2 files changed, 115 insertions, 76 deletions

diff --git a/drivers/dma/at_hdmac.c b/drivers/dma/at_hdmac.c
index 1e1a4c567542..0b4fc6fb48ce 100644
--- a/drivers/dma/at_hdmac.c
+++ b/drivers/dma/at_hdmac.c
@@ -238,93 +238,126 @@ static void atc_dostart(struct at_dma_chan *atchan, struct at_desc *first)
 }
 
 /*
- * atc_get_current_descriptors -
- * locate the descriptor which equal to physical address in DSCR
- * @atchan: the channel we want to start
- * @dscr_addr: physical descriptor address in DSCR
+ * atc_get_desc_by_cookie - get the descriptor of a cookie
+ * @atchan: the DMA channel
+ * @cookie: the cookie to get the descriptor for
  */
-static struct at_desc *atc_get_current_descriptors(struct at_dma_chan *atchan,
-                                                        u32 dscr_addr)
+static struct at_desc *atc_get_desc_by_cookie(struct at_dma_chan *atchan,
+                                                dma_cookie_t cookie)
 {
-        struct at_desc  *desc, *_desc, *child, *desc_cur = NULL;
+        struct at_desc *desc, *_desc;
 
-        list_for_each_entry_safe(desc, _desc, &atchan->active_list, desc_node) {
-                if (desc->lli.dscr == dscr_addr) {
-                        desc_cur = desc;
-                        break;
-                }
+        list_for_each_entry_safe(desc, _desc, &atchan->queue, desc_node) {
+                if (desc->txd.cookie == cookie)
+                        return desc;
+        }
 
-                list_for_each_entry(child, &desc->tx_list, desc_node) {
-                        if (child->lli.dscr == dscr_addr) {
-                                desc_cur = child;
-                                break;
-                        }
-                }
+        list_for_each_entry_safe(desc, _desc, &atchan->active_list, desc_node) {
+                if (desc->txd.cookie == cookie)
+                        return desc;
         }
 
-        return desc_cur;
+        return NULL;
 }
 
-/*
- * atc_get_bytes_left -
- * Get the number of bytes residue in dma buffer,
- * @chan: the channel we want to start
+/**
+ * atc_calc_bytes_left - calculates the number of bytes left according to the
+ * value read from CTRLA.
+ *
+ * @current_len: the number of bytes left before reading CTRLA
+ * @ctrla: the value of CTRLA
+ * @desc: the descriptor containing the transfer width
+ */
+static inline int atc_calc_bytes_left(int current_len, u32 ctrla,
+                                        struct at_desc *desc)
+{
+        return current_len - ((ctrla & ATC_BTSIZE_MAX) << desc->tx_width);
+}
+
+/**
+ * atc_calc_bytes_left_from_reg - calculates the number of bytes left according
+ * to the current value of CTRLA.
+ *
+ * @current_len: the number of bytes left before reading CTRLA
+ * @atchan: the channel to read CTRLA for
+ * @desc: the descriptor containing the transfer width
+ */
+static inline int atc_calc_bytes_left_from_reg(int current_len,
+                        struct at_dma_chan *atchan, struct at_desc *desc)
+{
+        u32 ctrla = channel_readl(atchan, CTRLA);
+
+        return atc_calc_bytes_left(current_len, ctrla, desc);
+}
+
+/**
+ * atc_get_bytes_left - get the number of bytes residue for a cookie
+ * @chan: DMA channel
+ * @cookie: transaction identifier to check status of
  */
-static int atc_get_bytes_left(struct dma_chan *chan)
+static int atc_get_bytes_left(struct dma_chan *chan, dma_cookie_t cookie)
 {
         struct at_dma_chan      *atchan = to_at_dma_chan(chan);
-        struct at_dma           *atdma = to_at_dma(chan->device);
-        int     chan_id = atchan->chan_common.chan_id;
         struct at_desc *desc_first = atc_first_active(atchan);
-        struct at_desc *desc_cur;
-        int ret = 0, count = 0;
+        struct at_desc *desc;
+        int ret;
+        u32 ctrla, dscr;
 
         /*
-         * Initialize necessary values in the first time.
-         * remain_desc record remain desc length.
+         * If the cookie doesn't match to the currently running transfer then
+         * we can return the total length of the associated DMA transfer,
+         * because it is still queued.
          */
-        if (atchan->remain_desc == 0)
-                /* First descriptor embedds the transaction length */
-                atchan->remain_desc = desc_first->len;
+        desc = atc_get_desc_by_cookie(atchan, cookie);
+        if (desc == NULL)
+                return -EINVAL;
+        else if (desc != desc_first)
+                return desc->total_len;
 
