dmaengine: rcar-dmac: Add dma-channel-mask property support

This patch adds dma-channel-mask property support not to reserve
some DMA channels for some reasons. (for example: a heterogeneous
CPU uses it.)

Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Reviewed-by: Simon Horman <horms+renesas@verge.net.au>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/1568010892-17606-5-git-send-email-yoshihiro.shimoda.uh@renesas.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>

diff --git a/drivers/dma/sh/rcar-dmac.c b/drivers/dma/sh/rcar-dmac.c
index 542786de69a99eb25dd5c8bcfad94fe3bf703e4e..f06016d38a05f284ffabd53d54e267300979bb06 100644 (file)
--- a/drivers/dma/sh/rcar-dmac.c
+++ b/drivers/dma/sh/rcar-dmac.c
@@ -203,7 +203,7 @@ struct rcar_dmac {
 
        unsigned int n_channels;
        struct rcar_dmac_chan *channels;
-       unsigned int channels_mask;
+       u32 channels_mask;
 
        DECLARE_BITMAP(modules, 256);
 };
@@ -1810,7 +1810,15 @@ static int rcar_dmac_parse_of(struct device *dev, struct rcar_dmac *dmac)
                return -EINVAL;
        }
 
+       /*
+        * If the driver is unable to read dma-channel-mask property,
+        * the driver assumes that it can use all channels.
+        */
        dmac->channels_mask = GENMASK(dmac->n_channels - 1, 0);
+       of_property_read_u32(np, "dma-channel-mask", &dmac->channels_mask);
+
+       /* If the property has out-of-channel mask, this driver clears it */
+       dmac->channels_mask &= GENMASK(dmac->n_channels - 1, 0);
 
        return 0;
 }