From 4f9bbcefa142862782275a4b29f390ca8d8b9242 Mon Sep 17 00:00:00 2001 From: Christoph Hellwig Date: Mon, 28 Oct 2019 13:10:37 +0100 Subject: [PATCH] riscv: add support for MMIO access to the timer registers When running in M-mode we can't use the SBI to set the timer, and don't have access to the time CSR as that usually is emulated by M-mode. Instead provide code that directly accesses the MMIO for the timer. Signed-off-by: Christoph Hellwig Reviewed-by: Anup Patel Acked-by: Thomas Gleixner # for drivers/clocksource [paul.walmsley@sifive.com: updated to apply; fixed checkpatch issue; timex.h now includes asm/mmio.h to resolve header file problems] Signed-off-by: Paul Walmsley --- arch/riscv/include/asm/sbi.h | 3 ++- arch/riscv/include/asm/timex.h | 19 +++++++++++++++++-- drivers/clocksource/timer-riscv.c | 23 +++++++++++++++++++---- 3 files changed, 38 insertions(+), 7 deletions(-) diff --git a/arch/riscv/include/asm/sbi.h b/arch/riscv/include/asm/sbi.h index 204af71..8e14d48 100644 --- a/arch/riscv/include/asm/sbi.h +++ b/arch/riscv/include/asm/sbi.h @@ -95,7 +95,8 @@ static inline void sbi_remote_sfence_vma_asid(const unsigned long *hart_mask, SBI_CALL_4(SBI_REMOTE_SFENCE_VMA_ASID, hart_mask, start, size, asid); } #else /* CONFIG_RISCV_SBI */ -/* stub for code that is only reachable under IS_ENABLED(CONFIG_RISCV_SBI): */ +/* stubs for code that is only reachable under IS_ENABLED(CONFIG_RISCV_SBI): */ +void sbi_set_timer(uint64_t stime_value); void sbi_remote_fence_i(const unsigned long *hart_mask); #endif /* CONFIG_RISCV_SBI */ #endif /* _ASM_RISCV_SBI_H */ diff --git a/arch/riscv/include/asm/timex.h b/arch/riscv/include/asm/timex.h index c7ef131..bad2a7c 100644 --- a/arch/riscv/include/asm/timex.h +++ b/arch/riscv/include/asm/timex.h @@ -7,12 +7,25 @@ #define _ASM_RISCV_TIMEX_H #include +#include typedef unsigned long cycles_t; +extern u64 __iomem *riscv_time_val; +extern u64 __iomem *riscv_time_cmp; + +#ifdef CONFIG_64BIT +#define mmio_get_cycles() readq_relaxed(riscv_time_val) +#else +#define mmio_get_cycles() readl_relaxed(riscv_time_val) +#define mmio_get_cycles_hi() readl_relaxed(((u32 *)riscv_time_val) + 1) +#endif + static inline cycles_t get_cycles(void) { - return csr_read(CSR_TIME); + if (IS_ENABLED(CONFIG_RISCV_SBI)) + return csr_read(CSR_TIME); + return mmio_get_cycles(); } #define get_cycles get_cycles @@ -24,7 +37,9 @@ static inline u64 get_cycles64(void) #else /* CONFIG_64BIT */ static inline u32 get_cycles_hi(void) { - return csr_read(CSR_TIMEH); + if (IS_ENABLED(CONFIG_RISCV_SBI)) + return csr_read(CSR_TIMEH); + return mmio_get_cycles_hi(); } static inline u64 get_cycles64(void) diff --git a/drivers/clocksource/timer-riscv.c b/drivers/clocksource/timer-riscv.c index d083bfb..4e54856 100644 --- a/drivers/clocksource/timer-riscv.c +++ b/drivers/clocksource/timer-riscv.c @@ -3,9 +3,9 @@ * Copyright (C) 2012 Regents of the University of California * Copyright (C) 2017 SiFive * - * All RISC-V systems have a timer attached to every hart. These timers can be - * read from the "time" and "timeh" CSRs, and can use the SBI to setup - * events. + * All RISC-V systems have a timer attached to every hart. These timers can + * either be read from the "time" and "timeh" CSRs, and can use the SBI to + * setup events, or directly accessed using MMIO registers. */ #include #include @@ -13,14 +13,29 @@ #include #include #include +#include #include #include +u64 __iomem *riscv_time_cmp; +u64 __iomem *riscv_time_val; + +static inline void mmio_set_timer(u64 val) +{ + void __iomem *r; + + r = riscv_time_cmp + cpuid_to_hartid_map(smp_processor_id()); + writeq_relaxed(val, r); +} + static int riscv_clock_next_event(unsigned long delta, struct clock_event_device *ce) { csr_set(CSR_IE, IE_TIE); - sbi_set_timer(get_cycles64() + delta); + if (IS_ENABLED(CONFIG_RISCV_SBI)) + sbi_set_timer(get_cycles64() + delta); + else + mmio_set_timer(get_cycles64() + delta); return 0; } -- 2.7.4