[RFC PATCH v2 3/3] 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.

RENESAS_RZFIVE_SBI_EXT_IOCP_SW_WORKAROUND SBI EXT 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>
---
Hi Lin-san,

If Andes plan to use similar approach I can move this code into some common
file so that it can be shared. Please share your thoughts.

Cheers, Prabhakar
---
 platform/generic/renesas/rzfive/rzfive.c | 63 ++++++++++++++++++++++++
 1 file changed, 63 insertions(+)

diff --git a/platform/generic/renesas/rzfive/rzfive.c b/platform/generic/renesas/rzfive/rzfive.c
index 54a4c29..2cb9b3b 100644
--- a/platform/generic/renesas/rzfive/rzfive.c
+++ b/platform/generic/renesas/rzfive/rzfive.c
@@ -9,6 +9,33 @@
 #include <sbi/sbi_domain.h>
 #include <sbi_utils/fdt/fdt_helper.h>
 
+#define RENESAS_RZFIVE_SBI_EXT_IOCP_SW_WORKAROUND	0
+
+/* AX45MP registers */
+#define AX45MP_CSR_MISA_CFG			0x301
+#define AX45MP_CSR_MICM_CFG			0xfc0
+#define AX45MP_CSR_MDCM_CFG			0xfc1
+#define AX45MP_CSR_MMSC_CFG			0xfc2
+#define AX45MP_CSR_MCACHE_CTL			0x7ca
+
+/* AX45MP register bit offsets and masks */
+#define AX45MP_MISA_20_OFFSET			20
+#define AX45MP_MISA_20_MASK			(0x1 << AX45MP_MISA_20_OFFSET)
+
+#define AX45MP_MICM_CFG_ISZ_OFFSET		6
+#define AX45MP_MICM_CFG_ISZ_MASK		(0x7  << AX45MP_MICM_CFG_ISZ_OFFSET)
+
+#define AX45MP_MDCM_CFG_DSZ_OFFSET		6
+#define AX45MP_MDCM_CFG_DSZ_MASK		(0x7  << AX45MP_MDCM_CFG_DSZ_OFFSET)
+
+#define AX45MP_MMSC_CFG_CCTLCSR_OFFSET		16
+#define AX45MP_MMSC_CFG_CCTLCSR_MASK		(0x1 << AX45MP_MMSC_CFG_CCTLCSR_OFFSET)
+#define AX45MP_MMSC_IOCP_OFFSET			47
+#define AX45MP_MMSC_IOCP_MASK			(0x1ULL << AX45MP_MMSC_IOCP_OFFSET)
+
+#define AX45MP_MCACHE_CTL_CCTL_SUEN_OFFSET	8
+#define AX45MP_MCACHE_CTL_CCTL_SUEN_MASK	(0x1 << AX45MP_MCACHE_CTL_CCTL_SUEN_OFFSET)
+
 static const struct andes45_pma_region renesas_rzfive_pma_regions[] = {
 	{
 		.pa = 0x58000000,
@@ -28,6 +55,41 @@ static int renesas_rzfive_final_init(bool cold_boot, const struct fdt_match *mat
 					 array_size(renesas_rzfive_pma_regions));
 }
 
+static bool renesas_rzfive_cpu_cache_controlable(void)
+{
+	return (((csr_read(AX45MP_CSR_MICM_CFG) & AX45MP_MICM_CFG_ISZ_MASK) ||
+		 (csr_read(AX45MP_CSR_MDCM_CFG) & AX45MP_MDCM_CFG_DSZ_MASK)) &&
+		(csr_read(AX45MP_CSR_MISA_CFG) & AX45MP_MISA_20_MASK) &&
+		(csr_read(AX45MP_CSR_MMSC_CFG) & AX45MP_MMSC_CFG_CCTLCSR_MASK) &&
+		(csr_read(AX45MP_CSR_MCACHE_CTL) & AX45MP_MCACHE_CTL_CCTL_SUEN_MASK));
+}
+
+static bool renesas_rzfive_cpu_iocp_disabled(void)
+{
+	return (csr_read(AX45MP_CSR_MMSC_CFG) & AX45MP_MMSC_IOCP_MASK) ? false : true;
+}
+
+static bool renesas_rzfive_apply_iocp_sw_workaround(void)
+{
+	return renesas_rzfive_cpu_cache_controlable() & renesas_rzfive_cpu_iocp_disabled();
+}
+static int renesas_rzfive_vendor_ext_provider(long extid, 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 RENESAS_RZFIVE_SBI_EXT_IOCP_SW_WORKAROUND:
+		*out_value = renesas_rzfive_apply_iocp_sw_workaround();
+		break;
+
+	default:
+		break;
+	}
+
+	return 0;
+}
 int renesas_rzfive_early_init(bool cold_boot, const struct fdt_match *match)
 {
 	/*
@@ -53,4 +115,5 @@ 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