[PATCH] drivers: input: misc: Add driver touchscreen-buttons to support physically labeled buttons on touchscreen surfaces

[PATCH] drivers: input: misc: Add driver touchscreen-buttons to support physically labeled buttons on touchscreen surfaces

[Dev Null]

Adds a driver for supporting permanet, physically labeled, buttons on touchscreen surfaces. As are common on android phones designed with android 1.0 to 2.3 in mind. The driver works by attaching to another input device and mirroring its events, while inserting key events and filtering for touches that land on the buttons. Buttons are arbitrary rectangles configurable via dts.

diff --git a/drivers/input/misc/Kconfig b/drivers/input/misc/Kconfig
index 7e2e658d551c..508c0424c423 100644
--- a/drivers/input/misc/Kconfig
+++ b/drivers/input/misc/Kconfig
@@ -339,6 +339,14 @@ config INPUT_CPCAP_PWRBUTTON
 	  To compile this driver as a module, choose M here. The module will
 	  be called cpcap-pwrbutton.
 
+config INPUT_TOUCHSCREEN_BUTTONS
+	tristate "Touchscreen Buttons"
+	help
+	  Say Y here if you want to enable buttons on touchscreen devices.
+
+	  To compile this driver as a module, choose M here. The module will
+	  be called touchscreen-buttons.
+
 config INPUT_WISTRON_BTNS
 	tristate "x86 Wistron laptop button interface"
 	depends on X86_32
diff --git a/drivers/input/misc/Makefile b/drivers/input/misc/Makefile
index 8fd187f314bd..3b34378cb79f 100644
--- a/drivers/input/misc/Makefile
+++ b/drivers/input/misc/Makefile
@@ -85,4 +85,5 @@ obj-$(CONFIG_INPUT_WM831X_ON)		+= wm831x-on.o
 obj-$(CONFIG_INPUT_XEN_KBDDEV_FRONTEND)	+= xen-kbdfront.o
 obj-$(CONFIG_INPUT_YEALINK)		+= yealink.o
 obj-$(CONFIG_INPUT_IDEAPAD_SLIDEBAR)	+= ideapad_slidebar.o
+obj-$(CONFIG_INPUT_TOUCHSCREEN_BUTTONS)	+= touchscreen-buttons.o
 
diff --git a/drivers/input/misc/touchscreen-buttons.c b/drivers/input/misc/touchscreen-buttons.c
new file mode 100644
index 000000000000..b78a98dc21b5
--- /dev/null
+++ b/drivers/input/misc/touchscreen-buttons.c
@@ -0,0 +1,505 @@
+/**
+ * Touchscreen Virutal Button Input Driver
+ *
+ * Copyright (C) 2020 Carl Klemm <carl@uvos.xyz>
+ *
+ * This file is subject to the terms and conditions of the GNU General
+ * Public License. See the file "COPYING" in the main directory of this
+ * archive for more details.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#include <linux/module.h>
+#include <linux/types.h>
+#include <linux/platform_device.h>
+#include <linux/errno.h>
+#include <linux/input.h>
+#include <linux/slab.h>
+#include <linux/of.h>
+#include <linux/of_platform.h>
+#include <linux/kernel.h>
+#include <linux/limits.h>
+#include <linux/input/mt.h>
+#include <linux/device/bus.h>
+#include <linux/string.h>
+#include <linux/sysfs.h>
+
+#define EVENT_QUEUE_SIZE 32
+
+struct touchscreen_button {
+	__u32 x;
+	__u32 y;
+	__u32 width;
+	__u32 height;
+	__u32 keycode;
+	__u8 depressed;
+};
+
+struct touchscreen_button_map {
+	struct touchscreen_button *buttons;
+	__u32 count;
+	struct device_node *ts_node;
+};
+
+struct event {
+	unsigned int type;
+	unsigned int code;
+	int value;
+};
+
+struct event_queue {
+	struct event events[EVENT_QUEUE_SIZE];
+	unsigned int lastindex;
+};
+
+struct touchscreen_buttons {
+	struct device *dev;
+	struct input_dev *idev;
+	struct touchscreen_button_map *map;
+	struct input_handler *handler;
