From: Axel Haslam <redacted>

This patch allows domains to define idle states in the DT. SoC's can
define domain idle states in DT using the "power-states" property of the
domain provider. Calling of_pm_genpd_init() will  read the idle states
and initialize the genpd for the domain.

In addition to the entry and exit latency for idle state, also add
residency and state-param properties. A domain idling in a state is only
power effecient if it stays idle for a certain period in that state. The
residency provides this minimum time for the idle state to provide power
benefits. The state-param is a state specific u32 value that the
platform may use for that idle state.

Signed-off-by: Marc Titinger <redacted>
Signed-off-by: Lina Iyer <redacted>
[Lina: Added state properties, removed state names, wakeup-latency,
added of_pm_genpd_init() API, pruned commit text]
Signed-off-by: Ulf Hansson <redacted>
[Ulf: Moved around code to make it compile properly, rebased on top of multiple
state support,changed to use pm_genpd_init()]
---
 drivers/base/power/domain.c | 84 ++++++++++++++++++++++++++++++++++++++++++++-
 include/linux/pm_domain.h   |  3 ++
 2 files changed, 86 insertions(+), 1 deletion(-)

diff --git a/drivers/base/power/domain.c b/drivers/base/power/domain.c
index a1f2aff..62ffabd 100644
--- a/drivers/base/power/domain.c
+++ b/drivers/base/power/domain.c

@@ -1253,6 +1253,82 @@ out:
 }
 EXPORT_SYMBOL_GPL(pm_genpd_remove_subdomain);
 
+static int genpd_of_get_power_state(struct genpd_power_state *genpd_state,
+				    struct device_node *state_node)
+{
+	int err = 0;
+	u32 latency;
+	u32 residency;
+	u32 param;
+	u32 entry_latency, exit_latency;
+
+	err = of_property_read_u32(state_node, "entry-latency-us",
+				   &entry_latency);
+	if (err) {
+		pr_debug(" * %s missing entry-latency-us property\n",
+			 state_node->full_name);
+		return -EINVAL;
+	}
+
+	err = of_property_read_u32(state_node, "exit-latency-us",
+				   &exit_latency);
+	if (err) {
+		pr_debug(" * %s missing exit-latency-us property\n",
+			 state_node->full_name);
+		return -EINVAL;
+	}
+
+	err = of_property_read_u32(state_node, "residency-us", &residency);
+	if (!err)
+		genpd_state->residency_ns = 1000 * residency;
+
+	err = of_property_read_u32(state_node, "state-param", &param);
+	if (!err)
+		genpd_state->param = param;
+
+	latency = entry_latency + exit_latency;
+	genpd_state->power_on_latency_ns = 1000 * latency;
+	genpd_state->power_off_latency_ns = 1000 * entry_latency;
+
+	return 0;
+}