[PATCH v2 0/1] riscv: Introduce system suspend support

[PATCH v2 0/1] riscv: Introduce system suspend support

[Andrew Jones]

OpenSBI v1.3 and later supports the SUSP SBI extension which has recently
been frozen with the freezing of SBI 2.0. This one patch series adds
system suspend support to Linux, which implements "suspend-to-RAM". To
use it, build the kernel with CONFIG_SUSPEND, boot on a platform which
supports system suspend, and then issue 'echo mem > /sys/power/state'.
It's also possible to test this Linux support on a platform without
system suspend by using OpenSBI's system suspend test support. To enable
test support add

      opensbi-domains {
          compatible = "opensbi,domain,config";
          system-suspend-test;
      };

to the chosen node of the device tree. With the test node present,
OpenSBI will wait 5 seconds on a suspend and then kick a resume.

Changes for v2:
  - Rebase on v6.7-rc1
  - Added check for SBI spec version 2.0, which is the first ratified
    spec version with SUSP [Conor, Anup]
  - Picked up t-b from Samuel

Changes for v1:
  - Rebase on v6.6-rc1 -- only minor Kconfig change needed

Changes for RFC-v2:
  - RISCV_SBI dependency [Conor]
  - Rename SBI_EXT_SUSP_SUSPEND to SBI_EXT_SUSP_SYSTEM_SUSPEND and
    SBI_SUSP_SLEEP_TYPE_SUSPEND to SBI_SUSP_SLEEP_TYPE_SUSPEND_TO_RAM [Ley Foon]

Andrew Jones (1):
  riscv: sbi: Introduce system suspend support

 arch/riscv/Kconfig           |  6 ++++-
 arch/riscv/include/asm/sbi.h |  9 ++++++++
 arch/riscv/kernel/suspend.c  | 44 ++++++++++++++++++++++++++++++++++++
 3 files changed, 58 insertions(+), 1 deletion(-)

-- 
2.43.0


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[PATCH v2 1/1] riscv: sbi: Introduce system suspend support

[Andrew Jones]

When the SUSP SBI extension is present it implies that the standard
"suspend to RAM" type is available. Wire it up to the generic
platform suspend support, also applying the already present support
for non-retentive CPU suspend. When the kernel is built with
CONFIG_SUSPEND, one can do 'echo mem > /sys/power/state' to suspend.
Resumption will occur when a platform-specific wake-up event arrives.

Signed-off-by: Andrew Jones <ajones@ventanamicro.com>
Tested-by: Samuel Holland <samuel.holland@sifive.com>
---
 arch/riscv/Kconfig           |  6 ++++-
 arch/riscv/include/asm/sbi.h |  9 ++++++++
 arch/riscv/kernel/suspend.c  | 44 ++++++++++++++++++++++++++++++++++++
 3 files changed, 58 insertions(+), 1 deletion(-)

diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index 95a2a06acc6a..385fcad45c47 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -65,7 +65,7 @@ config RISCV
 	select CLINT_TIMER if !MMU
 	select CLONE_BACKWARDS
 	select COMMON_CLK
-	select CPU_PM if CPU_IDLE || HIBERNATION
+	select CPU_PM if CPU_IDLE || HIBERNATION || SUSPEND
 	select EDAC_SUPPORT
 	select FRAME_POINTER if PERF_EVENTS || (FUNCTION_TRACER && !DYNAMIC_FTRACE)
 	select GENERIC_ARCH_TOPOLOGY
@@ -918,9 +918,13 @@ config PORTABLE
 	select MMU
 	select OF
 
+
 config ARCH_PROC_KCORE_TEXT
 	def_bool y
 
+config ARCH_SUSPEND_POSSIBLE
+	def_bool RISCV_SBI
+
 menu "Power management options"
 
 source "kernel/power/Kconfig"
diff --git a/arch/riscv/include/asm/sbi.h b/arch/riscv/include/asm/sbi.h
index 0892f4421bc4..f09356e187df 100644
--- a/arch/riscv/include/asm/sbi.h
+++ b/arch/riscv/include/asm/sbi.h
@@ -29,6 +29,7 @@ enum sbi_ext_id {
 	SBI_EXT_RFENCE = 0x52464E43,
 	SBI_EXT_HSM = 0x48534D,
 	SBI_EXT_SRST = 0x53525354,
+	SBI_EXT_SUSP = 0x53555350,
 	SBI_EXT_PMU = 0x504D55,
 	SBI_EXT_DBCN = 0x4442434E,
 
