[PATCH 3/4] drm/bridge: Add support for the Raspberry Pi 7" Touchscreen.

[Eric Anholt <eric@anholt.net>]

This driver communicates with the Atmel microcontroller for sequencing
the poweron of the TC358762 DSI-DPI bridge and controlling the
backlight PWM.

The following lines are required in config.txt, to keep the firmware
from trying to bash our I2C lines and steal the DSI interrupts:

    disable_touchscreen=1
    ignore_lcd=2
    mask_gpu_interrupt1=0x1000

This means that the firmware won't power on the panel at boot time (no
rainbow) and the touchscreen input won't work.  A native input driver
for the touchscreen still needs to be written.

Signed-off-by: Eric Anholt <eric@anholt.net>
---
 drivers/gpu/drm/bridge/Kconfig                   |   9 +
 drivers/gpu/drm/bridge/Makefile                  |   1 +
 drivers/gpu/drm/bridge/raspberrypi-touchscreen.c | 460 +++++++++++++++++++++++
 3 files changed, 470 insertions(+)
 create mode 100644 drivers/gpu/drm/bridge/raspberrypi-touchscreen.c

diff --git a/drivers/gpu/drm/bridge/Kconfig b/drivers/gpu/drm/bridge/Kconfig
index c4daca38743c..9adda62f45df 100644
--- a/drivers/gpu/drm/bridge/Kconfig
+++ b/drivers/gpu/drm/bridge/Kconfig
@@ -76,6 +76,15 @@ config DRM_SIL_SII8620
 	help
 	  Silicon Image SII8620 HDMI/MHL bridge chip driver.
 
