dmaengine: ste_dma40: Fetch disabled channels from DT

Some platforms have channels which are not available for normal use.
This information is currently passed though platform data in internal
BSP kernels. Once those platforms land, they'll need to configure them
appropriately, so we may as well add the infrastructure.

Cc: Dan Williams <djbw@fb.com>
Cc: Per Forlin <per.forlin@stericsson.com>
Cc: Rabin Vincent <rabin@rab.in>
Acked-by: Vinod Koul <vinod.koul@intel.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

2 files changed, 18 insertions, 1 deletions

diff --git a/Documentation/devicetree/bindings/dma/ste-dma40.txt b/Documentation/devicetree/bindings/dma/ste-dma40.txt
index aa272d866f6e..bea5b73a7390 100644
--- a/Documentation/devicetree/bindings/dma/ste-dma40.txt
+++ b/Documentation/devicetree/bindings/dma/ste-dma40.txt
@@ -11,6 +11,7 @@ Required properties:
 Optional properties:
 - dma-channels: Number of channels supported by hardware - if not present
                 the driver will attempt to obtain the information from H/W
+- disabled-channels: Channels which can not be used
 
 Example:
 
@@ -23,6 +24,7 @@ Example:
 
                 #dma-cells = <2>;
                 memcpy-channels  = <56 57 58 59 60>;
+                disabled-channels  = <12>;
                 dma-channels = <8>;
         };
 
diff --git a/drivers/dma/ste_dma40.c b/drivers/dma/ste_dma40.c
index 4e528dd30ad5..ffac8225ff54 100644
--- a/drivers/dma/ste_dma40.c
+++ b/drivers/dma/ste_dma40.c
@@ -3482,7 +3482,7 @@ static int __init d40_of_probe(struct platform_device *pdev,
                                struct device_node *np)
 {
         struct stedma40_platform_data *pdata;
-        int num_phy = 0, num_memcpy = 0;
+        int num_phy = 0, num_memcpy = 0, num_disabled = 0;
         const const __be32 *list;
 
         pdata = devm_kzalloc(&pdev->dev,
@@ -3511,6 +3511,21 @@ static int __init d40_of_probe(struct platform_device *pdev,
                                    dma40_memcpy_channels,
                                    num_memcpy);
 
+        list = of_get_property(np, "disabled-channels", &num_disabled);
+        num_disabled /= sizeof(*list);
+
+        if (num_disabled > STEDMA40_MAX_PHYS || num_disabled < 0) {
+                d40_err(&pdev->dev,
+                        "Invalid number of disabled channels specified (%d)\n",
+                        num_disabled);
+                return -EINVAL;
+        }
+
+        of_property_read_u32_array(np, "disabled-channels",
+                                   pdata->disabled_channels,
+                                   num_disabled);
+        pdata->disabled_channels[num_disabled] = -1;
+
         pdev->dev.platform_data = pdata;
 
         return 0;