dma: sh: use an integer slave ID to improve API compatibility

Initially struct shdma_slave has been introduced with the only member - an
unsigned slave ID - to describe common properties of DMA slaves in an
extensible way. However, experience shows, that a slave ID is indeed the
only parameter, needed to identify DMA slaves. This is also, what is used
by the core dmaengine API in struct dma_slave_config. We switch to using
the slave_id directly, instead of passing a pointer to struct shdma_slave
to improve compatibility with the core. We also make the slave_id signed
for easier error checking.

Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
Signed-off-by: Vinod Koul <vinod.koul@linux.intel.com>

1 files changed, 13 insertions, 12 deletions

diff --git a/drivers/dma/sh/shdma-base.c b/drivers/dma/sh/shdma-base.c
index f75ebfa735c0..73db282a1436 100644
--- a/drivers/dma/sh/shdma-base.c
+++ b/drivers/dma/sh/shdma-base.c
@@ -76,7 +76,6 @@ static dma_cookie_t shdma_tx_submit(struct dma_async_tx_descriptor *tx)
                 container_of(tx, struct shdma_desc, async_tx),
                 *last = desc;
         struct shdma_chan *schan = to_shdma_chan(tx->chan);
-        struct shdma_slave *slave = schan->slave;
         dma_async_tx_callback callback = tx->callback;
         dma_cookie_t cookie;
         bool power_up;
@@ -138,7 +137,7 @@ static dma_cookie_t shdma_tx_submit(struct dma_async_tx_descriptor *tx)
                          * Make it int then, on error remove chunks from the
                          * queue again
                          */
-                        ops->setup_xfer(schan, slave);
+                        ops->setup_xfer(schan, schan->slave_id);
 
                         if (schan->pm_state == SHDMA_PM_PENDING)
                                 shdma_chan_xfer_ld_queue(schan);
@@ -186,7 +185,7 @@ static int shdma_alloc_chan_resources(struct dma_chan *chan)
          * never runs concurrently with itself or free_chan_resources.
          */
         if (slave) {
-                if (slave->slave_id >= slave_num) {
+                if (slave->slave_id < 0 || slave->slave_id >= slave_num) {
                         ret = -EINVAL;
                         goto evalid;
                 }
@@ -196,9 +195,13 @@ static int shdma_alloc_chan_resources(struct dma_chan *chan)
                         goto etestused;
                 }
 
-                ret = ops->set_slave(schan, slave);
+                ret = ops->set_slave(schan, slave->slave_id);
                 if (ret < 0)
                         goto esetslave;
+
+                schan->slave_id = slave->slave_id;
+        } else {
+                schan->slave_id = -EINVAL;
         }
 
         schan->desc = kcalloc(NR_DESCS_PER_CHANNEL,
@@ -208,7 +211,6 @@ static int shdma_alloc_chan_resources(struct dma_chan *chan)
                 goto edescalloc;
         }
         schan->desc_num = NR_DESCS_PER_CHANNEL;
-        schan->slave = slave;
 
         for (i = 0; i < NR_DESCS_PER_CHANNEL; i++) {
                 desc = ops->embedded_desc(schan->desc, i);
@@ -366,10 +368,9 @@ static void shdma_free_chan_resources(struct dma_chan *chan)
         if (!list_empty(&schan->ld_queue))
                 shdma_chan_ld_cleanup(schan, true);
 
-        if (schan->slave) {
+        if (schan->slave_id >= 0) {
                 /* The caller is holding dma_list_mutex */
-                struct shdma_slave *slave = schan->slave;
-                clear_bit(slave->slave_id, shdma_slave_used);
+                clear_bit(schan->slave_id, shdma_slave_used);
                 chan->private = NULL;
         }
 
@@ -559,7 +560,7 @@ static struct dma_async_tx_descriptor *shdma_prep_slave_sg(
         struct shdma_chan *schan = to_shdma_chan(chan);
         struct shdma_dev *sdev = to_shdma_dev(schan->dma_chan.device);
         const struct shdma_ops *ops = sdev->ops;
-        struct shdma_slave *slave = schan->slave;
+        int slave_id = schan->slave_id;
         dma_addr_t slave_addr;
 
         if (!chan)
@@ -568,9 +569,9 @@ static struct dma_async_tx_descriptor *shdma_prep_slave_sg(
         BUG_ON(!schan->desc_num);
 
         /* Someone calling slave DMA on a generic channel? */
-        if (!slave || !sg_len) {
-                dev_warn(schan->dev, "%s: bad parameter: %p, %d, %d\n",
-                         __func__, slave, sg_len, slave ? slave->slave_id : -1);
+        if (slave_id < 0 || !sg_len) {
+                dev_warn(schan->dev, "%s: bad parameter: len=%d, id=%d\n",
+                         __func__, sg_len, slave_id);
                 return NULL;
         }