From: Anup Patel anup@brainfault.org
This adds an implementation of riscv_get_time() API that is using rdtime instruction.
This is the case for S-mode U-Boot, and is useful for processors that support rdtime in M-mode too.
Signed-off-by: Anup Patel anup@brainfault.org Signed-off-by: Bin Meng bmeng.cn@gmail.com Reviewed-by: Lukas Auer lukas.auer@aisec.fraunhofer.de
---
Changes in v3: None Changes in v2: - incorporated and reworked Anup's S-mode timer patch @ http://patchwork.ozlabs.org/patch/1006663/
arch/riscv/Kconfig | 8 ++++++++ arch/riscv/lib/Makefile | 1 + arch/riscv/lib/rdtime.c | 38 ++++++++++++++++++++++++++++++++++++++ 3 files changed, 47 insertions(+) create mode 100644 arch/riscv/lib/rdtime.c
diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig index f513f52..7dc6e3f 100644 --- a/arch/riscv/Kconfig +++ b/arch/riscv/Kconfig @@ -104,4 +104,12 @@ config SIFIVE_CLINT The SiFive CLINT block holds memory-mapped control and status registers associated with software and timer interrupts.
+config RISCV_RDTIME + bool + default y if RISCV_SMODE + help + The provides the riscv_get_time() API that is implemented using the + standard rdtime instruction. This is the case for S-mode U-Boot, and + is useful for processors that support rdtime in M-mode too. + endmenu diff --git a/arch/riscv/lib/Makefile b/arch/riscv/lib/Makefile index b13c876..edfa616 100644 --- a/arch/riscv/lib/Makefile +++ b/arch/riscv/lib/Makefile @@ -9,6 +9,7 @@ obj-$(CONFIG_CMD_BOOTM) += bootm.o obj-$(CONFIG_CMD_GO) += boot.o obj-y += cache.o +obj-$(CONFIG_RISCV_RDTIME) += rdtime.o obj-$(CONFIG_SIFIVE_CLINT) += sifive_clint.o obj-y += interrupts.o obj-y += reset.o diff --git a/arch/riscv/lib/rdtime.c b/arch/riscv/lib/rdtime.c new file mode 100644 index 0000000..e128d7f --- /dev/null +++ b/arch/riscv/lib/rdtime.c @@ -0,0 +1,38 @@ +// SPDX-License-Identifier: GPL-2.0+ +/* + * Copyright (C) 2018, Anup Patel anup@brainfault.org + * Copyright (C) 2018, Bin Meng bmeng.cn@gmail.com + * + * The riscv_get_time() API implementation that is using the + * standard rdtime instruction. + */ + +#include <common.h> + +/* Implement the API required by RISC-V timer driver */ +int riscv_get_time(u64 *time) +{ +#ifdef CONFIG_64BIT + u64 n; + + __asm__ __volatile__ ( + "rdtime %0" + : "=r" (n)); + + *time = n; +#else + u32 lo, hi, tmp; + + __asm__ __volatile__ ( + "1:\n" + "rdtimeh %0\n" + "rdtime %1\n" + "rdtimeh %2\n" + "bne %0, %2, 1b" + : "=&r" (hi), "=&r" (lo), "=&r" (tmp)); + + *time = ((u64)hi << 32) | lo; +#endif + + return 0; +}