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Date: Tue, 28 Apr 2015 12:39:09 -0500
From: "J. German Rivera" <German.Rivera@...escale.com>
To: <gregkh@...uxfoundation.org>, <arnd@...db.de>,
<devel@...verdev.osuosl.org>, <linux-kernel@...r.kernel.org>
CC: <stuart.yoder@...escale.com>, <itai.katz@...escale.com>,
<scottwood@...escale.com>, <agraf@...e.de>,
<bhamciu1@...escale.com>, <R89243@...escale.com>,
<bhupesh.sharma@...escale.com>, <nir.erez@...escale.com>,
<richard.schmitt@...escale.com>,
"J. German Rivera" <German.Rivera@...escale.com>
Subject: [PATCH 6/7] staging: fsl-mc: Add locking to serialize mc_send_command() calls
Add a locking mechanism to serialize mc_send_command() calls that use
the same fsl_mc_io object (same MC portal). All mc_send_command() calls
with the same fsl_m_io object have to be either from non-atomic context
or from atomic context, but not both. When the fsl_mc_io object is
created the owner needs to know in which type of context the fsl_mc_io
object is going to be used. A flag passed-in to fsl_create_mc_io()
will indicate whether the fsl_mc_io object will be used in atomic or
non-atomic context. If the fsl_mc_io object is going to be used in
non-atomic context, mc_send_command() calls with it will be
serialized using a mutex. Otherwise, if the fsl_mc_io object is
going to be used in atomic context, mc_semd_command() calls with it
will be serialized using a spinlock.
Signed-off-by: J. German Rivera <German.Rivera@...escale.com>
Change-Id: Icb770cd36e204ee6a17ad0f81e1d31cc9fe96816
Reviewed-on: http://git.am.freescale.net:8181/34876
Tested-by: Review Code-CDREVIEW <CDREVIEW@...escale.com>
Reviewed-by: Stuart Yoder <stuart.yoder@...escale.com>
---
drivers/staging/fsl-mc/bus/mc-sys.c | 36 ++++++++++++++++++++++++++++-----
drivers/staging/fsl-mc/include/mc-sys.h | 23 +++++++++++++++++++--
2 files changed, 52 insertions(+), 7 deletions(-)
diff --git a/drivers/staging/fsl-mc/bus/mc-sys.c b/drivers/staging/fsl-mc/bus/mc-sys.c
index 9ae000c..1679054 100644
--- a/drivers/staging/fsl-mc/bus/mc-sys.c
+++ b/drivers/staging/fsl-mc/bus/mc-sys.c
@@ -86,6 +86,11 @@ int __must_check fsl_create_mc_io(struct device *dev,
mc_io->portal_phys_addr = mc_portal_phys_addr;
mc_io->portal_size = mc_portal_size;
mc_io->resource = resource;
+ if (flags & FSL_MC_IO_ATOMIC_CONTEXT_PORTAL)
+ spin_lock_init(&mc_io->spinlock);
+ else
+ mutex_init(&mc_io->mutex);
+
res = devm_request_mem_region(dev,
mc_portal_phys_addr,
mc_portal_size,
@@ -230,15 +235,26 @@ static inline enum mc_cmd_status mc_read_response(struct mc_command __iomem *
* @cmd: command to be sent
*
* Returns '0' on Success; Error code otherwise.
- *
- * NOTE: This function cannot be invoked from from atomic contexts.
*/
int mc_send_command(struct fsl_mc_io *mc_io, struct mc_command *cmd)
{
+ int error;
enum mc_cmd_status status;
unsigned long jiffies_until_timeout =
jiffies + MC_CMD_COMPLETION_TIMEOUT_JIFFIES;
+ if (preemptible()) {
+ if (WARN_ON(mc_io->flags & FSL_MC_IO_ATOMIC_CONTEXT_PORTAL))
+ return -EINVAL;
+
+ mutex_lock(&mc_io->mutex);
+ } else {
+ if (WARN_ON(!(mc_io->flags & FSL_MC_IO_ATOMIC_CONTEXT_PORTAL)))
+ return -EINVAL;
+
+ spin_lock(&mc_io->spinlock);
+ }
+
/*
* Send command to the MC hardware:
*/
@@ -269,7 +285,8 @@ int mc_send_command(struct fsl_mc_io *mc_io, struct mc_command *cmd)
(unsigned int)
MC_CMD_HDR_READ_CMDID(cmd->header));
- return -ETIMEDOUT;
+ error = -ETIMEDOUT;
+ goto common_exit;
}
}
@@ -281,9 +298,18 @@ int mc_send_command(struct fsl_mc_io *mc_io, struct mc_command *cmd)
mc_status_to_string(status),
(unsigned int)status);
- return mc_status_to_error(status);
+ error = mc_status_to_error(status);
+ goto common_exit;
}
- return 0;
+ error = 0;
+
+common_exit:
+ if (preemptible())
+ mutex_unlock(&mc_io->mutex);
+ else
+ spin_unlock(&mc_io->spinlock);
+
+ return error;
}
EXPORT_SYMBOL(mc_send_command);
diff --git a/drivers/staging/fsl-mc/include/mc-sys.h b/drivers/staging/fsl-mc/include/mc-sys.h
index cb3b5a2..24e51f7 100644
--- a/drivers/staging/fsl-mc/include/mc-sys.h
+++ b/drivers/staging/fsl-mc/include/mc-sys.h
@@ -39,6 +39,13 @@
#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
+ */
+#define FSL_MC_IO_ATOMIC_CONTEXT_PORTAL 0x0001
struct fsl_mc_resource;
struct mc_command;
@@ -53,14 +60,26 @@ struct mc_command;
* @resource: generic resource associated with the MC portal if
* the MC portal came from a resource pool, or NULL if the MC portal
* is permanently bound to a device (e.g., a DPRC)
+ * @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.
+ * @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 must be made only from atomic context.
*/
struct fsl_mc_io {
struct device *dev;
- uint32_t flags;
- uint32_t portal_size;
+ uint16_t flags;
+ uint16_t portal_size;
phys_addr_t portal_phys_addr;
void __iomem *portal_virt_addr;
struct fsl_mc_resource *resource;
+ union {
+ struct mutex mutex; /* serializes mc_send_command() calls */
+ spinlock_t spinlock; /* serializes mc_send_command() calls */
+ };
};
int __must_check fsl_create_mc_io(struct device *dev,
--
2.3.3
--
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