riscv: cache: Add CBO instructions

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

Signed-off-by: Mayuresh Chitale <mchitale@ventanamicro.com>
Reviewed-by: Leo Yu-Chi Liang <ycliang@andestech.com>

arch/riscv/Kconfig

@@ -319,6 +319,10 @@ config RISCV_ISA_A
 	help
 	  Adds "A" to the ISA string passed to the compiler.
 
+config RISCV_ISA_ZICBOM
+	bool "Zicbom support"
+	depends on !SYS_DISABLE_DCACHE_OPS
+
 config DMA_ADDR_T_64BIT
 	bool
 	default y if 64BIT

arch/riscv/lib/cache.c

@@ -5,6 +5,98 @@
  */
 
 #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);
+}
+
+static int riscv_zicbom_init(void)
+{
+	struct udevice *dev;
+
+	if (!CONFIG_IS_ENABLED(RISCV_ISA_ZICBOM) || zicbom_block_size)
+		return 1;
+
+	uclass_first_device(UCLASS_CPU, &dev);
+	if (!dev) {
+		log_debug("Failed to get cpu device!\n");
+		return 0;
+	}
+
+	if (dev_read_u32(dev, "riscv,cbom-block-size", &zicbom_block_size))
+		log_debug("riscv,cbom-block-size DT property not present\n");
+
+	return zicbom_block_size;
+}
 
 void invalidate_icache_all(void)
 {
@@ -17,6 +109,7 @@ __weak void flush_dcache_all(void)
 
 __weak void flush_dcache_range(unsigned long start, unsigned long end)
 {
+	cbo_flush(start, end);
 }
 
 __weak void invalidate_icache_range(unsigned long start, unsigned long end)
@@ -30,6 +123,7 @@ __weak void invalidate_icache_range(unsigned long start, unsigned long end)
 
 __weak void invalidate_dcache_range(unsigned long start, unsigned long end)
 {
+	cbo_inval(start, end);
 }
 
 void cache_flush(void)
@@ -72,4 +166,6 @@ __weak int dcache_status(void)
 
 __weak void enable_caches(void)
 {
+	if (!riscv_zicbom_init())
+		log_info("Zicbom not initialized.\n");
 }