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
to_atana33xc20(struct drm_panel * panel)46 static inline struct atana33xc20_panel *to_atana33xc20(struct drm_panel *panel)
47 {
48 return container_of(panel, struct atana33xc20_panel, base);
49 }
50
atana33xc20_wait(ktime_t start_ktime,unsigned int min_ms)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
atana33xc20_suspend(struct device * dev)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
atana33xc20_resume(struct device * dev)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 goto error;
115 }
116 } else if (p->aux->wait_hpd_asserted) {
117 ret = p->aux->wait_hpd_asserted(p->aux, HPD_MAX_US);
118
119 if (ret) {
120 dev_warn(dev, "Controller error waiting for HPD: %d\n", ret);
121 goto error;
122 }
123 }
124
125 /*
126 * Note that it's possible that no_hpd is false, hpd_gpio is
127 * NULL, and wait_hpd_asserted is NULL. This is because
128 * wait_hpd_asserted() is optional even if HPD is hooked up to
129 * a dedicated pin on the eDP controller. In this case we just
130 * assume that the controller driver will wait for HPD at the
131 * right times.
132 */
133 return 0;
134
135 error:
136 drm_dp_dpcd_set_powered(p->aux, false);
137 regulator_disable(p->supply);
138
139 return ret;
140 }
141
atana33xc20_disable(struct drm_panel * panel)142 static int atana33xc20_disable(struct drm_panel *panel)
143 {
144 struct atana33xc20_panel *p = to_atana33xc20(panel);
145
146 /* Disabling when already disabled is a no-op */
147 if (!p->enabled)
148 return 0;
149
150 gpiod_set_value_cansleep(p->el_on3_gpio, 0);
151 p->el_on3_off_time = ktime_get_boottime();
152 p->enabled = false;
153
154 /*
155 * Keep track of the fact that EL_ON3 was on but we haven't power
156 * cycled yet. This lets us know that "el_on3_off_time" is recent (we
157 * don't need to worry about ktime wraparounds) and also makes it
158 * obvious if we try to enable again without a power cycle (see the
159 * warning in atana33xc20_enable()).
160 */
161 p->el3_was_on = true;
162
163 /*
164 * Sleeping 20 ms here (after setting the GPIO) avoids a glitch when
165 * powering off.
166 */
167 msleep(20);
168
169 return 0;
170 }
171
atana33xc20_enable(struct drm_panel * panel)172 static int atana33xc20_enable(struct drm_panel *panel)
173 {
174 struct atana33xc20_panel *p = to_atana33xc20(panel);
175
176 /* Enabling when already enabled is a no-op */
177 if (p->enabled)
178 return 0;
179
180 /*
181 * Once EL_ON3 drops we absolutely need a power cycle before the next
182 * enable or the backlight will never come on again. The code ensures
183 * this because disable() is _always_ followed by unprepare() and
184 * unprepare() forces a suspend with pm_runtime_put_sync_suspend(),
185 * but let's track just to make sure since the requirement is so
186 * non-obvious.
187 */
188 if (WARN_ON(p->el3_was_on))
189 return -EIO;
190
191 /*
192 * Note 2 (Example of power on sequence in detail) in spec specifies
193 * to wait 400 ms after powering on before asserting EL3_on.
194 */
195 atana33xc20_wait(p->powered_on_time, 400);
196
197 gpiod_set_value_cansleep(p->el_on3_gpio, 1);
198 p->enabled = true;
199
200 return 0;
201 }
202
atana33xc20_unprepare(struct drm_panel * panel)203 static int atana33xc20_unprepare(struct drm_panel *panel)
204 {
205 struct atana33xc20_panel *p = to_atana33xc20(panel);
206 int ret;
207
208 /* Unpreparing when already unprepared is a no-op */
209 if (!p->prepared)
210 return 0;
211
212 /*
213 * Purposely do a put_sync, don't use autosuspend. The panel's tcon
214 * seems to sometimes crash when you stop giving it data and this is
215 * the best way to ensure it will come back.
216 *
217 * NOTE: we still want autosuspend for cases where we only turn on
218 * to get the EDID or otherwise send DP AUX commands to the panel.
