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authorLinus Torvalds <torvalds@linux-foundation.org>2026-08-23 13:28:57 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2026-08-23 13:28:57 -0700
commit4352b8aee98005853aa63f57d6377282de17a33f (patch)
tree27614d7a9ef05c32d089004e104364ce42324837 /drivers/input/touchscreen/resistive-adc-touch.c
downloadlinux-stable-4352b8aee98005853aa63f57d6377282de17a33f.tar.gz
linux-stable-4352b8aee98005853aa63f57d6377282de17a33f.zip
Merge tag 'i3c/for-7.3' of git://git.kernel.org/pub/scm/linux/kernel/git/i3c/linuxgrafted
Pull I3C updates from Alexandre Belloni: "A new driver this cycle, for the AMD AXI I3C controller. There are also new features such as IBI wakeup support, SETAASA device discovery and ACPI support for the the DAA methods, meaning we can now communicate with the SPD devices on DDR5 modules. New driver: - AMD AXI I3C master controller Subsystem: - I3C Common Command Code (CCC) handling improvements, especially around GET CCCs - SETAASA device discovery support - ACPI support for all existing DAA methods like SETDASA, SETNEWDA as well as I2C devices on I3C bus - IBI-based wakeup support Drivers: - dw: SETAASA support - mipi-i3c-hci: advertise IBI wakeup capability, AMD_PT I3C controller support, PIO queue management support for HCI v1.2 - renesas: improve suspend to RAM support, add runtime PM support" * tag 'i3c/for-7.3' of git://git.kernel.org/pub/scm/linux/kernel/git/i3c/linux: (70 commits) i3c: dw: reduce do_daa time if there's no client i3c: mipi-i3c-hci: Add support for AMD_PT I3C controller i3c: mipi-i3c-hci: Add PIO queue management support for HCI v1.2 i3c: mipi-i3c-hci: Fix missing STAT_IBI_STATUS_THLD in PIO mode i3c: dw: rename "pclk" to "apb" to match dt-binding i3c: dw: make struct dw_i3c_cmd smaller i3c: dw: use COMMAND_PORT_TRANSFER_ARG instead of hardcoding i3c: renesas: Don't register devices when ENTDAA times out i3c: master: dw-i3c-master: fix OD timing for first broadcast i3c: mipi-i3c-hci: Advertise IBI wakeup capability i3c: mipi-i3c-hci: Factor out i3c_hci_sysdev() i3c: mipi-i3c-hci-pci: Propagate I3C wakeup requirements to PCI i3c: master: Reject IBI requests from non-IBI-capable devices i3c: master: Add helper to query bus wakeup requirements i3c: master: Report wakeup events for IBIs i3c: master: Support IBI-based wakeup capability i3c: master: Fix potential UAF in i3c_device_match() i3c: master: Fix potential UAF in i3c_device_uevent() i3c: Make dev->desc locking assumptions explicit i3c: master: Fix use-after-free of master->this ...
Diffstat (limited to 'drivers/input/touchscreen/resistive-adc-touch.c')
-rw-r--r--drivers/input/touchscreen/resistive-adc-touch.c302
1 files changed, 302 insertions, 0 deletions
diff --git a/drivers/input/touchscreen/resistive-adc-touch.c b/drivers/input/touchscreen/resistive-adc-touch.c
new file mode 100644
index 000000000..68f7e2e28
--- /dev/null
+++ b/drivers/input/touchscreen/resistive-adc-touch.c
@@ -0,0 +1,302 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * ADC generic resistive touchscreen (GRTS)
+ * This is a generic input driver that connects to an ADC
+ * given the channels in device tree, and reports events to the input
+ * subsystem.
+ *
+ * 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/platform_device.h>
+#include <linux/property.h>
+
+#define DRIVER_NAME "resistive-adc-touch"
+#define GRTS_DEFAULT_PRESSURE_MIN 50000
+#define GRTS_DEFAULT_PRESSURE_MAX 65535
+#define GRTS_MAX_POS_MASK GENMASK(11, 0)
+#define GRTS_MAX_CHANNELS 4
+
+enum grts_ch_type {
+ GRTS_CH_X,
+ GRTS_CH_Y,
+ GRTS_CH_PRESSURE,
+ GRTS_CH_Z1,
+ GRTS_CH_Z2,
+ GRTS_CH_MAX = GRTS_CH_Z2 + 1
+};
+
+/**
+ * struct grts_state - generic resistive touch screen information struct
+ * @x_plate_ohms: resistance of the X plate
+ * @pressure_min: number representing the minimum 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
+ * @ch_map: map of channels that are defined for the touchscreen
+ */
+struct grts_state {
+ u32 x_plate_ohms;
+ u32 pressure_min;
+ bool pressure;
+ struct iio_channel *iio_chans;
+ struct iio_cb_buffer *iio_cb;
+ struct input_dev *input;
+ struct touchscreen_properties prop;
+ u8 ch_map[GRTS_CH_MAX];
+};
+
+static int grts_cb(const void *data, void *private)
+{
+ const u16 *touch_info = data;
+ struct grts_state *st = private;
+ unsigned int x, y, press = 0;
+
+ x = touch_info[st->ch_map[GRTS_CH_X]];
+ y = touch_info[st->ch_map[GRTS_CH_Y]];
+
+ if (st->ch_map[GRTS_CH_PRESSURE] < GRTS_MAX_CHANNELS) {
+ press = touch_info[st->ch_map[GRTS_CH_PRESSURE]];
+ } else if (st->ch_map[GRTS_CH_Z1] < GRTS_MAX_CHANNELS) {
+ unsigned int z1 = touch_info[st->ch_map[GRTS_CH_Z1]];
+ unsigned int z2 = touch_info[st->ch_map[GRTS_CH_Z2]];
+ unsigned int Rt;
+
+ if (likely(x && z1)) {
+ Rt = z2;
+ Rt -= z1;
+ Rt *= st->x_plate_ohms;
+ Rt = DIV_ROUND_CLOSEST(Rt, 16);
+ Rt *= x;
+ Rt /= z1;
+ Rt = DIV_ROUND_CLOSEST(Rt, 256);
+ /*
+ * On increased pressure the resistance (Rt) is
+ * decreasing so, convert values to make it looks as
+ * real pressure.
