[PATCH linux dev-4.10 1/3] hwmon: pmbus: core: Add virtual page config bit

[Andrew Jeffery]

Some circumstances call for virtual pages to expose multiple values
packed into an extended PMBus register in a manner non-compliant with
the PMBus standard. We should not try to set virtual pages on the
device; add a flag so we can avoid doing so.

Cc: Eddie James <eajames at linux.vnet.ibm.com>
Cc: Matt Spinler <mspinler at linux.vnet.ibm.com>
Signed-off-by: Andrew Jeffery <andrew at aj.id.au>
---
 drivers/hwmon/pmbus/pmbus.h      |  2 ++
 drivers/hwmon/pmbus/pmbus_core.c | 12 ++++++++----
 2 files changed, 10 insertions(+), 4 deletions(-)

diff --git a/drivers/hwmon/pmbus/pmbus.h b/drivers/hwmon/pmbus/pmbus.h
index a863b8fed16f..fd422cd76452 100644
--- a/drivers/hwmon/pmbus/pmbus.h
+++ b/drivers/hwmon/pmbus/pmbus.h
@@ -367,6 +367,8 @@ enum pmbus_sensor_classes {
 #define PMBUS_HAVE_PWM12	BIT(20)
 #define PMBUS_HAVE_PWM34	BIT(21)
 
+#define PMBUS_PAGE_VIRTUAL	BIT(31)
+
 enum pmbus_data_format { linear = 0, direct, vid };
 enum vrm_version { vr11 = 0, vr12 };
 
diff --git a/drivers/hwmon/pmbus/pmbus_core.c b/drivers/hwmon/pmbus/pmbus_core.c
index f72f966f5251..390a7b02b836 100644
--- a/drivers/hwmon/pmbus/pmbus_core.c
+++ b/drivers/hwmon/pmbus/pmbus_core.c
@@ -164,14 +164,18 @@ int pmbus_set_page(struct i2c_client *client, u8 page)
 	int rv = 0;
 	int newpage;
 
-	if (page != data->currpage) {
+	if (page == data->currpage)
+		return 0;
+
+	if (!(data->info->func[page] & PMBUS_PAGE_VIRTUAL)) {
 		rv = i2c_smbus_write_byte_data(client, PMBUS_PAGE, page);
 		newpage = i2c_smbus_read_byte_data(client, PMBUS_PAGE);
 		if (newpage != page)
-			rv = -EIO;
-		else
-			data->currpage = page;
+			return -EIO;
 	}
+
+	data->currpage = page;
+
 	return rv;
 }
 EXPORT_SYMBOL_GPL(pmbus_set_page);
-- 
2.11.0