Input: atmel_mxt_ts - add support for Google Pixel 2

This change allows atmel_mxt_ts to bind to ACPI-enumerated devices in
Google Pixel 2 (2015).

While newer version of ACPI standard allow use of device-tree-like
properties in device descriptions, the version of ACPI implemented in
Google BIOS does not support them, and we have to resort to DMI data to
specify exact characteristics of the devices (touchpad vs. touchscreen,
GPIO to button mapping, etc).

Pixel 1 continues to use i2c devices and platform data created by
chromeos-laptop driver, since ACPI does not enumerate them.

Reviewed-by: Javier Martinez Canillas <javier.martinez@collabora.co.uk>
Tested-by: Javier Martinez Canillas <javier.martinez@collabora.co.uk>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

drivers/input/touchscreen/atmel_mxt_ts.c

@@ -14,6 +14,8 @@
  *
  */
 
+#include <linux/acpi.h>
+#include <linux/dmi.h>
 #include <linux/module.h>
 #include <linux/init.h>
 #include <linux/completion.h>
@@ -2371,15 +2373,15 @@ static void mxt_input_close(struct input_dev *dev)
 }
 
 #ifdef CONFIG_OF
-static struct mxt_platform_data *mxt_parse_dt(struct i2c_client *client)
+static const struct mxt_platform_data *mxt_parse_dt(struct i2c_client *client)
 {
 	struct mxt_platform_data *pdata;
 	u32 *keymap;
 	u32 keycode;
 	int proplen, i, ret;
 
 	if (!client->dev.of_node)
-		return ERR_PTR(-ENODEV);
+		return ERR_PTR(-ENOENT);
 
 	pdata = devm_kzalloc(&client->dev, sizeof(*pdata), GFP_KERNEL);
 	if (!pdata)
@@ -2410,25 +2412,132 @@ static struct mxt_platform_data *mxt_parse_dt(struct i2c_client *client)
 	return pdata;
 }
 #else
-static struct mxt_platform_data *mxt_parse_dt(struct i2c_client *client)
+static const struct mxt_platform_data *mxt_parse_dt(struct i2c_client *client)
 {
-	dev_dbg(&client->dev, "No platform data specified\n");
-	return ERR_PTR(-EINVAL);
+	return ERR_PTR(-ENOENT);
+}
+#endif
+
+#ifdef CONFIG_ACPI
+
+struct mxt_acpi_platform_data {
+	const char *hid;
+	struct mxt_platform_data pdata;
+};
+
+static unsigned int samus_touchpad_buttons[] = {
+	KEY_RESERVED,
+	KEY_RESERVED,
+	KEY_RESERVED,
+	BTN_LEFT
+};
+
+static struct mxt_acpi_platform_data samus_platform_data[] = {
+	{
+		/* Touchpad */
+		.hid	= "ATML0000",
+		.pdata	= {
+			.t19_num_keys	= ARRAY_SIZE(samus_touchpad_buttons),
+			.t19_keymap	= samus_touchpad_buttons,
+		},
+	},
+	{
+		/* Touchscreen */
+		.hid	= "ATML0001",
+	},
+	{ }
+};
+
+static const struct dmi_system_id mxt_dmi_table[] = {
+	{
+		/* 2015 Google Pixel */
+		.ident = "Chromebook Pixel 2",
+		.matches = {
+			DMI_MATCH(DMI_SYS_VENDOR, "GOOGLE"),
+			DMI_MATCH(DMI_PRODUCT_NAME, "Samus"),
+		},
+		.driver_data = samus_platform_data,
+	},
+	{ }
+};
+
+static const struct mxt_platform_data *mxt_parse_acpi(struct i2c_client *client)
+{
+	struct acpi_device *adev;
+	const struct dmi_system_id *system_id;
+	const struct mxt_acpi_platform_data *acpi_pdata;
+
+	/*
+	 * Ignore ACPI devices representing bootloader mode.
+	 *
+	 * This is a bit of a hack: Google Chromebook BIOS creates ACPI
+	 * devices for both application and bootloader modes, but we are
+	 * interested in application mode only (if device is in bootloader
+	 * mode we'll end up switching into application anyway). So far
+	 * application mode addresses were all above 0x40, so we'll use it
+	 * as a threshold.
+	 */
+	if (client->addr < 0x40)
+		return ERR_PTR(-ENXIO);
+
+	adev = ACPI_COMPANION(&client->dev);
+	if (!adev)
+		return ERR_PTR(-ENOENT);
+
+	system_id = dmi_first_match(mxt_dmi_table);
+	if (!system_id)
+		return ERR_PTR(-ENOENT);
+
+	acpi_pdata = system_id->driver_data;
+	if (!acpi_pdata)
+		return ERR_PTR(-ENOENT);
+
+	while (acpi_pdata->hid) {
+		if (!strcmp(acpi_device_hid(adev), acpi_pdata->hid))
+			return &acpi_pdata->pdata;
+
+		acpi_pdata++;
+	}
+
+	return ERR_PTR(-ENOENT);
+}
+#else
+static const struct mxt_platform_data *mxt_parse_acpi(struct i2c_client *client)
+{
+	return ERR_PTR(-ENOENT);
 }
 #endif
 
+static const struct mxt_platform_data *
+mxt_get_platform_data(struct i2c_client *client)
+{
+	const struct mxt_platform_data *pdata;
+
+	pdata = dev_get_platdata(&client->dev);
+	if (pdata)
+		return pdata;
+
+	pdata = mxt_parse_dt(client);
+	if (!IS_ERR(pdata) || PTR_ERR(pdata) != -ENOENT)
+		return pdata;
+
+	pdata = mxt_parse_acpi(client);
+	if (!IS_ERR(pdata) || PTR_ERR(pdata) != -ENOENT)
+		return pdata;
+
+	dev_err(&client->dev, "No platform data specified\n");
+	return ERR_PTR(-EINVAL);
+}
+
 static int mxt_probe(struct i2c_client *client, const struct i2c_device_id *id)
 {
 	struct mxt_data *data;
 	const struct mxt_platform_data *pdata;
 	int error;
 
-	pdata = dev_get_platdata(&client->dev);
-	if (!pdata) {
-		pdata = mxt_parse_dt(client);
-		if (IS_ERR(pdata))
-			return PTR_ERR(pdata);
-	}
+	pdata = mxt_get_platform_data(client);
+	if (IS_ERR(pdata))
+		return PTR_ERR(pdata);
 
 	data = kzalloc(sizeof(struct mxt_data), GFP_KERNEL);
 	if (!data) {
@@ -2536,6 +2645,15 @@ static const struct of_device_id mxt_of_match[] = {
 };
 MODULE_DEVICE_TABLE(of, mxt_of_match);
 
+#ifdef CONFIG_ACPI
+static const struct acpi_device_id mxt_acpi_id[] = {
+	{ "ATML0000", 0 },	/* Touchpad */
+	{ "ATML0001", 0 },	/* Touchscreen */
+	{ }
+};
+MODULE_DEVICE_TABLE(acpi, mxt_acpi_id);
+#endif
+
 static const struct i2c_device_id mxt_id[] = {
 	{ "qt602240_ts", 0 },
 	{ "atmel_mxt_ts", 0 },
@@ -2550,6 +2668,7 @@ static struct i2c_driver mxt_driver = {
 		.name	= "atmel_mxt_ts",
 		.owner	= THIS_MODULE,
 		.of_match_table = of_match_ptr(mxt_of_match),
+		.acpi_match_table = ACPI_PTR(mxt_acpi_id),
 		.pm	= &mxt_pm_ops,
 	},
 	.probe		= mxt_probe,