3 files changed, 96 insertions, 0 deletions

diff --git a/Documentation/hwspinlock.txt b/Documentation/hwspinlock.txt
index 62f7d4ea6e26..61c1ee98e59f 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 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
diff --git a/drivers/hwspinlock/hwspinlock_core.c b/drivers/hwspinlock/hwspinlock_core.c
index 461a0d739d75..52f708bcf77f 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"
 
@@ -257,6 +258,84 @@ 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 relative index of the lock within a specified bank on success,
+ * or -EINVAL on invalid specifier cell count.
+ */
+static inline int
+of_hwspin_lock_simple_xlate(const struct of_phandle_args *hwlock_spec)
+{
+        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 client node.
+ */
+int of_hwspin_lock_get_id(struct device_node *np, int index)
+{
+        struct of_phandle_args args;
+        struct hwspinlock *hwlock;
+        struct radix_tree_iter iter;
+        void **slot;
+        int id;
+        int ret;
+
+        ret = of_parse_phandle_with_args(np, "hwlocks", "#hwlock-cells", index,
+                                         &args);
+        if (ret)
+                return ret;
+
+        /* Find the hwspinlock device: we need its base_id */
+        ret = -EPROBE_DEFER;
+        rcu_read_lock();
+        radix_tree_for_each_slot(slot, &hwspinlock_tree, &iter, 0) {
+                hwlock = radix_tree_deref_slot(slot);
+                if (unlikely(!hwlock))
+                        continue;
+
+                if (hwlock->bank->dev->of_node == args.np) {
+                        ret = 0;
+                        break;
+                }
+        }
+        rcu_read_unlock();
+        if (ret < 0)
+                goto out;
+
+        id = of_hwspin_lock_simple_xlate(&args);
+        if (id < 0 || id >= hwlock->bank->num_locks) {
+                ret = -EINVAL;
+                goto out;
+        }
+        id += hwlock->bank->base_id;
+
+out:
+        of_node_put(args.np);
+        return ret ? ret : id;
+}
+EXPORT_SYMBOL_GPL(of_hwspin_lock_get_id);
+
 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 3343298e40e8..859d673d98c8 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;
@@ -66,6 +67,7 @@ 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 *);
@@ -120,6 +122,11 @@ 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;