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/*
* Copyright (C) 2016 Bernhard Nortmann <bernhard.nortmann@web.de>
*
* Permission is hereby granted, free of charge, to any person obtaining a
* copy of this software and associated documentation files (the "Software"),
* to deal in the Software without restriction, including without limitation
* the rights to use, copy, modify, merge, publish, distribute, sublicense,
* and/or sell copies of the Software, and to permit persons to whom the
* Software is furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice (including the next
* paragraph) shall be included in all copies or substantial portions of the
* Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
* DEALINGS IN THE SOFTWARE.
*/
/*
* ARM thunk code to read the SID root key using register-based access.
*
* This is necessary for certain SoCs (e.g. H3), as the values read via
* memory mapping might not be consistent. For background information see
* https://groups.google.com/forum/#!topic/linux-sunxi/ynyIP8c61Qs
*/
SID_BASE .req r0
sid_key_index .req r1
.set SID_PRCTL, 0x40 /* SID program/read control register */
.set SID_PRKEY, 0x50 /* SID program key value register */
.set SID_RDKEY, 0x60 /* SID read key value register */
.set SID_OP_LOCK, 0xAC /* Efuse operation lock value */
.set SID_READ_START, (1 << 1) /* bit 1 of SID_PRCTL, Software Read Start */
.set SID_PG_START, (1 << 0) /* bit 0 of SID_PRCTL, Software Program Start */
sid_read_root_key:
ldr SID_BASE, sid_base
ldr sid_key_index, offset
adr r3, sid_result /* result pointer */
sid_read_loop:
mov r2, sid_key_index, lsl #16 /* PG_INDEX value */
orr r2, #SID_OP_LOCK << 8 /* OP_LOCK to enable SID_READ_START */
orr r2, #SID_READ_START
str r2, [SID_BASE, #SID_PRCTL] /* write SID_PRCTL */
sid_read_wait:
ldr r2, [SID_BASE, #SID_PRCTL] /* read SID_PRCTL */
tst r2, #SID_READ_START /* check if read operation completed */
bne sid_read_wait /* loop while bit 1 still set */
ldr r2, [SID_BASE, #SID_RDKEY] /* read SID key value */
str r2, [r3], #4 /* store SID value */
add sid_key_index, #4
ldr r2, end
cmp sid_key_index, r2
blo sid_read_loop /* loop while (sid_key_index < 0x10) */
mov r2, #0
str r2, [SID_BASE, #SID_PRCTL] /* clear SID_PRCTL */
bx lr
sid_base: .word 0
offset: .word 0
end: .word 0
sid_result: /* receives the values read from the SID registers */
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