Add the function pmbus_read_coefficients to pmbus_core to be able to
read and decode the coefficients for the direct format for a certain
command.

Signed-off-by: Erik Rosen <redacted>
---
  drivers/hwmon/pmbus/pmbus.h      |  4 ++++
  drivers/hwmon/pmbus/pmbus_core.c | 38 ++++++++++++++++++++++++++++++++
  2 files changed, 42 insertions(+)

diff --git a/drivers/hwmon/pmbus/pmbus.h b/drivers/hwmon/pmbus/pmbus.h
index 3968924f8533..d9ed9736b480 100644
--- a/drivers/hwmon/pmbus/pmbus.h
+++ b/drivers/hwmon/pmbus/pmbus.h

@@ -499,6 +499,10 @@ int pmbus_get_fan_rate_cached(struct i2c_client *client, int page, int id,
  			      enum pmbus_fan_mode mode);
  int pmbus_update_fan(struct i2c_client *client, int page, int id,
  		     u8 config, u8 mask, u16 command);
+int pmbus_read_coefficients(struct i2c_client *client,
+			    struct pmbus_driver_info *info,
+			    enum pmbus_sensor_classes sensor_class,
+			    u8 command);
  struct dentry *pmbus_get_debugfs_dir(struct i2c_client *client);
  
  #endif /* PMBUS_H */

diff --git a/drivers/hwmon/pmbus/pmbus_core.c b/drivers/hwmon/pmbus/pmbus_core.c
index cb885efc4fba..460cbfd716e4 100644
--- a/drivers/hwmon/pmbus/pmbus_core.c
+++ b/drivers/hwmon/pmbus/pmbus_core.c

@@ -301,6 +301,44 @@ int pmbus_update_fan(struct i2c_client *client, int page, int id,
  }
  EXPORT_SYMBOL_NS_GPL(pmbus_update_fan, PMBUS);
  
+/*
+ * Read the coefficients for direct mode.
+ */
+int pmbus_read_coefficients(struct i2c_client *client,
+			    struct pmbus_driver_info *info,
+			    enum pmbus_sensor_classes sensor_class,
+			    u8 command)
+{
+	int rv;
+	union i2c_smbus_data data;
+	s8 R;
+	s16 m, b;
+
+	data.block[0] = 2;
+	data.block[1] = command;
+	data.block[2] = 0x01;
+
+	rv = i2c_smbus_xfer(client->adapter, client->addr, client->flags,
+			    I2C_SMBUS_WRITE, PMBUS_COEFFICIENTS,
+			    I2C_SMBUS_BLOCK_PROC_CALL, &data);
+
+	if (rv < 0)
+		return rv;
+
+	if (data.block[0] != 5)
+		return -EIO;
+
+	m = data.block[1] | (data.block[2] << 8);
+	b = data.block[3] | (data.block[4] << 8);
+	R = data.block[5];
+	info->m[sensor_class] = m;
+	info->b[sensor_class] = b;
+	info->R[sensor_class] = R;
+
+	return rv;
+}
+EXPORT_SYMBOL_NS_GPL(pmbus_read_coefficients, PMBUS);