Device tree overlay for fclk[0..3] created. Driver for fclk created to be able...

Device tree overlay for fclk[0..3] created. Driver for fclk created to be able to change the frequency.

.gitignore

+# Ignore unnecessary file in driver folders
+*.tmp_versions
+*.cmd
+*.mod.c
+*.o
+*.symvers
+*.order
+

driver/fclk/Makefile

+obj-m += fclk.o
+ 
+all:
+	make -C /lib/modules/$(shell uname -r)/build M=$(PWD) modules
+ 
+clean:
+	make -C /lib/modules/$(shell uname -r)/build M=$(PWD) clean

driver/fclk/fclk.c

+#include <linux/module.h>			// included for all kernel modules
+#include <linux/init.h>				// included for __init and __exit macros
+#include <linux/platform_device.h>
+#include <linux/of_platform.h>
+#include <linux/clk.h>
+
+MODULE_LICENSE("GPL v2");
+MODULE_AUTHOR("Johannes Feldmann");
+MODULE_DESCRIPTION("This module configures an fclk with settings from a device tree");
+
+///////////////////////////////////////////////////////////////////////////////////////////////////
+// Devicetree structures
+/*
+fclk_0: fclk@0 {
+	compatible = "jf,fclk-1.0.0";
+	reg = <0>;
+	
+	clocks = <&clkc 15>;
+	freq-in-hz = <200000000>;
+};
+*/
+
+///////////////////////////////////////////////////////////////////////////////////////////////////
+// Driver structures
+struct fclk_state {
+	struct device	*pDev;
+	struct clk		*pClk;
+	u32				nFreq;
+};
+
+///////////////////////////////////////////////////////////////////////////////////////////////////
+// Function definitions
+static int fclk_probe(struct platform_device *pdev)
+{
+	struct fclk_state *pState;
+	int ret;
+
+	// Allocate memory for driver structure
+	pState = devm_kzalloc(&pdev->dev, sizeof(*pState), GFP_KERNEL);
+	if(!pState)
+		return -ENOMEM;
+	
+	// Save device
+	pState->pDev = &pdev->dev;
+	
+	// Set driver data
+	platform_set_drvdata(pdev, pState);
+	
+	// Get clock
+	pState->pClk = devm_clk_get(&pdev->dev, NULL);
+	if(IS_ERR(pState->pClk))
+	{
+		dev_err(&pdev->dev, "fclk: failed to get clock");
+		return PTR_ERR(pState->pClk);
+	}
+	
+	// Get Clock frequency
+	of_property_read_u32(pdev->dev.of_node, "freq-in-hz", &pState->nFreq);
+	
+	ret = clk_set_rate(pState->pClk, pState->nFreq);
+	if(ret != 0)
+	{
+		dev_err(&pdev->dev, "fclk: Frequency set to %d failed", pState->nFreq);
+		return ret;
+	}
+	
+	dev_info(&pdev->dev, "fclk: Frequency set to %d", pState->nFreq);
+	
+	// Enable clock
+	//ret = clk_prepare_enable(pState->pClk);
+	if(ret != 0)
+	{
+		dev_err(&pdev->dev, "fclk: Failed to enalbe Clock");
+		return ret;
+	}
+	
+	dev_info(&pdev->dev, "fclk: Probe successful for (%s)\n", pdev->name);
+	
+	return 0;
+}
+
+static int fclk_remove(struct platform_device *pdev)
+{
+	struct fclk_state *pState = platform_get_drvdata(pdev);
+
+	//clk_disable_unprepare(pState->pClk);
+	
+	dev_info(&pdev->dev, "fclk: Removal successful\n");
+	return 0;
+}
+
+///////////////////////////////////////////////////////////////////////////////////////////////////
+// Driver definition
+static const struct of_device_id fclk_of_ids[] = {
+	{ .compatible = "jf,fclk-1.0.0",},
+	{}
+};
+
+static struct platform_driver fclk_driver = {
+	.driver = {
+		.name = "fclk",
+		.owner = THIS_MODULE,
+		.of_match_table = fclk_of_ids,
+	},
+	.probe = fclk_probe,
+	.remove = fclk_remove,
+};
+
+module_platform_driver(fclk_driver);

dt-overlay/fclk/fclk.dts

+/dts-v1/;
+/plugin/;
+
+/ {
+	compatible = "xlnx,zynq-7000";
+	
+	fragment@0 {
+		target-path = "/";
+		__overlay__ {
+		
+			fclk_0: fclk@0 {
+				compatible = "jf,fclk-1.0.0";
+				
+				clocks = <&clkc 15>;
+				freq-in-hz = <160000000>;
+			};
+			fclk_1: fclk@1 {
+				compatible = "jf,fclk-1.0.0";
+				
+				clocks = <&clkc 16>;
+				freq-in-hz = <100000000>;
+			};
+			fclk_2: fclk@2 {
+				compatible = "jf,fclk-1.0.0";
+				
+				clocks = <&clkc 17>;
+				freq-in-hz = <200000000>;
+			};
+			fclk_3: fclk@3 {
+				compatible = "jf,fclk-1.0.0";
+				
+				clocks = <&clkc 18>;
+				freq-in-hz = <000000000>;
+			};
+		};
+	};
+};
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