[PATCH v2 0/2] input: driver for RPi's official 7" touchscreen

[PATCH v2 0/2] input: driver for RPi's official 7" touchscreen

[Nicolas Saenz Julienne]

This small series adds support for Raspberry pi's 7" touchscreen. Which
alongside with the backlight driver are the last devices needed to have
a functional touchscreen upstream.

With this setup the board's VC4 firmware takes care of communicating
with the touch chip and provides data though a shared memory area
provided by the driver. The driver takes care of polling the firmware
whenever at around 60Hz since there is no interrupt line available.

The 1.0 revision of the touchscreen is based on the ft5426 chip.
Technically, with some changes in edt-ft54x4.c we should be able to
access the data directly through I2C. Yet this bus is meant to be owned
by RPi's firmware and might access it anytime. For example, to
configure RPi's camera device. As sharing the bus master interface is
not possible a series of alternatives have been tested unsuccessfully
[1]. It seems that we'll be unable to access the chip directly in a
"clean" way which leaves us with this firmware based solution.

The driver was rewritten based on the one available on the downstream
Raspberry Pi kernel tree: https://github.com/raspberrypi/linux/.

This series is based on v4.20-rc6 and was tested on a RPi 3 B+.

Changelog

v1 -> v2:
  - Remove all references to RPi3
  - Spelling errors
  - Rename config string
  - Reorder devm_add_action_or_reset()
  - Remove __set_bit(EV* functions
  - Remove INPUT_MT_POINTER flag
  - Add missing header files
  - Create define to invalidate npointers
  - Fix commit ordering and titles

RFC -> PATCH:
  - Better dependencies check in Kconfig
  - Add SPDX tag
  - Use polled input device API
  - Use input_mt_sync_frame()
  - Drop reference from dt node in probe
  - Use devm where possible
  - Small cosmetic changes

[1] https://lists.infradead.org/pipermail/linux-rpi-kernel/2018-December/008444.html
===

Nicolas Saenz Julienne (2):
  dt-bindings: input: Add Raspberry Pi Touchscreen
  input: add official Raspberry Pi's touchscreen driver

 .../touchscreen/raspberrypi,firmware-ts.txt   |  26 ++
 drivers/input/touchscreen/Kconfig             |  12 +
 drivers/input/touchscreen/Makefile            |   1 +
 drivers/input/touchscreen/raspberrypi-ts.c    | 227 ++++++++++++++++++
 4 files changed, 266 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/input/touchscreen/raspberrypi,firmware-ts.txt
 create mode 100644 drivers/input/touchscreen/raspberrypi-ts.c

-- 
2.19.2

[PATCH v2 1/2] dt-bindings: input: Add Raspberry Pi Touchscreen

[Nicolas Saenz Julienne]

Adds device tree documentation for Raspberry Pi's official 7"
touchscreen.

This binding is meant to be used as an overlay.

Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
---
 .../touchscreen/raspberrypi,firmware-ts.txt   | 26 +++++++++++++++++++
 1 file changed, 26 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/input/touchscreen/raspberrypi,firmware-ts.txt

diff --git a/Documentation/devicetree/bindings/input/touchscreen/raspberrypi,firmware-ts.txt b/Documentation/devicetree/bindings/input/touchscreen/raspberrypi,firmware-ts.txt
new file mode 100644
index 000000000000..2a1af240ccc3
--- /dev/null
+++ b/Documentation/devicetree/bindings/input/touchscreen/raspberrypi,firmware-ts.txt
@@ -0,0 +1,26 @@
+Raspberry Pi firmware based 7" touchscreen
+=====================================
+
+Required properties:
+ - compatible: "raspberrypi,firmware-ts"
+
+Optional properties:
+ - firmware: Reference to RPi's firmware device node
+ - touchscreen-size-x: See touchscreen.txt
+ - touchscreen-size-y: See touchscreen.txt
+ - touchscreen-inverted-x: See touchscreen.txt
+ - touchscreen-inverted-y: See touchscreen.txt
+ - touchscreen-swapped-x-y: See touchscreen.txt
+
+Example:
+
+firmware: firmware-rpi {
+	compatible = "raspberrypi,bcm2835-firmware";
+	mboxes = <&mailbox>;
+
+	ts: touchscreen {
+		compatible = "raspberrypi,firmware-ts";
+		touchscreen-size-x = <800>;
+		touchscreen-size-y = <480>;
+	};
+};
-- 
2.19.2

