platform/x86: Support for EC-connected GPIOs for identify LED/button on Barco P50 board

Add a driver providing access to the GPIOs for the identify button and led
present on Barco P50 board, based on the pcengines-apuv2.c driver.

There is unfortunately no suitable ACPI entry for the EC communication
interface, so instead bind to boards with "P50" as their DMI product family
and hard code the I/O port number (0x299).

The driver also hooks up the leds-gpio and gpio-keys-polled drivers to the
GPIOs, so they are finally exposed as:

LED:
/sys/class/leds/identify

Button: (/proc/bus/input/devices)
I: Bus=0019 Vendor=0001 Product=0001 Version=0100
N: Name="identify"
P: Phys=gpio-keys-polled/input0
S: Sysfs=/devices/platform/barco-p50-gpio/gpio-keys-polled/input/input10
U: Uniq=
H: Handlers=event10
B: PROP=0
B: EV=3
B: KEY=1000000 0 0 0 0 0 0

Signed-off-by: Santosh Kumar Yadav <santoshkumar.yadav@barco.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>
Link: https://lore.kernel.org/r/20211020123634.2638-1-peter@korsgaard.com
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>

MAINTAINERS

@@ -3215,6 +3215,12 @@ F:	drivers/video/backlight/
 F:	include/linux/backlight.h
 F:	include/linux/pwm_backlight.h
 
+BARCO P50 GPIO DRIVER
+M:	Santosh Kumar Yadav <santoshkumar.yadav@barco.com>
+M:	Peter Korsgaard <peter.korsgaard@barco.com>
+S:	Maintained
+F:	drivers/platform/x86/barco-p50-gpio.c
+
 BATMAN ADVANCED
 M:	Marek Lindner <mareklindner@neomailbox.ch>
 M:	Simon Wunderlich <sw@simonwunderlich.de>

drivers/platform/x86/Kconfig

@@ -729,6 +729,16 @@ config PCENGINES_APU2
 	  To compile this driver as a module, choose M here: the module
 	  will be called pcengines-apuv2.
 
+config BARCO_P50_GPIO
+	tristate "Barco P50 GPIO driver for identify LED/button"
+	depends on GPIOLIB
+	help
+	  This driver provides access to the GPIOs for the identify button
+	  and led present on Barco P50 board.
+
+	  To compile this driver as a module, choose M here: the module
+	  will be called barco-p50-gpio.
+
 config SAMSUNG_LAPTOP
 	tristate "Samsung Laptop driver"
 	depends on RFKILL || RFKILL = n

drivers/platform/x86/Makefile

@@ -81,6 +81,9 @@ obj-$(CONFIG_XO1_RFKILL)	+= xo1-rfkill.o
 # PC Engines
 obj-$(CONFIG_PCENGINES_APU2)	+= pcengines-apuv2.o
 
+# Barco
+obj-$(CONFIG_BARCO_P50_GPIO)	+= barco-p50-gpio.o
+
 # Samsung
 obj-$(CONFIG_SAMSUNG_LAPTOP)	+= samsung-laptop.o
 obj-$(CONFIG_SAMSUNG_Q10)	+= samsung-q10.o

