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path: root/drivers/dma/hsu/hsu.c
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Diffstat (limited to 'drivers/dma/hsu/hsu.c')
-rw-r--r--drivers/dma/hsu/hsu.c90
1 files changed, 69 insertions, 21 deletions
diff --git a/drivers/dma/hsu/hsu.c b/drivers/dma/hsu/hsu.c
index f8c5cd53307c..c5f21efd6090 100644
--- a/drivers/dma/hsu/hsu.c
+++ b/drivers/dma/hsu/hsu.c
@@ -126,28 +126,33 @@ static void hsu_dma_start_transfer(struct hsu_dma_chan *hsuc)
hsu_dma_start_channel(hsuc);
}
-static u32 hsu_dma_chan_get_sr(struct hsu_dma_chan *hsuc)
-{
- unsigned long flags;
- u32 sr;
-
- spin_lock_irqsave(&hsuc->vchan.lock, flags);
- sr = hsu_chan_readl(hsuc, HSU_CH_SR);
- spin_unlock_irqrestore(&hsuc->vchan.lock, flags);
-
- return sr & ~(HSU_CH_SR_DESCE_ANY | HSU_CH_SR_CDESC_ANY);
-}
-
-irqreturn_t hsu_dma_irq(struct hsu_dma_chip *chip, unsigned short nr)
+/*
+ * hsu_dma_get_status() - get DMA channel status
+ * @chip: HSUART DMA chip
+ * @nr: DMA channel number
+ * @status: pointer for DMA Channel Status Register value
+ *
+ * Description:
+ * The function reads and clears the DMA Channel Status Register, checks
+ * if it was a timeout interrupt and returns a corresponding value.
+ *
+ * Caller should provide a valid pointer for the DMA Channel Status
+ * Register value that will be returned in @status.
+ *
+ * Return:
+ * 1 for DMA timeout status, 0 for other DMA status, or error code for
+ * invalid parameters or no interrupt pending.
+ */
+int hsu_dma_get_status(struct hsu_dma_chip *chip, unsigned short nr,
+ u32 *status)
{
struct hsu_dma_chan *hsuc;
- struct hsu_dma_desc *desc;
unsigned long flags;
u32 sr;
/* Sanity check */
if (nr >= chip->hsu->nr_channels)
- return IRQ_NONE;
+ return -EINVAL;
hsuc = &chip->hsu->chan[nr];
@@ -155,22 +160,65 @@ irqreturn_t hsu_dma_irq(struct hsu_dma_chip *chip, unsigned short nr)
* No matter what situation, need read clear the IRQ status
* There is a bug, see Errata 5, HSD 2900918
*/
- sr = hsu_dma_chan_get_sr(hsuc);
+ spin_lock_irqsave(&hsuc->vchan.lock, flags);
+ sr = hsu_chan_readl(hsuc, HSU_CH_SR);
+ spin_unlock_irqrestore(&hsuc->vchan.lock, flags);
+
+ /* Check if any interrupt is pending */
+ sr &= ~(HSU_CH_SR_DESCE_ANY | HSU_CH_SR_CDESC_ANY);
if (!sr)
- return IRQ_NONE;
+ return -EIO;
/* Timeout IRQ, need wait some time, see Errata 2 */
if (sr & HSU_CH_SR_DESCTO_ANY)
udelay(2);
+ /*
+ * At this point, at least one of Descriptor Time Out, Channel Error
+ * or Descriptor Done bits must be set. Clear the Descriptor Time Out
+ * bits and if sr is still non-zero, it must be channel error or
+ * descriptor done which are higher priority than timeout and handled
+ * in hsu_dma_do_irq(). Else, it must be a timeout.
+ */
sr &= ~HSU_CH_SR_DESCTO_ANY;
- if (!sr)
- return IRQ_HANDLED;
+
+ *status = sr;
+
+ return sr ? 0 : 1;
+}
+EXPORT_SYMBOL_GPL(hsu_dma_get_status);
+
+/*
+ * hsu_dma_do_irq() - DMA interrupt handler
+ * @chip: HSUART DMA chip
+ * @nr: DMA channel number
+ * @status: Channel Status Register value
+ *
+ * Description:
+ * This function handles Channel Error and Descriptor Done interrupts.
+ * This function should be called after determining that the DMA interrupt
+ * is not a normal timeout interrupt, ie. hsu_dma_get_status() returned 0.
+ *
+ * Return:
+ * IRQ_NONE for invalid channel number, IRQ_HANDLED otherwise.
+ */
+irqreturn_t hsu_dma_do_irq(struct hsu_dma_chip *chip, unsigned short nr,
+ u32 status)
+{
+ struct hsu_dma_chan *hsuc;
+ struct hsu_dma_desc *desc;
+ unsigned long flags;
+
+ /* Sanity check */
+ if (nr >= chip->hsu->nr_channels)
+ return IRQ_NONE;
+
+ hsuc = &chip->hsu->chan[nr];
spin_lock_irqsave(&hsuc->vchan.lock, flags);
desc = hsuc->desc;
if (desc) {
- if (sr & HSU_CH_SR_CHE) {
+ if (status & HSU_CH_SR_CHE) {
desc->status = DMA_ERROR;
} else if (desc->active < desc->nents) {
hsu_dma_start_channel(hsuc);
@@ -184,7 +232,7 @@ irqreturn_t hsu_dma_irq(struct hsu_dma_chip *chip, unsigned short nr)
return IRQ_HANDLED;
}
-EXPORT_SYMBOL_GPL(hsu_dma_irq);
+EXPORT_SYMBOL_GPL(hsu_dma_do_irq);
static struct hsu_dma_desc *hsu_dma_alloc_desc(unsigned int nents)
{