[PATCH v4 5/6] 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.

Signed-off-by: Andrew Jeffery <and...@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 cdf3e288e626..0560a8dbcee0 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, vr13 };
 
diff --git a/drivers/hwmon/pmbus/pmbus_core.c b/drivers/hwmon/pmbus/pmbus_core.c
index 55838b69e99a..af7362de405d 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