[PATCH v2 2/2] ASoC: fsl_sai: Allow setting the SAI MCLK direction

[Fabio Estevam <festevam@gmail.com>]

From: Fabio Estevam <fabio.estevam@nxp.com>

On mx6ul the General Purpose Register 1 (GPR1) contains the following
bits for configuring the direction of the SAI MCLKs:
SAI1_MCLK_DIR, SAI2_MCLK_DIR, SAI3_MCLK_DIR

Introduce  the "fsl,sai-mclk-direction-output" optional property to allow
configuring the SAI_MCLK outputs.

Tested on a imx6ul-evk board.

Signed-off-by: Fabio Estevam <fabio.estevam@nxp.com>
---
Changes since v1:
- Dropped unneeded gpr node.
- Change the property name to fsl,sai-mclk-direction-output. (Nicolin)
- Do a runtime check against fsl,imx6ul-sai. (Nicolin)
- Use macro instead of switch statement. (Nicolin)

 .../devicetree/bindings/sound/fsl-sai.txt          |  5 +++++
 include/linux/mfd/syscon/imx6q-iomuxc-gpr.h        |  6 ++++++
 sound/soc/fsl/fsl_sai.c                            | 22 ++++++++++++++++++++++
 3 files changed, 33 insertions(+)

diff --git a/Documentation/devicetree/bindings/sound/fsl-sai.txt b/Documentation/devicetree/bindings/sound/fsl-sai.txt
index 044e5d7..bec3ae0 100644
--- a/Documentation/devicetree/bindings/sound/fsl-sai.txt
+++ b/Documentation/devicetree/bindings/sound/fsl-sai.txt
@@ -48,6 +48,11 @@ Required properties:
 			  receive data by following their own bit clocks and
 			  frame sync clocks separately.
 
+Optional properties (for mx6ul):
+
+  - fsl,sai-mclk-direction-output: This is a boolean property. If present,
+			 indicates that SAI will output the SAI MCLK clock.
+
 Note:
 - If both fsl,sai-asynchronous and fsl,sai-synchronous-rx are absent, the
   default synchronous mode (sync Rx with Tx) will be used, which means both
diff --git a/include/linux/mfd/syscon/imx6q-iomuxc-gpr.h b/include/linux/mfd/syscon/imx6q-iomuxc-gpr.h
index 238c8db..6835382 100644
--- a/include/linux/mfd/syscon/imx6q-iomuxc-gpr.h
+++ b/include/linux/mfd/syscon/imx6q-iomuxc-gpr.h
@@ -447,5 +447,11 @@
 #define IMX6UL_GPR1_ENET2_CLK_OUTPUT		(0x1 << 18)
 #define IMX6UL_GPR1_ENET_CLK_DIR		(0x3 << 17)
 #define IMX6UL_GPR1_ENET_CLK_OUTPUT		(0x3 << 17)
+#define IMX6UL_GPR1_SAI1_MCLK_DIR		(0x1 << 19)
+#define IMX6UL_GPR1_SAI2_MCLK_DIR		(0x1 << 20)
+#define IMX6UL_GPR1_SAI3_MCLK_DIR		(0x1 << 21)
+#define IMX6UL_GPR1_SAI_MCLK_MASK		(0x7 << 19)
+#define MCLK_DIR(x) (x == 1 ? IMX6UL_GPR1_SAI1_MCLK_DIR : x == 2 ? \
+		     IMX6UL_GPR1_SAI2_MCLK_DIR : IMX6UL_GPR1_SAI3_MCLK_DIR)
 
 #endif /* __LINUX_IMX6Q_IOMUXC_GPR_H */
diff --git a/sound/soc/fsl/fsl_sai.c b/sound/soc/fsl/fsl_sai.c
index d8b673f..506a5f8 100644
--- a/sound/soc/fsl/fsl_sai.c
+++ b/sound/soc/fsl/fsl_sai.c
@@ -21,6 +21,8 @@
 #include <sound/core.h>
 #include <sound/dmaengine_pcm.h>
 #include <sound/pcm_params.h>
+#include <linux/mfd/syscon.h>
+#include <linux/mfd/syscon/imx6q-iomuxc-gpr.h>
 
 #include "fsl_sai.h"
 #include "imx-pcm.h"
@@ -786,10 +788,12 @@ static int fsl_sai_probe(struct platform_device *pdev)
 {
 	struct device_node *np = pdev->dev.of_node;
 	struct fsl_sai *sai;
+	struct regmap *gpr;
 	struct resource *res;
 	void __iomem *base;
 	char tmp[8];
 	int irq, ret, i;
+	u32 index;
 
 	sai = devm_kzalloc(&pdev->dev, sizeof(*sai), GFP_KERNEL);
 	if (!sai)
@@ -878,6 +882,24 @@ static int fsl_sai_probe(struct platform_device *pdev)
 		fsl_sai_dai.symmetric_samplebits = 0;
 	}
 
+	if (of_find_property(np, "fsl,sai-mclk-direction-output", NULL) &&
+	    of_device_is_compatible(pdev->dev.of_node, "fsl,imx6ul-sai")) {
+		gpr = syscon_regmap_lookup_by_compatible("fsl,imx6ul-iomuxc-gpr");
+		if (IS_ERR(gpr)) {
+			dev_err(&pdev->dev, "cannot find iomuxc registers\n");
+			return PTR_ERR(gpr);
+		}
+
+		ret = of_property_read_u32(np, "sai-index", &index);
+		if (ret) {
+			dev_err(&pdev->dev, "could not read sai-index\n");
+			return ret;
+		}
+
+		regmap_update_bits(gpr, IOMUXC_GPR1, MCLK_DIR(index),
+				   MCLK_DIR(index));
+	}
+
 	sai->dma_params_rx.addr = res->start + FSL_SAI_RDR;
 	sai->dma_params_tx.addr = res->start + FSL_SAI_TDR;
 	sai->dma_params_rx.maxburst = FSL_SAI_MAXBURST_RX;
-- 
1.9.1