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Subject[PATCHv6 3/5] hwspinlock/core: maintain a list of registered hwspinlock banks
Date
The hwspinlock_device structure is used for registering a bank of
locks with the driver core. The structure already contains the
necessary members to identify the bank of locks. The core does not
maintain the hwspinlock_devices itself, but maintains only a radix
tree for all the registered locks. A specific lock can be requested
by users using a global lock id, and any device-specific fields
can be retrieved through a reference to the hwspinlock_device in
each lock.

The global lock id, however, is not friendly to be requested for
users using the device-tree model. The device-tree representation
will typically have each of the hwspinlock devices represented as
a DT node, and a specific lock can be requested using the device's
phandle and a lock specifier. Add support to the core therefore to
maintain all the registered hwspinlock_devices, so that a device
can be looked up and a specific lock belonging to the device
requested through a phandle + args approach.

Signed-off-by: Suman Anna <s-anna@ti.com>
---
Documentation/hwspinlock.txt | 2 ++
drivers/hwspinlock/hwspinlock_core.c | 51 ++++++++++++++++++++++++++++++++
drivers/hwspinlock/hwspinlock_internal.h | 2 ++
3 files changed, 55 insertions(+)

diff --git a/Documentation/hwspinlock.txt b/Documentation/hwspinlock.txt
index 62f7d4e..640ae47 100644
--- a/Documentation/hwspinlock.txt
+++ b/Documentation/hwspinlock.txt
@@ -251,6 +251,7 @@ implementation using the hwspin_lock_register() API.

/**
* struct hwspinlock_device - a device which usually spans numerous hwspinlocks
+ * @list: list element to link hwspinlock devices together
* @dev: underlying device, will be used to invoke runtime PM api
* @ops: platform-specific hwspinlock handlers
* @base_id: id index of the first lock in this device
@@ -258,6 +259,7 @@ implementation using the hwspin_lock_register() API.
* @lock: dynamically allocated array of 'struct hwspinlock'
*/
struct hwspinlock_device {
+ struct list_head list;
struct device *dev;
const struct hwspinlock_ops *ops;
int base_id;
diff --git a/drivers/hwspinlock/hwspinlock_core.c b/drivers/hwspinlock/hwspinlock_core.c
index 461a0d7..48f7866 100644
--- a/drivers/hwspinlock/hwspinlock_core.c
+++ b/drivers/hwspinlock/hwspinlock_core.c
@@ -59,6 +59,11 @@ static RADIX_TREE(hwspinlock_tree, GFP_KERNEL);
*/
static DEFINE_MUTEX(hwspinlock_tree_lock);

+/*
+ * A linked list for maintaining all the registered hwspinlock devices.
+ * The list is maintained in an ordered-list of the supported locks group.
+ */
+static LIST_HEAD(hwspinlock_devices);

/**
* __hwspin_trylock() - attempt to lock a specific hwspinlock
@@ -307,6 +312,40 @@ out:
return hwlock;
}

+/*
+ * Add a new hwspinlock device to the global list, keeping the list of
+ * devices sorted by base order.
+ *
+ * Returns 0 on success, or -EBUSY if the new device overlaps with some
+ * other device's lock space.
+ */
+static int hwspinlock_device_add(struct hwspinlock_device *bank)
+{
+ struct list_head *entry = &hwspinlock_devices;
+ struct hwspinlock_device *_bank;
+ int ret = 0;
+
+ list_for_each(entry, &hwspinlock_devices) {
+ _bank = list_entry(entry, struct hwspinlock_device, list);
+ if (_bank->base_id >= bank->base_id + bank->num_locks)
+ break;
+ }
+
+ if (entry != &hwspinlock_devices &&
+ entry->prev != &hwspinlock_devices) {
+ _bank = list_entry(entry->prev, struct hwspinlock_device, list);
+ if (_bank->base_id + _bank->num_locks > bank->base_id) {
+ dev_err(bank->dev, "hwlock space overlap, cannot add device\n");
+ ret = -EBUSY;
+ }
+ }
+
+ if (!ret)
+ list_add_tail(&bank->list, entry);
+
+ return ret;
+}
+
/**
* hwspin_lock_register() - register a new hw spinlock device
* @bank: the hwspinlock device, which usually provides numerous hw locks
@@ -339,6 +378,12 @@ int hwspin_lock_register(struct hwspinlock_device *bank, struct device *dev,
bank->base_id = base_id;
bank->num_locks = num_locks;

+ mutex_lock(&hwspinlock_tree_lock);
+ ret = hwspinlock_device_add(bank);
+ mutex_unlock(&hwspinlock_tree_lock);
+ if (ret)
+ return ret;
+
for (i = 0; i < num_locks; i++) {
hwlock = &bank->lock[i];

@@ -355,6 +400,9 @@ int hwspin_lock_register(struct hwspinlock_device *bank, struct device *dev,
reg_failed:
while (--i >= 0)
hwspin_lock_unregister_single(base_id + i);
+ mutex_lock(&hwspinlock_tree_lock);
+ list_del(&bank->list);
+ mutex_unlock(&hwspinlock_tree_lock);
return ret;
}
EXPORT_SYMBOL_GPL(hwspin_lock_register);
@@ -386,6 +434,9 @@ int hwspin_lock_unregister(struct hwspinlock_device *bank)
WARN_ON(tmp != hwlock);
}

+ mutex_lock(&hwspinlock_tree_lock);
+ list_del(&bank->list);
+ mutex_unlock(&hwspinlock_tree_lock);
return 0;
}
EXPORT_SYMBOL_GPL(hwspin_lock_unregister);
diff --git a/drivers/hwspinlock/hwspinlock_internal.h b/drivers/hwspinlock/hwspinlock_internal.h
index d26f78b..aff560c 100644
--- a/drivers/hwspinlock/hwspinlock_internal.h
+++ b/drivers/hwspinlock/hwspinlock_internal.h
@@ -53,6 +53,7 @@ struct hwspinlock {

/**
* struct hwspinlock_device - a device which usually spans numerous hwspinlocks
+ * @list: list element to link hwspinlock devices together
* @dev: underlying device, will be used to invoke runtime PM api
* @ops: platform-specific hwspinlock handlers
* @base_id: id index of the first lock in this device
@@ -60,6 +61,7 @@ struct hwspinlock {
* @lock: dynamically allocated array of 'struct hwspinlock'
*/
struct hwspinlock_device {
+ struct list_head list;
struct device *dev;
const struct hwspinlock_ops *ops;
int base_id;
--
2.0.4


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