usb: dwc3: add generic OF glue layer

For simple platforms which merely enable some clocks
and populate its children, we can use this generic
glue layer to avoid boilerplate code duplication.

For now this supports Qcom and Xilinx, but if we
find a way to add generic handling of regulators and
optional PHYs, we can absorb exynos as well.

Tested-by: Subbaraya Sundeep Bhatta <subbaraya.sundeep.bhatta@xilinx.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>

drivers/usb/dwc3/Kconfig

@@ -87,6 +87,15 @@ config USB_DWC3_KEYSTONE
 	  Support of USB2/3 functionality in TI Keystone2 platforms.
 	  Say 'Y' or 'M' here if you have one such device
 
+config USB_DWC3_OF_SIMPLE
+       tristate "Generic OF Simple Glue Layer"
+       depends on OF && COMMON_CLK
+       default USB_DWC3
+       help
+         Support USB2/3 functionality in simple SoC integrations.
+	 Currently supports Xilinx and Qualcomm DWC USB3 IP.
+	 Say 'Y' or 'M' if you have one such device.
+
 config USB_DWC3_ST
 	tristate "STMicroelectronics Platforms"
 	depends on ARCH_STI && OF

drivers/usb/dwc3/Makefile

@@ -37,5 +37,6 @@ obj-$(CONFIG_USB_DWC3_OMAP)		+= dwc3-omap.o
 obj-$(CONFIG_USB_DWC3_EXYNOS)		+= dwc3-exynos.o
 obj-$(CONFIG_USB_DWC3_PCI)		+= dwc3-pci.o
 obj-$(CONFIG_USB_DWC3_KEYSTONE)		+= dwc3-keystone.o
+obj-$(CONFIG_USB_DWC3_OF_SIMPLE)	+= dwc3-of-simple.o
 obj-$(CONFIG_USB_DWC3_QCOM)		+= dwc3-qcom.o
 obj-$(CONFIG_USB_DWC3_ST)		+= dwc3-st.o

drivers/usb/dwc3/dwc3-of-simple.c

@@ -0,0 +1,178 @@
+/**
+ * dwc3-of-simple.c - OF glue layer for simple integrations
+ *
+ * Copyright (c) 2015 Texas Instruments Incorporated - http://www.ti.com
+ *
+ * Author: Felipe Balbi <balbi@ti.com>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2  of
+ * the License as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * This is a combination of the old dwc3-qcom.c by Ivan T. Ivanov
+ * <iivanov@mm-sol.com> and the original patch adding support for Xilinx' SoC
+ * by Subbaraya Sundeep Bhatta <subbaraya.sundeep.bhatta@xilinx.com>
+ */
+
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include <linux/platform_device.h>
+#include <linux/dma-mapping.h>
+#include <linux/clk.h>
+#include <linux/clk-provider.h>
+#include <linux/of.h>
+#include <linux/of_platform.h>
+#include <linux/pm_runtime.h>
+
+struct dwc3_of_simple {
+	struct device		*dev;
+	struct clk		**clks;
+	int			num_clocks;
+};
+
+static int dwc3_of_simple_probe(struct platform_device *pdev)
+{
+	struct dwc3_of_simple	*simple;
+	struct device		*dev = &pdev->dev;
+	struct device_node	*np = dev->of_node;
+
+	int			ret;
+	int			i;
+
+	simple = devm_kzalloc(dev, sizeof(*simple), GFP_KERNEL);
+	if (!simple)
+		return -ENOMEM;
+
+	ret = of_clk_get_parent_count(np);
+	if (ret < 0)
+		return ret;
+
+	simple->num_clocks = ret;
+
+	simple->clks = devm_kcalloc(dev, simple->num_clocks,
+			sizeof(struct clk *), GFP_KERNEL);
+	if (!simple->clks)
+		return -ENOMEM;
+
+	simple->dev = dev;
+
+	for (i = 0; i < simple->num_clocks; i++) {
+		struct clk	*clk;
+
+		clk = of_clk_get(np, i);
+		if (IS_ERR(clk)) {
+			while (--i >= 0)
+				clk_put(simple->clks[i]);
+			return PTR_ERR(clk);
+		}
+
+		ret = clk_prepare_enable(clk);
+		if (ret < 0) {
+			while (--i >= 0) {
+				clk_disable_unprepare(simple->clks[i]);
+				clk_put(simple->clks[i]);
+			}
+			clk_put(clk);
+
+			return ret;
+		}
+
+		simple->clks[i] = clk;
+	}
+
+	ret = of_platform_populate(np, NULL, NULL, dev);
+	if (ret) {
+		for (i = 0; i < simple->num_clocks; i++) {
+			clk_disable_unprepare(simple->clks[i]);
+			clk_put(simple->clks[i]);
+		}
+
+		return ret;
+	}
+
+	pm_runtime_set_active(dev);
+	pm_runtime_enable(dev);
+	pm_runtime_get_sync(dev);
+
+	return 0;
+}
+
+static int dwc3_of_simple_remove(struct platform_device *pdev)
+{
+	struct dwc3_of_simple	*simple = platform_get_drvdata(pdev);
+	struct device		*dev = &pdev->dev;
+	int			i;
+
+	for (i = 0; i < simple->num_clocks; i++) {
+		clk_unprepare(simple->clks[i]);
+		clk_put(simple->clks[i]);
+	}
+
+	of_platform_depopulate(dev);
+
+	pm_runtime_put_sync(dev);
+	pm_runtime_disable(dev);
+
+	return 0;
+}
+
+static int dwc3_of_simple_runtime_suspend(struct device *dev)
+{
+	struct dwc3_of_simple	*simple = dev_get_drvdata(dev);
+	int			i;
+
+	for (i = 0; i < simple->num_clocks; i++)
+		clk_disable(simple->clks[i]);
+
+	return 0;
+}
+
+static int dwc3_of_simple_runtime_resume(struct device *dev)
+{
+	struct dwc3_of_simple	*simple = dev_get_drvdata(dev);
+	int			ret;
+	int			i;
+
+	for (i = 0; i < simple->num_clocks; i++) {
+		ret = clk_enable(simple->clks[i]);
+		if (ret < 0) {
+			while (--i >= 0)
+				clk_disable(simple->clks[i]);
+			return ret;
+		}
+	}
+
+	return 0;
+}
+
+static const struct dev_pm_ops dwc3_of_simple_dev_pm_ops = {
+	SET_RUNTIME_PM_OPS(dwc3_of_simple_runtime_suspend,
+			dwc3_of_simple_runtime_resume, NULL)
+};
+
+static const struct of_device_id of_dwc3_simple_match[] = {
+	{ .compatible = "qcom,dwc3" },
+	{ .compatible = "xlnx,zynqmp-dwc3" },
+	{ /* Sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, of_dwc3_simple_match);
+
+static struct platform_driver dwc3_of_simple_driver = {
+	.probe		= dwc3_of_simple_probe,
+	.remove		= dwc3_of_simple_remove,
+	.driver		= {
+		.name	= "dwc3-of-simple",
+		.of_match_table = of_dwc3_simple_match,
+	},
+};
+
+module_platform_driver(dwc3_of_simple_driver);
+MODULE_LICENSE("GPL v2");
+MODULE_DESCRIPTION("DesignWare USB3 OF Simple Glue Layer");
+MODULE_AUTHOR("Felipe Balbi <balbi@ti.com>");