dmaengine: xgene-dma: Add ACPI support for X-Gene DMA engine driver

This patch adds ACPI support for the APM X-Gene DMA engine driver.
Signed-off-by: Rameshwar Prasad Sahu <rsahu@apm.com>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>

drivers/dma/xgene-dma.c

@@ -21,6 +21,7 @@
  * NOTE: PM support is currently not available.
  */
 
+#include <linux/acpi.h>
 #include <linux/clk.h>
 #include <linux/delay.h>
 #include <linux/dma-mapping.h>
@@ -1940,16 +1941,18 @@ static int xgene_dma_probe(struct platform_device *pdev)
 		return ret;
 
 	pdma->clk = devm_clk_get(&pdev->dev, NULL);
-	if (IS_ERR(pdma->clk)) {
+	if (IS_ERR(pdma->clk) && !ACPI_COMPANION(&pdev->dev)) {
 		dev_err(&pdev->dev, "Failed to get clk\n");
 		return PTR_ERR(pdma->clk);
 	}
 
 	/* Enable clk before accessing registers */
-	ret = clk_prepare_enable(pdma->clk);
-	if (ret) {
-		dev_err(&pdev->dev, "Failed to enable clk %d\n", ret);
-		return ret;
+	if (!IS_ERR(pdma->clk)) {
+		ret = clk_prepare_enable(pdma->clk);
+		if (ret) {
+			dev_err(&pdev->dev, "Failed to enable clk %d\n", ret);
+			return ret;
+		}
 	}
 
 	/* Remove DMA RAM out of shutdown */
@@ -1994,7 +1997,8 @@ static int xgene_dma_probe(struct platform_device *pdev)
 
 err_dma_mask:
 err_clk_enable:
-	clk_disable_unprepare(pdma->clk);
+	if (!IS_ERR(pdma->clk))
+		clk_disable_unprepare(pdma->clk);
 
 	return ret;
 }
@@ -2018,11 +2022,20 @@ static int xgene_dma_remove(struct platform_device *pdev)
 		xgene_dma_delete_chan_rings(chan);
 	}
 
-	clk_disable_unprepare(pdma->clk);
+	if (!IS_ERR(pdma->clk))
+		clk_disable_unprepare(pdma->clk);
 
 	return 0;
 }
 
+#ifdef CONFIG_ACPI
+static const struct acpi_device_id xgene_dma_acpi_match_ptr[] = {
+	{"APMC0D43", 0},
+	{},
+};
+MODULE_DEVICE_TABLE(acpi, xgene_dma_acpi_match_ptr);
+#endif
+
 static const struct of_device_id xgene_dma_of_match_ptr[] = {
 	{.compatible = "apm,xgene-storm-dma",},
 	{},
@@ -2035,6 +2048,7 @@ static struct platform_driver xgene_dma_driver = {
 	.driver = {
 		.name = "X-Gene-DMA",
 		.of_match_table = xgene_dma_of_match_ptr,
+		.acpi_match_table = ACPI_PTR(xgene_dma_acpi_match_ptr),
 	},
 };