@@ -114,6 +115,14 @@ enum sbi_srst_reset_reason {
 	SBI_SRST_RESET_REASON_SYS_FAILURE,
 };
 
+enum sbi_ext_susp_fid {
+	SBI_EXT_SUSP_SYSTEM_SUSPEND = 0,
+};
+
+enum sbi_ext_susp_sleep_type {
+	SBI_SUSP_SLEEP_TYPE_SUSPEND_TO_RAM = 0,
+};
+
 enum sbi_ext_pmu_fid {
 	SBI_EXT_PMU_NUM_COUNTERS = 0,
 	SBI_EXT_PMU_COUNTER_GET_INFO,
diff --git a/arch/riscv/kernel/suspend.c b/arch/riscv/kernel/suspend.c
index 3c89b8ec69c4..239509367e42 100644
--- a/arch/riscv/kernel/suspend.c
+++ b/arch/riscv/kernel/suspend.c
@@ -4,8 +4,12 @@
  * Copyright (c) 2022 Ventana Micro Systems Inc.
  */
 
+#define pr_fmt(fmt) "suspend: " fmt
+
 #include <linux/ftrace.h>
+#include <linux/suspend.h>
 #include <asm/csr.h>
+#include <asm/sbi.h>
 #include <asm/suspend.h>
 
 void suspend_save_csrs(struct suspend_context *context)
@@ -85,3 +89,43 @@ int cpu_suspend(unsigned long arg,
 
 	return rc;
 }
+
+#ifdef CONFIG_RISCV_SBI
+static int sbi_system_suspend(unsigned long sleep_type,
+			      unsigned long resume_addr,
+			      unsigned long opaque)
+{
+	struct sbiret ret;
+
+	ret = sbi_ecall(SBI_EXT_SUSP, SBI_EXT_SUSP_SYSTEM_SUSPEND,
+			sleep_type, resume_addr, opaque, 0, 0, 0);
+	if (ret.error)
+		return sbi_err_map_linux_errno(ret.error);
+
+	return ret.value;
+}
+
+static int sbi_system_suspend_enter(suspend_state_t state)
+{
+	return cpu_suspend(SBI_SUSP_SLEEP_TYPE_SUSPEND_TO_RAM, sbi_system_suspend);
+}
+
+static const struct platform_suspend_ops sbi_system_suspend_ops = {
+	.valid = suspend_valid_only_mem,
+	.enter = sbi_system_suspend_enter,
+};
+
+static int __init sbi_system_suspend_init(void)
+{
+	if (sbi_spec_version >= sbi_mk_version(2, 0) &&
+	    sbi_probe_extension(SBI_EXT_SUSP) > 0) {
+		pr_info("SBI SUSP extension detected\n");
+		if (IS_ENABLED(CONFIG_SUSPEND))
+			suspend_set_ops(&sbi_system_suspend_ops);
+	}
+
+	return 0;
+}
+
+arch_initcall(sbi_system_suspend_init);
+#endif /* CONFIG_RISCV_SBI */
-- 
2.43.0


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Re: [PATCH v2 1/1] riscv: sbi: Introduce system suspend support

[Samuel Holland]

