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authorBen Dooks <ben-linux@fluff.org>2007-02-13 13:02:52 +0100
committerRussell King <rmk+kernel@arm.linux.org.uk>2007-02-14 15:04:22 +0000
commit0c6022d453ecebdace0ce15434c7108e158149ca (patch)
tree153ce6dd661059601fa8591d36e0b81c6663566a /arch
parentd2a76020e3a52c6370a7d603082b4cdb3db0703e (diff)
[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>
Diffstat (limited to 'arch')
-rw-r--r--arch/arm/plat-s3c24xx/dma.c49
1 files changed, 46 insertions, 3 deletions
diff --git a/arch/arm/plat-s3c24xx/dma.c b/arch/arm/plat-s3c24xx/dma.c
index c784e1f816b..44e39438b9d 100644
--- a/arch/arm/plat-s3c24xx/dma.c
+++ b/arch/arm/plat-s3c24xx/dma.c
@@ -1354,18 +1354,22 @@ static inline int is_channel_valid(unsigned int channel)
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 @@ struct s3c2410_dma_chan *s3c2410_dma_map_channel(int channel)
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 @@ struct s3c2410_dma_chan *s3c2410_dma_map_channel(int channel)
/* update our channel mapping */
+ found:
dmach = &s3c2410_chans[ch];
dma_chan_map[channel] = dmach;
@@ -1439,3 +1465,20 @@ int __init s3c24xx_dma_init_map(struct s3c24xx_dma_selection *sel)
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;
+}