Re: [PATCH v2 1/2] dt-bindings: input: Add Raspberry Pi Touchscreen

[Rob Herring]

On Tue, 11 Dec 2018 12:23:53 +0100, Nicolas Saenz Julienne wrote:
> Adds device tree documentation for Raspberry Pi's official 7"
> touchscreen.
> 
> This binding is meant to be used as an overlay.
> 
> Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
> ---
>  .../touchscreen/raspberrypi,firmware-ts.txt   | 26 +++++++++++++++++++
>  1 file changed, 26 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/input/touchscreen/raspberrypi,firmware-ts.txt
> 

Reviewed-by: Rob Herring <robh@kernel.org>

Re: [PATCH v2 1/2] dt-bindings: input: Add Raspberry Pi Touchscreen

[Rob Herring]

On Tue, 11 Dec 2018 12:23:53 +0100, Nicolas Saenz Julienne wrote:
> Adds device tree documentation for Raspberry Pi's official 7"
> touchscreen.
> 
> This binding is meant to be used as an overlay.
> 
> Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
> ---
>  .../touchscreen/raspberrypi,firmware-ts.txt   | 26 +++++++++++++++++++
>  1 file changed, 26 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/input/touchscreen/raspberrypi,firmware-ts.txt
> 

Reviewed-by: Rob Herring <robh@kernel.org>

[PATCH v2 2/2] input: add official Raspberry Pi's touchscreen driver

[Nicolas Saenz Julienne]

Add's support to Raspberry Pi's 7" Touch device. Instead of using a
conventional bus all information is copied into a memory mapped area by
RPi's firmware.

Based on the driver found in RPi's kernel repository.

Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
---
 drivers/input/touchscreen/Kconfig          |  12 ++
 drivers/input/touchscreen/Makefile         |   1 +
 drivers/input/touchscreen/raspberrypi-ts.c | 227 +++++++++++++++++++++
 3 files changed, 240 insertions(+)
 create mode 100644 drivers/input/touchscreen/raspberrypi-ts.c

diff --git a/drivers/input/touchscreen/Kconfig b/drivers/input/touchscreen/Kconfig
index 2a80675cfd94..af6027cc7bbf 100644
--- a/drivers/input/touchscreen/Kconfig
+++ b/drivers/input/touchscreen/Kconfig
@@ -696,6 +696,18 @@ config TOUCHSCREEN_EDT_FT5X06
 	  To compile this driver as a module, choose M here: the
 	  module will be called edt-ft5x06.
 
