dma: mmp_pdma: add filter function

PXA peripherals need to obtain specific DMA request ids which will
eventually be stored in the DRCMR register.

Currently, clients are expected to store that number inside the slave
config block as slave_id, which is unfortunately incompatible with the
way DMA resources are handled in DT environments.

This patch adds a filter function which stores the filter parameter
passed in by of-dma.c into the channel's drcmr register.

For backward compatability, cfg->slave_id is still used if set to
a non-zero value.

Signed-off-by: Daniel Mack <zonque@gmail.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>

1 files changed, 20 insertions, 1 deletions

diff --git a/drivers/dma/mmp_pdma.c b/drivers/dma/mmp_pdma.c
index eb75d4b4bafe1..dd024d4759e7e 100644
--- a/drivers/dma/mmp_pdma.c
+++ b/drivers/dma/mmp_pdma.c
@@ -19,6 +19,7 @@
 #include <linux/dmapool.h>
 #include <linux/of_device.h>
 #include <linux/of.h>
+#include <linux/dma/mmp-pdma.h>
 
 #include "dmaengine.h"
 
@@ -635,8 +636,13 @@ static int mmp_pdma_control(struct dma_chan *dchan, enum dma_ctrl_cmd cmd,
 			chan->dcmd |= DCMD_BURST32;
 
 		chan->dir = cfg->direction;
-		chan->drcmr = cfg->slave_id;
 		chan->dev_addr = addr;
+		/* FIXME: drivers should be ported over to use the filter
+		 * function. Once that's done, the following two lines can
+		 * be removed.
+		 */
+		if (cfg->slave_id)
+			chan->drcmr = cfg->slave_id;
 		break;
 	default:
 		return -ENOSYS;
@@ -877,6 +883,19 @@ static struct platform_driver mmp_pdma_driver = {
 	.remove		= mmp_pdma_remove,
 };
 
+bool mmp_pdma_filter_fn(struct dma_chan *chan, void *param)
+{
+	struct mmp_pdma_chan *c = to_mmp_pdma_chan(chan);
+
+	if (chan->device->dev->driver != &mmp_pdma_driver.driver)
+		return false;
+
+	c->drcmr = *(unsigned int *) param;
+
+	return true;
+}
+EXPORT_SYMBOL_GPL(mmp_pdma_filter_fn);
+
 module_platform_driver(mmp_pdma_driver);
 
 MODULE_DESCRIPTION("MARVELL MMP Periphera DMA Driver");