| Message ID | 1522153963-1121-8-git-send-email-eugen.hristev@microchip.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Tue, 27 Mar 2018 15:32:40 +0300 Eugen Hristev <eugen.hristev@microchip.com> 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@microchip.com> I like this a lot! A few minor bits and bobs inline. Over to Dmitry for the input side of things. Jonathan > --- > 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/touch_adc.c | 199 ++++++++++++++++++++++++++++++++++ > 3 files changed, 213 insertions(+) > create mode 100644 drivers/input/touchscreen/touch_adc.c > > diff --git a/drivers/input/touchscreen/Kconfig b/drivers/input/touchscreen/Kconfig > index 4f15496..afd879f 100644 > --- a/drivers/input/touchscreen/Kconfig > +++ b/drivers/input/touchscreen/Kconfig > @@ -92,6 +92,19 @@ config TOUCHSCREEN_AD7879_SPI > To compile this driver as a module, choose M here: the > module will be called ad7879-spi. > > +config TOUCHSCREEN_ADC > + tristate "Generic ADC based resistive touchscreen" > + depends on IIO > + select IIO_BUFFER_CB > + help > + Say Y here if you want to use the generic ADC > + resistive touchscreen driver. > + > + If unsure, say N (but it's safe to say "Y"). > + > + To compile this driver as a module, choose M here: the > + module will be called touch_adc.ko. > + > config TOUCHSCREEN_AR1021_I2C > tristate "Microchip AR1020/1021 i2c touchscreen" > depends on I2C && OF > diff --git a/drivers/input/touchscreen/Makefile b/drivers/input/touchscreen/Makefile > index dddae79..cbe6121 100644 > --- a/drivers/input/touchscreen/Makefile > +++ b/drivers/input/touchscreen/Makefile > @@ -13,6 +13,7 @@ obj-$(CONFIG_TOUCHSCREEN_AD7877) += ad7877.o > obj-$(CONFIG_TOUCHSCREEN_AD7879) += ad7879.o > obj-$(CONFIG_TOUCHSCREEN_AD7879_I2C) += ad7879-i2c.o > obj-$(CONFIG_TOUCHSCREEN_AD7879_SPI) += ad7879-spi.o > +obj-$(CONFIG_TOUCHSCREEN_ADC) += touch_adc.o > obj-$(CONFIG_TOUCHSCREEN_ADS7846) += ads7846.o > obj-$(CONFIG_TOUCHSCREEN_AR1021_I2C) += ar1021_i2c.o > obj-$(CONFIG_TOUCHSCREEN_ATMEL_MXT) += atmel_mxt_ts.o > diff --git a/drivers/input/touchscreen/touch_adc.c b/drivers/input/touchscreen/touch_adc.c > new file mode 100644 > index 0000000..de4b929 > --- /dev/null > +++ b/drivers/input/touchscreen/touch_adc.c > @@ -0,0 +1,199 @@ > +// SPDX-License-Identifier: GPL-2.0 > +/* > + * ADC generic resistive touchscreen (GRTS) > + * > + * Copyright (C) 2017,2018 Microchip Technology, > + * Author: Eugen Hristev <eugen.hristev@microchip.com> > + * > + */ > +#include <linux/input.h> > +#include <linux/of.h> > +#include <linux/of_device.h> > +#include <linux/platform_device.h> > +#include <linux/iio/consumer.h> > +#include <linux/iio/iio.h> > +#include <linux/module.h> > + > +#define DRIVER_NAME "touch_adc" > +#define GRTS_DEFAULT_PRESSURE_THRESHOLD 10000 > +#define MAX_POS_MASK GENMASK(11, 0) > + > +/** > + * grts_state - generic resistive touch screen information struct > + * @pressure_threshold: number representing the threshold for the pressure > + * @pressure: are we getting pressure info or not > + * @iio_chans: list of channels acquired > + * @iio_cb: iio_callback buffer for the data > + * @input: the input device structure that we register > + */ > +struct grts_state { > + u32 