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Subject[RESEND PATCH v2 3/3] powerpc/powernv: Parse device tree, population of SPR support
Date
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 <psampat@linux.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 d67d4d0b169b..e910ff40b7e6 100644
--- a/arch/powerpc/platforms/powernv/idle.c
+++ b/arch/powerpc/platforms/powernv/idle.c
@@ -1429,6 +1429,107 @@ 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 *np, *np1;
+ int rc = 0;
+
+ /* Self restore register population */
+ np = of_find_node_by_path("/ibm,opal/power-mgt/self-restore");
+ if (!np) {
+ pr_warn("opal: self restore Node not found");
+ } else {
+ rc = extract_save_restore_state_dt(np, SELF_RESTORE_TYPE);
+ if (rc != 0)
+ return rc;
+ }
+ /* Self save register population */
+ np1 = of_find_node_by_path("/ibm,opal/power-mgt/self-save");
+ if (!np1) {
+ pr_warn("opal: self save Node not found");
+ pr_warn("Legacy firmware. Assuming default self-restore support");
+ } else {
+ rc = extract_save_restore_state_dt(np1, 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
@@ -1577,6 +1678,9 @@ 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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