platform/surface: Move Surface 3 Button driver to platform/surface

Move the Surface 3 Button driver from platform/x86 to the newly created
platform/surface directory.

Signed-off-by: Maximilian Luz <luzmaximilian@gmail.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Link: https://lore.kernel.org/r/20201009141128.683254-4-luzmaximilian@gmail.com
Signed-off-by: Hans de Goede <hdegoede@redhat.com>

3 files changed, 254 insertions, 0 deletions

diff --git a/drivers/platform/surface/Kconfig b/drivers/platform/surface/Kconfig
index 326f7bbf83d7..1a7cf6a73d52 100644
--- a/drivers/platform/surface/Kconfig
+++ b/drivers/platform/surface/Kconfig
@@ -27,4 +27,10 @@ config SURFACE3_WMI
 	  To compile this driver as a module, choose M here: the module will
 	  be called surface3-wmi.
 
+config SURFACE_3_BUTTON
+	tristate "Power/home/volume buttons driver for Microsoft Surface 3 tablet"
+	depends on ACPI && KEYBOARD_GPIO && I2C
+	help
+	  This driver handles the power/home/volume buttons on the Microsoft Surface 3 tablet.
+
 endif # SURFACE_PLATFORMS
diff --git a/drivers/platform/surface/Makefile b/drivers/platform/surface/Makefile
index f889d521420f..8588dc178245 100644
--- a/drivers/platform/surface/Makefile
+++ b/drivers/platform/surface/Makefile
@@ -5,3 +5,4 @@
 #
 
