Date:   Sat, 8 Dec 2018 20:43:52 -0800
From:   Dmitry Torokhov <dmitry.torokhov@...il.com>
To:     Nicolas Saenz Julienne <nsaenzjulienne@...e.de>
Cc:     Henrik Rydberg <rydberg@...math.org>,
        linux-rpi-kernel@...ts.infradead.org, stefan.wahren@...e.com,
        eric@...olt.net, agraf@...e.de,
        Corentin Labbe <clabbe.montjoie@...il.com>,
        Rob Herring <robh@...nel.org>,
        Hans de Goede <hdegoede@...hat.com>,
        Masanari Iida <standby24x7@...il.com>,
        Zhu Yi <yi.zhu5@...bosch.com>,
        Eugen Hristev <eugen.hristev@...rochip.com>,
        Jonathan Cameron <Jonathan.Cameron@...wei.com>,
        Hans-Christian Noren Egtvedt <egtvedt@...fundet.no>,
        Heiko Schocher <hs@...x.de>, linux-kernel@...r.kernel.org,
        linux-input@...r.kernel.org
Subject: Re: [PATCH RFC 1/2] input: add official Raspberry Pi's 7"
 touchscreen driver

Hi Nicolas,

On Wed, Dec 05, 2018 at 11:09:03PM +0100, Nicolas Saenz Julienne wrote:
> Adds support to Raspberry Pi's 7" touchscreen device. Instead of using
> a conventional bus all information is copied into a memory mapped area
> by RPi's VC4 firmware.
> 
> Based on the driver found in RPi's downstream kernel repository.
> 
> Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@...e.de>
> ---
>  drivers/input/touchscreen/Kconfig          |  12 +
>  drivers/input/touchscreen/Makefile         |   1 +
>  drivers/input/touchscreen/raspberrypi-ts.c | 252 +++++++++++++++++++++
>  3 files changed, 265 insertions(+)
>  create mode 100644 drivers/input/touchscreen/raspberrypi-ts.c
> 
> diff --git a/drivers/input/touchscreen/Kconfig b/drivers/input/touchscreen/Kconfig
> index 2a80675cfd94..8d0fcb3dc8a8 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_TS
> +	tristate "Raspberry Pi's firmware base touch screen support"
> +	depends on OF

I think "depends on ASPBERRYPI_FIRMWARE || COMPILE_TEST" is more
precise dependency.

> +	help
> +	  Say Y here if you have the official Raspberry Pi 7' touchscren
> +	  connected 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..3eccb1925e89 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_TS)	+= 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..9d29411a5674
> --- /dev/null
> +++ b/drivers/input/touchscreen/raspberrypi-ts.c
> @@ -0,0 +1,252 @@
> +/*
> + * Raspberry Pi 3 firmware based touchscreen driver
> + *
> + * Copyright (C) 2015, 2017 Raspberry Pi
> + * Copyright (C) 2018 Nicolas Saenz Julienne <nsaenzjulienne@...e.de>
> + *
> + * 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.

Please use SPDX tag for the license.

> + */
> +
> +#include <linux/io.h>
> +#include <linux/slab.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/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
> +
> +struct rpi_ts {
> +	struct input_dev *input;

Since the only way is to poll, please use polled input device instead of
standard one. It will take care of scheduling polling, stopping it when
needed, etc.

> +	struct touchscreen_properties prop;
> +
> +	void __iomem *ts_base;
> +	dma_addr_t bus_addr;
> +
> +	struct delayed_work work;
> +	int known_ids;
> +};
> +
> +struct rpi_ts_regs {
> +	uint8_t device_mode;
> +	uint8_t gesture_id;
> +	uint8_t num_points;

Simply u8 in kernel.

> +	struct rpi_ts_touch {
> +		uint8_t xh;
> +		uint8_t xl;
> +		uint8_t yh;
> +		uint8_t yl;
> +		uint8_t pressure; /* Not supported */
> +		uint8_t area;     /* Not supported */
> +	} point[RPI_TS_MAX_SUPPORTED_POINTS];
> +};
> +
> +/*
> + * This process polls the memory based register copy of the touch screen chip
> + * registers 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)
> + */
> +static void rpi_ts_work(struct work_struct *work)
> +{
> +	struct rpi_ts *ts = container_of(work, struct rpi_ts, work.work);
> +	struct input_dev *input = ts->input;
> +	struct rpi_ts_regs regs;
> +	int modified_ids = 0;
> +	int released_ids;
> +	int event_type;
> +	int touchid;
> +	int x, y;
> +	int i;
> +
> +	memcpy_fromio(&regs, ts->ts_base, sizeof(struct rpi_ts_regs));
> +	iowrite8(99, ts->ts_base + offsetof(struct rpi_ts_regs, num_points));
> +
> +	if (regs.num_points == 99 ||
> +	    (regs.num_points == 0 && ts->known_ids == 0))
> +	    goto out;
> +
> +	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 (i = 0; released_ids && i < RPI_TS_MAX_SUPPORTED_POINTS; i++) {

If you make released_ids long instead of int you can use
for_each_set_bit() here.

> +		if (released_ids & BIT(i)) {
> +			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_report_pointer_emulation(ts->input, true);

input_mt_sync_frame() and then you would not need to call
input_mt_report_pointer_emulation() if you passed right flags to
input_mt_init_slots().

