[ARM] 4177/1: S3C24XX: Add DMA channel allocation order
Allow the CPU code, and any board specific initialisation
code to change the allocation order of the DMA channels,
or stop a peripheral allocating any DMA at-all.
This is due to the scarce mapping of DMA channels on
some earlier S3C24XX cpus, where the selection changes
depending on the channel in use.
Signed-off-by: Ben Dooks <ben-linux@fluff.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
diff --git a/arch/arm/plat-s3c24xx/dma.c b/arch/arm/plat-s3c24xx/dma.c
index c784e1f..44e3943 100644
--- a/arch/arm/plat-s3c24xx/dma.c
+++ b/arch/arm/plat-s3c24xx/dma.c
@@ -1354,18 +1354,22 @@
return (channel & DMA_CH_VALID);
}
+static struct s3c24xx_dma_order *dma_order;
+
+
/* s3c2410_dma_map_channel()
*
* turn the virtual channel number into a real, and un-used hardware
* channel.
*
- * currently this code uses first-free channel from the specified harware
- * map, not taking into account anything that the board setup code may
- * have to say about the likely peripheral set to be in use.
+ * first, try the dma ordering given to us by either the relevant
+ * dma code, or the board. Then just find the first usable free
+ * channel
*/
struct s3c2410_dma_chan *s3c2410_dma_map_channel(int channel)
{
+ struct s3c24xx_dma_order_ch *ord = NULL;
struct s3c24xx_dma_map *ch_map;
struct s3c2410_dma_chan *dmach;
int ch;
@@ -1375,6 +1379,27 @@
ch_map = dma_sel.map + channel;
+ /* first, try the board mapping */
+
+ if (dma_order) {
+ ord = &dma_order->channels[channel];
+
+ for (ch = 0; ch < S3C2410_DMA_CHANNELS; ch++) {
+ if (!is_channel_valid(ord->list[ch]))
+ continue;
+
+ if (s3c2410_chans[ord->list[ch]].in_use == 0) {
+ ch = ord->list[ch] & ~DMA_CH_VALID;
+ goto found;
+ }
+ }
+
+ if (ord->flags & DMA_CH_NEVER)
+ return NULL;
+ }
+
+ /* second, search the channel map for first free */
+
for (ch = 0; ch < S3C2410_DMA_CHANNELS; ch++) {
if (!is_channel_valid(ch_map->channels[ch]))
continue;
@@ -1390,6 +1415,7 @@
/* update our channel mapping */
+ found:
dmach = &s3c2410_chans[ch];
dma_chan_map[channel] = dmach;
@@ -1439,3 +1465,20 @@
return 0;
}
+
+int __init s3c24xx_dma_order_set(struct s3c24xx_dma_order *ord)
+{
+ struct s3c24xx_dma_order *nord = dma_order;
+
+ if (nord == NULL)
+ nord = kmalloc(sizeof(struct s3c24xx_dma_order), GFP_KERNEL);
+
+ if (nord == NULL) {
+ printk(KERN_ERR "no memory to store dma channel order\n");
+ return -ENOMEM;
+ }
+
+ dma_order = nord;
+ memcpy(nord, ord, sizeof(struct s3c24xx_dma_order));
+ return 0;
+}