Commit 2263f022 authored by Santosh Shilimkar's avatar Santosh Shilimkar Committed by Tony Lindgren
Browse files

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: default avatarSantosh Shilimkar <santosh.shilimkar@ti.com>
Acked-by: default avatarNishant Kamat <nskamat@ti.com>
Signed-off-by: default avatarTony Lindgren <tony@atomide.com>
parent 7954763b

arch/arm/plat-omap/dma.c

+19 −1
Original line number Diff line number Diff line
@@ -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);

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