Re: [PATCH 2/2] Input: add touchscreen support for TS-4800

[Dmitry Torokhov <dmitry.torokhov-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>]

Hi Damien,

On Thu, Dec 10, 2015 at 11:11:12AM -0500, Damien Riegel wrote:
> On this board, the touchscreen, an ads7843, is not handled directly by
> Linux but by a companion FPGA. This FPGA is memory-mapped and the IP
> design is very similar to the mk712.
>
> This commit adds the support for this IP.
>
> Signed-off-by: Damien Riegel <damien.riegel-4ysUXcep3aM1wj+D4I0NRVaTQe2KTcn/@public.gmane.org>
> ---
>  drivers/input/touchscreen/Kconfig     |  15 +++
>  drivers/input/touchscreen/Makefile    |   1 +
>  drivers/input/touchscreen/ts4800-ts.c | 238 ++++++++++++++++++++++++++++++++++
>  3 files changed, 254 insertions(+)
>  create mode 100644 drivers/input/touchscreen/ts4800-ts.c
>
> diff --git a/drivers/input/touchscreen/Kconfig b/drivers/input/touchscreen/Kconfig
> index deb14c1..2d3b2f2 100644
> --- a/drivers/input/touchscreen/Kconfig
> +++ b/drivers/input/touchscreen/Kconfig
> @@ -914,6 +914,21 @@ config TOUCHSCREEN_TOUCHIT213
>    To compile this driver as a module, choose M here: the
>    module will be called touchit213.
>  
> +config TOUCHSCREEN_TS4800
> + tristate "TS-4800 touchscreen"
> + depends on HAS_IOMEM && OF
> + select MFD_SYSCON

You also need "select INPUT_POLLDEV" here.

> + help
> +  Say Y here if you have a touchscreen on a TS-4800 board.
> +
> +  On TS-4800, the touchscreen is not handled directly by Linux but by
> +  a companion FPGA.
> +
> +  If unsure, say N.
> +
> +  To compile this driver as a module, choose M here: the
> +  module will be called ts4800_ts.
> +
>  config TOUCHSCREEN_TSC_SERIO
>   tristate "TSC-10/25/40 serial touchscreen support"
>   select SERIO
> diff --git a/drivers/input/touchscreen/Makefile b/drivers/input/touchscreen/Makefile
> index 1b79cc0..5d81ba8c 100644
> --- a/drivers/input/touchscreen/Makefile
> +++ b/drivers/input/touchscreen/Makefile
> @@ -67,6 +67,7 @@ obj-$(CONFIG_TOUCHSCREEN_TI_AM335X_TSC) += ti_am335x_tsc.o
>  obj-$(CONFIG_TOUCHSCREEN_TOUCHIT213) += touchit213.o
>  obj-$(CONFIG_TOUCHSCREEN_TOUCHRIGHT) += touchright.o
>  obj-$(CONFIG_TOUCHSCREEN_TOUCHWIN) += touchwin.o
> +obj-$(CONFIG_TOUCHSCREEN_TS4800) += ts4800-ts.o
>  obj-$(CONFIG_TOUCHSCREEN_TSC_SERIO) += tsc40.o
>  obj-$(CONFIG_TOUCHSCREEN_TSC2005) += tsc2005.o
>  obj-$(CONFIG_TOUCHSCREEN_TSC2007) += tsc2007.o
> diff --git a/drivers/input/touchscreen/ts4800-ts.c b/drivers/input/touchscreen/ts4800-ts.c
> new file mode 100644
> index 0000000..1e81b17
> --- /dev/null
> +++ b/drivers/input/touchscreen/ts4800-ts.c
> @@ -0,0 +1,238 @@
> +/*
> + * Touchscreen driver for the TS-4800 board
> + *
> + * Copyright (c) 2015 - Savoir-faire Linux
> + *
> + * This file is licensed under the terms of the GNU General Public
> + * License version 2. This program is licensed "as is" without any
> + * warranty of any kind, whether express or implied.
> + */
> +
> +#include <linux/input.h>
> +#include <linux/input-polldev.h>
> +#include <linux/io.h>
> +#include <linux/kernel.h>
> +#include <linux/mfd/syscon.h>
> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/platform_device.h>
> +#include <linux/regmap.h>
> +
> +/* polling interval in ms*/
> +#define POLL_INTERVAL           3
> +
> +/* sensor values are 12-bit wide */
> +#define MAX_12BIT               ((1 << 12) - 1)
> +
> +#define PENDOWN_MASK            0x1
> +
> +#define X_OFFSET                0x0
> +#define Y_OFFSET                0x2
> +
> +struct ts4800_ts {
> + struct input_polled_dev *poll_dev;
> + struct device           *dev;
> + char                    phys[32];
> +
> + void __iomem            *base;
> + struct regmap           *regmap;
> + unsigned int            reg;
> + unsigned int            bit;
> +
> + bool                    pendown;
> + int                     debounce;
> +};
> +
> +static void ts4800_ts_open(struct input_polled_dev *dev)
> +{
> + struct ts4800_ts *ts = dev->private;
> + int ret;
> +
> + ret = regmap_update_bits(ts->regmap, ts->reg,
> + 1 << ts->bit, 1  << ts->bit);