-        /*
-         * This happens when current descriptor transfer complete.
-         * The residual buffer size should reduce current descriptor length.
-         */
-        if (unlikely(test_bit(ATC_IS_BTC, &atchan->status))) {
-                clear_bit(ATC_IS_BTC, &atchan->status);
-                desc_cur = atc_get_current_descriptors(atchan,
-                                                channel_readl(atchan, DSCR));
-                if (!desc_cur) {
-                        ret = -EINVAL;
-                        goto out;
-                }
+        /* cookie matches to the currently running transfer */
+        ret = desc_first->total_len;
 
-                count = (desc_cur->lli.ctrla & ATC_BTSIZE_MAX)
-                        << desc_first->tx_width;
-                if (atchan->remain_desc < count) {
-                        ret = -EINVAL;
-                        goto out;
+        if (desc_first->lli.dscr) {
+                /* hardware linked list transfer */
+
+                /*
+                 * Calculate the residue by removing the length of the child
+                 * descriptors already transferred from the total length.
+                 * To get the current child descriptor we can use the value of
+                 * the channel's DSCR register and compare it against the value
+                 * of the hardware linked list structure of each child
+                 * descriptor.
+                 */
+
+                ctrla = channel_readl(atchan, CTRLA);
+                rmb(); /* ensure CTRLA is read before DSCR */
+                dscr = channel_readl(atchan, DSCR);
+
+                /* for the first descriptor we can be more accurate */
+                if (desc_first->lli.dscr == dscr)
+                        return atc_calc_bytes_left(ret, ctrla, desc_first);
+
+                ret -= desc_first->len;
+                list_for_each_entry(desc, &desc_first->tx_list, desc_node) {
+                        if (desc->lli.dscr == dscr)
+                                break;
+
+                        ret -= desc->len;
                 }
 
-                atchan->remain_desc -= count;
-                ret = atchan->remain_desc;
-        } else {
                 /*
-                 * Get residual bytes when current
-                 * descriptor transfer in progress.
+                 * For the last descriptor in the chain we can calculate
+                 * the remaining bytes using the channel's register.
+                 * Note that the transfer width of the first and last
+                 * descriptor may differ.
                  */
-                count = (channel_readl(atchan, CTRLA) & ATC_BTSIZE_MAX)
-                                << (desc_first->tx_width);
-                ret = atchan->remain_desc - count;
+                if (!desc->lli.dscr)
+                        ret = atc_calc_bytes_left_from_reg(ret, atchan, desc);
+        } else {
+                /* single transfer */
+                ret = atc_calc_bytes_left_from_reg(ret, atchan, desc_first);
         }
-        /*
-         * Check fifo empty.
-         */
-        if (!(dma_readl(atdma, CHSR) & AT_DMA_EMPT(chan_id)))
-                atc_issue_pending(chan);
 
-out:
         return ret;
 }
 
@@ -539,8 +572,6 @@ static irqreturn_t at_dma_interrupt(int irq, void *dev_id)
                                         /* Give information to tasklet */
                                         set_bit(ATC_IS_ERROR, &atchan->status);
                                 }
-                                if (pending & AT_DMA_BTC(i))
-                                        set_bit(ATC_IS_BTC, &atchan->status);
                                 tasklet_schedule(&atchan->tasklet);
                                 ret = IRQ_HANDLED;
                         }
@@ -653,14 +684,18 @@ atc_prep_dma_memcpy(struct dma_chan *chan, dma_addr_t dest, dma_addr_t src,
                 desc->lli.ctrlb = ctrlb;
 
                 desc->txd.cookie = 0;
+                desc->len = xfer_count << src_width;
 
                 atc_desc_chain(&first, &prev, desc);
         }
 
         /* First descriptor of the chain embedds additional information */
         first->txd.cookie = -EBUSY;
-        first->len = len;
+        first->total_len = len;
+
+        /* set transfer width for the calculation of the residue */
         first->tx_width = src_width;
+        prev->tx_width = src_width;
 
         /* set end-of-link to the last link descriptor of list*/
         set_desc_eol(desc);
@@ -752,6 +787,7 @@ atc_prep_slave_sg(struct dma_chan *chan, struct scatterlist *sgl,
                                         | ATC_SRC_WIDTH(mem_width)
                                         | len >> mem_width;
                         desc->lli.ctrlb = ctrlb;
+                        desc->len = len;
 
                         atc_desc_chain(&first, &prev, desc);
                         total_len += len;
@@ -792,6 +828,7 @@ atc_prep_slave_sg(struct dma_chan *chan, struct scatterlist *sgl,
                                         | ATC_DST_WIDTH(mem_width)
                                         | len >> reg_width;
                         desc->lli.ctrlb = ctrlb;
+                        desc->len = len;
 
                         atc_desc_chain(&first, &prev, desc);
                         total_len += len;
@@ -806,8 +843,11 @@ atc_prep_slave_sg(struct dma_chan *chan, struct scatterlist *sgl,
 
