diff mbox series

[RFC,v4,5/8] cpuidle: Factor-out power domain related code from PSCI domain driver

Message ID 20210517130823.796963-6-anup.patel@wdc.com
State Superseded
Headers show
Series RISC-V CPU Idle Support | expand

Commit Message

Anup Patel May 17, 2021, 1:08 p.m. UTC 
The generic power domain related code in PSCI domain driver is largely
independent of PSCI and can be shared with RISC-V SBI domain driver
hence we factor-out this code into dt_idle_genpd.c and dt_idle_genpd.h.

Signed-off-by: Anup Patel <anup.patel@wdc.com>
---
 drivers/cpuidle/Kconfig               |   4 +
 drivers/cpuidle/Kconfig.arm           |   1 +
 drivers/cpuidle/Makefile              |   1 +
 drivers/cpuidle/cpuidle-psci-domain.c | 138 +------------------
 drivers/cpuidle/cpuidle-psci.h        |  15 ++-
 drivers/cpuidle/dt_idle_genpd.c       | 182 ++++++++++++++++++++++++++
 drivers/cpuidle/dt_idle_genpd.h       |  50 +++++++
 7 files changed, 256 insertions(+), 135 deletions(-)
 create mode 100644 drivers/cpuidle/dt_idle_genpd.c
 create mode 100644 drivers/cpuidle/dt_idle_genpd.h

Comments

Ulf Hansson May 24, 2021, 6:01 p.m. UTC | #1 
On Mon, 17 May 2021 at 15:10, Anup Patel <anup.patel@wdc.com> wrote:
>
> The generic power domain related code in PSCI domain driver is largely
> independent of PSCI and can be shared with RISC-V SBI domain driver
> hence we factor-out this code into dt_idle_genpd.c and dt_idle_genpd.h.
>
> Signed-off-by: Anup Patel <anup.patel@wdc.com>

This is clearly a big step in the right direction. Just a couple minor
things, see more below.

Note that, I have a couple of patches in the pipe for the
cpuidle-psci-domain driver (not ready to be posted). I need a couple
of more days to confirm this restructuring still makes sense beyond
these potential new changes. I will let you know as soon as I can with
the outcome.

[...]

> diff --git a/drivers/cpuidle/dt_idle_genpd.c b/drivers/cpuidle/dt_idle_genpd.c

I think it would be a good idea to add a new section for this to the
MAINTAINERS file. Perhaps a "DT IDLE DOMAIN" section? Or perhaps you
have another idea?

In any case, I am happy to continue with maintenance of this code,
even in the new restructured form.

