phy: bcm-ns-usb2: new driver for USB 2.0 PHY on Northstar

Northstar is a family of SoCs used in home routers. They have USB 2.0
and 3.0 controllers with PHYs that need to be properly initialized.
This driver provides PHY init support in a generic way and can be bound
with an EHCI controller driver.
There are (just a few) registers being defined in bcma header. It's
because DMU/CRU registers will be also needed in other drivers. We will
need them e.g. in PCIe controller/PHY driver and at some point probably
in clock driver for BCM53573 chipset. By using include/linux/bcma/ we
avoid code duplication.

Signed-off-by: Rafał Miłecki <zajec5@gmail.com>
Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>

Documentation/devicetree/bindings/phy/bcm-ns-usb2-phy.txt

@@ -0,0 +1,21 @@
+Driver for Broadcom Northstar USB 2.0 PHY
+
+Required properties:
+- compatible: brcm,ns-usb2-phy
+- reg: iomem address range of DMU (Device Management Unit)
+- reg-names: "dmu", the only needed & supported reg right now
+- clocks: USB PHY reference clock
+- clock-names: "phy-ref-clk", the only needed & supported clock right now
+
+To initialize USB 2.0 PHY driver needs to setup PLL correctly. To do this it
+requires passing phandle to the USB PHY reference clock.
+
+Example:
+	usb2-phy {
+		compatible = "brcm,ns-usb2-phy";
+		reg = <0x1800c000 0x1000>;
+		reg-names = "dmu";
+		#phy-cells = <0>;
+		clocks = <&genpll BCM_NSP_GENPLL_USB_PHY_REF_CLK>;
+		clock-names = "phy-ref-clk";
+	};

drivers/phy/Kconfig

@@ -15,6 +15,15 @@ config GENERIC_PHY
 	  phy users can obtain reference to the PHY. All the users of this
 	  framework should select this config.
 
+config PHY_BCM_NS_USB2
+	tristate "Broadcom Northstar USB 2.0 PHY Driver"
+	depends on ARCH_BCM_IPROC || COMPILE_TEST
+	depends on HAS_IOMEM && OF
+	select GENERIC_PHY
+	help
+	  Enable this to support Broadcom USB 2.0 PHY connected to the USB
+	  controller on Northstar family.
+
 config PHY_BERLIN_USB
 	tristate "Marvell Berlin USB PHY Driver"
 	depends on ARCH_BERLIN && RESET_CONTROLLER && HAS_IOMEM && OF

drivers/phy/Makefile

@@ -3,6 +3,7 @@
 #
 
 obj-$(CONFIG_GENERIC_PHY)		+= phy-core.o
+obj-$(CONFIG_PHY_BCM_NS_USB2)		+= phy-bcm-ns-usb2.o
 obj-$(CONFIG_PHY_BERLIN_USB)		+= phy-berlin-usb.o
 obj-$(CONFIG_PHY_BERLIN_SATA)		+= phy-berlin-sata.o
 obj-$(CONFIG_PHY_DM816X_USB)		+= phy-dm816x-usb.o

