From 4da2b00d471f7fca0d770551afafa95e85ec9b89 Mon Sep 17 00:00:00 2001
From: Eric Anholt <eric@anholt.net>
Date: Tue, 26 Apr 2016 13:46:13 -0700
Subject: [PATCH] drm/panel: Add support for the Raspberry Pi 7" Touchscreen.

Signed-off-by: Eric Anholt <eric@anholt.net>
---
 drivers/gpu/drm/panel/Kconfig                      |   9 +
 drivers/gpu/drm/panel/Makefile                     |   1 +
 .../gpu/drm/panel/panel-raspberrypi-touchscreen.c  | 347 +++++++++++++++++++++
 3 files changed, 357 insertions(+)
 create mode 100644 drivers/gpu/drm/panel/panel-raspberrypi-touchscreen.c

--- a/drivers/gpu/drm/panel/Kconfig
+++ b/drivers/gpu/drm/panel/Kconfig
@@ -31,6 +31,15 @@ config DRM_PANEL_LG_LG4573
 	  Say Y here if you want to enable support for LG4573 RGB panel.
 	  To compile this driver as a module, choose M here.
 
+config DRM_PANEL_RASPBERRYPI_TOUCHSCREEN
+	tristate "Raspberry Pi 7-inch touchscreen panel"
+	depends on DRM_MIPI_DSI
+	depends on BACKLIGHT_CLASS_DEVICE
+	help
+	  Say Y here if you want to enable support for the Raspberry
+	  Pi 7" Touchscreen.  To compile this driver as a module,
+	  choose M here.
+
 config DRM_PANEL_SAMSUNG_S6E8AA0
 	tristate "Samsung S6E8AA0 DSI video mode panel"
 	depends on OF
--- a/drivers/gpu/drm/panel/Makefile
+++ b/drivers/gpu/drm/panel/Makefile
@@ -1,5 +1,6 @@
 obj-$(CONFIG_DRM_PANEL_SIMPLE) += panel-simple.o
 obj-$(CONFIG_DRM_PANEL_LG_LG4573) += panel-lg-lg4573.o
+obj-$(CONFIG_DRM_PANEL_RASPBERRYPI_TOUCHSCREEN) += panel-raspberrypi-touchscreen.o
 obj-$(CONFIG_DRM_PANEL_SAMSUNG_LD9040) += panel-samsung-ld9040.o
 obj-$(CONFIG_DRM_PANEL_SAMSUNG_S6E8AA0) += panel-samsung-s6e8aa0.o
 obj-$(CONFIG_DRM_PANEL_SHARP_LQ101R1SX01) += panel-sharp-lq101r1sx01.o
--- /dev/null
+++ b/drivers/gpu/drm/panel/panel-raspberrypi-touchscreen.c
@@ -0,0 +1,347 @@
+/*
+ * Copyright © 2016 Broadcom Limited
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * Portions of this file (derived from panel-simple.c) are:
+ *
+ * Copyright (C) 2013, NVIDIA Corporation.  All rights reserved.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sub license,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the
+ * next paragraph) shall be included in all copies or substantial portions
+ * of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+ * DEALINGS IN THE SOFTWARE.
+ */
+
+/**
+ * DOC: Raspberry Pi 7" touchscreen panel driver.
+ *
+ * The 7" touchscreen consists of a DPI LCD panel, a Toshiba
+ * TC358762XBG DSI-DPI bridge, and an I2C-connected Atmel ATTINY88-MUR
+ * controlling power management, the LCD PWM, and the touchscreen.
+ *
+ * This driver presents this device as a MIPI DSI panel to the DRM
+ * driver, and should expose the touchscreen as a HID device.
+ */
+
+#include <linux/backlight.h>
+#include <linux/delay.h>
+#include <linux/err.h>
+#include <linux/fb.h>
+#include <linux/gpio.h>
+#include <linux/gpio/consumer.h>
+#include <linux/i2c.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_device.h>
+#include <linux/of_graph.h>
+#include <linux/pm.h>
+
+#include <drm/drm_panel.h>
+#include <drm/drmP.h>
+#include <drm/drm_crtc.h>
+#include <drm/drm_mipi_dsi.h>
+#include <drm/drm_panel.h>
+
+struct rpi_touchscreen {
+	struct drm_panel base;
+	struct mipi_dsi_device *dsi;
+	struct i2c_client *bridge_i2c;
+	struct backlight_device *backlight;
+
+	bool prepared;
+	bool enabled;
+
+	/* Version of the firmware on the bridge chip */
+	int atmel_ver;
+};
+
+static const struct drm_display_mode rpi_touchscreen_modes[] = {
+	{
+		/* This is assuming that we'll be running the DSI PLL
+		 * at 2Ghz / 3 (since we only get integer dividers),
+		 * so a pixel clock of 2Ghz / 3 / 8.
