[PATCH RFC 07/27] PM / Domains: Read domain residency from DT

[Lina Iyer]

Domains that have expensive suspend resume operations, may require a
certain amount of time be spent in an idle state to reap the power
saving benefit. Such domains, may provide the residency requirement for
a domain state.

Read the residency for a domain state from the DT. A domain governor may
use this information in determining the state for the domain.

Cc: Axel Haslam <ahas...@baylibre.com>
Cc: Marc Titinger <mtitin...@baylibre.com>
Signed-off-by: Lina Iyer <lina.i...@linaro.org>
---
 Documentation/devicetree/bindings/power/power_domain.txt | 7 +++++++
 drivers/base/power/domain.c                              | 6 ++++++
 include/linux/pm_domain.h                                | 1 +
 3 files changed, 14 insertions(+)

diff --git a/Documentation/devicetree/bindings/power/power_domain.txt 
b/Documentation/devicetree/bindings/power/power_domain.txt
index ecfaf44..d71da29 100644
--- a/Documentation/devicetree/bindings/power/power_domain.txt
+++ b/Documentation/devicetree/bindings/power/power_domain.txt
@@ -67,6 +67,13 @@ have the following properties -
                If omitted, this is assumed to be equal to:
                        entry-latency-us + exit-latency-us
 
+       - residency-us:
+               Usage: Optional
+               Value type: <prop-encoded-array>
+               Definition: A u32 value representing the time for which a
+               domain must be idle in the state to reap power saving benefits
+               of entering the state.
+
        - state-param:
                Usage: Optional
                Value type: <prop-encoded-array>
diff --git a/drivers/base/power/domain.c b/drivers/base/power/domain.c
index 9a0df09..abc81bd 100644
--- a/drivers/base/power/domain.c
+++ b/drivers/base/power/domain.c
@@ -1245,6 +1245,7 @@ static int genpd_alloc_states_data(struct 
generic_pm_domain *genpd,
                        st[i].power_on_latency_ns;
                genpd->states[i].power_off_latency_ns =
                        st[i].power_off_latency_ns;
+               genpd->states[i].residency_ns = st[i].residency_ns;
                genpd->states[i].param = st[i].param;
        }
 
@@ -1513,6 +1514,7 @@ static int of_get_genpd_power_state(struct 
genpd_power_state *genpd_state,
        const struct of_device_id *match_id;
        int err = 0;
        u32 latency;
+       u32 residency;
        u32 param;
 
        match_id = of_match_node(power_state_match, state_node);
@@ -1554,6 +1556,10 @@ static int of_get_genpd_power_state(struct 
genpd_power_state *genpd_state,
                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;
diff --git a/include/linux/pm_domain.h b/include/linux/pm_domain.h
index 108a4b3..fed024a 100644
--- a/include/linux/pm_domain.h
+++ b/include/linux/pm_domain.h
@@ -41,6 +41,7 @@ struct genpd_power_state {
        char *name;
        s64 power_off_latency_ns;
        s64 power_on_latency_ns;
+       s64 residency_ns;
        u32 param;
 };
 
-- 
2.1.4

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