drivers/platform/x86/barco-p50-gpio.c

@@ -0,0 +1,436 @@
+// SPDX-License-Identifier: GPL-2.0+
+
+/*
+ * Support for EC-connected GPIOs for identify
+ * LED/button on Barco P50 board
+ *
+ * Copyright (C) 2021 Barco NV
+ * Author: Santosh Kumar Yadav <santoshkumar.yadav@barco.com>
+ */
+
+#define pr_fmt(fmt)	KBUILD_MODNAME ": " fmt
+
+#include <linux/io.h>
+#include <linux/delay.h>
+#include <linux/dmi.h>
+#include <linux/err.h>
+#include <linux/io.h>
+#include <linux/kernel.h>
+#include <linux/leds.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/gpio_keys.h>
+#include <linux/gpio/driver.h>
+#include <linux/gpio/machine.h>
+#include <linux/input.h>
+
+
+#define DRIVER_NAME		"barco-p50-gpio"
+
+/* GPIO lines */
+#define P50_GPIO_LINE_LED	0
+#define P50_GPIO_LINE_BTN	1
+
+/* GPIO IO Ports */
+#define P50_GPIO_IO_PORT_BASE	0x299
+
+#define P50_PORT_DATA		0x00
+#define P50_PORT_CMD		0x01
+
+#define P50_STATUS_OBF		0x01 /* EC output buffer full */
+#define P50_STATUS_IBF		0x02 /* EC input buffer full */
+
+#define P50_CMD_READ		0xa0
+#define P50_CMD_WRITE		0x50
+
+/* EC mailbox registers */
+#define P50_MBOX_REG_CMD	0x00
+#define P50_MBOX_REG_STATUS	0x01
+#define P50_MBOX_REG_PARAM	0x02
+#define P50_MBOX_REG_DATA	0x03
+
+#define P50_MBOX_CMD_READ_GPIO	0x11
+#define P50_MBOX_CMD_WRITE_GPIO	0x12
+#define P50_MBOX_CMD_CLEAR	0xff
+
+#define P50_MBOX_STATUS_SUCCESS	0x01
+
+#define P50_MBOX_PARAM_LED	0x12
+#define P50_MBOX_PARAM_BTN	0x13
+
+
+struct p50_gpio {
+	struct gpio_chip gc;
+	struct mutex lock;
+	unsigned long base;
+	struct platform_device *leds_pdev;
+	struct platform_device *keys_pdev;
+};
+
+static struct platform_device *gpio_pdev;
+
+static int gpio_params[] = {
+	[P50_GPIO_LINE_LED] = P50_MBOX_PARAM_LED,
+	[P50_GPIO_LINE_BTN] = P50_MBOX_PARAM_BTN,
+};
+
+static const char * const gpio_names[] = {
+	[P50_GPIO_LINE_LED] = "identify-led",
+	[P50_GPIO_LINE_BTN] = "identify-button",
+};
+
+
+static struct gpiod_lookup_table p50_gpio_led_table = {
+	.dev_id = "leds-gpio",
+	.table = {
+		GPIO_LOOKUP_IDX(DRIVER_NAME, P50_GPIO_LINE_LED, NULL, 0, GPIO_ACTIVE_HIGH),
+		{}
+	}
+};
+
+/* GPIO LEDs */
+static struct gpio_led leds[] = {
+	{ .name = "identify" }
+};
+
+static struct gpio_led_platform_data leds_pdata = {
+	.num_leds = ARRAY_SIZE(leds),
+	.leds = leds,
+};
+
+/* GPIO keyboard */
+static struct gpio_keys_button buttons[] = {
+	{
+		.code = KEY_RESTART,
+		.gpio = P50_GPIO_LINE_BTN,
+		.active_low = 1,
+		.type = EV_KEY,
+		.value = 1,
+	},
+};
+
+static struct gpio_keys_platform_data keys_pdata = {
+	.buttons = buttons,
+	.nbuttons = ARRAY_SIZE(buttons),
+	.poll_interval = 100,
+	.rep = 0,
+	.name = "identify",
+};
+
+
+/* low level access routines */
+
+static int p50_wait_ec(struct p50_gpio *p50, int mask, int expected)
+{
+	int i, val;
+
+	for (i = 0; i < 100; i++) {
+		val = inb(p50->base + P50_PORT_CMD) & mask;
+		if (val == expected)
+			return 0;
+		usleep_range(500, 2000);
+	}
+
+	dev_err(p50->gc.parent, "Timed out waiting for EC (0x%x)\n", val);
+	return -ETIMEDOUT;
+}
+
+
+static int p50_read_mbox_reg(struct p50_gpio *p50, int reg)
+{
+	int ret;
+
+	ret = p50_wait_ec(p50, P50_STATUS_IBF, 0);
+	if (ret)
+		return ret;
+
+	/* clear output buffer flag, prevent unfinished commands */