+config DRM_RASPBERRYPI_TOUCHSCREEN_BRIDGE
+	tristate "Raspberry Pi 7-inch touchscreen bridge"
+	depends on OF
+	select DRM_KMS_HELPER
+	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_SII902X
 	tristate "Silicon Image sii902x RGB/HDMI bridge"
 	depends on OF
diff --git a/drivers/gpu/drm/bridge/Makefile b/drivers/gpu/drm/bridge/Makefile
index 3fe2226ee2f2..6226ed41f4d1 100644
--- a/drivers/gpu/drm/bridge/Makefile
+++ b/drivers/gpu/drm/bridge/Makefile
@@ -6,6 +6,7 @@ obj-$(CONFIG_DRM_LVDS_ENCODER) += lvds-encoder.o
 obj-$(CONFIG_DRM_MEGACHIPS_STDPXXXX_GE_B850V3_FW) += megachips-stdpxxxx-ge-b850v3-fw.o
 obj-$(CONFIG_DRM_NXP_PTN3460) += nxp-ptn3460.o
 obj-$(CONFIG_DRM_PARADE_PS8622) += parade-ps8622.o
+obj-$(CONFIG_DRM_RASPBERRYPI_TOUCHSCREEN_BRIDGE) += raspberrypi-touchscreen.o
 obj-$(CONFIG_DRM_SIL_SII8620) += sil-sii8620.o
 obj-$(CONFIG_DRM_SII902X) += sii902x.o
 obj-$(CONFIG_DRM_TOSHIBA_TC358767) += tc358767.o
diff --git a/drivers/gpu/drm/bridge/raspberrypi-touchscreen.c b/drivers/gpu/drm/bridge/raspberrypi-touchscreen.c
new file mode 100644
index 000000000000..b19b5a83f210
--- /dev/null
+++ b/drivers/gpu/drm/bridge/raspberrypi-touchscreen.c
@@ -0,0 +1,460 @@
+/*
+ * Copyright © 2016-2017 Broadcom
+ *
+ * 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.
+ */
+
+/**
+ * Raspberry Pi 7" touchscreen panel bridge 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 initial register
+ * setup of the Tohsiba.
+ *
+ * This driver controls the TC358762 and ATTINY88, bridging between
+ * the DSI host and the LCD panel.  The panel-simple driver has the
+ * actual panel.
+ */
+
+#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/drmP.h>
+#include <drm/drm_atomic_helper.h>
+#include <drm/drm_crtc.h>
+#include <drm/drm_crtc_helper.h>
+#include <drm/drm_mipi_dsi.h>
+#include <drm/drm_of.h>
+#include <drm/drm_panel.h>
+
+/* I2C registers of the Atmel microcontroller. */
+enum REG_ADDR {
+	REG_ID = 0x80,
+	REG_PORTA, /* BIT(2) for horizontal flip, BIT(3) for vertical flip */
+	REG_PORTB,
+	REG_PORTC,
+	REG_PORTD,
+	REG_POWERON,
+	REG_PWM,
+	REG_DDRA,
+	REG_DDRB,
+	REG_DDRC,
+	REG_DDRD,
+	REG_TEST,
+	REG_WR_ADDRL,
+	REG_WR_ADDRH,
+	REG_READH,
+	REG_READL,
+	REG_WRITEH,
+	REG_WRITEL,
+	REG_ID2,
+};
+
+/* We only turn the PWM on or off, without varying values. */
+#define RPI_TOUCHSCREEN_MAX_BRIGHTNESS 1
+
+/* DSI D-PHY Layer Registers */
+#define D0W_DPHYCONTTX		0x0004
+#define CLW_DPHYCONTRX		0x0020
+#define D0W_DPHYCONTRX		0x0024
+#define D1W_DPHYCONTRX		0x0028
+#define COM_DPHYCONTRX		0x0038
+#define CLW_CNTRL		0x0040
+#define D0W_CNTRL		0x0044
+#define D1W_CNTRL		0x0048
+#define DFTMODE_CNTRL		0x0054
+
+/* DSI PPI Layer Registers */
+#define PPI_STARTPPI		0x0104
+#define PPI_BUSYPPI		0x0108
+#define PPI_LINEINITCNT		0x0110
+#define PPI_LPTXTIMECNT		0x0114
+#define PPI_LANEENABLE		0x0134
+#define PPI_TX_RX_TA		0x013C
+#define PPI_CLS_ATMR		0x0140
+#define PPI_D0S_ATMR		0x0144
+#define PPI_D1S_ATMR		0x0148
+#define PPI_D0S_CLRSIPOCOUNT	0x0164
+#define PPI_D1S_CLRSIPOCOUNT	0x0168
+#define CLS_PRE			0x0180
+#define D0S_PRE			0x0184
+#define D1S_PRE			0x0188
+#define CLS_PREP		0x01A0
+#define D0S_PREP		0x01A4
+#define D1S_PREP		0x01A8
+#define CLS_ZERO		0x01C0
+#define D0S_ZERO		0x01C4
+#define D1S_ZERO		0x01C8
+#define PPI_CLRFLG		0x01E0
+#define PPI_CLRSIPO		0x01E4
+#define HSTIMEOUT		0x01F0
+#define HSTIMEOUTENABLE		0x01F4
+
+/* DSI Protocol Layer Registers */
+#define DSI_STARTDSI		0x0204
+#define DSI_BUSYDSI		0x0208
+#define DSI_LANEENABLE		0x0210
+# define DSI_LANEENABLE_CLOCK		BIT(0)
+# define DSI_LANEENABLE_D0		BIT(1)
+# define DSI_LANEENABLE_D1		BIT(2)