pressure_threshold; > + bool pressure; > + struct iio_channel *iio_chans; > + struct iio_cb_buffer *iio_cb; > + struct input_dev *input; > +}; > + > +static int grts_cb(const void *data, void *private) > +{ > + const u16 *touch_info = data; > + struct grts_state *st = private; > + > + unsigned int x, y, press = 0xFFFF; > + > + /* channel data coming in buffer in the order below */ > + x = touch_info[0]; > + y = touch_info[1]; > + if (st->pressure) > + press = touch_info[2]; > + > + if ((!x && !y) || (st->pressure && (press > st->pressure_threshold))) { Ah, clearly pressure is the other way around to I assumed and gets larger as the pressure is reduced. hmm. > + /* report end of touch */ > + input_report_key(st->input, BTN_TOUCH, 0); > + input_sync(st->input); > + return 0; > + } > + > + /* report proper touch to subsystem*/ > + input_report_abs(st->input, ABS_X, x); > + input_report_abs(st->input, ABS_Y, y); > + if (st->pressure) > + input_report_abs(st->input, ABS_PRESSURE, press); > + input_report_key(st->input, BTN_TOUCH, 1); > + input_sync(st->input); blank line preferred here. > + return 0; > +} > + > +static int grts_open(struct input_dev *dev) > +{ > + int ret; > + struct grts_state *st = input_get_drvdata(dev); > + > + ret = iio_channel_start_all_cb(st->iio_cb); > + if (ret) { > + dev_err(dev->dev.parent, "failed to start callback buffer.\n"); > + return ret; Drop the return ret out of the brackets. > + } > + return 0; > +} > + > +static void grts_close(struct input_dev *dev) > +{ > + struct grts_state *st = input_get_drvdata(dev); > + > + iio_channel_stop_all_cb(st->iio_cb); > +} > + > +static int grts_probe(struct platform_device *pdev) > +{ > + struct grts_state *st; > + struct input_dev *input; > + struct device *dev = &pdev->dev; > + struct device_node *node = dev->of_node; > + struct iio_channel *chan; > + int ret = 0; > + > + st = devm_kzalloc(dev, sizeof(struct grts_state), GFP_KERNEL); > + if (!st) > + return -ENOMEM; > + > + ret = of_property_read_u32(node, > + "generic-adc-resistive-touchscreen,pressure-threshold", > + &st->pressure_threshold); > + if (ret < 0) { > + 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->dev.parent = dev; > + input->open = grts_open; > + input->close = grts_close; > + > + input_set_abs_params(input, ABS_X, 0, MAX_POS_MASK - 1, 0, 0); > + input_set_abs_params(input, ABS_Y, 0, MAX_POS_MASK - 1, 0, 0); > + if (st->pressure) > + input_set_abs_params(input, ABS_PRESSURE, 0, 0xffffff, 0, 0); > + > + input->evbit[0] = BIT_MASK(EV_KEY) | BIT_MASK(EV_ABS); > + input->keybit[BIT_WORD(BTN_TOUCH)] = BIT_MASK(BTN_TOUCH); > + > + st->input = input; > + input_set_drvdata(input, st); > + > + ret = input_register_device(input); > + if (ret) { > + dev_err(dev, "failed to register input device."); > + return ret; > + } > + > + st->iio_cb = iio_channel_get_all_cb(&pdev->dev, grts_cb, st); > + > + if (IS_ERR(st->iio_cb)) { > + dev_err(dev, "failed to allocate callback buffer.