[PATCH 1/8] powerpc/8xx: Remove CPU6 ERRATA Workaround

From: Christophe Leroy
Date: Fri Jan 12 2018 - 07:45:49 EST

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CPU6 ERRATA affects only MPC860 revisions prior to C.0. Manufacturing
of those revisiosn was stopped in 1999-2000.
Therefore, it has been almost 20 years since this ERRATA has been
fixed in the silicon.

This patch removes the workaround for that ERRATA.

Signed-off-by: Christophe Leroy <christophe.leroy@xxxxxx>
---
arch/powerpc/configs/mpc866_ads_defconfig | 1 -
arch/powerpc/include/asm/reg_8xx.h | 82 -------------------------------
arch/powerpc/kernel/head_8xx.S | 54 +++++---------------
arch/powerpc/platforms/8xx/Kconfig | 12 -----
4 files changed, 12 insertions(+), 137 deletions(-)

diff --git a/arch/powerpc/configs/mpc866_ads_defconfig b/arch/powerpc/configs/mpc866_ads_defconfig
index f1f176c29fa3..5320735395e7 100644
--- a/arch/powerpc/configs/mpc866_ads_defconfig
+++ b/arch/powerpc/configs/mpc866_ads_defconfig
@@ -13,7 +13,6 @@ CONFIG_EXPERT=y
CONFIG_PARTITION_ADVANCED=y
CONFIG_MPC86XADS=y
CONFIG_8xx_COPYBACK=y
-CONFIG_8xx_CPU6=y
CONFIG_GEN_RTC=y
CONFIG_HZ_1000=y
CONFIG_MATH_EMULATION=y
diff --git a/arch/powerpc/include/asm/reg_8xx.h b/arch/powerpc/include/asm/reg_8xx.h
index 53a7e2955d3e..7192eece6c3e 100644
--- a/arch/powerpc/include/asm/reg_8xx.h
+++ b/arch/powerpc/include/asm/reg_8xx.h
@@ -66,86 +66,4 @@
#define DC_DFWT 0x40000000 /* Data cache is forced write through */
#define DC_LES 0x20000000 /* Caches are little endian mode */