> new file mode 100644
> index 000000000000..5a901773db60
> --- /dev/null
> +++ b/drivers/cpuidle/dt_idle_genpd.c
> @@ -0,0 +1,182 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * PM domains for CPUs via genpd.
> + *
> + * Copyright (C) 2019 Linaro Ltd.
> + * Author: Ulf Hansson <ulf.hansson@linaro.org>
> + *
> + * Copyright (c) 2021 Western Digital Corporation or its affiliates.
> + */
> +
> +#define pr_fmt(fmt) "dt-idle-genpd: " 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/slab.h>
> +#include <linux/string.h>
> +
> +#include "dt_idle_genpd.h"
> +
> +static int dt_pd_parse_state_nodes(
> +                       int (*parse_state)(struct device_node *, u32 *),
> +                       struct genpd_power_state *states, int state_count)
> +{
> +       int i, ret;
> +       u32 state, *state_buf;
> +
> +       for (i = 0; i < state_count; i++) {
> +               ret = parse_state(to_of_node(states[i].fwnode), &state);
> +               if (ret)
> +                       goto free_state;
> +
> +               state_buf = kmalloc(sizeof(u32), GFP_KERNEL);
> +               if (!state_buf) {
> +                       ret = -ENOMEM;
> +                       goto free_state;
> +               }
> +               *state_buf = state;
> +               states[i].data = state_buf;
> +       }
> +
> +       return 0;
> +
> +free_state:
> +       i--;
> +       for (; i >= 0; i--)
> +               kfree(states[i].data);
> +       return ret;
> +}
> +
> +static int dt_pd_parse_states(struct device_node *np,
> +                       int (*parse_state)(struct device_node *, u32 *),
> +                       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 dt specifics for each found state. */
> +       ret = dt_pd_parse_state_nodes(parse_state, *states, *state_count);
> +       if (ret)
> +               kfree(*states);
> +
> +       return ret;
> +}
> +
> +static void dt_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);
> +}
> +
> +void dt_pd_free(struct generic_pm_domain *pd)
> +{
> +       dt_pd_free_states(pd->states, pd->state_count);
> +       kfree(pd->name);
> +       kfree(pd);
> +}
> +EXPORT_SYMBOL_GPL(dt_pd_free);
> +
> +struct generic_pm_domain *dt_pd_alloc(struct device_node *np,
> +                       int (*parse_state)(struct device_node *, u32 *))
> +{
> +       struct generic_pm_domain *pd;
> +       struct genpd_power_state *states = NULL;
> +       int ret, state_count = 0;
> +
> +       pd = kzalloc(sizeof(*pd), GFP_KERNEL);
> +       if (!pd)
> +               goto out;
> +
> +       pd->name = kasprintf(GFP_KERNEL, "%pOF", np);
> +       if (!pd->name)
> +               goto free_pd;
> +
> +       /*
> +        * Parse the domain idle states and let genpd manage the state selection
> +        * for those being compatible with "domain-idle-state".
> +        */
> +       ret = dt_pd_parse_states(np, parse_state, &states, &state_count);
> +       if (ret)
> +               goto free_name;
> +
> +       pd->free_states = dt_pd_free_states;
> +       pd->name = kbasename(pd->name);
> +       pd->states = states;
> +       pd->state_count = state_count;
> +
> +       pr_debug("alloc PM domain %s\n", pd->name);
> +       return pd;
> +
> +free_name:
> +       kfree(pd->name);
> +free_pd:
> +       kfree(pd);
> +out:
> +       pr_err("failed to alloc PM domain %pOF\n", np);
> +       return NULL;
> +}
> +EXPORT_SYMBOL_GPL(dt_pd_alloc);
> +
> +int dt_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;
> +}
> +EXPORT_SYMBOL_GPL(dt_pd_init_topology);

May I suggest that we stick to dt_idle_* as the prefix for all of the
exported functions in this file. Static functions can just skip the
prefix altogether.

> +
> +struct device *dt_idle_genpd_attach_cpu(int cpu, const char *name)
> +{
> +       struct device *dev;
> +
> +       dev = dev_pm_domain_attach_by_name(get_cpu_device(cpu), name);
> +       if (IS_ERR_OR_NULL(dev))
> +               return dev;
> +
> +       pm_runtime_irq_safe(dev);
> +       if (cpu_online(cpu))
> +               pm_runtime_get_sync(dev);
> +
> +       dev_pm_syscore_device(dev, true);
> +
> +       return dev;
> +}
> +EXPORT_SYMBOL_GPL(dt_idle_genpd_attach_cpu);
> +
> +void dt_idle_genpd_detach_cpu(struct device *dev)
> +{
> +       if (IS_ERR_OR_NULL(dev))
> +               return;
> +
> +       dev_pm_domain_detach(dev, false);
> +}
> +EXPORT_SYMBOL_GPL(dt_idle_genpd_detach_cpu);

Again, a minor comment on the naming of the functions. How about
skipping "genpd" in the prefix, thus just dt_idle_attach|detach_cpu()?

[...]