\n"); > + ret = PTR_ERR(st->iio_cb); > + return ret; > + } > + > + platform_set_drvdata(pdev, st); > + > + return ret; > +} > + > +static int grts_remove(struct platform_device *pdev) > +{ > + struct grts_state *st = platform_get_drvdata(pdev); > + > + iio_channel_release_all_cb(st->iio_cb); > + input_unregister_device(st->input); blank line preferred before simple returns. > + return 0; > +} > + > +static const struct of_device_id grts_of_match[] = { > + { > + .compatible = "generic-resistive-adc-touch", > + }, { > + /* sentinel */ > + }, > +}; > + > +MODULE_DEVICE_TABLE(of, grts_of_match); > + > +static struct platform_driver grts_driver = { > + .probe = grts_probe, > + .remove = grts_remove, > + .driver = { > + .name = DRIVER_NAME, > + .of_match_table = of_match_ptr(grts_of_match), > + }, > +}; > + > +module_platform_driver(grts_driver); > + > +MODULE_AUTHOR("Eugen Hristev <eugen.hristev@microchip.com>"); > +MODULE_DESCRIPTION("Generic ADC Resistive Touch Driver"); > +MODULE_LICENSE("GPL v2"); -- To unsubscribe from this list: send the line "unsubscribe linux-iio" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Fri, Mar 30, 2018 at 01:58:35PM +0100, Jonathan Cameron wrote: > On Tue, 27 Mar 2018 15:32:40 +0300 > Eugen Hristev <eugen.hristev@microchip.com> 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@microchip.com> > I like this a lot! > > A few minor bits and bobs inline. Over to Dmitry for the input > side of things. > > Jonathan > > > --- > > 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/touch_adc.c | 199 ++++++++++++++++++++++++++++++++++ > > 3 files changed, 213 insertions(+) > > create mode 100644 drivers/input/touchscreen/touch_adc.c > > > > diff --git a/drivers/input/touchscreen/Kconfig b/drivers/input/touchscreen/Kconfig > > index 4f15496..afd879f 100644 > > --- a/drivers/input/touchscreen/Kconfig > > +++ b/drivers/input/touchscreen/Kconfig > > @@ -92,6 +92,19 @@ config TOUCHSCREEN_AD7879_SPI > > To compile this driver as a module, choose M here: the > > module will be called ad7879-spi. > > > > +config TOUCHSCREEN_ADC > > + tristate "Generic ADC based resistive touchscreen" > > + depends on IIO > > + select IIO_BUFFER_CB > > + help > > + Say Y here if you want to use the generic ADC > > + resistive touchscreen driver. > > + > > + If unsure, say N (but it's safe to say "Y"). > > + > > + To compile this driver as a module, choose M here: the > > + module will be called touch_adc.ko. > > + > > config TOUCHSCREEN_AR1021_I2C > > tristate "Microchip AR1020/1021 i2c touchscreen" > > depends on I2C && OF > > diff --git a/drivers/input/touchscreen/Makefile b/drivers/input/touchscreen/Makefile > > index dddae79..cbe6121 100644 > > --- a/drivers/input/touchscreen/Makefile > > +++ b/drivers/input/touchscreen/Makefile > > @@ -13,6 +13,7 @@ obj-$(CONFIG_TOUCHSCREEN_AD7877) += ad7877.o > > obj-$(CONFIG_TOUCHSCREEN_AD7879) += ad7879.o > > obj-$(CONFIG_TOUCHSCREEN_AD7879_I2C) += ad7879-i2c.o > > obj-$(CONFIG_TOUCHSCREEN_AD7879_SPI) += ad7879-spi.o > > +obj-$(CONFIG_TOUCHSCREEN_ADC) += touch_adc.o > > obj-$(CONFIG_TOUCHSCREEN_ADS7846) += ads7846.o > > obj-$(CONFIG_TOUCHSCREEN_AR1021_I2C) += ar1021_i2c.o > > obj-$(CONFIG_TOUCHSCREEN_ATMEL_MXT) += atmel_mxt_ts.o > > diff --git a/drivers/input/touchscreen/touch_adc.c b/drivers/input/touchscreen/touch_adc.c > > new file mode 100644 > > index 0000000..de4b929 > > --- /dev/null > > +++ b/drivers/input/touchscreen/touch_adc.c > > @@ -0,0 +1,199 @@ > > +// SPDX-License-Identifier: GPL-2.0 > > +/* > > + * ADC generic resistive