-#ifdef CONFIG_8xx_CPU6
-#define do_mtspr_cpu6(rn, rn_addr, v) \
- do { \
- int _reg_cpu6 = rn_addr, _tmp_cpu6; \
- asm volatile("stw %0, %1;" \
- "lwz %0, %1;" \
- "mtspr " __stringify(rn) ",%2" : \
- : "r" (_reg_cpu6), "m"(_tmp_cpu6), \
- "r" ((unsigned long)(v)) \
- : "memory"); \
- } while (0)
-
-#define do_mtspr(rn, v) asm volatile("mtspr " __stringify(rn) ",%0" : \
- : "r" ((unsigned long)(v)) \
- : "memory")
-#define mtspr(rn, v) \
- do { \
- if (rn == SPRN_IMMR) \
- do_mtspr_cpu6(rn, 0x3d30, v); \
- else if (rn == SPRN_IC_CST) \
- do_mtspr_cpu6(rn, 0x2110, v); \
- else if (rn == SPRN_IC_ADR) \
- do_mtspr_cpu6(rn, 0x2310, v); \
- else if (rn == SPRN_IC_DAT) \
- do_mtspr_cpu6(rn, 0x2510, v); \
- else if (rn == SPRN_DC_CST) \
- do_mtspr_cpu6(rn, 0x3110, v); \
- else if (rn == SPRN_DC_ADR) \
- do_mtspr_cpu6(rn, 0x3310, v); \
- else if (rn == SPRN_DC_DAT) \
- do_mtspr_cpu6(rn, 0x3510, v); \
- else if (rn == SPRN_MI_CTR) \
- do_mtspr_cpu6(rn, 0x2180, v); \
- else if (rn == SPRN_MI_AP) \
- do_mtspr_cpu6(rn, 0x2580, v); \
- else if (rn == SPRN_MI_EPN) \
- do_mtspr_cpu6(rn, 0x2780, v); \
- else if (rn == SPRN_MI_TWC) \
- do_mtspr_cpu6(rn, 0x2b80, v); \
- else if (rn == SPRN_MI_RPN) \
- do_mtspr_cpu6(rn, 0x2d80, v); \
- else if (rn == SPRN_MI_CAM) \
- do_mtspr_cpu6(rn, 0x2190, v); \
- else if (rn == SPRN_MI_RAM0) \
- do_mtspr_cpu6(rn, 0x2390, v); \
- else if (rn == SPRN_MI_RAM1) \
- do_mtspr_cpu6(rn, 0x2590, v); \
- else if (rn == SPRN_MD_CTR) \
- do_mtspr_cpu6(rn, 0x3180, v); \
- else if (rn == SPRN_M_CASID) \
- do_mtspr_cpu6(rn, 0x3380, v); \
- else if (rn == SPRN_MD_AP) \
- do_mtspr_cpu6(rn, 0x3580, v); \
- else if (rn == SPRN_MD_EPN) \
- do_mtspr_cpu6(rn, 0x3780, v); \
- else if (rn == SPRN_M_TWB) \
- do_mtspr_cpu6(rn, 0x3980, v); \
- else if (rn == SPRN_MD_TWC) \
- do_mtspr_cpu6(rn, 0x3b80, v); \
- else if (rn == SPRN_MD_RPN) \
- do_mtspr_cpu6(rn, 0x3d80, v); \
- else if (rn == SPRN_M_TW) \
- do_mtspr_cpu6(rn, 0x3f80, v); \
- else if (rn == SPRN_MD_CAM) \
- do_mtspr_cpu6(rn, 0x3190, v); \
- else if (rn == SPRN_MD_RAM0) \
- do_mtspr_cpu6(rn, 0x3390, v); \
- else if (rn == SPRN_MD_RAM1) \
- do_mtspr_cpu6(rn, 0x3590, v); \
- else if (rn == SPRN_DEC) \
- do_mtspr_cpu6(rn, 0x2c00, v); \
- else if (rn == SPRN_TBWL) \
- do_mtspr_cpu6(rn, 0x3880, v); \
- else if (rn == SPRN_TBWU) \
- do_mtspr_cpu6(rn, 0x3a80, v); \
- else if (rn == SPRN_DPDR) \
- do_mtspr_cpu6(rn, 0x2d30, v); \
- else \
- do_mtspr(rn, v); \
- } while (0)
-#endif
-
#endif /* _ASM_POWERPC_REG_8xx_H */
diff --git a/arch/powerpc/kernel/head_8xx.S b/arch/powerpc/kernel/head_8xx.S
index 4fee00d414e8..728b513c07b8 100644
--- a/arch/powerpc/kernel/head_8xx.S
+++ b/arch/powerpc/kernel/head_8xx.S
@@ -33,23 +33,6 @@
#include <asm/fixmap.h>
#include <asm/export.h>

-/* Macro to make the code more readable. */
-#ifdef CONFIG_8xx_CPU6
-#define SPRN_MI_TWC_ADDR 0x2b80
-#define SPRN_MI_RPN_ADDR 0x2d80
-#define SPRN_MD_TWC_ADDR 0x3b80
-#define SPRN_MD_RPN_ADDR 0x3d80
-
-#define MTSPR_CPU6(spr, reg, treg) \
- li treg, spr##_ADDR; \
- stw treg, 12(r0); \
- lwz treg, 12(r0); \
- mtspr spr, reg
-#else
-#define MTSPR_CPU6(spr, reg, treg) \
- mtspr spr, reg
-#endif
-
#if CONFIG_TASK_SIZE <= 0x80000000 && CONFIG_PAGE_OFFSET >= 0x80000000
/* By simply checking Address >= 0x80000000, we know if its a kernel address */
#define SIMPLE_KERNEL_ADDRESS 1
@@ -326,7 +309,7 @@ SystemCall:
#endif

