[PATCH v3 2/9] PM / Domains: Add generic OF-based PM domain look-up
Rafael J. Wysocki
rjw at rjwysocki.net
Sun Sep 7 15:13:36 PDT 2014
On Thursday, September 04, 2014 03:52:29 PM Ulf Hansson wrote:
> From: Tomasz Figa <t.figa at samsung.com>
>
> This patch introduces generic code to perform PM domain look-up using
> device tree and automatically bind devices to their PM domains.
>
> Generic device tree bindings are introduced to specify PM domains of
> devices in their device tree nodes.
>
> Backwards compatibility with legacy Samsung-specific PM domain bindings
> is provided, but for now the new code is not compiled when
> CONFIG_ARCH_EXYNOS is selected to avoid collision with legacy code.
> This will change as soon as the Exynos PM domain code gets converted to
> use the generic framework in further patch.
>
> Signed-off-by: Tomasz Figa <t.figa at samsung.com>
> Signed-off-by: Ulf Hansson <ulf.hansson at linaro.org>
> [Ulf:Added attach|detach functions, fixed review comments]
> Tested-by: Philipp Zabel <p.zabel at pengutronix.de>
However, for this one (and consequently the rest) I need an ACK from the
people who maintain the bindings.
> ---
> .../devicetree/bindings/power/power_domain.txt | 49 ++++
> drivers/base/power/domain.c | 291 +++++++++++++++++++++
> include/linux/pm_domain.h | 57 ++++
> kernel/power/Kconfig | 4 +
> 4 files changed, 401 insertions(+)
> create mode 100644 Documentation/devicetree/bindings/power/power_domain.txt
>
> diff --git a/Documentation/devicetree/bindings/power/power_domain.txt b/Documentation/devicetree/bindings/power/power_domain.txt
> new file mode 100644
> index 0000000..98c1667
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/power/power_domain.txt
> @@ -0,0 +1,49 @@
> +* Generic PM domains
> +
> +System on chip designs are often divided into multiple PM domains that can be
> +used for power gating of selected IP blocks for power saving by reduced leakage
> +current.
> +
> +This device tree binding can be used to bind PM domain consumer devices with
> +their PM domains provided by PM domain providers. A PM domain provider can be
> +represented by any node in the device tree and can provide one or more PM
> +domains. A consumer node can refer to the provider by a phandle and a set of
> +phandle arguments (so called PM domain specifiers) of length specified by the
> +#power-domain-cells property in the PM domain provider node.
> +
> +==PM domain providers==
> +
> +Required properties:
> + - #power-domain-cells : Number of cells in a PM domain specifier;
> + Typically 0 for nodes representing a single PM domain and 1 for nodes
> + providing multiple PM domains (e.g. power controllers), but can be any value
> + as specified by device tree binding documentation of particular provider.
> +
> +Example:
> +
> + power: power-controller at 12340000 {
> + compatible = "foo,power-controller";
> + reg = <0x12340000 0x1000>;
> + #power-domain-cells = <1>;
> + };
> +
> +The node above defines a power controller that is a PM domain provider and
> +expects one cell as its phandle argument.
> +
> +==PM domain consumers==
> +
> +Required properties:
> + - power-domains : A phandle and PM domain specifier as defined by bindings of
> + the power controller specified by phandle.
> +
> +Example:
> +
> + leaky-device at 12350000 {
> + compatible = "foo,i-leak-current";
> + reg = <0x12350000 0x1000>;
> + power-domains = <&power 0>;
> + };
> +
> +The node above defines a typical PM domain consumer device, which is located
> +inside a PM domain with index 0 of a power controller represented by a node
> +with the label "power".
> diff --git a/drivers/base/power/domain.c b/drivers/base/power/domain.c
> index eee55c1..ed42651 100644
> --- a/drivers/base/power/domain.c
> +++ b/drivers/base/power/domain.c
> @@ -8,6 +8,7 @@
>
> #include <linux/kernel.h>
> #include <linux/io.h>
> +#include <linux/platform_device.h>
> #include <linux/pm_runtime.h>
> #include <linux/pm_domain.h>
> #include <linux/pm_qos.h>
> @@ -2189,3 +2190,293 @@ void pm_genpd_init(struct generic_pm_domain *genpd,
> list_add(&genpd->gpd_list_node, &gpd_list);
> mutex_unlock(&gpd_list_lock);
> }
> +
> +#ifdef CONFIG_PM_GENERIC_DOMAINS_OF
> +/*
> + * Device Tree based PM domain providers.
