--- /dev/null
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright 2021 Google Inc.
+ *
+ * Panel driver for the Samsung ATNA33XC20 panel. This panel can't be handled
+ * by the DRM_PANEL_SIMPLE driver because its power sequencing is non-standard.
+ */
+
+#include <linux/backlight.h>
+#include <linux/delay.h>
+#include <linux/gpio/consumer.h>
+#include <linux/iopoll.h>
+#include <linux/module.h>
+#include <linux/pm_runtime.h>
+#include <linux/regulator/consumer.h>
+
+#include <drm/drm_dp_aux_bus.h>
+#include <drm/drm_dp_helper.h>
+#include <drm/drm_edid.h>
+#include <drm/drm_panel.h>
+
+struct atana33xc20_panel {
+ struct drm_panel base;
+ bool prepared;
+ bool enabled;
+ bool el3_was_on;
+
+ bool no_hpd;
+ struct gpio_desc *hpd_gpio;
+
+ struct regulator *supply;
+ struct gpio_desc *el_on3_gpio;
+
+ struct edid *edid;
+
+ ktime_t powered_off_time;
+ ktime_t powered_on_time;
+ ktime_t el_on3_off_time;
+};
+
+static inline struct atana33xc20_panel *to_atana33xc20(struct drm_panel *panel)
+{
+ return container_of(panel, struct atana33xc20_panel, base);
+}
+
+static void atana33xc20_wait(ktime_t start_ktime, unsigned int min_ms)
+{
+ ktime_t now_ktime, min_ktime;
+
+ min_ktime = ktime_add(start_ktime, ms_to_ktime(min_ms));
+ now_ktime = ktime_get();
+
+ if (ktime_before(now_ktime, min_ktime))
+ msleep(ktime_to_ms(ktime_sub(min_ktime, now_ktime)) + 1);
+}
+
+static int atana33xc20_suspend(struct device *dev)
+{
+ struct atana33xc20_panel *p = dev_get_drvdata(dev);
+ int ret;
+
+ /*
+ * Note 3 (Example of power off sequence in detail) in spec
+ * specifies to wait 150 ms after deasserting EL3_ON before
+ * powering off.
+ */
+ if (p->el3_was_on)
+ atana33xc20_wait(p->el_on3_off_time, 150);
+
+ ret = regulator_disable(p->supply);
+ if (ret)
+ return ret;
+ p->powered_off_time = ktime_get();
+ p->el3_was_on = false;
+
+ return 0;
+}
+
+static int atana33xc20_resume(struct device *dev)
+{
+ struct atana33xc20_panel *p = dev_get_drvdata(dev);
+ bool hpd_asserted = false;
+ int ret;
+
+ /* T12 (Power off time) is min 500 ms */
+ atana33xc20_wait(p->powered_off_time, 500);
+
+ ret = regulator_enable(p->supply);
+ if (ret)
+ return ret;
+ p->powered_on_time = ktime_get();
+
+ /*
+ * Handle HPD. Note: if HPD is hooked up to a dedicated pin on the
+ * eDP controller then "no_hpd" will be false _and_ "hpd_gpio" will be
+ * NULL. It's up to the controller driver to wait for HPD after
+ * preparing the panel in that case.
+ */
+ if (p->no_hpd) {
+ /* T3 VCC to HPD high is max 200 ms */
+ msleep(200);
+ } else if (p->hpd_gpio) {
+ ret = readx_poll_timeout(gpiod_get_value_cansleep, p->hpd_gpio,
+ hpd_asserted, hpd_asserted,
+ 1000, 200000);
+ if (!hpd_asserted)
+ dev_warn(dev, "Timeout waiting for HPD\n");
+ }
+
+ return 0;
+}
+
+static int atana33xc20_disable(struct drm_panel *panel)
+{
+ struct atana33xc20_panel *p = to_atana33xc20(panel);
+
+ /* Disabling when already disabled is a no-op */
+ if (!p->enabled)
+ return 0;
+
+ gpiod_set_value_cansleep(p->el_on3_gpio, 0);
+ p->el_on3_off_time = ktime_get();
+ p->enabled = false;
+
+ /*
+ * Keep track of the fact that EL_ON3 was on but we haven't power
+ * cycled yet. This lets us know that "el_on3_off_time" is recent (we
+ * don't need to worry about ktime wraparounds) and also makes it
+ * obvious if we try to enable again without a power cycle (see the
+ * warning in atana33xc20_enable()).
