1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * Copyright 2021 Google Inc. 4 * 5 * Panel driver for the Samsung ATNA33XC20 panel. This panel can't be handled 6 * by the DRM_PANEL_SIMPLE driver because its power sequencing is non-standard. 7 */ 8 9 #include <linux/backlight.h> 10 #include <linux/delay.h> 11 #include <linux/gpio/consumer.h> 12 #include <linux/iopoll.h> 13 #include <linux/module.h> 14 #include <linux/pm_runtime.h> 15 #include <linux/regulator/consumer.h> 16 17 #include <drm/display/drm_dp_aux_bus.h> 18 #include <drm/display/drm_dp_helper.h> 19 #include <drm/drm_edid.h> 20 #include <drm/drm_panel.h> 21 22 /* T3 VCC to HPD high is max 200 ms */ 23 #define HPD_MAX_MS 200 24 #define HPD_MAX_US (HPD_MAX_MS * 1000) 25 26 struct atana33xc20_panel { 27 struct drm_panel base; 28 bool prepared; 29 bool enabled; 30 bool el3_was_on; 31 32 bool no_hpd; 33 struct gpio_desc *hpd_gpio; 34 35 struct regulator *supply; 36 struct gpio_desc *el_on3_gpio; 37 struct drm_dp_aux *aux; 38 39 struct edid *edid; 40 41 ktime_t powered_off_time; 42 ktime_t powered_on_time; 43 ktime_t el_on3_off_time; 44 }; 45 46 static inline struct atana33xc20_panel *to_atana33xc20(struct drm_panel *panel) 47 { 48 return container_of(panel, struct atana33xc20_panel, base); 49 } 50 51 static void atana33xc20_wait(ktime_t start_ktime, unsigned int min_ms) 52 { 53 ktime_t now_ktime, min_ktime; 54 55 min_ktime = ktime_add(start_ktime, ms_to_ktime(min_ms)); 56 now_ktime = ktime_get_boottime(); 57 58 if (ktime_before(now_ktime, min_ktime)) 59 msleep(ktime_to_ms(ktime_sub(min_ktime, now_ktime)) + 1); 60 } 61 62 static int atana33xc20_suspend(struct device *dev) 63 { 64 struct atana33xc20_panel *p = dev_get_drvdata(dev); 65 int ret; 66 67 /* 68 * Note 3 (Example of power off sequence in detail) in spec 69 * specifies to wait 150 ms after deasserting EL3_ON before 70 * powering off. 71 */ 72 if (p->el3_was_on) 73 atana33xc20_wait(p->el_on3_off_time, 150); 74 75 drm_dp_dpcd_set_powered(p->aux, false); 76 ret = regulator_disable(p->supply); 77 if (ret) 78 return ret; 79 p->powered_off_time = ktime_get_boottime(); 80 p->el3_was_on = false; 81 82 return 0; 83 } 84 85 static int atana33xc20_resume(struct device *dev) 86 { 87 struct atana33xc20_panel *p = dev_get_drvdata(dev); 88 int hpd_asserted; 89 int ret; 90 91 /* T12 (Power off time) is min 500 ms */ 92 atana33xc20_wait(p->powered_off_time, 500); 93 94 ret = regulator_enable(p->supply); 95 if (ret) 96 return ret; 97 drm_dp_dpcd_set_powered(p->aux, true); 98 p->powered_on_time = ktime_get_boottime(); 99 100 if (p->no_hpd) { 101 msleep(HPD_MAX_MS); 102 return 0; 103 } 104 105 if (p->hpd_gpio) { 106 ret = readx_poll_timeout(gpiod_get_value_cansleep, p->hpd_gpio, 107 hpd_asserted, hpd_asserted, 108 1000, HPD_MAX_US); 109 if (hpd_asserted < 0) 110 ret = hpd_asserted; 111 112 if (ret) 113 dev_warn(dev, "Error waiting for HPD GPIO: %d\n", ret); 114 115 return ret; 116 } 117 118 if (p->aux->wait_hpd_asserted) { 119 ret = p->aux->wait_hpd_asserted(p->aux, HPD_MAX_US); 120 121 if (ret) 122 dev_warn(dev, "Controller error waiting for HPD: %d\n", ret); 123 124 return ret; 125 } 126 127 /* 128 * Note that it's possible that no_hpd is false, hpd_gpio is 129 * NULL, and wait_hpd_asserted is NULL. This is because 130 * wait_hpd_asserted() is optional even if HPD is hooked up to 131 * a dedicated pin on the eDP controller. In this case we just 132 * assume that the controller driver will wait for HPD at the 133 * right times. 