c908x: Add fastmem setting support

Xuantie C908X supports fast memory configuration vector and scalar
memory access instructions to access external SRAM.
Configure the starting address and size through CSR_MFASTMBA. For
specific settings, please refer to the datasheet.
Dynamic configuration is achieved by parsing dts through opensbi.
The dts reference configuration is as follows:
```
/ {
	compatible = "xuantie,c908x";
	model = "xuantie,c908x";

	fastmem {
		mfastmba = <0x12 0x34567890>;
	};
};
```

Signed-off-by: hanyu.cp <[email protected]>

docs/platform/thead-c9xx.md

@@ -25,3 +25,17 @@ Here is the simplest boot flow for a fpga prototype:
 
 For more details, refer:
  [zero stage boot](https://github.com/c-sky/zero_stage_boot)
+
+DTS Example: (fastmem)
+-----------------------------
+
+```
+/ {
+	compatible = "xuantie,c908x";
+	model = "xuantie,c908x";
+
+	fastmem {
+		mfastmba = <0x12 0x34567890>;
+	};
+};
+```

platform/generic/Kconfig

@@ -62,6 +62,7 @@ config PLATFORM_STARFIVE_JH7110
 config PLATFORM_THEAD
 	bool "THEAD C9xx support"
 	select THEAD_C9XX_ERRATA
+	select THEAD_C9XX_EXTFUNC
 	select THEAD_C9XX_PMU
 	default n
 

platform/generic/include/thead/c9xx_encoding.h

@@ -20,6 +20,8 @@
 #define THEAD_C9XX_CSR_MEXSTATUS	0x7e1
 #define THEAD_C9XX_CSR_MNMICAUSE	0x7e2
 #define THEAD_C9XX_CSR_MNMIPC		0x7e3
+#define THEAD_C9XX_CSR_MFASTMBA		0x7eb
+#define THEAD_C9XX_CSR_MFASTMBAH	0x7ec
 #define THEAD_C9XX_CSR_MHPMCR		0x7f0
 #define THEAD_C9XX_CSR_MHPMSR		0x7f1
 #define THEAD_C9XX_CSR_MHPMER		0x7f2
@@ -95,6 +97,7 @@
 
 /* T-HEAD C9xx U mode CSR.  */
 #define THEAD_C9XX_CSR_FXCR		0x800
+#define THEAD_C9XX_CSR_UTNMODE		0x8da
 
 /* T-HEAD C9xx MMU extentions.  */
 #define THEAD_C9XX_CSR_SMIR		0x9c0

platform/generic/include/thead/c9xx_extfunc.h

@@ -0,0 +1,10 @@
+
+#ifndef __RISCV_THEAD_C9XX_EXTFUNC_H____
+#define __RISCV_THEAD_C9XX_EXTFUNC_H____
+
+/* Fast Memory Setting */
+#define THEAD_QUIRK_EXTFUNC_FASTMEM		BIT(0)
+
+void thead_c9xx_fastmem_init(void);
+
+#endif // __RISCV_THEAD_C9XX_EXTFUNC_H____

platform/generic/thead/Kconfig

@@ -7,3 +7,7 @@ config THEAD_C9XX_PMU
 config THEAD_C9XX_ERRATA
 	bool "T-HEAD c9xx errata support"
 	default n
+
+config THEAD_C9XX_EXTFUNC
+	bool "THEAD c9xx extfunc support"
+	default n

platform/generic/thead/objects.mk

@@ -9,6 +9,7 @@ platform-objs-$(CONFIG_THEAD_C9XX_PMU) += thead/thead_c9xx_pmu.o
 
 platform-objs-$(CONFIG_THEAD_C9XX_ERRATA) += thead/thead_c9xx_tlb_trap_handler.o
 platform-objs-$(CONFIG_THEAD_C9XX_ERRATA) += thead/thead_c9xx_errata_tlb_flush.o
+platform-objs-$(CONFIG_THEAD_C9XX_EXTFUNC) += thead/thead_c9xx_extfunc_fastmem.o
 
 carray-platform_override_modules-$(CONFIG_PLATFORM_THEAD) += thead_generic
 platform-objs-$(CONFIG_PLATFORM_THEAD) += thead/thead-generic.o

platform/generic/thead/thead-generic.c

@@ -8,6 +8,7 @@
 
 #include <platform_override.h>
 #include <thead/c9xx_errata.h>
+#include <thead/c9xx_extfunc.h>
 #include <thead/c9xx_pmu.h>
 #include <sbi/sbi_const.h>
 #include <sbi/sbi_platform.h>
@@ -16,6 +17,7 @@
 #include <sbi_utils/fdt/fdt_helper.h>
 
 struct thead_generic_quirks {
+	u64	extfunc;
 	u64	errata;
 };
 
@@ -27,6 +29,9 @@ static int thead_generic_early_init(bool cold_boot,
 	if (quirks->errata & THEAD_QUIRK_ERRATA_TLB_FLUSH)
 		thead_register_tlb_flush_trap_handler();
 
+	if (quirks->extfunc & THEAD_QUIRK_EXTFUNC_FASTMEM)
+		thead_c9xx_fastmem_init();
+
 	return 0;
 }
 
@@ -45,8 +50,13 @@ static struct thead_generic_quirks thead_th1520_quirks = {
 	.errata = THEAD_QUIRK_ERRATA_TLB_FLUSH | THEAD_QUIRK_ERRATA_THEAD_PMU,
 };
 
+static struct thead_generic_quirks xuantie_c908x_quirks = {
+	.extfunc = THEAD_QUIRK_EXTFUNC_FASTMEM,
+};
+
 static const struct fdt_match thead_generic_match[] = {
 	{ .compatible = "thead,th1520", .data = &thead_th1520_quirks },
+	{ .compatible = "xuantie,c908x", .data = &xuantie_c908x_quirks },
 	{ },
 };
 

platform/generic/thead/thead_c9xx_extfunc_fastmem.c

@@ -0,0 +1,35 @@
+/*
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include <libfdt.h>
+#include <libfdt_env.h>
+#include <sbi_utils/fdt/fdt_helper.h>
+#include <sbi/riscv_asm.h>
+#include <thead/c9xx_encoding.h>
+
+void thead_c9xx_fastmem_init(void)
+{
+	int offset, len;
+	unsigned long mfastmbal, mfastmbah;
+	const fdt32_t *val;
+
+	void *fdt = fdt_get_address();
+
+	/* Find node offset */
+	offset = fdt_path_offset(fdt, "/fastmem");
+	if (offset < 0)
+		return;
+
+	val = fdt_getprop(fdt, offset, "mfastmba", &len);
+	if (val && len == 8) {
+		mfastmbah = fdt32_to_cpu(val[0]);
+		mfastmbal = fdt32_to_cpu(val[1]);
+#if __riscv_xlen == 32
+		csr_write(THEAD_C9XX_CSR_MFASTMBA, mfastmbal);
+		csr_write(THEAD_C9XX_CSR_MFASTMBAH, mfastmbah);
+#else
+		csr_write(THEAD_C9XX_CSR_MFASTMBA, mfastmbah << 32 | mfastmbal);
+#endif
+	}
+}