Messages in this thread Patch in this message | | | From | Bryan Wu <> | Subject | [PATCH 2/2] Blackfin SPI Driver: implement spi_lock_bus(), spi_unlock_bus() in blackfin spi controller driver. | Date | Tue, 18 Nov 2008 15:57:47 +0800 |
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From: Yi Li <yi.li@analog.com>
Signed-off-by: Yi Li <yi.li@analog.com> Signed-off-by: Bryan Wu <cooloney@kernel.org> --- drivers/spi/spi_bfin5xx.c | 81 +++++++++++++++++++++++++++++++++++++++++++-- 1 files changed, 78 insertions(+), 3 deletions(-)
diff --git a/drivers/spi/spi_bfin5xx.c b/drivers/spi/spi_bfin5xx.c index 0e3102a..28dd0fe 100644 --- a/drivers/spi/spi_bfin5xx.c +++ b/drivers/spi/spi_bfin5xx.c @@ -45,6 +45,8 @@ MODULE_LICENSE("GPL"); #define QUEUE_RUNNING 0 #define QUEUE_STOPPED 1 +#define BFIN_SPI_LOCK 1 + struct driver_data { /* Driver model hookup */ struct platform_device *pdev; @@ -68,7 +70,10 @@ struct driver_data { struct list_head queue; int busy; int run; - +#ifdef BFIN_SPI_LOCK + /* SPI bus is lock by a slave for exclusive access */ + int locked; +#endif /* Message Transfer pump */ struct tasklet_struct pump_transfers; @@ -932,6 +937,10 @@ static void pump_messages(struct work_struct *work) { struct driver_data *drv_data; unsigned long flags; +#ifdef BFIN_SPI_LOCK + int locked_cs = -1; + struct spi_message *next_msg = NULL, *msg = NULL; +#endif drv_data = container_of(work, struct driver_data, pump_messages); @@ -950,10 +959,35 @@ static void pump_messages(struct work_struct *work) return; } +#ifdef BFIN_SPI_LOCK + /* Extract head of queue */ + next_msg = list_entry(drv_data->queue.next, + struct spi_message, queue); + + if (drv_data->locked) + locked_cs = drv_data->locked; + + /* Someone has locked the bus */ + if (drv_data->locked && next_msg->spi->chip_select != locked_cs) { + list_for_each_entry(msg, &drv_data->queue, queue) { + if (msg->spi->chip_select == locked_cs) { + next_msg = msg; + break; + } + } + /* Do nothing even if there are messages for other devices */ + if (next_msg->spi->chip_select != locked_cs) { + drv_data->busy = 0; + spin_unlock_irqrestore(&drv_data->lock, flags); + return; + } + } + drv_data->cur_msg = next_msg; +#else /* Extract head of queue */ drv_data->cur_msg = list_entry(drv_data->queue.next, - struct spi_message, queue); - + struct spi_message, queue); +#endif /* Setup the SSP using the per chip configuration */ drv_data->cur_chip = spi_get_ctldata(drv_data->cur_msg->spi); restore_state(drv_data); @@ -982,6 +1016,39 @@ static void pump_messages(struct work_struct *work) } /* + * lock the spi bus for exclusive access + */ +static int lock_bus(struct spi_device *spi) +{ +#ifdef BFIN_SPI_LOCK + struct driver_data *drv_data = spi_master_get_devdata(spi->master); + unsigned long flags; + + spin_lock_irqsave(&drv_data->lock, flags); + if (drv_data->locked) { + spin_unlock_irqrestore(&drv_data->lock, flags); + return -ENOLCK; + } + drv_data->locked = spi->chip_select; + spin_unlock_irqrestore(&drv_data->lock, flags); +#endif + return 0; +} + +static int unlock_bus(struct spi_device *spi) +{ +#ifdef BFIN_SPI_LOCK + struct driver_data *drv_data = spi_master_get_devdata(spi->master); + unsigned long flags; + + spin_lock_irqsave(&drv_data->lock, flags); + drv_data->locked = 0; + spin_unlock_irqrestore(&drv_data->lock, flags); +#endif + return 0; +} + +/* * got a msg to transfer, queue it in drv_data->queue. * And kick off message pumper */ @@ -1188,6 +1255,9 @@ static inline int init_queue(struct driver_data *drv_data) INIT_LIST_HEAD(&drv_data->queue); spin_lock_init(&drv_data->lock); +#ifdef BFIN_SPI_LOCK + drv_data->locked = 0; +#endif drv_data->run = QUEUE_STOPPED; drv_data->busy = 0; @@ -1235,6 +1305,9 @@ static inline int stop_queue(struct driver_data *drv_data) spin_lock_irqsave(&drv_data->lock, flags); +#ifdef BFIN_SPI_LOCK + drv_data->locked = 0; +#endif /* * This is a bit lame, but is optimized for the common execution path. * A wait_queue on the drv_data->busy could be used, but then the common @@ -1298,6 +1371,8 @@ static int __init bfin5xx_spi_probe(struct platform_device *pdev) master->cleanup = cleanup; master->setup = setup; master->transfer = transfer; + master->lock_bus = lock_bus; + master->unlock_bus = unlock_bus; /* Find and map our resources */ res = platform_get_resource(pdev, IORESOURCE_MEM, 0); -- 1.5.6.3
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