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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 <hch@lst.de> Reviewed-by: Anup Patel <anup@brainfault.org> Acked-by: Thomas Gleixner <tglx@linutronix.de> # 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 <paul.walmsley@sifive.com>
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@ -95,7 +95,8 @@ static inline void sbi_remote_sfence_vma_asid(const unsigned long *hart_mask,
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SBI_CALL_4(SBI_REMOTE_SFENCE_VMA_ASID, hart_mask, start, size, asid);
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}
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#else /* CONFIG_RISCV_SBI */
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/* stub for code that is only reachable under IS_ENABLED(CONFIG_RISCV_SBI): */
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/* stubs for code that is only reachable under IS_ENABLED(CONFIG_RISCV_SBI): */
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void sbi_set_timer(uint64_t stime_value);
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void sbi_remote_fence_i(const unsigned long *hart_mask);
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#endif /* CONFIG_RISCV_SBI */
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#endif /* _ASM_RISCV_SBI_H */
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@ -7,12 +7,25 @@
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#define _ASM_RISCV_TIMEX_H
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#include <asm/csr.h>
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#include <asm/mmio.h>
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typedef unsigned long cycles_t;
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extern u64 __iomem *riscv_time_val;
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extern u64 __iomem *riscv_time_cmp;
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#ifdef CONFIG_64BIT
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#define mmio_get_cycles() readq_relaxed(riscv_time_val)
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#else
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#define mmio_get_cycles() readl_relaxed(riscv_time_val)
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#define mmio_get_cycles_hi() readl_relaxed(((u32 *)riscv_time_val) + 1)
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#endif
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static inline cycles_t get_cycles(void)
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{
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return csr_read(CSR_TIME);
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if (IS_ENABLED(CONFIG_RISCV_SBI))
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return csr_read(CSR_TIME);
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return mmio_get_cycles();
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}
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#define get_cycles get_cycles
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@ -24,7 +37,9 @@ static inline u64 get_cycles64(void)
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#else /* CONFIG_64BIT */
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static inline u32 get_cycles_hi(void)
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{
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return csr_read(CSR_TIMEH);
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if (IS_ENABLED(CONFIG_RISCV_SBI))
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return csr_read(CSR_TIMEH);
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return mmio_get_cycles_hi();
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}
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static inline u64 get_cycles64(void)
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@ -3,9 +3,9 @@
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* Copyright (C) 2012 Regents of the University of California
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* Copyright (C) 2017 SiFive
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*
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* All RISC-V systems have a timer attached to every hart. These timers can be
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* read from the "time" and "timeh" CSRs, and can use the SBI to setup
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* events.
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* All RISC-V systems have a timer attached to every hart. These timers can
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* either be read from the "time" and "timeh" CSRs, and can use the SBI to
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* setup events, or directly accessed using MMIO registers.
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*/
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#include <linux/clocksource.h>
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#include <linux/clockchips.h>
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@ -13,14 +13,29 @@
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#include <linux/delay.h>
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#include <linux/irq.h>
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#include <linux/sched_clock.h>
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#include <linux/io-64-nonatomic-lo-hi.h>
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#include <asm/smp.h>
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#include <asm/sbi.h>
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u64 __iomem *riscv_time_cmp;
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u64 __iomem *riscv_time_val;
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static inline void mmio_set_timer(u64 val)
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{
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void __iomem *r;
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r = riscv_time_cmp + cpuid_to_hartid_map(smp_processor_id());
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writeq_relaxed(val, r);
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}
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static int riscv_clock_next_event(unsigned long delta,
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struct clock_event_device *ce)
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{
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csr_set(CSR_IE, IE_TIE);
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sbi_set_timer(get_cycles64() + delta);
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if (IS_ENABLED(CONFIG_RISCV_SBI))
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sbi_set_timer(get_cycles64() + delta);
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else
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mmio_set_timer(get_cycles64() + delta);
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return 0;
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}
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