diff options
| -rw-r--r-- | drivers/misc/carma/carma-fpga.c | 101 |
1 files changed, 61 insertions, 40 deletions
diff --git a/drivers/misc/carma/carma-fpga.c b/drivers/misc/carma/carma-fpga.c index 4fd896deda0..0cfc5bf13fa 100644 --- a/drivers/misc/carma/carma-fpga.c +++ b/drivers/misc/carma/carma-fpga.c @@ -560,6 +560,9 @@ static void data_enable_interrupts(struct fpga_device *priv) /* flush the writes */ fpga_read_reg(priv, 0, MMAP_REG_STATUS); + fpga_read_reg(priv, 1, MMAP_REG_STATUS); + fpga_read_reg(priv, 2, MMAP_REG_STATUS); + fpga_read_reg(priv, 3, MMAP_REG_STATUS); /* switch back to the external interrupt source */ iowrite32be(0x3F, priv->regs + SYS_IRQ_SOURCE_CTL); @@ -591,8 +594,12 @@ static void data_dma_cb(void *data) list_move_tail(&priv->inflight->entry, &priv->used); priv->inflight = NULL; - /* clear the FPGA status and re-enable interrupts */ - data_enable_interrupts(priv); + /* + * If data dumping is still enabled, then clear the FPGA + * status registers and re-enable FPGA interrupts + */ + if (priv->enabled) + data_enable_interrupts(priv); spin_unlock_irqrestore(&priv->lock, flags); @@ -708,6 +715,15 @@ static irqreturn_t data_irq(int irq, void *dev_id) spin_lock(&priv->lock); + /* + * This is an error case that should never happen. + * + * If this driver has a bug and manages to re-enable interrupts while + * a DMA is in progress, then we will hit this statement and should + * start paying attention immediately. + */ + BUG_ON(priv->inflight != NULL); + /* hide the interrupt by switching the IRQ driver to GPIO */ data_disable_interrupts(priv); @@ -762,11 +778,15 @@ out: */ static int data_device_enable(struct fpga_device *priv) { + bool enabled; u32 val; int ret; /* multiple enables are safe: they do nothing */ - if (priv->enabled) + spin_lock_irq(&priv->lock); + enabled = priv->enabled; + spin_unlock_irq(&priv->lock); + if (enabled) return 0; /* check that the FPGAs are programmed */ @@ -797,6 +817,9 @@ static int data_device_enable(struct fpga_device *priv) goto out_error; } + /* prevent the FPGAs from generating interrupts */ + data_disable_interrupts(priv); + /* hookup the irq handler */ ret = request_irq(priv->irq, data_irq, IRQF_SHARED, drv_name, priv); if (ret) { @@ -804,11 +827,13 @@ static int data_device_enable(struct fpga_device *priv) goto out_error; } - /* switch to the external FPGA IRQ line */ - data_enable_interrupts(priv); - - /* success, we're enabled */ + /* allow the DMA callback to re-enable FPGA interrupts */ + spin_lock_irq(&priv->lock); priv->enabled = true; + spin_unlock_irq(&priv->lock); + + /* allow the FPGAs to generate interrupts */ + data_enable_interrupts(priv); return 0; out_error: @@ -834,41 +859,40 @@ out_error: */ static int data_device_disable(struct fpga_device *priv) { - int ret; + spin_lock_irq(&priv->lock); /* allow multiple disable */ - if (!priv->enabled) + if (!priv->enabled) { + spin_unlock_irq(&priv->lock); return 0; + } + + /* + * Mark the device disabled + * + * This stops DMA callbacks from re-enabling interrupts + */ + priv->enabled = false; - /* switch to the internal GPIO IRQ line */ + /* prevent the FPGAs from generating interrupts */ data_disable_interrupts(priv); + /* wait until all ongoing DMA has finished */ + while (priv->inflight != NULL) { + spin_unlock_irq(&priv->lock); + wait_event(priv->wait, priv->inflight == NULL); + spin_lock_irq(&priv->lock); + } + + spin_unlock_irq(&priv->lock); + /* unhook the irq handler */ free_irq(priv->irq, priv); - /* - * wait for all outstanding DMA to complete - * - * Device interrupts are disabled, therefore another buffer cannot - * be marked inflight. - */ - ret = wait_event_interruptible(priv->wait, priv->inflight == NULL); - if (ret) - return ret; - /* free the correlation table */ sg_free_table(&priv->corl_table); priv->corl_nents = 0; - /* - * We are taking the spinlock not to protect priv->enabled, but instead - * to make sure that there are no readers in the process of altering - * the free or used lists while we are setting this flag. - */ - spin_lock_irq(&priv->lock); - priv->enabled = false; - spin_unlock_irq(&priv->lock); - /* free all buffers: the free and used lists are not being changed */ data_free_buffers(priv); return 0; @@ -896,15 +920,6 @@ static unsigned int list_num_entries(struct list_head *list) static int data_debug_show(struct seq_file *f, void *offset) { struct fpga_device *priv = f->private; - int ret; - - /* - * Lock the mutex first, so that we get an accurate value for enable - * Lock the spinlock next, to get accurate list counts - */ - ret = mutex_lock_interruptible(&priv->mutex); - if (ret) - return ret; spin_lock_irq(&priv->lock); @@ -917,7 +932,6 @@ static int data_debug_show(struct seq_file *f, void *offset) seq_printf(f, "num_dropped: %d\n", priv->num_dropped); spin_unlock_irq(&priv->lock); - mutex_unlock(&priv->mutex); return 0; } @@ -970,7 +984,13 @@ static ssize_t data_en_show(struct device *dev, struct device_attribute *attr, char *buf) { struct fpga_device *priv = dev_get_drvdata(dev); - return snprintf(buf, PAGE_SIZE, "%u\n", priv->enabled); + int ret; + + spin_lock_irq(&priv->lock); + ret = snprintf(buf, PAGE_SIZE, "%u\n", priv->enabled); + spin_unlock_irq(&priv->lock); + + return ret; } static ssize_t data_en_set(struct device *dev, struct device_attribute *attr, @@ -986,6 +1006,7 @@ static ssize_t data_en_set(struct device *dev, struct device_attribute *attr, return -EINVAL; } + /* protect against concurrent enable/disable */ ret = mutex_lock_interruptible(&priv->mutex); if (ret) return ret; |