Now that we have a thermal zone we can add active cooling
by specifying active cooling points (_ACx) which can
be tied to fan objects that turn fans on/off using GPIO
pins.
Cc: Leif Lindholm <l...@nuviainc.com>
Cc: Pete Batard <p...@akeo.ie>
Cc: Andrei Warkentin <awarken...@vmware.com>
Cc: Ard Biesheuvel <ard.biesheu...@arm.com>
Cc: Samer El-Haj-Mahmoud <samer.el-haj-mahm...@arm.com>
Signed-off-by: Jeremy Linton <jeremy.lin...@arm.com>
---
.../RaspberryPi/Drivers/ConfigDxe/SsdtThermal.asl | 83 ++++++++++++++++++++++
1 file changed, 83 insertions(+)
create mode 100644 Platform/RaspberryPi/Drivers/ConfigDxe/SsdtThermal.asl
diff --git a/Platform/RaspberryPi/Drivers/ConfigDxe/SsdtThermal.asl
b/Platform/RaspberryPi/Drivers/ConfigDxe/SsdtThermal.asl
new file mode 100644
index 0000000000..c87bda6dbc
--- /dev/null
+++ b/Platform/RaspberryPi/Drivers/ConfigDxe/SsdtThermal.asl
@@ -0,0 +1,83 @@
+/** @file
+ *
+ * Secondary System Description Table (SSDT) for active (fan) cooling
+ *
+ * Copyright (c) 2020, Arm Ltd. All rights reserved.
+ *
+ * SPDX-License-Identifier: BSD-2-Clause-Patent
+ *
+ **/
+
+#include <IndustryStandard/Bcm2711.h>
+#include <IndustryStandard/Bcm2836.h>
+#include <IndustryStandard/Bcm2836Gpio.h>
+
+#include <IndustryStandard/Acpi.h>
+
+DefinitionBlock(__FILE__, "SSDT", 5, "RPIFDN", "RPITHFAN", 2)
+{
+#if (GPIO_FAN_PIN != 0)
+ External(\_SB_.EC0, DeviceObj)
+ External(\_SB_.EC0.TZ0, DeviceObj)
+
+ Scope (\_SB_.EC0)
+ {
+ // Describe a fan
+ PowerResource(PFAN, 0, 0) {
+ OperationRegion (GPIO, SystemMemory, GPIO_BASE_ADDRESS, 0x1000)
+ Field (GPIO, DWordAcc, NoLock, Preserve) {
+ Offset(0x1C),
+ GPS0, 32,
+ GPS1, 32,
+ RES1, 32,
+ GPC0, 32,
+ GPC1, 32,
+ RES2, 32,
+ GPL1, 32,
+ GPL2, 32
+ }
+ // We are hitting a GPIO pin to on/off the fan
+ // this assumes that UEFI has programmed the
+ // direction as OUT.
+ // (search "rpi gpio fan controller" for how to
+ // wire this up if your not electrically inclined
+ // the basic idea is to use a BJT/etc to switch a
+ // larger voltage through a fan where the GPIO pin
+ // feeds a NPN/PNP base. Thats because its unlikly
+ // that the fan can be driven directly from the GPIO
+ // pin due to hitting the current limit on the pins.
+ // Matching a resistor between the GPIO->Base can
+ // allow pretty much any random NPN with a reasonable
+ // EC current to work (to limit the GPIO current).)
+ Method (_STA) {
+ if ( GPL1 & (1 << GPIO_FAN_PIN) ) {
+ Return ( 1 ) // present and enabled
+ }
+ Return ( 0 )
+ }
+ Method (_ON) { //turn fan on
+ Store((1 << GPIO_FAN_PIN), GPS0)
+ }
+ Method (_OFF) { //turn fan off
+ Store((1 << GPIO_FAN_PIN), GPC0)
+ }
+ }
+ Device(FAN) {
+ // Note, not currently an ACPIv4 fan
+ // the latter adds speed control/detection
+ // but in the case of linux needs FIF, FPS, FSL, and FST
+ Name(_HID, EISAID("PNP0C0B"))
+ Name(_PR0, Package() {PFAN})
+ }
+ }
+
+ // merge in an active cooling point.
+ Scope (\_SB_.EC0.TZ0)
+ {
+ Method(_AC0) { return(3332) } // (60K) active cooling trip point,
+ // if this is lower than PSV then we
+ // prefer active cooling
+ Name(_AL0, Package(){\_SB_.EC0.FAN}) // the fan used for AC0 above
+ }
+#endif
+}
--
2.13.7
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