[PATCH v8] platform: generic: renesas: rzfive: Add SBI EXT to check for enabling IOCP errata

[Lad Prabhakar]

I/O Coherence Port (IOCP) provides an AXI interface for connecting
external non-caching masters, such as DMA controllers. The accesses
from IOCP are coherent with D-Caches and L2 Cache.

IOCP is a specification option and is disabled on the Renesas RZ/Five
SoC due to this reason IP blocks using DMA will fail.

As a workaround for SoCs with IOCP disabled CMO needs to be handled by
software. Firstly OpenSBI configures the memory region as
"Memory, Non-cacheable, Bufferable" and passes this region as a global
shared dma pool as a DT node. With DMA_GLOBAL_POOL enabled all DMA
allocations happen from this region and synchronization callbacks are
implemented to synchronize when doing DMA transactions.

SBI_EXT_ANDES_IOCP_SW_WORKAROUND checks if the IOCP errata should be
applied to handle cache management.

Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj at bp.renesas.com>
Reviewed-by: Yu Chien Peter Lin <peterlin at andestech.com>
Reviewed-by: Conor Dooley <conor.dooley at microchip.com>
---
v7->v8
* Fixed typo controlable -> controllable
* Included RB tag from Lin-san and Conor

v6->v7
* Added a new section for conf and control registers
* Made use of misa_extension('U')
* For unsupported funcid's now returning SBI_EINVAL
* Renamed ANDES_SBI_EXT_IOCP_SW_WORKAROUND -> SBI_EXT_ANDES_IOCP_SW_WORKAROUND

v5->v6
* Moved ANDES_SBI_EXT_IOCP_SW_WORKAROUND to andes_sbi.h
* Moved helpers to check IOCP to common header so that we re-use code

v5:
https://patchwork.ozlabs.org/project/opensbi/patch/20230213215111.32017-4-prabhakar.mahadev-lad.rj@bp.renesas.com/
---
 platform/generic/include/andes/andes45.h   | 23 ++++++++++++++--
 platform/generic/include/andes/andes_sbi.h | 32 ++++++++++++++++++++++
 platform/generic/renesas/rzfive/rzfive.c   | 21 ++++++++++++++
 3 files changed, 74 insertions(+), 2 deletions(-)
 create mode 100644 platform/generic/include/andes/andes_sbi.h

diff --git a/platform/generic/include/andes/andes45.h b/platform/generic/include/andes/andes45.h
index 08b3d18..f570994 100644
--- a/platform/generic/include/andes/andes45.h
+++ b/platform/generic/include/andes/andes45.h
@@ -4,7 +4,26 @@
 #define CSR_MARCHID_MICROID 0xfff
 
 /* Memory and Miscellaneous Registers */
-#define CSR_MCACHE_CTL 0x7ca
-#define CSR_MCCTLCOMMAND 0x7cc
+#define CSR_MCACHE_CTL		0x7ca
+#define CSR_MCCTLCOMMAND	0x7cc
+
+/* Configuration Control & Status Registers */
+#define CSR_MICM_CFG		0xfc0
+#define CSR_MDCM_CFG		0xfc1
+#define CSR_MMSC_CFG		0xfc2
+
+#define MICM_CFG_ISZ_OFFSET		6
+#define MICM_CFG_ISZ_MASK		(0x7  << MICM_CFG_ISZ_OFFSET)
+
+#define MDCM_CFG_DSZ_OFFSET		6
+#define MDCM_CFG_DSZ_MASK		(0x7  << MDCM_CFG_DSZ_OFFSET)
+
+#define MMSC_CFG_CCTLCSR_OFFSET		16
+#define MMSC_CFG_CCTLCSR_MASK		(0x1 << MMSC_CFG_CCTLCSR_OFFSET)
+#define MMSC_IOCP_OFFSET			47
+#define MMSC_IOCP_MASK			(0x1ULL << MMSC_IOCP_OFFSET)
+
+#define MCACHE_CTL_CCTL_SUEN_OFFSET	8
+#define MCACHE_CTL_CCTL_SUEN_MASK	(0x1 << MCACHE_CTL_CCTL_SUEN_OFFSET)
 