touchscreen (GRTS) > > + * > > + * Copyright (C) 2017,2018 Microchip Technology, > > + * Author: Eugen Hristev <eugen.hristev@microchip.com> > > + * > > + */ > > +#include <linux/input.h> > > +#include <linux/of.h> > > +#include <linux/of_device.h> > > +#include <linux/platform_device.h> > > +#include <linux/iio/consumer.h> > > +#include <linux/iio/iio.h> > > +#include <linux/module.h> > > + > > +#define DRIVER_NAME "touch_adc" > > +#define GRTS_DEFAULT_PRESSURE_THRESHOLD 10000 > > +#define MAX_POS_MASK GENMASK(11, 0) > > + > > +/** > > + * grts_state - generic resistive touch screen information struct > > + * @pressure_threshold: number representing the threshold for the pressure > > + * @pressure: are we getting pressure info or not > > + * @iio_chans: list of channels acquired > > + * @iio_cb: iio_callback buffer for the data > > + * @input: the input device structure that we register > > + */ > > +struct grts_state { > > + u32 pressure_threshold; > > + bool pressure; > > + struct iio_channel *iio_chans; > > + struct iio_cb_buffer *iio_cb; > > + struct input_dev *input; > > +}; > > + > > +static int grts_cb(const void *data, void *private) > > +{ > > + const u16 *touch_info = data; > > + struct grts_state *st = private; > > + > > + unsigned int x, y, press = 0xFFFF; > > + > > + /* channel data coming in buffer in the order below */ > > + x = touch_info[0]; > > + y = touch_info[1]; > > + if (st->pressure) > > + press = touch_info[2]; > > + > > + if ((!x && !y) || (st->pressure && (press > st->pressure_threshold))) { > Ah, clearly pressure is the other way around to I assumed and gets larger as > the pressure is reduced. hmm. OK, in this case it should not be reported directly as ABS_PRESSURE, as ABSP_RESSURE value is expected to grow the firmer the finger touches the surface, and reduce to 0 when finger is about to be lifted. > > > + /* report end of touch */ > > + input_report_key(st->input, BTN_TOUCH, 0); > > + input_sync(st->input); > > + return 0; > > + } > > + > > + /* report proper touch to subsystem*/ > > + input_report_abs(st->input, ABS_X, x); > > + input_report_abs(st->input, ABS_Y, y); > > + if (st->pressure) > > + input_report_abs(st->input, ABS_PRESSURE, press); > > + input_report_key(st->input, BTN_TOUCH, 1); > > + input_sync(st->input); > blank line preferred here. > > > + return 0; > > +} > > + > > +static int grts_open(struct input_dev *dev) > > +{ > > + int ret; > > + struct grts_state *st = input_get_drvdata(dev); > > + > > + ret = iio_channel_start_all_cb(st->iio_cb); > > + if (ret) { > > + dev_err(dev->dev.parent, "failed to start callback buffer.\n"); > > + return ret; > Drop the return ret out of the brackets. Actually I prefer explicit "success" return path. But I would appreciate if we called this "ret" variable "error". > > > + } > > + return 0; > > +} > > + > > +static void grts_close(struct input_dev *dev) > > +{ > > + struct grts_state *st = input_get_drvdata(dev); > > + > > + iio_channel_stop_all_cb(st->iio_cb); > > +} > > + > > +static int grts_probe(struct platform_device *pdev) > > +{ > > + struct grts_state *st; > > + struct input_dev *input; > > + struct device *dev = &pdev->dev; > > + struct device_node *node = dev->of_node; > > + struct iio_channel *chan; > > + int