> + *
> + * The code below implements generic device tree based PM domain providers that
> + * bind device tree nodes with generic PM domains registered in the system.
> + *
> + * Any driver that registers generic PM domains and needs to support binding of
> + * devices to these domains is supposed to register a PM domain provider, which
> + * maps a PM domain specifier retrieved from the device tree to a PM domain.
> + *
> + * Two simple mapping functions have been provided for convenience:
> + * - __of_genpd_xlate_simple() for 1:1 device tree node to PM domain mapping.
> + * - __of_genpd_xlate_onecell() for mapping of multiple PM domains per node by
> + * index.
> + */
> +
> +/**
> + * struct of_genpd_provider - PM domain provider registration structure
> + * @link: Entry in global list of PM domain providers
> + * @node: Pointer to device tree node of PM domain provider
> + * @xlate: Provider-specific xlate callback mapping a set of specifier cells
> + * into a PM domain.
> + * @data: context pointer to be passed into @xlate callback
> + */
> +struct of_genpd_provider {
> + struct list_head link;
> + struct device_node *node;
> + genpd_xlate_t xlate;
> + void *data;
> +};
> +
> +/* List of registered PM domain providers. */
> +static LIST_HEAD(of_genpd_providers);
> +/* Mutex to protect the list above. */
> +static DEFINE_MUTEX(of_genpd_mutex);
> +
> +/**
> + * __of_genpd_xlate_simple() - Xlate function for direct node-domain mapping
> + * @genpdspec: OF phandle args to map into a PM domain
> + * @data: xlate function private data - pointer to struct generic_pm_domain
> + *
> + * This is a generic xlate function that can be used to model PM domains that
> + * have their own device tree nodes. The private data of xlate function needs
> + * to be a valid pointer to struct generic_pm_domain.
> + */
> +struct generic_pm_domain *__of_genpd_xlate_simple(
> + struct of_phandle_args *genpdspec,
> + void *data)
> +{
> + if (genpdspec->args_count != 0)
> + return ERR_PTR(-EINVAL);
> + return data;
> +}
> +EXPORT_SYMBOL_GPL(__of_genpd_xlate_simple);
> +
> +/**
> + * __of_genpd_xlate_onecell() - Xlate function using a single index.
> + * @genpdspec: OF phandle args to map into a PM domain
> + * @data: xlate function private data - pointer to struct genpd_onecell_data
> + *
> + * This is a generic xlate function that can be used to model simple PM domain
> + * controllers that have one device tree node and provide multiple PM domains.
> + * A single cell is used as an index into an array of PM domains specified in
> + * the genpd_onecell_data struct when registering the provider.
> + */
> +struct generic_pm_domain *__of_genpd_xlate_onecell(
> + struct of_phandle_args *genpdspec,
> + void *data)
> +{
> + struct genpd_onecell_data *genpd_data = data;
> + unsigned int idx = genpdspec->args[0];
> +
> + if (genpdspec->args_count != 1)
> + return ERR_PTR(-EINVAL);
> +
> + if (idx >= genpd_data->num_domains) {
> + pr_err("%s: invalid domain index %u\n", __func__, idx);
> + return ERR_PTR(-EINVAL);
> + }
> +
> + if (!genpd_data->domains[idx])
> + return ERR_PTR(-ENOENT);
> +
> + return genpd_data->domains[idx];
> +}
> +EXPORT_SYMBOL_GPL(__of_genpd_xlate_onecell);
> +
> +/**
> + * __of_genpd_add_provider() - Register a PM domain provider for a node
> + * @np: Device node pointer associated with the PM domain provider.
> + * @xlate: Callback for decoding PM domain from phandle arguments.
> + * @data: Context pointer for @xlate callback.
