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Date: Thu, 10 Dec 2015 09:55:16 +0000
From: Lee Jones <lee.jones@...aro.org>
To: Viresh Kumar <viresh.kumar@...aro.org>
Cc: Rafael Wysocki <rjw@...ysocki.net>, Nishanth Menon <nm@...com>,
Len Brown <len.brown@...el.com>,
Linaro Kernel Mailman List <linaro-kernel@...ts.linaro.org>,
"linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
Stephen Boyd <sboyd@...eaurora.org>,
open list <linux-kernel@...r.kernel.org>,
Pavel Machek <pavel@....cz>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
Viresh Kumar <vireshk@...nel.org>
Subject: Re: [PATCH V3 1/2] PM / OPP: Parse 'opp-supported-hw' binding
On 9 December 2015 at 02:31, Viresh Kumar <viresh.kumar@...aro.org> wrote:
> OPP bindings allow a platform to enable OPPs based on the version of the
> hardware they are used for.
>
> Add support to the OPP-core to parse these bindings, by introducing
> dev_pm_opp_{set|put}_supported_hw() APIs.
>
> Signed-off-by: Viresh Kumar <viresh.kumar@...aro.org>
> ---
> drivers/base/power/opp/core.c | 148 ++++++++++++++++++++++++++++++++++++++++++
> drivers/base/power/opp/opp.h | 5 ++
> include/linux/pm_opp.h | 13 ++++
> 3 files changed, 166 insertions(+)
Tested-by: Lee Jones <lee.jones@...aro.org>
> diff --git a/drivers/base/power/opp/core.c b/drivers/base/power/opp/core.c
> index 6aa172be6e8e..55cf1a99b532 100644
> --- a/drivers/base/power/opp/core.c
> +++ b/drivers/base/power/opp/core.c
> @@ -559,6 +559,9 @@ static void _remove_device_opp(struct device_opp *dev_opp)
> if (!list_empty(&dev_opp->opp_list))
> return;
>
> + if (dev_opp->supported_hw)
> + return;
> +
> list_dev = list_first_entry(&dev_opp->dev_list, struct device_list_opp,
> node);
>
> @@ -834,6 +837,145 @@ static int opp_parse_supplies(struct dev_pm_opp *opp, struct device *dev)
> }
>
> /**
> + * dev_pm_opp_set_supported_hw() - Set supported platforms
> + * @dev: Device for which supported-hw has to be set.
> + * @versions: Array of hierarchy of versions to match.
> + * @count: Number of elements in the array.
> + *
> + * This is required only for the V2 bindings, and it enables a platform to
> + * specify the hierarchy of versions it supports. OPP layer will then enable
> + * OPPs, which are available for those versions, based on its 'opp-supported-hw'
> + * property.
> + *
> + * Locking: The internal device_opp and opp structures are RCU protected.
> + * Hence this function internally uses RCU updater strategy with mutex locks
> + * to keep the integrity of the internal data structures. Callers should ensure
> + * that this function is *NOT* called under RCU protection or in contexts where
> + * mutex cannot be locked.
> + */
> +int dev_pm_opp_set_supported_hw(struct device *dev, const u32 *versions,
> + unsigned int count)
> +{
> + struct device_opp *dev_opp;
> + int ret = 0;
> +
> + /* Hold our list modification lock here */
> + mutex_lock(&dev_opp_list_lock);
> +
> + dev_opp = _add_device_opp(dev);
> + if (!dev_opp) {
> + ret = -ENOMEM;
> + goto unlock;
> + }
> +
> + /* Make sure there are no concurrent readers while updating dev_opp */
> + WARN_ON(!list_empty(&dev_opp->opp_list));
> +
> + /* Do we already have a version hierarchy associated with dev_opp? */
> + if (dev_opp->supported_hw) {
> + dev_err(dev, "%s: Already have supported hardware list\n",
> + __func__);
> + ret = -EBUSY;
> + goto err;
> + }
> +
> + dev_opp->supported_hw = kmemdup(versions, count * sizeof(*versions),
> + GFP_KERNEL);
> + if (!dev_opp->supported_hw) {
> + ret = -ENOMEM;
> + goto err;
> + }
> +
> + dev_opp->supported_hw_count = count;
> + mutex_unlock(&dev_opp_list_lock);
> + return 0;
> +
> +err:
> + _remove_device_opp(dev_opp);
> +unlock:
> + mutex_unlock(&dev_opp_list_lock);
> +
> + return ret;
> +}
> +EXPORT_SYMBOL_GPL(dev_pm_opp_set_supported_hw);
> +
> +/**
> + * dev_pm_opp_put_supported_hw() - Releases resources blocked for supported hw
> + * @dev: Device for which supported-hw has to be set.
> + *
> + * This is required only for the V2 bindings, and is called for a matching
> + * dev_pm_opp_set_supported_hw(). Until this is called, the device_opp structure
> + * will not be freed.
> + *
> + * Locking: The internal device_opp and opp structures are RCU protected.
> + * Hence this function internally uses RCU updater strategy with mutex locks
> + * to keep the integrity of the internal data structures. Callers should ensure
> + * that this function is *NOT* called under RCU protection or in contexts where
> + * mutex cannot be locked.
