[PATCH v12 2/6] riscv: errata: Add Andes alternative ports

From: Prabhakar
Date: Fri Aug 18 2023 - 09:58:48 EST

From: Lad Prabhakar <prabhakar.mahadev-lad.rj@xxxxxxxxxxxxxx>

Add required ports of the Alternative scheme for Andes CPU cores.

I/O Coherence Port (IOCP) provides an AXI interface for connecting external
non-caching masters, such as DMA controllers. IOCP is a specification
option and is disabled on the Renesas RZ/Five SoC due to this reason cache
management needs a software workaround.

Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@xxxxxxxxxxxxxx>
Reviewed-by: Conor Dooley <conor.dooley@xxxxxxxxxxxxx>
Tested-by: Conor Dooley <conor.dooley@xxxxxxxxxxxxx> # tyre-kicking on a d1
---
v11 -> v12
* No change

v10 -> v11
* No change

v9 -> v10
* Included TB tag from Conor

v8 -> v9
* Rebased to code on Palmer's for/next
* Dropped calling patch_text_nosync() as dont use
patch_text_nosync() call

v7 -> v8
* Now patching the code using patch_text_nosync() and riscv_alternative_fix_offsets()

v6 -> v7
* Renamed RZFIVE_SBI_EXT_IOCP_SW_WORKAROUND -> ANDES_SBI_EXT_IOCP_SW_WORKAROUND
* Dropped "depends on !XIP_KERNEL" for ERRATA_ANDES config

v5 -> v6
* Dropped patching alternative and now just probing IOCP

v4 -> v5
* Sorted the Kconfig/Makefile/Switch based on Core name
* Added a comments
* Introduced RZFIVE_SBI_EXT_IOCP_SW_WORKAROUND SBI EXT ID to check if
CMO needs to be applied. Is there a way we can access the DTB while patching
as we can drop this SBI EXT ID and add a DT property instead for cmo?

RFC v3 -> v4
* New patch
---
arch/riscv/Kconfig.errata | 21 +++++++++
arch/riscv/errata/Makefile | 1 +
arch/riscv/errata/andes/Makefile | 1 +
arch/riscv/errata/andes/errata.c | 66 ++++++++++++++++++++++++++++
arch/riscv/include/asm/alternative.h | 3 ++
arch/riscv/include/asm/errata_list.h | 5 +++
arch/riscv/kernel/alternative.c | 5 +++
7 files changed, 102 insertions(+)
create mode 100644 arch/riscv/errata/andes/Makefile
create mode 100644 arch/riscv/errata/andes/errata.c

diff --git a/arch/riscv/Kconfig.errata b/arch/riscv/Kconfig.errata
index 0c8f4652cd82..92c779764b27 100644
--- a/arch/riscv/Kconfig.errata
+++ b/arch/riscv/Kconfig.errata
@@ -1,5 +1,26 @@
menu "CPU errata selection"

+config ERRATA_ANDES
+ bool "Andes AX45MP errata"
+ depends on RISCV_ALTERNATIVE
+ help
+ All Andes errata Kconfig depend on this Kconfig. Disabling
+ this Kconfig will disable all Andes errata. Please say "Y"
+ here if your platform uses Andes CPU cores.
+
+ Otherwise, please say "N" here to avoid unnecessary overhead.
+
+config ERRATA_ANDES_CMO
+ bool "Apply Andes cache management errata"
+ depends on ERRATA_ANDES && MMU && ARCH_R9A07G043
+ 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 Andes cores.
+
+ If you don't know what to do here, say "Y".
+
config ERRATA_SIFIVE
bool "SiFive errata"
depends on RISCV_ALTERNATIVE
diff --git a/arch/riscv/errata/Makefile b/arch/riscv/errata/Makefile
index 7b2637c8c332..8a2739485123 100644
--- a/arch/riscv/errata/Makefile
+++ b/arch/riscv/errata/Makefile
@@ -2,5 +2,6 @@ ifdef CONFIG_RELOCATABLE
KBUILD_CFLAGS += -fno-pie
endif

