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

[Dmitry Torokhov]

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 
> ---
>  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 000..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 
> +#include 
> +#include 
> +#include 
> +#include 
> +#include 
> +#include 
> +#include 
> +#include 
> +
> +/* polling interval in ms*/
> +#define POLL_INTERVAL   3
> +
> +/* sensor values are 12-bit wide */
> +#define MAX_12BIT   ((1 << 12) - 1)
> +
> +#define PENDOWN_MASK0x1
> +
> +#define X_OFFSET0x0
> +#define Y_OFFSET0x2
> +
> +struct ts4800_ts {
> + struct input_polled_dev *poll_dev;
> + struct device   *dev;
> + charphys[32];
> +
> + void __iomem*base;
> + struct regmap   *regmap;
> + unsigned intreg;
> + unsigned intbit;
> +
> + boolpendown;
> + 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;
> + 

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

[Dmitry Torokhov]

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.

...

> +
> + poll_dev = devm_input_allocate_polled_device(>dev);
> + if (!poll_dev)
> + return -ENOMEM;

I wonder how useful touchscreen implemented as polling device is. Isn't
there an interrupt line for it?

Thanks.

-- 
Dmitry
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