Patchwork [PATCHv5,RFC,12/15] hwspinlock/core: add OF helper to parse reserved locks

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Submitter Anna, Suman
Date May 1, 2014, 12:34 a.m.
Message ID <1398904476-26200-13-git-send-email-s-anna@ti.com>
Download mbox | patch
Permalink /patch/344373/
State New
Headers show

Comments

Anna, Suman - May 1, 2014, 12:34 a.m.
The property 'hwlock-reserved-locks' will be used to represent
the number of locks to be reserved for clients that would need
to request/operate on specific locks. A new OF helper function,
of_hwspin_lock_get_num_reserved_locks(), is added to minimize
duplication in different platform implementations.

The function will return a value of 0 if the property is not
defined, so as to support a default behavior of marking all
locks as unused and open for anonymous allocations.

Signed-off-by: Suman Anna <s-anna@ti.com>
---
 .../devicetree/bindings/hwlock/hwlock.txt          |  3 +++
 drivers/hwspinlock/hwspinlock_core.c               | 25 ++++++++++++++++++++++
 include/linux/hwspinlock.h                         |  1 +
 3 files changed, 29 insertions(+)
Anna, Suman - May 5, 2014, 9:44 p.m.
Hi Rob,

On 04/30/2014 07:34 PM, Suman Anna wrote:
> The property 'hwlock-reserved-locks' will be used to represent
> the number of locks to be reserved for clients that would need
> to request/operate on specific locks. A new OF helper function,
> of_hwspin_lock_get_num_reserved_locks(), is added to minimize
> duplication in different platform implementations.
> 
> The function will return a value of 0 if the property is not
> defined, so as to support a default behavior of marking all
> locks as unused and open for anonymous allocations.
> 
> Signed-off-by: Suman Anna <s-anna@ti.com>
> ---
>  .../devicetree/bindings/hwlock/hwlock.txt          |  3 +++
>  drivers/hwspinlock/hwspinlock_core.c               | 25 ++++++++++++++++++++++
>  include/linux/hwspinlock.h                         |  1 +
>  3 files changed, 29 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/hwlock/hwlock.txt b/Documentation/devicetree/bindings/hwlock/hwlock.txt
> index d538a9b..88d16d2 100644
> --- a/Documentation/devicetree/bindings/hwlock/hwlock.txt
> +++ b/Documentation/devicetree/bindings/hwlock/hwlock.txt
> @@ -18,6 +18,9 @@ Common properties:
>  			property is needed on hwlock devices, where the number
>  			of supported locks within a hwlock device cannot be
>  			read from a register.
> +- hwlock-reserved-locks: Number of locks to reserve for clients requiring
> +			specific locks. This value cannot exceed the value of
> +			hwlock-num-locks.

Any suggestions here on the approach? This property falls into a gray
area as well, as the current approach is somewhat limiting (it doesn't
support sparse reserved locks, and expects them at the beginning of the
lock range).

regards
Suman

>  - hwlock-base-id:	An unique base Id for the locks for a particular hwlock
>  			device. This property is mandatory ONLY if a SoC has
>  			several hwlock devices.
> diff --git a/drivers/hwspinlock/hwspinlock_core.c b/drivers/hwspinlock/hwspinlock_core.c
> index e05cea8..e74b55b 100644
> --- a/drivers/hwspinlock/hwspinlock_core.c
> +++ b/drivers/hwspinlock/hwspinlock_core.c
> @@ -286,6 +286,31 @@ int of_hwspin_lock_get_base_id(struct device_node *dn)
>  EXPORT_SYMBOL_GPL(of_hwspin_lock_get_base_id);
>  
>  /**
> + * of_hwspin_lock_get_num_reserved_locks() - retrieve number of reserved locks
> + * @dn: device node pointer
> + *
> + * This is an OF helper function that can be called by the underlying platform
> + * specific implementations, to retrieve the number of locks to reserve from
> + * the hwspinlock device instance's base id. The hwlock-reserved-locks DT
> + * property needs to be defined for requesting any DT-based locks.
> + *
> + * Returns a positive number of locks on success, a default value of 0 if the
> + * property is missing or an appropriate error code as returned by the OF layer
> + */
> +int of_hwspin_lock_get_num_reserved_locks(struct device_node *dn)
> +{
> +	unsigned int val = 0;
> +	int ret;
> +
> +	ret = of_property_read_u32(dn, "hwlock-reserved-locks", &val);
> +	if (!ret || ret == -EINVAL)
> +		ret = val;
> +
> +	return ret;
> +}
> +EXPORT_SYMBOL_GPL(of_hwspin_lock_get_num_reserved_locks);
> +
> +/**
>   * of_hwspin_lock_get_num_locks() - OF helper to retrieve number of locks
>   * @dn: device node pointer
>   *
> diff --git a/include/linux/hwspinlock.h b/include/linux/hwspinlock.h
> index d120035..d18431f 100644
> --- a/include/linux/hwspinlock.h
> +++ b/include/linux/hwspinlock.h
> @@ -69,6 +69,7 @@ int of_hwspin_lock_simple_xlate(struct hwspinlock_device *bank,
>  				const struct of_phandle_args *hwlock_spec);
>  int of_hwspin_lock_get_base_id(struct device_node *dn);
>  int of_hwspin_lock_get_num_locks(struct device_node *dn);
> +int of_hwspin_lock_get_num_reserved_locks(struct device_node *dn);
>  int hwspin_lock_register(struct hwspinlock_device *bank, struct device *dev,
>  		const struct hwspinlock_ops *ops, int base_id, int num_locks,
>  		int num_reserved_locks);
> 

