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.riv...@freescale.com> Change-Id: Icb770cd36e204ee6a17ad0f81e1d31cc9fe96816 Reviewed-on: http://git.am.freescale.net:8181/34876 Tested-by: Review Code-CDREVIEW <cdrev...@freescale.com> Reviewed-by: Stuart Yoder <stuart.yo...@freescale.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 _______________________________________________ devel mailing list de...@linuxdriverproject.org http://driverdev.linuxdriverproject.org/mailman/listinfo/driverdev-devel
