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 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 const struct backlight_ops lp8788_bl_ops = { 180 .options = BL_CORE_SUSPENDRESUME, 181 .update_status = lp8788_bl_update_status, 182 }; 183 184 static int lp8788_backlight_register(struct lp8788_bl *bl) 185 { 186 struct backlight_device *bl_dev; 187 struct backlight_properties props; 188 struct lp8788_backlight_platform_data *pdata = bl->pdata; 189 int init_brt; 190 char *name; 191 192 props.type = BACKLIGHT_PLATFORM; 193 props.max_brightness = MAX_BRIGHTNESS; 194 195 /* Initial brightness */ 196 if (pdata) 197 init_brt = min_t(int, pdata->initial_brightness, 198 props.max_brightness); 199 else 200 init_brt = 0; 201 202 props.brightness = init_brt; 203 204 /* Backlight device name */ 205 if (!pdata || !pdata->name) 206 name = DEFAULT_BL_NAME; 207 else 208 name = pdata->name; 209 210 bl_dev = backlight_device_register(name, bl->lp->dev, bl, 211 &lp8788_bl_ops, &props); 212 if (IS_ERR(bl_dev)) 213 return PTR_ERR(bl_dev); 214 215 bl->bl_dev = bl_dev; 216 217 return 0; 218 } 219 220 static void lp8788_backlight_unregister(struct lp8788_bl *bl) 221 { 222 struct backlight_device *bl_dev = bl->bl_dev; 223 224 backlight_device_unregister(bl_dev); 225 } 226 227 static ssize_t lp8788_get_bl_ctl_mode(struct device *dev, 228 struct device_attribute *attr, char *buf) 229 { 230 struct lp8788_bl *bl = dev_get_drvdata(dev); 231 enum lp8788_bl_ctrl_mode mode = bl->mode; 232 char *strmode; 233 234 if (is_brightness_ctrl_by_pwm(mode)) 235 strmode = "PWM based"; 236 else if (is_brightness_ctrl_by_register(mode)) 237 strmode = "Register based"; 238 else 239 strmode = "Invalid mode"; 240 241 return scnprintf(buf, PAGE_SIZE, "%s\n", strmode); 242 } 243 244 static DEVICE_ATTR(bl_ctl_mode, S_IRUGO, lp8788_get_bl_ctl_mode, NULL); 245 246 static struct attribute *lp8788_attributes[] = { 247 &dev_attr_bl_ctl_mode.attr, 248 NULL, 249 }; 250 251 static const struct attribute_group lp8788_attr_group = { 252 .attrs = lp8788_attributes, 253 }; 254 255 static int lp8788_backlight_probe(struct platform_device *pdev) 256 { 257 struct lp8788 *lp = dev_get_drvdata(pdev->dev.parent); 258 struct lp8788_bl *bl; 259 int ret; 260 261 bl = devm_kzalloc(lp->dev, sizeof(struct lp8788_bl), GFP_KERNEL); 262 if (!bl) 263 return -ENOMEM; 264 265 bl->lp = lp; 266 if (lp->pdata) 267 bl->pdata = lp->pdata->bl_pdata; 268 269 platform_set_drvdata(pdev, bl); 270 271 ret = lp8788_backlight_configure(bl); 272 if (ret) { 273 dev_err(lp->dev, "backlight config err: %d\n", ret); 274 goto err_dev; 275 } 276 277 ret = lp8788_backlight_register(bl); 278 if (ret) { 279 dev_err(lp->dev, "register backlight err: %d\n", ret); 280 goto err_dev; 281 } 282 283 ret = sysfs_create_group(&pdev->dev.kobj, &lp8788_attr_group); 284 if (ret) { 285 dev_err(lp->dev, "register sysfs err: %d\n", ret); 286 goto err_sysfs; 287 } 288 289 backlight_update_status(bl->bl_dev); 290 291 return 0; 292 293 err_sysfs: 294 lp8788_backlight_unregister(bl); 295 err_dev: 296 return ret; 297 } 298 299 static int lp8788_backlight_remove(struct platform_device *pdev) 300 { 301 struct lp8788_bl *bl = platform_get_drvdata(pdev); 302 struct backlight_device *bl_dev = bl->bl_dev; 303 304 bl_dev->props.brightness = 0; 305 backlight_update_status(bl_dev); 306 sysfs_remove_group(&pdev->dev.kobj, &lp8788_attr_group); 307 lp8788_backlight_unregister(bl); 308 309 return 0; 310 } 311 312 static struct platform_driver lp8788_bl_driver = { 313 .probe = lp8788_backlight_probe, 314 .remove = lp8788_backlight_remove, 315 .driver = { 316 .name = LP8788_DEV_BACKLIGHT, 317 }, 318 }; 319 module_platform_driver(lp8788_bl_driver); 320 321 MODULE_DESCRIPTION("Texas Instruments LP8788 Backlight Driver"); 322 MODULE_AUTHOR("Milo Kim"); 323 MODULE_LICENSE("GPL"); 324 MODULE_ALIAS("platform:lp8788-backlight"); 325