Re: [PATCH 1/2] input: add official Raspberry Pi's touchscreen driver

[Dmitry Torokhov]

Hi Nicolas,

On Mon, Dec 10, 2018 at 05:30:20PM +0100, Nicolas Saenz Julienne wrote:
> 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.

I believe we are almost there, just a couple of nits.

> 
> Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@xxxxxxx>
> ---
>  drivers/input/touchscreen/Kconfig          |  12 ++
>  drivers/input/touchscreen/Makefile         |   1 +
>  drivers/input/touchscreen/raspberrypi-ts.c | 223 +++++++++++++++++++++
>  3 files changed, 236 insertions(+)
>  create mode 100644 drivers/input/touchscreen/raspberrypi-ts.c
> 
> diff --git a/drivers/input/touchscreen/Kconfig b/drivers/input/touchscreen/Kconfig
> index 2a80675cfd94..a9be434de738 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 RASPBERRYPI_FIRMWARE || COMPILE_TEST
> +	help
> +	  Say Y here if you have the offitial Raspberry Pi 7' scren 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..edc92018687e
> --- /dev/null
> +++ b/drivers/input/touchscreen/raspberrypi-ts.c
> @@ -0,0 +1,223 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Raspberry Pi 3 firmware based touchscreen driver
> + *
> + * Copyright (C) 2015, 2017 Raspberry Pi
> + * Copyright (C) 2018 Nicolas Saenz Julienne <nsaenzjulienne@xxxxxxx>
> + */
> +
> +#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-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 */
> +
> +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];
> +};
> +
> +/*
> + * 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)
> + */
> +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));
> +	iowrite8(99, ts->fw_regs_va + offsetof(struct rpi_ts_regs, num_points));
> +
> +	if (regs.num_points == 99 ||
> +	    (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;
> +
> +	if(ts->fw_regs_va)

Drop the condition.

> +		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 ret;
> +
> +	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) {
> +		dev_err(dev, "Failed to allocate memory\n");
> +		return -ENOMEM;
> +	}
> +	ts->pdev = pdev;
> +
> +	ret = devm_add_action_or_reset(dev, rpi_ts_dma_cleanup, ts);
> +	if (ret)
> +		return ret;

This call needs to be after dma_zalloc_coherent(). Also (my personal
preference) can we please call this variable "error"? Then we can write
"if (error) ...".

> +
> +	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;
> +	}
> +
> +	touchbuf = (u32)ts->fw_regs_phys;
> +	ret = rpi_firmware_property(fw, RPI_FIRMWARE_FRAMEBUFFER_SET_TOUCHBUF,
> +				    &touchbuf, sizeof(touchbuf));
> +
> +	if (ret || touchbuf != 0) {
> +		dev_warn(dev, "Failed to set touchbuf, trying to get err:%x\n",
> +			 ret);
> +		return ret;
> +	}
> +
> +	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;
> +
> +	__set_bit(EV_SYN, input->evbit);
> +	__set_bit(EV_KEY, input->evbit);
> +	__set_bit(EV_ABS, input->evbit);

No need to set these, EV_SYN is set by the input core, and KEY/ABS are
by input_set_abs_params() and input_mt_init_slots().

> +
> +	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_MT_POINTER);

Error handling here please. Also, for touchscreens you do not need to
set INPUT_MT_POINTER, just INPUT_MT_DIRECT.

> +
> +	ret = input_register_polled_device(poll_dev);
> +	if (ret) {
> +		dev_err(dev, "could not register input device, %d\n", ret);
> +		return ret;
> +	}
> +
> +	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@xxxxxxx>");
> +MODULE_DESCRIPTION("Raspberry Pi 3 firmware based touchscreen driver");
> +MODULE_LICENSE("GPL v2");
> -- 
> 2.19.2
> 

Thanks.

-- 
Dmitry