[PATCH v2 3/3] riscv: implement cache-management errata for T-Head SoCs

Heiko Stuebner
2022-05-11T21:41:57Z

The T-Head C906 and C910 implement a scheme for handling
cache operations different from the generic Zicbom extension.

Add an errata for it next to the generic dma coherency ops.

Tested-by: Samuel Holland <samuel@sholland.org>
Signed-off-by: Heiko Stuebner <heiko@sntech.de>
---
arch/riscv/Kconfig.erratas | 10 ++++++
arch/riscv/errata/thead/errata.c | 5 +++
arch/riscv/include/asm/errata_list.h | 47 +++++++++++++++++++++++++---
3 files changed, 58 insertions(+), 4 deletions(-)

diff --git a/arch/riscv/Kconfig.erratas b/arch/riscv/Kconfig.erratas
index ebfcd5cc6eaf..213629bac5d7 100644
--- a/arch/riscv/Kconfig.erratas
+++ b/arch/riscv/Kconfig.erratas
@@ -54,4 +54,14 @@ config ERRATA_THEAD_PBMT

If you don't know what to do here, say "Y".

+config ERRATA_THEAD_CMO
+ bool "Apply T-Head cache management errata"
+ depends on ERRATA_THEAD && RISCV_ISA_ZICBOM
+ default y
+ help
+ This will apply the cache management errata to handle the
+ non-standard handling on non-coherent operations on T-Head SoCs.
+
+ If you don't know what to do here, say "Y".
+
endmenu
diff --git a/arch/riscv/errata/thead/errata.c b/arch/riscv/errata/thead/errata.c
index e5d75270b99c..9545f43d3504 100644
--- a/arch/riscv/errata/thead/errata.c
+++ b/arch/riscv/errata/thead/errata.c
@@ -33,6 +33,11 @@ static const struct errata_info errata_list[ERRATA_THEAD_NUMBER] = {
.stage = RISCV_ALTERNATIVES_EARLY_BOOT,
.check_func = errata_mt_check_func
},
+ {
+ .name = "cache-management",
+ .stage = RISCV_ALTERNATIVES_BOOT,
+ .check_func = errata_mt_check_func
+ },
};

static u32 thead_errata_probe(unsigned int stage, unsigned long archid, unsigned long impid)
diff --git a/arch/riscv/include/asm/errata_list.h b/arch/riscv/include/asm/errata_list.h
index eebcd4415049..1da311fc5126 100644
--- a/arch/riscv/include/asm/errata_list.h
+++ b/arch/riscv/include/asm/errata_list.h
@@ -16,7 +16,8 @@

#ifdef CONFIG_ERRATA_THEAD
#define ERRATA_THEAD_PBMT 0
-#define ERRATA_THEAD_NUMBER 1
+#define ERRATA_THEAD_CMO 1
+#define ERRATA_THEAD_NUMBER 2
#endif

#define CPUFEATURE_SVPBMT 0
@@ -111,8 +112,37 @@ asm volatile(ALTERNATIVE( \
#define CBO_CLEAN_A0 ".long 0x25200F"
#define CBO_FLUSH_A0 ".long 0x05200F"

+/*
+ * dcache.ipa rs1 (invalidate, physical address)
+ * | 31 - 25 | 24 - 20 | 19 - 15 | 14 - 12 | 11 - 7 | 6 - 0 |
+ * 0000001 01010 rs1 000 00000 0001011
+ * dache.iva rs1 (invalida, virtual address)
+ * 0000001 00110 rs1 000 00000 0001011
+ *
+ * dcache.cpa rs1 (clean, physical address)
+ * | 31 - 25 | 24 - 20 | 19 - 15 | 14 - 12 | 11 - 7 | 6 - 0 |
+ * 0000001 01001 rs1 000 00000 0001011
+ * dcache.cva rs1 (clean, virtual address)
+ * 0000001 00100 rs1 000 00000 0001011
+ *
+ * dcache.cipa rs1 (clean then invalidate, physical address)
+ * | 31 - 25 | 24 - 20 | 19 - 15 | 14 - 12 | 11 - 7 | 6 - 0 |
+ * 0000001 01011 rs1 000 00000 0001011
+ * dcache.civa rs1 (... virtual address)
+ * 0000001 00111 rs1 000 00000 0001011
+ *
+ * sync.s (make sure all cache operations finished)
+ * | 31 - 25 | 24 - 20 | 19 - 15 | 14 - 12 | 11 - 7 | 6 - 0 |
+ * 0000000 11001 00000 000 00000 0001011
+ */
+#define THEAD_INVAL_A0 ".long 0x0265000b"
+#define THEAD_CLEAN_A0 ".long 0x0245000b"
+#define THEAD_FLUSH_A0 ".long 0x0275000b"
+#define THEAD_SYNC_S ".long 0x0190000b"
+
#define ALT_CMO_OP(_op, _start, _size, _cachesize) \
-asm volatile(ALTERNATIVE( \
+asm volatile(ALTERNATIVE_2( \
+ "nop\n\t" \
"nop\n\t" \
"nop\n\t" \
"nop\n\t" \
@@ -124,8 +154,17 @@ asm volatile(ALTERNATIVE( \
CBO_##_op##_A0 "\n\t" \
"add a0, a0, %0\n\t" \
"2:\n\t" \
- "bltu a0, %2, 3b\n\t", 0, \
- CPUFEATURE_CMO, CONFIG_RISCV_ISA_ZICBOM) \
+ "bltu a0, %2, 3b\n\t" \
+ "nop", 0, CPUFEATURE_CMO, CONFIG_RISCV_ISA_ZICBOM, \
+ "mv a0, %1\n\t" \
+ "j 2f\n\t" \
+ "3:\n\t" \
+ THEAD_##_op##_A0 "\n\t" \
+ "add a0, a0, %0\n\t" \
+ "2:\n\t" \
+ "bltu a0, %2, 3b\n\t" \
+ THEAD_SYNC_S, THEAD_VENDOR_ID, \
+ ERRATA_THEAD_CMO, CONFIG_ERRATA_THEAD_CMO) \
: : "r"(_cachesize), \
"r"(ALIGN((_start), (_cachesize))), \
"r"(ALIGN((_start) + (_size), (_cachesize))))
--
2.35.1