Merge branch 'for-4.8/core' of git://git.kernel.dk/linux-block

[karo-tx-linux.git] / drivers / dma / hsu / hsu.c

diff --git a/drivers/dma/hsu/hsu.c b/drivers/dma/hsu/hsu.c
index f8c5cd53307c2c5993add0114720bd8b005e4f21..c5f21efd6090ee35b2cbad7e4ceeb59a391ecc8a 100644 (file)
--- 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)
 {