platform/mellanox: mlxreg-io: Add support for complex attributes

Add support for attributes composed from few registers.
Such attributes could occupy from 2 to 4 sequential registers.
For word size register space complex attributes can occupy up to two
registers, for byte size - up to four. These attributes can carry, for
example, CPLD or FPGA versioning, power consuming info, etcetera.
Such registers contain read-only data.
Signed-off-by: Vadim Pasternak <vadimp@mellanox.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>

drivers/platform/mellanox/mlxreg-io.c

@@ -30,6 +30,7 @@
  * @mlxreg_io_dev_attr: sysfs sensor device attribute array;
  * @group: sysfs attribute group;
  * @groups: list of sysfs attribute group for hwmon registration;
+ * @regsize: size of a register value;
  */
 struct mlxreg_io_priv_data {
 	struct platform_device *pdev;
@@ -39,27 +40,30 @@ struct mlxreg_io_priv_data {
 	struct sensor_device_attribute mlxreg_io_dev_attr[MLXREG_IO_ATT_NUM];
 	struct attribute_group group;
 	const struct attribute_group *groups[2];
+	int regsize;
 };
 
 static int
 mlxreg_io_get_reg(void *regmap, struct mlxreg_core_data *data, u32 in_val,
-		  bool rw_flag, u32 *regval)
+		  bool rw_flag, int regsize, u32 *regval)
 {
-	int ret;
+	int i, val, ret;
 
 	ret = regmap_read(regmap, data->reg, regval);
 	if (ret)
 		goto access_error;
 
 	/*
-	 * There are three kinds of attributes: single bit, full register's
-	 * bits and bit sequence. For the first kind field mask indicates which
-	 * bits are not related and field bit is set zero. For the second kind
-	 * field mask is set to zero and field bit is set with all bits one.
-	 * No special handling for such kind of attributes - pass value as is.
-	 * For the third kind, field mask indicates which bits are related and
-	 * field bit is set to the first bit number (from 1 to 32) is the bit
-	 * sequence.
+	 * There are four kinds of attributes: single bit, full register's
+	 * bits, bit sequence, bits in few registers For the first kind field
+	 * mask indicates which bits are not related and field bit is set zero.
+	 * For the second kind field mask is set to zero and field bit is set
+	 * with all bits one. No special handling for such kind of attributes -
+	 * pass value as is. For the third kind, the field mask indicates which
+	 * bits are related and the field bit is set to the first bit number
+	 * (from 1 to 32) is the bit sequence. For the fourth kind - the number
+	 * of registers which should be read for getting an attribute are
+	 * specified through 'data->regnum' field.
 	 */
 	if (!data->bit) {
 		/* Single bit. */
@@ -83,6 +87,19 @@ mlxreg_io_get_reg(void *regmap, struct mlxreg_core_data *data, u32 in_val,
 			/* Clear relevant bits and set them to new value. */
 			*regval = (*regval & ~data->mask) | in_val;
 		}
+	} else {
+		/*
+		 * Some attributes could occupied few registers in case regmap
+		 * bit size is 8 or 16. Compose such attributes from 'regnum'
+		 * registers. Such attributes contain read-only data.
+		 */
+		for (i = 1; i < data->regnum; i++) {
+			ret = regmap_read(regmap, data->reg + i, &val);
+			if (ret)
+				goto access_error;
+
+			*regval |= rol32(val, regsize * i);
+		}
 	}
 
 access_error:
@@ -99,7 +116,8 @@ mlxreg_io_attr_show(struct device *dev, struct device_attribute *attr,
 	u32 regval = 0;
 	int ret;
 
-	ret = mlxreg_io_get_reg(priv->pdata->regmap, data, 0, true, &regval);
+	ret = mlxreg_io_get_reg(priv->pdata->regmap, data, 0, true,
+				priv->regsize, &regval);
 	if (ret)
 		goto access_error;
 
@@ -128,7 +146,7 @@ mlxreg_io_attr_store(struct device *dev, struct device_attribute *attr,
 		return ret;
 
 	ret = mlxreg_io_get_reg(priv->pdata->regmap, data, input_val, false,
-				&regval);
+				priv->regsize, &regval);
 	if (ret)
 		goto access_error;
 
@@ -207,6 +225,9 @@ static int mlxreg_io_probe(struct platform_device *pdev)
 	}
 
 	priv->pdev = pdev;
+	priv->regsize = regmap_get_val_bytes(priv->pdata->regmap);
+	if (priv->regsize < 0)
+		return priv->regsize;
 
 	err = mlxreg_io_attr_init(priv);
 	if (err) {