gpu: drm: adp: Add a backlight driver for the Summit LCD

This is the display panel used for the touchbar on laptops that have it.

Signed-off-by: Sasha Finkelstein <fnkl.kernel@gmail.com>

Author: WhatAmISupposedToPutHere

drivers/gpu/drm/adp/panel-summit.c

@@ -0,0 +1,104 @@
+// SPDX-License-Identifier: GPL-2.0-only
+
+#include <linux/backlight.h>
+#include <drm/drm_mipi_dsi.h>
+#include <video/mipi_display.h>
+
+struct summit_data {
+	struct mipi_dsi_device *dsi;
+	struct backlight_device *bl;
+};
+
+static int summit_set_brightness(struct device *dev)
+{
+	struct summit_data *panel = dev_get_drvdata(dev);
+	int level = backlight_get_brightness(panel->bl);
+	ssize_t err = mipi_dsi_dcs_write(panel->dsi, MIPI_DCS_SET_DISPLAY_BRIGHTNESS,
+					 &level, 1);
+	if (err < 0)
+		return err;
+	return 0;
+}
+
+static int summit_bl_update_status(struct backlight_device *dev)
+{
+	return summit_set_brightness(&dev->dev);
+}
+
+static int summit_bl_get_brightness(struct backlight_device *dev)
+{
+	return backlight_get_brightness(dev);
+}
+
+static const struct backlight_ops summit_bl_ops = {
+	.get_brightness = summit_bl_get_brightness,
+	.update_status	= summit_bl_update_status,
+};
+
+static int summit_probe(struct mipi_dsi_device *dsi)
+{
+	struct backlight_properties props = { 0 };
+	struct device *dev = &dsi->dev;
+	struct summit_data *panel;
+	panel = devm_kzalloc(dev, sizeof(*panel), GFP_KERNEL);
+	if (!panel)
+		return -ENOMEM;
+
+	mipi_dsi_set_drvdata(dsi, panel);
+	panel->dsi = dsi;
+	props.max_brightness = 255;
+	props.type = BACKLIGHT_RAW;
+
+	panel->bl = devm_backlight_device_register(dev, dev_name(dev),
+						   dev, panel, &summit_bl_ops, &props);
+	if (IS_ERR(panel->bl)) {
+		return PTR_ERR(panel->bl);
+	}
+
+	return mipi_dsi_attach(dsi);
+}
+
+static void summit_remove(struct mipi_dsi_device *dsi)
+{
+	mipi_dsi_detach(dsi);
+}
+
+static int summit_resume(struct device *dev)
+{
+	return summit_set_brightness(dev);
+}
+
+static int summit_suspend(struct device *dev)
+{
+	int level = 0;
+	struct summit_data *panel = dev_get_drvdata(dev);
+	ssize_t err = mipi_dsi_dcs_write(panel->dsi, MIPI_DCS_SET_DISPLAY_BRIGHTNESS,
+					 &level, 1);
+	if (err < 0)
+		return err;
+	return 0;
+}
+
+static DEFINE_SIMPLE_DEV_PM_OPS(summit_pm_ops, summit_suspend,
+				summit_resume);
+
+static const struct of_device_id summit_of_match[] = {
+	{ .compatible = "apple,summit" },
+	{},
+};
+
+MODULE_DEVICE_TABLE(of, summit_of_match);
+
+static struct mipi_dsi_driver summit_driver = {
+	.probe = summit_probe,
+	.remove = summit_remove,
+	.driver = {
+		.name = "panel-summit",
+		.of_match_table = summit_of_match,
+		.pm = pm_sleep_ptr(&summit_pm_ops),
+	},
+};
+module_mipi_dsi_driver(summit_driver);
+
+MODULE_DESCRIPTION("Summit Display Panel Driver");
+MODULE_LICENSE("GPL");