drivers/video/backlight/lp8788_bl.c

   1 /*
   2  * TI LP8788 MFD - backlight driver
   3  *
   4  * Copyright 2012 Texas Instruments
   5  *
   6  * Author: Milo(Woogyom) Kim <milo.kim@ti.com>
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License version 2 as
  10  * published by the Free Software Foundation.
  11  *
  12  */
  13
  14 #include <linux/backlight.h>
  15 #include <linux/err.h>
  16 #include <linux/mfd/lp8788.h>
  17 #include <linux/module.h>
  18 #include <linux/platform_device.h>
  19 #include <linux/pwm.h>
  20 #include <linux/slab.h>
  21
  22 /* Register address */
  23 #define LP8788_BL_CONFIG                0x96
  24 #define LP8788_BL_EN                    BIT(0)
  25 #define LP8788_BL_PWM_INPUT_EN          BIT(5)
  26 #define LP8788_BL_FULLSCALE_SHIFT       2
  27 #define LP8788_BL_DIM_MODE_SHIFT        1
  28 #define LP8788_BL_PWM_POLARITY_SHIFT    6
  29
  30 #define LP8788_BL_BRIGHTNESS            0x97
  31
  32 #define LP8788_BL_RAMP                  0x98
  33 #define LP8788_BL_RAMP_RISE_SHIFT       4
  34
  35 #define MAX_BRIGHTNESS                  127
  36 #define DEFAULT_BL_NAME                 "lcd-backlight"
  37
  38 struct lp8788_bl_config {
  39         enum lp8788_bl_ctrl_mode bl_mode;
  40         enum lp8788_bl_dim_mode dim_mode;
  41         enum lp8788_bl_full_scale_current full_scale;
  42         enum lp8788_bl_ramp_step rise_time;
  43         enum lp8788_bl_ramp_step fall_time;
  44         enum pwm_polarity pwm_pol;
  45 };
  46
  47 struct lp8788_bl {
  48         struct lp8788 *lp;
  49         struct backlight_device *bl_dev;
  50         struct lp8788_backlight_platform_data *pdata;
  51         enum lp8788_bl_ctrl_mode mode;
  52         struct pwm_device *pwm;
  53 };
  54
  55 static struct lp8788_bl_config default_bl_config = {
  56         .bl_mode    = LP8788_BL_REGISTER_ONLY,
  57         .dim_mode   = LP8788_DIM_EXPONENTIAL,
  58         .full_scale = LP8788_FULLSCALE_1900uA,
  59         .rise_time  = LP8788_RAMP_8192us,
  60         .fall_time  = LP8788_RAMP_8192us,
  61         .pwm_pol    = PWM_POLARITY_NORMAL,
  62 };
  63
  64 static inline bool is_brightness_ctrl_by_pwm(enum lp8788_bl_ctrl_mode mode)
  65 {
  66         return mode == LP8788_BL_COMB_PWM_BASED;
  67 }
  68
  69 static inline bool is_brightness_ctrl_by_register(enum lp8788_bl_ctrl_mode mode)
  70 {
  71         return mode == LP8788_BL_REGISTER_ONLY ||
  72                 mode == LP8788_BL_COMB_REGISTER_BASED;
  73 }
  74
  75 static int lp8788_backlight_configure(struct lp8788_bl *bl)
  76 {
  77         struct lp8788_backlight_platform_data *pdata = bl->pdata;
  78         struct lp8788_bl_config *cfg = &default_bl_config;
  79         int ret;
  80         u8 val;
  81
  82         /*
  83          * Update chip configuration if platform data exists,
  84          * otherwise use the default settings.