Instead of doing shift every time you can store already shifted value in
ts->bit.

> + if (ret)
> + dev_warn(ts->dev, "Failed to enable touchscreen\n");
> +}
> +
> +static void ts4800_ts_close(struct input_polled_dev *dev)
> +{
> + struct ts4800_ts *ts = dev->private;
> + int ret;
> +
> + ret = regmap_update_bits(ts->regmap, ts->reg,
> + 1 << ts->bit, 0);
> + if (ret)
> + dev_warn(ts->dev, "Failed to disable touchscreen\n");
> +
> +}
> +
> +static void ts4800_ts_poll(struct input_polled_dev *dev)
> +{
> + struct input_dev *input_dev = dev->input;
> + struct ts4800_ts *ts = dev->private;
> + u16 last_x = readw(ts->base + X_OFFSET);
> + u16 last_y = readw(ts->base + Y_OFFSET);
> + bool pendown = last_x & PENDOWN_MASK;
> +
> + if (!pendown && ts->pendown) {
> + ts->pendown = false;
> + ts->debounce = 1;
> + input_report_key(input_dev, BTN_TOUCH, 0);
> + input_sync(input_dev);
> + }
> +
> + if (pendown) {
> + if (ts->debounce) {
> + ts->debounce = 0;

This looks like a boolean, but I think having a counter for debounce is
more natural.

> + return;
> + }
> +
> + if (!ts->pendown) {
> + input_report_key(input_dev, BTN_TOUCH, 1);
> + ts->pendown = true;
> + }
> +
> + last_x = ((~last_x) >> 4) & MAX_12BIT;
> + last_y = ((~last_y) >> 4) & MAX_12BIT;
> +
> + input_report_abs(input_dev, ABS_X, last_x);
> + input_report_abs(input_dev, ABS_Y, last_y);
> + input_sync(input_dev);
> + }
> +}
> +
> +static void ts4800_input_setup(struct input_dev *input_dev)
> +{
> + input_dev->evbit[0] = BIT_MASK(EV_KEY) | BIT_MASK(EV_ABS);
> + input_dev->keybit[BIT_WORD(BTN_TOUCH)] = BIT_MASK(BTN_TOUCH);
> +
> + input_set_abs_params(input_dev, ABS_X, 0, MAX_12BIT, 0, 0);
> + input_set_abs_params(input_dev, ABS_Y, 0, MAX_12BIT, 0, 0);
> +}
> +
> +static int ts4800_parse_dt(struct platform_device *pdev,
> +   struct ts4800_ts *ts)
> +{
> + struct device *dev = &pdev->dev;
> + struct device_node *np = dev->of_node;
> + struct device_node *syscon_np;
> + struct resource *res;
> + u32 reg, bit;
> + int ret;
> +
> + res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> + ts->base = devm_ioremap_resource(dev, res);
> + if (IS_ERR(ts->base))
> + return PTR_ERR(ts->base);

This has nothing to do with DT parsing, I'd move it out into probe().