> + */
> +int __of_genpd_add_provider(struct device_node *np, genpd_xlate_t xlate,
> + void *data)
> +{
> + struct of_genpd_provider *cp;
> +
> + cp = kzalloc(sizeof(*cp), GFP_KERNEL);
> + if (!cp)
> + return -ENOMEM;
> +
> + cp->node = of_node_get(np);
> + cp->data = data;
> + cp->xlate = xlate;
> +
> + mutex_lock(&of_genpd_mutex);
> + list_add(&cp->link, &of_genpd_providers);
> + mutex_unlock(&of_genpd_mutex);
> + pr_debug("Added domain provider from %s\n", np->full_name);
> +
> + return 0;
> +}
> +EXPORT_SYMBOL_GPL(__of_genpd_add_provider);
> +
> +/**
> + * of_genpd_del_provider() - Remove a previously registered PM domain provider
> + * @np: Device node pointer associated with the PM domain provider
> + */
> +void of_genpd_del_provider(struct device_node *np)
> +{
> + struct of_genpd_provider *cp;
> +
> + mutex_lock(&of_genpd_mutex);
> + list_for_each_entry(cp, &of_genpd_providers, link) {
> + if (cp->node == np) {
> + list_del(&cp->link);
> + of_node_put(cp->node);
> + kfree(cp);
> + break;
> + }
> + }
> + mutex_unlock(&of_genpd_mutex);
> +}
> +EXPORT_SYMBOL_GPL(of_genpd_del_provider);
> +
> +/**
> + * of_genpd_get_from_provider() - Look-up PM domain
> + * @genpdspec: OF phandle args to use for look-up
> + *
> + * Looks for a PM domain provider under the node specified by @genpdspec and if
> + * found, uses xlate function of the provider to map phandle args to a PM
> + * domain.
> + *
> + * Returns a valid pointer to struct generic_pm_domain on success or ERR_PTR()
> + * on failure.
> + */
> +static struct generic_pm_domain *of_genpd_get_from_provider(
> + struct of_phandle_args *genpdspec)
> +{
> + struct generic_pm_domain *genpd = ERR_PTR(-ENOENT);
> + struct of_genpd_provider *provider;
> +
> + mutex_lock(&of_genpd_mutex);
> +
> + /* Check if we have such a provider in our array */
> + list_for_each_entry(provider, &of_genpd_providers, link) {
> + if (provider->node == genpdspec->np)
> + genpd = provider->xlate(genpdspec, provider->data);
> + if (!IS_ERR(genpd))
> + break;
> + }
> +
> + mutex_unlock(&of_genpd_mutex);
> +
> + return genpd;
> +}
> +
> +/**
> + * genpd_dev_pm_attach - Attach a device to its PM domain using DT.
> + * @dev: Device to attach.
> + *
> + * Parse device's OF node to find a PM domain specifier. If such is found,
> + * attaches the device to retrieved pm_domain ops.
> + *
> + * Both generic and legacy Samsung-specific DT bindings are supported to keep
> + * backwards compatibility with existing DTBs.
> + *
> + * Returns 0 on successfully attached PM domain or negative error code.
> + */
> +int genpd_dev_pm_attach(struct device *dev)
> +{
> + struct of_phandle_args pd_args;
> + struct generic_pm_domain *pd;
> + int ret;
> +
> + if (!dev->of_node)
> + return -ENODEV;
> +
> + if (dev->pm_domain)
> + return -EEXIST;
> +
> + ret = of_parse_phandle_with_args(dev->of_node, "power-domains",
> + "#power-domain-cells", 0, &pd_args);
> + if (ret < 0) {
> + if (ret != -ENOENT)
> + return ret;
> +
> + /*
> + * Try legacy Samsung-specific bindings
> + * (for backwards compatibility of DT ABI)
> + */
> + pd_args.args_count = 0;
> + pd_args.np = of_parse_phandle(dev->of_node,
> + "samsung,power-domain", 0);
> + if (!pd_args.np)
> + return -ENOENT;
> + }
> +
> + pd = of_genpd_get_from_provider(&pd_args);
> + if (IS_ERR(pd)) {
> + dev_dbg(dev, "%s() failed to find PM domain: %ld\n",
> + __func__, PTR_ERR(pd));
> + of_node_put(dev->of_node);
> + return PTR_ERR(pd);
> + }
> +
> + dev_dbg(dev, "adding to PM domain %s\n", pd->name);
> +
> + while (1) {
> + ret = pm_genpd_add_device(pd, dev);
> + if (ret != -EAGAIN)
> + break;
> + cond_resched();
> + }
> +
> + if (ret < 0) {
> + dev_err(dev, "failed to add to PM domain %s: %d",
> + pd->name, ret);
> + of_node_put(dev->of_node);
> + return ret;
> + }
> +
> + return 0;
> +}
> +EXPORT_SYMBOL_GPL(genpd_dev_pm_attach);
> +
> +/**
> + * genpd_dev_pm_detach - Detach a device from its PM domain.
> + * @dev: Device to attach.
> + *
> + * Try to locate a corresponding generic PM domain, which the device was
> + * attached to previously. If such is found, the device is detached from it.
> + *
> + * Returns 0 on successfully detached PM domain or negative error code.
