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Subject[PATCHv6 4/5] hwspinlock/core: add common OF helpers
Date
This patch adds three new OF helper functions to use/request
locks from a hwspinlock device instantiated through a
device-tree blob.

1. The of_hwspin_lock_get_num_locks() is a common OF helper
function to read the 'hwlock-num-locks' property.
2. The of_hwspin_lock_get_base_id() is a common OF helper
function to read the 'hwlock-base-id' property.
3. The of_hwspin_lock_get_id() API can be used by hwspinlock
clients to get the id for a specific lock using the phandle
+ args specifier, so that it can be requested using the
available hwspin_lock_request_specific() API.

Signed-off-by: Suman Anna <s-anna@ti.com>
---
Documentation/hwspinlock.txt | 26 ++++++++
drivers/hwspinlock/hwspinlock_core.c | 122 +++++++++++++++++++++++++++++++++++
include/linux/hwspinlock.h | 15 ++++-
3 files changed, 160 insertions(+), 3 deletions(-)

diff --git a/Documentation/hwspinlock.txt b/Documentation/hwspinlock.txt
index 640ae47..c15dc9f 100644
--- a/Documentation/hwspinlock.txt
+++ b/Documentation/hwspinlock.txt
@@ -48,6 +48,16 @@ independent, drivers.
ids for predefined purposes.
Should be called from a process context (might sleep).

+ int of_hwspin_lock_get_id(struct device_node *np, int index);
+ - retrieve the global lock id for an OF phandle-based specific lock.
+ This function provides a means for DT users of a hwspinlock module
+ to get the global lock id of a specific hwspinlock, so that it can
+ be requested using the normal hwspin_lock_request_specific() API.
+ The function returns a valid lock id number on success, -EPROBE_DEFER
+ if the hwspinlock device is not yet registered with the core, or other
+ error values.
+ Should be called from a process context (might sleep).
+
int hwspin_lock_free(struct hwspinlock *hwlock);
- free a previously-assigned hwspinlock; returns 0 on success, or an
appropriate error code on failure (e.g. -EINVAL if the hwspinlock
@@ -243,6 +253,22 @@ int hwspinlock_example2(void)
Returns the address of hwspinlock on success, or NULL on error (e.g.
if the hwspinlock is still in use).

+ int of_hwspin_lock_get_num_locks(struct device_node *dn);
+ - is a common OF helper function that can be used by some underlying
+ vendor-specific implementations. This can be used by implementations
+ that require and define the number of locks supported within a hwspinlock
+ bank as a device tree node property. This function should be called by
+ needed implementations before registering a hwspinlock device with the
+ core.
+
+ int of_hwspin_lock_get_base_id(struct device_node *dn);
+ - is a common OF helper function that can be used by some underlying
+ vendor-specific implementations. This can be used by implementations
+ that require and define the base index for a block of locks present
+ within a hwspinlock bank as a device tree node property. This function
+ should be called by needed implementations before registering a hwspinlock
+ device with the core.
+
5. Important structs

struct hwspinlock_device is a device which usually contains a bank
diff --git a/drivers/hwspinlock/hwspinlock_core.c b/drivers/hwspinlock/hwspinlock_core.c
index 48f7866..7d9f749 100644
--- a/drivers/hwspinlock/hwspinlock_core.c
+++ b/drivers/hwspinlock/hwspinlock_core.c
@@ -27,6 +27,7 @@
#include <linux/hwspinlock.h>
#include <linux/pm_runtime.h>
#include <linux/mutex.h>
+#include <linux/of.h>

#include "hwspinlock_internal.h"

@@ -262,6 +263,127 @@ void __hwspin_unlock(struct hwspinlock *hwlock, int mode, unsigned long *flags)
}
EXPORT_SYMBOL_GPL(__hwspin_unlock);

