Add the goldfish_rotary driver

Some Android Wear images have the rotary input,
this driver adds support to this input.

Bug: 117327079
Test: emulator -avd Wear_OS_Round_Chin_API_28 -kernel /tmp/qemu-kernel-x86_64-ranchu/kernel-qemu
Change-Id: I54826cc2eea3bbd847f5e3e5ccf217f82eaefacb
Signed-off-by: Roman Kiryanov <rkir@google.com>

arch/x86/configs/x86_64_ranchu_defconfig

@@ -267,6 +267,7 @@ CONFIG_INPUT_EVDEV=y
 CONFIG_INPUT_KEYRESET=y
 # CONFIG_KEYBOARD_ATKBD is not set
 CONFIG_KEYBOARD_GOLDFISH_EVENTS=y
+CONFIG_KEYBOARD_GOLDFISH_ROTARY=y
 # CONFIG_INPUT_MOUSE is not set
 CONFIG_INPUT_JOYSTICK=y
 CONFIG_JOYSTICK_XPAD=y

drivers/input/keyboard/Kconfig

@@ -551,6 +551,16 @@ config KEYBOARD_GOLDFISH_EVENTS
 	  To compile this driver as a module, choose M here: the
 	  module will be called goldfish-events.
 
+config KEYBOARD_GOLDFISH_ROTARY
+	depends on GOLDFISH
+	tristate "Rotary encoder device for Goldfish"
+	help
+	  Say Y here to get an input event device for the Goldfish virtual
+	  device emulator that acts as a rotary encoder.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called goldfish-rotary.
+
 config KEYBOARD_STOWAWAY
 	tristate "Stowaway keyboard"
 	select SERIO

drivers/input/keyboard/Makefile

@@ -21,6 +21,7 @@ obj-$(CONFIG_KEYBOARD_DAVINCI)		+= davinci_keyscan.o
 obj-$(CONFIG_KEYBOARD_DLINK_DIR685)	+= dlink-dir685-touchkeys.o
 obj-$(CONFIG_KEYBOARD_EP93XX)		+= ep93xx_keypad.o
 obj-$(CONFIG_KEYBOARD_GOLDFISH_EVENTS)	+= goldfish_events.o
+obj-$(CONFIG_KEYBOARD_GOLDFISH_ROTARY)	+= goldfish_rotary.o
 obj-$(CONFIG_KEYBOARD_GPIO)		+= gpio_keys.o
 obj-$(CONFIG_KEYBOARD_GPIO_POLLED)	+= gpio_keys_polled.o
 obj-$(CONFIG_KEYBOARD_TCA6416)		+= tca6416-keypad.o