219 */
220 ret = pm_runtime_put_sync_suspend(panel->dev);
221 if (ret < 0)
222 return ret;
223 p->prepared = false;
224
225 return 0;
226 }
227
atana33xc20_prepare(struct drm_panel * panel)228 static int atana33xc20_prepare(struct drm_panel *panel)
229 {
230 struct atana33xc20_panel *p = to_atana33xc20(panel);
231 int ret;
232
233 /* Preparing when already prepared is a no-op */
234 if (p->prepared)
235 return 0;
236
237 ret = pm_runtime_get_sync(panel->dev);
238 if (ret < 0) {
239 pm_runtime_put_autosuspend(panel->dev);
240 return ret;
241 }
242 p->prepared = true;
243
244 return 0;
245 }
246
atana33xc20_get_modes(struct drm_panel * panel,struct drm_connector * connector)247 static int atana33xc20_get_modes(struct drm_panel *panel,
248 struct drm_connector *connector)
249 {
250 struct atana33xc20_panel *p = to_atana33xc20(panel);
251 struct dp_aux_ep_device *aux_ep = to_dp_aux_ep_dev(panel->dev);
252 int num = 0;
253
254 pm_runtime_get_sync(panel->dev);
255
256 if (!p->edid)
257 p->edid = drm_get_edid(connector, &aux_ep->aux->ddc);
258 num = drm_add_edid_modes(connector, p->edid);
259
260 pm_runtime_mark_last_busy(panel->dev);
261 pm_runtime_put_autosuspend(panel->dev);
262
263 return num;
264 }
265
266 static const struct drm_panel_funcs atana33xc20_funcs = {
267 .disable = atana33xc20_disable,
268 .enable = atana33xc20_enable,
269 .unprepare = atana33xc20_unprepare,
270 .prepare = atana33xc20_prepare,
271 .get_modes = atana33xc20_get_modes,
272 };
273
atana33xc20_runtime_disable(void * data)274 static void atana33xc20_runtime_disable(void *data)
275 {
276 pm_runtime_disable(data);
277 }
278
atana33xc20_dont_use_autosuspend(void * data)279 static void atana33xc20_dont_use_autosuspend(void *data)
280 {
281 pm_runtime_dont_use_autosuspend(data);
282 }
283
atana33xc20_probe(struct dp_aux_ep_device * aux_ep)284 static int atana33xc20_probe(struct dp_aux_ep_device *aux_ep)
285 {
286 struct atana33xc20_panel *panel;
287 struct device *dev = &aux_ep->dev;
288 int ret;
289
290 panel = devm_kzalloc(dev, sizeof(*panel), GFP_KERNEL);
291 if (!panel)
292 return -ENOMEM;
293 dev_set_drvdata(dev, panel);
294
295 panel->aux = aux_ep->aux;
296
297 panel->supply = devm_regulator_get(dev, "power");
298 if (IS_ERR(panel->supply))
299 return dev_err_probe(dev, PTR_ERR(panel->supply),
300 "Failed to get power supply\n");
301
302 panel->el_on3_gpio = devm_gpiod_get(dev, "enable", GPIOD_OUT_LOW);
303 if (IS_ERR(panel->el_on3_gpio))
304 return dev_err_probe(dev, PTR_ERR(panel->el_on3_gpio),
305 "Failed to get enable GPIO\n");
306
307 panel->no_hpd = of_property_read_bool(dev->of_node, "no-hpd");
308 if (!panel->no_hpd) {
309 panel->hpd_gpio = devm_gpiod_get_optional(dev, "hpd", GPIOD_IN);
310 if (IS_ERR(panel->hpd_gpio))
311 return dev_err_probe(dev, PTR_ERR(panel->hpd_gpio),
312 "Failed to get HPD GPIO\n");
313 }
314
315 pm_runtime_enable(dev);
316 ret = devm_add_action_or_reset(dev, atana33xc20_runtime_disable, dev);
317 if (ret)
318 return ret;
319 pm_runtime_set_autosuspend_delay(dev, 2000);
320 pm_runtime_use_autosuspend(dev);
321 ret = devm_add_action_or_reset(dev, atana33xc20_dont_use_autosuspend, dev);
322 if (ret)
323 return ret;
324
325 drm_panel_init(&panel->base, dev, &atana33xc20_funcs, DRM_MODE_CONNECTOR_eDP);
326
327 pm_runtime_get_sync(dev);
328 ret = drm_panel_dp_aux_backlight(&panel->base, aux_ep->aux);
329 pm_runtime_mark_last_busy(dev);
330 pm_runtime_put_autosuspend(dev);
331 if (ret)
332 return dev_err_probe(dev, ret,
333 "failed to register dp aux backlight\n");
334
335 drm_panel_add(&panel->base);
336
337 return 0;
338 }
339
atana33xc20_remove(struct dp_aux_ep_device * aux_ep)340 static void atana33xc20_remove(struct dp_aux_ep_device *aux_ep)
341 {
342 struct device *dev = &aux_ep->dev;
343 struct atana33xc20_panel *panel = dev_get_drvdata(dev);
344
345 drm_panel_remove(&panel->base);
346 drm_panel_disable(&panel->base);
347 drm_panel_unprepare(&panel->base);
348
349 kfree(panel->edid);
350 }
351
atana33xc20_shutdown(struct dp_aux_ep_device * aux_ep)352 static void atana33xc20_shutdown(struct dp_aux_ep_device *aux_ep)
353 {
354 struct device *dev = &aux_ep->dev;
355 struct atana33xc20_panel *panel = dev_get_drvdata(dev);
356
357 drm_panel_disable(&panel->base);
358 drm_panel_unprepare(&panel->base);
359 }
360
361 static const struct of_device_id atana33xc20_dt_match[] = {
362 { .compatible = "samsung,atna33xc20", },
363 { /* sentinal */ }
364 };
365 MODULE_DEVICE_TABLE(of, atana33xc20_dt_match);
366
367 static const struct dev_pm_ops atana33xc20_pm_ops = {
368 SET_RUNTIME_PM_OPS(atana33xc20_suspend, atana33xc20_resume, NULL)
369 SET_SYSTEM_SLEEP_PM_OPS(pm_runtime_force_suspend,
370 pm_runtime_force_resume)
371 };
372
373 static struct dp_aux_ep_driver atana33xc20_driver = {
374 .driver = {
375 .name = "samsung_atana33xc20",
376 .of_match_table = atana33xc20_dt_match,
377 .pm = &atana33xc20_pm_ops,
378 },
379 .probe = atana33xc20_probe,
380 .remove = atana33xc20_remove,
381 .shutdown = atana33xc20_shutdown,
382 };
383
atana33xc20_init(void)384 static int __init atana33xc20_init(void)
385 {
386 return dp_aux_dp_driver_register(&atana33xc20_driver);
387 }
388 module_init(atana33xc20_init);
389
atana33xc20_exit(void)390 static void __exit atana33xc20_exit(void)
391 {
392 dp_aux_dp_driver_unregister(&atana33xc20_driver);
393 }
394 module_exit(atana33xc20_exit);
395
396 MODULE_DESCRIPTION("Samsung ATANA33XC20 Panel Driver");
397 MODULE_LICENSE("GPL v2");
398