[PATCH v1 1/2] PSCI: Use DT Function ID values only for old versions of spec
Mark Rutland
mark.rutland at arm.com
Thu Mar 20 10:57:42 EDT 2014
On Thu, Mar 20, 2014 at 12:54:24AM +0000, Ashwin Chaugule wrote:
> The PSCI v0.2+ spec mandates specific values of Function IDs
> for ARM32 and ARM64. Use DT bindings of Function IDs only
> when using older versions. Use static values otherwise.
> This patch also prepares the code to easily use the ACPI API
> which is based off of PSCI v0.2+.
>
> Signed-off-by: Ashwin Chaugule <ashwin.chaugule at linaro.org>
> ---
> arch/arm/include/asm/psci.h | 15 ++++++
> arch/arm/kernel/psci.c | 110 +++++++++++++++++++++++++++++++++++++-----
> arch/arm64/include/asm/psci.h | 12 +++++
> arch/arm64/kernel/psci.c | 106 +++++++++++++++++++++++++++++++++++-----
> 4 files changed, 218 insertions(+), 25 deletions(-)
>
> diff --git a/arch/arm/include/asm/psci.h b/arch/arm/include/asm/psci.h
> index c4ae171..3f8ebf9 100644
> --- a/arch/arm/include/asm/psci.h
> +++ b/arch/arm/include/asm/psci.h
> @@ -17,6 +17,19 @@
> #define PSCI_POWER_STATE_TYPE_STANDBY 0
> #define PSCI_POWER_STATE_TYPE_POWER_DOWN 1
>
> +/* PSCI Function ID's for ARM32 as per PSCI spec v0.2 */
Please drop the superfluous apostrophes, we aren't greengrocers [1].
%s/ID's/IDs/
> +
> +#define PSCI_ID_VERSION 0x84000000
> +#define PSCI_ID_CPU_SUSPEND 0x84000001
> +#define PSCI_ID_CPU_OFF 0x84000002
> +#define PSCI_ID_CPU_ON 0x84000003
> +#define PSCI_ID_AFFINITY_INFO 0x84000004
> +#define PSCI_ID_CPU_MIGRATE 0x84000005
> +#define PSCI_ID_MIGRATE_INFO_TYPE 0x84000006
> +#define PSCI_ID_MIGRATE_INFO_UP_CPU 0x84000007
> +#define PSCI_ID_SYSTEM_OFF 0x84000008
> +#define PSCI_ID_SYSTEM_RESET 0x84000009
> +
> struct psci_power_state {
> u16 id;
> u8 type;
> @@ -36,9 +49,11 @@ extern struct smp_operations psci_smp_ops;
>
> #ifdef CONFIG_ARM_PSCI
> void psci_init(void);
> +int psci_get_version(void);
> bool psci_smp_available(void);
> #else
> static inline void psci_init(void) { }
> +static inline int psci_get_version(void) { }
> static inline bool psci_smp_available(void) { return false; }
> #endif
>
> diff --git a/arch/arm/kernel/psci.c b/arch/arm/kernel/psci.c
> index 4693188..48e0b0a 100644
> --- a/arch/arm/kernel/psci.c
> +++ b/arch/arm/kernel/psci.c
> @@ -27,6 +27,7 @@
> struct psci_operations psci_ops;
>
> static int (*invoke_psci_fn)(u32, u32, u32, u32);
> +typedef int (*psci_initcall_t)(const struct device_node *);
>
> enum psci_function {
> PSCI_FN_CPU_SUSPEND,
> @@ -110,6 +111,20 @@ static noinline int __invoke_psci_fn_smc(u32 function_id, u32 arg0, u32 arg1,
> return function_id;
> }
>
> +#define PSCI_VER_MAJOR_MASK 0xffff0000
> +#define PSCI_VER_MINOR_MASK 0x0000ffff
> +#define PSCI_VER_MAJOR_SHIFT 16
> +
> +static int psci_get_version(void)
> +{
> + int err;
> + u32 fn;
> +
> + fn = PSCI_ID_VERSION;
> + err = invoke_psci_fn(fn, 0, 0, 0);
Do we need fn here? Can't we pass PSCI_ID_VERSION directly?
> + return err;
> +}
> +
> static int psci_cpu_suspend(struct psci_power_state state,
> unsigned long entry_point)
> {
> @@ -153,25 +168,65 @@ static int psci_migrate(unsigned long cpuid)
> return psci_to_linux_errno(err);
> }
>
> -static const struct of_device_id psci_of_match[] __initconst = {
> - { .compatible = "arm,psci", },
> - {},
> -};
> +/*
> + * PSCI Function ID's for v0.2+ are well defined so use
> + * static values.