+/**
+ * of_hwspin_lock_simple_xlate - translate hwlock_spec to return a lock id
+ * @bank: the hwspinlock device bank
+ * @hwlock_spec: hwlock specifier as found in the device tree
+ *
+ * This is a simple translation function, suitable for hwspinlock platform
+ * drivers that only has a lock specifier length of 1.
+ *
+ * Returns a negative value on error, and a relative index of the lock within
+ * a specified bank on success.
+ */
+static int of_hwspin_lock_simple_xlate(struct hwspinlock_device *bank,
+ const struct of_phandle_args *hwlock_spec)
+{
+ /* sanity check (these shouldn't happen) */
+ if (WARN_ON(!bank->dev->of_node))
+ return -EINVAL;
+
+ if (WARN_ON(hwlock_spec->args_count != 1))
+ return -EINVAL;
+
+ return hwlock_spec->args[0];
+}
+
+/**
+ * of_hwspin_lock_get_id() - get lock id for an OF phandle-based specific lock
+ * @np: device node from which to request the specific hwlock
+ * @index: index of the hwlock in the list of values
+ *
+ * This function provides a means for DT users of the hwspinlock module to
+ * get the global lock id of a specific hwspinlock using the phandle of the
+ * hwspinlock device, so that it can be requested using the normal
+ * hwspin_lock_request_specific() API.
+ *
+ * Returns the global lock id number on success, -EPROBE_DEFER if the hwspinlock
+ * device is not yet registered, -EINVAL on invalid args specifier value or an
+ * appropriate error as returned from the OF parsing of the DT user node.
+ */
+int of_hwspin_lock_get_id(struct device_node *np, int index)
+{
+ struct hwspinlock_device *bank;
+ struct of_phandle_args args;
+ int id;
+ int ret;
+
+ ret = of_parse_phandle_with_args(np, "hwlocks", "#hwlock-cells", index,
+ &args);
+ if (ret)
+ return ret;
+
+ mutex_lock(&hwspinlock_tree_lock);
+ list_for_each_entry(bank, &hwspinlock_devices, list)
+ if (bank->dev->of_node == args.np)
+ break;
+ mutex_unlock(&hwspinlock_tree_lock);
+ if (&bank->list == &hwspinlock_devices) {
+ ret = -EPROBE_DEFER;
+ goto out;
+ }
+
+ id = of_hwspin_lock_simple_xlate(bank, &args);
+ if (id < 0 || id >= bank->num_locks) {
+ ret = -EINVAL;
+ goto out;
+ }
+ id += bank->base_id;
+
+out:
+ of_node_put(args.np);
+ return ret ? ret : id;
+}
+EXPORT_SYMBOL_GPL(of_hwspin_lock_get_id);
+
+/**
+ * of_hwspin_lock_get_base_id() - OF helper to retrieve base id
+ * @dn: device node pointer
+ *
+ * This is an OF helper function that can be called by the underlying
+ * platform-specific implementations, to retrieve the base id for the
+ * set of locks present within a hwspinlock device instance.
+ *
+ * Returns the base id value on success, or an appropriate error code
+ * as returned by the OF layer
+ */
+int of_hwspin_lock_get_base_id(struct device_node *dn)
+{
+ unsigned int val;
+ int ret;
+
+ ret = of_property_read_u32(dn, "hwlock-base-id", &val);
+ return ret ? ret : val;
+}
+EXPORT_SYMBOL_GPL(of_hwspin_lock_get_base_id);
+
+/**
+ * of_hwspin_lock_get_num_locks() - OF helper to retrieve number of 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
+ * present within a hwspinlock device instance. The hwlock-num-locks
+ * DT property may be optional for some platforms, while mandatory for
+ * some others, so this function is typically called only by needed
+ * platform-specific implementations.
+ *
+ * Returns a positive number of locks on success, -ENODEV on generic
+ * failure or an appropriate error code as returned by the OF layer
+ */
+int of_hwspin_lock_get_num_locks(struct device_node *dn)
+{
+ unsigned int val;
+ int ret = -ENODEV;
+
+ ret = of_property_read_u32(dn, "hwlock-num-locks", &val);
+ if (!ret)
+ ret = val ? val : -ENODEV;
+
+ return ret;
+}
+EXPORT_SYMBOL_GPL(of_hwspin_lock_get_num_locks);
+
static int hwspin_lock_register_single(struct hwspinlock *hwlock, int id)
{
struct hwspinlock *tmp;
diff --git a/include/linux/hwspinlock.h b/include/linux/hwspinlock.h
index 3343298..a9eeb4f 100644
--- a/include/linux/hwspinlock.h
+++ b/include/linux/hwspinlock.h
@@ -26,6 +26,7 @@
#define HWLOCK_IRQ 0x02 /* Disable interrupts, don't save state */

struct device;
+struct device_node;
struct hwspinlock;
struct hwspinlock_device;
struct hwspinlock_ops;
@@ -60,12 +61,15 @@ struct hwspinlock_pdata {

#if defined(CONFIG_HWSPINLOCK) || defined(CONFIG_HWSPINLOCK_MODULE)

+int of_hwspin_lock_get_base_id(struct device_node *dn);
+int of_hwspin_lock_get_num_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 hwspin_lock_unregister(struct hwspinlock_device *bank);
struct hwspinlock *hwspin_lock_request(void);
struct hwspinlock *hwspin_lock_request_specific(unsigned int id);
int hwspin_lock_free(struct hwspinlock *hwlock);
+int of_hwspin_lock_get_id(struct device_node *np, int index);
int hwspin_lock_get_id(struct hwspinlock *hwlock);
int __hwspin_lock_timeout(struct hwspinlock *, unsigned int, int,
unsigned long *);
@@ -80,9 +84,9 @@ void __hwspin_unlock(struct hwspinlock *, int, unsigned long *);
* code path get compiled away. This way, if CONFIG_HWSPINLOCK is not
* required on a given setup, users will still work.
*
- * The only exception is hwspin_lock_register/hwspin_lock_unregister, with which
- * we _do_ want users to fail (no point in registering hwspinlock instances if
- * the framework is not available).
+ * The only exception is hwspin_lock_register/hwspin_lock_unregister and
+ * associated OF helpers, with which we _do_ want users to fail (no point
+ * in registering hwspinlock instances if the framework is not available).
*
* Note: ERR_PTR(-ENODEV) will still be considered a success for NULL-checking
* users. Others, which care, can still check this with IS_ERR.
@@ -120,6 +124,11 @@ void __hwspin_unlock(struct hwspinlock *hwlock, int mode, unsigned long *flags)
{
}

+static inline int of_hwspin_lock_get_id(struct device_node *np, int index)
+{
+ return 0;
+}
+
static inline int hwspin_lock_get_id(struct hwspinlock *hwlock)
{
return 0;
--
2.0.4


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