+
+#define DSI_LANESTATUS0		0x0214
+#define DSI_LANESTATUS1		0x0218
+#define DSI_INTSTATUS		0x0220
+#define DSI_INTMASK		0x0224
+#define DSI_INTCLR		0x0228
+#define DSI_LPTXTO		0x0230
+#define DSI_MODE		0x0260
+#define DSI_PAYLOAD0		0x0268
+#define DSI_PAYLOAD1		0x026C
+#define DSI_SHORTPKTDAT		0x0270
+#define DSI_SHORTPKTREQ		0x0274
+#define DSI_BTASTA		0x0278
+#define DSI_BTACLR		0x027C
+
+/* DSI General Registers */
+#define DSIERRCNT		0x0300
+#define DSISIGMOD		0x0304
+
+/* DSI Application Layer Registers */
+#define APLCTRL			0x0400
+#define APLSTAT			0x0404
+#define APLERR			0x0408
+#define PWRMOD			0x040C
+#define RDPKTLN			0x0410
+#define PXLFMT			0x0414
+#define MEMWRCMD		0x0418
+
+/* LCDC/DPI Host Registers */
+#define LCDCTRL			0x0420
+#define HSR			0x0424
+#define HDISPR			0x0428
+#define VSR			0x042C
+#define VDISPR			0x0430
+#define VFUEN			0x0434
+
+/* DBI-B Host Registers */
+#define DBIBCTRL		0x0440
+
+/* SPI Master Registers */
+#define SPICMR			0x0450
+#define SPITCR			0x0454
+
+/* System Controller Registers */
+#define SYSSTAT			0x0460
+#define SYSCTRL			0x0464
+#define SYSPLL1			0x0468
+#define SYSPLL2			0x046C
+#define SYSPLL3			0x0470
+#define SYSPMCTRL		0x047C
+
+/* GPIO Registers */
+#define GPIOC			0x0480
+#define GPIOO			0x0484
+#define GPIOI			0x0488
+
+/* I2C Registers */
+#define I2CCLKCTRL		0x0490
+
+/* Chip/Rev Registers */
+#define IDREG			0x04A0
+
+/* Debug Registers */
+#define WCMDQUEUE		0x0500
+#define RCMDQUEUE		0x0504
+
+struct rpi_touchscreen {
+	struct drm_bridge base;
+	struct drm_bridge *panel_bridge;
+	struct mipi_dsi_device *dsi;
+	struct i2c_client *bridge_i2c;
+};
+
+static struct rpi_touchscreen *bridge_to_ts(struct drm_bridge *bridge)
+{
+	return container_of(bridge, struct rpi_touchscreen, base);
+}
+
+static u8 rpi_touchscreen_i2c_read(struct rpi_touchscreen *ts, u8 reg)
+{
+	return i2c_smbus_read_byte_data(ts->bridge_i2c, reg);
+}
+
+static void rpi_touchscreen_i2c_write(struct rpi_touchscreen *ts,
+				      u8 reg, u8 val)
+{
+	int ret;
+
+	ret = i2c_smbus_write_byte_data(ts->bridge_i2c, reg, val);
+	if (ret)
+		dev_err(&ts->dsi->dev, "I2C write failed: %d\n", ret);
+}
+
+static int rpi_touchscreen_write(struct rpi_touchscreen *ts, u16 reg, u32 val)
+{
+#if 0
+	/* The firmware uses LP DSI transactions like this to bring up
+	 * the hardware, which should be faster than using I2C to then
+	 * pass to the Toshiba.  However, I was unable to get it to
+	 * work.
+	 */
+	u8 msg[] = {
+		reg,
+		reg >> 8,
+		val,
+		val >> 8,
+		val >> 16,
+		val >> 24,
+	};
+
+	mipi_dsi_dcs_write_buffer(ts->dsi, msg, sizeof(msg));
+#else
+	rpi_touchscreen_i2c_write(ts, REG_WR_ADDRH, reg >> 8);
+	rpi_touchscreen_i2c_write(ts, REG_WR_ADDRL, reg);
+	rpi_touchscreen_i2c_write(ts, REG_WRITEH, val >> 8);
+	rpi_touchscreen_i2c_write(ts, REG_WRITEL, val);
+#endif
+
+	return 0;
+}
+
+static void rpi_bridge_disable(struct drm_bridge *bridge)
+{
+	struct rpi_touchscreen *ts = bridge_to_ts(bridge);
+
+	rpi_touchscreen_i2c_write(ts, REG_PWM, 0);
+
+	rpi_touchscreen_i2c_write(ts, REG_POWERON, 0);
+	udelay(1);
+}
+
+static void rpi_bridge_enable(struct drm_bridge *bridge)
+{
+	struct rpi_touchscreen *ts = bridge_to_ts(bridge);
+	int i;
+
+	rpi_touchscreen_i2c_write(ts, REG_POWERON, 1);
+	/* Wait for nPWRDWN to go low to indicate poweron is done. */
+	for (i = 0; i < 100; i++) {
+		if (rpi_touchscreen_i2c_read(ts, REG_PORTB) & 1)
+			break;
+	}
+
+	rpi_touchscreen_write(ts, DSI_LANEENABLE,
+			      DSI_LANEENABLE_CLOCK |
+			      DSI_LANEENABLE_D0);
+	rpi_touchscreen_write(ts, PPI_D0S_CLRSIPOCOUNT, 0x05);
+	rpi_touchscreen_write(ts, PPI_D1S_CLRSIPOCOUNT, 0x05);
