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