Kim, Milo | c5a5105 | 2013-02-27 17:02:43 -0800 | [diff] [blame] | 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 | 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 | pwm_config(bl->pwm, duty, period); |
| 151 | if (duty) |
| 152 | pwm_enable(bl->pwm); |
| 153 | else |
| 154 | pwm_disable(bl->pwm); |
| 155 | } |
| 156 | |
| 157 | static int lp8788_bl_update_status(struct backlight_device *bl_dev) |
| 158 | { |
| 159 | struct lp8788_bl *bl = bl_get_data(bl_dev); |
| 160 | enum lp8788_bl_ctrl_mode mode = bl->mode; |
| 161 | |
| 162 | if (bl_dev->props.state & BL_CORE_SUSPENDED) |
| 163 | bl_dev->props.brightness = 0; |
| 164 | |
| 165 | if (is_brightness_ctrl_by_pwm(mode)) { |
| 166 | int brt = bl_dev->props.brightness; |
| 167 | int max = bl_dev->props.max_brightness; |
| 168 | |
| 169 | lp8788_pwm_ctrl(bl, brt, max); |
| 170 | } else if (is_brightness_ctrl_by_register(mode)) { |
| 171 | u8 brt = bl_dev->props.brightness; |
| 172 | |
| 173 | lp8788_write_byte(bl->lp, LP8788_BL_BRIGHTNESS, brt); |
| 174 | } |
| 175 | |
| 176 | return 0; |
| 177 | } |
| 178 | |
| 179 | static int lp8788_bl_get_brightness(struct backlight_device *bl_dev) |
| 180 | { |
| 181 | return bl_dev->props.brightness; |
| 182 | } |
| 183 | |
| 184 | static const struct backlight_ops lp8788_bl_ops = { |
| 185 | .options = BL_CORE_SUSPENDRESUME, |
| 186 | .update_status = lp8788_bl_update_status, |
| 187 | .get_brightness = lp8788_bl_get_brightness, |
| 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 | if (bl_dev) |
| 231 | backlight_device_unregister(bl_dev); |
| 232 | } |
| 233 | |
| 234 | static ssize_t lp8788_get_bl_ctl_mode(struct device *dev, |
| 235 | struct device_attribute *attr, char *buf) |
| 236 | { |
| 237 | struct lp8788_bl *bl = dev_get_drvdata(dev); |
| 238 | enum lp8788_bl_ctrl_mode mode = bl->mode; |
| 239 | char *strmode; |
| 240 | |
| 241 | if (is_brightness_ctrl_by_pwm(mode)) |
| 242 | strmode = "PWM based"; |
| 243 | else if (is_brightness_ctrl_by_register(mode)) |
| 244 | strmode = "Register based"; |
| 245 | else |
| 246 | strmode = "Invalid mode"; |
| 247 | |
| 248 | return scnprintf(buf, PAGE_SIZE, "%s\n", strmode); |
| 249 | } |
| 250 | |
| 251 | static DEVICE_ATTR(bl_ctl_mode, S_IRUGO, lp8788_get_bl_ctl_mode, NULL); |
| 252 | |
| 253 | static struct attribute *lp8788_attributes[] = { |
| 254 | &dev_attr_bl_ctl_mode.attr, |
| 255 | NULL, |
| 256 | }; |
| 257 | |
| 258 | static const struct attribute_group lp8788_attr_group = { |
| 259 | .attrs = lp8788_attributes, |
| 260 | }; |
| 261 | |
| 262 | static int lp8788_backlight_probe(struct platform_device *pdev) |
| 263 | { |
| 264 | struct lp8788 *lp = dev_get_drvdata(pdev->dev.parent); |
| 265 | struct lp8788_bl *bl; |
| 266 | int ret; |
| 267 | |
| 268 | bl = devm_kzalloc(lp->dev, sizeof(struct lp8788_bl), GFP_KERNEL); |
| 269 | if (!bl) |
| 270 | return -ENOMEM; |
| 271 | |
| 272 | bl->lp = lp; |
| 273 | if (lp->pdata) |
| 274 | bl->pdata = lp->pdata->bl_pdata; |
| 275 | |
| 276 | platform_set_drvdata(pdev, bl); |
| 277 | |
| 278 | ret = lp8788_backlight_configure(bl); |
| 279 | if (ret) { |
| 280 | dev_err(lp->dev, "backlight config err: %d\n", ret); |
| 281 | goto err_dev; |
| 282 | } |
| 283 | |
| 284 | ret = lp8788_backlight_register(bl); |
| 285 | if (ret) { |
| 286 | dev_err(lp->dev, "register backlight err: %d\n", ret); |
| 287 | goto err_dev; |
| 288 | } |
| 289 | |
| 290 | ret = sysfs_create_group(&pdev->dev.kobj, &lp8788_attr_group); |
| 291 | if (ret) { |
| 292 | dev_err(lp->dev, "register sysfs err: %d\n", ret); |
| 293 | goto err_sysfs; |
| 294 | } |
| 295 | |
| 296 | backlight_update_status(bl->bl_dev); |
| 297 | |
| 298 | return 0; |
| 299 | |
| 300 | err_sysfs: |
| 301 | lp8788_backlight_unregister(bl); |
| 302 | err_dev: |
| 303 | return ret; |
| 304 | } |
| 305 | |
| 306 | static int lp8788_backlight_remove(struct platform_device *pdev) |
| 307 | { |
| 308 | struct lp8788_bl *bl = platform_get_drvdata(pdev); |
| 309 | struct backlight_device *bl_dev = bl->bl_dev; |
| 310 | |
| 311 | bl_dev->props.brightness = 0; |
| 312 | backlight_update_status(bl_dev); |
| 313 | sysfs_remove_group(&pdev->dev.kobj, &lp8788_attr_group); |
| 314 | lp8788_backlight_unregister(bl); |
| 315 | platform_set_drvdata(pdev, NULL); |
| 316 | |
| 317 | return 0; |
| 318 | } |
| 319 | |
| 320 | static struct platform_driver lp8788_bl_driver = { |
| 321 | .probe = lp8788_backlight_probe, |
| 322 | .remove = lp8788_backlight_remove, |
| 323 | .driver = { |
| 324 | .name = LP8788_DEV_BACKLIGHT, |
| 325 | .owner = THIS_MODULE, |
| 326 | }, |
| 327 | }; |
| 328 | module_platform_driver(lp8788_bl_driver); |
| 329 | |
| 330 | MODULE_DESCRIPTION("Texas Instruments LP8788 Backlight Driver"); |
| 331 | MODULE_AUTHOR("Milo Kim"); |
| 332 | MODULE_LICENSE("GPL"); |
| 333 | MODULE_ALIAS("platform:lp8788-backlight"); |