ret = 0; > > + > > + st = devm_kzalloc(dev, sizeof(struct grts_state), GFP_KERNEL); > > + if (!st) > > + return -ENOMEM; > > + > > + ret = of_property_read_u32(node, > > + "generic-adc-resistive-touchscreen,pressure-threshold", > > + &st->pressure_threshold); > > + if (ret < 0) { > > + 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->dev.parent = dev; This is already being set by devm_input_allocate_device(). > > + input->open = grts_open; > > + input->close = grts_close; > > + > > + input_set_abs_params(input, ABS_X, 0, MAX_POS_MASK - 1, 0, 0); > > + input_set_abs_params(input, ABS_Y, 0, MAX_POS_MASK - 1, 0, 0); > > + if (st->pressure) > > + input_set_abs_params(input, ABS_PRESSURE, 0, 0xffffff, 0, 0); It would be good if you used the API from include/linux/input/touchscreen.h to parse standard touchscreen properties and implement sizing, flippign and rotation of the screen. > > + > > + input->evbit[0] = BIT_MASK(EV_KEY) | BIT_MASK(EV_ABS); > > + input->keybit[BIT_WORD(BTN_TOUCH)] = BIT_MASK(BTN_TOUCH); > > + > > + st->input = input; > > + input_set_drvdata(input, st); > > + > > + ret = input_register_device(input); > > + if (ret) { > > + dev_err(dev, "failed to register input device."); > > + return ret; > > + } > > + > > + st->iio_cb = iio_channel_get_all_cb(&pdev->dev, grts_cb, st); Hmm, we don't have devm-variant for this? Then you could use devm_add_action_or_reset() to add cleanup action and completely remove grts_remove(). > > + > > + if (IS_ERR(st->iio_cb)) { > > + dev_err(dev, "failed to allocate callback buffer.\n"); > > + ret = PTR_ERR(st->iio_cb); > > + return ret; > > + } > > + > > + platform_set_drvdata(pdev, st); > > + > > + return ret; > > +} > > + > > +static int grts_remove(struct platform_device *pdev) > > +{ > > + struct grts_state *st = platform_get_drvdata(pdev); > > + > > + iio_channel_release_all_cb(st->iio_cb); > > + input_unregister_device(st->input); This call is not needed since you are using managed input device. > blank line preferred before simple returns. > > > + return 0; > > +} > > + > > +static const struct of_device_id grts_of_match[] = { > > + { > > + .compatible = "generic-resistive-adc-touch", > > + }, { > > + /* sentinel */ > > + }, > > +}; > > + > > +MODULE_DEVICE_TABLE(of, grts_of_match); > > + > > +static struct platform_driver grts_driver = { > > + .probe = grts_probe, > > + .remove = grts_remove, > > + .driver = { > > + .name = DRIVER_NAME, > > + .of_match_table = of_match_ptr(grts_of_match), > > + }, > > +}; > > + > > +module_platform_driver(grts_driver); > > + > > +MODULE_AUTHOR("Eugen Hristev <eugen.hristev@microchip.com>"); > > +MODULE_DESCRIPTION("Generic ADC Resistive Touch Driver"); > > +MODULE_LICENSE("GPL v2"); > Thanks.
> > > + > > > + input->evbit[0] = BIT_MASK(EV_KEY) | BIT_MASK(EV_ABS); > > > + input->keybit[BIT_WORD(BTN_TOUCH)] = BIT_MASK(BTN_TOUCH); > > > + > > > + st->input = input; > > > + input_set_drvdata(input, st); > > > + > > > + ret = input_register_device(input); > > > + if (ret) { > > > + dev_err(dev, "failed to register input device."); > > > + return ret; > > > + } > > > + > > > + st->iio_cb = iio_channel_get_all_cb(&pdev->dev, grts_cb, st); > > Hmm, we don't have devm-variant for this? Then you could use > devm_add_action_or_reset() to add cleanup action and completely remove > grts_remove(). Not yet, but I'm not adverse to having one... -- To unsubscribe from this list: send the line "unsubscribe linux-iio" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/drivers/input/touchscreen/Kconfig b/drivers/input/touchscreen/Kconfig index 4f15496..afd879f 100644 --- a/drivers/input/touchscreen/Kconfig +++ b/drivers/input/touchscreen/Kconfig @@ -92,6 +92,19 @@ config TOUCHSCREEN_AD7879_SPI To compile this driver as a module, choose M here: the module will be called ad7879-spi. +config TOUCHSCREEN_ADC + tristate "Generic ADC based resistive touchscreen" + depends on IIO + select IIO_BUFFER_CB + help + Say Y here if you want to use the generic ADC + resistive touchscreen driver. + + If unsure, say N (but it's safe to say "Y"). + + To compile this driver as a module, choose M here: the + module will be called touch_adc.ko. + config TOUCHSCREEN_AR1021_I2C tristate "Microchip AR1020/1021 i2c touchscreen" depends on I2C && OF diff --git a/drivers/input/touchscreen/Makefile b/drivers/input/touchscreen/Makefile index dddae79..cbe6121 100644 --- a/drivers/input/touchscreen/Makefile +++ b/drivers/input/touchscreen/Makefile @@ -13,6 +13,7 @@ obj-$(CONFIG_TOUCHSCREEN_AD7877) += ad7877.o obj-$(CONFIG_TOUCHSCREEN_AD7879) += ad7879.o obj-$(CONFIG_TOUCHSCREEN_AD7879_I2C) += ad7879-i2c.o obj-$(CONFIG_TOUCHSCREEN_AD7879_SPI) += ad7879-spi.o +obj-$(CONFIG_TOUCHSCREEN_ADC) += touch_adc.o obj-$(CONFIG_TOUCHSCREEN_ADS7846) += ads7846.o obj-$(CONFIG_TOUCHSCREEN_AR1021_I2C) += ar1021_i2c.o obj-$(CONFIG_TOUCHSCREEN_ATMEL_MXT) += atmel_mxt_ts.o diff --git a/drivers/input/touchscreen/touch_adc.c b/drivers/input/touchscreen/touch_adc.c new file mode 100644 index 0000000..de4b929 --- /dev/null +++ b/drivers/input/touchscreen/touch_adc.c @@ -0,0 +1,199 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * ADC generic resistive touchscreen (GRTS) + * + * Copyright (C) 2017,2018 Microchip Technology, + * Author: Eugen Hristev <eugen.hristev@microchip.com> + * + */ +#include <linux/input.h> +#include <linux/of.h> +#include <linux/of_device.h> +#include <linux/platform_device.h> +#include <linux/iio/consumer.h> +#include <linux/iio/iio.h> +#include <linux/module.h> + +#define DRIVER_NAME "touch_adc" +#define GRTS_DEFAULT_PRESSURE_THRESHOLD 10000 +#define MAX_POS_MASK GENMASK(11, 0) + +/** + * grts_state - generic resistive touch screen information struct + * @pressure_threshold: number representing the threshold for the pressure + * @pressure: are we getting pressure info or not + * @iio_chans: list of channels acquired + * @iio_cb: iio_callback buffer for the data + * @input: the input device structure that we register + */ +struct grts_state { + u32 pressure_threshold; + bool pressure; + struct iio_channel *iio_chans; + struct iio_cb_buffer *iio_cb; + struct input_dev *input; +}; + +static int grts_cb(const void *data, void *private) +{ + const u16 *touch_info = data; + struct grts_state *st = private; + + unsigned int x, y, press = 0xFFFF; + + /* channel data coming in buffer in the order below */ + x = touch_info[0]; + y = touch_info[1]; + if (st->pressure) + press = touch_info[2]; + + if ((!x && !y) || (st->pressure && (press > st->pressure_threshold))) { + /* report end of touch */ + input_report_key(st->input, BTN_TOUCH, 0); + input_sync(st->input); + return 0; + } + + /* report proper touch to subsystem*/ + input_report_abs(st->input, ABS_X, x); + input_report_abs(st->input, ABS_Y, y); + if (st->pressure) + input_report_abs(st->input, ABS_PRESSURE, press); + input_report_key(st->input, BTN_TOUCH, 1); + input_sync(st->input); + return 0; +} + +static int grts_open(struct input_dev *dev) +{ + int ret; + struct grts_state *st = input_get_drvdata(dev); + + ret = iio_channel_start_all_cb(st->iio_cb); + if (ret) { + dev_err(dev->dev.parent, "failed to start callback buffer.\n"); + return ret; + } + return 0; +} + +static void grts_close(struct input_dev *dev) +{ + struct grts_state *st = input_get_drvdata(dev); + + iio_channel_stop_all_cb(st->iio_cb); +} + +static int grts_probe(struct platform_device *pdev) +{ + struct grts_state *st; + struct input_dev *input; + struct device *dev = &pdev->dev; + struct device_node *node = dev->of_node; + struct iio_channel *chan; + int ret = 0; + + st = devm_kzalloc(dev, sizeof(struct grts_state), GFP_KERNEL); + if (!st) + return -ENOMEM; + + ret = of_property_read_u32(node, + "generic-adc-resistive-touchscreen,pressure-threshold", + &st->pressure_threshold); + if (ret < 0) { + 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->dev.parent = dev; + input->open = grts_open; + input->close = grts_close; + + input_set_abs_params(input, ABS_X, 0, MAX_POS_MASK - 1, 0, 0); + input_set_abs_params(input, ABS_Y, 0, MAX_POS_MASK - 1, 0, 0); + if (st->pressure) + input_set_abs_params(input, ABS_PRESSURE, 0, 0xffffff, 0, 0); + + input->evbit[0] = BIT_MASK(EV_KEY) | BIT_MASK(EV_ABS); + input->keybit[BIT_WORD(BTN_TOUCH)] = BIT_MASK(BTN_TOUCH); + + st->input = input; + input_set_drvdata(input, st); + + ret = input_register_device(input); + if (ret) { + dev_err(dev, "failed to register input device."); + return ret; + } + + st->iio_cb = iio_channel_get_all_cb(&pdev->dev, grts_cb, st); + + if (IS_ERR(st->iio_cb)) { + dev_err(dev, "failed to allocate callback buffer.\n"); + ret = PTR_ERR(st->iio_cb); + return ret; + } + + platform_set_drvdata(pdev, st); + + return ret; +} + +static int grts_remove(struct platform_device *pdev) +{ + struct grts_state *st = platform_get_drvdata(pdev); + + iio_channel_release_all_cb(st->iio_cb); + input_unregister_device(st->input); + return 0; +} + +static const struct of_device_id grts_of_match[] = { + { + .compatible = "generic-resistive-adc-touch", + }, { + /* sentinel */ + }, +}; + +MODULE_DEVICE_TABLE(of, grts_of_match); + +static struct platform_driver grts_driver = { + .probe = grts_probe, + .remove = grts_remove, + .driver = { + .name = DRIVER_NAME, + .of_match_table = of_match_ptr(grts_of_match), + }, +}; + +module_platform_driver(grts_driver); + +MODULE_AUTHOR("Eugen Hristev <eugen.hristev@microchip.com>"); +MODULE_DESCRIPTION("Generic ADC Resistive Touch Driver"); +MODULE_LICENSE("GPL v2");
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@microchip.com> --- 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/touch_adc.c | 199 ++++++++++++++++++++++++++++++++++ 3 files changed, 213 insertions(+) create mode 100644 drivers/input/touchscreen/touch_adc.c