Parse the device tree for nodes self-save, self-restore and populate
support for the preferred SPRs based what was advertised by the device
tree.

Signed-off-by: Pratik Rajesh Sampat <psam...@linux.ibm.com>
Reviewed-by: Ram Pai <linux...@us.ibm.com>
---
 arch/powerpc/platforms/powernv/idle.c | 104 ++++++++++++++++++++++++++
 1 file changed, 104 insertions(+)

diff --git a/arch/powerpc/platforms/powernv/idle.c 
b/arch/powerpc/platforms/powernv/idle.c
index 97aeb45e897b..384980c743eb 100644
--- a/arch/powerpc/platforms/powernv/idle.c
+++ b/arch/powerpc/platforms/powernv/idle.c
@@ -1436,6 +1436,107 @@ static void __init pnv_probe_idle_states(void)
                supported_cpuidle_states |= pnv_idle_states[i].flags;
 }
 
+/*
+ * Extracts and populates the self save or restore capabilities
+ * passed from the device tree node
+ */
+static int extract_save_restore_state_dt(struct device_node *np, int type)
+{
+       int nr_sprns = 0, i, bitmask_index;
+       int rc = 0;
+       u64 *temp_u64;
+       const char *state_prop;
+       u64 bit_pos;
+
+       state_prop = of_get_property(np, "status", NULL);
+       if (!state_prop) {
+               pr_warn("opal: failed to find the active value for self 
save/restore node");
+               return -EINVAL;
+       }
+       if (strncmp(state_prop, "disabled", 8) == 0) {
+               /*
+                * if the feature is not active, strip the preferred_sprs from
+                * that capability.
+                */
+               if (type == SELF_RESTORE_TYPE) {
+                       for (i = 0; i < nr_preferred_sprs; i++) {
+                               preferred_sprs[i].supported_mode &=
+                                       ~SELF_RESTORE_STRICT;
+                       }
+               } else {
+                       for (i = 0; i < nr_preferred_sprs; i++) {
+                               preferred_sprs[i].supported_mode &=
+                                       ~SELF_SAVE_STRICT;
+                       }
+               }
+               return 0;
+       }
+       nr_sprns = of_property_count_u64_elems(np, "sprn-bitmask");
+       if (nr_sprns <= 0)
+               return rc;
+       temp_u64 = kcalloc(nr_sprns, sizeof(u64), GFP_KERNEL);
+       if (of_property_read_u64_array(np, "sprn-bitmask",
+                                      temp_u64, nr_sprns)) {
+               pr_warn("cpuidle-powernv: failed to find registers in DT\n");
+               kfree(temp_u64);
+               return -EINVAL;
+       }
+       /*
+        * Populate acknowledgment of support for the sprs in the global vector
+        * gotten by the registers supplied by the firmware.
+        * The registers are in a bitmask, bit index within
+        * that specifies the SPR
+        */
+       for (i = 0; i < nr_preferred_sprs; i++) {
+               bitmask_index = preferred_sprs[i].spr / 64;
+               bit_pos = preferred_sprs[i].spr % 64;
+               if ((temp_u64[bitmask_index] & (1UL << bit_pos)) == 0) {
+                       if (type == SELF_RESTORE_TYPE)
+                               preferred_sprs[i].supported_mode &=
+                                       ~SELF_RESTORE_STRICT;
+                       else
+                               preferred_sprs[i].supported_mode &=
+                                       ~SELF_SAVE_STRICT;
+                       continue;
+               }
+               if (type == SELF_RESTORE_TYPE) {
+                       preferred_sprs[i].supported_mode |=
+                               SELF_RESTORE_STRICT;
+               } else {
+                       preferred_sprs[i].supported_mode |=
+                               SELF_SAVE_STRICT;
+               }
+       }
+
+       kfree(temp_u64);
+       return rc;
+}
+
+static int pnv_parse_deepstate_dt(void)
+{
+       struct device_node *sr_np, *ss_np;
+       int rc = 0;
+
+       /* Self restore register population */
+       sr_np = of_find_node_by_path("/ibm,opal/power-mgt/self-restore");
+       if (!sr_np) {
+               pr_warn("opal: self restore Node not found");
+       } else {
+               rc = extract_save_restore_state_dt(sr_np, SELF_RESTORE_TYPE);
+               if (rc != 0)
+                       return rc;
+       }
+       /* Self save register population */
+       ss_np = of_find_node_by_path("/ibm,opal/power-mgt/self-save");
+       if (!ss_np) {
+               pr_warn("opal: self save Node not found");
+               pr_warn("Legacy firmware. Assuming default self-restore 
support");
+       } else {
+               rc = extract_save_restore_state_dt(ss_np, SELF_SAVE_TYPE);
+       }
+       return rc;
+}
+
 /*
  * This function parses device-tree and populates all the information
  * into pnv_idle_states structure. It also sets up nr_pnv_idle_states
@@ -1584,6 +1685,9 @@ static int __init pnv_init_idle_states(void)
                return rc;
        pnv_probe_idle_states();
 
+       rc = pnv_parse_deepstate_dt();
+       if (rc)
+               return rc;
        if (!cpu_has_feature(CPU_FTR_ARCH_300)) {
                if (!(supported_cpuidle_states & OPAL_PM_SLEEP_ENABLED_ER1)) {
                        power7_fastsleep_workaround_entry = false;
-- 
2.24.1

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