linux-kernel - Re: [PATCH V2 17/21] RISC-V: time.c: Add ACPI support for time

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Message-ID: <20230220195808.reyuclvefujucpsq@orel>
Date:   Mon, 20 Feb 2023 20:58:08 +0100
From:   Andrew Jones <ajones@...tanamicro.com>
To:     Sunil V L <sunilvl@...tanamicro.com>
Cc:     Palmer Dabbelt <palmer@...belt.com>,
        Albert Ou <aou@...s.berkeley.edu>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        "Rafael J . Wysocki" <rafael@...nel.org>,
        Len Brown <lenb@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Marc Zyngier <maz@...nel.org>,
        Jonathan Corbet <corbet@....net>,
        linux-riscv@...ts.infradead.org, linux-acpi@...r.kernel.org,
        linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
        Conor Dooley <conor.dooley@...rochip.com>,
        Anup Patel <apatel@...tanamicro.com>,
        Atish Patra <atishp@...osinc.com>,
        "Rafael J . Wysocki" <rafael.j.wysocki@...el.com>
Subject: Re: [PATCH V2 17/21] RISC-V: time.c: Add ACPI support for time_init()

On Thu, Feb 16, 2023 at 11:50:39PM +0530, Sunil V L wrote:
> On ACPI based platforms, timer related information is
> available in RHCT. Add ACPI based probe support to the
> timer initialization.
> 
> Signed-off-by: Sunil V L <sunilvl@...tanamicro.com>
> Acked-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
> ---
>  arch/riscv/kernel/time.c | 25 +++++++++++++++++++------
>  1 file changed, 19 insertions(+), 6 deletions(-)
> 
> diff --git a/arch/riscv/kernel/time.c b/arch/riscv/kernel/time.c
> index 1cf21db4fcc7..e49b897fc657 100644
> --- a/arch/riscv/kernel/time.c
> +++ b/arch/riscv/kernel/time.c
> @@ -4,6 +4,7 @@
>   * Copyright (C) 2017 SiFive
>   */
>  
> +#include <linux/acpi.h>
>  #include <linux/of_clk.h>
>  #include <linux/clockchips.h>
>  #include <linux/clocksource.h>
> @@ -18,17 +19,29 @@ EXPORT_SYMBOL_GPL(riscv_timebase);
>  void __init time_init(void)
>  {
>  	struct device_node *cpu;
> +	struct acpi_table_rhct *rhct;
> +	acpi_status status;
>  	u32 prop;
>  
> -	cpu = of_find_node_by_path("/cpus");
> -	if (!cpu || of_property_read_u32(cpu, "timebase-frequency", &prop))
> -		panic(KERN_WARNING "RISC-V system with no 'timebase-frequency' in DTS\n");
> -	of_node_put(cpu);
> -	riscv_timebase = prop;
> +	if (acpi_disabled) {
> +		cpu = of_find_node_by_path("/cpus");
> +		if (!cpu || of_property_read_u32(cpu, "timebase-frequency", &prop))
> +			panic("RISC-V system with no 'timebase-frequency' in DTS\n");
> +		of_node_put(cpu);
> +		riscv_timebase = prop;
> +	} else {
> +		status = acpi_get_table(ACPI_SIG_RHCT, 0, (struct acpi_table_header **)&rhct);
> +		if (ACPI_FAILURE(status))
> +			panic("RISC-V ACPI system with no RHCT table\n");
> +		riscv_timebase = rhct->time_base_freq;
> +		acpi_put_table((struct acpi_table_header *)rhct);
> +	}
>  
>  	lpj_fine = riscv_timebase / HZ;
>  
> -	of_clk_init(NULL);
> +	if (acpi_disabled)
> +		of_clk_init(NULL);

I think we should be able to move of_clk_init() up into the acpi_disabled
arm rather than add another if here.

> +
>  	timer_probe();
>  
>  	tick_setup_hrtimer_broadcast();
> -- 
> 2.34.1
> 

Otherwise,

Reviewed-by: Andrew Jones <ajones@...tanamicro.com>