134 */ 135 return 0; 136 } 137 138 static int atana33xc20_disable(struct drm_panel *panel) 139 { 140 struct atana33xc20_panel *p = to_atana33xc20(panel); 141 142 /* Disabling when already disabled is a no-op */ 143 if (!p->enabled) 144 return 0; 145 146 gpiod_set_value_cansleep(p->el_on3_gpio, 0); 147 p->el_on3_off_time = ktime_get_boottime(); 148 p->enabled = false; 149 150 /* 151 * Keep track of the fact that EL_ON3 was on but we haven't power 152 * cycled yet. This lets us know that "el_on3_off_time" is recent (we 153 * don't need to worry about ktime wraparounds) and also makes it 154 * obvious if we try to enable again without a power cycle (see the 155 * warning in atana33xc20_enable()). 156 */ 157 p->el3_was_on = true; 158 159 /* 160 * Sleeping 20 ms here (after setting the GPIO) avoids a glitch when 161 * powering off. 162 */ 163 msleep(20); 164 165 return 0; 166 } 167 168 static int atana33xc20_enable(struct drm_panel *panel) 169 { 170 struct atana33xc20_panel *p = to_atana33xc20(panel); 171 172 /* Enabling when already enabled is a no-op */ 173 if (p->enabled) 174 return 0; 175 176 /* 177 * Once EL_ON3 drops we absolutely need a power cycle before the next 178 * enable or the backlight will never come on again. The code ensures 179 * this because disable() is _always_ followed by unprepare() and 180 * unprepare() forces a suspend with pm_runtime_put_sync_suspend(), 181 * but let's track just to make sure since the requirement is so 182 * non-obvious. 183 */ 184 if (WARN_ON(p->el3_was_on)) 185 return -EIO; 186 187 /* 188 * Note 2 (Example of power on sequence in detail) in spec specifies 189 * to wait 400 ms after powering on before asserting EL3_on. 190 */ 191 atana33xc20_wait(p->powered_on_time, 400); 192 193 gpiod_set_value_cansleep(p->el_on3_gpio, 1); 194 p->enabled = true; 195 196 return 0; 197 } 198 199 static int atana33xc20_unprepare(struct drm_panel *panel) 200 { 201 struct atana33xc20_panel *p = to_atana33xc20(panel); 202 int ret; 203 204 /* Unpreparing when already unprepared is a no-op */ 205 if (!p->prepared) 206 return 0; 207 208 /* 209 * Purposely do a put_sync, don't use autosuspend. The panel's tcon 210 * seems to sometimes crash when you stop giving it data and this is 211 * the best way to ensure it will come back. 212 * 213 * NOTE: we still want autosuspend for cases where we only turn on 214 * to get the EDID or otherwise send DP AUX commands to the panel. 215 */ 216 ret = pm_runtime_put_sync_suspend(panel->dev); 217 if (ret < 0) 218 return ret; 219 p->prepared = false; 220 221 return 0; 222 } 223 224 static int atana33xc20_prepare(struct drm_panel *panel) 225 { 226 struct atana33xc20_panel *p = to_atana33xc20(panel); 227 int ret; 228 229 /* Preparing when already prepared is a no-op */ 230 if (p->prepared) 231 return 0; 232 233 ret = pm_runtime_get_sync(panel->dev); 234 if (ret < 0) { 235 pm_runtime_put_autosuspend(panel->dev); 236 return ret; 237 } 238 p->prepared = true; 239 240 return 0; 241 } 242 243 static int atana33xc20_get_modes(struct drm_panel *panel, 244 struct drm_connector *connector) 245 { 246 struct atana33xc20_panel *p = to_atana33xc20(panel); 247 struct dp_aux_ep_device *aux_ep = to_dp_aux_ep_dev(panel->dev); 248 int num = 0; 249 250 pm_runtime_get_sync(panel->dev); 251 252 if (!p->edid) 253 p->edid = drm_get_edid(connector, &aux_ep->aux->ddc); 254 num = drm_add_edid_modes(connector, p->edid); 255 256 pm_runtime_mark_last_busy(panel->dev); 257 pm_runtime_put_autosuspend(panel->dev); 258 259 return num; 260 } 261 262 static const struct drm_panel_funcs atana33xc20_funcs = { 263 .disable = atana33xc20_disable, 264 .enable = atana33xc20_enable, 265 .unprepare = atana33xc20_unprepare, 266 .prepare = atana33xc20_prepare, 267 .get_modes = atana33xc20_get_modes, 268 }; 269 270 static void atana33xc20_runtime_disable(void *data) 271 { 272 pm_runtime_disable(data); 273 } 274 275 static void atana33xc20_dont_use_autosuspend(void *data) 276 { 277 pm_runtime_dont_use_autosuspend(data); 278 } 279 280 static int atana33xc20_probe(struct dp_aux_ep_device *aux_ep) 281 { 282 struct atana33xc20_panel *panel; 283 struct device *dev = &aux_ep->dev; 284 int ret; 285 286 panel = devm_kzalloc(dev, sizeof(*panel), GFP_KERNEL); 287 if (!panel) 288 return -ENOMEM; 289 dev_set_drvdata(dev, panel); 290 291 panel->aux = aux_ep->aux; 292 293 panel->supply = devm_regulator_get(dev, "power"); 294 if (IS_ERR(panel->supply)) 295 return dev_err_probe(dev, PTR_ERR(panel->supply), 296 "Failed to get power supply\n"); 297 298 panel->el_on3_gpio = devm_gpiod_get(dev, "enable", GPIOD_OUT_LOW); 299 if (IS_ERR(panel->el_on3_gpio)) 300 return dev_err_probe(dev, PTR_ERR(panel->el_on3_gpio), 301 "Failed to get enable GPIO\n"); 302 303 panel->no_hpd = of_property_read_bool(dev->of_node, "no-hpd"); 304 if (!panel->no_hpd) { 305 panel->hpd_gpio = devm_gpiod_get_optional(dev, "hpd", GPIOD_IN); 306 if (IS_ERR(panel->hpd_gpio)) 307 return dev_err_probe(dev, PTR_ERR(panel->hpd_gpio), 308 "Failed to get HPD GPIO\n"); 309 } 310 311 pm_runtime_enable(dev); 312 ret = devm_add_action_or_reset(dev, atana33xc20_runtime_disable, dev); 313 if (ret) 314 return ret; 315 pm_runtime_set_autosuspend_delay(dev, 2000); 316 pm_runtime_use_autosuspend(dev); 317 ret = devm_add_action_or_reset(dev, atana33xc20_dont_use_autosuspend, dev); 318 if (ret) 319 return ret; 320 321 drm_panel_init(&panel->base, dev, &atana33xc20_funcs, DRM_MODE_CONNECTOR_eDP); 322 323 pm_runtime_get_sync(dev); 324 ret = drm_panel_dp_aux_backlight(&panel->base, aux_ep->aux); 325 pm_runtime_mark_last_busy(dev); 326 pm_runtime_put_autosuspend(dev); 327 if (ret) 328 return dev_err_probe(dev, ret, 329 "failed to register dp aux backlight\n"); 330 331 drm_panel_add(&panel->base); 332 333 return 0; 334 } 335 336 static void atana33xc20_remove(struct dp_aux_ep_device *aux_ep) 337 { 338 struct device *dev = &aux_ep->dev; 339 struct atana33xc20_panel *panel = dev_get_drvdata(dev); 340 341 drm_panel_remove(&panel->base); 342 drm_panel_disable(&panel->base); 343 drm_panel_unprepare(&panel->base); 344 345 kfree(panel->edid); 346 } 347 348 static void atana33xc20_shutdown(struct dp_aux_ep_device *aux_ep) 349 { 350 struct device *dev = &aux_ep->dev; 351 struct atana33xc20_panel *panel = dev_get_drvdata(dev); 352 353 drm_panel_disable(&panel->base); 354 drm_panel_unprepare(&panel->base); 355 } 356 357 static const struct of_device_id atana33xc20_dt_match[] = { 358 { .compatible = "samsung,atna33xc20", }, 359 { /* sentinal */ } 360 }; 361 MODULE_DEVICE_TABLE(of, atana33xc20_dt_match); 362 363 static const struct dev_pm_ops atana33xc20_pm_ops = { 364 SET_RUNTIME_PM_OPS(atana33xc20_suspend, atana33xc20_resume, NULL) 365 SET_SYSTEM_SLEEP_PM_OPS(pm_runtime_force_suspend, 366 pm_runtime_force_resume) 367 }; 368 369 static struct dp_aux_ep_driver atana33xc20_driver = { 370 .driver = { 371 .name = "samsung_atana33xc20", 372 .of_match_table = atana33xc20_dt_match, 373 .pm = &atana33xc20_pm_ops, 374 }, 375 .probe = atana33xc20_probe, 376 .remove = atana33xc20_remove, 377 .shutdown = atana33xc20_shutdown, 378 }; 379 380 static int __init atana33xc20_init(void) 381 { 382 return dp_aux_dp_driver_register(&atana33xc20_driver); 383 } 384 module_init(atana33xc20_init); 385 386 static void __exit atana33xc20_exit(void) 387 { 388 dp_aux_dp_driver_unregister(&atana33xc20_driver); 389 } 390 module_exit(atana33xc20_exit); 391 392 MODULE_DESCRIPTION("Samsung ATANA33XC20 Panel Driver"); 393 MODULE_LICENSE("GPL v2"); 394