hwmon: (pmbus) Add support for reading direct mode coefficients

Add support for reading and decoding direct format coefficients to
the PMBus core driver. If the new flag PMBUS_USE_COEFFICIENTS_CMD
is set, the driver will use the COEFFICIENTS register together with
the information in the pmbus_sensor_attr structs to initialize
relevant coefficients for the direct mode format.

Signed-off-by: Erik Rosen <erik.rosen@metormote.com>
[groeck: Initialize ret with -EINVAL in pmbus_init_coefficients()]
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

diff --git a/drivers/hwmon/pmbus/pmbus_core.c b/drivers/hwmon/pmbus/pmbus_core.c
index a5367df..c4f557c 100644 (file)
--- a/drivers/hwmon/pmbus/pmbus_core.c
+++ b/drivers/hwmon/pmbus/pmbus_core.c
@@ -2142,6 +2142,111 @@ static int pmbus_find_attributes(struct i2c_client *client,
 }
 
 /*
+ * The pmbus_class_attr_map structure maps one sensor class to
+ * it's corresponding sensor attributes array.
+ */
+struct pmbus_class_attr_map {
+       enum pmbus_sensor_classes class;
+       int nattr;
+       const struct pmbus_sensor_attr *attr;
+};
+
+static const struct pmbus_class_attr_map class_attr_map[] = {
+       {
+               .class = PSC_VOLTAGE_IN,
+               .attr = voltage_attributes,
+               .nattr = ARRAY_SIZE(voltage_attributes),
+       }, {
+               .class = PSC_VOLTAGE_OUT,
+               .attr = voltage_attributes,
+               .nattr = ARRAY_SIZE(voltage_attributes),
+       }, {
+               .class = PSC_CURRENT_IN,
+               .attr = current_attributes,
+               .nattr = ARRAY_SIZE(current_attributes),
+       }, {
+               .class = PSC_CURRENT_OUT,
+               .attr = current_attributes,
+               .nattr = ARRAY_SIZE(current_attributes),
+       }, {
+               .class = PSC_POWER,
+               .attr = power_attributes,
+               .nattr = ARRAY_SIZE(power_attributes),
+       }, {
+               .class = PSC_TEMPERATURE,
+               .attr = temp_attributes,
+               .nattr = ARRAY_SIZE(temp_attributes),
+       }
+};
+
+/*
+ * Read the coefficients for direct mode.
+ */
+static int pmbus_read_coefficients(struct i2c_client *client,
+                                  struct pmbus_driver_info *info,
+                                  const struct pmbus_sensor_attr *attr)
+{
+       int rv;
+       union i2c_smbus_data data;
+       enum pmbus_sensor_classes class = attr->class;
+       s8 R;
+       s16 m, b;
+
+       data.block[0] = 2;
+       data.block[1] = attr->reg;
+       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[class] = m;
+       info->b[class] = b;
+       info->R[class] = R;
+
+       return rv;
+}
+
+static int pmbus_init_coefficients(struct i2c_client *client,
+                                  struct pmbus_driver_info *info)
+{
+       int i, n, ret = -EINVAL;
+       const struct pmbus_class_attr_map *map;
+       const struct pmbus_sensor_attr *attr;
+
+       for (i = 0; i < ARRAY_SIZE(class_attr_map); i++) {
+               map = &class_attr_map[i];
+               if (info->format[map->class] != direct)
+                       continue;
+               for (n = 0; n < map->nattr; n++) {
+                       attr = &map->attr[n];
+                       if (map->class != attr->class)
+                               continue;
+                       ret = pmbus_read_coefficients(client, info, attr);
+                       if (ret >= 0)
+                               break;
+               }
+               if (ret < 0) {
+                       dev_err(&client->dev,
+                               "No coefficients found for sensor class %d\n",
+                               map->class);
+                       return -EINVAL;
+               }
+       }
+
+       return 0;
+}
+
+/*
  * Identify chip parameters.
  * This function is called for all chips.
  */
@@ -2262,6 +2367,17 @@ static int pmbus_init_common(struct i2c_client *client, struct pmbus_data *data,
                        return ret;
                }
        }
+
+       if (data->flags & PMBUS_USE_COEFFICIENTS_CMD) {
+               if (!i2c_check_functionality(client->adapter,
+                                            I2C_FUNC_SMBUS_BLOCK_PROC_CALL))
+                       return -ENODEV;
+
+               ret = pmbus_init_coefficients(client, info);
+               if (ret < 0)
+                       return ret;
+       }
+
        return 0;
 }
 

diff --git a/include/linux/pmbus.h b/include/linux/pmbus.h
index 12c515a..fa9f081 100644 (file)
--- a/include/linux/pmbus.h
+++ b/include/linux/pmbus.h
@@ -65,6 +65,14 @@
  */
 #define PMBUS_NO_WRITE_PROTECT                 BIT(4)
 
+/*
+ * PMBUS_USE_COEFFICIENTS_CMD
+ *
+ * When this flag is set the PMBus core driver will use the COEFFICIENTS
+ * register to initialize the coefficients for the direct mode format.
+ */
+#define PMBUS_USE_COEFFICIENTS_CMD             BIT(5)
+
 struct pmbus_platform_data {
        u32 flags;              /* Device specific flags */