+config TOUCHSCREEN_RASPBERRYPI_FW
+	tristate "Raspberry Pi's firmware base touch screen support"
+	depends on RASPBERRYPI_FIRMWARE || COMPILE_TEST
+	help
+	  Say Y here if you have the official Raspberry Pi 7 inch screen on
+	  your system.
+
+	  If unsure, say N.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called raspberrypi-ts.
+
 config TOUCHSCREEN_MIGOR
 	tristate "Renesas MIGO-R touchscreen"
 	depends on (SH_MIGOR || COMPILE_TEST) && I2C
diff --git a/drivers/input/touchscreen/Makefile b/drivers/input/touchscreen/Makefile
index 5911a4190cd2..fcc7605fba8d 100644
--- a/drivers/input/touchscreen/Makefile
+++ b/drivers/input/touchscreen/Makefile
@@ -109,3 +109,4 @@ obj-$(CONFIG_TOUCHSCREEN_ZET6223)	+= zet6223.o
 obj-$(CONFIG_TOUCHSCREEN_ZFORCE)	+= zforce_ts.o
 obj-$(CONFIG_TOUCHSCREEN_COLIBRI_VF50)	+= colibri-vf50-ts.o
 obj-$(CONFIG_TOUCHSCREEN_ROHM_BU21023)	+= rohm_bu21023.o
+obj-$(CONFIG_TOUCHSCREEN_RASPBERRYPI_FW)	+= raspberrypi-ts.o
diff --git a/drivers/input/touchscreen/raspberrypi-ts.c b/drivers/input/touchscreen/raspberrypi-ts.c
new file mode 100644
index 000000000000..7f8873eb2379
--- /dev/null
+++ b/drivers/input/touchscreen/raspberrypi-ts.c
@@ -0,0 +1,227 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Raspberry Pi firmware based touchscreen driver
+ *
+ * Copyright (C) 2015, 2017 Raspberry Pi
+ * Copyright (C) 2018 Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
+ */
+
+#include <linux/io.h>
+#include <linux/of.h>
+#include <linux/slab.h>
+#include <linux/device.h>
+#include <linux/module.h>
+#include <linux/bitops.h>
+#include <linux/dma-mapping.h>
+#include <linux/platform_device.h>
+#include <linux/input.h>
+#include <linux/input/mt.h>
+#include <linux/input-polldev.h>
+#include <linux/input/touchscreen.h>
+#include <soc/bcm2835/raspberrypi-firmware.h>
+
+#define RPI_TS_DEFAULT_WIDTH	800
+#define RPI_TS_DEFAULT_HEIGHT	480
+
+#define RPI_TS_MAX_SUPPORTED_POINTS	10
+
+#define RPI_TS_FTS_TOUCH_DOWN		0
+#define RPI_TS_FTS_TOUCH_CONTACT	2
+
+#define RPI_TS_POLL_INTERVAL		17	/* 60fps */
+
+#define RPI_TS_NPOINTS_REG_INVALIDATE	99
+
+struct rpi_ts {
+	struct platform_device *pdev;
+	struct input_polled_dev *poll_dev;
+	struct touchscreen_properties prop;
+
+	void __iomem *fw_regs_va;
+	dma_addr_t fw_regs_phys;
+
+	int known_ids;
+};
+
+struct rpi_ts_regs {
+	u8 device_mode;
+	u8 gesture_id;
+	u8 num_points;
+	struct rpi_ts_touch {
+		u8 xh;
+		u8 xl;
+		u8 yh;
+		u8 yl;
+		u8 pressure; /* Not supported */
+		u8 area;     /* Not supported */
+	} point[RPI_TS_MAX_SUPPORTED_POINTS];
+};
+
+static void rpi_ts_poll(struct input_polled_dev *dev)
+{
+	struct input_dev *input = dev->input;
+	struct rpi_ts *ts = dev->private;
+	struct rpi_ts_regs regs;
+	int modified_ids = 0;
+	long released_ids;
+	int event_type;
+	int touchid;
+	int x, y;
+	int i;
+
+	memcpy_fromio(&regs, ts->fw_regs_va, sizeof(regs));
+	/*
+	 * We poll the memory based register copy of the touchscreen chip using
+	 * the number of points register to know whether the copy has been
+	 * updated (we write 99 to the memory copy, the GPU will write between
+	 * 0 - 10 points)
+	 */
+	iowrite8(RPI_TS_NPOINTS_REG_INVALIDATE,
+		 ts->fw_regs_va + offsetof(struct rpi_ts_regs, num_points));
+
+	if (regs.num_points == RPI_TS_NPOINTS_REG_INVALIDATE ||
+	    (regs.num_points == 0 && ts->known_ids == 0))
+	    return;
+
+	for (i = 0; i < regs.num_points; i++) {
+		x = (((int)regs.point[i].xh & 0xf) << 8) + regs.point[i].xl;
+		y = (((int)regs.point[i].yh & 0xf) << 8) + regs.point[i].yl;
+		touchid = (regs.point[i].yh >> 4) & 0xf;
+		event_type = (regs.point[i].xh >> 6) & 0x03;