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Josh Cartwright - May 5, 2014, 9:54 p.m.
On Mon, May 05, 2014 at 04:44:25PM -0500, Suman Anna wrote:
> Hi Rob,
> 
> On 04/30/2014 07:34 PM, Suman Anna wrote:
> > The property 'hwlock-reserved-locks' will be used to represent
> > the number of locks to be reserved for clients that would need
> > to request/operate on specific locks. A new OF helper function,
> > of_hwspin_lock_get_num_reserved_locks(), is added to minimize
> > duplication in different platform implementations.
> > 
> > The function will return a value of 0 if the property is not
> > defined, so as to support a default behavior of marking all
> > locks as unused and open for anonymous allocations.
> > 
> > Signed-off-by: Suman Anna <s-anna@ti.com>
> > ---
> >  .../devicetree/bindings/hwlock/hwlock.txt          |  3 +++
> >  drivers/hwspinlock/hwspinlock_core.c               | 25 ++++++++++++++++++++++
> >  include/linux/hwspinlock.h                         |  1 +
> >  3 files changed, 29 insertions(+)
> > 
> > diff --git a/Documentation/devicetree/bindings/hwlock/hwlock.txt b/Documentation/devicetree/bindings/hwlock/hwlock.txt
> > index d538a9b..88d16d2 100644
> > --- a/Documentation/devicetree/bindings/hwlock/hwlock.txt
> > +++ b/Documentation/devicetree/bindings/hwlock/hwlock.txt
> > @@ -18,6 +18,9 @@ Common properties:
> >  			property is needed on hwlock devices, where the number
> >  			of supported locks within a hwlock device cannot be
> >  			read from a register.
> > +- hwlock-reserved-locks: Number of locks to reserve for clients requiring
> > +			specific locks. This value cannot exceed the value of
> > +			hwlock-num-locks.
> 
> Any suggestions here on the approach? This property falls into a gray
> area as well, as the current approach is somewhat limiting (it doesn't
> support sparse reserved locks, and expects them at the beginning of the
> lock range).

Is it possible to implement a pinctrl-like hogging approach, whereby the
specific locks that need to be reserved are consumed by the controller
itself?

  Josh

Patch

diff --git a/Documentation/devicetree/bindings/hwlock/hwlock.txt b/Documentation/devicetree/bindings/hwlock/hwlock.txt
index d538a9b..88d16d2 100644
--- a/Documentation/devicetree/bindings/hwlock/hwlock.txt
+++ b/Documentation/devicetree/bindings/hwlock/hwlock.txt
@@ -18,6 +18,9 @@  Common properties:
 			property is needed on hwlock devices, where the number
 			of supported locks within a hwlock device cannot be
 			read from a register.
+- hwlock-reserved-locks: Number of locks to reserve for clients requiring
+			specific locks. This value cannot exceed the value of
+			hwlock-num-locks.
 - hwlock-base-id:	An unique base Id for the locks for a particular hwlock
 			device. This property is mandatory ONLY if a SoC has
 			several hwlock devices.
diff --git a/drivers/hwspinlock/hwspinlock_core.c b/drivers/hwspinlock/hwspinlock_core.c
index e05cea8..e74b55b 100644
--- a/drivers/hwspinlock/hwspinlock_core.c
+++ b/drivers/hwspinlock/hwspinlock_core.c
@@ -286,6 +286,31 @@  int of_hwspin_lock_get_base_id(struct device_node *dn)
 EXPORT_SYMBOL_GPL(of_hwspin_lock_get_base_id);
 
 /**
+ * of_hwspin_lock_get_num_reserved_locks() - retrieve number of reserved locks
+ * @dn: device node pointer
+ *
+ * This is an OF helper function that can be called by the underlying platform
+ * specific implementations, to retrieve the number of locks to reserve from
+ * the hwspinlock device instance's base id. The hwlock-reserved-locks DT
+ * property needs to be defined for requesting any DT-based locks.
+ *
+ * Returns a positive number of locks on success, a default value of 0 if the
+ * property is missing or an appropriate error code as returned by the OF layer
+ */
+int of_hwspin_lock_get_num_reserved_locks(struct device_node *dn)
+{
+	unsigned int val = 0;
+	int ret;
+
+	ret = of_property_read_u32(dn, "hwlock-reserved-locks", &val);
+	if (!ret || ret == -EINVAL)
+		ret = val;
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(of_hwspin_lock_get_num_reserved_locks);
+
+/**
  * of_hwspin_lock_get_num_locks() - OF helper to retrieve number of locks
  * @dn: device node pointer
  *
diff --git a/include/linux/hwspinlock.h b/include/linux/hwspinlock.h
index d120035..d18431f 100644
--- a/include/linux/hwspinlock.h
+++ b/include/linux/hwspinlock.h
@@ -69,6 +69,7 @@  int of_hwspin_lock_simple_xlate(struct hwspinlock_device *bank,
 				const struct of_phandle_args *hwlock_spec);
 int of_hwspin_lock_get_base_id(struct device_node *dn);
 int of_hwspin_lock_get_num_locks(struct device_node *dn);
+int of_hwspin_lock_get_num_reserved_locks(struct device_node *dn);
 int hwspin_lock_register(struct hwspinlock_device *bank, struct device *dev,
 		const struct hwspinlock_ops *ops, int base_id, int num_locks,
 		int num_reserved_locks);