[PATCH v2 05/11] riscv: Add option to disable writes to mcounteren

[Sean Anderson <seanga2@gmail.com>]

On the kendryte k210, writes to mcounteren result in an illegal instruction
exception.

Signed-off-by: Sean Anderson <seanga2@gmail.com>
---
Changes for v2:
 Moved forward in the patch series

 arch/riscv/Kconfig   | 3 +++
 arch/riscv/cpu/cpu.c | 2 ++
 2 files changed, 5 insertions(+)

diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index 9a7b0334c2..4f8c62dcff 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -226,6 +226,9 @@ config XIP
 	  from a NOR flash memory without copying the code to ram.
 	  Say yes here if U-Boot boots from flash directly.
 
+config SYS_RISCV_NOCOUNTER
+	bool "Disable accesses to the mcounteren CSR"
+
 config STACK_SIZE_SHIFT
 	int
 	default 14
diff --git a/arch/riscv/cpu/cpu.c b/arch/riscv/cpu/cpu.c
index e457f6acbf..df9eae663c 100644
--- a/arch/riscv/cpu/cpu.c
+++ b/arch/riscv/cpu/cpu.c
@@ -89,7 +89,9 @@ int arch_cpu_init_dm(void)
 		 * Enable perf counters for cycle, time,
 		 * and instret counters only
 		 */
+#ifndef CONFIG_SYS_RISCV_NOCOUNTER
 		csr_write(CSR_MCOUNTEREN, GENMASK(2, 0));
+#endif
 
 		/* Disable paging */
 		if (supports_extension('s'))
-- 
2.24.1