riscv: implement cache-management errata for T-Head SoCs
From: Heiko Stuebner <heiko@...> Date: Thu, 27 Jan 2022 20:50:05 +0100
Commit-Message
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. Reviewed-by: Samuel Holland <samuel@...> Tested-by: Samuel Holland <samuel@...> Reviewed-by: Guo Ren <guoren@...> Signed-off-by: Heiko Stuebner <heiko@...>
Patch-Comment
arch/riscv/Kconfig.erratas | 11 +++++++ arch/riscv/errata/thead/errata.c | 20 ++++++++++++ arch/riscv/include/asm/errata_list.h | 48 +++++++++++++++++++++++++--- 3 files changed, 74 insertions(+), 5 deletions(-)
Statistics
- 74 lines added
- 5 lines removed
Changes
-------------------------- arch/riscv/Kconfig.erratas --------------------------
index 457ac72c9b36..3223e533fd87 100644
@@ -55,4 +55,15 @@ 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
+ select RISCV_DMA_NONCOHERENT
+ 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
----------------------- arch/riscv/errata/thead/errata.c -----------------------
index b37b6fedd53b..202c83f677b2 100644
@@ -27,6 +27,23 @@ static bool errata_probe_pbmt(unsigned int stage,
return false;
}
+static bool errata_probe_cmo(unsigned int stage,
+ unsigned long arch_id, unsigned long impid)
+{
+#ifdef CONFIG_ERRATA_THEAD_CMO
+ if (arch_id != 0 || impid != 0)
+ return false;
+
+ if (stage == RISCV_ALTERNATIVES_EARLY_BOOT)
+ return false;
+
+ riscv_noncoherent_supported();
+ return true;
+#else
+ return false;
+#endif
+}
+
static u32 thead_errata_probe(unsigned int stage,
unsigned long archid, unsigned long impid)
{
@@ -35,6 +52,9 @@ static u32 thead_errata_probe(unsigned int stage,
if (errata_probe_pbmt(stage, archid, impid))
cpu_req_errata |= (1U << ERRATA_THEAD_PBMT);
+ if (errata_probe_cmo(stage, archid, impid))
+ cpu_req_errata |= (1U << ERRATA_THEAD_CMO);
+
return cpu_req_errata;
}
--------------------- arch/riscv/include/asm/errata_list.h ---------------------
index 79d89aeeaa6c..19a771085781 100644
@@ -16,7 +16,8 @@
#ifdef CONFIG_ERRATA_THEAD
#define ERRATA_THEAD_PBMT 0
+#define ERRATA_THEAD_CMO 1
+#define ERRATA_THEAD_NUMBER 2
#endif
#define CPUFEATURE_SVPBMT 0
@@ -88,17 +89,54 @@ asm volatile(ALTERNATIVE( \
#define ALT_THEAD_PMA(_val)
#endif
+/*
+ * 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_2( \
+ __nops(6), \
"mv a0, %1\n\t" \
"j 2f\n\t" \
"3:\n\t" \
"cbo." __stringify(_op) " (a0)\n\t" \
"add a0, a0, %0\n\t" \
"2:\n\t" \
+ "bltu a0, %2, 3b\n\t" \
+ "nop", 0, CPUFEATURE_ZICBOM, 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"((unsigned long)(_start) & ~((_cachesize) - 1UL)), \
"r"((unsigned long)(_start) + (_size)) \