+
+		modified_ids |= BIT(touchid);
+
+		if (event_type == RPI_TS_FTS_TOUCH_DOWN ||
+		    event_type == RPI_TS_FTS_TOUCH_CONTACT) {
+			input_mt_slot(input, touchid);
+			input_mt_report_slot_state(input, MT_TOOL_FINGER, 1);
+			touchscreen_report_pos(input, &ts->prop, x, y, true);
+		}
+	}
+
+	released_ids = ts->known_ids & ~modified_ids;
+	for_each_set_bit(i, &released_ids, RPI_TS_MAX_SUPPORTED_POINTS) {
+		input_mt_slot(input, i);
+		input_mt_report_slot_state(input, MT_TOOL_FINGER, 0);
+		modified_ids &= ~(BIT(i));
+	}
+	ts->known_ids = modified_ids;
+
+	input_mt_sync_frame(input);
+	input_sync(input);
+}
+
+static void rpi_ts_dma_cleanup(void *data)
+{
+	struct rpi_ts *ts = data;
+	struct device *dev = &ts->pdev->dev;
+
+	dma_free_coherent(dev, PAGE_SIZE, ts->fw_regs_va, ts->fw_regs_phys);
+}
+
+static int rpi_ts_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct device_node *np = dev->of_node;
+	struct input_polled_dev *poll_dev;
+	struct device_node *fw_node;
+	struct rpi_firmware *fw;
+	struct input_dev *input;
+	struct rpi_ts *ts;
+	u32 touchbuf;
+	int error;
+
+	fw_node = of_get_parent(np);
+	if (!fw_node) {
+		dev_err(dev, "Missing firmware node\n");
+		return -ENOENT;
+	}
+
+	fw = rpi_firmware_get(fw_node);
+	of_node_put(fw_node);
+	if (!fw)
+		return -EPROBE_DEFER;
+
+	ts = devm_kzalloc(dev, sizeof(*ts), GFP_KERNEL);
+	if (!ts)
+		return -ENOMEM;
+	ts->pdev = pdev;
+
+	ts->fw_regs_va = dma_zalloc_coherent(dev, PAGE_SIZE, &ts->fw_regs_phys,
+					     GFP_KERNEL);
+	if (!ts->fw_regs_va) {
+		dev_err(dev, "failed to dma_alloc_coherent\n");
+		return -ENOMEM;
+	}
+
+	error = devm_add_action_or_reset(dev, rpi_ts_dma_cleanup, ts);
+	if (error) {
+		dev_err(dev, "failed to devm_add_action_or_reset, %d\n", error);
+		return error;
+	}
+
+
+	touchbuf = (u32)ts->fw_regs_phys;
+	error = rpi_firmware_property(fw, RPI_FIRMWARE_FRAMEBUFFER_SET_TOUCHBUF,
+				      &touchbuf, sizeof(touchbuf));
+
+	if (error || touchbuf != 0) {
+		dev_warn(dev, "Failed to set touchbuf, %d\n", error);
+		return error;
+	}
+
+	poll_dev = devm_input_allocate_polled_device(dev);
+	if (!poll_dev) {
+		dev_err(dev, "Failed to allocate input device\n");
+		return -ENOMEM;
+	}
+	ts->poll_dev = poll_dev;
+	input = poll_dev->input;
+
+	input->name = "raspberrypi-ts";
+	input->id.bustype = BUS_HOST;
+	poll_dev->poll_interval = RPI_TS_POLL_INTERVAL;
+	poll_dev->poll = rpi_ts_poll;
+	poll_dev->private = ts;
+
+	input_set_abs_params(input, ABS_MT_POSITION_X, 0,
+			     RPI_TS_DEFAULT_WIDTH, 0, 0);
+	input_set_abs_params(input, ABS_MT_POSITION_Y, 0,
+			     RPI_TS_DEFAULT_HEIGHT, 0, 0);
+	touchscreen_parse_properties(input, true, &ts->prop);
+
+	error = input_mt_init_slots(input, RPI_TS_MAX_SUPPORTED_POINTS,
+				    INPUT_MT_DIRECT);
+	if (error) {
+		dev_err(dev, "could not init mt slots, %d\n", error);
+		return error;
+	}
+
+	error = input_register_polled_device(poll_dev);
+	if (error) {
+		dev_err(dev, "could not register input device, %d\n", error);
+		return error;
+	}
+
+	return 0;
+}
+
+static const struct of_device_id rpi_ts_match[] = {
+	{ .compatible = "raspberrypi,firmware-ts", },
+	{},
+};
+MODULE_DEVICE_TABLE(of, rpi_ts_match);
+
+static struct platform_driver rpi_ts_driver = {
+	.driver = {
+		.name   = "raspberrypi-ts",
+		.of_match_table = rpi_ts_match,
+	},
+	.probe          = rpi_ts_probe,
+};
+module_platform_driver(rpi_ts_driver);
+
+MODULE_AUTHOR("Gordon Hollingworth");
+MODULE_AUTHOR("Nicolas Saenz Julienne <nsaenzjulienne@suse.de>");
+MODULE_DESCRIPTION("Raspberry Pi firmware based touchscreen driver");
+MODULE_LICENSE("GPL v2");
-- 
2.19.2