Kind regards
Uffe
Ulf Hansson May 25, 2021, 9:05 a.m. UTC | #2 
On Tue, 25 May 2021 at 07:39, Anup Patel <anup@brainfault.org> wrote:
>
> On Mon, May 24, 2021 at 11:31 PM Ulf Hansson <ulf.hansson@linaro.org> wrote:
> >
> > On Mon, 17 May 2021 at 15:10, Anup Patel <anup.patel@wdc.com> wrote:
> > >
> > > The generic power domain related code in PSCI domain driver is largely
> > > independent of PSCI and can be shared with RISC-V SBI domain driver
> > > hence we factor-out this code into dt_idle_genpd.c and dt_idle_genpd.h.
> > >
> > > Signed-off-by: Anup Patel <anup.patel@wdc.com>
> >
> > This is clearly a big step in the right direction. Just a couple minor
> > things, see more below.
> >
> > Note that, I have a couple of patches in the pipe for the
> > cpuidle-psci-domain driver (not ready to be posted). I need a couple
> > of more days to confirm this restructuring still makes sense beyond
> > these potential new changes. I will let you know as soon as I can with
> > the outcome.
>
> Sure, I will wait for more comments from you. I was thinking of sending
> next revision of patches sometime next week with the renaming of
> function names which you suggested.

Sounds good, that allows me a few more days this week.

>
> >
> > [...]
> >
> > > diff --git a/drivers/cpuidle/dt_idle_genpd.c b/drivers/cpuidle/dt_idle_genpd.c
> >
> > I think it would be a good idea to add a new section for this to the
> > MAINTAINERS file. Perhaps a "DT IDLE DOMAIN" section? Or perhaps you
> > have another idea?
> >
> > In any case, I am happy to continue with maintenance of this code,
> > even in the new restructured form.
>
> Yes, a separate "DT IDLE DOMAIN" section in MAINTAINERS file
> sounds good to me.
>
> Anyway the dt_idle_genpd is factored-out code from cpuidle-psci-domain.c
> so I suggest you to maintain dt_idle_genpd as well.
>
> Do you want me to add a "DT IDLE DOMAIN" section in the
> MAINTAINERS file as part of this patch ??

Yeah, that works for me. Perhaps extend it to .. PM DOMAIN though.

[...]

Kind regards
Uffe
Ulf Hansson May 28, 2021, 9:26 a.m. UTC | #3 
On Tue, 25 May 2021 at 11:05, Ulf Hansson <ulf.hansson@linaro.org> wrote:
>
> On Tue, 25 May 2021 at 07:39, Anup Patel <anup@brainfault.org> wrote:
> >
> > On Mon, May 24, 2021 at 11:31 PM Ulf Hansson <ulf.hansson@linaro.org> wrote:
> > >
> > > On Mon, 17 May 2021 at 15:10, Anup Patel <anup.patel@wdc.com> wrote:
> > > >
> > > > The generic power domain related code in PSCI domain driver is largely
> > > > independent of PSCI and can be shared with RISC-V SBI domain driver
> > > > hence we factor-out this code into dt_idle_genpd.c and dt_idle_genpd.h.
> > > >
> > > > Signed-off-by: Anup Patel <anup.patel@wdc.com>
> > >
> > > This is clearly a big step in the right direction. Just a couple minor
> > > things, see more below.
> > >
> > > Note that, I have a couple of patches in the pipe for the
> > > cpuidle-psci-domain driver (not ready to be posted). I need a couple
> > > of more days to confirm this restructuring still makes sense beyond
> > > these potential new changes. I will let you know as soon as I can with
> > > the outcome.
> >
> > Sure, I will wait for more comments from you. I was thinking of sending
> > next revision of patches sometime next week with the renaming of
> > function names which you suggested.
>
> Sounds good, that allows me a few more days this week.

I don't have any further comments at this point. It looks good to me,
but let me have a quick review on the next version before I provide my
ack.

[...]

Kind regards
Uffe
diff mbox series

Patch

diff --git a/drivers/cpuidle/Kconfig b/drivers/cpuidle/Kconfig
index c0aeedd66f02..f1afe7ab6b54 100644
--- a/drivers/cpuidle/Kconfig
+++ b/drivers/cpuidle/Kconfig
@@ -47,6 +47,10 @@  config CPU_IDLE_GOV_HALTPOLL
 config DT_IDLE_STATES
 	bool
 