Hi Andrew,

On 2023-11-29 5:34 AM, Andrew Jones wrote:
> When the SUSP SBI extension is present it implies that the standard
> "suspend to RAM" type is available. Wire it up to the generic
> platform suspend support, also applying the already present support
> for non-retentive CPU suspend. When the kernel is built with
> CONFIG_SUSPEND, one can do 'echo mem > /sys/power/state' to suspend.
> Resumption will occur when a platform-specific wake-up event arrives.
> 
> Signed-off-by: Andrew Jones <ajones@ventanamicro.com>
> Tested-by: Samuel Holland <samuel.holland@sifive.com>
> ---
>  arch/riscv/Kconfig           |  6 ++++-
>  arch/riscv/include/asm/sbi.h |  9 ++++++++
>  arch/riscv/kernel/suspend.c  | 44 ++++++++++++++++++++++++++++++++++++
>  3 files changed, 58 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
> index 95a2a06acc6a..385fcad45c47 100644
> --- a/arch/riscv/Kconfig
> +++ b/arch/riscv/Kconfig
> @@ -65,7 +65,7 @@ config RISCV
>  	select CLINT_TIMER if !MMU
>  	select CLONE_BACKWARDS
>  	select COMMON_CLK
> -	select CPU_PM if CPU_IDLE || HIBERNATION
> +	select CPU_PM if CPU_IDLE || HIBERNATION || SUSPEND
>  	select EDAC_SUPPORT
>  	select FRAME_POINTER if PERF_EVENTS || (FUNCTION_TRACER && !DYNAMIC_FTRACE)
>  	select GENERIC_ARCH_TOPOLOGY
> @@ -918,9 +918,13 @@ config PORTABLE
>  	select MMU
>  	select OF
>  
> +
>  config ARCH_PROC_KCORE_TEXT
>  	def_bool y
>  
> +config ARCH_SUSPEND_POSSIBLE
> +	def_bool RISCV_SBI
> +

This option was already added by commit c1f048a6bd7d ("riscv: Enable
ARCH_SUSPEND_POSSIBLE for s2idle"), so this hunk is a duplicate.

Regards,
Samuel

>  menu "Power management options"
>  
>  source "kernel/power/Kconfig"
> diff --git a/arch/riscv/include/asm/sbi.h b/arch/riscv/include/asm/sbi.h
> index 0892f4421bc4..f09356e187df 100644
> --- a/arch/riscv/include/asm/sbi.h
> +++ b/arch/riscv/include/asm/sbi.h
> @@ -29,6 +29,7 @@ enum sbi_ext_id {
>  	SBI_EXT_RFENCE = 0x52464E43,
>  	SBI_EXT_HSM = 0x48534D,
>  	SBI_EXT_SRST = 0x53525354,
> +	SBI_EXT_SUSP = 0x53555350,
>  	SBI_EXT_PMU = 0x504D55,
>  	SBI_EXT_DBCN = 0x4442434E,
>  
> @@ -114,6 +115,14 @@ enum sbi_srst_reset_reason {
>  	SBI_SRST_RESET_REASON_SYS_FAILURE,
>  };
>  
> +enum sbi_ext_susp_fid {
> +	SBI_EXT_SUSP_SYSTEM_SUSPEND = 0,
> +};
> +
> +enum sbi_ext_susp_sleep_type {
> +	SBI_SUSP_SLEEP_TYPE_SUSPEND_TO_RAM = 0,
> +};
> +
>  enum sbi_ext_pmu_fid {
>  	SBI_EXT_PMU_NUM_COUNTERS = 0,
>  	SBI_EXT_PMU_COUNTER_GET_INFO,
> diff --git a/arch/riscv/kernel/suspend.c b/arch/riscv/kernel/suspend.c
> index 3c89b8ec69c4..239509367e42 100644
> --- a/arch/riscv/kernel/suspend.c
> +++ b/arch/riscv/kernel/suspend.c
> @@ -4,8 +4,12 @@
>   * Copyright (c) 2022 Ventana Micro Systems Inc.
>   */
>  
> +#define pr_fmt(fmt) "suspend: " fmt
> +
>  #include <linux/ftrace.h>
> +#include <linux/suspend.h>
>  #include <asm/csr.h>
> +#include <asm/sbi.h>
>  #include <asm/suspend.h>
>  
>  void suspend_save_csrs(struct suspend_context *context)
> @@ -85,3 +89,43 @@ int cpu_suspend(unsigned long arg,
>  
>  	return rc;
>  }
> +
> +#ifdef CONFIG_RISCV_SBI
> +static int sbi_system_suspend(unsigned long sleep_type,
> +			      unsigned long resume_addr,
> +			      unsigned long opaque)
> +{
> +	struct sbiret ret;
> +
> +	ret = sbi_ecall(SBI_EXT_SUSP, SBI_EXT_SUSP_SYSTEM_SUSPEND,
> +			sleep_type, resume_addr, opaque, 0, 0, 0);
> +	if (ret.error)
> +		return sbi_err_map_linux_errno(ret.error);
> +
> +	return ret.value;
> +}
> +
> +static int sbi_system_suspend_enter(suspend_state_t state)
> +{
> +	return cpu_suspend(SBI_SUSP_SLEEP_TYPE_SUSPEND_TO_RAM, sbi_system_suspend);
> +}
> +
> +static const struct platform_suspend_ops sbi_system_suspend_ops = {
> +	.valid = suspend_valid_only_mem,
> +	.enter = sbi_system_suspend_enter,
> +};
> +
> +static int __init sbi_system_suspend_init(void)
> +{
> +	if (sbi_spec_version >= sbi_mk_version(2, 0) &&
> +	    sbi_probe_extension(SBI_EXT_SUSP) > 0) {
> +		pr_info("SBI SUSP extension detected\n");
> +		if (IS_ENABLED(CONFIG_SUSPEND))
> +			suspend_set_ops(&sbi_system_suspend_ops);
> +	}
> +
> +	return 0;
> +}
> +
> +arch_initcall(sbi_system_suspend_init);
> +#endif /* CONFIG_RISCV_SBI */


