platform/x86: mlx-platform: Add support for fan direction register

Provide support for the fan direction register.
This register shows configuration for system fans direction, which could
be forward or reversed.
For forward direction - relevant bit is set 0;
For reversed direction - relevant bit is set 1.
Signed-off-by: Vadim Pasternak <vadimp@mellanox.com>
Signed-off-by: Darren Hart (VMware) <dvhart@infradead.org>

drivers/platform/x86/mlx-platform.c

@@ -33,6 +33,7 @@
 #define MLXPLAT_CPLD_LPC_REG_LED3_OFFSET	0x22
 #define MLXPLAT_CPLD_LPC_REG_LED4_OFFSET	0x23
 #define MLXPLAT_CPLD_LPC_REG_LED5_OFFSET	0x24
+#define MLXPLAT_CPLD_LPC_REG_FAN_DIRECTION	0x2a
 #define MLXPLAT_CPLD_LPC_REG_GP1_OFFSET		0x30
 #define MLXPLAT_CPLD_LPC_REG_WP1_OFFSET		0x31
 #define MLXPLAT_CPLD_LPC_REG_GP2_OFFSET		0x32
@@ -1184,6 +1185,12 @@ static struct mlxreg_core_data mlxplat_mlxcpld_default_ng_regs_io_data[] = {
 		.bit = 1,
 		.mode = 0444,
 	},
+	{
+		.label = "fan_dir",
+		.reg = MLXPLAT_CPLD_LPC_REG_FAN_DIRECTION,
+		.bit = GENMASK(7, 0),
+		.mode = 0200,
+	},
 };
 
 static struct mlxreg_core_platform_data mlxplat_default_ng_regs_io_data = {
@@ -1307,6 +1314,7 @@ static bool mlxplat_mlxcpld_readable_reg(struct device *dev, unsigned int reg)
 	case MLXPLAT_CPLD_LPC_REG_LED3_OFFSET:
 	case MLXPLAT_CPLD_LPC_REG_LED4_OFFSET:
 	case MLXPLAT_CPLD_LPC_REG_LED5_OFFSET:
+	case MLXPLAT_CPLD_LPC_REG_FAN_DIRECTION:
 	case MLXPLAT_CPLD_LPC_REG_GP1_OFFSET:
 	case MLXPLAT_CPLD_LPC_REG_WP1_OFFSET:
 	case MLXPLAT_CPLD_LPC_REG_GP2_OFFSET:
@@ -1360,6 +1368,7 @@ static bool mlxplat_mlxcpld_volatile_reg(struct device *dev, unsigned int reg)
 	case MLXPLAT_CPLD_LPC_REG_LED3_OFFSET:
 	case MLXPLAT_CPLD_LPC_REG_LED4_OFFSET:
 	case MLXPLAT_CPLD_LPC_REG_LED5_OFFSET:
+	case MLXPLAT_CPLD_LPC_REG_FAN_DIRECTION:
 	case MLXPLAT_CPLD_LPC_REG_GP1_OFFSET:
 	case MLXPLAT_CPLD_LPC_REG_GP2_OFFSET:
 	case MLXPLAT_CPLD_LPC_REG_AGGR_OFFSET: