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ARM: OMAP: Get available DMA channels from cmdline 

This patch set up a cmdline option for omap dma for masking the
available channels. It is needed since the OMAP DMA is a system wide
resource and can be used by another software apart from the kernel.

To reserve the omap SDMA channels for kernel dma usage, use cmdline
bootarg "omap_dma_reserve_ch=". The valid range is 1 to 32.

Signed-off-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
Acked-by: Nishant Kamat <nskamat@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>
This commit is contained in:
Santosh Shilimkar 2009-03-23 18:07:48 -07:00 committed by Tony Lindgren
parent 7954763bb9
commit 2263f0222e
1 changed files with 19 additions and 1 deletions
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20
arch/arm/plat-omap/dma.c
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@ -123,6 +123,7 @@ static struct dma_link_info *dma_linked_lch;
static int dma_lch_count;
static int dma_chan_count;
static int omap_dma_reserve_channels;
static spinlock_t dma_chan_lock;
static struct omap_dma_lch *dma_chan;
@ -2321,6 +2322,10 @@ static int __init omap_init_dma(void)
return -ENODEV;
}
if (cpu_class_is_omap2() && omap_dma_reserve_channels
&& (omap_dma_reserve_channels <= dma_lch_count))
dma_lch_count = omap_dma_reserve_channels;
dma_chan = kzalloc(sizeof(struct omap_dma_lch) * dma_lch_count,
GFP_KERNEL);
if (!dma_chan)
@ -2371,7 +2376,7 @@ static int __init omap_init_dma(void)
u8 revision = dma_read(REVISION) & 0xff;
printk(KERN_INFO "OMAP DMA hardware revision %d.%d\n",
revision >> 4, revision & 0xf);
dma_chan_count = OMAP_DMA4_LOGICAL_DMA_CH_COUNT;
dma_chan_count = dma_lch_count;
} else {
dma_chan_count = 0;
return 0;
@ -2437,4 +2442,17 @@ static int __init omap_init_dma(void)
arch_initcall(omap_init_dma);
/*
* Reserve the omap SDMA channels using cmdline bootarg
* "omap_dma_reserve_ch=". The valid range is 1 to 32
*/
static int __init omap_dma_cmdline_reserve_ch(char *str)
{
if (get_option(&str, &omap_dma_reserve_channels) != 1)
omap_dma_reserve_channels = 0;
return 1;
}
__setup("omap_dma_reserve_ch=", omap_dma_cmdline_reserve_ch);