InstructionTLBMiss:
-#if defined(CONFIG_8xx_CPU6) || defined(ITLB_MISS_KERNEL) || defined(CONFIG_HUGETLB_PAGE)
+#if defined(ITLB_MISS_KERNEL) || defined(CONFIG_HUGETLB_PAGE)
mtspr SPRN_SPRG_SCRATCH2, r3
#endif
EXCEPTION_PROLOG_0
@@ -393,7 +376,7 @@ _ENTRY(ITLBMiss_cmp)
/* Insert the APG into the TWC from the Linux PTE. */
rlwimi r11, r10, 0, 25, 26
/* Load the MI_TWC with the attributes for this "segment." */
- MTSPR_CPU6(SPRN_MI_TWC, r11, r3) /* Set segment attributes */
+ mtspr SPRN_MI_TWC, r11 /* Set segment attributes */

#if defined (CONFIG_HUGETLB_PAGE) && defined (CONFIG_PPC_4K_PAGES)
rlwimi r10, r11, 1, MI_SPS16K
@@ -415,10 +398,10 @@ _ENTRY(ITLBMiss_cmp)
#else
rlwimi r10, r11, 0, 0x0ff8 /* Set 24-27, clear 20-23,28 */
#endif
- MTSPR_CPU6(SPRN_MI_RPN, r10, r3) /* Update TLB entry */
+ mtspr SPRN_MI_RPN, r10 /* Update TLB entry */

/* Restore registers */
-#if defined(CONFIG_8xx_CPU6) || defined(ITLB_MISS_KERNEL) || defined(CONFIG_HUGETLB_PAGE)
+#if defined(ITLB_MISS_KERNEL) || defined(CONFIG_HUGETLB_PAGE)
mfspr r3, SPRN_SPRG_SCRATCH2
#endif
EXCEPTION_EPILOG_0
@@ -512,7 +495,7 @@ _ENTRY(DTLBMiss_jmp)
* It is bit 25 in the Linux PTE and bit 30 in the TWC
*/
rlwimi r11, r10, 32-5, 30, 30
- MTSPR_CPU6(SPRN_MD_TWC, r11, r3)
+ mtspr SPRN_MD_TWC, r11

/* In 4k pages mode, SPS (bit 28) in RPN must match PS[1] (bit 29)
* In 16k pages mode, SPS is always 1 */
@@ -546,7 +529,7 @@ _ENTRY(DTLBMiss_jmp)
rlwimi r10, r11, 0, 24, 28 /* Set 24-27, clear 28 */
#endif
rlwimi r10, r11, 0, 20, 20 /* clear 20 */
- MTSPR_CPU6(SPRN_MD_RPN, r10, r3) /* Update TLB entry */
+ mtspr SPRN_MD_RPN, r10 /* Update TLB entry */

/* Restore registers */
mfspr r3, SPRN_SPRG_SCRATCH2
@@ -684,12 +667,12 @@ DTLBMissIMMR:
mtcr r3
/* Set 512k byte guarded page and mark it valid */
li r10, MD_PS512K | MD_GUARDED | MD_SVALID
- MTSPR_CPU6(SPRN_MD_TWC, r10, r11)
+ mtspr SPRN_MD_TWC, r10
mfspr r10, SPRN_IMMR /* Get current IMMR */
rlwinm r10, r10, 0, 0xfff80000 /* Get 512 kbytes boundary */
ori r10, r10, 0xf0 | MD_SPS16K | _PAGE_SHARED | _PAGE_DIRTY | \
_PAGE_PRESENT | _PAGE_NO_CACHE
- MTSPR_CPU6(SPRN_MD_RPN, r10, r11) /* Update TLB entry */
+ mtspr SPRN_MD_RPN, r10 /* Update TLB entry */

