[PATCH v2 4/5] drivers: firmware: psci: add extended stateid power_state support

[Kevin Hilman]

On Wed, Jul 8, 2015 at 10:16 AM, Lorenzo Pieralisi
<lorenzo.pieralisi at arm.com> wrote:
> PSCI v1.0 augmented the power_state parameter format specification
> (extended stateid) and introduced a way to probe it through the
> PSCI_FEATURES interface.
>
> This patch implements code that detects the power_state format at
> run-time through the PSCI_FEATURES interface, so that the power_state
> argument can be properly detected and validated in the kernel according
> to the information provided through firmware.
>
> Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi at arm.com>
> Cc: Mark Rutland <mark.rutland at arm.com>

kernelci.org started finding a new boot failures in the arm-soc tree
on arm64 qemu[1] and it was bisected down to this patch, which is in
arm-soc in the form of commit a5c00bb28da0 (drivers: firmware: psci:
add extended stateid power_state support)

The patch doesn't revert cleanly, so I didn't dig much further, but
this suggests that some more testing on qemu is needed (or does qemu
need to be upgraded?)

Kevin

[1] http://kernelci.org/boot/all/job/arm-soc/kernel/v4.3-rc5-557-g159ca7e43189/

> ---
>  drivers/firmware/psci.c   | 34 ++++++++++++++++++++++++++++++++--
>  include/uapi/linux/psci.h | 12 ++++++++++++
>  2 files changed, 44 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/firmware/psci.c b/drivers/firmware/psci.c
> index 24ef3a8..bd2ba5b 100644
> --- a/drivers/firmware/psci.c
> +++ b/drivers/firmware/psci.c
> @@ -75,14 +75,34 @@ static u32 psci_function_id[PSCI_FN_MAX];
>                                 PSCI_0_2_POWER_STATE_TYPE_MASK | \
>                                 PSCI_0_2_POWER_STATE_AFFL_MASK)
>
> +#define PSCI_1_0_EXT_POWER_STATE_MASK          \
> +                               (PSCI_1_0_EXT_POWER_STATE_ID_MASK | \
> +                               PSCI_1_0_EXT_POWER_STATE_TYPE_MASK)
> +
> +static u32 psci_cpu_suspend_feature;
> +
> +static inline bool psci_has_ext_power_state(void)
> +{
> +       return psci_cpu_suspend_feature &
> +                               PSCI_1_0_FEATURES_CPU_SUSPEND_PF_MASK;
> +}
> +
>  bool psci_power_state_loses_context(u32 state)
>  {
> -       return state & PSCI_0_2_POWER_STATE_TYPE_MASK;
> +       const u32 mask = psci_has_ext_power_state() ?
> +                                       PSCI_1_0_EXT_POWER_STATE_TYPE_MASK :
> +                                       PSCI_0_2_POWER_STATE_TYPE_MASK;
> +
> +       return state & mask;
>  }
>
>  bool psci_power_state_is_valid(u32 state)
>  {
> -       return !(state & ~PSCI_0_2_POWER_STATE_MASK);
> +       const u32 valid_mask = psci_has_ext_power_state() ?
> +                              PSCI_1_0_EXT_POWER_STATE_MASK :
> +                              PSCI_0_2_POWER_STATE_MASK;
> +
> +       return !(state & ~valid_mask);
>  }
>
>  static int psci_to_linux_errno(int errno)
> @@ -203,6 +223,14 @@ static int __init psci_features(u32 psci_func_id)
>                               psci_func_id, 0, 0);
>  }
>
> +static void __init psci_init_cpu_suspend(void)
> +{
> +       int feature = psci_features(psci_function_id[PSCI_FN_CPU_SUSPEND]);
> +
> +       if (feature != PSCI_RET_NOT_SUPPORTED)
> +               psci_cpu_suspend_feature = feature;
> +}
> +
>  /*
>   * Detect the presence of a resident Trusted OS which may cause CPU_OFF to
>   * return DENIED (which would be fatal).
> @@ -287,6 +315,8 @@ static int __init psci_probe(void)
>
>         psci_init_migrate();
>
> +       psci_init_cpu_suspend();
> +
>         return 0;
>  }
>
> diff --git a/include/uapi/linux/psci.h b/include/uapi/linux/psci.h
> index 187b828d..0a9485f 100644
> --- a/include/uapi/linux/psci.h
> +++ b/include/uapi/linux/psci.h
> @@ -58,6 +58,13 @@
>  #define PSCI_0_2_POWER_STATE_AFFL_MASK         \
>                                 (0x3 << PSCI_0_2_POWER_STATE_AFFL_SHIFT)
>
> +/* PSCI extended power state encoding for CPU_SUSPEND function */
> +#define PSCI_1_0_EXT_POWER_STATE_ID_MASK       0xfffffff
> +#define PSCI_1_0_EXT_POWER_STATE_ID_SHIFT      0
> +#define PSCI_1_0_EXT_POWER_STATE_TYPE_SHIFT    30
> +#define PSCI_1_0_EXT_POWER_STATE_TYPE_MASK     \
> +                               (0x1 << PSCI_1_0_EXT_POWER_STATE_TYPE_SHIFT)
> +
>  /* PSCI v0.2 affinity level state returned by AFFINITY_INFO */
>  #define PSCI_0_2_AFFINITY_LEVEL_ON             0
>  #define PSCI_0_2_AFFINITY_LEVEL_OFF            1
> @@ -78,6 +85,11 @@
>  #define PSCI_VERSION_MINOR(ver)                        \
>                 ((ver) & PSCI_VERSION_MINOR_MASK)
>
> +/* PSCI features decoding (>=1.0) */
> +#define PSCI_1_0_FEATURES_CPU_SUSPEND_PF_SHIFT 1
> +#define PSCI_1_0_FEATURES_CPU_SUSPEND_PF_MASK  \
> +                       (0x1 << PSCI_1_0_FEATURES_CPU_SUSPEND_PF_SHIFT)
> +
>  /* PSCI return values (inclusive of all PSCI versions) */
>  #define PSCI_RET_SUCCESS                       0
>  #define PSCI_RET_NOT_SUPPORTED                 -1
> --
> 2.2.1
>