/** @file
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*
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* Secondary System Description Table (SSDT) for active (fan) cooling
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*
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* Copyright (c) 2020, Arm Ltd. All rights reserved.
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*
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* SPDX-License-Identifier: BSD-2-Clause-Patent
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*
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**/
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#include <IndustryStandard/Bcm2711.h>
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#include <IndustryStandard/Bcm2836.h>
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#include <IndustryStandard/Bcm2836Gpio.h>
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#include <IndustryStandard/Acpi.h>
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DefinitionBlock (__FILE__, "SSDT", 2, "RPIFDN", "RPITHFAN", 2)
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{
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External (\_SB_.EC00, DeviceObj)
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External (\_SB_.EC00.TZ00, DeviceObj)
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Scope (\_SB_.EC00)
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{
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// Define a NameOp we will modify during InstallTable
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Name (GIOP, 0x2) //08 47 49 4f 50 0a 02 (value must be >1)
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Name (FTMP, 0x2)
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// Describe a fan
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PowerResource (PFAN, 0, 0) {
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OperationRegion (GPIO, SystemMemory, GPIO_BASE_ADDRESS, 0x1000)
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Field (GPIO, DWordAcc, NoLock, Preserve) {
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Offset (0x1C),
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GPS0, 32,
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GPS1, 32,
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RES1, 32,
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GPC0, 32,
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GPC1, 32,
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RES2, 32,
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GPL1, 32,
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GPL2, 32
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}
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// We are hitting a GPIO pin to on/off a fan.
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// This assumes that UEFI has programmed the
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// direction as OUT. Given the current limitations
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// on the GPIO pins, its recommended to use
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// the GPIO to switch a larger voltage/current
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// for the fan rather than driving it directly.
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Method (_STA) {
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if (GPL1 & (1 << GIOP)) {
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Return (1) // present and enabled
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}
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Return (0)
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}
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Method (_ON) { // turn fan on
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Store (1 << GIOP, GPS0)
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}
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Method (_OFF) { // turn fan off
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Store (1 << GIOP, GPC0)
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}
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}
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Device (FAN0) {
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// Note, not currently an ACPIv4 fan
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// the latter adds speed control/detection
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// but in the case of linux needs FIF, FPS, FSL, and FST
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Name (_HID, EISAID ("PNP0C0B"))
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Name (_PR0, Package () { PFAN })
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}
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}
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// merge in an active cooling point.
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Scope (\_SB_.EC00.TZ00)
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{
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Method (_AC0) { Return ( (FTMP * 10) + 2732) } // (60C) active cooling trip point,
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// if this is lower than PSV then we
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// prefer active cooling
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Name (_AL0, Package () { \_SB_.EC00.FAN0 }) // the fan used for AC0 above
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}
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}
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