+		 */
+		.clock = 83333,
+		.hdisplay = 800,
+		.hsync_start = 800 + 61,
+		.hsync_end = 800 + 61 + 2,
+		.htotal = 800 + 61 + 2 + 44,
+		.vdisplay = 480,
+		.vsync_start = 480 + 7,
+		.vsync_end = 480 + 7 + 2,
+		.vtotal = 480 + 7 + 2 + 21,
+		.vrefresh = 60,
+	},
+};
+
+static struct rpi_touchscreen *panel_to_ts(struct drm_panel *panel)
+{
+	return container_of(panel, struct rpi_touchscreen, base);
+}
+
+struct regdump {
+	const char *reg;
+	u32 offset;
+};
+
+#define REGDUMP(reg) { #reg, reg }
+
+static int rpi_touchscreen_disable(struct drm_panel *panel)
+{
+	struct rpi_touchscreen *ts = panel_to_ts(panel);
+	pr_err("disable\n");
+
+	if (!ts->enabled)
+		return 0;
+
+	if (ts->backlight) {
+		ts->backlight->props.power = FB_BLANK_POWERDOWN;
+		backlight_update_status(ts->backlight);
+	}
+
+	ts->enabled = false;
+
+	return 0;
+}
+
+static int rpi_touchscreen_unprepare(struct drm_panel *panel)
+{
+	struct rpi_touchscreen *ts = panel_to_ts(panel);
+
+	if (!ts->prepared)
+		return 0;
+
+	ts->prepared = false;
+
+	return 0;
+}
+
+static int rpi_touchscreen_prepare(struct drm_panel *panel)
+{
+	struct rpi_touchscreen *ts = panel_to_ts(panel);
+
+	if (ts->prepared)
+		return 0;
+
+	ts->prepared = true;
+
+	return 0;
+}
+
+/*
+ * Powers on the panel once the DSI link is up.
+ *
+ * The TC358762 is run in PLLOFF mode, where it usees the MIPI DSI
+ * byte clock instead of an external reference clock.  This means that
+ * we need the DSI host to be on and transmitting before we start
+ * talking to it.
+ */
+static int rpi_touchscreen_enable(struct drm_panel *panel)
+{
+	struct rpi_touchscreen *ts = panel_to_ts(panel);
+
+	if (ts->enabled)
+		return 0;
+
+	if (ts->backlight) {
+		ts->backlight->props.power = FB_BLANK_UNBLANK;
+		backlight_update_status(ts->backlight);
+	}
+
+	ts->enabled = true;
+
+	return 0;
+}
+
+static int rpi_touchscreen_get_modes(struct drm_panel *panel)
+{
+	struct drm_connector *connector = panel->connector;
+	struct drm_device *drm = panel->drm;
+	unsigned int i, num = 0;
+
+	for (i = 0; i < ARRAY_SIZE(rpi_touchscreen_modes); i++) {
+		const struct drm_display_mode *m = &rpi_touchscreen_modes[i];
+		struct drm_display_mode *mode;
+
+		mode = drm_mode_duplicate(drm, m);
+		if (!mode) {
+			dev_err(drm->dev, "failed to add mode %ux%u@%u\n",
+				m->hdisplay, m->vdisplay, m->vrefresh);
+			continue;
+		}
+
+		mode->type |= DRM_MODE_TYPE_DRIVER;
+
+		if (i == 0)
+			mode->type |= DRM_MODE_TYPE_PREFERRED;
+
+		drm_mode_set_name(mode);
+
+		drm_mode_probed_add(connector, mode);
+		num++;
+	}
+
+	connector->display_info.bpc = 8;
+	connector->display_info.width_mm = 217; /* XXX */
+	connector->display_info.height_mm = 136; /* XXX */
+
+	return num;
+}
+
+static int rpi_touchscreen_backlight_update(struct backlight_device *bl)
+{
+	int brightness = bl->props.brightness;
+
+	if (bl->props.power != FB_BLANK_UNBLANK ||
+	    bl->props.state & (BL_CORE_SUSPENDED | BL_CORE_FBBLANK))
+		brightness = 0;
+
+	return 0;
+}
+
+static const struct backlight_ops rpi_touchscreen_backlight_ops = {
+	.update_status	= rpi_touchscreen_backlight_update,
+};
+
