Re: [PATCH] riscv: add SBI SUSP extension support

[Andrew Jones]

On Thu, Jul 20, 2023 at 07:31:42AM +0100, Conor Dooley wrote:
> Hey Woody,
> 
> On Thu, Jul 20, 2023 at 08:23:19AM +0800, Woody Zhang wrote:
> > RISC-V SBI spec 2.0 [1] introduces System Suspend Extension which can be
> > used to suspend the platform via SBI firmware.
> > 
> > This patch can be tested on Qemu with recent OpenSBI with
> > `system-suspend-test` enabled like [2] in DTB.
> > 
> > [1] https://github.com/riscv-non-isa/riscv-sbi-doc/blob/master/riscv-sbi.adoc
> > [2] https://github.com/woodyzhang666/qemu/commit/e4a5120133c1dc354e6ac437ec1f870f6c0f6d05
> > 
> > Signed-off-by: Woody Zhang <woodylab@xxxxxxxxxxx>
> > ---
> >  arch/riscv/include/asm/sbi.h | 10 ++++++++++
> >  arch/riscv/kernel/sbi.c      | 26 ++++++++++++++++++++++++++
> 
> There's prior art here, that is seemingly more complete:
> https://lore.kernel.org/all/20230118180338.6484-2-ajones@xxxxxxxxxxxxxxxx/
> IIRC, the reason it is still in RFC status is that the 2.0 SBI spec is
> not yet frozen, so this cannot be merged.

Yup, I'll repost with the RFC dropped as soon as 2.0 is frozen.

Thanks,
drew

> 
> Thanks,
> Conor.
> 
> >  2 files changed, 36 insertions(+)
> > 
> > diff --git a/arch/riscv/include/asm/sbi.h b/arch/riscv/include/asm/sbi.h
> > index 5b4a1bf5f439..3b04016da671 100644
> > --- a/arch/riscv/include/asm/sbi.h
> > +++ b/arch/riscv/include/asm/sbi.h
> > @@ -30,6 +30,7 @@ enum sbi_ext_id {
> >  	SBI_EXT_HSM = 0x48534D,
> >  	SBI_EXT_SRST = 0x53525354,
> >  	SBI_EXT_PMU = 0x504D55,
> > +	SBI_EXT_SUSP = 0x53555350,
> >  
> >  	/* Experimentals extensions must lie within this range */
> >  	SBI_EXT_EXPERIMENTAL_START = 0x08000000,
> > @@ -236,6 +237,15 @@ enum sbi_pmu_ctr_type {
> >  /* Flags defined for counter stop function */
> >  #define SBI_PMU_STOP_FLAG_RESET (1 << 0)
> >  
> > +enum sbi_ext_susp_fid {
> > +	SBI_EXT_SUSP_SYSTEM_SUSPEND = 0,
> > +};
> > +
> > +/* SBI suspend sleep types */
> > +enum sbi_susp_sleep_type {
> > +	SBI_SUSP_SLEEP_TYPE_SUSPEND = 0x0,
> > +};
> > +
> >  #define SBI_SPEC_VERSION_DEFAULT	0x1
> >  #define SBI_SPEC_VERSION_MAJOR_SHIFT	24
> >  #define SBI_SPEC_VERSION_MAJOR_MASK	0x7f
> > diff --git a/arch/riscv/kernel/sbi.c b/arch/riscv/kernel/sbi.c
> > index c672c8ba9a2a..9a68959f9f18 100644
> > --- a/arch/riscv/kernel/sbi.c
> > +++ b/arch/riscv/kernel/sbi.c
> > @@ -9,8 +9,10 @@
> >  #include <linux/init.h>
> >  #include <linux/pm.h>
> >  #include <linux/reboot.h>
> > +#include <linux/suspend.h>
> >  #include <asm/sbi.h>
> >  #include <asm/smp.h>
> > +#include <asm/suspend.h>
> >  
> >  /* default SBI version is 0.1 */
> >  unsigned long sbi_spec_version __ro_after_init = SBI_SPEC_VERSION_DEFAULT;
> > @@ -520,6 +522,26 @@ static void sbi_srst_power_off(void)
> >  		       SBI_SRST_RESET_REASON_NONE);
> >  }
> >  
> > +static int sbi_system_suspend(unsigned long arg,
> > +		unsigned long resume_entry, unsigned long context)
> > +{
> > +	struct sbiret ret = {0};
> > +
> > +	ret = sbi_ecall(SBI_EXT_SUSP, SBI_EXT_SUSP_SYSTEM_SUSPEND,
> > +			SBI_SUSP_SLEEP_TYPE_SUSPEND, resume_entry, context, 0, 0, 0);
> > +	return ret.error;
> > +}
> > +
> > +static int sbi_system_suspend_enter(suspend_state_t state)
> > +{
> > +	return cpu_suspend(0, sbi_system_suspend);
> > +}
> > +
> > +static const struct platform_suspend_ops sbi_suspend_ops = {
> > +	.valid          = suspend_valid_only_mem,
> > +	.enter          = sbi_system_suspend_enter,
> > +};
> > +
> >  /**
> >   * sbi_probe_extension() - Check if an SBI extension ID is supported or not.
> >   * @extid: The extension ID to be probed.
> > @@ -624,6 +646,10 @@ void __init sbi_init(void)
> >  			sbi_srst_reboot_nb.priority = 192;
> >  			register_restart_handler(&sbi_srst_reboot_nb);
> >  		}
> > +		if (sbi_probe_extension(SBI_EXT_SUSP)) {
> > +			pr_info("SBI SUSP extension detected\n");
> > +			suspend_set_ops(&sbi_suspend_ops);
> > +		}
> >  	} else {
> >  		__sbi_set_timer = __sbi_set_timer_v01;
> >  		__sbi_send_ipi	= __sbi_send_ipi_v01;
> > -- 
> > 2.39.2
> > 



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