drivers/input/keyboard/goldfish_rotary.c

+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/interrupt.h>
+#include <linux/types.h>
+#include <linux/limits.h>
+#include <linux/input.h>
+#include <linux/kernel.h>
+#include <linux/platform_device.h>
+#include <linux/irq.h>
+#include <linux/io.h>
+#include <linux/acpi.h>
+
+#ifndef CHAR_BIT
+#define CHAR_BIT 8
+#endif
+
+enum {
+	REG_READ        = 0x00,
+	REG_SET_PAGE    = 0x00,
+	REG_LEN         = 0x04,
+	REG_DATA        = 0x08,
+
+	PAGE_NAME       = 0x00000,
+	PAGE_EVBITS     = 0x10000,
+	PAGE_ABSDATA    = 0x20000 | EV_ABS,
+
+	IRQ_MAGIC       = 987642334
+};
+
+struct event_dev {
+	int magic;
+	int irq;
+	struct input_dev *input;
+	void __iomem *addr;
+	char name[0];
+};
+
+static irqreturn_t rotary_interrupt_impl(struct event_dev *edev)
+{
+	unsigned int type, code, value;
+
+	type = readl(edev->addr + REG_READ);
+	code = readl(edev->addr + REG_READ);
+	value = readl(edev->addr + REG_READ);
+
+	input_event(edev->input, type, code, value);
+	return IRQ_HANDLED;
+}
+
+static irqreturn_t rotary_interrupt(int irq, void *dev_id)
+{
+	struct event_dev *edev = dev_id;
+
+	if (edev->magic != IRQ_MAGIC)
+		return IRQ_NONE;
+
+	return rotary_interrupt_impl(edev);
+}
+
+static void rotary_import_bits(struct event_dev *edev,
+			       unsigned long bits[],
+			       unsigned int type, size_t count)
+{
+	void __iomem *addr = edev->addr;
+	int i, j;
+	size_t size;
+	uint8_t val;
+
+	writel(PAGE_EVBITS | type, addr + REG_SET_PAGE);
+
+	size = readl(addr + REG_LEN) * CHAR_BIT;
+	if (size < count)
+		count = size;
+
+	addr += REG_DATA;
+	for (i = 0; i < count; i += CHAR_BIT) {
+		val = readb(addr++);
+		for (j = 0; j < CHAR_BIT; j++)
+			if (val & 1 << j)
+				set_bit(i + j, bits);
+	}
+}
+
+static void rotary_import_abs_params(struct event_dev *edev)
+{
+	struct input_dev *input_dev = edev->input;
+	void __iomem *addr = edev->addr;
+	u32 val[4];
+	int count;
+	int i, j;
+
+	writel(PAGE_ABSDATA, addr + REG_SET_PAGE);
+
+	count = readl(addr + REG_LEN) / sizeof(val);
+	if (count > ABS_MAX)
+		count = ABS_MAX;
+
+	for (i = 0; i < count; i++) {
+		if (!test_bit(i, input_dev->absbit))
+			continue;
+
+		for (j = 0; j < ARRAY_SIZE(val); j++) {
+			int offset = (i * ARRAY_SIZE(val) + j) * sizeof(u32);
+			val[j] = readl(edev->addr + REG_DATA + offset);
+		}
+
+		input_set_abs_params(input_dev, i,
+				     val[0], val[1], val[2], val[3]);
+	}
+}
+
+static int rotary_probe(struct platform_device *pdev)
+{
+	struct input_dev *input_dev;
+	struct event_dev *edev;
+	struct resource *res;
+	unsigned int keymapnamelen;
+	void __iomem *addr;
+	int irq;
+	int i;
+	int error;
+
+	irq = platform_get_irq(pdev, 0);
+	if (irq < 0)
+		return -EINVAL;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (!res)
+		return -EINVAL;
+
+	addr = devm_ioremap(&pdev->dev, res->start, PAGE_SIZE);
+	if (!addr)
+		return -ENOMEM;
+
+	writel(PAGE_NAME, addr + REG_SET_PAGE);
+	keymapnamelen = readl(addr + REG_LEN);
+
+	edev = devm_kzalloc(&pdev->dev,
+			    sizeof(struct event_dev) + keymapnamelen + 1,
+			    GFP_KERNEL);
+	if (!edev)
+		return -ENOMEM;
+
+	input_dev = devm_input_allocate_device(&pdev->dev);
+	if (!input_dev)
+		return -ENOMEM;
+
+	edev->magic = IRQ_MAGIC;
+	edev->input = input_dev;
+	edev->addr = addr;
+	edev->irq = irq;
+
+	for (i = 0; i < keymapnamelen; i++)
+		edev->name[i] = readb(edev->addr + REG_DATA + i);
+
+	pr_debug("%s: keymap=%s\n", __func__, edev->name);
+
+	input_dev->name = edev->name;
+	input_dev->id.bustype = BUS_HOST;
+	rotary_import_bits(edev, input_dev->evbit, EV_SYN, EV_MAX);
+	rotary_import_bits(edev, input_dev->relbit, EV_REL, REL_MAX);
+	rotary_import_bits(edev, input_dev->absbit, EV_ABS, ABS_MAX);
+
+	rotary_import_abs_params(edev);
+
+	error = devm_request_irq(&pdev->dev, edev->irq, rotary_interrupt,
+				 IRQF_SHARED, "goldfish-rotary", edev);
+	if (error)
+		return error;
+
+	error = input_register_device(input_dev);
+	if (error)
+		return error;
+
+	return 0;
+}
+
+static const struct of_device_id goldfish_rotary_of_match[] = {
+	{ .compatible = "generic,goldfish-rotary", },
+	{},
+};
+MODULE_DEVICE_TABLE(of, goldfish_rotary_of_match);
+
+static const struct acpi_device_id goldfish_rotary_acpi_match[] = {
+	{ "GFSH0008", 0 },
+	{ },
+};
+MODULE_DEVICE_TABLE(acpi, goldfish_rotary_acpi_match);
+
+static struct platform_driver rotary_driver = {
+	.probe	= rotary_probe,
+	.driver	= {
+		.owner	= THIS_MODULE,
+		.name	= "goldfish_rotary",
+		.of_match_table = goldfish_rotary_of_match,
+		.acpi_match_table = ACPI_PTR(goldfish_rotary_acpi_match),
+	},
+};
+
+module_platform_driver(rotary_driver);
+
+MODULE_AUTHOR("Nimrod Gileadi");
+MODULE_DESCRIPTION("Goldfish Rotary Encoder Device");
+MODULE_LICENSE("GPL v2");