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From: Anup Patel <anup@brainfault.org>
To: Atish Patra <atishp@rivosinc.com>
Cc: "linux-kernel@vger.kernel.org List"
	<linux-kernel@vger.kernel.org>,
	Atish Patra <atishp@atishpatra.org>,
	Damien Le Moal <damien.lemoal@wdc.com>,
	DTML <devicetree@vger.kernel.org>,
	Jisheng Zhang <jszhang@kernel.org>,
	Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>,
	KVM General <kvm@vger.kernel.org>,
	"open list:KERNEL VIRTUAL MACHINE FOR RISC-V (KVM/riscv)" 
	<kvm-riscv@lists.infradead.org>,
	linux-riscv <linux-riscv@lists.infradead.org>,
	Palmer Dabbelt <palmer@dabbelt.com>,
	Paul Walmsley <paul.walmsley@sifive.com>,
	Rob Herring <robh+dt@kernel.org>
Subject: Re: [PATCH v3 3/4] RISC-V: Prefer sstc extension if available
Date: Tue, 24 May 2022 17:00:15 +0530	[thread overview]
Message-ID: <CAAhSdy0wbokRNZrXYcARKx=DpGfQ5gFGJ_1K26U0W99-jZcM5g@mail.gmail.com> (raw)
In-Reply-To: <20220426185245.281182-4-atishp@rivosinc.com>

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

WARNING: multiple messages have this Message-ID
From: Anup Patel <anup@brainfault.org>
To: Atish Patra <atishp@rivosinc.com>
Cc: "linux-kernel@vger.kernel.org List"
	<linux-kernel@vger.kernel.org>,
	Atish Patra <atishp@atishpatra.org>,
	 Damien Le Moal <damien.lemoal@wdc.com>,
	DTML <devicetree@vger.kernel.org>,
	 Jisheng Zhang <jszhang@kernel.org>,
	 Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>,
	KVM General <kvm@vger.kernel.org>,
	 "open list:KERNEL VIRTUAL MACHINE FOR RISC-V (KVM/riscv)"
	<kvm-riscv@lists.infradead.org>,
	 linux-riscv <linux-riscv@lists.infradead.org>,
	Palmer Dabbelt <palmer@dabbelt.com>,
	 Paul Walmsley <paul.walmsley@sifive.com>,
	Rob Herring <robh+dt@kernel.org>
Subject: Re: [PATCH v3 3/4] RISC-V: Prefer sstc extension if available
Date: Tue, 24 May 2022 17:00:15 +0530	[thread overview]
Message-ID: <CAAhSdy0wbokRNZrXYcARKx=DpGfQ5gFGJ_1K26U0W99-jZcM5g@mail.gmail.com> (raw)
In-Reply-To: <20220426185245.281182-4-atishp@rivosinc.com>

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

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linux-riscv mailing list
linux-riscv@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-riscv

  reply	other threads:[~2022-05-24 11:30 UTC|newest]

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-04-26 18:52 [PATCH v3 0/4] Add Sstc extension support Atish Patra
2022-04-26 18:52 ` Atish Patra
2022-04-26 18:52 ` [PATCH v3 1/4] RISC-V: Add SSTC extension CSR details Atish Patra
2022-04-26 18:52   ` Atish Patra
2022-05-24 11:24   ` Anup Patel
2022-05-24 11:24     ` Anup Patel
2022-04-26 18:52 ` [PATCH v3 2/4] RISC-V: Enable sstc extension parsing from DT Atish Patra
2022-04-26 18:52   ` Atish Patra
2022-05-24 11:25   ` Anup Patel
2022-05-24 11:25     ` Anup Patel
2022-04-26 18:52 ` [PATCH v3 3/4] RISC-V: Prefer sstc extension if available Atish Patra
2022-04-26 18:52   ` Atish Patra
2022-05-24 11:30   ` Anup Patel [this message]
2022-05-24 11:30     ` Anup Patel
2022-04-26 18:52 ` [PATCH v3 4/4] RISC-V: KVM: Support sstc extension Atish Patra
2022-04-26 18:52   ` Atish Patra
2022-04-26 21:10   ` Jessica Clarke
2022-04-26 21:10     ` Jessica Clarke
2022-05-08  7:49     ` Atish Patra
2022-05-08  7:49       ` Atish Patra
2022-05-24 11:39   ` Anup Patel
2022-05-24 11:39     ` Anup Patel

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