[v4,13/14] cpuidle: psci: Add support for PM domains by using genpd

Message ID 20191211154343.29765-14-ulf.hansson@linaro.org
State Superseded
Headers show
Series
  • cpuidle: psci: Support hierarchical CPU arrangement
Related show

Commit Message

Ulf Hansson Dec. 11, 2019, 3:43 p.m.
When the hierarchical CPU topology layout is used in DT and the PSCI OSI
mode is supported by the PSCI FW, let's initialize a corresponding PM
domain topology by using genpd. This enables a CPU and a group of CPUs,
when attached to the topology, to be power-managed accordingly.

To trigger the attempt to initialize the genpd data structures let's use a
subsys_initcall, which should be early enough to allow CPUs, but also other
devices to be attached.

The initialization consists of parsing the PSCI OF node for the topology
and the "domain idle states" DT bindings. In case the idle states are
compatible with "domain-idle-state", the initialized genpd becomes
responsible of selecting an idle state for the PM domain, via assigning it
a genpd governor.

Note that, a successful initialization of the genpd data structures, is
followed by a call to psci_set_osi_mode(), as to try to enable the OSI mode
in the PSCI FW. In case this fails, we fall back into a degraded mode
rather than bailing out and returning an error code.

Co-developed-by: Lina Iyer <lina.iyer@linaro.org>
Signed-off-by: Lina Iyer <lina.iyer@linaro.org>

Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

---

Changes in v4:
	- None.

---
 drivers/cpuidle/cpuidle-psci-domain.c | 267 ++++++++++++++++++++++++++
 drivers/cpuidle/cpuidle-psci.c        |   4 +-
 drivers/cpuidle/cpuidle-psci.h        |   5 +
 3 files changed, 274 insertions(+), 2 deletions(-)

-- 
2.17.1

Comments

Ulf Hansson Dec. 19, 2019, 3:48 p.m. | #1
On Thu, 19 Dec 2019 at 15:34, Sudeep Holla <sudeep.holla@arm.com> wrote:
>

> On Wed, Dec 11, 2019 at 04:43:42PM +0100, Ulf Hansson wrote:

> > When the hierarchical CPU topology layout is used in DT and the PSCI OSI

> > mode is supported by the PSCI FW, let's initialize a corresponding PM

> > domain topology by using genpd. This enables a CPU and a group of CPUs,

> > when attached to the topology, to be power-managed accordingly.

> >

> > To trigger the attempt to initialize the genpd data structures let's use a

> > subsys_initcall, which should be early enough to allow CPUs, but also other

> > devices to be attached.

> >

> > The initialization consists of parsing the PSCI OF node for the topology

> > and the "domain idle states" DT bindings. In case the idle states are

> > compatible with "domain-idle-state", the initialized genpd becomes

> > responsible of selecting an idle state for the PM domain, via assigning it

> > a genpd governor.

> >

> > Note that, a successful initialization of the genpd data structures, is

> > followed by a call to psci_set_osi_mode(), as to try to enable the OSI mode

> > in the PSCI FW. In case this fails, we fall back into a degraded mode

> > rather than bailing out and returning an error code.

> >

> > Co-developed-by: Lina Iyer <lina.iyer@linaro.org>

> > Signed-off-by: Lina Iyer <lina.iyer@linaro.org>

> > Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

> > ---

> >

> > Changes in v4:

> >       - None.

> >

> > ---

> >  drivers/cpuidle/cpuidle-psci-domain.c | 267 ++++++++++++++++++++++++++

> >  drivers/cpuidle/cpuidle-psci.c        |   4 +-

> >  drivers/cpuidle/cpuidle-psci.h        |   5 +

> >  3 files changed, 274 insertions(+), 2 deletions(-)

> >

> > diff --git a/drivers/cpuidle/cpuidle-psci-domain.c b/drivers/cpuidle/cpuidle-psci-domain.c

> > index 656ef3d59149..c2f94ba42222 100644

> > --- a/drivers/cpuidle/cpuidle-psci-domain.c

> > +++ b/drivers/cpuidle/cpuidle-psci-domain.c

> > @@ -7,14 +7,281 @@

> >   *

> >   */

> >

> > +#define pr_fmt(fmt) "CPUidle PSCI: " fmt

> > +

> >  #include <linux/cpu.h>

> >  #include <linux/device.h>

> >  #include <linux/kernel.h>

> >  #include <linux/pm_domain.h>

> >  #include <linux/pm_runtime.h>

> > +#include <linux/psci.h>

> > +#include <linux/slab.h>

> > +#include <linux/string.h>

> >

> >  #include "cpuidle-psci.h"

> >

> > +struct psci_pd_provider {

> > +     struct list_head link;

> > +     struct device_node *node;

> > +};

> > +

> > +static LIST_HEAD(psci_pd_providers);

> > +static bool osi_mode_enabled;

> > +

> > +static int psci_pd_power_off(struct generic_pm_domain *pd)

> > +{

> > +     struct genpd_power_state *state = &pd->states[pd->state_idx];

> > +     u32 *pd_state;

> > +

> > +     /* If we have failed to enable OSI mode, then abort power off. */

> > +     if (!osi_mode_enabled)

> > +             return -EBUSY;

> > +

>

> Why is above check needed ? Shouldn't we have disable/remove pd of

> OSI is not enabled ?


