linux-kernel - [PATCH] i2c: i801: Register optional lis3lv02d i2c device on Dell machines

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Message-Id: <1482843136-12838-1-git-send-email-pali.rohar@gmail.com>
Date:   Tue, 27 Dec 2016 13:52:16 +0100
From:   Pali Rohár <pali.rohar@...il.com>
To:     Jean Delvare <jdelvare@...e.com>, Wolfram Sang <wsa@...-dreams.de>,
        Steven Honeyman <stevenhoneyman@...il.com>,
        Valdis.Kletnieks@...edu,
        Jochen Eisinger <jochen@...guin-breeder.org>,
        Gabriele Mazzotta <gabriele.mzt@...il.com>,
        Andy Lutomirski <luto@...nel.org>, Mario_Limonciello@...l.com,
        Alex Hung <alex.hung@...onical.com>,
        Michał Kępień <kernel@...pniu.pl>,
        Takashi Iwai <tiwai@...e.de>
Cc:     linux-i2c@...r.kernel.org, linux-kernel@...r.kernel.org,
        platform-driver-x86@...r.kernel.org,
        Pali Rohár <pali.rohar@...il.com>
Subject: [PATCH] i2c: i801: Register optional lis3lv02d i2c device on Dell machines

Dell platform team told us that some (DMI whitelisted) Dell Latitude
machines have ST microelectronics accelerometer at i2c address 0x29. That
i2c address is not specified in DMI or ACPI, so runtime detection without
whitelist which is below is not possible.

Presence of that ST microelectronics accelerometer is verified by existence
of SMO88xx ACPI device which represent that accelerometer. Unfortunately
without i2c address.

This patch registers lis3lv02d device at i2c address 0x29 if is detected.

Finally commit a7ae81952cda ("i2c: i801: Allow ACPI SystemIO OpRegion to
conflict with PCI BAR") allowed to use i2c-i801 driver on Dell machines so
lis3lv02d correctly initialize accelerometer.

Tested on Dell Latitude E6440.

Signed-off-by: Pali Rohár <pali.rohar@...il.com>
---
 drivers/i2c/busses/i2c-i801.c |   98 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 98 insertions(+)

diff --git a/drivers/i2c/busses/i2c-i801.c b/drivers/i2c/busses/i2c-i801.c
index eb3627f..188cfd4 100644
--- a/drivers/i2c/busses/i2c-i801.c
+++ b/drivers/i2c/busses/i2c-i801.c
@@ -1118,6 +1118,101 @@ static void dmi_check_onboard_devices(const struct dmi_header *dm, void *adap)
 	}
 }
 
+static acpi_status check_acpi_smo88xx_device(acpi_handle obj_handle,
+					     u32 nesting_level,
+					     void *context,
+					     void **return_value)
+{
+	struct acpi_device_info *info;
+	acpi_status status;
+	char *hid;
+
+	status = acpi_get_object_info(obj_handle, &info);
+	if (!ACPI_SUCCESS(status) || !(info->valid & ACPI_VALID_HID))
+		return AE_OK;
+
+	hid = info->hardware_id.string;
+	if (!hid)
+		return AE_OK;
+
+	if (strlen(hid) < 7)
+		return AE_OK;
+
+	if (memcmp(hid, "SMO88", 5) != 0)
+		return AE_OK;
+
+	*((bool *)return_value) = true;
+	return AE_CTRL_TERMINATE;
+}
+
+static bool is_dell_system_with_lis3lv02d(void)
+{
+	bool found;
+	acpi_status status;
+	const char *vendor;
+
+	vendor = dmi_get_system_info(DMI_SYS_VENDOR);
+	if (strcmp(vendor, "Dell Inc.") != 0)
+		return false;
+
+	/*
+	 * Check if ACPI device SMO88xx exists and if is enabled. That ACPI
+	 * device represent our ST microelectronics lis3lv02d accelerometer but
+	 * unfortunately without any other additional information.
+	 */
+	found = false;
+	status = acpi_get_devices(NULL, check_acpi_smo88xx_device, NULL,
+				  (void **)&found);
+	if (!ACPI_SUCCESS(status) || !found)
+		return false;
+
+	return true;
+}
+
+/*
+ * Dell platform team told us that these Latitude devices have
+ * ST microelectronics accelerometer at i2c address 0x29.
+ * That i2c address is not specified in DMI or ACPI, so runtime
+ * detection without whitelist which is below is not possible.
+ */
+static const char * const dmi_dell_product_names[] = {
+	"Latitude E5250",
+	"Latitude E5450",
+	"Latitude E5550",
+	"Latitude E6440",
+	"Latitude E6440 ATG",
+	"Latitude E6540",
+};
+
+static void register_dell_lis3lv02d_i2c_device(struct i801_priv *priv)
+{
+	struct i2c_board_info info;
+	const char *product_name;
+	bool known_i2c_address;
+	int i;
+
+	known_i2c_address = false;
+	product_name = dmi_get_system_info(DMI_PRODUCT_NAME);
+	for (i = 0; i < ARRAY_SIZE(dmi_dell_product_names); ++i) {
+		if (strcmp(product_name, dmi_dell_product_names[i]) == 0) {
+			known_i2c_address = true;
+			break;
+		}
+	}
+
+	if (!known_i2c_address) {
+		dev_warn(&priv->pci_dev->dev,
+			 "Accelerometer lis3lv02d i2c device is present "
+			 "but its i2c address is unknown, skipping ...\n");
+		return;
+	}
+
+	memset(&info, 0, sizeof(struct i2c_board_info));
+	info.addr = 0x29;
+	strlcpy(info.type, "lis3lv02d", I2C_NAME_SIZE);
+	i2c_new_device(&priv->adapter, &info);
+}
+
 /* Register optional slaves */
 static void i801_probe_optional_slaves(struct i801_priv *priv)
 {
@@ -1136,6 +1231,9 @@ static void i801_probe_optional_slaves(struct i801_priv *priv)
 
 	if (dmi_name_in_vendors("FUJITSU"))
 		dmi_walk(dmi_check_onboard_devices, &priv->adapter);
+
+	if (is_dell_system_with_lis3lv02d())
+		register_dell_lis3lv02d_i2c_device(priv);
 }
 #else
 static void __init input_apanel_init(void) {}
-- 
1.7.9.5