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MIPS: Join the coherent domain when a CM is present

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MIPS Linux expects the bootloader to leave the boot CPU a member of the
coherent domain when running on a system with a CM, and we will need to
do so if we wish to make use of IOCUs to have cache-coherent DMA in
U-Boot (and on some systems there is no choice in that matter). When a
CM is present, join the coherent domain after completing cache
initialisation.

Signed-off-by: Paul Burton <paul.burton@imgtec.com>
This commit is contained in:
Paul Burton 2016-09-21 11:18:55 +01:00 • committed by Daniel Schwierzeck
parent 4baa0ab67d
commit 7953354b07
2 changed files with 43 additions and 0 deletions
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5
arch/mips/include/asm/cm.h
View file

@ -19,6 +19,7 @@
#define GCR_L2_TAG_STATE_UPPER 0x060c
#define GCR_L2_DATA 0x0610
#define GCR_L2_DATA_UPPER 0x0614
#define GCR_Cx_COHERENCE 0x2008
/* GCR_REV CM versions */
#define GCR_REV_CM3 0x0800
@ -32,6 +33,10 @@
#define GCR_L2_CONFIG_SETSZ_BITS 4
#define GCR_L2_CONFIG_BYPASS (1 << 20)
/* GCR_Cx_COHERENCE */
#define GCR_Cx_COHERENCE_DOM_EN (0xff << 0)
#define GCR_Cx_COHERENCE_EN (0x1 << 0)
#ifndef __ASSEMBLY__
#include <asm/io.h>

38
arch/mips/lib/cache_init.S
View file

@ -378,6 +378,44 @@ l2_unbypass:
ehb
2:
# ifdef CONFIG_MIPS_CM
/* Config3 must exist for a CM to be present */
mfc0 t0, CP0_CONFIG, 1
bgez t0, 2f
mfc0 t0, CP0_CONFIG, 2
bgez t0, 2f
/* Check Config3.CMGCR to determine CM presence */
mfc0 t0, CP0_CONFIG, 3
and t0, t0, MIPS_CONF3_CMGCR
beqz t0, 2f
/* Change Config.K0 to a coherent CCA */
mfc0 t0, CP0_CONFIG
li t1, CONF_CM_CACHABLE_COW
#if __mips_isa_rev >= 2
ins t0, t1, 0, 3
#else
ori t0, t0, CONF_CM_CMASK
xori t0, t0, CONF_CM_CMASK
or t0, t0, t1
#endif
mtc0 t0, CP0_CONFIG
/*
* Join the coherent domain such that the caches of this core are kept
* coherent with those of other cores.
*/
PTR_LI t0, CKSEG1ADDR(CONFIG_MIPS_CM_BASE)
lw t1, GCR_REV(t0)
li t2, GCR_REV_CM3
li t3, GCR_Cx_COHERENCE_EN
bge t1, t2, 1f
li t3, GCR_Cx_COHERENCE_DOM_EN
1: sw t3, GCR_Cx_COHERENCE(t0)
ehb
2:
# endif
#endif
return: