Date:   Fri, 6 Oct 2017 09:38:17 +0530
From:   Archit Taneja <architt@...eaurora.org>
To:     Eric Anholt <eric@...olt.net>, dri-devel@...ts.freedesktop.org,
        Andrzej Hajda <a.hajda@...sung.com>,
        Laurent Pinchart <Laurent.pinchart@...asonboard.com>,
        Thierry Reding <thierry.reding@...il.com>
Cc:     linux-kernel@...r.kernel.org
Subject: Re: [PATCH v6 3/3] drm/panel: Add support for the Raspberry Pi 7"
 Touchscreen.



On 09/28/2017 01:06 AM, Eric Anholt wrote:
> This driver communicates with the Atmel microcontroller for sequencing
> the poweron of the TC358762 DSI-DPI bridge and controlling the
> backlight PWM.
> 
> v2: Set the same default orientation as the closed source firmware
>      used, which is the best for viewing angle.
> v3: Rewrite as an i2c client driver after bridge driver rejection.
> v4: Finish probe without the DSI host, using the new delayed
>      registration, and attach to the host during mipi_dsi_driver probe.
> v5: Rework to drop the "probe without DSI host" mode again, now that
>      vc4 will create the host early on.

Reviewed-by: Archit Taneja <architt@...eaurora.org>

> 
> Signed-off-by: Eric Anholt <eric@...olt.net>
> ---
>   drivers/gpu/drm/panel/Kconfig                      |   8 +
>   drivers/gpu/drm/panel/Makefile                     |   1 +
>   .../gpu/drm/panel/panel-raspberrypi-touchscreen.c  | 517 +++++++++++++++++++++
>   3 files changed, 526 insertions(+)
>   create mode 100644 drivers/gpu/drm/panel/panel-raspberrypi-touchscreen.c
> 
> diff --git a/drivers/gpu/drm/panel/Kconfig b/drivers/gpu/drm/panel/Kconfig
> index 718d8ce15b1f..726f3fb3312d 100644
> --- a/drivers/gpu/drm/panel/Kconfig
> +++ b/drivers/gpu/drm/panel/Kconfig
> @@ -82,6 +82,14 @@ config DRM_PANEL_PANASONIC_VVX10F034N00
>   	  WUXGA (1920x1200) Novatek NT1397-based DSI panel as found in some
>   	  Xperia Z2 tablets
>   
> +config DRM_PANEL_RASPBERRYPI_TOUCHSCREEN
> +	tristate "Raspberry Pi 7-inch touchscreen panel"
> +	depends on DRM_MIPI_DSI
> +	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_S6E3HA2
>   	tristate "Samsung S6E3HA2 DSI video mode panel"
>   	depends on OF
> diff --git a/drivers/gpu/drm/panel/Makefile b/drivers/gpu/drm/panel/Makefile
> index c8483fdd5b9b..77ede3467324 100644
> --- a/drivers/gpu/drm/panel/Makefile
> +++ b/drivers/gpu/drm/panel/Makefile
> @@ -5,6 +5,7 @@ obj-$(CONFIG_DRM_PANEL_JDI_LT070ME05000) += panel-jdi-lt070me05000.o
>   obj-$(CONFIG_DRM_PANEL_LG_LG4573) += panel-lg-lg4573.o
>   obj-$(CONFIG_DRM_PANEL_ORISETECH_OTM8009A) += panel-orisetech-otm8009a.o
>   obj-$(CONFIG_DRM_PANEL_PANASONIC_VVX10F034N00) += panel-panasonic-vvx10f034n00.o
> +obj-$(CONFIG_DRM_PANEL_RASPBERRYPI_TOUCHSCREEN) += panel-raspberrypi-touchscreen.o
>   obj-$(CONFIG_DRM_PANEL_SAMSUNG_LD9040) += panel-samsung-ld9040.o
>   obj-$(CONFIG_DRM_PANEL_SAMSUNG_S6E3HA2) += panel-samsung-s6e3ha2.o
>   obj-$(CONFIG_DRM_PANEL_SAMSUNG_S6E63J0X03) += panel-samsung-s6e63j0x03.o
> diff --git a/drivers/gpu/drm/panel/panel-raspberrypi-touchscreen.c b/drivers/gpu/drm/panel/panel-raspberrypi-touchscreen.c