+	struct input_handle *ts_handle;
+	struct event_queue queue;
+};
+
+static const struct input_device_id touchscreen_buttons_ids[] = {
+	{
+	 .flags = INPUT_DEVICE_ID_MATCH_EVBIT,
+	 .evbit = {BIT_MASK(EV_ABS)},
+	 },
+	{
+	 .flags = INPUT_DEVICE_ID_MATCH_EVBIT,
+	 .evbit = {BIT_MASK(EV_KEY)},
+	 },
+	{
+	 .flags = INPUT_DEVICE_ID_MATCH_EVBIT,
+	 .evbit = {BIT_MASK(EV_SYN)},
+	 },
+	{},
+};
+
+static ssize_t touchscreen_buttons_show_users(struct device *dev, struct device_attribute *attr, char *buf)
+{
+	int len = 0;
+	static char buffer[32];
+	struct touchscreen_buttons *buttons;
+
+	buf = buffer;
+
+	buttons = dev_get_drvdata(dev);
+
+	if (!buttons) {
+		dev_err(dev, "Sysfs file read but device is not ready, %p\n", buttons);
+		return 0;
+	}
+
+	len = snprintf(buffer, 32, "%u\n", buttons->idev->users);
+	if (len > 32)
+		len = 32;
+	else if (len < 0)
+		return 0;
+
+	return len;
+}
+
+static const struct device_attribute users_attribute = __ATTR(users, 0444, touchscreen_buttons_show_users, 0);
+
+static int touchscreen_buttons_process_syn(const struct event_queue *queue, const struct touchscreen_button_map
+					   *map, struct input_dev *idev)
+{
+	u32 i;
+	int x, y, ret, pressed;
+
+	x = INT_MIN;
+	y = INT_MIN;
+	pressed = -1;
+	ret = 0;
+
+	for (i = 0; i < queue->lastindex; ++i) {
+		const struct event *ev;
+
+		ev = &queue->events[i];
+		if (ev->type == EV_ABS && ev->code == ABS_X)
+			x = ev->value;
+		else if (ev->type == EV_ABS && ev->code == ABS_Y)
+			y = ev->value;
+		else if (ev->type == EV_KEY && ev->code == BTN_TOUCH)
+			pressed = ev->value;
+	}
+
+	for (i = 0; i < map->count; ++i) {
+		struct touchscreen_button *button = &map->buttons[i];
+
+		if (pressed == 1 &&
+		    button->x <= x &&
+		    button->y <= y &&
+		    button->width + button->x >= x && button->height + button->y >= y
+		    && button->depressed == 0) {
+			input_report_key(idev, button->keycode, 1);
+			button->depressed = 1;
+			ret = 1;
+		} else if (button->depressed == 1) {
+			if (pressed == 0) {
+				input_report_key(idev, button->keycode, 0);
+				button->depressed = 0;
+			}
+			ret = 2;
+		}
+	}
+
+	if (ret != 0)
+		input_event(idev, EV_SYN, SYN_REPORT, 0);
+
+	return ret;
+}
+
+static void touchscreen_buttons_resend_events(const struct event_queue *queue, struct input_dev *idev)
+{
+	__u32 i;
+	for (i = 0; i < queue->lastindex; ++i) {
+		input_event(idev, queue->events[i].type, queue->events[i].code, queue->events[i].value);
+	}
+	input_event(idev, EV_SYN, SYN_REPORT, 0);
+}
+
+static void touchscreen_buttons_copy_mt_slots(struct input_dev *target, struct input_dev *source)
+{
+	if (source->mt && target->mt && source->mt->num_slots == target->mt->num_slots) {
+		memcpy(target->mt->slots, source->mt->slots,
+		       sizeof(struct input_mt_slot) * source->mt->num_slots);
+	}
+}
+
+static void touchscreen_buttons_input_event(struct input_handle *handle,
+					    unsigned int type, unsigned int code, int value)
+{
+
+	struct touchscreen_buttons *buttons;
+
+	buttons = handle->private;
+
+	if (type == EV_SYN && code == SYN_REPORT) {
+		if (touchscreen_buttons_process_syn(&buttons->queue, buttons->map, buttons->idev) == 0) {
+			touchscreen_buttons_resend_events(&buttons->queue, buttons->idev);
+		}
+		buttons->queue.lastindex = 0;
