[PATCH v6 04/21] RISC-V: Define indirect CSR access helpers

[Atish Patra]

From: Atish Patra <atishp at rivosinc.com>

The indriect CSR requires multiple instructions to read/write CSR.
Add a few helper functions for ease of usage.

Signed-off-by: Atish Patra <atishp at rivosinc.com>
---
 arch/riscv/include/asm/csr_ind.h | 44 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 44 insertions(+)

diff --git a/arch/riscv/include/asm/csr_ind.h b/arch/riscv/include/asm/csr_ind.h
new file mode 100644
index 000000000000..6fd7d44dc640
--- /dev/null
+++ b/arch/riscv/include/asm/csr_ind.h
@@ -0,0 +1,44 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (C) 2024 Rivos Inc.
+ */
+
+#ifndef _ASM_RISCV_CSR_IND_H
+#define _ASM_RISCV_CSR_IND_H
+
+#include <linux/irqflags.h>
+
+#include <asm/csr.h>
+
+#define csr_ind_read(iregcsr, iselbase, iseloff) ({		\
+	unsigned long __value = 0;				\
+	unsigned long __flags;					\
+	local_irq_save(__flags);				\
+	csr_write(CSR_ISELECT, (iselbase) + (iseloff));		\
+	__value = csr_read(iregcsr);				\
+	local_irq_restore(__flags);				\
+	__value;						\
+})
+
+#define csr_ind_write(iregcsr, iselbase, iseloff, value) ({	\
+	unsigned long __flags;					\
+	local_irq_save(__flags);				\
+	csr_write(CSR_ISELECT, (iselbase) + (iseloff));		\
+	csr_write(iregcsr, (value));				\
+	local_irq_restore(__flags);				\
+})
+
+#define csr_ind_warl(iregcsr, iselbase, iseloff, warl_val) ({	\
+	unsigned long __old_val = 0, __value = 0;		\
+	unsigned long __flags;					\
+	local_irq_save(__flags);				\
+	csr_write(CSR_ISELECT, (iselbase) + (iseloff));		\
+	__old_val = csr_read(iregcsr);				\
+	csr_write(iregcsr, (warl_val));				\
+	__value = csr_read(iregcsr);				\
+	csr_write(iregcsr, __old_val);				\
+	local_irq_restore(__flags);				\
+	__value;						\
+})
+
+#endif

-- 
2.53.0-Meta