> +	input_sync(ts->input);
> +
> +out:
> +	schedule_delayed_work(&ts->work, msecs_to_jiffies(17)); /* 60 fps */
> +}
> +
> +static int rpi_ts_open(struct input_dev *dev)
> +{
> +	struct rpi_ts *ts = input_get_drvdata(dev);
> +
> +	schedule_delayed_work(&ts->work, 0);
> +
> +	return 0;
> +}
> +
> +static void rpi_ts_close(struct input_dev *dev)
> +{
> +	struct rpi_ts *ts = input_get_drvdata(dev);
> +
> +	cancel_delayed_work_sync(&ts->work);
> +}

Not needed if using polled input device.

> +
> +static int rpi_ts_probe(struct platform_device *pdev)
> +{
> +	struct device *dev = &pdev->dev;
> +	struct device_node *np = dev->of_node;
> +	struct device_node *fw_node;
> +	struct input_dev *input;
> +	struct rpi_firmware *fw;
> +	struct rpi_ts *ts;
> +	u32 touchbuf;
> +	int err = 0;
> +
> +	fw_node = of_get_parent(np);
> +	if (!fw_node) {
> +		dev_err(dev, "Missing firmware node\n");
> +		return -ENOENT;
> +	}
> +
> +	fw = rpi_firmware_get(fw_node);

You are leaking node here I believe. Stick of_node_put() after
rpi_firmware_get() and before "if".

> +	if (!fw)
> +		return -EPROBE_DEFER;
> +
> +	ts = devm_kzalloc(dev, sizeof(struct rpi_ts), GFP_KERNEL);

sizeof(*ts)

> +	if (!ts) {
> +		dev_err(dev, "Failed to allocate memory\n");
> +		return -ENOMEM;
> +	}
> +
> +	input = input_allocate_device();

devm.

> +	if (!input) {
> +		dev_err(dev, "Failed to allocate input device\n");
> +		return -ENOMEM;
> +	}
> +	ts->input = input;
> +
> +	ts->ts_base = dma_zalloc_coherent(dev, PAGE_SIZE, &ts->bus_addr,
> +					  GFP_KERNEL);
> +	if (!ts->ts_base) {
> +		dev_err(dev, "failed to dma_alloc_coherent\n");
> +		err = -ENOMEM;
> +		goto undegister_input_device;
> +	}
> +
> +	touchbuf = (u32)ts->bus_addr;
> +	err = rpi_firmware_property(fw, RPI_FIRMWARE_FRAMEBUFFER_SET_TOUCHBUF,
> +				    &touchbuf, sizeof(touchbuf));
> +
> +	if (err || touchbuf != 0) {
> +		dev_warn(dev, "Failed to set touchbuf, trying to get err:%x\n",
> +			 err);
> +		goto clean_dma_buf;
> +	}
> +
> +	INIT_DELAYED_WORK(&ts->work, rpi_ts_work);
> +	platform_set_drvdata(pdev, ts);
> +
> +	input->name = "raspberrypi-ts";
> +	input->id.bustype = BUS_HOST;
> +	input->open = rpi_ts_open;
> +	input->close = rpi_ts_close;
> +	input->dev.parent = &pdev->dev;
> +
> +	__set_bit(EV_KEY, input->evbit);
> +	__set_bit(EV_SYN, input->evbit);
> +	__set_bit(EV_ABS, input->evbit);
> +
> +	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);
> +
> +	input_mt_init_slots(input, RPI_TS_MAX_SUPPORTED_POINTS,
> +			    INPUT_MT_DIRECT);
> +
> +	input_set_drvdata(input, ts);
> +
> +	err = input_register_device(input);
> +	if (err) {
> +		dev_err(dev, "could not register input device, %d\n",
> +			err);
> +		goto clean_dma_buf;
> +	}
> +	return 0;
> +
> +clean_dma_buf:
> +	dma_free_coherent(dev, PAGE_SIZE, ts->ts_base, ts->bus_addr);

I wild make freeing this area a devm custom action
(devm_add_action_or_reset). Then you can get rid of rpi_ts_remove().

> +undegister_input_device:
> +	input_unregister_device(ts->input);
> +
> +	return err;
> +}
> +
> +static int rpi_ts_remove(struct platform_device *pdev)
> +{
> +	struct rpi_ts *ts = (struct rpi_ts *)platform_get_drvdata(pdev);
> +
> +	input_unregister_device(ts->input);
> +	dma_free_coherent(&pdev->dev, PAGE_SIZE, ts->ts_base, ts->bus_addr);
> +	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",
> +		.owner  = THIS_MODULE,

I am pretty sure we no longer need to set owner explicitly.

> +		.of_match_table = rpi_ts_match,
> +	},
> +	.probe          = rpi_ts_probe,
> +	.remove         = rpi_ts_remove,
> +};
> +
> +module_platform_driver(rpi_ts_driver);
> +
> +MODULE_AUTHOR("Gordon Hollingworth");
> +MODULE_AUTHOR("Nicolas Saenz Julienne <nsaenzjulienne@...e.de>");
> +MODULE_DESCRIPTION("Raspberry Pi 3 firmware based touchscreen driver");
> +MODULE_LICENSE("GPL");

This should be "GPL v2" to math the license notice at the top of the
file.

Thanks.

-- 
Dmitry

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