+	} else if (buttons->queue.lastindex < EVENT_QUEUE_SIZE && buttons->queue.lastindex >= 0) {
+		buttons->queue.events[buttons->queue.lastindex].type = type;
+		buttons->queue.events[buttons->queue.lastindex].code = code;
+		buttons->queue.events[buttons->queue.lastindex].value = value;
+		++buttons->queue.lastindex;
+	} else {
+		dev_warn(buttons->dev,
+			 "event_qeue overrun, will not caputure events until next SYN_REPORT\n");
+	}
+}
+
+static void touchscreen_buttons_merge_capabilitys(struct input_dev *target, struct input_dev *source)
+{
+	unsigned int i;
+	for (i = 0; i < BITS_TO_LONGS(INPUT_PROP_CNT); ++i)
+		target->propbit[i] = target->propbit[i] | source->propbit[i];
+	for (i = 0; i < BITS_TO_LONGS(EV_CNT); ++i)
+		target->evbit[i] = target->evbit[i] | source->evbit[i];
+	for (i = 0; i < BITS_TO_LONGS(KEY_CNT); ++i)
+		target->keybit[i] = target->keybit[i] | source->keybit[i];
+	for (i = 0; i < BITS_TO_LONGS(REL_CNT); ++i)
+		target->relbit[i] = target->relbit[i] | source->relbit[i];
+	for (i = 0; i < BITS_TO_LONGS(ABS_CNT); ++i)
+		target->absbit[i] = target->absbit[i] | source->absbit[i];
+	for (i = 0; i < BITS_TO_LONGS(MSC_CNT); ++i)
+		target->mscbit[i] = target->mscbit[i] | source->mscbit[i];
+	for (i = 0; i < BITS_TO_LONGS(LED_CNT); ++i)
+		target->ledbit[i] = target->ledbit[i] | source->ledbit[i];
+	for (i = 0; i < BITS_TO_LONGS(SND_CNT); ++i)
+		target->sndbit[i] = target->sndbit[i] | source->sndbit[i];
+	for (i = 0; i < BITS_TO_LONGS(FF_CNT); ++i)
+		target->ffbit[i] = target->ffbit[i] | source->ffbit[i];
+	for (i = 0; i < BITS_TO_LONGS(SW_CNT); ++i)
+		target->swbit[i] = target->swbit[i] | source->swbit[i];
+
+	if (*source->evbit & (1 << EV_ABS)) {
+		input_alloc_absinfo(target);
+		for (i = 0; i < ABS_CNT; ++i)
+			target->absinfo[i] = source->absinfo[i];
+		if (source->mt) {
+			input_mt_init_slots(target, source->mt->num_slots, source->mt->flags);
+			touchscreen_buttons_copy_mt_slots(target, source);
+		}
+	}
+
+}
+
+static int touchscreen_buttons_input_connect(struct input_handler *handler,
+					     struct input_dev *dev, const struct input_device_id *id)
+{
+	struct touchscreen_buttons *buttons;
+
+	buttons = handler->private;
+
+	if ((!buttons->ts_handle && device_match_of_node(&dev->dev, buttons->map->ts_node))
+	    || (dev->dev.parent && device_match_of_node(dev->dev.parent, buttons->map->ts_node))) {
+		int error;
+
+		dev_info(buttons->dev, "Binding to device: %s\n", dev_name(&dev->dev));
+
+		buttons->ts_handle = kzalloc(sizeof(*buttons->ts_handle), GFP_KERNEL);
+		if (!buttons->ts_handle)
+			return -ENOMEM;
+
+		buttons->ts_handle->dev = dev;
+		buttons->ts_handle->handler = handler;
+		buttons->ts_handle->name = "touchscreen-buttons";
+		buttons->ts_handle->private = handler->private;
+		buttons->queue.lastindex = 0;
+
+		touchscreen_buttons_merge_capabilitys(buttons->idev, dev);
+
+		error = input_register_handle(buttons->ts_handle);
+		if (error) {
+			dev_err(buttons->dev, "Failed to register input handler, error %d\n", error);
+			kfree(buttons->ts_handle);
+			buttons->ts_handle = NULL;
+			return error;
+		}
+		if (buttons->idev->users > 0 && buttons->ts_handle->open == 0) {
+			error = input_open_device(buttons->ts_handle);
+			if (error) {
+				dev_err(buttons->dev, "Failed to open input device, error %d\n", error);
+				input_unregister_handle(buttons->ts_handle);