> new file mode 100644
> index 000000000000..4237a0cbcdcc
> --- /dev/null
> +++ b/drivers/gpu/drm/panel/panel-raspberrypi-touchscreen.c
> @@ -0,0 +1,517 @@
> +/*
> + * 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 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, presenting a DSI
> + * device with a drm_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/drm_panel.h>
> +#include <drm/drmP.h>
> +#include <drm/drm_crtc.h>
> +#include <drm/drm_mipi_dsi.h>
> +#include <drm/drm_panel.h>
> +
> +#define RPI_DSI_DRIVER_NAME "rpi-ts-dsi"
> +
> +/* 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_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_panel base;
> +	struct mipi_dsi_device *dsi;
> +	struct i2c_client *i2c;
> +};
> +
> +static const struct drm_display_mode rpi_touchscreen_modes[] = {
> +	{
> +		/* Modeline comes from the Raspberry Pi firmware, with HFP=1
> +		 * plugged in and clock re-computed from that.
> +		 */
> +		.clock = 25979400 / 1000,
> +		.hdisplay = 800,
> +		.hsync_start = 800 + 1,
> +		.hsync_end = 800 + 1 + 2,
> +		.htotal = 800 + 1 + 2 + 46,
> +		.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);
> +}
> +
> +static u8 rpi_touchscreen_i2c_read(struct rpi_touchscreen *ts, u8 reg)
> +{
> +	return i2c_smbus_read_byte_data(ts->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->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 int rpi_touchscreen_disable(struct drm_panel *panel)
> +{
> +	struct rpi_touchscreen *ts = panel_to_ts(panel);
> +
> +	rpi_touchscreen_i2c_write(ts, REG_PWM, 0);
> +
> +	rpi_touchscreen_i2c_write(ts, REG_POWERON, 0);
> +	udelay(1);
> +
> +	return 0;
> +}
> +
> +static int rpi_touchscreen_noop(struct drm_panel *panel)
> +{
> +	return 0;
> +}
> +
> +static int rpi_touchscreen_enable(struct drm_panel *panel)
> +{
> +	struct rpi_touchscreen *ts = panel_to_ts(panel);
> +	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));
> +
> +	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;
> +	static const u32 bus_format = MEDIA_BUS_FMT_RGB888_1X24;
> +
> +	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 = 154;
> +	connector->display_info.height_mm = 86;
> +	drm_display_info_set_bus_formats(&connector->display_info,
> +					 &bus_format, 1);
> +
> +	return num;
> +}
> +
> +static const struct drm_panel_funcs rpi_touchscreen_funcs = {
> +	.disable = rpi_touchscreen_disable,
> +	.unprepare = rpi_touchscreen_noop,
> +	.prepare = rpi_touchscreen_noop,
> +	.enable = rpi_touchscreen_enable,
> +	.get_modes = rpi_touchscreen_get_modes,
> +};
> +
> +static int rpi_touchscreen_probe(struct i2c_client *i2c,
> +				 const struct i2c_device_id *id)
> +{
> +	struct device *dev = &i2c->dev;
> +	struct rpi_touchscreen *ts;
> +	struct device_node *endpoint, *dsi_host_node;
> +	struct mipi_dsi_host *host;
> +	int ret, ver;
> +	struct mipi_dsi_device_info info = {
> +		.type = RPI_DSI_DRIVER_NAME,
> +		.channel = 0,
> +		.node = NULL,
> +	};
> +
> +	ts = devm_kzalloc(dev, sizeof(*ts), GFP_KERNEL);
> +	if (!ts)
