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Date:   Sat,  2 Sep 2017 18:20:40 +0200
From:   Hans de Goede <hdegoede@...hat.com>
To:     "Rafael J . Wysocki" <rjw@...ysocki.net>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Darren Hart <dvhart@...radead.org>,
        Andy Shevchenko <andy@...radead.org>
Cc:     Hans de Goede <hdegoede@...hat.com>, linux-acpi@...r.kernel.org,
        platform-driver-x86@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH v2] platform/x86: intel_cht_int33fe: Work around BIOS bug on some devices

At least one BIOS enumerates the max17047 both through the INT33FE ACPI
device (it is right there in the resources table) as well as through a
separate MAX17047 device.

This commit checks for the max17047 already being enumerated through
a separate MAX17047 ACPI device and if so it uses the i2c-client
instantiated for this and attaches the device-props for the max17047 to
that i2c-client.

Signed-off-by: Hans de Goede <hdegoede@...hat.com>
---
Changes in v2:
-Check acpi_companion HID instead of dev_name
---
 drivers/platform/x86/intel_cht_int33fe.c | 71 +++++++++++++++++++++++++++-----
 1 file changed, 61 insertions(+), 10 deletions(-)

diff --git a/drivers/platform/x86/intel_cht_int33fe.c b/drivers/platform/x86/intel_cht_int33fe.c
index da706e2c4232..a9cbc4b8ca63 100644
--- a/drivers/platform/x86/intel_cht_int33fe.c
+++ b/drivers/platform/x86/intel_cht_int33fe.c
@@ -34,6 +34,42 @@ struct cht_int33fe_data {
 	struct i2c_client *pi3usb30532;
 };
 
+/*
+ * Grrr I severly dislike buggy BIOS-es. At least one BIOS enumerates
+ * the max17047 both through the INT33FE ACPI device (it is right there
+ * in the resources table) as well as through a separate MAX17047 device.
+ *
+ * These helpers are used to work around this by checking if an i2c-client
+ * for the max17047 has already been registered.
+ */
+int cht_int33fe_check_for_max17047(struct device *dev, void *data)
+{
+	struct acpi_device *companion = ACPI_COMPANION(dev);
+	struct i2c_client **max17047 = data;
+	const char *hid;
+
+	if (!companion)
+		return 0;
+
+	hid = acpi_device_hid(companion);
+
+	/* The MAX17047 ACPI node doesn't have an UID, so we don't check that */
+	if (strcmp(hid, "MAX17047") == 0) {
+		*max17047 = to_i2c_client(dev);
+		return 1;
+	}
+
+	return 0;
+}
+
+struct i2c_client *cht_int33fe_find_max17047(void)
+{
+	struct i2c_client *max17047 = NULL;
+
+	i2c_for_each_dev(&max17047, cht_int33fe_check_for_max17047);
+	return max17047;
+}
+
 static const char * const max17047_suppliers[] = { "bq24190-charger" };
 
 static const struct property_entry max17047_props[] = {
@@ -46,9 +82,10 @@ static int cht_int33fe_probe(struct i2c_client *client)
 	struct device *dev = &client->dev;
 	struct i2c_board_info board_info;
 	struct cht_int33fe_data *data;
+	struct i2c_client *max17047;
 	unsigned long long ptyp;
 	acpi_status status;
-	int fusb302_irq;
+	int ret, fusb302_irq;
 
 	status = acpi_evaluate_integer(ACPI_HANDLE(dev), "PTYP", NULL, &ptyp);
 	if (ACPI_FAILURE(status)) {
@@ -75,13 +112,25 @@ static int cht_int33fe_probe(struct i2c_client *client)
 	if (!data)
 		return -ENOMEM;
 
-	memset(&board_info, 0, sizeof(board_info));
-	strlcpy(board_info.type, "max17047", I2C_NAME_SIZE);
-	board_info.properties = max17047_props;
-
-	data->max17047 = i2c_acpi_new_device(dev, 1, &board_info);
-	if (!data->max17047)
-		return -EPROBE_DEFER; /* Wait for the i2c-adapter to load */
+	/* Work around BIOS bug, see comment on cht_int33fe_find_max17047 */
+	max17047 = cht_int33fe_find_max17047();
+	if (max17047) {
+		/* Pre-existing i2c-client for the max17047, add device-props */
+		ret = device_add_properties(&max17047->dev, max17047_props);
+		if (ret)
+			return ret;
+		/* And re-probe to get the new device-props applied. */
+		ret = device_reprobe(&max17047->dev);
+		if (ret)
+			dev_warn(dev, "Reprobing max17047 error: %d\n", ret);
+	} else {
+		memset(&board_info, 0, sizeof(board_info));
+		strlcpy(board_info.type, "max17047", I2C_NAME_SIZE);
+		board_info.properties = max17047_props;
+		data->max17047 = i2c_acpi_new_device(dev, 1, &board_info);
+		if (!data->max17047)
+			return -EPROBE_DEFER; /* Wait for i2c-adapter to load */
+	}
 
 	memset(&board_info, 0, sizeof(board_info));
 	strlcpy(board_info.type, "fusb302", I2C_NAME_SIZE);
@@ -106,7 +155,8 @@ static int cht_int33fe_probe(struct i2c_client *client)
 	i2c_unregister_device(data->fusb302);
 
 out_unregister_max17047:
-	i2c_unregister_device(data->max17047);
+	if (data->max17047)
+		i2c_unregister_device(data->max17047);
 
 	return -EPROBE_DEFER; /* Wait for the i2c-adapter to load */
 }
@@ -117,7 +167,8 @@ static int cht_int33fe_remove(struct i2c_client *i2c)
 
 	i2c_unregister_device(data->pi3usb30532);
 	i2c_unregister_device(data->fusb302);
-	i2c_unregister_device(data->max17047);
+	if (data->max17047)
+		i2c_unregister_device(data->max17047);
 
 	return 0;
 }
-- 
2.13.4

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