Well, failing to enable OSI should in practice not happen, while it
theoretically it could.

My approach to this has been to fall back to use a "degraded mode",
which seems quite common for these kind of situations. The degraded
mode means, we are preventing domain states from being used.

More importantly, it also keeps the code registering the PM domains, a
bit simpler.

>

> > +     if (!state->data)

> > +             return 0;

> > +

> > +     /* OSI mode is enabled, set the corresponding domain state. */

> > +     pd_state = state->data;

> > +     psci_set_domain_state(*pd_state);

> > +

> > +     return 0;

> > +}

> > +

>

> [...]

>

> > +static const struct of_device_id psci_of_match[] __initconst = {

> > +     { .compatible = "arm,psci" },

>

> I think we can drop the above one as it's for v0.1 which didn't support

> OSI.


Yeah, I do that.

>

> > +     { .compatible = "arm,psci-0.2" },

> > +     { .compatible = "arm,psci-1.0" },

> > +     {}

> > +};

> > +

> > +static int __init psci_idle_init_domains(void)

> > +{

> > +     struct device_node *np = of_find_matching_node(NULL, psci_of_match);

> > +     struct device_node *node;

> > +     int ret = 0, pd_count = 0;

> > +

> > +     if (!np)

> > +             return -ENODEV;

> > +

> > +     /* Currently limit the hierarchical topology to be used in OSI mode. */

> > +     if (!psci_has_osi_support())

> > +             goto out;

> > +

> > +     /*

> > +      * Parse child nodes for the "#power-domain-cells" property and

> > +      * initialize a genpd/genpd-of-provider pair when it's found.

> > +      */

> > +     for_each_child_of_node(np, node) {

> > +             if (!of_find_property(node, "#power-domain-cells", NULL))

> > +                     continue;

> > +

> > +             ret = psci_pd_init(node);

> > +             if (ret)

> > +                     goto put_node;

> > +

> > +             pd_count++;

> > +     }

> > +

> > +     /* Bail out if not using the hierarchical CPU topology. */

> > +     if (!pd_count)

> > +             goto out;

> > +

> > +     /* Link genpd masters/subdomains to model the CPU topology. */

> > +     ret = psci_pd_init_topology(np);

> > +     if (ret)

> > +             goto remove_pd;

> > +

> > +     /* Try to enable OSI mode. */

> > +     ret = psci_set_osi_mode();

> > +     if (ret)

> > +             pr_warn("failed to enable OSI mode: %d\n", ret);

>

> Same question as above: shouldn't we disable and goto remove_pd ?


See my answer above. Does it satisfy your concern?

If so, may I add your reviewed-by tag, for the next re-spin when I
have removed one of the compatible strings?

Kind regards
Uffe

Patch

diff --git a/drivers/cpuidle/cpuidle-psci-domain.c b/drivers/cpuidle/cpuidle-psci-domain.c
index 656ef3d59149..c2f94ba42222 100644
--- a/drivers/cpuidle/cpuidle-psci-domain.c
+++ b/drivers/cpuidle/cpuidle-psci-domain.c
@@ -7,14 +7,281 @@ 
  *
  */
 
+#define pr_fmt(fmt) "CPUidle PSCI: " fmt
+
 #include <linux/cpu.h>
 #include <linux/device.h>
 #include <linux/kernel.h>
 #include <linux/pm_domain.h>
 #include <linux/pm_runtime.h>
+#include <linux/psci.h>
+#include <linux/slab.h>
+#include <linux/string.h>
 
 #include "cpuidle-psci.h"
 