> +		return -ENOMEM;
> +
> +	i2c_set_clientdata(i2c, ts);
> +
> +	ts->i2c = i2c;
> +
> +	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);
> +		return -ENODEV;
> +	}
> +
> +	/* Turn off at boot, so we can cleanly sequence powering on. */
> +	rpi_touchscreen_i2c_write(ts, REG_POWERON, 0);
> +
> +	/* Look up the DSI host.  It needs to probe before we do. */
> +	endpoint = of_graph_get_next_endpoint(dev->of_node, NULL);
> +	dsi_host_node = of_graph_get_remote_port_parent(endpoint);
> +	host = of_find_mipi_dsi_host_by_node(dsi_host_node);
> +	of_node_put(dsi_host_node);
> +	if (!host) {
> +		of_node_put(endpoint);
> +		return -EPROBE_DEFER;
> +	}
> +
> +	info.node = of_graph_get_remote_port(endpoint);
> +	of_node_put(endpoint);
> +
> +	ts->dsi = mipi_dsi_device_register_full(host, &info);
> +	if (IS_ERR(ts->dsi)) {
> +		dev_err(dev, "DSI device registration failed: %ld\n",
> +			PTR_ERR(ts->dsi));
> +		return PTR_ERR(ts->dsi);
> +	}
> +
> +	ts->base.dev = dev;
> +	ts->base.funcs = &rpi_touchscreen_funcs;
> +
> +	/* This appears last, as it's what will unblock the DSI host
> +	 * driver's component bind function.
> +	 */
> +	ret = drm_panel_add(&ts->base);
> +	if (ret)
> +		return ret;
> +
> +	return 0;
> +}
> +
> +static int rpi_touchscreen_remove(struct i2c_client *i2c)
> +{
> +	struct rpi_touchscreen *ts = i2c_get_clientdata(i2c);
> +
> +	mipi_dsi_detach(ts->dsi);
> +
> +	drm_panel_remove(&ts->base);
> +
> +	mipi_dsi_device_unregister(ts->dsi);
> +	kfree(ts->dsi);
> +
> +	return 0;
> +}
> +
> +static int rpi_touchscreen_dsi_probe(struct mipi_dsi_device *dsi)
> +{
> +	int ret;
> +
> +	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;
> +
> +	ret = mipi_dsi_attach(dsi);
> +
> +	if (ret)
> +		dev_err(&dsi->dev, "failed to attach dsi to host: %d\n", ret);
> +
> +	return ret;
> +}
> +
> +static struct mipi_dsi_driver rpi_touchscreen_dsi_driver = {
> +	.driver.name = RPI_DSI_DRIVER_NAME,
> +	.probe = rpi_touchscreen_dsi_probe,
> +};
> +
> +static const struct of_device_id rpi_touchscreen_of_ids[] = {
> +	{ .compatible = "raspberrypi,7inch-touchscreen-panel" },
> +	{ } /* sentinel */
> +};
> +MODULE_DEVICE_TABLE(of, rpi_touchscreen_of_ids);
> +
> +static struct i2c_driver rpi_touchscreen_driver = {
> +	.driver = {
> +		.name = "rpi_touchscreen",
> +		.of_match_table = rpi_touchscreen_of_ids,
> +	},
> +	.probe = rpi_touchscreen_probe,
> +	.remove = rpi_touchscreen_remove,
> +};
> +
> +static int __init rpi_touchscreen_init(void)
> +{
> +	mipi_dsi_driver_register(&rpi_touchscreen_dsi_driver);
> +	return i2c_add_driver(&rpi_touchscreen_driver);
> +}
> +module_init(rpi_touchscreen_init);
> +
> +static void __exit rpi_touchscreen_exit(void)
> +{
> +	i2c_del_driver(&rpi_touchscreen_driver);
> +	mipi_dsi_driver_unregister(&rpi_touchscreen_dsi_driver);
> +}
> +module_exit(rpi_touchscreen_exit);
> +
> +MODULE_AUTHOR("Eric Anholt <eric@...olt.net>");
> +MODULE_DESCRIPTION("Raspberry Pi 7-inch touchscreen driver");
> +MODULE_LICENSE("GPL v2");
> 

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