dmaengine: shdma: Make second memory window optional
This patch makes the shdma.c driver allow slave operation
on DMA hardware mapped with a single I/O-memory window.
The dmae_set_dmars() function is adjusted to use the
first memory window in case of a missing DMARS window.
At probe() time the code is updated to enable DMA_SLAVE
only if slave information is passed with the platform data.
Signed-off-by: Magnus Damm <damm@opensource.se>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>
diff --git a/drivers/dma/shdma.c b/drivers/dma/shdma.c
index dcc1b21..3391b15 100644
--- a/drivers/dma/shdma.c
+++ b/drivers/dma/shdma.c
@@ -213,12 +213,17 @@
struct sh_dmae_device, common);
struct sh_dmae_pdata *pdata = shdev->pdata;
const struct sh_dmae_channel *chan_pdata = &pdata->channel[sh_chan->id];
- u16 __iomem *addr = shdev->dmars + chan_pdata->dmars / sizeof(u16);
+ u16 __iomem *addr = shdev->dmars;
int shift = chan_pdata->dmars_bit;
if (dmae_is_busy(sh_chan))
return -EBUSY;
+ /* in the case of a missing DMARS resource use first memory window */
+ if (!addr)
+ addr = (u16 __iomem *)shdev->chan_reg;
+ addr += chan_pdata->dmars / sizeof(u16);
+
__raw_writew((__raw_readw(addr) & (0xff00 >> shift)) | (val << shift),
addr);
@@ -1087,7 +1092,7 @@
return -ENODEV;
chan = platform_get_resource(pdev, IORESOURCE_MEM, 0);
- /* DMARS area is optional, if absent, this controller cannot do slave DMA */
+ /* DMARS area is optional */
dmars = platform_get_resource(pdev, IORESOURCE_MEM, 1);
/*
* IRQ resources:
@@ -1154,7 +1159,7 @@
INIT_LIST_HEAD(&shdev->common.channels);
dma_cap_set(DMA_MEMCPY, shdev->common.cap_mask);
- if (dmars)
+ if (pdata->slave && pdata->slave_num)
dma_cap_set(DMA_SLAVE, shdev->common.cap_mask);
shdev->common.device_alloc_chan_resources