+config DT_IDLE_GENPD
+	depends on PM_GENERIC_DOMAINS_OF
+	bool
+
 menu "ARM CPU Idle Drivers"
 depends on ARM || ARM64
 source "drivers/cpuidle/Kconfig.arm"
diff --git a/drivers/cpuidle/Kconfig.arm b/drivers/cpuidle/Kconfig.arm
index 334f83e56120..be12a9ca78f0 100644
--- a/drivers/cpuidle/Kconfig.arm
+++ b/drivers/cpuidle/Kconfig.arm
@@ -27,6 +27,7 @@  config ARM_PSCI_CPUIDLE_DOMAIN
 	bool "PSCI CPU idle Domain"
 	depends on ARM_PSCI_CPUIDLE
 	depends on PM_GENERIC_DOMAINS_OF
+	select DT_IDLE_GENPD
 	default y
 	help
 	  Select this to enable the PSCI based CPUidle driver to use PM domains,
diff --git a/drivers/cpuidle/Makefile b/drivers/cpuidle/Makefile
index 26bbc5e74123..11a26cef279f 100644
--- a/drivers/cpuidle/Makefile
+++ b/drivers/cpuidle/Makefile
@@ -6,6 +6,7 @@ 
 obj-y += cpuidle.o driver.o governor.o sysfs.o governors/
 obj-$(CONFIG_ARCH_NEEDS_CPU_IDLE_COUPLED) += coupled.o
 obj-$(CONFIG_DT_IDLE_STATES)		  += dt_idle_states.o
+obj-$(CONFIG_DT_IDLE_GENPD)		  += dt_idle_genpd.o
 obj-$(CONFIG_ARCH_HAS_CPU_RELAX)	  += poll_state.o
 obj-$(CONFIG_HALTPOLL_CPUIDLE)		  += cpuidle-haltpoll.o
 
diff --git a/drivers/cpuidle/cpuidle-psci-domain.c b/drivers/cpuidle/cpuidle-psci-domain.c
index ff2c3f8e4668..3ceec0ee9f02 100644
--- a/drivers/cpuidle/cpuidle-psci-domain.c
+++ b/drivers/cpuidle/cpuidle-psci-domain.c
@@ -47,73 +47,14 @@  static int psci_pd_power_off(struct generic_pm_domain *pd)
 	return 0;
 }
 
-static int 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 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 psci_pd_init(struct device_node *np, bool use_osi)
 {
 	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);
+	pd = dt_pd_alloc(np, psci_dt_parse_state_node);
 	if (!pd)
 		goto out;
 
@@ -121,22 +62,6 @@  static int psci_pd_init(struct device_node *np, bool use_osi)
 	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->states = states;
-	pd->state_count = state_count;
 	pd->flags |= GENPD_FLAG_IRQ_SAFE | GENPD_FLAG_CPU_DOMAIN;
 
 	/* Allow power off when OSI has been successfully enabled. */
@@ -149,10 +74,8 @@  static int psci_pd_init(struct device_node *np, bool use_osi)
 	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;
-	}
+	if (ret)
+		goto free_pd_prov;
 
 	ret = of_genpd_add_provider_simple(np, pd);
 	if (ret)
@@ -166,12 +89,10 @@  static int psci_pd_init(struct device_node *np, bool use_osi)
 
 remove_pd:
 	pm_genpd_remove(pd);
-free_name:
-	kfree(pd->name);
 free_pd_prov:
 	kfree(pd_provider);
 free_pd:
-	kfree(pd);
+	dt_pd_free(pd);
 out:
 	pr_err("failed to init PM domain ret=%d %pOF\n", ret, np);
 	return ret;
@@ -195,30 +116,6 @@  static void psci_pd_remove(void)
 	}
 }
 
-static int 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 bool psci_pd_try_set_osi_mode(void)
 {
 	int ret;
@@ -282,7 +179,7 @@  static int psci_cpuidle_domain_probe(struct platform_device *pdev)
 		goto no_pd;
 
 	/* Link genpd masters/subdomains to model the CPU topology. */
-	ret = psci_pd_init_topology(np);
+	ret = dt_pd_init_topology(np);
 	if (ret)
 		goto remove_pd;
 