+struct psci_pd_provider {
+	struct list_head link;
+	struct device_node *node;
+};
+
+static LIST_HEAD(psci_pd_providers);
+static bool osi_mode_enabled;
+
+static int psci_pd_power_off(struct generic_pm_domain *pd)
+{
+	struct genpd_power_state *state = &pd->states[pd->state_idx];
+	u32 *pd_state;
+
+	/* If we have failed to enable OSI mode, then abort power off. */
+	if (!osi_mode_enabled)
+		return -EBUSY;
+
+	if (!state->data)
+		return 0;
+
+	/* OSI mode is enabled, set the corresponding domain state. */
+	pd_state = state->data;
+	psci_set_domain_state(*pd_state);
+
+	return 0;
+}
+
+static int __init psci_pd_parse_state_nodes(struct genpd_power_state *states,
+					int state_count)
+{
+	int i, ret;
+	u32 psci_state, *psci_state_buf;
+
+	for (i = 0; i < state_count; i++) {
+		ret = psci_dt_parse_state_node(to_of_node(states[i].fwnode),
+					&psci_state);
+		if (ret)
+			goto free_state;
+
+		psci_state_buf = kmalloc(sizeof(u32), GFP_KERNEL);
+		if (!psci_state_buf) {
+			ret = -ENOMEM;
+			goto free_state;
+		}
+		*psci_state_buf = psci_state;
+		states[i].data = psci_state_buf;
+	}
+
+	return 0;
+
+free_state:
+	i--;
+	for (; i >= 0; i--)
+		kfree(states[i].data);
+	return ret;
+}
+
+static int __init psci_pd_parse_states(struct device_node *np,
+			struct genpd_power_state **states, int *state_count)
+{
+	int ret;
+
+	/* Parse the domain idle states. */
+	ret = of_genpd_parse_idle_states(np, states, state_count);
+	if (ret)
+		return ret;
+
+	/* Fill out the PSCI specifics for each found state. */
+	ret = psci_pd_parse_state_nodes(*states, *state_count);
+	if (ret)
+		kfree(*states);
+
+	return ret;
+}
+
+static void psci_pd_free_states(struct genpd_power_state *states,
+				unsigned int state_count)
+{
+	int i;
+
+	for (i = 0; i < state_count; i++)
+		kfree(states[i].data);
+	kfree(states);
+}
+
+static int __init psci_pd_init(struct device_node *np)
+{
+	struct generic_pm_domain *pd;
+	struct psci_pd_provider *pd_provider;
+	struct dev_power_governor *pd_gov;
+	struct genpd_power_state *states = NULL;
+	int ret = -ENOMEM, state_count = 0;
+
+	pd = kzalloc(sizeof(*pd), GFP_KERNEL);
+	if (!pd)
+		goto out;
+
+	pd_provider = kzalloc(sizeof(*pd_provider), GFP_KERNEL);
+	if (!pd_provider)
+		goto free_pd;
+
+	pd->name = kasprintf(GFP_KERNEL, "%pOF", np);
+	if (!pd->name)
+		goto free_pd_prov;
+
+	/*
+	 * Parse the domain idle states and let genpd manage the state selection
+	 * for those being compatible with "domain-idle-state".
+	 */
+	ret = psci_pd_parse_states(np, &states, &state_count);
+	if (ret)
+		goto free_name;
+
+	pd->free_states = psci_pd_free_states;
+	pd->name = kbasename(pd->name);
+	pd->power_off = psci_pd_power_off;
+	pd->states = states;
+	pd->state_count = state_count;
+	pd->flags |= GENPD_FLAG_IRQ_SAFE | GENPD_FLAG_CPU_DOMAIN;
+
+	/* Use governor for CPU PM domains if it has some states to manage. */
+	pd_gov = state_count > 0 ? &pm_domain_cpu_gov : NULL;
+
+	ret = pm_genpd_init(pd, pd_gov, false);
+	if (ret) {
+		psci_pd_free_states(states, state_count);
+		goto free_name;
+	}
+
+	ret = of_genpd_add_provider_simple(np, pd);
+	if (ret)
+		goto remove_pd;
+
+	pd_provider->node = of_node_get(np);
+	list_add(&pd_provider->link, &psci_pd_providers);
+
+	pr_debug("init PM domain %s\n", pd->name);
+	return 0;
+
+remove_pd:
+	pm_genpd_remove(pd);
+free_name:
+	kfree(pd->name);
+free_pd_prov:
+	kfree(pd_provider);
+free_pd:
+	kfree(pd);
+out:
+	pr_err("failed to init PM domain ret=%d %pOF\n", ret, np);
+	return ret;
+}
+
+static void __init psci_pd_remove(void)
+{
+	struct psci_pd_provider *pd_provider, *it;
+	struct generic_pm_domain *genpd;
+
+	list_for_each_entry_safe(pd_provider, it, &psci_pd_providers, link) {
+		of_genpd_del_provider(pd_provider->node);
+
+		genpd = of_genpd_remove_last(pd_provider->node);
+		if (!IS_ERR(genpd))
+			kfree(genpd);
+
+		of_node_put(pd_provider->node);
+		list_del(&pd_provider->link);
+		kfree(pd_provider);
+	}
+}
+
+static int __init psci_pd_init_topology(struct device_node *np)
+{
+	struct device_node *node;
+	struct of_phandle_args child, parent;
+	int ret;
+
+	for_each_child_of_node(np, node) {
+		if (of_parse_phandle_with_args(node, "power-domains",
+					"#power-domain-cells", 0, &parent))
+			continue;
+
+		child.np = node;
+		child.args_count = 0;
+
+		ret = of_genpd_add_subdomain(&parent, &child);
+		of_node_put(parent.np);
+		if (ret) {
+			of_node_put(node);
+			return ret;
+		}
+	}
+
+	return 0;
+}
+
+static const struct of_device_id psci_of_match[] __initconst = {
+	{ .compatible = "arm,psci" },
+	{ .compatible = "arm,psci-0.2" },
+	{ .compatible = "arm,psci-1.0" },
+	{}
+};
+
+static int __init psci_idle_init_domains(void)
+{
+	struct device_node *np = of_find_matching_node(NULL, psci_of_match);
+	struct device_node *node;
+	int ret = 0, pd_count = 0;
+
+	if (!np)
+		return -ENODEV;
+
+	/* Currently limit the hierarchical topology to be used in OSI mode. */
+	if (!psci_has_osi_support())
+		goto out;
+
+	/*
+	 * Parse child nodes for the "#power-domain-cells" property and
+	 * initialize a genpd/genpd-of-provider pair when it's found.
+	 */
+	for_each_child_of_node(np, node) {
+		if (!of_find_property(node, "#power-domain-cells", NULL))
+			continue;
+
+		ret = psci_pd_init(node);
+		if (ret)
+			goto put_node;
+
+		pd_count++;
+	}
+
+	/* Bail out if not using the hierarchical CPU topology. */
+	if (!pd_count)
+		goto out;
+
+	/* Link genpd masters/subdomains to model the CPU topology. */
+	ret = psci_pd_init_topology(np);
+	if (ret)
+		goto remove_pd;
+
+	/* Try to enable OSI mode. */
+	ret = psci_set_osi_mode();
+	if (ret)
+		pr_warn("failed to enable OSI mode: %d\n", ret);
+	else
+		osi_mode_enabled = true;
+
+	of_node_put(np);
+	pr_info("Initialized CPU PM domain topology\n");
+	return pd_count;
+
+put_node:
+	of_node_put(node);
+remove_pd:
+	if (pd_count)
+		psci_pd_remove();
+	pr_err("failed to create CPU PM domains ret=%d\n", ret);
+out:
+	of_node_put(np);
+	return ret;
+}
+subsys_initcall(psci_idle_init_domains);
+
 struct device *psci_dt_attach_cpu(int cpu)
 {
 	struct device *dev;
diff --git a/drivers/cpuidle/cpuidle-psci.c b/drivers/cpuidle/cpuidle-psci.c
index 34a89d99bb0f..70141090a298 100644
--- a/drivers/cpuidle/cpuidle-psci.c
+++ b/drivers/cpuidle/cpuidle-psci.c
@@ -34,7 +34,7 @@  static DEFINE_PER_CPU_READ_MOSTLY(struct psci_cpuidle_data, psci_cpuidle_data);
 static DEFINE_PER_CPU(u32, domain_state);
 static bool psci_cpuidle_use_cpuhp;
 
