NCT5525D Super I/O

The Super I/O has the ID 0xd293 and the source can be found in src/superio/nuvoton/nct5525d/.

Logical devices

These logical devices are switched with device pnp <port>.<ldn> on|off below the chip superio/nuvoton/nct5525d entry:

Path	Function	on / off controls
2	UART A	CR30[0]
5	Keyboard controller	CR30[0]
b	Hardware monitor, SMBus master, LED	CR30[0]
16	Deep S5	LDN 16 CR30[0]

Logical devices that aren’t in the devicetree are left untouched. Several settings of this chip, like Deep S5 (2e.16), are battery-backed.

Pin configuration

The multi-function pins are only programmed when the chip ID matches:

Register	Description
pins_46_48	NCT5525D_PINS_46_48_GPIO to route pins 46/48 to GP63/GP64
tsi_pins	Route pins 39/40 to TSIC/TSID for AMD SB-TSI
gpio[0-5]	GP60-GP64 and GP66 as input or output, see the example

Only the GPIO6 pins are supported, so gpio[] has one entry per GPIO6 pin. A pin configured in gpio[] is switched from its default function to GPIO:

GPIO	Pin	Default function
GP60	33	PSON#
GP61	34	SLP_S3#
GP62	36	RSMRST#
GP63	46	SDA
GP64	48	SCL
GP66	56	THERMTRIP#

register "pins_46_48" = "NCT5525D_PINS_46_48_GPIO"
register "gpio[0]" = "{ .pin = NCT5525D_GP64, .mode = NCT5525D_GPIO_OUTPUT_HIGH,
			.push_pull = true }"

Hardware monitor

The hardware monitor is programmed when 2e.b is on and has its base in io 0x60. The temperature sensor types are set with systin_type, cputin_type and auxtin_type: NCT5525D_SENSOR_DIODE (thermal diode, voltage mode) or NCT5525D_SENSOR_DIODE_CURRENT (CPU thermal diode or diode-connected transistor such as a 2N3904, current mode).

SB-TSI agent 0 is enabled with tsi_agent0_enable, which needs tsi_pins and the SMBus master base in io 0x62. On eSPI, the SMBus master base needs an I/O decode range of 0x20 bytes.

SYSFAN and CPUFAN can run in SMART FAN IV mode, configured with a struct nct5525d_fan_config in the sysfan or cpufan register:

Field	Description
mode	Fan control mode, NCT5525D_FAN_SMART_FAN_IV
output	Fan output type, NCT5525D_FAN_OUT_PWM_OPEN_DRAIN
source	Temperature source, NCT5525D_TEMP_*
temp[4], curve_duty[4]	Curve, in degrees C and duty cycle 0-255
stop_duty_en, stop_duty	Lowest duty cycle
step_up_time, step_down_time	Step times in 0.1 s
crit_temp	Critical temperature, full speed above

For an SB-TSI source (NCT5525D_TEMP_SMBUSMASTER0), the fan control uses the raw SB-TSI value. When an AMD processor uses its extended temperature range (-49 to 206.875 degrees C), that value is the temperature plus 49 degrees C, so the driver adds 49 to the configured temperatures. The fan control temperature registers are signed, so thresholds are limited to 127 degrees C, which is 78 degrees C for an SB-TSI source in the extended range. Higher values are capped.

Example:

chip superio/nuvoton/nct5525d
	register "cputin_type" = "NCT5525D_SENSOR_DIODE_CURRENT"
	register "cpufan" = "{
		.mode = NCT5525D_FAN_SMART_FAN_IV,
		.source = NCT5525D_TEMP_CPUTIN,
		.temp = { 55, 60, 65, 70 },
		.curve_duty = { 0x4d, 0x80, 0xb3, 0xff },
		.stop_duty_en = true,
		.stop_duty = 0x4d,
		.crit_temp = 80,
	}"
	device pnp 2e.b on
		io 0x60 = 0x290
	end
end

For developers

The Super I/O generates ACPI using the SSDT generator for generic SuperIOs for the hardware monitor.