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/pwm.h>
  16 #include <linux/slab.h>
  17
  18 /* Register address */
  19 #define LP8788_BL_CONFIG                0x96
  20 #define LP8788_BL_EN                    BIT(0)
  21 #define LP8788_BL_PWM_INPUT_EN          BIT(5)
  22 #define LP8788_BL_FULLSCALE_SHIFT       2
  23 #define LP8788_BL_DIM_MODE_SHIFT        1
  24 #define LP8788_BL_PWM_POLARITY_SHIFT    6
  25
  26 #define LP8788_BL_BRIGHTNESS            0x97
  27
  28 #define LP8788_BL_RAMP                  0x98
  29 #define LP8788_BL_RAMP_RISE_SHIFT       4
  30
  31 #define MAX_BRIGHTNESS                  127
  32 #define DEFAULT_BL_NAME                 "lcd-backlight"
  33
  34 struct lp8788_bl_config {
  35         enum lp8788_bl_ctrl_mode bl_mode;
  36         enum lp8788_bl_dim_mode dim_mode;
  37         enum lp8788_bl_full_scale_current full_scale;
  38         enum lp8788_bl_ramp_step rise_time;
  39         enum lp8788_bl_ramp_step fall_time;
  40         enum pwm_polarity pwm_pol;
  41 };
  42
  43 struct lp8788_bl {
  44         struct lp8788 *lp;
  45         struct backlight_device *bl_dev;
  46         struct lp8788_backlight_platform_data *pdata;
  47         enum lp8788_bl_ctrl_mode mode;
  48         struct pwm_device *pwm;
  49 };
  50
  51 static struct lp8788_bl_config default_bl_config = {
  52         .bl_mode    = LP8788_BL_REGISTER_ONLY,
  53         .dim_mode   = LP8788_DIM_EXPONENTIAL,
  54         .full_scale = LP8788_FULLSCALE_1900uA,
  55         .rise_time  = LP8788_RAMP_8192us,
  56         .fall_time  = LP8788_RAMP_8192us,
  57         .pwm_pol    = PWM_POLARITY_NORMAL,
  58 };
  59
  60 static inline bool is_brightness_ctrl_by_pwm(enum lp8788_bl_ctrl_mode mode)
  61 {
  62         return mode == LP8788_BL_COMB_PWM_BASED;
  63 }
  64
  65 static inline bool is_brightness_ctrl_by_register(enum lp8788_bl_ctrl_mode mode)
  66 {
  67         return mode == LP8788_BL_REGISTER_ONLY ||
  68                 mode == LP8788_BL_COMB_REGISTER_BASED;
  69 }
  70
  71 static int lp8788_backlight_configure(struct lp8788_bl *bl)
  72 {
  73         struct lp8788_backlight_platform_data *pdata = bl->pdata;
  74         struct lp8788_bl_config *cfg = &default_bl_config;
  75         int ret;
  76         u8 val;
  77
  78         /*
  79          * Update chip configuration if platform data exists,
  80          * otherwise use the default settings.