-static inline void psci_set_domain_state(u32 state)
+void psci_set_domain_state(u32 state)
 {
 	__this_cpu_write(domain_state, state);
 }
@@ -143,7 +143,7 @@  static const struct of_device_id psci_idle_state_match[] __initconst = {
 	{ },
 };
 
-static int __init psci_dt_parse_state_node(struct device_node *np, u32 *state)
+int __init psci_dt_parse_state_node(struct device_node *np, u32 *state)
 {
 	int err = of_property_read_u32(np, "arm,psci-suspend-param", state);
 
diff --git a/drivers/cpuidle/cpuidle-psci.h b/drivers/cpuidle/cpuidle-psci.h
index 0cadbb71dc55..d2e55cad9ac6 100644
--- a/drivers/cpuidle/cpuidle-psci.h
+++ b/drivers/cpuidle/cpuidle-psci.h
@@ -3,6 +3,11 @@ 
 #ifndef __CPUIDLE_PSCI_H
 #define __CPUIDLE_PSCI_H
 
+struct device_node;
+
+void psci_set_domain_state(u32 state);
+int __init psci_dt_parse_state_node(struct device_node *np, u32 *state);
+
 #ifdef CONFIG_PM_GENERIC_DOMAINS_OF
 struct device *psci_dt_attach_cpu(int cpu);
 #else