+obj-$(CONFIG_ERRATA_ANDES) += andes/
obj-$(CONFIG_ERRATA_SIFIVE) += sifive/
obj-$(CONFIG_ERRATA_THEAD) += thead/
diff --git a/arch/riscv/errata/andes/Makefile b/arch/riscv/errata/andes/Makefile
new file mode 100644
index 000000000000..2d644e19caef
--- /dev/null
+++ b/arch/riscv/errata/andes/Makefile
@@ -0,0 +1 @@
+obj-y += errata.o
diff --git a/arch/riscv/errata/andes/errata.c b/arch/riscv/errata/andes/errata.c
new file mode 100644
index 000000000000..197db68cc8da
--- /dev/null
+++ b/arch/riscv/errata/andes/errata.c
@@ -0,0 +1,66 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Erratas to be applied for Andes CPU cores
+ *
+ * Copyright (C) 2023 Renesas Electronics Corporation.
+ *
+ * Author: Lad Prabhakar <prabhakar.mahadev-lad.rj@xxxxxxxxxxxxxx>
+ */
+
+#include <linux/memory.h>
+#include <linux/module.h>
+
+#include <asm/alternative.h>
+#include <asm/cacheflush.h>
+#include <asm/errata_list.h>
+#include <asm/patch.h>
+#include <asm/processor.h>
+#include <asm/sbi.h>
+#include <asm/vendorid_list.h>
+
+#define ANDESTECH_AX45MP_MARCHID 0x8000000000008a45UL
+#define ANDESTECH_AX45MP_MIMPID 0x500UL
+#define ANDESTECH_SBI_EXT_ANDES 0x0900031E
+
+#define ANDES_SBI_EXT_IOCP_SW_WORKAROUND 1
+
+static long ax45mp_iocp_sw_workaround(void)
+{
+ struct sbiret ret;
+
+ /*
+ * ANDES_SBI_EXT_IOCP_SW_WORKAROUND SBI EXT checks if the IOCP is missing and
+ * cache is controllable only then CMO will be applied to the platform.
+ */
+ ret = sbi_ecall(ANDESTECH_SBI_EXT_ANDES, ANDES_SBI_EXT_IOCP_SW_WORKAROUND,
+ 0, 0, 0, 0, 0, 0);
+
+ return ret.error ? 0 : ret.value;
+}
+
+static bool errata_probe_iocp(unsigned int stage, unsigned long arch_id, unsigned long impid)
+{
+ if (!IS_ENABLED(CONFIG_ERRATA_ANDES_CMO))
+ return false;
+
+ if (arch_id != ANDESTECH_AX45MP_MARCHID || impid != ANDESTECH_AX45MP_MIMPID)
+ return false;
+
+ if (!ax45mp_iocp_sw_workaround())
+ return false;
+
+ /* Set this just to make core cbo code happy */
+ riscv_cbom_block_size = 1;
+ riscv_noncoherent_supported();
+
+ return true;
+}
+
+void __init_or_module andes_errata_patch_func(struct alt_entry *begin, struct alt_entry *end,
+ unsigned long archid, unsigned long impid,
+ unsigned int stage)
+{
+ errata_probe_iocp(stage, archid, impid);
+
+ /* we have nothing to patch here ATM so just return back */
+}
diff --git a/arch/riscv/include/asm/alternative.h b/arch/riscv/include/asm/alternative.h
index 6a41537826a7..f6cfca939c92 100644
--- a/arch/riscv/include/asm/alternative.h
+++ b/arch/riscv/include/asm/alternative.h
@@ -46,6 +46,9 @@ struct alt_entry {
u32 patch_id; /* The patch ID (erratum ID or cpufeature ID) */
};

+void andes_errata_patch_func(struct alt_entry *begin, struct alt_entry *end,
+ unsigned long archid, unsigned long impid,
+ unsigned int stage);
void sifive_errata_patch_func(struct alt_entry *begin, struct alt_entry *end,
unsigned long archid, unsigned long impid,
unsigned int stage);
diff --git a/arch/riscv/include/asm/errata_list.h b/arch/riscv/include/asm/errata_list.h
index fb1a810f3d8c..e2ecd01bfac7 100644
--- a/arch/riscv/include/asm/errata_list.h
+++ b/arch/riscv/include/asm/errata_list.h
@@ -11,6 +11,11 @@
#include <asm/hwcap.h>
#include <asm/vendorid_list.h>

+#ifdef CONFIG_ERRATA_ANDES
+#define ERRATA_ANDESTECH_NO_IOCP 0
+#define ERRATA_ANDESTECH_NUMBER 1
+#endif
+
#ifdef CONFIG_ERRATA_SIFIVE
#define ERRATA_SIFIVE_CIP_453 0
#define ERRATA_SIFIVE_CIP_1200 1
diff --git a/arch/riscv/kernel/alternative.c b/arch/riscv/kernel/alternative.c
index 6b75788c18e6..b0345992a35e 100644
--- a/arch/riscv/kernel/alternative.c
+++ b/arch/riscv/kernel/alternative.c
@@ -45,6 +45,11 @@ static void riscv_fill_cpu_mfr_info(struct cpu_manufacturer_info_t *cpu_mfr_info

cpu_mfr_info->feature_probe_func = NULL;
switch (cpu_mfr_info->vendor_id) {
+#ifdef CONFIG_ERRATA_ANDES
+ case ANDESTECH_VENDOR_ID:
+ cpu_mfr_info->patch_func = andes_errata_patch_func;
+ break;
+#endif
#ifdef CONFIG_ERRATA_SIFIVE
case SIFIVE_VENDOR_ID:
cpu_mfr_info->patch_func = sifive_errata_patch_func;
--
2.34.1