staging: fsl-mc: Added serialization to mc_send_command()

When the same portal is used to call mc_send_command() from two
different threads or a thread and an interrupt handler, serialization
is required, as the MC only supports one outstanding command per MC
portal. Thus, a new command should not be sent to the MC until the
last command sent has been responded by the MC.

Signed-off-by: J. German Rivera <German.Rivera@freescale.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 29 insertions, 0 deletions

diff --git a/drivers/staging/fsl-mc/include/mc-sys.h b/drivers/staging/fsl-mc/include/mc-sys.h
index 15e19af31115..c5038cc77240 100644
--- a/drivers/staging/fsl-mc/include/mc-sys.h
+++ b/drivers/staging/fsl-mc/include/mc-sys.h
@@ -39,6 +39,8 @@
 #include <linux/errno.h>
 #include <linux/io.h>
 #include <linux/dma-mapping.h>
+#include <linux/mutex.h>
+#include <linux/spinlock.h>
 
 /**
  * Bit masks for a MC I/O object (struct fsl_mc_io) flags
@@ -56,6 +58,20 @@ struct mc_command;
  * @portal_phys_addr: MC command portal physical address
  * @portal_virt_addr: MC command portal virtual address
  * @dpmcp_dev: pointer to the DPMCP device associated with the MC portal.
+ *
+ * Fields are only meaningful if the FSL_MC_IO_ATOMIC_CONTEXT_PORTAL flag is not
+ * set:
+ * @mutex: Mutex to serialize mc_send_command() calls that use the same MC
+ * portal, if the fsl_mc_io object was created with the
+ * FSL_MC_IO_ATOMIC_CONTEXT_PORTAL flag off. mc_send_command() calls for this
+ * fsl_mc_io object must be made only from non-atomic context.
+ *
+ * Fields are only meaningful if the FSL_MC_IO_ATOMIC_CONTEXT_PORTAL flag is
+ * set:
+ * @spinlock: Spinlock to serialize mc_send_command() calls that use the same MC
+ * portal, if the fsl_mc_io object was created with the
+ * FSL_MC_IO_ATOMIC_CONTEXT_PORTAL flag on. mc_send_command() calls for this
+ * fsl_mc_io object can be made from atomic or non-atomic context.
  */
 struct fsl_mc_io {
 	struct device *dev;
@@ -64,6 +80,19 @@ struct fsl_mc_io {
 	phys_addr_t portal_phys_addr;
 	void __iomem *portal_virt_addr;
 	struct fsl_mc_device *dpmcp_dev;
+	union {
+		/*
+		 * This field is only meaningful if the
+		 * FSL_MC_IO_ATOMIC_CONTEXT_PORTAL flag is not set
+		 */
+		struct mutex mutex; /* serializes mc_send_command() */
+
+		/*
+		 * This field is only meaningful if the
+		 * FSL_MC_IO_ATOMIC_CONTEXT_PORTAL flag is set
+		 */
+		spinlock_t spinlock;	/* serializes mc_send_command() */
+	};
 };
 
 int __must_check fsl_create_mc_io(struct device *dev,