+	rpi_touchscreen_write(ts, PPI_D0S_ATMR, 0x00);
+	rpi_touchscreen_write(ts, PPI_D1S_ATMR, 0x00);
+	rpi_touchscreen_write(ts, PPI_LPTXTIMECNT, 0x03);
+
+	rpi_touchscreen_write(ts, SPICMR, 0x00);
+	rpi_touchscreen_write(ts, LCDCTRL, 0x00100150);
+	rpi_touchscreen_write(ts, SYSCTRL, 0x040f);
+	msleep(100);
+
+	rpi_touchscreen_write(ts, PPI_STARTPPI, 0x01);
+	rpi_touchscreen_write(ts, DSI_STARTDSI, 0x01);
+	msleep(100);
+
+	/* Turn on the backlight. */
+	rpi_touchscreen_i2c_write(ts, REG_PWM, 255);
+
+	/* Default to the same orientation as the closed source
+	 * firmware used for the panel.  Runtime rotation
+	 * configuration will be supported using VC4's plane
+	 * orientation bits.
+	 */
+	rpi_touchscreen_i2c_write(ts, REG_PORTA, BIT(2));
+}
+
+static int rpi_bridge_attach(struct drm_bridge *bridge)
+{
+	struct rpi_touchscreen *ts = bridge_to_ts(bridge);
+
+	return drm_bridge_attach(bridge->encoder, ts->panel_bridge, bridge);
+}
+
+static struct drm_bridge_funcs rpi_bridge_funcs = {
+	.enable = rpi_bridge_enable,
+	.disable = rpi_bridge_disable,
+	.attach = rpi_bridge_attach,
+};
+
+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);
+	if (!client)
+		return ERR_PTR(-ENODEV);
+
+	return client;
+}
+
+static int rpi_touchscreen_dsi_probe(struct mipi_dsi_device *dsi)
+{
+	struct device *dev = &dsi->dev;
+	struct drm_panel *panel;
+	struct rpi_touchscreen *ts;
+	int ret, ver;
+
+	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 |
+			   MIPI_DSI_MODE_LPM);
+	dsi->format = MIPI_DSI_FMT_RGB888;
+	dsi->lanes = 1;
+
+	ts->bridge_i2c =
+		rpi_touchscreen_get_i2c(dev, "raspberrypi,touchscreen-bridge");
+	if (IS_ERR(ts->bridge_i2c)) {
+		ret = -EPROBE_DEFER;
+		return ret;
+	}
+
+	ver = rpi_touchscreen_i2c_read(ts, REG_ID);
+	if (ver < 0) {
+		dev_err(dev, "Atmel I2C read failed: %d\n", ver);
+		return -ENODEV;
+	}
+
+	switch (ver) {
+	case 0xde: /* ver 1 */
+	case 0xc3: /* ver 2 */
+		break;
+	default:
+		dev_err(dev, "Unknown Atmel firmware revision: 0x%02x\n", ver);
+		ret = -ENODEV;
+		goto err_release_i2c;
+	}
+
+	drm_of_find_panel_or_bridge(dev->of_node, 0, 0, &panel, NULL);
+	if (!panel)
+		return -EPROBE_DEFER;
+
+	ts->panel_bridge = drm_panel_bridge_add(panel, DRM_MODE_CONNECTOR_DSI);
+	if (IS_ERR(ts->panel_bridge)) {
+		dev_err(dev, "Failed to create panel bridge\n");
+		ret = PTR_ERR(ts->panel_bridge);
+		goto err_release_i2c;
+	}
+
+	/* Turn off at boot, so we can cleanly sequence powering on. */
+	rpi_touchscreen_i2c_write(ts, REG_POWERON, 0);
+
+	ts->base.funcs = &rpi_bridge_funcs;
+	ts->base.of_node = dev->of_node;
+
+	ret = drm_bridge_add(&ts->base);
+	if (ret) {
+		dev_err(dev, "Failed to add bridge\n");
+		goto err_remove_bridge;
+	}
+
+	return mipi_dsi_attach(dsi);
+
+err_remove_bridge:
+	drm_panel_bridge_remove(ts->panel_bridge);
+err_release_i2c:
+	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_bridge_remove(ts->panel_bridge);
+	drm_bridge_remove(&ts->base);
+
+	put_device(&ts->bridge_i2c->dev);
+
+	return 0;
+}
+
+static void rpi_touchscreen_dsi_shutdown(struct mipi_dsi_device *dsi)
+{
+	struct device *dev = &dsi->dev;
+	struct rpi_touchscreen *ts = dev_get_drvdata(dev);
+
+	rpi_touchscreen_i2c_write(ts, REG_POWERON, 0);
+}
+
+static const struct of_device_id rpi_touchscreen_of_match[] = {
+	{ .compatible = "raspberrypi,7inch-touchscreen-bridge" },
+	{ } /* sentinel */
+};
+MODULE_DEVICE_TABLE(of, rpi_touchscreen_of_match);
+
+static struct mipi_dsi_driver rpi_touchscreen_driver = {
+	.driver = {
+		.name = "raspberrypi-touchscreen-bridge",
+		.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");
-- 
2.11.0