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