@@ -314,28 +211,3 @@  static int __init psci_idle_init_domains(void)
 	return platform_driver_register(&psci_cpuidle_domain_driver);
 }
 subsys_initcall(psci_idle_init_domains);
-
-struct device *psci_dt_attach_cpu(int cpu)
-{
-	struct device *dev;
-
-	dev = dev_pm_domain_attach_by_name(get_cpu_device(cpu), "psci");
-	if (IS_ERR_OR_NULL(dev))
-		return dev;
-
-	pm_runtime_irq_safe(dev);
-	if (cpu_online(cpu))
-		pm_runtime_get_sync(dev);
-
-	dev_pm_syscore_device(dev, true);
-
-	return dev;
-}
-
-void psci_dt_detach_cpu(struct device *dev)
-{
-	if (IS_ERR_OR_NULL(dev))
-		return;
-
-	dev_pm_domain_detach(dev, false);
-}
diff --git a/drivers/cpuidle/cpuidle-psci.h b/drivers/cpuidle/cpuidle-psci.h
index d8e925e84c27..70de1e3c00af 100644
--- a/drivers/cpuidle/cpuidle-psci.h
+++ b/drivers/cpuidle/cpuidle-psci.h
@@ -10,8 +10,19 @@  void psci_set_domain_state(u32 state);
 int psci_dt_parse_state_node(struct device_node *np, u32 *state);
 