+ */
+ if (Rt < GRTS_DEFAULT_PRESSURE_MAX)
+ press = GRTS_DEFAULT_PRESSURE_MAX - Rt;
+ }
+ }
+
+ if ((!x && !y) || (st->pressure && (press < st->pressure_min))) {
+ /* 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_map_channel(struct grts_state *st, struct device *dev,
+ enum grts_ch_type type, const char *name,
+ bool optional)
+{
+ int idx;
+
+ idx = device_property_match_string(dev, "io-channel-names", name);
+ if (idx < 0) {
+ if (!optional)
+ return idx;
+ idx = GRTS_MAX_CHANNELS;
+ } else if (idx >= GRTS_MAX_CHANNELS) {
+ return -EOVERFLOW;
+ }
+
+ st->ch_map[type] = idx;
+ return 0;
+}
+
+static int grts_get_properties(struct grts_state *st, struct device *dev)
+{
+ int error;
+
+ error = grts_map_channel(st, dev, GRTS_CH_X, "x", false);
+ if (error)
+ return error;
+
+ error = grts_map_channel(st, dev, GRTS_CH_Y, "y", false);
+ if (error)
+ return error;
+
+ /* pressure is optional */
+ error = grts_map_channel(st, dev, GRTS_CH_PRESSURE, "pressure", true);
+ if (error)
+ return error;
+
+ if (st->ch_map[GRTS_CH_PRESSURE] < GRTS_MAX_CHANNELS) {
+ st->pressure = true;
+ return 0;
+ }
+
+ /* if no pressure is defined, try optional z1 + z2 */
+ error = grts_map_channel(st, dev, GRTS_CH_Z1, "z1", true);
+ if (error)
+ return error;
+
+ if (st->ch_map[GRTS_CH_Z1] >= GRTS_MAX_CHANNELS)
+ return 0;
+
+ /* if z1 is provided z2 is not optional */
+ error = grts_map_channel(st, dev, GRTS_CH_Z2, "z2", true);
+ if (error)
+ return error;
+
+ error = device_property_read_u32(dev,
+ "touchscreen-x-plate-ohms",
+ &st->x_plate_ohms);
+ if (error) {
+ dev_err(dev, "can't get touchscreen-x-plate-ohms property\n");
+ return error;
+ }
+
+ st->pressure = true;
+ return 0;
+}
+
+static int grts_probe(struct platform_device *pdev)
+{
+ struct grts_state *st;
+ struct input_dev *input;
+ struct device *dev = &pdev->dev;
+ int error;
+
+ st = devm_kzalloc(dev, sizeof(struct grts_state), GFP_KERNEL);
+ if (!st)
+ return -ENOMEM;
+
+ /* get the channels from IIO device */
+ st->iio_chans = devm_iio_channel_get_all(dev);
+ if (IS_ERR(st->iio_chans))
+ return dev_err_probe(dev, PTR_ERR(st->iio_chans), "can't get iio channels\n");
+
+ if (!device_property_present(dev, "io-channel-names"))
+ return -ENODEV;
+
+ error = grts_get_properties(st, dev);
+ if (error) {
+ dev_err(dev, "Failed to parse properties\n");
+ return error;
+ }
+
+ if (st->pressure) {
+ error = device_property_read_u32(dev,
+ "touchscreen-min-pressure",
+ &st->pressure_min);
+ if (error) {
+ dev_dbg(dev, "can't get touchscreen-min-pressure property.\n");
+ st->pressure_min = GRTS_DEFAULT_PRESSURE_MIN;
+ }
+ }
+
+ 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_min,
+ GRTS_DEFAULT_PRESSURE_MAX, 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");
+ return PTR_ERR(st->iio_cb);
+ }
+
+ error = devm_add_action_or_reset(dev, grts_disable, st->iio_cb);
+ if (error) {
+ dev_err(dev, "failed to add disable action.\n");
+ return error;
+ }
+
+ 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,
+ .of_match_table = 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");