+	inb(p50->base + P50_PORT_DATA);
+
+	/* cmd/address */
+	outb(P50_CMD_READ | reg, p50->base + P50_PORT_CMD);
+
+	ret = p50_wait_ec(p50, P50_STATUS_OBF, P50_STATUS_OBF);
+	if (ret)
+		return ret;
+
+	return inb(p50->base + P50_PORT_DATA);
+}
+
+static int p50_write_mbox_reg(struct p50_gpio *p50, int reg, int val)
+{
+	int ret;
+
+	ret = p50_wait_ec(p50, P50_STATUS_IBF, 0);
+	if (ret)
+		return ret;
+
+	/* cmd/address */
+	outb(P50_CMD_WRITE | reg, p50->base + P50_PORT_CMD);
+
+	ret = p50_wait_ec(p50, P50_STATUS_IBF, 0);
+	if (ret)
+		return ret;
+
+	/* data */
+	outb(val, p50->base + P50_PORT_DATA);
+
+	return 0;
+}
+
+
+/* mbox routines */
+
+static int p50_wait_mbox_idle(struct p50_gpio *p50)
+{
+	int i, val;
+
+	for (i = 0; i < 1000; i++) {
+		val = p50_read_mbox_reg(p50, P50_MBOX_REG_CMD);
+		/* cmd is 0 when idle */
+		if (val <= 0)
+			return val;
+
+		usleep_range(500, 2000);
+	}
+
+	dev_err(p50->gc.parent,	"Timed out waiting for EC mbox idle (CMD: 0x%x)\n", val);
+
+	return -ETIMEDOUT;
+}
+
+static int p50_send_mbox_cmd(struct p50_gpio *p50, int cmd, int param, int data)
+{
+	int ret;
+
+	ret = p50_wait_mbox_idle(p50);
+	if (ret)
+		return ret;
+
+	ret = p50_write_mbox_reg(p50, P50_MBOX_REG_DATA, data);
+	if (ret)
+		return ret;
+
+	ret = p50_write_mbox_reg(p50, P50_MBOX_REG_PARAM, param);
+	if (ret)
+		return ret;
+
+	ret = p50_write_mbox_reg(p50, P50_MBOX_REG_CMD, cmd);
+	if (ret)
+		return ret;
+
+	ret = p50_wait_mbox_idle(p50);
+	if (ret)
+		return ret;
+
+	ret = p50_read_mbox_reg(p50, P50_MBOX_REG_STATUS);
+	if (ret < 0)
+		return ret;
+
+	if (ret == P50_MBOX_STATUS_SUCCESS)
+		return 0;
+
+	dev_err(p50->gc.parent,	"Mbox command failed (CMD=0x%x STAT=0x%x PARAM=0x%x DATA=0x%x)\n",
+		cmd, ret, param, data);
+
+	return -EIO;
+}
+
+
+/* gpio routines */
+
+static int p50_gpio_get_direction(struct gpio_chip *gc, unsigned int offset)
+{
+	switch (offset) {
+	case P50_GPIO_LINE_BTN:
+		return GPIO_LINE_DIRECTION_IN;
+
+	case P50_GPIO_LINE_LED:
+		return GPIO_LINE_DIRECTION_OUT;
+
+	default:
+		return -EINVAL;
+	}
+}
+
+static int p50_gpio_get(struct gpio_chip *gc, unsigned int offset)
+{
+	struct p50_gpio *p50 = gpiochip_get_data(gc);
+	int ret;
+
+	mutex_lock(&p50->lock);
+
+	ret = p50_send_mbox_cmd(p50, P50_MBOX_CMD_READ_GPIO, gpio_params[offset], 0);
+	if (ret == 0)
+		ret = p50_read_mbox_reg(p50, P50_MBOX_REG_DATA);
+
+	mutex_unlock(&p50->lock);
+
+	return ret;
+}
+
+static void p50_gpio_set(struct gpio_chip *gc, unsigned int offset, int value)
+{
+	struct p50_gpio *p50 = gpiochip_get_data(gc);
+
+	mutex_lock(&p50->lock);
+
+	p50_send_mbox_cmd(p50, P50_MBOX_CMD_WRITE_GPIO, gpio_params[offset], value);
+
+	mutex_unlock(&p50->lock);
+}
+
+static int p50_gpio_probe(struct platform_device *pdev)
+{
+	struct p50_gpio *p50;
+	struct resource *res;
+	int ret;
+
+	res = platform_get_resource(pdev, IORESOURCE_IO, 0);
+	if (!res) {
+		dev_err(&pdev->dev, "Cannot get I/O ports\n");
+		return -ENODEV;
+	}
+
+	if (!devm_request_region(&pdev->dev, res->start, resource_size(res), pdev->name)) {
+		dev_err(&pdev->dev, "Unable to reserve I/O region\n");
+		return -EBUSY;
+	}
+
+	p50 = devm_kzalloc(&pdev->dev, sizeof(*p50), GFP_KERNEL);
+	if (!p50)
+		return -ENOMEM;
+
+	platform_set_drvdata(pdev, p50);
+	mutex_init(&p50->lock);
