_bl *bl)
  39 {
  40         int ret;
  41         u8 val;
  42
  43         /* Brightness ramp up/down */
  44         val = (LP8788_RAMP_8192us << LP8788_BL_RAMP_RISE_SHIFT) | LP8788_RAMP_8192us;
  45         ret = lp8788_write_byte(bl->lp, LP8788_BL_RAMP, val);
  46         if (ret)
  47                 return ret;
  48
  49         /* Fullscale current setting */
  50         val = (LP8788_FULLSCALE_1900uA << LP8788_BL_FULLSCALE_SHIFT) |
  51                 (LP8788_DIM_EXPONENTIAL << LP8788_BL_DIM_MODE_SHIFT);
  52
  53         /* Brightness control mode */
  54         val |= LP8788_BL_EN;
  55
  56         return lp8788_write_byte(bl->lp, LP8788_BL_CONFIG, val);
  57 }
  58
  59 static int lp8788_bl_update_status(struct backlight_device *bl_dev)
  60 {
  61         struct lp8788_bl *bl = bl_get_data(bl_dev);
  62
  63         if (bl_dev->props.state & BL_CORE_SUSPENDED)
  64                 bl_dev->props.brightness = 0;
  65
  66         lp8788_write_byte(bl->lp, LP8788_BL_BRIGHTNESS, bl_dev->props.brightness);
  67
  68         return 0;
  69 }
  70
  71 static const struct backlight_ops lp8788_bl_ops = {
  72         .options = BL_CORE_SUSPENDRESUME,
  73         .update_status = lp8788_bl_update_status,
  74 };
  75
  76 static int lp8788_backlight_register(struct lp8788_bl *bl)
  77 {
  78         struct backlight_device *bl_dev;
  79         struct backlight_properties props;
  80
  81         memset(&props, 0, sizeof(struct backlight_properties));
  82         props.type = BACKLIGHT_PLATFORM;
  83         props.max_brightness = MAX_BRIGHTNESS;
  84
  85         /* Initial brightness */
  86         props.brightness = 0;
  87
  88         /* Backlight device name */
  89         bl_dev = backlight_device_register(DEFAULT_BL_NAME, bl->lp->dev, bl,
  90                                        &lp8788_bl_ops, &props);
  91         if (IS_ERR(bl_dev))
  92                 return PTR_ERR(bl_dev);
  93
  94         bl->bl_dev = bl_dev;
  95
  96         return 0;
  97 }
  98
  99 static void lp8788_backlight_unregister(struct lp8788_bl *bl)
 100 {
 101         struct backlight_device *bl_dev = bl->bl_dev;
 102
 103         backlight_device_unregister(bl_dev);
 104 }
 105
 106 static ssize_t lp8788_get_bl_ctl_mode(struct device *dev,
 107                                      struct device_attribute *attr, char *buf)
 108 {
 109         const char *strmode = "Register based";
 110
 111         return scnprintf(buf, PAGE_SIZE, "%s\n", strmode);
 112 }
 113
 114 static DEVICE_ATTR(bl_ctl_mode, S_IRUGO, lp8788_get_bl_ctl_mode, NULL);
 115
 116 static struct attribute *lp8788_attributes[] = {
 117         &dev_attr_bl_ctl_mode.attr,
 118         NULL,
 119 };
 120
 121 static const struct attribute_group lp8788_attr_group = {
 122         .attrs = lp8788_attributes,
 123 };
 124
 125 static int lp8788_backlight_probe(struct platform_device *pdev)
 126 {
 127         struct lp8788 *lp = dev_get_drvdata(pdev->dev.parent);
 128         struct lp8788_bl *bl;
 129         int ret;
 130
 131         bl = devm_kzalloc(lp->dev, sizeof(struct lp8788_bl), GFP_KERNEL);
 132         if (!bl)
 133                 return -ENOMEM;
 134
 135         bl->lp = lp;
 136
 137         platform_set_drvdata(pdev, bl);
 138
 139         ret = lp8788_backlight_configure(bl);
 140         if (ret) {
 141                 dev_err(lp->dev, "backlight config err: %d\n", ret);
 142                 goto err_dev;
 143         }
 144
 145         ret = lp8788_backlight_register(bl);
 146         if (ret) {
 147                 dev_err(lp->dev, "register backlight err: %d\n", ret);
 148                 goto err_dev;
 149         }
 150
 151         ret = sysfs_create_group(&pdev->dev.kobj, &lp8788_attr_group);
 152         if (ret) {
 153                 dev_err(lp->dev, "register sysfs err: %d\n", ret);
 154                 goto err_sysfs;
 155         }
 156
 157         backlight_update_status(bl->bl_dev);
 158
 159         return 0;
 160
 161 err_sysfs:
 162         lp8788_backlight_unregister(bl);
 163 err_dev:
 164         return ret;
 165 }
 166
 167 static void lp8788_backlight_remove(struct platform_device *pdev)
 168 {
 169         struct lp8788_bl *bl = platform_get_drvdata(pdev);
 170         struct backlight_device *bl_dev = bl->bl_dev;
 171
 172         bl_dev->props.brightness = 0;
 173         backlight_update_status(bl_dev);
 174         sysfs_remove_group(&pdev->dev.kobj, &lp8788_attr_group);
 175         lp8788_backlight_unregister(bl);
 176 }
 177
 178 static struct platform_driver lp8788_bl_driver = {
 179         .probe = lp8788_backlight_probe,
 180         .remove = lp8788_backlight_remove,
 181         .driver = {
 182                 .name = LP8788_DEV_BACKLIGHT,
 183         },
 184 };
 185 module_platform_driver(lp8788_bl_driver);
 186
 187 MODULE_DESCRIPTION("Texas Instruments LP8788 Backlight Driver");
 188 MODULE_AUTHOR("Milo Kim");
 189 MODULE_LICENSE("GPL");
 190 MODULE_ALIAS("platform:lp8788-backlight");