  85          */
  86         if (pdata) {
  87                 cfg->bl_mode    = pdata->bl_mode;
  88                 cfg->dim_mode   = pdata->dim_mode;
  89                 cfg->full_scale = pdata->full_scale;
  90                 cfg->rise_time  = pdata->rise_time;
  91                 cfg->fall_time  = pdata->fall_time;
  92                 cfg->pwm_pol    = pdata->pwm_pol;
  93         }
  94
  95         /* Brightness ramp up/down */
  96         val = (cfg->rise_time << LP8788_BL_RAMP_RISE_SHIFT) | cfg->fall_time;
  97         ret = lp8788_write_byte(bl->lp, LP8788_BL_RAMP, val);
  98         if (ret)
  99                 return ret;
 100
 101         /* Fullscale current setting */
 102         val = (cfg->full_scale << LP8788_BL_FULLSCALE_SHIFT) |
 103                 (cfg->dim_mode << LP8788_BL_DIM_MODE_SHIFT);
 104
 105         /* Brightness control mode */
 106         switch (cfg->bl_mode) {
 107         case LP8788_BL_REGISTER_ONLY:
 108                 val |= LP8788_BL_EN;
 109                 break;
 110         case LP8788_BL_COMB_PWM_BASED:
 111         case LP8788_BL_COMB_REGISTER_BASED:
 112                 val |= LP8788_BL_EN | LP8788_BL_PWM_INPUT_EN |
 113                         (cfg->pwm_pol << LP8788_BL_PWM_POLARITY_SHIFT);
 114                 break;
 115         default:
 116                 dev_err(bl->lp->dev, "invalid mode: %d\n", cfg->bl_mode);
 117                 return -EINVAL;
 118         }
 119
 120         bl->mode = cfg->bl_mode;
 121
 122         return lp8788_write_byte(bl->lp, LP8788_BL_CONFIG, val);
 123 }
 124
 125 static void lp8788_pwm_ctrl(struct lp8788_bl *bl, int br, int max_br)
 126 {
 127         unsigned int period;
 128         unsigned int duty;
 129         struct device *dev;
 130         struct pwm_device *pwm;
 131
 132         if (!bl->pdata)
 133                 return;
 134
 135         period = bl->pdata->period_ns;
 136         duty = br * period / max_br;
 137         dev = bl->lp->dev;
 138
 139         /* request PWM device with the consumer name */
 140         if (!bl->pwm) {
 141                 pwm = devm_pwm_get(dev, LP8788_DEV_BACKLIGHT);
 142                 if (IS_ERR(pwm)) {
 143                         dev_err(dev, "can not get PWM device\n");
 144                         return;
 145                 }
 146
 147                 bl->pwm = pwm;
 148
 149                 /*
 150                  * FIXME: pwm_apply_args() should be removed when switching to
 151                  * the atomic PWM API.
 152                  */
 153                 pwm_apply_args(pwm);
 154         }
 155
 156         pwm_config(bl->pwm, duty, period);
 157         if (duty)
 158                 pwm_enable(bl->pwm);
 159         else
 160                 pwm_disable(bl->pwm);
 161 }
 162
 163 static int lp8788_bl_update_status(struct backlight_device *bl_dev)
 164 {
 165         struct lp8788_bl *bl = bl_get_data(bl_dev);
 166         enum lp8788_bl_ctrl_mode mode = bl->mode;
 167
 168         if (bl_dev->props.state & BL_CORE_SUSPENDED)
 169                 bl_dev->props.brightness = 0;
 170
 171         if (is_brightness_ctrl_by_pwm(mode)) {
 172                 int brt = bl_dev->props.brightness;
 173                 int max = bl_dev->props.max_brightness;
 174
 175                 lp8788_pwm_ctrl(bl, brt, max);
 176         } else if (is_brightness_ctrl_by_register(mode)) {
 177                 u8 brt = bl_dev->props.brightness;
 178
 179                 lp8788_write_byte(bl->lp, LP8788_BL_BRIGHTNESS, brt);
 180         }
 181
 182         return 0;
 183 }
 184
 185 static const struct backlight_ops lp8788_bl_ops = {
 186         .options = BL_CORE_SUSPENDRESUME,
 187         .update_status = lp8788_bl_update_status,
 188 };
 189
 190 static int lp8788_backlight_register(struct lp8788_bl *bl)
 191 {
 192         struct backlight_device *bl_dev;
 193         struct backlight_properties props;
 194         struct lp8788_backlight_platform_data *pdata = bl->pdata;
 195         int init_brt;
 196         char *name;
 197
 198         props.type = BACKLIGHT_PLATFORM;
 199         props.max_brightness = MAX_BRIGHTNESS;
 200
 201         /* Initial brightness */