+				kfree(buttons->ts_handle);
+				buttons->ts_handle = NULL;
+				return error;
+			}
+		}
+	}
+
+	return 0;
+}
+
+static void touchscreen_buttons_input_disconnect(struct input_handle *handle)
+{
+	struct touchscreen_buttons *buttons;
+
+	buttons = handle->private;
+
+	if (handle == buttons->ts_handle) {
+		input_close_device(handle);
+		input_unregister_handle(handle);
+		kfree(handle);
+		buttons->ts_handle = NULL;
+		dev_info(buttons->dev, "Touchscreen device disconnected buttons disabled\n");
+	} else {
+		dev_err(buttons->dev, "Unkown device disconnected, %p should be %p", handle,
+			buttons->ts_handle);
+	}
+}
+
+static struct touchscreen_button_map
+*touchscreen_buttons_get_devtree_pdata(struct device *dev)
+{
+	struct touchscreen_button_map *map;
+	struct fwnode_handle *child_node;
+	struct device_node *node;
+	int i;
+
+	map = kzalloc(sizeof(*map), GFP_KERNEL);
+	if (!map)
+		return ERR_PTR(-ENOMEM);
+
+	map->count = device_get_child_node_count(dev);
+	if (map->count == 0)
+		return ERR_PTR(-ENODEV);
+
+	map->buttons = kzalloc(sizeof(*map->buttons) * map->count, GFP_KERNEL);
+	if (!map->buttons)
+		return ERR_PTR(-ENOMEM);
+
+	node = dev->of_node;
+	map->ts_node = of_parse_phandle(node, "touchscreen_phandle", 0);
+	if (!map->ts_node) {
+		dev_err(dev, "touchscreen_phandle node missing\n");
+		return ERR_PTR(-ENODEV);
+	}
+
+	dev_info(dev, "Device_node name: %s\n", map->ts_node->name);
+
+	i = 0;
+	device_for_each_child_node(dev, child_node) {
+		struct touchscreen_button *button;
+		button = &map->buttons[i];
+		fwnode_property_read_u32(child_node, "x-position", &button->x);
+		fwnode_property_read_u32(child_node, "y-position", &button->y);
+		fwnode_property_read_u32(child_node, "x-size", &button->width);
+		fwnode_property_read_u32(child_node, "y-size", &button->height);
+		fwnode_property_read_u32(child_node, "keycode", &button->keycode);
+		dev_info(dev,
+			 "Adding button at x=%u y=%u size %u x %u keycode=%u\n",
+			 button->x, button->y, button->width, button->height, button->keycode);
+		++i;
+	}
+	return map;
+}
+
+int touchscreen_buttons_idev_opened(struct input_dev *idev)
+{
+	struct touchscreen_buttons *buttons;
+	buttons = dev_get_drvdata(idev->dev.parent);
+	if (buttons && buttons->ts_handle) {
+		if (buttons->ts_handle->open == 0) {
+			int error;
+
+			error = input_open_device(buttons->ts_handle);
+			if (error) {
+				dev_err(idev->dev.parent, "Failed to open input device, error %d\n", error);
+				input_unregister_handle(buttons->ts_handle);
+				kfree(buttons->ts_handle);
+				buttons->ts_handle = NULL;
+				return error;
+			}
+			dev_dbg(idev->dev.parent, "idev opened\n");
+		} else {
+			dev_info(idev->dev.parent, "idev allready opened\n");
+		}
+	} else {
+		dev_warn(idev->dev.parent,
+			 "Input device opend but touchscreen not opened. %p %p\n", buttons,
+			 buttons->ts_handle);
+	}
+	return 0;
+}
+
+void touchscreen_buttons_idev_closed(struct input_dev *idev)
+{
+	struct touchscreen_buttons *buttons;
+	buttons = dev_get_drvdata(idev->dev.parent);
+	if (buttons && buttons->ts_handle && buttons->ts_handle->open != 0) {
+		input_close_device(buttons->ts_handle);
+		dev_dbg(idev->dev.parent, "idev closed\n");
+	} else {
+		dev_warn(idev->dev.parent, "Close called on non exsistant buttons.\n");
+	}
+}
+
