On Mon, 30 Apr 2018 13:32:12 +0300
Eugen Hristev <eugen.hristev@xxxxxxxxxxxxx> wrote:
> This adds a generic resistive touchscreen (GRTS) driver, which is based
> on an IIO device (an ADC). It must be connected to the channels of an ADC
> to receive touch data. Then it will feed the data into the input subsystem
> where it registers an input device.
> It uses an IIO callback buffer to register to the IIO device
>
> Some parts of this patch are based on initial original work by
> Mohamed Jamsheeth Hajanajubudeen and Bandaru Venkateswara Swamy
>
> Signed-off-by: Eugen Hristev <eugen.hristev@xxxxxxxxxxxxx>
> ---
> Changes in v4:
> - added a small description in file header
> - changed MAX_POS_MASK to GRTS_MAX_POS_MASK
> - initialized press with 0, as this value means no touch.
> press has to be initialized because compiler/checkpatch complains
> that can be used uninitialized.
> - changed of_property_read_u32 to device_*
> - set_abs_params for pressure will have range according to threshold
> - changed evbit and keybit with set_capability call
> - changed variable names to error instead of ret
> - checked errors for add_action_or_reset
> - cosmetic cleaning
>
> Changes in v3:
> - pressure now reported naturally growing down-up
> - using helpers from touchscreen.h to parse DT properties
> - added devm_add_action_or_reset to handle callback buffer clean on exit
> - changed compatible and threshold property to adapt to changed bindings
>
> Changes in v2:
> - this is now a generic resistive adc touchscreen driver
>
> drivers/input/touchscreen/Kconfig | 13 ++
> drivers/input/touchscreen/Makefile | 1 +
> drivers/input/touchscreen/resistive-adc-touch.c | 199 ++++++++++++++++++++++++
> 3 files changed, 213 insertions(+)
> create mode 100644 drivers/input/touchscreen/resistive-adc-touch.c
>
> diff --git a/drivers/input/touchscreen/Kconfig b/drivers/input/touchscreen/Kconfig
> index 4f15496..8f85d3a 100644
> --- a/drivers/input/touchscreen/Kconfig
> +++ b/drivers/input/touchscreen/Kconfig
> @@ -92,6 +92,19 @@ config TOUCHSCREEN_AD7879_SPI
...
> +static int grts_probe(struct platform_device *pdev)
> +{
> + struct grts_state *st;
> + struct input_dev *input;
> + struct device *dev = &pdev->dev;
> + struct iio_channel *chan;
> + int error;
> +
> + st = devm_kzalloc(dev, sizeof(struct grts_state), GFP_KERNEL);
> + if (!st)
> + return -ENOMEM;
> +
> + error = device_property_read_u32(dev, "touchscreen-threshold-pressure",
> + &st->pressure_threshold);
> + if (error) {
> + dev_dbg(dev, "can't get touchscreen pressure threshold property.\n");
> + st->pressure_threshold = GRTS_DEFAULT_PRESSURE_THRESHOLD;
> + }
> +
> + /* get the channels from IIO device */
> + st->iio_chans = devm_iio_channel_get_all(dev);
> + if (IS_ERR(st->iio_chans)) {
> + if (PTR_ERR(st->iio_chans) != -EPROBE_DEFER)
> + dev_err(dev, "can't get iio channels.\n");
> + return PTR_ERR(st->iio_chans);
> + }
> +
> + chan = &st->iio_chans[0];
> + st->pressure = false;
> + while (chan && chan->indio_dev) {
> + if (!strcmp(chan->channel->datasheet_name, "pressure"))
> + st->pressure = true;
> + chan++;
> + }
> +
> + input = devm_input_allocate_device(dev);
> + if (!input) {
> + dev_err(dev, "failed to allocate input device.\n");
> + return -ENOMEM;
> + }
> +
> + input->name = DRIVER_NAME;
> + input->id.bustype = BUS_HOST;
> + input->open = grts_open;
> + input->close = grts_close;
> +
> + input_set_abs_params(input, ABS_X, 0, GRTS_MAX_POS_MASK - 1, 0, 0);
> + input_set_abs_params(input, ABS_Y, 0, GRTS_MAX_POS_MASK - 1, 0, 0);
> + if (st->pressure)
> + input_set_abs_params(input, ABS_PRESSURE,
> + st->pressure_threshold, 0xffff, 0, 0);
> +
> + input_set_capability(input, EV_KEY, BTN_TOUCH);
> +
> + /* parse optional device tree properties */
> + touchscreen_parse_properties(input, false, &st->prop);
> +
> + st->input = input;
> + input_set_drvdata(input, st);
> +
> + error = input_register_device(input);
> + if (error) {
> + dev_err(dev, "failed to register input device.");
> + return error;
> + }
> +
> + st->iio_cb = iio_channel_get_all_cb(dev, grts_cb, st);
> + if (IS_ERR(st->iio_cb)) {
> + dev_err(dev, "failed to allocate callback buffer.\n");
> + error = PTR_ERR(st->iio_cb);
> + return error;
> + }
> +
> + error = devm_add_action_or_reset(dev, grts_disable, st->iio_cb);
> + if (error)
> + dev_err(dev, "failed to add disable action.\n");
Why would you not be returning the error?
> +
> + return 0;
> +}
..
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