+ */
+ p->el3_was_on = true;
+
+ /*
+ * Sleeping 20 ms here (after setting the GPIO) avoids a glitch when
+ * powering off.
+ */
+ msleep(20);
+
+ return 0;
+}
+
+static int atana33xc20_enable(struct drm_panel *panel)
+{
+ struct atana33xc20_panel *p = to_atana33xc20(panel);
+
+ /* Enabling when already enabled is a no-op */
+ if (p->enabled)
+ return 0;
+
+ /*
+ * Once EL_ON3 drops we absolutely need a power cycle before the next
+ * enable or the backlight will never come on again. The code ensures
+ * this because disable() is _always_ followed by unprepare() and
+ * unprepare() forces a suspend with pm_runtime_put_sync_suspend(),
+ * but let's track just to make sure since the requirement is so
+ * non-obvious.
+ */
+ if (WARN_ON(p->el3_was_on))
+ return -EIO;
+
+ /*
+ * Note 2 (Example of power on sequence in detail) in spec specifies
+ * to wait 400 ms after powering on before asserting EL3_on.
+ */
+ atana33xc20_wait(p->powered_on_time, 400);
+
+ gpiod_set_value_cansleep(p->el_on3_gpio, 1);
+ p->enabled = true;
+
+ return 0;
+}
+
+static int atana33xc20_unprepare(struct drm_panel *panel)
+{
+ struct atana33xc20_panel *p = to_atana33xc20(panel);
+ int ret;
+
+ /* Unpreparing when already unprepared is a no-op */
+ if (!p->prepared)
+ return 0;
+
+ /*
+ * Purposely do a put_sync, don't use autosuspend. The panel's tcon
+ * seems to sometimes crash when you stop giving it data and this is
+ * the best way to ensure it will come back.
+ *
+ * NOTE: we still want autosuspend for cases where we only turn on
+ * to get the EDID or otherwise send DP AUX commands to the panel.
+ */
+ ret = pm_runtime_put_sync_suspend(panel->dev);
+ if (ret < 0)
+ return ret;
+ p->prepared = false;
+
+ return 0;
+}
+
+static int atana33xc20_prepare(struct drm_panel *panel)
+{
+ struct atana33xc20_panel *p = to_atana33xc20(panel);
+ int ret;
+
+ /* Preparing when already prepared is a no-op */
+ if (p->prepared)
+ return 0;
+
+ ret = pm_runtime_get_sync(panel->dev);
+ if (ret < 0) {
+ pm_runtime_put_autosuspend(panel->dev);
+ return ret;
+ }
+ p->prepared = true;
+
+ return 0;
+}
+
+static int atana33xc20_get_modes(struct drm_panel *panel,
+ struct drm_connector *connector)
+{
+ struct atana33xc20_panel *p = to_atana33xc20(panel);
+ struct dp_aux_ep_device *aux_ep = to_dp_aux_ep_dev(panel->dev);
+ int num = 0;
+
+ pm_runtime_get_sync(panel->dev);
+
+ if (!p->edid)
+ p->edid = drm_get_edid(connector, &aux_ep->aux->ddc);
+ num = drm_add_edid_modes(connector, p->edid);
+
+ pm_runtime_mark_last_busy(panel->dev);
+ pm_runtime_put_autosuspend(panel->dev);
+
+ return num;
+}
+
+static const struct drm_panel_funcs atana33xc20_funcs = {
+ .disable = atana33xc20_disable,
+ .enable = atana33xc20_enable,
+ .unprepare = atana33xc20_unprepare,
+ .prepare = atana33xc20_prepare,
+ .get_modes = atana33xc20_get_modes,
+};
+
+static void atana33xc20_runtime_disable(void *data)
+{
+ pm_runtime_disable(data);
+}
+
+static void atana33xc20_dont_use_autosuspend(void *data)
+{
+ pm_runtime_dont_use_autosuspend(data);
+}
+
+static int atana33xc20_probe(struct dp_aux_ep_device *aux_ep)
+{
+ struct atana33xc20_panel *panel;