 #endif /* _RISCV_ANDES45_H */
diff --git a/platform/generic/include/andes/andes_sbi.h b/platform/generic/include/andes/andes_sbi.h
new file mode 100644
index 0000000..12b83c2
--- /dev/null
+++ b/platform/generic/include/andes/andes_sbi.h
@@ -0,0 +1,32 @@
+#ifndef _RISCV_ANDES_SBI_H
+#define _RISCV_ANDES_SBI_H
+
+#include <sbi/riscv_asm.h>
+
+#include "andes45.h"
+
+enum sbi_ext_andes_fid {
+	SBI_EXT_ANDES_FID0 = 0, /* Reserved for future use */
+	SBI_EXT_ANDES_IOCP_SW_WORKAROUND,
+};
+
+static bool andes45_cache_controllable(void)
+{
+	return (((csr_read(CSR_MICM_CFG) & MICM_CFG_ISZ_MASK) ||
+		 (csr_read(CSR_MDCM_CFG) & MDCM_CFG_DSZ_MASK)) &&
+		(csr_read(CSR_MMSC_CFG) & MMSC_CFG_CCTLCSR_MASK) &&
+		(csr_read(CSR_MCACHE_CTL) & MCACHE_CTL_CCTL_SUEN_MASK) &&
+		misa_extension('U'));
+}
+
+static bool andes45_iocp_disabled(void)
+{
+	return (csr_read(CSR_MMSC_CFG) & MMSC_IOCP_MASK) ? false : true;
+}
+
+static bool andes45_apply_iocp_sw_workaround(void)
+{
+	return andes45_cache_controllable() & andes45_iocp_disabled();
+}
+
+#endif /* _RISCV_ANDES_SBI_H */
diff --git a/platform/generic/renesas/rzfive/rzfive.c b/platform/generic/renesas/rzfive/rzfive.c
index 4d71d0d..b6df1a7 100644
--- a/platform/generic/renesas/rzfive/rzfive.c
+++ b/platform/generic/renesas/rzfive/rzfive.c
@@ -5,8 +5,10 @@
  */
 
 #include <andes/andes45_pma.h>
+#include <andes/andes_sbi.h>
 #include <platform_override.h>
 #include <sbi/sbi_domain.h>
+#include <sbi/sbi_error.h>
 #include <sbi_utils/fdt/fdt_helper.h>
 
 static const struct andes45_pma_region renesas_rzfive_pma_regions[] = {
@@ -28,6 +30,24 @@ static int renesas_rzfive_final_init(bool cold_boot, const struct fdt_match *mat
 					 array_size(renesas_rzfive_pma_regions));
 }
 
+static int renesas_rzfive_vendor_ext_provider(long funcid,
+					      const struct sbi_trap_regs *regs,
+					      unsigned long *out_value,
+					      struct sbi_trap_info *out_trap,
+					      const struct fdt_match *match)
+{
+	switch (funcid) {
+	case SBI_EXT_ANDES_IOCP_SW_WORKAROUND:
+		*out_value = andes45_apply_iocp_sw_workaround();
+		break;
+
+	default:
+		return SBI_EINVAL;
+	}
+
+	return 0;
+}
+
 int renesas_rzfive_early_init(bool cold_boot, const struct fdt_match *match)
 {
 	/*
@@ -55,4 +75,5 @@ const struct platform_override renesas_rzfive = {
 	.match_table = renesas_rzfive_match,
 	.early_init = renesas_rzfive_early_init,
 	.final_init = renesas_rzfive_final_init,
+	.vendor_ext_provider = renesas_rzfive_vendor_ext_provider,
 };
-- 
2.17.1