+	p50->base = res->start;
+	p50->gc.owner = THIS_MODULE;
+	p50->gc.parent = &pdev->dev;
+	p50->gc.label = dev_name(&pdev->dev);
+	p50->gc.ngpio = ARRAY_SIZE(gpio_names);
+	p50->gc.names = gpio_names;
+	p50->gc.can_sleep = true;
+	p50->gc.base = -1;
+	p50->gc.get_direction = p50_gpio_get_direction;
+	p50->gc.get = p50_gpio_get;
+	p50->gc.set = p50_gpio_set;
+
+
+	/* reset mbox */
+	ret = p50_wait_mbox_idle(p50);
+	if (ret)
+		return ret;
+
+	ret = p50_write_mbox_reg(p50, P50_MBOX_REG_CMD, P50_MBOX_CMD_CLEAR);
+	if (ret)
+		return ret;
+
+	ret = p50_wait_mbox_idle(p50);
+	if (ret)
+		return ret;
+
+
+	ret = devm_gpiochip_add_data(&pdev->dev, &p50->gc, p50);
+	if (ret < 0) {
+		dev_err(&pdev->dev, "Could not register gpiochip: %d\n", ret);
+		return ret;
+	}
+
+	gpiod_add_lookup_table(&p50_gpio_led_table);
+
+	p50->leds_pdev = platform_device_register_data(&pdev->dev,
+		"leds-gpio", PLATFORM_DEVID_NONE, &leds_pdata, sizeof(leds_pdata));
+
+	if (IS_ERR(p50->leds_pdev)) {
+		ret = PTR_ERR(p50->leds_pdev);
+		dev_err(&pdev->dev, "Could not register leds-gpio: %d\n", ret);
+		goto err_leds;
+	}
+
+	/* gpio-keys-polled uses old-style gpio interface, pass the right identifier */
+	buttons[0].gpio += p50->gc.base;
+
+	p50->keys_pdev =
+		platform_device_register_data(&pdev->dev, "gpio-keys-polled",
+					      PLATFORM_DEVID_NONE,
+					      &keys_pdata, sizeof(keys_pdata));
+
+	if (IS_ERR(p50->keys_pdev)) {
+		ret = PTR_ERR(p50->keys_pdev);
+		dev_err(&pdev->dev, "Could not register gpio-keys-polled: %d\n", ret);
+		goto err_keys;
+	}
+
+	return 0;
+
+err_keys:
+	platform_device_unregister(p50->leds_pdev);
+err_leds:
+	gpiod_remove_lookup_table(&p50_gpio_led_table);
+
+	return ret;
+}
+
+static int p50_gpio_remove(struct platform_device *pdev)
+{
+	struct p50_gpio *p50 = platform_get_drvdata(pdev);
+
+	platform_device_unregister(p50->keys_pdev);
+	platform_device_unregister(p50->leds_pdev);
+
+	gpiod_remove_lookup_table(&p50_gpio_led_table);
+
+	return 0;
+}
+
+static struct platform_driver p50_gpio_driver = {
+	.driver = {
+		.name = DRIVER_NAME,
+	},
+	.probe = p50_gpio_probe,
+	.remove = p50_gpio_remove,
+};
+
+/* Board setup */
+static const struct dmi_system_id dmi_ids[] __initconst = {
+	{
+		.matches = {
+			DMI_EXACT_MATCH(DMI_SYS_VENDOR, "Barco"),
+			DMI_EXACT_MATCH(DMI_PRODUCT_FAMILY, "P50")
+		},
+	},
+	{}
+};
+MODULE_DEVICE_TABLE(dmi, dmi_ids);
+
+static int __init p50_module_init(void)
+{
+	struct resource res = DEFINE_RES_IO(P50_GPIO_IO_PORT_BASE, P50_PORT_CMD + 1);
+
+	if (!dmi_first_match(dmi_ids))
+		return -ENODEV;
+
+	platform_driver_register(&p50_gpio_driver);
+
+	gpio_pdev = platform_device_register_simple(DRIVER_NAME, PLATFORM_DEVID_NONE, &res, 1);
+	if (IS_ERR(gpio_pdev)) {
+		pr_err("failed registering %s: %ld\n", DRIVER_NAME, PTR_ERR(gpio_pdev));
+		platform_driver_unregister(&p50_gpio_driver);
+		return PTR_ERR(gpio_pdev);
+	}
+
+	return 0;
+}
+
+static void __exit p50_module_exit(void)
+{
+	platform_device_unregister(gpio_pdev);
+	platform_driver_unregister(&p50_gpio_driver);
+}
+
+module_init(p50_module_init);
+module_exit(p50_module_exit);
+
+MODULE_AUTHOR("Santosh Kumar Yadav, Barco NV <santoshkumar.yadav@barco.com>");
+MODULE_DESCRIPTION("Barco P50 identify GPIOs driver");
+MODULE_LICENSE("GPL");