         /* First descriptor of the chain embedds additional information */
         first->txd.cookie = -EBUSY;
-        first->len = total_len;
+        first->total_len = total_len;
+
+        /* set transfer width for the calculation of the residue */
         first->tx_width = reg_width;
+        prev->tx_width = reg_width;
 
         /* first link descriptor of list is responsible of flags */
         first->txd.flags = flags; /* client is in control of this ack */
@@ -872,6 +912,7 @@ atc_dma_cyclic_fill_desc(struct dma_chan *chan, struct at_desc *desc,
                                 | ATC_FC_MEM2PER
                                 | ATC_SIF(atchan->mem_if)
                                 | ATC_DIF(atchan->per_if);
+                desc->len = period_len;
                 break;
 
         case DMA_DEV_TO_MEM:
@@ -883,6 +924,7 @@ atc_dma_cyclic_fill_desc(struct dma_chan *chan, struct at_desc *desc,
                                 | ATC_FC_PER2MEM
                                 | ATC_SIF(atchan->per_if)
                                 | ATC_DIF(atchan->mem_if);
+                desc->len = period_len;
                 break;
 
         default:
@@ -964,7 +1006,7 @@ atc_prep_dma_cyclic(struct dma_chan *chan, dma_addr_t buf_addr, size_t buf_len,
 
         /* First descriptor of the chain embedds additional information */
         first->txd.cookie = -EBUSY;
-        first->len = buf_len;
+        first->total_len = buf_len;
         first->tx_width = reg_width;
 
         return &first->txd;
@@ -1118,7 +1160,7 @@ atc_tx_status(struct dma_chan *chan,
         spin_lock_irqsave(&atchan->lock, flags);
 
         /*  Get number of bytes left in the active transactions */
-        bytes = atc_get_bytes_left(chan);
+        bytes = atc_get_bytes_left(chan, cookie);
 
         spin_unlock_irqrestore(&atchan->lock, flags);
 
@@ -1214,7 +1256,6 @@ static int atc_alloc_chan_resources(struct dma_chan *chan)
 
         spin_lock_irqsave(&atchan->lock, flags);
         atchan->descs_allocated = i;
-        atchan->remain_desc = 0;
         list_splice(&tmp_list, &atchan->free_list);
         dma_cookie_init(chan);
         spin_unlock_irqrestore(&atchan->lock, flags);
@@ -1257,7 +1298,6 @@ static void atc_free_chan_resources(struct dma_chan *chan)
         list_splice_init(&atchan->free_list, &list);
         atchan->descs_allocated = 0;
         atchan->status = 0;
-        atchan->remain_desc = 0;
 
         dev_vdbg(chan2dev(chan), "free_chan_resources: done\n");
 }
diff --git a/drivers/dma/at_hdmac_regs.h b/drivers/dma/at_hdmac_regs.h
index d6bba6c636c2..2727ca560572 100644
--- a/drivers/dma/at_hdmac_regs.h
+++ b/drivers/dma/at_hdmac_regs.h
@@ -181,8 +181,9 @@ struct at_lli {
  * @at_lli: hardware lli structure
  * @txd: support for the async_tx api
  * @desc_node: node on the channed descriptors list
- * @len: total transaction bytecount
+ * @len: descriptor byte count
  * @tx_width: transfer width
+ * @total_len: total transaction byte count
  */
 struct at_desc {
         /* FIRST values the hardware uses */
@@ -194,6 +195,7 @@ struct at_desc {
         struct list_head                desc_node;
         size_t                          len;
         u32                             tx_width;
+        size_t                          total_len;
 };
 
 static inline struct at_desc *
@@ -213,7 +215,6 @@ txd_to_at_desc(struct dma_async_tx_descriptor *txd)
 enum atc_status {
         ATC_IS_ERROR = 0,
         ATC_IS_PAUSED = 1,
-        ATC_IS_BTC = 2,
         ATC_IS_CYCLIC = 24,
 };
 
@@ -231,7 +232,6 @@ enum atc_status {
  * @save_cfg: configuration register that is saved on suspend/resume cycle
  * @save_dscr: for cyclic operations, preserve next descriptor address in
  *             the cyclic list on suspend/resume cycle
- * @remain_desc: to save remain desc length
  * @dma_sconfig: configuration for slave transfers, passed via
  * .device_config
  * @lock: serializes enqueue/dequeue operations to descriptors lists
@@ -251,7 +251,6 @@ struct at_dma_chan {
         struct tasklet_struct   tasklet;
         u32                     save_cfg;
         u32                     save_dscr;
-        u32                     remain_desc;
         struct dma_slave_config dma_sconfig;
 
         spinlock_t              lock;