+ struct device *dev = &aux_ep->dev;
+ int ret;
+
+ panel = devm_kzalloc(dev, sizeof(*panel), GFP_KERNEL);
+ if (!panel)
+ return -ENOMEM;
+ dev_set_drvdata(dev, panel);
+
+ panel->supply = devm_regulator_get(dev, "power");
+ if (IS_ERR(panel->supply))
+ return dev_err_probe(dev, PTR_ERR(panel->supply),
+ "Failed to get power supply\n");
+
+ panel->el_on3_gpio = devm_gpiod_get(dev, "enable", GPIOD_OUT_LOW);
+ if (IS_ERR(panel->el_on3_gpio))
+ return dev_err_probe(dev, PTR_ERR(panel->el_on3_gpio),
+ "Failed to get enable GPIO\n");
+
+ panel->no_hpd = of_property_read_bool(dev->of_node, "no-hpd");
+ if (!panel->no_hpd) {
+ panel->hpd_gpio = devm_gpiod_get_optional(dev, "hpd", GPIOD_IN);
+ if (IS_ERR(panel->hpd_gpio))
+ return dev_err_probe(dev, PTR_ERR(panel->hpd_gpio),
+ "Failed to get HPD GPIO\n");
+ }
+
+ pm_runtime_enable(dev);
+ ret = devm_add_action_or_reset(dev, atana33xc20_runtime_disable, dev);
+ if (ret)
+ return ret;
+ pm_runtime_set_autosuspend_delay(dev, 1000);
+ pm_runtime_use_autosuspend(dev);
+ ret = devm_add_action_or_reset(dev, atana33xc20_dont_use_autosuspend, dev);
+ if (ret)
+ return ret;
+
+ drm_panel_init(&panel->base, dev, &atana33xc20_funcs, DRM_MODE_CONNECTOR_eDP);
+
+ pm_runtime_get_sync(dev);
+ ret = drm_panel_dp_aux_backlight(&panel->base, aux_ep->aux);
+ pm_runtime_mark_last_busy(dev);
+ pm_runtime_put_autosuspend(dev);
+ if (ret)
+ return dev_err_probe(dev, ret,
+ "failed to register dp aux backlight\n");
+
+ drm_panel_add(&panel->base);
+
+ return 0;
+}
+
+static void atana33xc20_remove(struct dp_aux_ep_device *aux_ep)
+{
+ struct device *dev = &aux_ep->dev;
+ struct atana33xc20_panel *panel = dev_get_drvdata(dev);
+
+ drm_panel_remove(&panel->base);
+ drm_panel_disable(&panel->base);
+ drm_panel_unprepare(&panel->base);
+
+ kfree(panel->edid);
+}
+
+static void atana33xc20_shutdown(struct dp_aux_ep_device *aux_ep)
+{
+ struct device *dev = &aux_ep->dev;
+ struct atana33xc20_panel *panel = dev_get_drvdata(dev);
+
+ drm_panel_disable(&panel->base);
+ drm_panel_unprepare(&panel->base);
+}
+
+static const struct of_device_id atana33xc20_dt_match[] = {
+ { .compatible = "samsung,atna33xc20", },
+ { /* sentinal */ }
+};
+MODULE_DEVICE_TABLE(of, atana33xc20_dt_match);
+
+static const struct dev_pm_ops atana33xc20_pm_ops = {
+ SET_RUNTIME_PM_OPS(atana33xc20_suspend, atana33xc20_resume, NULL)
+ SET_SYSTEM_SLEEP_PM_OPS(pm_runtime_force_suspend,
+ pm_runtime_force_resume)
+};
+
+static struct dp_aux_ep_driver atana33xc20_driver = {
+ .driver = {
+ .name = "samsung_atana33xc20",
+ .of_match_table = atana33xc20_dt_match,
+ .pm = &atana33xc20_pm_ops,
+ },
+ .probe = atana33xc20_probe,
+ .remove = atana33xc20_remove,
+ .shutdown = atana33xc20_shutdown,
+};
+
+static int __init atana33xc20_init(void)
+{
+ return dp_aux_dp_driver_register(&atana33xc20_driver);
+}
+module_init(atana33xc20_init);
+
+static void __exit atana33xc20_exit(void)
+{
+ dp_aux_dp_driver_unregister(&atana33xc20_driver);
+}
+module_exit(atana33xc20_exit);
+
+MODULE_DESCRIPTION("Samsung ATANA33XC20 Panel Driver");
+MODULE_LICENSE("GPL v2");
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