> +
> + syscon_np = of_parse_phandle(np, "syscon", 0);
> + if (!syscon_np) {
> + dev_err(dev, "no syscon property\n");
> + return -ENODEV;
> + }
> +
> + ret = of_property_read_u32_index(np, "syscon", 1, &reg);
> + if (ret < 0) {
> + dev_err(dev, "no offset in syscon\n");
> + return ret;
> + }
> +
> + ret = of_property_read_u32_index(np, "syscon", 2, &bit);
> + if (ret < 0) {
> + dev_err(dev, "no bit in syscon\n");
> + return ret;
> + }
> +
> + ts->reg = reg;
> + ts->bit = bit;
> + ts->regmap = syscon_node_to_regmap(syscon_np);
> +
> + if (IS_ERR(ts->regmap)) {
> + dev_err(dev, "cannot get parent's regmap\n");
> + return PTR_ERR(ts->regmap);
> + }
> +
> + return 0;
> +}
> +
> +static int ts4800_ts_probe(struct platform_device *pdev)
> +{
> + struct input_polled_dev *poll_dev;
> + struct input_dev *input_dev;
> + struct ts4800_ts *ts;
> + int ret;
> +
> + ts = devm_kzalloc(&pdev->dev, sizeof(struct ts4800_ts), GFP_KERNEL);
> + if (!ts)
> + return -ENOMEM;
> +
> + ret = ts4800_parse_dt(pdev, ts);
> + if (ret)
> + return ret;
> +
> + poll_dev = devm_input_allocate_polled_device(&pdev->dev);
> + if (!poll_dev)
> + return -ENOMEM;
> +
> + snprintf(ts->phys, sizeof(ts->phys), "%s/input0", dev_name(&pdev->dev));
> + ts->poll_dev = poll_dev;
> + ts->dev = &pdev->dev;
> + ts->pendown = false;
> + ts->debounce = 1;
> +
> + poll_dev->private = ts;
> + poll_dev->poll_interval = POLL_INTERVAL;
> + poll_dev->open = ts4800_ts_open;
> + poll_dev->close = ts4800_ts_close;
> + poll_dev->poll = ts4800_ts_poll;
> +
> + ts4800_input_setup(poll_dev->input);
> +
> + input_dev = poll_dev->input;
> + input_dev->name = "TS-4800 Touchscreen";
> + input_dev->phys = ts->phys;
> + input_dev->dev.parent = pdev->dev.parent;

This is wrong. First of all managed input device requires that you do
not override parent (see comment to devm_input_allocate_polled_device)
and also naturally this input dveice's parent is this platform device,
and parent of platform device is input dveice's grandparent.

> +
> + ret = input_register_polled_device(poll_dev);
> + if (ret) {
> + dev_err(&pdev->dev,
> + "Unabled to register polled input device (%d)\n",
> + ret);
> + return ret;
> + }
> +
> + platform_set_drvdata(pdev, ts);
> +
> + return 0;
> +}
> +
> +static int ts4800_ts_remove(struct platform_device *pdev)
> +{
> + struct ts4800_ts *ts = platform_get_drvdata(pdev);
> + struct input_polled_dev *poll_dev = ts->poll_dev;
> +
> + input_unregister_polled_device(poll_dev);

Since you are using managed polled device you do not need to explicitly
unregister it.

> +
> + return 0;
> +}
> +
> +static const struct of_device_id ts4800_ts_of_match[] = {
> + { .compatible = "technologic,ts4800-ts", },
> + { },
> +};
> +MODULE_DEVICE_TABLE(of, ts4800_ts_of_match);
> +
> +static struct platform_driver ts4800_ts_driver = {
> + .driver = {
> + .name = "ts4800-ts",
> + .of_match_table = ts4800_ts_of_match,
> + },
> + .probe = ts4800_ts_probe,
> + .remove = ts4800_ts_remove,
> +};
> +module_platform_driver(ts4800_ts_driver);
> +
> +MODULE_AUTHOR("Damien Riegel <damien.riegel-4ysUXcep3aM1wj+D4I0NRVaTQe2KTcn/@public.gmane.org>");
> +MODULE_DESCRIPTION("TS-4800 Touchscreen Driver");
> +MODULE_LICENSE("GPL v2");
> +MODULE_ALIAS("platform:ts4800_ts");
> --
> 2.5.0
>

I adjusted the aforementioned items and applied the driver, please check
out my "next" branch.

Thanks.

-- 
Dmitry
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