> + */
> +int genpd_dev_pm_detach(struct device *dev)
> +{
> + struct generic_pm_domain *pd = NULL, *gpd;
> + int ret = 0;
> +
> + if (!dev->pm_domain)
> + return -ENODEV;
> +
> + mutex_lock(&gpd_list_lock);
> + list_for_each_entry(gpd, &gpd_list, gpd_list_node) {
> + if (&gpd->domain == dev->pm_domain) {
> + pd = gpd;
> + break;
> + }
> + }
> + mutex_unlock(&gpd_list_lock);
> +
> + if (!pd)
> + return -ENOENT;
> +
> + dev_dbg(dev, "removing from PM domain %s\n", pd->name);
> +
> + while (1) {
> + ret = pm_genpd_remove_device(pd, dev);
> + if (ret != -EAGAIN)
> + break;
> + cond_resched();
> + }
> +
> + if (ret < 0) {
> + dev_err(dev, "failed to remove from PM domain %s: %d",
> + pd->name, ret);
> + return ret;
> + }
> +
> + /* Check if PM domain can be powered off after removing this device. */
> + genpd_queue_power_off_work(pd);
> +
> + return 0;
> +}
> +EXPORT_SYMBOL_GPL(genpd_dev_pm_detach);
> +#endif
> diff --git a/include/linux/pm_domain.h b/include/linux/pm_domain.h
> index ebc4c76..b09eaa7 100644
> --- a/include/linux/pm_domain.h
> +++ b/include/linux/pm_domain.h
> @@ -310,4 +310,61 @@ static inline void pm_genpd_syscore_poweron(struct device *dev)
> pm_genpd_syscore_switch(dev, false);
> }
>
> +/* OF PM domain providers */
> +struct of_device_id;
> +
> +struct genpd_onecell_data {
> + struct generic_pm_domain **domains;
> + unsigned int num_domains;
> +};
> +
> +typedef struct generic_pm_domain *(*genpd_xlate_t)(struct of_phandle_args *args,
> + void *data);
> +
> +#ifdef CONFIG_PM_GENERIC_DOMAINS_OF
> +int __of_genpd_add_provider(struct device_node *np, genpd_xlate_t xlate,
> + void *data);
> +void of_genpd_del_provider(struct device_node *np);
> +
> +struct generic_pm_domain *__of_genpd_xlate_simple(
> + struct of_phandle_args *genpdspec,
> + void *data);
> +struct generic_pm_domain *__of_genpd_xlate_onecell(
> + struct of_phandle_args *genpdspec,
> + void *data);
> +
> +int genpd_dev_pm_attach(struct device *dev);
> +int genpd_dev_pm_detach(struct device *dev);
> +#else /* !CONFIG_PM_GENERIC_DOMAINS_OF */
> +static inline int __of_genpd_add_provider(struct device_node *np,
> + genpd_xlate_t xlate, void *data)
> +{
> + return 0;
> +}
> +static inline void of_genpd_del_provider(struct device_node *np) {}
> +
> +#define __of_genpd_xlate_simple NULL
> +#define __of_genpd_xlate_onecell NULL
> +
> +static inline int genpd_dev_pm_attach(struct device *dev)
> +{
> + return -ENODEV;
> +}
> +static inline int genpd_dev_pm_detach(struct device *dev)
> +{
> + return -ENODEV;
> +}
> +#endif /* CONFIG_PM_GENERIC_DOMAINS_OF */
> +
> +static inline int of_genpd_add_provider_simple(struct device_node *np,
> + struct generic_pm_domain *genpd)
> +{
> + return __of_genpd_add_provider(np, __of_genpd_xlate_simple, genpd);
> +}
> +static inline int of_genpd_add_provider_onecell(struct device_node *np,
> + struct genpd_onecell_data *data)
> +{
> + return __of_genpd_add_provider(np, __of_genpd_xlate_onecell, data);
> +}
> +
> #endif /* _LINUX_PM_DOMAIN_H */
> diff --git a/kernel/power/Kconfig b/kernel/power/Kconfig
> index e4e4121..897619b 100644
> --- a/kernel/power/Kconfig
> +++ b/kernel/power/Kconfig
> @@ -302,6 +302,10 @@ config PM_GENERIC_DOMAINS_RUNTIME
> def_bool y
> depends on PM_RUNTIME && PM_GENERIC_DOMAINS
>
> +config PM_GENERIC_DOMAINS_OF
> + def_bool y
> + depends on PM_GENERIC_DOMAINS && OF && !ARCH_EXYNOS
> +
> config CPU_PM
> bool
> depends on SUSPEND || CPU_IDLE
>
--
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.
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