 #ifdef CONFIG_ARM_PSCI_CPUIDLE_DOMAIN
-struct device *psci_dt_attach_cpu(int cpu);
-void psci_dt_detach_cpu(struct device *dev);
+
+#include "dt_idle_genpd.h"
+
+static inline struct device *psci_dt_attach_cpu(int cpu)
+{
+	return dt_idle_genpd_attach_cpu(cpu, "psci");
+}
+
+static inline void psci_dt_detach_cpu(struct device *dev)
+{
+	dt_idle_genpd_detach_cpu(dev);
+}
+
 #else
 static inline struct device *psci_dt_attach_cpu(int cpu) { return NULL; }
 static inline void psci_dt_detach_cpu(struct device *dev) { }
diff --git a/drivers/cpuidle/dt_idle_genpd.c b/drivers/cpuidle/dt_idle_genpd.c
new file mode 100644
index 000000000000..5a901773db60
--- /dev/null
+++ b/drivers/cpuidle/dt_idle_genpd.c
@@ -0,0 +1,182 @@ 
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * PM domains for CPUs via genpd.
+ *
+ * Copyright (C) 2019 Linaro Ltd.
+ * Author: Ulf Hansson <ulf.hansson@linaro.org>
+ *
+ * Copyright (c) 2021 Western Digital Corporation or its affiliates.
+ */
+
+#define pr_fmt(fmt) "dt-idle-genpd: " 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/slab.h>
+#include <linux/string.h>
+
+#include "dt_idle_genpd.h"
+
+static int dt_pd_parse_state_nodes(
+			int (*parse_state)(struct device_node *, u32 *),
+			struct genpd_power_state *states, int state_count)
+{
+	int i, ret;
+	u32 state, *state_buf;
+
+	for (i = 0; i < state_count; i++) {
+		ret = parse_state(to_of_node(states[i].fwnode), &state);
+		if (ret)
+			goto free_state;
+
+		state_buf = kmalloc(sizeof(u32), GFP_KERNEL);
+		if (!state_buf) {
+			ret = -ENOMEM;
+			goto free_state;
+		}
+		*state_buf = state;
+		states[i].data = state_buf;
+	}
+
+	return 0;
+
+free_state:
+	i--;
+	for (; i >= 0; i--)
+		kfree(states[i].data);
+	return ret;
+}
+
+static int dt_pd_parse_states(struct device_node *np,
+			int (*parse_state)(struct device_node *, u32 *),
+			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 dt specifics for each found state. */
+	ret = dt_pd_parse_state_nodes(parse_state, *states, *state_count);
+	if (ret)
+		kfree(*states);
+
+	return ret;
+}
+
+static void dt_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);
+}
+
+void dt_pd_free(struct generic_pm_domain *pd)
+{
+	dt_pd_free_states(pd->states, pd->state_count);
+	kfree(pd->name);
+	kfree(pd);
+}
+EXPORT_SYMBOL_GPL(dt_pd_free);
+
+struct generic_pm_domain *dt_pd_alloc(struct device_node *np,
+			int (*parse_state)(struct device_node *, u32 *))
+{
+	struct generic_pm_domain *pd;
+	struct genpd_power_state *states = NULL;
+	int ret, state_count = 0;
+
+	pd = kzalloc(sizeof(*pd), GFP_KERNEL);
+	if (!pd)
+		goto out;
+
+	pd->name = kasprintf(GFP_KERNEL, "%pOF", np);
+	if (!pd->name)
+		goto free_pd;
+
+	/*
+	 * Parse the domain idle states and let genpd manage the state selection
+	 * for those being compatible with "domain-idle-state".
+	 */
+	ret = dt_pd_parse_states(np, parse_state, &states, &state_count);
+	if (ret)
+		goto free_name;
+
+	pd->free_states = dt_pd_free_states;
+	pd->name = kbasename(pd->name);
+	pd->states = states;
+	pd->state_count = state_count;
+
+	pr_debug("alloc PM domain %s\n", pd->name);
+	return pd;
+
+free_name:
+	kfree(pd->name);
+free_pd:
+	kfree(pd);
+out:
+	pr_err("failed to alloc PM domain %pOF\n", np);
+	return NULL;
+}
+EXPORT_SYMBOL_GPL(dt_pd_alloc);
+
+int dt_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;
+}
+EXPORT_SYMBOL_GPL(dt_pd_init_topology);
+
+struct device *dt_idle_genpd_attach_cpu(int cpu, const char *name)
+{
+	struct device *dev;
+
+	dev = dev_pm_domain_attach_by_name(get_cpu_device(cpu), name);
+	if (IS_ERR_OR_NULL(dev))
+		return dev;
+
+	pm_runtime_irq_safe(dev);
+	if (cpu_online(cpu))
+		pm_runtime_get_sync(dev);
+
+	dev_pm_syscore_device(dev, true);
+
+	return dev;
+}
+EXPORT_SYMBOL_GPL(dt_idle_genpd_attach_cpu);
+
+void dt_idle_genpd_detach_cpu(struct device *dev)
+{
+	if (IS_ERR_OR_NULL(dev))
+		return;
+
+	dev_pm_domain_detach(dev, false);
+}
+EXPORT_SYMBOL_GPL(dt_idle_genpd_detach_cpu);
diff --git a/drivers/cpuidle/dt_idle_genpd.h b/drivers/cpuidle/dt_idle_genpd.h
new file mode 100644
index 000000000000..23ebf6050e74
--- /dev/null
+++ b/drivers/cpuidle/dt_idle_genpd.h
@@ -0,0 +1,50 @@ 
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __DT_IDLE_GENPD
+#define __DT_IDLE_GENPD
+
+struct device_node;
+struct generic_pm_domain;
+
+#ifdef CONFIG_DT_IDLE_GENPD
+
+void dt_pd_free(struct generic_pm_domain *pd);
+
+struct generic_pm_domain *dt_pd_alloc(struct device_node *np,
+			int (*parse_state)(struct device_node *, u32 *));
+
+int dt_pd_init_topology(struct device_node *np);
+
+struct device *dt_idle_genpd_attach_cpu(int cpu, const char *name);
+
+void dt_idle_genpd_detach_cpu(struct device *dev);
+
+#else
+
+static inline void dt_pd_free(struct generic_pm_domain *pd)
+{
+}
+
+static inline struct generic_pm_domain *dt_pd_alloc(struct device_node *np,
+			int (*parse_state)(struct device_node *, u32 *));
+{
+	return NULL;
+}
+
+static inline int dt_pd_init_topology(struct device_node *np)
+{
+	return 0;
+}
+
+static inline struct device *dt_idle_genpd_attach_cpu(int cpu,
+						      const char *name)
+{
+	return NULL;
+}
+
+static inline void dt_idle_genpd_detach_cpu(struct device *dev)
+{
+}
+
+#endif
+
+#endif