[PATCH v1 2/3] riscv: cache: Add CBO instructions

[Mayuresh Chitale]

Define CBO inval and flush instructions and use those for the
dcache inval and flush operations respectively.

Signed-off-by: Mayuresh Chitale <mchitale at ventanamicro.com>
---
 arch/riscv/Kconfig             |  4 ++
 arch/riscv/include/asm/cache.h |  3 ++
 arch/riscv/lib/cache.c         | 90 ++++++++++++++++++++++++++++++++++
 3 files changed, 97 insertions(+)

diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index fa3b016c52..0f89d07be7 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -310,6 +310,10 @@ endmenu
 config RISCV_ISA_A
 	def_bool y
 
+config RISCV_ISA_ZICBOM
+	bool "Zicbom support"
+	depends on !SYS_DISABLE_DCACHE_OPS
+
 config DMA_ADDR_T_64BIT
 	bool
 	default y if 64BIT
diff --git a/arch/riscv/include/asm/cache.h b/arch/riscv/include/asm/cache.h
index 874963d731..42dbce5b4f 100644
--- a/arch/riscv/include/asm/cache.h
+++ b/arch/riscv/include/asm/cache.h
@@ -9,6 +9,9 @@
 
 /* cache */
 void cache_flush(void);
+void riscv_zicbom_init(void);
+void cbo_flush(unsigned long start, unsigned long end);
+void cbo_inval(unsigned long start, unsigned long end);
 
 /*
  * The current upper bound for RISCV L1 data cache line sizes is 32 bytes.
diff --git a/arch/riscv/lib/cache.c b/arch/riscv/lib/cache.c
index afad7e117f..456353d9c1 100644
--- a/arch/riscv/lib/cache.c
+++ b/arch/riscv/lib/cache.c
@@ -5,6 +5,95 @@
  */
 
 #include <cpu_func.h>
+#include <dm.h>
+#include <asm/insn-def.h>
+#include <linux/const.h>
+
+#define CBO_INVAL(base)						\
+	INSN_I(OPCODE_MISC_MEM, FUNC3(2), __RD(0),		\
+	       RS1(base), SIMM12(0))
+#define CBO_CLEAN(base)						\
+	INSN_I(OPCODE_MISC_MEM, FUNC3(2), __RD(0),		\
+	       RS1(base), SIMM12(1))
+#define CBO_FLUSH(base)						\
+	INSN_I(OPCODE_MISC_MEM, FUNC3(2), __RD(0),		\
+	       RS1(base), SIMM12(2))
+enum {
+	CBO_CLEAN,
+	CBO_FLUSH,
+	CBO_INVAL
+} riscv_cbo_ops;
+static int zicbom_block_size;
+
+static inline void do_cbo_clean(unsigned long base)
+{
+	asm volatile ("add a0, %0, zero\n" CBO_CLEAN(%0) ::
+		      "r"(base) : "memory");
+}
+
+static inline void do_cbo_flush(unsigned long base)
+{
+	asm volatile ("add a0, %0, zero\n" CBO_FLUSH(%0) ::
+		      "r"(base) : "memory");
+}
+
+static inline void do_cbo_inval(unsigned long base)
+{
+	asm volatile ("add a0, %0, zero\n" CBO_INVAL(%0) ::
+		      "r"(base) : "memory");
+}
+
+static void cbo_op(int op_type, unsigned long start,
+		   unsigned long end)
+{
+	unsigned long op_size = end - start, size = 0;
+	void (*fn)(unsigned long base);
+
+	switch (op_type) {
+	case CBO_CLEAN:
+		fn = do_cbo_clean;
+		break;
+	case CBO_FLUSH:
+		fn = do_cbo_flush;
+		break;
+	case CBO_INVAL:
+		fn = do_cbo_inval;
+		break;
+	}
+	start &= ~(UL(zicbom_block_size - 1));
+	while (size < op_size) {
+		fn(start + size);
+		size += zicbom_block_size;
+	}
+}
+
+void cbo_flush(unsigned long start, unsigned long end)
+{
+	if (zicbom_block_size)
+		cbo_op(CBO_FLUSH, start, end);
+}
+
+void cbo_inval(unsigned long start, unsigned long end)
+{
+	if (zicbom_block_size)
+		cbo_op(CBO_INVAL, start, end);
+}
+
+void riscv_zicbom_init(void)
+{
+	struct udevice *dev;
+
+	if (!CONFIG_IS_ENABLED(RISCV_ISA_ZICBOM))
+		return;
+
+	uclass_first_device(UCLASS_CPU, &dev);
+	if (!dev) {
+		log_err("Failed to get cpu device!\n");
+		return;
+	}
+
+	(void)dev_read_u32(dev, "riscv,cbom-block-size", &zicbom_block_size);
+}
 
 void invalidate_icache_all(void)
 {
@@ -72,4 +161,5 @@ __weak int dcache_status(void)
 
 __weak void enable_caches(void)
 {
+	puts("WARNING: Caches not enabled\n");
 }
-- 
2.34.1