| Message ID | 1523350677-27106-9-git-send-email-eugen.hristev@microchip.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
Hi Eugen, On Tue, Apr 10, 2018 at 11:57:54AM +0300, Eugen Hristev 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> > --- > 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 | 200 ++++++++++++++++++++++++ > 3 files changed, 214 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 > 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 resistive-adc-touch.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..843c7f9 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-$(CONFIG_TOUCHSCREEN_ADC) += resistive-adc-touch.o > obj-$(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/resistive-adc-touch.c b/drivers/input/touchscreen/resistive-adc-touch.c > new file mode 100644 > index 0000000..7e201ee > --- /dev/null > +++ b/drivers/input/touchscreen/resistive-adc-touch.c > @@ -0,0 +1,200 @@ > +// 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/input/touchscreen.h> > +#include <linux/iio/consumer.h> > +#include <linux/iio/iio.h> > +#include <linux/module.h> > +#include <linux/of.h> > +#include <linux/of_device.h> > +#include <linux/platform_device.h> > + > +#define DRIVER_NAME "resistive-adc-touch" > +#define GRTS_DEFAULT_PRESSURE_THRESHOLD 50000 > +#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 > + * @prop: touchscreen properties struct > + */ > +struct grts_state { > + u32 pressure_threshold; > + bool pressure; > + struct iio_channel *iio_chans; > + struct iio_cb_buffer *iio_cb; > + struct input_dev *input; > + struct touchscreen_properties prop; > +}; > + > +static int grts_cb(const void *data, void *private) > +{ > + const u16 *touch_info = data; > + struct grts_state *st = private; > + Extra blank line. > + unsigned int x, y, press = 0xFFFF; Why to you need to initialize "press"? > + > + /* 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 */ Hm, so this makes "press" not pressure but resistance... > + input_report_key(st->input, BTN_TOUCH, 0); > + input_sync(st->input); > + return 0; > + } > + > + /* report proper touch to subsystem*/ > + touchscreen_report_pos(st->input, &st->prop, x, y, false); > + if (st->pressure) > + input_report_abs(st->input, ABS_PRESSURE, press); and if this is resistance, then you want to have: input_report_abs(st->input, ABS_PRESSURE, st->resistance_threshold - resistance); > + input_report_key(st->input, BTN_TOUCH, 1); > + input_sync(st->input); > + > + return 0; > +} > + > +static int grts_open(struct input_dev *dev) > +{ > + int error; > + struct grts_state *st = input_get_drvdata(dev); > + > + error = iio_channel_start_all_cb(st->iio_cb); > + if (error) { > + dev_err(dev->dev.parent, "failed to start callback buffer.\n"); > + return 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 void grts_disable(void *data) > +{ > + iio_channel_release_all_cb(data); > +} > + > +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; Let's call this variable "error". There is also no need to initialize it to 0. > + > + st = devm_kzalloc(dev, sizeof(struct grts_state), GFP_KERNEL); > + if (!st) > + return -ENOMEM; > + > + ret = of_property_read_u32(node, "touchscreen-threshold-pressure", > + &st->pressure_threshold); Let's use generic device property API (device_property_read_u32). > + if (ret < 0) { I do not think of_ or device_ property API returns positive on success. So simply 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); > + Extra blank line. > + 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, 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); I am sure we can figure the range given the resistance threshold. > + > + input->evbit[0] = BIT_MASK(EV_KEY) | BIT_MASK(EV_ABS); > + input->keybit[BIT_WORD(BTN_TOUCH)] = BIT_MASK(BTN_TOUCH); Replace this 2 with 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); > + > + 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(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; > + } > + > + ret = devm_add_action_or_reset(dev, grts_disable, st->iio_cb); if (error) return error; > + > + platform_set_drvdata(pdev, st); I do not think you are using platform device driver data anywhere. > + > + return ret; Prefer explicit success returns, so return 0; > +} > + > +static const struct of_device_id grts_of_match[] = { > + { > + .compatible = "resistive-adc-touch", > + }, { > + /* sentinel */ > + }, > +}; > + > +MODULE_DEVICE_TABLE(of, grts_of_match); > + > +static struct platform_driver grts_driver = { > + .probe = grts_probe, > + .driver = { > + .name = DRIVER_NAME, Keep indenting with tabs please. > + .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"); > -- > 2.7.4 >
On Mon, Apr 23, 2018 at 04:22:51PM -0700, Dmitry Torokhov wrote: > Hi Eugen, > > On Tue, Apr 10, 2018 at 11:57:54AM +0300, Eugen Hristev 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> > > --- > > 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 | 200 ++++++++++++++++++++++++ > > 3 files changed, 214 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 > > 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 resistive-adc-touch.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..843c7f9 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-$(CONFIG_TOUCHSCREEN_ADC) += resistive-adc-touch.o > > obj-$(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/resistive-adc-touch.c b/drivers/input/touchscreen/resistive-adc-touch.c > > new file mode 100644 > > index 0000000..7e201ee > > --- /dev/null > > +++ b/drivers/input/touchscreen/resistive-adc-touch.c > > @@ -0,0 +1,200 @@ > > +// 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/input/touchscreen.h> > > +#include <linux/iio/consumer.h> > > +#include <linux/iio/iio.h> > > +#include <linux/module.h> > > +#include <linux/of.h> > > +#include <linux/of_device.h> > > +#include <linux/platform_device.h> > > + > > +#define DRIVER_NAME "resistive-adc-touch" > > +#define GRTS_DEFAULT_PRESSURE_THRESHOLD 50000 > > +#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 > > + * @prop: touchscreen properties struct > > + */ > > +struct grts_state { > > + u32 pressure_threshold; > > + bool pressure; > > + struct iio_channel *iio_chans; > > + struct iio_cb_buffer *iio_cb; > > + struct input_dev *input; > > + struct touchscreen_properties prop; > > +}; > > + > > +static int grts_cb(const void *data, void *private) > > +{ > > + const u16 *touch_info = data; > > + struct grts_state *st = private; > > + > > Extra blank line. > > > + unsigned int x, y, press = 0xFFFF; > > Why to you need to initialize "press"? > > > + > > + /* 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 */ > > Hm, so this makes "press" not pressure but resistance... Sorry, ignore this and below. I misread the code. > > > + input_report_key(st->input, BTN_TOUCH, 0); > > + input_sync(st->input); > > + return 0; > > + } > > + > > + /* report proper touch to subsystem*/ > > + touchscreen_report_pos(st->input, &st->prop, x, y, false); > > + if (st->pressure) > > + input_report_abs(st->input, ABS_PRESSURE, press); > > and if this is resistance, then you want to have: > > input_report_abs(st->input, ABS_PRESSURE, > st->resistance_threshold - resistance); > > > + input_report_key(st->input, BTN_TOUCH, 1); > > + input_sync(st->input); > > + > > + return 0; > > +} > > + > > +static int grts_open(struct input_dev *dev) > > +{ > > + int error; > > + struct grts_state *st = input_get_drvdata(dev); > > + > > + error = iio_channel_start_all_cb(st->iio_cb); > > + if (error) { > > + dev_err(dev->dev.parent, "failed to start callback buffer.\n"); > > + return 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 void grts_disable(void *data) > > +{ > > + iio_channel_release_all_cb(data); > > +} > > + > > +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; > > Let's call this variable "error". There is also no need to initialize it > to 0. > > > + > > + st = devm_kzalloc(dev, sizeof(struct grts_state), GFP_KERNEL); > > + if (!st) > > + return -ENOMEM; > > + > > + ret = of_property_read_u32(node, "touchscreen-threshold-pressure", > > + &st->pressure_threshold); > > Let's use generic device property API (device_property_read_u32). > > > > + if (ret < 0) { > > I do not think of_ or device_ property API returns positive on success. > So simply > > 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); > > + > > Extra blank line. > > > + 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, 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); > > I am sure we can figure the range given the resistance threshold. > > > + > > + input->evbit[0] = BIT_MASK(EV_KEY) | BIT_MASK(EV_ABS); > > + input->keybit[BIT_WORD(BTN_TOUCH)] = BIT_MASK(BTN_TOUCH); > > Replace this 2 with > > 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); > > + > > + 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(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; > > + } > > + > > + ret = devm_add_action_or_reset(dev, grts_disable, st->iio_cb); > > if (error) > return error; > > > + > > + platform_set_drvdata(pdev, st); > > I do not think you are using platform device driver data anywhere. > > > + > > + return ret; > > Prefer explicit success returns, so > > return 0; > > > +} > > + > > +static const struct of_device_id grts_of_match[] = { > > + { > > + .compatible = "resistive-adc-touch", > > + }, { > > + /* sentinel */ > > + }, > > +}; > > + > > +MODULE_DEVICE_TABLE(of, grts_of_match); > > + > > +static struct platform_driver grts_driver = { > > + .probe = grts_probe, > > + .driver = { > > + .name = DRIVER_NAME, > > Keep indenting with tabs please. > > > + .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"); > > -- > > 2.7.4 > > > > -- > Dmitry
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 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 resistive-adc-touch.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..843c7f9 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-$(CONFIG_TOUCHSCREEN_ADC) += resistive-adc-touch.o obj-$(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/resistive-adc-touch.c b/drivers/input/touchscreen/resistive-adc-touch.c new file mode 100644 index 0000000..7e201ee --- /dev/null +++ b/drivers/input/touchscreen/resistive-adc-touch.c @@ -0,0 +1,200 @@ +// 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/input/touchscreen.h> +#include <linux/iio/consumer.h> +#include <linux/iio/iio.h> +#include <linux/module.h> +#include <linux/of.h> +#include <linux/of_device.h> +#include <linux/platform_device.h> + +#define DRIVER_NAME "resistive-adc-touch" +#define GRTS_DEFAULT_PRESSURE_THRESHOLD 50000 +#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 + * @prop: touchscreen properties struct + */ +struct grts_state { + u32 pressure_threshold; + bool pressure; + struct iio_channel *iio_chans; + struct iio_cb_buffer *iio_cb; + struct input_dev *input; + struct touchscreen_properties prop; +}; + +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*/ + touchscreen_report_pos(st->input, &st->prop, x, y, false); + 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 error; + struct grts_state *st = input_get_drvdata(dev); + + error = iio_channel_start_all_cb(st->iio_cb); + if (error) { + dev_err(dev->dev.parent, "failed to start callback buffer.\n"); + return 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 void grts_disable(void *data) +{ + iio_channel_release_all_cb(data); +} + +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, "touchscreen-threshold-pressure", + &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->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); + + /* parse optional device tree properties */ + touchscreen_parse_properties(input, false, &st->prop); + + 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(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; + } + + ret = devm_add_action_or_reset(dev, grts_disable, st->iio_cb); + + platform_set_drvdata(pdev, st); + + return ret; +} + +static const struct of_device_id grts_of_match[] = { + { + .compatible = "resistive-adc-touch", + }, { + /* sentinel */ + }, +}; + +MODULE_DEVICE_TABLE(of, grts_of_match); + +static struct platform_driver grts_driver = { + .probe = grts_probe, + .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 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 | 200 ++++++++++++++++++++++++ 3 files changed, 214 insertions(+) create mode 100644 drivers/input/touchscreen/resistive-adc-touch.c