PSCI v0.2 support and DT bindings

The PSCIv0.2 spec defines standard values of function IDs and introduces a few new functions. Detect version of PSCI and appropriately select the right PSCI functions.

Signed-off-by Ashwin Chaugule <[email protected]>

---
 arch/arm/include/asm/psci.h |   7 +-
 arch/arm/kernel/psci.c      | 155 ++++++++++++++++++++++++++++++++++--------
 arch/arm64/kernel/psci.c    | 160 +++++++++++++++++++++++++++++++++++---------
 include/uapi/linux/psci.h   |  61 +++++++++++++++++
 4 files changed, 323 insertions(+), 60 deletions(-)
 create mode 100644 include/uapi/linux/psci.h

arch/arm/include/asm/psci.h +5 -2

index c4ae171..b93e34a 100644
@@ -29,16 +29,19 @@ struct psci_operations {
        int (*cpu_off)(struct psci_power_state state);
        int (*cpu_on)(unsigned long cpuid, unsigned long entry_point);
        int (*migrate)(unsigned long cpuid);
+       int (*affinity_info)(unsigned long target_affinity,
+                       unsigned long lowest_affinity_level);
+       int (*migrate_info_type)(void);
 };
 
 extern struct psci_operations psci_ops;
 extern struct smp_operations psci_smp_ops;
 
 #ifdef CONFIG_ARM_PSCI
-void psci_init(void);
+int psci_init(void);
 bool psci_smp_available(void);
 #else
-static inline void psci_init(void) { }
+static inline int psci_init(void) { }
 static inline bool psci_smp_available(void) { return false; }
 #endif
 

arch/arm/kernel/psci.c +49 -27

index 4693188..46b23b6 100644
@@ -17,6 +17,7 @@
 
 #include <linux/init.h>
 #include <linux/of.h>
+#include <uapi/linux/psci.h>
 
 #include <asm/compiler.h>
 #include <asm/errno.h>

@@ -27,22 +28,20 @@
 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,
        PSCI_FN_CPU_ON,
        PSCI_FN_CPU_OFF,
        PSCI_FN_MIGRATE,
+       PSCI_FN_AFFINITY_INFO,
+       PSCI_FN_MIGRATE_INFO_TYPE,
        PSCI_FN_MAX,
 };
 
 static u32 psci_function_id[PSCI_FN_MAX];
 
-#define PSCI_RET_SUCCESS               0
-#define PSCI_RET_EOPNOTSUPP            -1
-#define PSCI_RET_EINVAL                        -2
-#define PSCI_RET_EPERM                 -3
-
 static int psci_to_linux_errno(int errno)
 {
        switch (errno) {

@@ -59,13 +58,6 @@ static int psci_to_linux_errno(int errno)
        return -EINVAL;
 }
 
-#define PSCI_POWER_STATE_ID_MASK       0xffff
-#define PSCI_POWER_STATE_ID_SHIFT      0
-#define PSCI_POWER_STATE_TYPE_MASK     0x1
-#define PSCI_POWER_STATE_TYPE_SHIFT    16
-#define PSCI_POWER_STATE_AFFL_MASK     0x3
-#define PSCI_POWER_STATE_AFFL_SHIFT    24
-
 static u32 psci_power_state_pack(struct psci_power_state state)
 {
        return  ((state.id & PSCI_POWER_STATE_ID_MASK)

@@ -110,6 +102,14 @@ static noinline int __invoke_psci_fn_smc(u32 function_id, u32 arg0, u32 arg1,
        return function_id;
 }
 
+static int psci_get_version(void)
+{
+       int err;
+
+       err = invoke_psci_fn(PSCI_ID_VERSION, 0, 0, 0);
+       return err;
+}
+
 static int psci_cpu_suspend(struct psci_power_state state,
                            unsigned long entry_point)
 {

@@ -153,26 +153,36 @@ 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",     },
-       {},
-};
+static int psci_affinity_info(unsigned long target_affinity,
+               unsigned long lowest_affinity_level)
+{
+       int err;
+       u32 fn;
 
-void __init psci_init(void)
+       fn = psci_function_id[PSCI_FN_AFFINITY_INFO];
+       err = invoke_psci_fn(fn, target_affinity, lowest_affinity_level, 0);
+       return err;
+}
+
+static int psci_migrate_info_type(void)
 {
-       struct device_node *np;
-       const char *method;
-       u32 id;
+       int err;
+       u32 fn;
 
-       np = of_find_matching_node(NULL, psci_of_match);
-       if (!np)
-               return;
+       fn = psci_function_id[PSCI_FN_MIGRATE_INFO_TYPE];
+       err = invoke_psci_fn(fn, 0, 0, 0);
+       return err;
+}
 
-       pr_info("probing function IDs from device-tree\n");
+static int get_set_conduit_method(struct device_node *np)
+{
+       const char *method;
+
+       pr_info("probing for conduit method from DT.\n");
 
        if (of_property_read_string(np, "method", &method)) {
-               pr_warning("missing \"method\" property\n");
-               goto out_put_node;
+               pr_warn("missing \"method\" property\n");
+               return -ENXIO;
        }
 
        if (!strcmp("hvc", method)) {

@@ -180,10 +190,79 @@ 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);
+               return -EINVAL;
+       }
+       return 0;
+}
+
+/*
+ * PSCI Function IDs for v0.2+ are well defined so use
+ * standard values.
+ */
+static int psci_0_2_init(struct device_node *np)
+{
+       int err, ver;

Review

Quoted 2 lines

(quoted diff) +2 -0

+       if (ver == PSCI_RET_EOPNOTSUPP) {
+               pr_info("PSCI_ID_VERSION Function not supported in firmware.\n");

IMO you should stop here as the implementation conforming to the specification must return a minor version number of 2 and major version number of 0. You can't proceed, assume ids and use them.

Hi Sudeep,

Quoted 3 lines · Sudeep Holla

Quoted 2 lines

(quoted diff) +2 -0

+       if (ver == PSCI_RET_EOPNOTSUPP) {
+               pr_info("PSCI_ID_VERSION Function not supported in firmware.\n");

Quoted 4 lines

IMO you should stop here as the implementation conforming to the specification must return a minor version number of 2 and major version number of 0. You can't proceed, assume ids and use them.

hm, you're right, I missed that.

Cheers,
Ashwin

Quoted 7 lines · Ashwin Chaugule

Hi Sudeep,

Quoted 3 lines · Sudeep Holla

Quoted 2 lines

(quoted diff) +2 -0

+       if (ver == PSCI_RET_EOPNOTSUPP) {
+               pr_info("PSCI_ID_VERSION Function not supported in firmware.\n");

Quoted 6 lines

Quoted 4 lines

IMO you should stop here as the implementation conforming to the specification must return a minor version number of 2 and major version number of 0. You can't proceed, assume ids and use them.

hm, you're right, I missed that.

Something like this?

if (ver == PSCI_RET_EOPNOTSUPP) {
         /* PSCI v0.2+ mandates implementation of PSCI_ID_VERSION. */
         pr_err("PSCI firmware does not comply with the v0.2 spec.\n");
         err = -EOPNOTSUPP;
         goto out_put_node;