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

Eric Anholt
2017-05-11T23:56:40Z

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