+static const struct drm_panel_funcs rpi_touchscreen_funcs = {
+	.disable = rpi_touchscreen_disable,
+	.unprepare = rpi_touchscreen_unprepare,
+	.prepare = rpi_touchscreen_prepare,
+	.enable = rpi_touchscreen_enable,
+	.get_modes = rpi_touchscreen_get_modes,
+};
+
+static struct i2c_client *rpi_touchscreen_get_i2c(struct device *dev,
+						  const char *name)
+{
+	struct device_node *node;
+	struct i2c_client *client;
+
+	node = of_parse_phandle(dev->of_node, name, 0);
+	if (!node)
+		return ERR_PTR(-ENODEV);
+
+	client = of_find_i2c_device_by_node(node);
+
+	of_node_put(node);
+
+	return client;
+}
+
+static int rpi_touchscreen_dsi_probe(struct mipi_dsi_device *dsi)
+{
+	struct device *dev = &dsi->dev;
+	struct rpi_touchscreen *ts;
+	int ret;
+
+	ts = devm_kzalloc(dev, sizeof(*ts), GFP_KERNEL);
+	if (!ts)
+		return -ENOMEM;
+
+	dev_set_drvdata(dev, ts);
+
+	ts->dsi = dsi;
+	dsi->mode_flags = (MIPI_DSI_MODE_VIDEO |
+			   MIPI_DSI_MODE_VIDEO_SYNC_PULSE);
+	dsi->format = MIPI_DSI_FMT_RGB888;
+	dsi->lanes = 1;
+
+	ts->bridge_i2c =
+		rpi_touchscreen_get_i2c(dev, "raspberrypi,touchscreen-bridge");
+	if (!ts->bridge_i2c) {
+		ret = -EPROBE_DEFER;
+		return ret;
+	}
+
+#if 0
+	ts->backlight =
+		devm_backlight_device_register(dev,
+					       "raspberrypi-touchscreen-backlight",
+					       dev, ts,
+					       &rpi_touchscreen_backlight_ops,
+					       NULL);
+	if (IS_ERR(ts->backlight)) {
+		DRM_ERROR("failed to register backlight\n");
+		return PTR_ERR(ts->backlight);
+	}
+	ts->backlight->props.max_brightness = RPI_TOUCHSCREEN_MAX_BRIGHTNESS;
+	ts->backlight->props.brightness = RPI_TOUCHSCREEN_MAX_BRIGHTNESS;
+#endif
+
+	drm_panel_init(&ts->base);
+	ts->base.dev = dev;
+	ts->base.funcs = &rpi_touchscreen_funcs;
+
+	ret = drm_panel_add(&ts->base);
+	if (ret < 0)
+		goto err_release_bridge;
+
+	return mipi_dsi_attach(dsi);
+
+err_release_bridge:
+	put_device(&ts->bridge_i2c->dev);
+	return ret;
+}
+
+static int rpi_touchscreen_dsi_remove(struct mipi_dsi_device *dsi)
+{
+	struct device *dev = &dsi->dev;
+	struct rpi_touchscreen *ts = dev_get_drvdata(dev);
+	int ret;
+
+	ret = mipi_dsi_detach(dsi);
+	if (ret < 0) {
+		dev_err(&dsi->dev, "failed to detach from DSI host: %d\n", ret);
+		return ret;
+	}
+
+	drm_panel_detach(&ts->base);
+	drm_panel_remove(&ts->base);
+
+	put_device(&ts->bridge_i2c->dev);
+
+	return 0;
+}
+
+static void rpi_touchscreen_dsi_shutdown(struct mipi_dsi_device *dsi)
+{
+	/* XXX: poweroff */
+}
+
+static const struct of_device_id rpi_touchscreen_of_match[] = {
+	{ .compatible = "raspberrypi,touchscreen" },
+	{ } /* sentinel */
+};
+MODULE_DEVICE_TABLE(of, rpi_touchscreen_of_match);
+
+static struct mipi_dsi_driver rpi_touchscreen_driver = {
+	.driver = {
+		.name = "raspberrypi-touchscreen",
+		.of_match_table = rpi_touchscreen_of_match,
+	},
+	.probe = rpi_touchscreen_dsi_probe,
+	.remove = rpi_touchscreen_dsi_remove,
+	.shutdown = rpi_touchscreen_dsi_shutdown,
+};
+module_mipi_dsi_driver(rpi_touchscreen_driver);
+
+MODULE_AUTHOR("Eric Anholt <eric@anholt.net>");
+MODULE_DESCRIPTION("Raspberry Pi 7-inch touchscreen driver");
+MODULE_LICENSE("GPL v2");