 obj-$(CONFIG_SURFACE3_WMI)		+= surface3-wmi.o
+obj-$(CONFIG_SURFACE_3_BUTTON)		+= surface3_button.o
diff --git a/drivers/platform/surface/surface3_button.c b/drivers/platform/surface/surface3_button.c
new file mode 100644
index 000000000000..48d77e7aae76
--- /dev/null
+++ b/drivers/platform/surface/surface3_button.c
@@ -0,0 +1,247 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Supports for the button array on the Surface tablets.
+ *
+ * (C) Copyright 2016 Red Hat, Inc
+ *
+ * Based on soc_button_array.c:
+ *
+ * {C} Copyright 2014 Intel Corporation
+ */
+
+#include <linux/module.h>
+#include <linux/input.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/i2c.h>
+#include <linux/slab.h>
+#include <linux/acpi.h>
+#include <linux/gpio/consumer.h>
+#include <linux/gpio_keys.h>
+#include <linux/gpio.h>
+#include <linux/platform_device.h>
+
+
+#define SURFACE_BUTTON_OBJ_NAME		"TEV2"
+#define MAX_NBUTTONS			4
+
+/*
+ * Some of the buttons like volume up/down are auto repeat, while others
+ * are not. To support both, we register two platform devices, and put
+ * buttons into them based on whether the key should be auto repeat.
+ */
+#define BUTTON_TYPES			2
+
+/*
+ * Power button, Home button, Volume buttons support is supposed to
+ * be covered by drivers/input/misc/soc_button_array.c, which is implemented
+ * according to "Windows ACPI Design Guide for SoC Platforms".
+ * However surface 3 seems not to obey the specs, instead it uses
+ * device TEV2(MSHW0028) for declaring the GPIOs. The gpios are also slightly
+ * different in which the Home button is active high.
+ * Compared to surfacepro3_button.c which also handles MSHW0028, the Surface 3
+ * is a reduce platform and thus uses GPIOs, not ACPI events.
+ * We choose an I2C driver here because we need to access the resources
+ * declared under the device node, while surfacepro3_button.c only needs
+ * the ACPI companion node.
+ */
+static const struct acpi_device_id surface3_acpi_match[] = {
+	{ "MSHW0028", 0 },
+	{ }
+};
+MODULE_DEVICE_TABLE(acpi, surface3_acpi_match);
+
+struct surface3_button_info {
+	const char *name;
+	int acpi_index;
+	unsigned int event_type;
+	unsigned int event_code;
+	bool autorepeat;
+	bool wakeup;
+	bool active_low;
+};
+
+struct surface3_button_data {
+	struct platform_device *children[BUTTON_TYPES];
+};
+
+/*
+ * Get the Nth GPIO number from the ACPI object.
+ */
+static int surface3_button_lookup_gpio(struct device *dev, int acpi_index)
+{
+	struct gpio_desc *desc;
+	int gpio;
+
+	desc = gpiod_get_index(dev, NULL, acpi_index, GPIOD_ASIS);
+	if (IS_ERR(desc))
+		return PTR_ERR(desc);
+
+	gpio = desc_to_gpio(desc);
+
+	gpiod_put(desc);
+
+	return gpio;
+}
+
+static struct platform_device *
+surface3_button_device_create(struct i2c_client *client,
+			      const struct surface3_button_info *button_info,
+			      bool autorepeat)
+{
+	const struct surface3_button_info *info;
+	struct platform_device *pd;
+	struct gpio_keys_button *gpio_keys;
+	struct gpio_keys_platform_data *gpio_keys_pdata;
+	int n_buttons = 0;
+	int gpio;
+	int error;
+
+	gpio_keys_pdata = devm_kzalloc(&client->dev,
+				       sizeof(*gpio_keys_pdata) +
+				       sizeof(*gpio_keys) * MAX_NBUTTONS,
+				       GFP_KERNEL);
+	if (!gpio_keys_pdata)
+		return ERR_PTR(-ENOMEM);
+
+	gpio_keys = (void *)(gpio_keys_pdata + 1);
+
+	for (info = button_info; info->name; info++) {
+		if (info->autorepeat != autorepeat)
+			continue;
+
+		gpio = surface3_button_lookup_gpio(&client->dev,
+						   info->acpi_index);
+		if (!gpio_is_valid(gpio))
+			continue;
+
+		gpio_keys[n_buttons].type = info->event_type;
+		gpio_keys[n_buttons].code = info->event_code;
+		gpio_keys[n_buttons].gpio = gpio;
+		gpio_keys[n_buttons].active_low = info->active_low;
+		gpio_keys[n_buttons].desc = info->name;
+		gpio_keys[n_buttons].wakeup = info->wakeup;
+		n_buttons++;
+	}
+
+	if (n_buttons == 0) {
+		error = -ENODEV;
+		goto err_free_mem;
+	}
+
+	gpio_keys_pdata->buttons = gpio_keys;
+	gpio_keys_pdata->nbuttons = n_buttons;
+	gpio_keys_pdata->rep = autorepeat;
+
+	pd = platform_device_alloc("gpio-keys", PLATFORM_DEVID_AUTO);
+	if (!pd) {
+		error = -ENOMEM;
+		goto err_free_mem;
+	}
+
+	error = platform_device_add_data(pd, gpio_keys_pdata,
+					 sizeof(*gpio_keys_pdata));
+	if (error)
+		goto err_free_pdev;
+
+	error = platform_device_add(pd);
+	if (error)
+		goto err_free_pdev;
+
+	return pd;
+
+err_free_pdev:
+	platform_device_put(pd);
+err_free_mem:
+	devm_kfree(&client->dev, gpio_keys_pdata);
+	return ERR_PTR(error);
+}
+
+static int surface3_button_remove(struct i2c_client *client)
+{
+	struct surface3_button_data *priv = i2c_get_clientdata(client);
+
+	int i;
+
+	for (i = 0; i < BUTTON_TYPES; i++)
+		if (priv->children[i])
+			platform_device_unregister(priv->children[i]);
+
+	return 0;
+}
+
+static struct surface3_button_info surface3_button_surface3[] = {
+	{ "power", 0, EV_KEY, KEY_POWER, false, true, true },
+	{ "home", 1, EV_KEY, KEY_LEFTMETA, false, true, false },
+	{ "volume_up", 2, EV_KEY, KEY_VOLUMEUP, true, false, true },
+	{ "volume_down", 3, EV_KEY, KEY_VOLUMEDOWN, true, false, true },
+	{ }
+};
+
+static int surface3_button_probe(struct i2c_client *client,
+				 const struct i2c_device_id *id)
+{
+	struct device *dev = &client->dev;
+	struct surface3_button_data *priv;
+	struct platform_device *pd;
+	int i;
+	int error;
+
+	if (strncmp(acpi_device_bid(ACPI_COMPANION(&client->dev)),
+		    SURFACE_BUTTON_OBJ_NAME,
+		    strlen(SURFACE_BUTTON_OBJ_NAME)))
+		return -ENODEV;
+
+	error = gpiod_count(dev, NULL);
+	if (error < 0) {
+		dev_dbg(dev, "no GPIO attached, ignoring...\n");
+		return error;
+	}
+
+	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+
+	i2c_set_clientdata(client, priv);
+
+	for (i = 0; i < BUTTON_TYPES; i++) {
+		pd = surface3_button_device_create(client,
+						   surface3_button_surface3,
+						   i == 0);
+		if (IS_ERR(pd)) {
+			error = PTR_ERR(pd);
+			if (error != -ENODEV) {
+				surface3_button_remove(client);
+				return error;
+			}
+			continue;
+		}
+
+		priv->children[i] = pd;
+	}
+
+	if (!priv->children[0] && !priv->children[1])
+		return -ENODEV;
+
+	return 0;
+}
+
+static const struct i2c_device_id surface3_id[] = {
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, surface3_id);
+
+static struct i2c_driver surface3_driver = {
+	.probe = surface3_button_probe,
+	.remove = surface3_button_remove,
+	.id_table = surface3_id,
+	.driver = {
+		.name = "surface3",
+		.acpi_match_table = ACPI_PTR(surface3_acpi_match),
+	},
+};
+module_i2c_driver(surface3_driver);
+
+MODULE_AUTHOR("Benjamin Tissoires <benjamin.tissoires@gmail.com>");
+MODULE_DESCRIPTION("surface3 button array driver");
+MODULE_LICENSE("GPL v2");