Re: [PATCH v4 6/9] input: touchscreen: resistive-adc-touch: add generic resistive ADC touchscreen
From: Jonathan Cameron <jic23@kernel.org>
Date: 2018-05-06 17:33:50
Also in:
linux-arm-kernel, linux-devicetree, linux-iio, lkml
On Mon, 30 Apr 2018 13:32:12 +0300 Eugen Hristev [off-list ref] wrote:
quoted hunk ↗ jump to hunk
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 <redacted> --- 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.cdiff --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; +}
..