  81          */
  82         if (pdata) {
  83                 cfg->bl_mode    = pdata->bl_mode;
  84                 cfg->dim_mode   = pdata->dim_mode;
  85                 cfg->full_scale = pdata->full_scale;
  86                 cfg->rise_time  = pdata->rise_time;
  87                 cfg->fall_time  = pdata->fall_time;
  88                 cfg->pwm_pol    = pdata->pwm_pol;
  89         }
  90
  91         /* Brightness ramp up/down */
  92         val = (cfg->rise_time << LP8788_BL_RAMP_RISE_SHIFT) | cfg->fall_time;
  93         ret = lp8788_write_byte(bl->lp, LP8788_BL_RAMP, val);
  94         if (ret)
  95                 return ret;
  96
  97         /* Fullscale current setting */
  98         val = (cfg->full_scale << LP8788_BL_FULLSCALE_SHIFT) |
  99                 (cfg->dim_mode << LP8788_BL_DIM_MODE_SHIFT);
 100
 101         /* Brightness control mode */
 102         switch (cfg->bl_mode) {
 103         case LP8788_BL_REGISTER_ONLY:
 104                 val |= LP8788_BL_EN;
 105                 break;
 106         case LP8788_BL_COMB_PWM_BASED:
 107         case LP8788_BL_COMB_REGISTER_BASED:
 108                 val |= LP8788_BL_EN | LP8788_BL_PWM_INPUT_EN |
 109                         (cfg->pwm_pol << LP8788_BL_PWM_POLARITY_SHIFT);
 110                 break;
 111         default:
 112                 dev_err(bl->lp->dev, "invalid mode: %d\n", cfg->bl_mode);
 113                 return -EINVAL;
 114         }
 115
 116         bl->mode = cfg->bl_mode;
 117
 118         return lp8788_write_byte(bl->lp, LP8788_BL_CONFIG, val);
 119 }
 120
 121 static void lp8788_pwm_ctrl(struct lp8788_bl *bl, int br, int max_br)
 122 {
 123         unsigned int period;
 124         unsigned int duty;
 125         struct device *dev;
 126         struct pwm_device *pwm;
 127
 128         if (!bl->pdata)
 129                 return;
 130
 131         period = bl->pdata->period_ns;
 132         duty = br * period / max_br;
 133         dev = bl->lp->dev;
 134
 135         /* request PWM device with the consumer name */
 136         if (!bl->pwm) {
 137                 pwm = devm_pwm_get(dev, LP8788_DEV_BACKLIGHT);
 138                 if (IS_ERR(pwm)) {
 139                         dev_err(dev, "can not get PWM device\n");
 140                         return;
 141                 }
 142
 143                 bl->pwm = pwm;
 144
 145                 /*
 146                  * FIXME: pwm_apply_args() should be removed when switching to
 147                  * the atomic PWM API.
 148                  */
 149                 pwm_apply_args(pwm);
 150         }
 151
 152         pwm_config(bl->pwm, duty, period);
 153         if (duty)
 154                 pwm_enable(bl->pwm);
 155         else
 156                 pwm_disable(bl->pwm);
 157 }
 158
 159 static int lp8788_bl_update_status(struct backlight_device *bl_dev)
 160 {
 161         struct lp8788_bl *bl = bl_get_data(bl_dev);
 162         enum lp8788_bl_ctrl_mode mode = bl->mode;
 163
 164         if (bl_dev->props.state & BL_CORE_SUSPENDED)
 165                 bl_dev->props.brightness = 0;
 166
 167         if (is_brightness_ctrl_by_pwm(mode)) {
 168                 int brt = bl_dev->props.brightness;
 169                 int max = bl_dev->props.max_brightness;
 170
 171                 lp8788_pwm_ctrl(bl, brt, max);
 172         } else if (is_brightness_ctrl_by_register(mode)) {
 173                 u8 brt = bl_dev->props.brightness;
 174
 175                 lp8788_write_byte(bl->lp, LP8788_BL_BRIGHTNESS, brt);
 176         }
 177
 178         return 0;
 179 }
 180
 181 static const struct backlight_ops lp8788_bl_ops = {
 182         .options = BL_CORE_SUSPENDRESUME,
 183         .update_status = lp8788_bl_update_status,
 184 };
 185
 186 static int lp8788_backlight_register(struct lp8788_bl *bl)
 187 {
 188         struct backlight_device *bl_dev;
 189         struct backlight_properties props;
 190         struct lp8788_backlight_platform_data *pdata = bl->pdata;
 191         int init_brt;
 192         char *name;
 193
 194         memset(&props, 0, sizeof(struct backlight_properties));
 195         props.type = BACKLIGHT_PLATFORM;
 196         props.max_brightness = MAX_BRIGHTNESS;
 197
