[PATCH V2 1/2] powerpc/powernv: Get a unique token for async completions

[Shilpasri G Bhat]

This patch adds support to get a unique token for async completion
requests. This will be used for creating non-repititive request
handles for consecutive requests in OPAL-OCC command/response
interface.

Signed-off-by: Shilpasri G Bhat <shilpa.b...@linux.vnet.ibm.com>
---
No changes from V1

 arch/powerpc/include/asm/opal.h             |  1 +
 arch/powerpc/platforms/powernv/opal-async.c | 46 +++++++++++++++++++++++++++++
 2 files changed, 47 insertions(+)

diff --git a/arch/powerpc/include/asm/opal.h b/arch/powerpc/include/asm/opal.h
index 588fb1c..03ed493 100644
--- a/arch/powerpc/include/asm/opal.h
+++ b/arch/powerpc/include/asm/opal.h
@@ -293,6 +293,7 @@ extern int opal_message_notifier_unregister(enum 
opal_msg_type msg_type,
 
 extern int __opal_async_get_token(void);
 extern int opal_async_get_token_interruptible(void);
+extern int opal_async_get_unique_token_interruptible(int last_token);
 extern int __opal_async_release_token(int token);
 extern int opal_async_release_token(int token);
 extern int opal_async_wait_response(uint64_t token, struct opal_msg *msg);
diff --git a/arch/powerpc/platforms/powernv/opal-async.c 
b/arch/powerpc/platforms/powernv/opal-async.c
index 83bebee..8caeea2 100644
--- a/arch/powerpc/platforms/powernv/opal-async.c
+++ b/arch/powerpc/platforms/powernv/opal-async.c
@@ -73,6 +73,52 @@ int opal_async_get_token_interruptible(void)
 }
 EXPORT_SYMBOL_GPL(opal_async_get_token_interruptible);
 
+static int __opal_async_get_new_token(int last_token)
+{
+       unsigned long flags;
+       int token;
+
+       spin_lock_irqsave(&opal_async_comp_lock, flags);
+       token = find_next_bit(opal_async_complete_map, opal_max_async_tokens,
+                             last_token + 1);
+       if (token >= opal_max_async_tokens) {
+               token = find_first_bit(opal_async_complete_map,
+                                      opal_max_async_tokens);
+               if (token >= opal_max_async_tokens || token == last_token) {
+                       token = -EBUSY;
+                       goto out;
+               }
+       }
+
+       pr_debug("%s token = %d\n", __func__, token);
+       if (__test_and_set_bit(token, opal_async_token_map)) {
+               token = -EBUSY;
+               goto out;
+       }
+
+       __clear_bit(token, opal_async_complete_map);
+
+out:
+       spin_unlock_irqrestore(&opal_async_comp_lock, flags);
+       return token;
+}
+
+int opal_async_get_unique_token_interruptible(int last_token)
+{
+       int token;
+
+       /* Wait until a token is available */
+       if (down_interruptible(&opal_async_sem))
+               return -ERESTARTSYS;
+
+       token = __opal_async_get_new_token(last_token);
+       if (token < 0)
+               up(&opal_async_sem);
+
+       return token;
+}
+EXPORT_SYMBOL_GPL(opal_async_get_unique_token_interruptible);
+
 int __opal_async_release_token(int token)
 {
        unsigned long flags;
-- 
1.8.3.1