 202         if (pdata)
 203                 init_brt = min_t(int, pdata->initial_brightness,
 204                                 props.max_brightness);
 205         else
 206                 init_brt = 0;
 207
 208         props.brightness = init_brt;
 209
 210         /* Backlight device name */
 211         if (!pdata || !pdata->name)
 212                 name = DEFAULT_BL_NAME;
 213         else
 214                 name = pdata->name;
 215
 216         bl_dev = backlight_device_register(name, bl->lp->dev, bl,
 217                                        &lp8788_bl_ops, &props);
 218         if (IS_ERR(bl_dev))
 219                 return PTR_ERR(bl_dev);
 220
 221         bl->bl_dev = bl_dev;
 222
 223         return 0;
 224 }
 225
 226 static void lp8788_backlight_unregister(struct lp8788_bl *bl)
 227 {
 228         struct backlight_device *bl_dev = bl->bl_dev;
 229
 230         backlight_device_unregister(bl_dev);
 231 }
 232
 233 static ssize_t lp8788_get_bl_ctl_mode(struct device *dev,
 234                                      struct device_attribute *attr, char *buf)
 235 {
 236         struct lp8788_bl *bl = dev_get_drvdata(dev);
 237         enum lp8788_bl_ctrl_mode mode = bl->mode;
 238         char *strmode;
 239
 240         if (is_brightness_ctrl_by_pwm(mode))
 241                 strmode = "PWM based";
 242         else if (is_brightness_ctrl_by_register(mode))
 243                 strmode = "Register based";
 244         else
 245                 strmode = "Invalid mode";
 246
 247         return scnprintf(buf, PAGE_SIZE, "%s\n", strmode);
 248 }
 249
 250 static DEVICE_ATTR(bl_ctl_mode, S_IRUGO, lp8788_get_bl_ctl_mode, NULL);
 251
 252 static struct attribute *lp8788_attributes[] = {
 253         &dev_attr_bl_ctl_mode.attr,
 254         NULL,
 255 };
 256
 257 static const struct attribute_group lp8788_attr_group = {
 258         .attrs = lp8788_attributes,
 259 };
 260
 261 static int lp8788_backlight_probe(struct platform_device *pdev)
 262 {
 263         struct lp8788 *lp = dev_get_drvdata(pdev->dev.parent);
 264         struct lp8788_bl *bl;
 265         int ret;
 266
 267         bl = devm_kzalloc(lp->dev, sizeof(struct lp8788_bl), GFP_KERNEL);
 268         if (!bl)
 269                 return -ENOMEM;
 270
 271         bl->lp = lp;
 272         if (lp->pdata)
 273                 bl->pdata = lp->pdata->bl_pdata;
 274
 275         platform_set_drvdata(pdev, bl);
 276
 277         ret = lp8788_backlight_configure(bl);
 278         if (ret) {
 279                 dev_err(lp->dev, "backlight config err: %d\n", ret);
 280                 goto err_dev;
 281         }
 282
 283         ret = lp8788_backlight_register(bl);
 284         if (ret) {
 285                 dev_err(lp->dev, "register backlight err: %d\n", ret);
 286                 goto err_dev;
 287         }
 288
 289         ret = sysfs_create_group(&pdev->dev.kobj, &lp8788_attr_group);
 290         if (ret) {
 291                 dev_err(lp->dev, "register sysfs err: %d\n", ret);
 292                 goto err_sysfs;
 293         }
 294
 295         backlight_update_status(bl->bl_dev);
 296
 297         return 0;
 298
 299 err_sysfs:
 300         lp8788_backlight_unregister(bl);
 301 err_dev:
 302         return ret;
 303 }
 304
 305 static int lp8788_backlight_remove(struct platform_device *pdev)
 306 {
 307         struct lp8788_bl *bl = platform_get_drvdata(pdev);
 308         struct backlight_device *bl_dev = bl->bl_dev;
 309
 310         bl_dev->props.brightness = 0;
 311         backlight_update_status(bl_dev);
 312         sysfs_remove_group(&pdev->dev.kobj, &lp8788_attr_group);
 313         lp8788_backlight_unregister(bl);
 314
 315         return 0;
 316 }
 317
 318 static struct platform_driver lp8788_bl_driver = {
 319         .probe = lp8788_backlight_probe,
 320         .remove = lp8788_backlight_remove,
 321         .driver = {
 322                 .name = LP8788_DEV_BACKLIGHT,
 323         },
 324 };
 325 module_platform_driver(lp8788_bl_driver);
 326
 327 MODULE_DESCRIPTION("Texas Instruments LP8788 Backlight Driver");
 328 MODULE_AUTHOR("Milo Kim");
 329 MODULE_LICENSE("GPL");
 330 MODULE_ALIAS("platform:lp8788-backlight");