[PATCH v2 3/3] drivers: firmware: psci: add system suspend support

[Jisheng Zhang]

Hi Sudeep,

I'm sorry to being late. Just have some comments below.

On Thu, 18 Jun 2015 15:41:34 +0100
Sudeep Holla <sudeep.holla at arm.com> wrote:

> PSCI v1.0 introduces a new API called PSCI_SYSTEM_SUSPEND. This API
> provides the mechanism by which the calling OS can request entry into
> the deepest possible system sleep state.
> 
> It meets all the necessary preconditions for entering suspend to RAM
> state in Linux. This patch adds support for PSCI_SYSTEM_SUSPEND in psci
> firmware and registers a psci system suspend operation to implement the
> suspend-to-RAM(s2r) in a generic way on all the platforms implementing
> PSCI.
> 
> Cc: Mark Rutland <mark.rutland at arm.com>
> Cc: Lorenzo Pieralisi <lorenzo.pieralisi at arm.com>
> Signed-off-by: Sudeep Holla <sudeep.holla at arm.com>
> ---
>  drivers/firmware/psci.c   | 31 +++++++++++++++++++++++++++++++
>  include/uapi/linux/psci.h |  3 +++
>  2 files changed, 34 insertions(+)
> 
> diff --git a/drivers/firmware/psci.c b/drivers/firmware/psci.c
> index 752ca7c9eb97..f2b2b3e1c6e4 100644
> --- a/drivers/firmware/psci.c
> +++ b/drivers/firmware/psci.c
> @@ -20,11 +20,13 @@
>  #include <linux/printk.h>
>  #include <linux/psci.h>
>  #include <linux/reboot.h>
> +#include <linux/suspend.h>
>  
>  #include <uapi/linux/psci.h>
>  
>  #include <asm/system_misc.h>
>  #include <asm/smp_plat.h>
> +#include <asm/suspend.h>
>  
>  /*
>   * While a 64-bit OS can make calls with SMC32 calling conventions, for some
> @@ -222,6 +224,33 @@ static int __init psci_features(u32 psci_func_id)
>  			      psci_func_id, 0, 0);
>  }
>  
> +static int psci_system_suspend(unsigned long unused)
> +{
> +	return invoke_psci_fn(PSCI_FN_NATIVE(1_0, SYSTEM_SUSPEND),
> +			      virt_to_phys(cpu_resume), 0, 0);
> +}
> +
> +static int psci_system_suspend_enter(suspend_state_t state)
> +{
> +	return cpu_suspend(0, psci_system_suspend);
> +}
> +
> +static const struct platform_suspend_ops psci_suspend_ops = {
> +	.valid          = suspend_valid_only_mem,
> +	.enter          = psci_system_suspend_enter,
> +};
> +
> +static void __init psci_init_system_suspend(void)
> +{
> +	if (!IS_ENABLED(CONFIG_SUSPEND))
> +		return;
> +
> +	if (psci_features(PSCI_FN_NATIVE(1_0, SYSTEM_SUSPEND)))
> +		return;

So this requires the firmware implements SYSTEM_SUSPEND which doesn't exist
until PSCI 1.0, and even in PSCI 1.0 SYSTEM_SUSPEND is optional, we also want
suspend to ram feature on PSCI 0.2 or PSCI 1.0 w/o SYSTEM_SUSPEND, is there
any possibility to bring your previous RFC patch[1] back? Or ARM expect all
PSCI users must have SYSTEM_SUSPEND implemented if they want s2ram?

[1] http://lists.infradead.org/pipermail/linux-arm-kernel/2015-January/318541.html

Thank you,
Jisheng

> +
> +	suspend_set_ops(&psci_suspend_ops);
> +}
> +
>  static void __init psci_init_cpu_suspend(void)
>  {
>  	int feature = psci_features(psci_function_id[PSCI_FN_CPU_SUSPEND]);
> @@ -311,6 +340,8 @@ static int __init psci_probe(void)
>  
>  	psci_init_cpu_suspend();
>  
> +	psci_init_system_suspend();
> +
>  	return 0;
>  }
>  
> diff --git a/include/uapi/linux/psci.h b/include/uapi/linux/psci.h
> index 2598d7c9bf20..a1a2d85a91b9 100644
> --- a/include/uapi/linux/psci.h
> +++ b/include/uapi/linux/psci.h
> @@ -47,6 +47,9 @@
>  #define PSCI_0_2_FN64_MIGRATE_INFO_UP_CPU	PSCI_0_2_FN64(7)
>  
>  #define PSCI_1_0_FN_PSCI_FEATURES		PSCI_0_2_FN(10)
> +#define PSCI_1_0_FN_SYSTEM_SUSPEND		PSCI_0_2_FN(14)
> +
> +#define PSCI_1_0_FN64_SYSTEM_SUSPEND		PSCI_0_2_FN64(14)
>  
>  /* PSCI v0.2 power state encoding for CPU_SUSPEND function */
>  #define PSCI_0_2_POWER_STATE_ID_MASK		0xffff