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Re: [PATCH v2 1/1] riscv: sbi: Introduce system suspend support

[Andrew Jones]

On Tue, Dec 05, 2023 at 12:23:07PM -0600, Samuel Holland wrote:
> Hi Andrew,
> 
> On 2023-11-29 5:34 AM, Andrew Jones wrote:
> > When the SUSP SBI extension is present it implies that the standard
> > "suspend to RAM" type is available. Wire it up to the generic
> > platform suspend support, also applying the already present support
> > for non-retentive CPU suspend. When the kernel is built with
> > CONFIG_SUSPEND, one can do 'echo mem > /sys/power/state' to suspend.
> > Resumption will occur when a platform-specific wake-up event arrives.
> > 
> > Signed-off-by: Andrew Jones <ajones@ventanamicro.com>
> > Tested-by: Samuel Holland <samuel.holland@sifive.com>
> > ---
> >  arch/riscv/Kconfig           |  6 ++++-
> >  arch/riscv/include/asm/sbi.h |  9 ++++++++
> >  arch/riscv/kernel/suspend.c  | 44 ++++++++++++++++++++++++++++++++++++
> >  3 files changed, 58 insertions(+), 1 deletion(-)
> > 
> > diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
> > index 95a2a06acc6a..385fcad45c47 100644
> > --- a/arch/riscv/Kconfig
> > +++ b/arch/riscv/Kconfig
> > @@ -65,7 +65,7 @@ config RISCV
> >  	select CLINT_TIMER if !MMU
> >  	select CLONE_BACKWARDS
> >  	select COMMON_CLK
> > -	select CPU_PM if CPU_IDLE || HIBERNATION
> > +	select CPU_PM if CPU_IDLE || HIBERNATION || SUSPEND
> >  	select EDAC_SUPPORT
> >  	select FRAME_POINTER if PERF_EVENTS || (FUNCTION_TRACER && !DYNAMIC_FTRACE)
> >  	select GENERIC_ARCH_TOPOLOGY
> > @@ -918,9 +918,13 @@ config PORTABLE
> >  	select MMU
> >  	select OF
> >  
> > +
> >  config ARCH_PROC_KCORE_TEXT
> >  	def_bool y
> >  
> > +config ARCH_SUSPEND_POSSIBLE
> > +	def_bool RISCV_SBI
> > +
> 
> This option was already added by commit c1f048a6bd7d ("riscv: Enable
> ARCH_SUSPEND_POSSIBLE for s2idle"), so this hunk is a duplicate.

Thanks, Samuel. I'll send a v3.

drew

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