li r11, RPN_PATTERN
mtspr SPRN_DAR, r11 /* Tag DAR */
@@ -701,11 +684,11 @@ DTLBMissLinear:
mtcr r3
/* Set 8M byte page and mark it valid */
li r11, MD_PS8MEG | MD_SVALID
- MTSPR_CPU6(SPRN_MD_TWC, r11, r3)
+ mtspr SPRN_MD_TWC, r11
rlwinm r10, r10, 0, 0x0f800000 /* 8xx supports max 256Mb RAM */
ori r10, r10, 0xf0 | MD_SPS16K | _PAGE_SHARED | _PAGE_DIRTY | \
_PAGE_PRESENT
- MTSPR_CPU6(SPRN_MD_RPN, r10, r11) /* Update TLB entry */
+ mtspr SPRN_MD_RPN, r10 /* Update TLB entry */

li r11, RPN_PATTERN
mtspr SPRN_DAR, r11 /* Tag DAR */
@@ -718,11 +701,11 @@ ITLBMissLinear:
mtcr r3
/* Set 8M byte page and mark it valid */
li r11, MI_PS8MEG | MI_SVALID | _PAGE_EXEC
- MTSPR_CPU6(SPRN_MI_TWC, r11, r3)
+ mtspr SPRN_MI_TWC, r11
rlwinm r10, r10, 0, 0x0f800000 /* 8xx supports max 256Mb RAM */
ori r10, r10, 0xf0 | MI_SPS16K | _PAGE_SHARED | _PAGE_DIRTY | \
_PAGE_PRESENT
- MTSPR_CPU6(SPRN_MI_RPN, r10, r11) /* Update TLB entry */
+ mtspr SPRN_MI_RPN, r10 /* Update TLB entry */

mfspr r3, SPRN_SPRG_SCRATCH2
EXCEPTION_EPILOG_0
@@ -933,13 +916,6 @@ start_here:
*/
lis r6, swapper_pg_dir@ha
tophys(r6,r6)
-#ifdef CONFIG_8xx_CPU6
- lis r4, cpu6_errata_word@h
- ori r4, r4, cpu6_errata_word@l
- li r3, 0x3f80
- stw r3, 12(r4)
- lwz r3, 12(r4)
-#endif
mtspr SPRN_M_TW, r6
lis r4,2f@h
ori r4,r4,2f@l
@@ -1094,12 +1070,6 @@ swapper_pg_dir:
abatron_pteptrs:
.space 8

-#ifdef CONFIG_8xx_CPU6
- .globl cpu6_errata_word
-cpu6_errata_word:
- .space 16
-#endif
-
#ifdef CONFIG_PPC_8xx_PERF_EVENT
.globl itlb_miss_counter
itlb_miss_counter:
diff --git a/arch/powerpc/platforms/8xx/Kconfig b/arch/powerpc/platforms/8xx/Kconfig
index e7f33e96b395..e417988eaef9 100644
--- a/arch/powerpc/platforms/8xx/Kconfig
+++ b/arch/powerpc/platforms/8xx/Kconfig
@@ -124,18 +124,6 @@ config 8xx_GPIO

If in doubt, say Y here.

-config 8xx_CPU6
- bool "CPU6 Silicon Errata (860 Pre Rev. C)"
- help
- MPC860 CPUs, prior to Rev C have some bugs in the silicon, which
- require workarounds for Linux (and most other OSes to work). If you
- get a BUG() very early in boot, this might fix the problem. For
- more details read the document entitled "MPC860 Family Device Errata
- Reference" on Freescale's website. This option also incurs a
- performance hit.
-
- If in doubt, say N here.
-
config 8xx_CPU15
bool "CPU15 Silicon Errata"
depends on !HUGETLB_PAGE
--
2.13.3

Next message: Christophe Leroy: "[PATCH 2/8] powerpc/8xx: remove EXCEPTION_PROLOG/EPILOG_0 and change r3 to r12"
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