> + */
> +void dev_pm_opp_put_supported_hw(struct device *dev)
> +{
> + struct device_opp *dev_opp;
> +
> + /* Hold our list modification lock here */
> + mutex_lock(&dev_opp_list_lock);
> +
> + /* Check for existing list for 'dev' first */
> + dev_opp = _find_device_opp(dev);
> + if (IS_ERR(dev_opp)) {
> + dev_err(dev, "Failed to find dev_opp: %ld\n", PTR_ERR(dev_opp));
> + goto unlock;
> + }
> +
> + /* Make sure there are no concurrent readers while updating dev_opp */
> + WARN_ON(!list_empty(&dev_opp->opp_list));
> +
> + if (!dev_opp->supported_hw) {
> + dev_err(dev, "%s: Doesn't have supported hardware list\n",
> + __func__);
> + goto unlock;
> + }
> +
> + kfree(dev_opp->supported_hw);
> + dev_opp->supported_hw = NULL;
> + dev_opp->supported_hw_count = 0;
> +
> + /* Try freeing device_opp if this was the last blocking resource */
> + _remove_device_opp(dev_opp);
> +
> +unlock:
> + mutex_unlock(&dev_opp_list_lock);
> +}
> +EXPORT_SYMBOL_GPL(dev_pm_opp_put_supported_hw);
> +
> +static bool _opp_is_supported(struct device *dev, struct device_opp *dev_opp,
> + struct device_node *np)
> +{
> + unsigned int count = dev_opp->supported_hw_count;
> + u32 version;
> + int ret;
> +
> + if (!dev_opp->supported_hw)
> + return true;
> +
> + while (count--) {
> + ret = of_property_read_u32_index(np, "opp-supported-hw", count,
> + &version);
> + if (ret) {
> + dev_warn(dev, "%s: failed to read opp-supported-hw property at index %d: %d\n",
> + __func__, count, ret);
> + return false;
> + }
> +
> + /* Both of these are bitwise masks of the versions */
> + if (!(version & dev_opp->supported_hw[count]))
> + return false;
> + }
> +
> + return true;
> +}
> +
> +/**
> * _opp_add_static_v2() - Allocate static OPPs (As per 'v2' DT bindings)
> * @dev: device for which we do this operation
> * @np: device node
> @@ -879,6 +1021,12 @@ static int _opp_add_static_v2(struct device *dev, struct device_node *np)
> goto free_opp;
> }
>
> + /* Check if the OPP supports hardware's hierarchy of versions or not */
> + if (!_opp_is_supported(dev, dev_opp, np)) {
> + dev_dbg(dev, "OPP not supported by hardware: %llu\n", rate);
> + goto free_opp;
> + }
> +
> /*
> * Rate is defined as an unsigned long in clk API, and so casting
> * explicitly to its type. Must be fixed once rate is 64 bit
> diff --git a/drivers/base/power/opp/opp.h b/drivers/base/power/opp/opp.h
> index b8880c7f8be1..70f4564a6ab9 100644
> --- a/drivers/base/power/opp/opp.h
> +++ b/drivers/base/power/opp/opp.h
> @@ -129,6 +129,8 @@ struct device_list_opp {
> * @clock_latency_ns_max: Max clock latency in nanoseconds.
> * @shared_opp: OPP is shared between multiple devices.
> * @suspend_opp: Pointer to OPP to be used during device suspend.
> + * @supported_hw: Array of version number to support.
> + * @supported_hw_count: Number of elements in supported_hw array.
> * @dentry: debugfs dentry pointer of the real device directory (not links).
> * @dentry_name: Name of the real dentry.
> *
> @@ -153,6 +155,9 @@ struct device_opp {
> bool shared_opp;
> struct dev_pm_opp *suspend_opp;
>
> + unsigned int *supported_hw;
> + unsigned int supported_hw_count;
> +
> #ifdef CONFIG_DEBUG_FS
> struct dentry *dentry;
> char dentry_name[NAME_MAX];
> diff --git a/include/linux/pm_opp.h b/include/linux/pm_opp.h
> index 9a2e50337af9..3a85110242f0 100644
> --- a/include/linux/pm_opp.h
> +++ b/include/linux/pm_opp.h
> @@ -55,6 +55,9 @@ int dev_pm_opp_enable(struct device *dev, unsigned long freq);
> int dev_pm_opp_disable(struct device *dev, unsigned long freq);
>
> struct srcu_notifier_head *dev_pm_opp_get_notifier(struct device *dev);
> +int dev_pm_opp_set_supported_hw(struct device *dev, const u32 *versions,
> + unsigned int count);
> +void dev_pm_opp_put_supported_hw(struct device *dev);
> #else
> static inline unsigned long dev_pm_opp_get_voltage(struct dev_pm_opp *opp)
> {
> @@ -129,6 +132,16 @@ static inline struct srcu_notifier_head *dev_pm_opp_get_notifier(
> {
> return ERR_PTR(-EINVAL);
> }
> +
> +static inline int dev_pm_opp_set_supported_hw(struct device *dev,
> + const u32 *versions,
> + unsigned int count)
> +{
> + return -EINVAL;
> +}
> +
> +static inline void dev_pm_opp_put_supported_hw(struct device *dev) {}
> +
> #endif /* CONFIG_PM_OPP */
>
> #if defined(CONFIG_PM_OPP) && defined(CONFIG_OF)
> --
> 2.6.2.198.g614a2ac
>
> _______________________________________________
> linaro-kernel mailing list
> linaro-kernel@...ts.linaro.org
> https://lists.linaro.org/mailman/listinfo/linaro-kernel
--
Lee Jones
Linaro ST Landing Team Lead
Linaro.org │ Open source software for ARM SoCs
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