 198         /* Initial brightness */
 199         if (pdata)
 200                 init_brt = min_t(int, pdata->initial_brightness,
 201                                 props.max_brightness);
 202         else
 203                 init_brt = 0;
 204
 205         props.brightness = init_brt;
 206
 207         /* Backlight device name */
 208         if (!pdata || !pdata->name)
 209                 name = DEFAULT_BL_NAME;
 210         else
 211                 name = pdata->name;
 212
 213         bl_dev = backlight_device_register(name, bl->lp->dev, bl,
 214                                        &lp8788_bl_ops, &props);
 215         if (IS_ERR(bl_dev))
 216                 return PTR_ERR(bl_dev);
 217
 218         bl->bl_dev = bl_dev;
 219
 220         return 0;
 221 }
 222
 223 static void lp8788_backlight_unregister(struct lp8788_bl *bl)
 224 {
 225         struct backlight_device *bl_dev = bl->bl_dev;
 226
 227         backlight_device_unregister(bl_dev);
 228 }
 229
 230 static ssize_t lp8788_get_bl_ctl_mode(struct device *dev,
 231                                      struct device_attribute *attr, char *buf)
 232 {
 233         struct lp8788_bl *bl = dev_get_drvdata(dev);
 234         enum lp8788_bl_ctrl_mode mode = bl->mode;
 235         char *strmode;
 236
 237         if (is_brightness_ctrl_by_pwm(mode))
 238                 strmode = "PWM based";
 239         else if (is_brightness_ctrl_by_register(mode))
 240                 strmode = "Register based";
 241         else
 242                 strmode = "Invalid mode";
 243
 244         return scnprintf(buf, PAGE_SIZE, "%s\n", strmode);
 245 }
 246
 247 static DEVICE_ATTR(bl_ctl_mode, S_IRUGO, lp8788_get_bl_ctl_mode, NULL);
 248
 249 static struct attribute *lp8788_attributes[] = {
 250         &dev_attr_bl_ctl_mode.attr,
 251         NULL,
 252 };
 253
 254 static const struct attribute_group lp8788_attr_group = {
 255         .attrs = lp8788_attributes,
 256 };
 257
 258 static int lp8788_backlight_probe(struct platform_device *pdev)
 259 {
 260         struct lp8788 *lp = dev_get_drvdata(pdev->dev.parent);
 261         struct lp8788_bl *bl;
 262         int ret;
 263
 264         bl = devm_kzalloc(lp->dev, sizeof(struct lp8788_bl), GFP_KERNEL);
 265         if (!bl)
 266                 return -ENOMEM;
 267
 268         bl->lp = lp;
 269         if (lp->pdata)
 270                 bl->pdata = lp->pdata->bl_pdata;
 271
 272         platform_set_drvdata(pdev, bl);
 273
 274         ret = lp8788_backlight_configure(bl);
 275         if (ret) {
 276                 dev_err(lp->dev, "backlight config err: %d\n", ret);
 277                 goto err_dev;
 278         }
 279
 280         ret = lp8788_backlight_register(bl);
 281         if (ret) {
 282                 dev_err(lp->dev, "register backlight err: %d\n", ret);
 283                 goto err_dev;
 284         }
 285
 286         ret = sysfs_create_group(&pdev->dev.kobj, &lp8788_attr_group);
 287         if (ret) {
 288                 dev_err(lp->dev, "register sysfs err: %d\n", ret);
 289                 goto err_sysfs;
 290         }
 291
 292         backlight_update_status(bl->bl_dev);
 293
 294         return 0;
 295
 296 err_sysfs:
 297         lp8788_backlight_unregister(bl);
 298 err_dev:
 299         return ret;
 300 }
 301
 302 static int lp8788_backlight_remove(struct platform_device *pdev)
 303 {
 304         struct lp8788_bl *bl = platform_get_drvdata(pdev);
 305         struct backlight_device *bl_dev = bl->bl_dev;
 306
 307         bl_dev->props.brightness = 0;
 308         backlight_update_status(bl_dev);
 309         sysfs_remove_group(&pdev->dev.kobj, &lp8788_attr_group);
 310         lp8788_backlight_unregister(bl);
 311
 312         return 0;
 313 }
 314
 315 static struct platform_driver lp8788_bl_driver = {
 316         .probe = lp8788_backlight_probe,
 317         .remove = lp8788_backlight_remove,
 318         .driver = {
 319                 .name = LP8788_DEV_BACKLIGHT,
 320         },
 321 };
 322 module_platform_driver(lp8788_bl_driver);
 323
 324 MODULE_DESCRIPTION("Texas Instruments LP8788 Backlight Driver");
 325 MODULE_AUTHOR("Milo Kim");
 326 MODULE_LICENSE("GPL");
 327 MODULE_ALIAS("platform:lp8788-backlight");