> + */
> +static int psci_static_init(struct device_node *np)
> +{
> + const char *method;
> + int err = 0;
> +
> + pr_info("probing for conduit method from DT.\n");
> +
> + if (of_property_read_string(np, "method", &method)) {
> + pr_warn("missing \"method\" property\n");
> + err = -ENXIO;
> + goto out_put_node;
> + }
> +
> + if (!strcmp("hvc", method)) {
> + invoke_psci_fn = __invoke_psci_fn_hvc;
> + } else if (!strcmp("smc", method)) {
> + invoke_psci_fn = __invoke_psci_fn_smc;
> + } else {
> + pr_warn("invalid \"method\" property: %s\n", method);
> + err = -EINVAL;
> + goto out_put_node;
> + }
>
> -void __init psci_init(void)
> + pr_info("Using static PSCIv0.2+ function IDs\n");
How about "Using standard PSCI 0.2 function IDs"?
We're not using anything beyond PSCI 0.2 (yet), and "static" implies
that there are dynamic IDs also.
> + psci_function_id[PSCI_FN_CPU_SUSPEND] = PSCI_ID_CPU_SUSPEND;
> + psci_ops.cpu_suspend = psci_cpu_suspend;
> +
> + psci_function_id[PSCI_FN_CPU_OFF] = PSCI_ID_CPU_OFF;
> + psci_ops.cpu_off = psci_cpu_off;
> +
> + psci_function_id[PSCI_FN_CPU_ON] = PSCI_ID_CPU_ON;
> + psci_ops.cpu_on = psci_cpu_on;
> +
> + psci_function_id[PSCI_FN_MIGRATE] = PSCI_ID_CPU_MIGRATE;
> + psci_ops.migrate = psci_migrate;
> +
> +out_put_node:
> + of_node_put(np);
> + return err;
> +}
I'd very much like to see us use AFFINITY_INFO from the start, or we've
got a racy down path (as we have for all PSCI implementations prior to
0.2), and implementors are likely to skip implementing it if Linux seems
to work, so we'll never be able to rely on it.
Additionally it'd be nice to check what MIGRATE_INFO_TYPE returns. If it
returns a value other than 2 (MP or not present), then there's some
additional work that we need to perform around a down path or we might
not be able to shut down some CPUs.
> +
> +/*
> + * PSCI < v0.2 can override PSCI function ID's via DT.
> + */
> +static int psci_of_init(struct device_node *np)
> {
> - struct device_node *np;
> const char *method;
> u32 id;
> -
> - np = of_find_matching_node(NULL, psci_of_match);
> - if (!np)
> - return;
> + int err = 0;
>
> pr_info("probing function IDs from device-tree\n");
>
> if (of_property_read_string(np, "method", &method)) {
> - pr_warning("missing \"method\" property\n");
> + pr_warn("missing \"method\" property\n");
> + err = -EINVAL;
> goto out_put_node;
> }
>
> @@ -180,7 +235,8 @@ void __init psci_init(void)
> } else if (!strcmp("smc", method)) {
> invoke_psci_fn = __invoke_psci_fn_smc;
> } else {
> - pr_warning("invalid \"method\" property: %s\n", method);
> + pr_warn("invalid \"method\" property: %s\n", method);
> + err = -ENXIO;
> goto out_put_node;
> }
We should definitely factor this into a helper rather than duplicating
it.
>
> @@ -206,5 +262,33 @@ void __init psci_init(void)
>
> out_put_node:
> of_node_put(np);
> - return;
> + return err;
> +}
> +
> +static const struct of_device_id psci_of_match[] __initconst = {
> + { .compatible = "arm,psci", .data = psci_of_init},
> + { .compatible = "arm,psci-0.2", .data = psci_static_init},
> + {},
> +};
> +
> +int __init psci_init(void)
> +{
> + struct device_node *np;
> + const struct of_device_id *matched_np;
> + psci_initcall_t init_fn;
> + int ver = 0;
> +
> + np = of_find_matching_node_and_match(NULL, psci_of_match, &matched_np);
> + if (!np)
> + return -ENODEV;
> +
> + ver = psci_get_version();
> +
> + pr_info("using static PSCIv%d.%d Function IDs\n",
> + (ver & PSCI_VER_MAJOR_MASK) >> PSCI_VER_MAJOR_SHIFT,
> + (ver & PSCI_VER_MINOR_MASK));
Thanks for adding the version information.
Cheers,
Mark.
[1] http://en.wikipedia.org/wiki/Apostrophe#Superfluous_apostrophes_.28.22greengrocers.27_apostrophes.22.29
More information about the linux-arm-kernel
mailing list