[edk2-devel] [PATCH 1/3] Platform/RaspberryPi4: Add a basic thermal zone

[Jeremy Linton]

Rather than exporting the temp sensor or mailbox
in ACPI land we can wrap them in AML and use the default
ACPI drivers provided by the OS. This enables the use of
"sensors" in linux to report the SOC temp.

This commit also adds a basic passive cooling ACPI thermalzone
with trip points for passive cooling (throttling) handled
by the vc firmware, hibernate and critical shutdown. The
vc apparently kicks in at ~80C, so the hibernate and critical
set points are set at +5 and +10 of that. In the future
CPPC should be able to monitor the thermal throttling.

Cc: Leif Lindholm <leif at nuviainc.com>
Cc: Pete Batard <pete at akeo.ie>
Cc: Andrei Warkentin <awarkentin at vmware.com>
Cc: Ard Biesheuvel <ard.biesheuvel at arm.com>
Cc: Samer El-Haj-Mahmoud <Samer.El-Haj-Mahmoud at arm.com>
Signed-off-by: Jeremy Linton <jeremy.linton at arm.com>
---
 Platform/RaspberryPi/AcpiTables/Dsdt.asl | 31 +++++++++++++++++++++++++++++++
 1 file changed, 31 insertions(+)

diff --git a/Platform/RaspberryPi/AcpiTables/Dsdt.asl b/Platform/RaspberryPi/AcpiTables/Dsdt.asl
index 353af2d876..a5c9567cdf 100644
--- a/Platform/RaspberryPi/AcpiTables/Dsdt.asl
+++ b/Platform/RaspberryPi/AcpiTables/Dsdt.asl
@@ -252,6 +252,37 @@ DefinitionBlock ("Dsdt.aml", "DSDT", 5, "RPIFDN", "RPI", 2)
         }
       })
     }
+
+    // Define a simple thermal zone. The idea here is we compute the SOC temp
+    // via a register we can read, and give it to the OS. This enables basic
+    // reports from the "sensors" utility, and the OS can then poll and take
+    // actions if that temp exceeds any of the given thresholds.
+    Device(EC0)
+    {
+      Name(_HID, EISAID("PNP0C06"))
+      Name (_CCA, 0x0)
+
+      // all temps in are tenths of K (aka 2732 is the min temps in linux (aka 0C))
+      ThermalZone(TZ0) {
+        Method(_TMP, 0, Serialized) {
+          OperationRegion (TEMS, SystemMemory, 0xfd5d2200, 0x8)
+          Field (TEMS, DWordAcc, NoLock, Preserve) {
+            TMPS, 32
+          }
+          return (((419949 - ((TMPS & 0x3ff) * 487)) / 100) + 2732);
+        }
+        Method(_SCP, 3) { }              // receive cooling policy from OS
+
+        Method(_CRT) { return(3632) }    // (90K) Critical temp point (immediate power-off)
+        Method(_HOT) { return(3582) }    // (85K) HOT state where OS should hibernate
+        Method(_PSV) { return(3532) }    // (80K) Passive cooling (CPU throttling) trip point
+
+        // SSDT inserts _AC0/_AL0 @60C here, if a FAN is configured
+
+        Name(_TZP, 10)                   //The OSPM must poll this device every 1 seconds
+        Name(_PSL, Package(){ \_SB_.CPU0, \_SB_.CPU1, \_SB_.CPU2, \_SB_.CPU3})
+      }
+    }
 #endif
 
   }
-- 
2.13.7


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