[PATCH v3] dmaengine: mv_xor_v2: Fix clock resource by adding a register clock

[Gregory CLEMENT]

On the CP110 components which are present on the Armada 7K/8K SoC we need
to explicitly enable the clock for the registers. However it is not
needed for the AP8xx component, that's why this clock is optional.

With this patch both clock have now a name, but in order to be backward
compatible, the name of the first clock is not used. It allows to still
use this clock with a device tree using the old binding.

Signed-off-by: Gregory CLEMENT <gregory.clement at bootlin.com>
---
Changelog:

v1 -> v2

 - Fix typos in the commit log
 - Add more explanation in te commit log
 - Only skip the reg clock usage if the clock is not presetn in the
   device tree (-ENOENT)
 - Add dt list in CC

v2 -> v3

 - Fix the ENOENT test

 .../devicetree/bindings/dma/mv-xor-v2.txt          |  6 +++++-
 drivers/dma/mv_xor_v2.c                            | 25 +++++++++++++++++-----
 2 files changed, 25 insertions(+), 6 deletions(-)

diff --git a/Documentation/devicetree/bindings/dma/mv-xor-v2.txt b/Documentation/devicetree/bindings/dma/mv-xor-v2.txt
index 217a90eaabe7..9c38bbe7e6d7 100644
--- a/Documentation/devicetree/bindings/dma/mv-xor-v2.txt
+++ b/Documentation/devicetree/bindings/dma/mv-xor-v2.txt
@@ -11,7 +11,11 @@ Required properties:
   interrupts.
 
 Optional properties:
-- clocks: Optional reference to the clock used by the XOR engine.
+- clocks: Optional reference to the clocks used by the XOR engine.
+- clock-names: mandatory if there is a second clock, in this case the
+   name must be "core" for the first clock and "reg" for the second
+   one
+
 
 Example:
 
diff --git a/drivers/dma/mv_xor_v2.c b/drivers/dma/mv_xor_v2.c
index f652a0e0f5a2..3548caa9e933 100644
--- a/drivers/dma/mv_xor_v2.c
+++ b/drivers/dma/mv_xor_v2.c
@@ -163,6 +163,7 @@ struct mv_xor_v2_device {
 	void __iomem *dma_base;
 	void __iomem *glob_base;
 	struct clk *clk;
+	struct clk *reg_clk;
 	struct tasklet_struct irq_tasklet;
 	struct list_head free_sw_desc;
 	struct dma_device dmadev;
@@ -749,13 +750,26 @@ static int mv_xor_v2_probe(struct platform_device *pdev)
 	if (ret)
 		return ret;
 
+	xor_dev->reg_clk = devm_clk_get(&pdev->dev, "reg");
+	if (PTR_ERR(xor_dev->reg_clk) != -ENOENT) {
+		if (!IS_ERR(xor_dev->reg_clk)) {
+			ret = clk_prepare_enable(xor_dev->reg_clk);
+			if (ret)
+				return ret;
+		} else {
+			return PTR_ERR(xor_dev->reg_clk);
+		}
+	}
+
 	xor_dev->clk = devm_clk_get(&pdev->dev, NULL);
-	if (IS_ERR(xor_dev->clk) && PTR_ERR(xor_dev->clk) == -EPROBE_DEFER)
-		return -EPROBE_DEFER;
+	if (IS_ERR(xor_dev->clk) && PTR_ERR(xor_dev->clk) == -EPROBE_DEFER) {
+		ret = EPROBE_DEFER;
+		goto disable_reg_clk;
+	}
 	if (!IS_ERR(xor_dev->clk)) {
 		ret = clk_prepare_enable(xor_dev->clk);
 		if (ret)
-			return ret;
+			goto disable_reg_clk;
 	}
 
 	ret = platform_msi_domain_alloc_irqs(&pdev->dev, 1,
@@ -866,8 +880,9 @@ static int mv_xor_v2_probe(struct platform_device *pdev)
 free_msi_irqs:
 	platform_msi_domain_free_irqs(&pdev->dev);
 disable_clk:
-	if (!IS_ERR(xor_dev->clk))
-		clk_disable_unprepare(xor_dev->clk);
+	clk_disable_unprepare(xor_dev->clk);
+disable_reg_clk:
+	clk_disable_unprepare(xor_dev->reg_clk);
 	return ret;
 }
 
-- 
2.16.1