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

From: Dmitry Torokhov
Date: Mon Dec 10 2018 - 14:02:19 EST


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