| Message ID | 20220426185245.281182-4-atishp@rivosinc.com |
|---|---|
| State | Superseded |
| Headers | show |
| Series | Add Sstc extension support | expand |
On Wed, Apr 27, 2022 at 12:23 AM Atish Patra <atishp@rivosinc.com> wrote: > > RISC-V ISA has sstc extension which allows updating the next clock event > via a CSR (stimecmp) instead of an SBI call. This should happen dynamically > if sstc extension is available. Otherwise, it will fallback to SBI call > to maintain backward compatibility. > > Signed-off-by: Atish Patra <atishp@rivosinc.com> > --- > drivers/clocksource/timer-riscv.c | 21 ++++++++++++++++++++- > 1 file changed, 20 insertions(+), 1 deletion(-) > > diff --git a/drivers/clocksource/timer-riscv.c b/drivers/clocksource/timer-riscv.c > index 1767f8bf2013..d9398ae84a20 100644 > --- a/drivers/clocksource/timer-riscv.c > +++ b/drivers/clocksource/timer-riscv.c > @@ -23,11 +23,24 @@ Add "#define pr_fmt(fmt)" here since you are using pr_info(...) > #include <asm/sbi.h> > #include <asm/timex.h> > > +static DEFINE_STATIC_KEY_FALSE(riscv_sstc_available); > + > static int riscv_clock_next_event(unsigned long delta, > struct clock_event_device *ce) > { > + uint64_t next_tval = get_cycles64() + delta; Use "u64" here to be consistent with other parts of the kernel. > + > csr_set(CSR_IE, IE_TIE); > - sbi_set_timer(get_cycles64() + delta); > + if (static_branch_likely(&riscv_sstc_available)) { > +#if __riscv_xlen == 32 Use CONFIG_32BIT here. > + csr_write(CSR_STIMECMP, next_tval & 0xFFFFFFFF); > + csr_write(CSR_STIMECMPH, next_tval >> 32); > +#else > + csr_write(CSR_STIMECMP, next_tval); > +#endif > + } else > + sbi_set_timer(next_tval); > + > return 0; > } > > @@ -165,6 +178,12 @@ static int __init riscv_timer_init_dt(struct device_node *n) > if (error) > pr_err("cpu hp setup state failed for RISCV timer [%d]\n", > error); > + > + if (riscv_isa_extension_available(NULL, SSTC)) { > + pr_info("Timer interrupt in S-mode is available via sstc extension\n"); > + static_branch_enable(&riscv_sstc_available); > + } > + > return error; > } > > -- > 2.25.1 > Regards, Anup
diff --git a/drivers/clocksource/timer-riscv.c b/drivers/clocksource/timer-riscv.c index 1767f8bf2013..d9398ae84a20 100644 --- a/drivers/clocksource/timer-riscv.c +++ b/drivers/clocksource/timer-riscv.c @@ -23,11 +23,24 @@ #include <asm/sbi.h> #include <asm/timex.h> +static DEFINE_STATIC_KEY_FALSE(riscv_sstc_available); + static int riscv_clock_next_event(unsigned long delta, struct clock_event_device *ce) { + uint64_t next_tval = get_cycles64() + delta; + csr_set(CSR_IE, IE_TIE); - sbi_set_timer(get_cycles64() + delta); + if (static_branch_likely(&riscv_sstc_available)) { +#if __riscv_xlen == 32 + csr_write(CSR_STIMECMP, next_tval & 0xFFFFFFFF); + csr_write(CSR_STIMECMPH, next_tval >> 32); +#else + csr_write(CSR_STIMECMP, next_tval); +#endif + } else + sbi_set_timer(next_tval); + return 0; } @@ -165,6 +178,12 @@ static int __init riscv_timer_init_dt(struct device_node *n) if (error) pr_err("cpu hp setup state failed for RISCV timer [%d]\n", error); + + if (riscv_isa_extension_available(NULL, SSTC)) { + pr_info("Timer interrupt in S-mode is available via sstc extension\n"); + static_branch_enable(&riscv_sstc_available); + } + return error; }
RISC-V ISA has sstc extension which allows updating the next clock event via a CSR (stimecmp) instead of an SBI call. This should happen dynamically if sstc extension is available. Otherwise, it will fallback to SBI call to maintain backward compatibility. Signed-off-by: Atish Patra <atishp@rivosinc.com> --- drivers/clocksource/timer-riscv.c | 21 ++++++++++++++++++++- 1 file changed, 20 insertions(+), 1 deletion(-)