iBoot/platform/t7000/asm.S

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ArmAsm
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2023-07-08 13:03:17 -07:00
/*
* Copyright (c) 2013-2014 Apple Inc. All rights reserved.
*
* This document is the property of Apple Inc.
* It is considered confidential and proprietary.
*
* This document may not be reproduced or transmitted in any form,
* in whole or in part, without the express written permission of
* Apple Inc.
*/
.text
.align 2
.globl _platform_start
_platform_start:
////////////////////////////////////////////////
// Must preserve X0 and X1
////////////////////////////////////////////////
// Enable the L2 cache load/store prefetcher.
mrs x2, s3_0_c15_c5_0 // HID5
and x2, x2, #~(3<<44) // Enable L2C load (bit 44)/store (bit 45) prefetch
msr s3_0_c15_c5_0, x2 // HID5
isb
ret
.align 2
.globl _platform_halt
_platform_halt:
// For Typhoon, we must disable the MTLB prefetcher before doing WFI.
// <rdar://problem/15837639> iBoot: implement Cyclone/Typhoon WFI workaround
mrs x1, s3_0_c15_c2_0 // Read HID2
orr x0, x1, #(1 << 13) // Set HID2.DisableMTLBPrefetch
msr s3_0_c15_c2_0, x0 // Write HID2
dsb sy
isb sy
wfi
// Re-enable MTLB prefetcher after WFI falls through.
msr s3_0_c15_c2_0, x1 // Restore HID2
dsb sy
isb sy
ret