+static int touchscreen_buttons_probe(struct platform_device *pdev)
+{
+	struct touchscreen_buttons *buttons;
+	int error, i;
+
+	buttons = kzalloc(sizeof(*buttons), GFP_KERNEL);
+	if (!buttons)
+		return -ENOMEM;
+
+	dev_set_drvdata(&pdev->dev, buttons);
+
+	buttons->queue.lastindex = 0;
+
+	buttons->map = touchscreen_buttons_get_devtree_pdata(&pdev->dev);
+	if (IS_ERR(buttons->map))
+		return PTR_ERR(buttons->map);
+
+	/*input device */
+	buttons->idev = input_allocate_device();
+	if (!buttons->idev)
+		return -ENOMEM;
+
+	buttons->dev = &pdev->dev;
+
+	buttons->idev->name = "touchscreen-buttons";
+	buttons->idev->phys = "touchscreen-buttons/input0";
+	buttons->idev->dev.parent = buttons->dev;
+	buttons->idev->open = touchscreen_buttons_idev_opened;
+	buttons->idev->close = touchscreen_buttons_idev_closed;
+	for (i = 0; i < buttons->map->count; ++i) {
+		input_set_capability(buttons->idev, EV_KEY, buttons->map->buttons[i].keycode);
+	}
+
+	/*handler for touchscreen input device */
+	buttons->handler = kzalloc(sizeof(*buttons->handler), GFP_KERNEL);
+
+	buttons->handler->event = touchscreen_buttons_input_event;
+	buttons->handler->connect = touchscreen_buttons_input_connect;
+	buttons->handler->disconnect = touchscreen_buttons_input_disconnect;
+	buttons->handler->name = "touchscreen-buttons";
+	buttons->handler->id_table = touchscreen_buttons_ids;
+	buttons->handler->private = buttons;
+
+	error = input_register_handler(buttons->handler);
+	if (error) {
+		dev_err(&pdev->dev, "Input handler register failed: %d\n", error);
+		return error;
+	}
+
+	error = input_register_device(buttons->idev);
+	if (error) {
+		dev_err(&pdev->dev, "Input device register failed: %d\n", error);
+		return error;
+	}
+
+	error = device_create_file(&pdev->dev, &users_attribute);
+	if (error) {
+		dev_err(&pdev->dev, "Registering sysfs file failed: %d\n", error);
+	}
+
+	return 0;
+}
+
+static int touchscreen_buttons_remove(struct platform_device *pdev)
+{
+	struct touchscreen_buttons *buttons;
+
+	buttons = dev_get_drvdata(&pdev->dev);
+
+	device_remove_file(&pdev->dev, &users_attribute);
+
+	input_unregister_handler(buttons->handler);
+	if (buttons->ts_handle) {
+		if (buttons->ts_handle->open != 0) {
+			input_close_device(buttons->ts_handle);
+		}
+		input_unregister_handle(buttons->ts_handle);
+	}
+
+	input_unregister_device(buttons->idev);
+
+	if (buttons->ts_handle)
+		kfree(buttons->ts_handle);
+
+	if (buttons->map) {
+		if (buttons->map->buttons)
+			kfree(buttons->map->buttons);
+		kfree(buttons->map);
+	}
+	kfree(buttons->handler);
+	kfree(buttons);
+
+	return 0;
+}
+
+#ifdef CONFIG_OF
+static const struct of_device_id touchscreen_buttons_dt_match_table[] = {
+	{.compatible = "touchscreen-buttons"},
+	{},
+};
+
+MODULE_DEVICE_TABLE(of, touchscreen_buttons_dt_match_table);
+#endif
+
+static struct platform_driver touchscreen_buttons_driver = {
+	.probe = touchscreen_buttons_probe,
+	.remove = touchscreen_buttons_remove,
+	.driver = {
+		   .name = "touchscreen-buttons",
+		   .of_match_table = of_match_ptr(touchscreen_buttons_dt_match_table),
+		   },
+};
+
+module_platform_driver(touchscreen_buttons_driver);
+
+MODULE_ALIAS("platform:touchscreen-buttons");
+MODULE_DESCRIPTION("touchscreen-buttons");
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Carl Klemm <carl@uvos.xyz>");

-- 
Dev Null <devnull@uvos.xyz>