Re: [PATCH v2 2/2] input: add official Raspberry Pi's touchscreen driver

[Eric Anholt]

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Nicolas Saenz Julienne <nsaenzjulienne@suse.de> writes:

> Add's support to Raspberry Pi's 7" Touch device. Instead of using a
> conventional bus all information is copied into a memory mapped area by
> RPi's firmware.
>
> Based on the driver found in RPi's kernel repository.
>
> Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>

While I wish we could just have a native driver instead, it does make
sense to have this driver upstream given the constraints.

Acked-by: Eric Anholt <eric@anholt.net>

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Re: [PATCH v2 2/2] input: add official Raspberry Pi's touchscreen driver

[Eric Anholt]

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Nicolas Saenz Julienne <nsaenzjulienne@suse.de> writes:

> Add's support to Raspberry Pi's 7" Touch device. Instead of using a
> conventional bus all information is copied into a memory mapped area by
> RPi's firmware.
>
> Based on the driver found in RPi's kernel repository.
>
> Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>

While I wish we could just have a native driver instead, it does make
sense to have this driver upstream given the constraints.

Acked-by: Eric Anholt <eric@anholt.net>

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Re: [PATCH v2 2/2] input: add official Raspberry Pi's touchscreen driver

[Nicolas Saenz Julienne]

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On Thu, 2018-12-20 at 10:39 -0800, Eric Anholt wrote:
> Nicolas Saenz Julienne <nsaenzjulienne@suse.de> writes:
> 
> > Add's support to Raspberry Pi's 7" Touch device. Instead of using a
> > conventional bus all information is copied into a memory mapped
> > area by
> > RPi's firmware.
> > 
> > Based on the driver found in RPi's kernel repository.
> > 
> > Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
> 
> While I wish we could just have a native driver instead, it does make
> sense to have this driver upstream given the constraints.
> 
> Acked-by: Eric Anholt <eric@anholt.net>

Thanks Eric.

FYI I did manage to access the touchscreen after altering the native
driver (edt-ft5x06). That said, as commented in the cover letter, it's
not good enough as it breaks the camera. I plan on posting the patch
and an overlay. I'm just waiting to see how these first patches are
received.

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Re: [PATCH v2 2/2] input: add official Raspberry Pi's touchscreen driver

[Dmitry Torokhov]

On Thu, Dec 20, 2018 at 08:12:23PM +0100, Nicolas Saenz Julienne wrote:
> On Thu, 2018-12-20 at 10:39 -0800, Eric Anholt wrote:
> > Nicolas Saenz Julienne <nsaenzjulienne@suse.de> writes:
> > 
> > > Add's support to Raspberry Pi's 7" Touch device. Instead of using a
> > > conventional bus all information is copied into a memory mapped
> > > area by
> > > RPi's firmware.
> > > 
> > > Based on the driver found in RPi's kernel repository.
> > > 
> > > Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
> > 
> > While I wish we could just have a native driver instead, it does make
> > sense to have this driver upstream given the constraints.
> > 
> > Acked-by: Eric Anholt <eric@anholt.net>
> 
> Thanks Eric.
> 
> FYI I did manage to access the touchscreen after altering the native
> driver (edt-ft5x06). That said, as commented in the cover letter, it's
> not good enough as it breaks the camera. I plan on posting the patch
> and an overlay. I'm just waiting to see how these first patches are
> received.

Applied, thank you.

-- 
Dmitry