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Diffstat (limited to 'payloads/libpayload/arch/arm/cpu.S')
| -rw-r--r-- | payloads/libpayload/arch/arm/cpu.S | 117 |
1 files changed, 117 insertions, 0 deletions
diff --git a/payloads/libpayload/arch/arm/cpu.S b/payloads/libpayload/arch/arm/cpu.S new file mode 100644 index 000000000000..29a19e76df83 --- /dev/null +++ b/payloads/libpayload/arch/arm/cpu.S @@ -0,0 +1,117 @@ +/* + * Optimized assembly for low-level CPU operations on ARMv7 processors. + * + * Cache flushing code based off sys/arch/arm/arm/cpufunc_asm_armv7.S in NetBSD + * + * Copyright (c) 2010 Per Odlund <per.odlund@armagedon.se> + * Copyright (c) 2014 Google Inc. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * 3. The name of the author may not be used to endorse or promote products + * derived from this software without specific prior written permission. + * + * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND + * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE + * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE + * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE + * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL + * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS + * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) + * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT + * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY + * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF + * SUCH DAMAGE. + */ + +#include <arch/asm.h> + +/* + * Dcache invalidations by set/way work by passing a [way:sbz:set:sbz:level:0] + * bitfield in a register to the appropriate MCR instruction. This algorithm + * works by initializing a bitfield with the highest-numbered set and way, and + * generating a "set decrement" and a "way decrement". The former just contains + * the LSB of the set field, but the latter contains the LSB of the way field + * minus the highest valid set field... such that when you subtract it from a + * [way:0:level] field you end up with a [way - 1:highest_set:level] field + * through the magic of double subtraction. It's quite ingenius, really. + * Takes care to only use r0-r3 and ip so it's pefectly ABI-compatible without + * needing to write to memory. + */ + +.macro dcache_apply_all crm + dsb + mov r3, #-2 @ initialize level so that we start at 0 + +1: @next_level + add r3, r3, #2 @ increment level + + mrc p15, 1, r0, c0, c0, 1 @ read CLIDR + and ip, r0, #0x07000000 @ narrow to LoC + lsr ip, ip, #23 @ left align LoC (low 4 bits) + cmp r3, ip @ compare + bge 3f @done @ else fall through (r0 == CLIDR) + + add r2, r3, r3, lsr #1 @ r2 = (level << 1) * 3 / 2 + mov r1, r0, lsr r2 @ r1 = cache type + bfc r1, #3, #28 + cmp r1, #2 @ is it data or i&d? + blt 1b @next_level @ nope, skip level + + mcr p15, 2, r3, c0, c0, 0 @ select cache level + isb + mrc p15, 1, r0, c0, c0, 0 @ read CCSIDR + + ubfx ip, r0, #0, #3 @ get linesize from CCSIDR + add ip, ip, #4 @ apply bias + ubfx r2, r0, #13, #15 @ get numsets - 1 from CCSIDR + lsl r2, r2, ip @ shift to set position + orr r3, r3, r2 @ merge set into way/set/level + mov r1, #1 + lsl r1, r1, ip @ r1 = set decr + + ubfx ip, r0, #3, #10 @ get numways - 1 from [to be discarded] CCSIDR + clz r2, ip @ number of bits to MSB of way + lsl ip, ip, r2 @ shift by that into way position + mov r0, #1 + lsl r2, r0, r2 @ r2 now contains the way decr + mov r0, r3 @ get sets/level (no way yet) + orr r3, r3, ip @ merge way into way/set/level + bfc r0, #0, #4 @ clear low 4 bits (level) to get numset - 1 + sub r2, r2, r0 @ subtract from way decr + + /* r3 = ways/sets/level, r2 = way decr, r1 = set decr, r0 and ip are free */ +2: mcr p15, 0, r3, c7, \crm, 2 @ writeback and/or invalidate line + cmp r3, #15 @ are we done with this level (way/set == 0) + bls 1b @next_level @ yes, go to next level + lsr r0, r3, #4 @ clear level bits leaving only way/set bits + lsls r0, r0, #14 @ clear way bits leaving only set bits + subne r3, r3, r1 @ non-zero?, decrement set # + subeq r3, r3, r2 @ zero?, decrement way # and restore set count + b 2b + +3: @done + mov r0, #0 @ default back to cache level 0 + mcr p15, 2, r0, c0, c0, 0 @ select cache level + dsb + isb + bx lr +.endm + +ENTRY(dcache_invalidate_all) + dcache_apply_all crm=c6 +ENDPROC(dcache_invalidate_all) + +ENTRY(dcache_clean_all) + dcache_apply_all crm=c10 +ENDPROC(dcache_clean_all) + +ENTRY(dcache_clean_invalidate_all) + dcache_apply_all crm=c14 +ENDPROC(dcache_clean_invalidate_all) |