drivers/phy/phy-bcm-ns-usb2.c

@@ -0,0 +1,137 @@
+/*
+ * Broadcom Northstar USB 2.0 PHY Driver
+ *
+ * Copyright (C) 2016 Rafał Miłecki <zajec5@gmail.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 as
+ * published by the Free Software Foundation.
+ *
+ */
+
+#include <linux/bcma/bcma.h>
+#include <linux/clk.h>
+#include <linux/delay.h>
+#include <linux/err.h>
+#include <linux/module.h>
+#include <linux/of_address.h>
+#include <linux/of_platform.h>
+#include <linux/phy/phy.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+
+struct bcm_ns_usb2 {
+	struct device *dev;
+	struct clk *ref_clk;
+	struct phy *phy;
+	void __iomem *dmu;
+};
+
+static int bcm_ns_usb2_phy_init(struct phy *phy)
+{
+	struct bcm_ns_usb2 *usb2 = phy_get_drvdata(phy);
+	struct device *dev = usb2->dev;
+	void __iomem *dmu = usb2->dmu;
+	u32 ref_clk_rate, usb2ctl, usb_pll_ndiv, usb_pll_pdiv;
+	int err = 0;
+
+	err = clk_prepare_enable(usb2->ref_clk);
+	if (err < 0) {
+		dev_err(dev, "Failed to prepare ref clock: %d\n", err);
+		goto err_out;
+	}
+
+	ref_clk_rate = clk_get_rate(usb2->ref_clk);
+	if (!ref_clk_rate) {
+		dev_err(dev, "Failed to get ref clock rate\n");
+		err = -EINVAL;
+		goto err_clk_off;
+	}
+
+	usb2ctl = readl(dmu + BCMA_DMU_CRU_USB2_CONTROL);
+
+	if (usb2ctl & BCMA_DMU_CRU_USB2_CONTROL_USB_PLL_PDIV_MASK) {
+		usb_pll_pdiv = usb2ctl;
+		usb_pll_pdiv &= BCMA_DMU_CRU_USB2_CONTROL_USB_PLL_PDIV_MASK;
+		usb_pll_pdiv >>= BCMA_DMU_CRU_USB2_CONTROL_USB_PLL_PDIV_SHIFT;
+	} else {
+		usb_pll_pdiv = 1 << 3;
+	}
+
+	/* Calculate ndiv based on a solid 1920 MHz that is for USB2 PHY */
+	usb_pll_ndiv = (1920000000 * usb_pll_pdiv) / ref_clk_rate;
+
+	/* Unlock DMU PLL settings with some magic value */
+	writel(0x0000ea68, dmu + BCMA_DMU_CRU_CLKSET_KEY);
+
+	/* Write USB 2.0 PLL control setting */
+	usb2ctl &= ~BCMA_DMU_CRU_USB2_CONTROL_USB_PLL_NDIV_MASK;
+	usb2ctl |= usb_pll_ndiv << BCMA_DMU_CRU_USB2_CONTROL_USB_PLL_NDIV_SHIFT;
+	writel(usb2ctl, dmu + BCMA_DMU_CRU_USB2_CONTROL);
+
+	/* Lock DMU PLL settings */
+	writel(0x00000000, dmu + BCMA_DMU_CRU_CLKSET_KEY);
+
+err_clk_off:
+	clk_disable_unprepare(usb2->ref_clk);
+err_out:
+	return err;
+}
+
+static const struct phy_ops ops = {
+	.init		= bcm_ns_usb2_phy_init,
+	.owner		= THIS_MODULE,
+};
+
+static int bcm_ns_usb2_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct bcm_ns_usb2 *usb2;
+	struct resource *res;
+	struct phy_provider *phy_provider;
+
+	usb2 = devm_kzalloc(&pdev->dev, sizeof(*usb2), GFP_KERNEL);
+	if (!usb2)
+		return -ENOMEM;
+	usb2->dev = dev;
+
+	res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "dmu");
+	usb2->dmu = devm_ioremap_resource(dev, res);
+	if (IS_ERR(usb2->dmu)) {
+		dev_err(dev, "Failed to map DMU regs\n");
+		return PTR_ERR(usb2->dmu);
+	}
+
+	usb2->ref_clk = devm_clk_get(dev, "phy-ref-clk");
+	if (IS_ERR(usb2->ref_clk)) {
+		dev_err(dev, "Clock not defined\n");
+		return PTR_ERR(usb2->ref_clk);
+	}
+
+	usb2->phy = devm_phy_create(dev, NULL, &ops);
+	if (IS_ERR(dev))
+		return PTR_ERR(dev);
+
+	phy_set_drvdata(usb2->phy, usb2);
+	platform_set_drvdata(pdev, usb2);
+
+	phy_provider = devm_of_phy_provider_register(dev, of_phy_simple_xlate);
+	return PTR_ERR_OR_ZERO(phy_provider);
+}
+
+static const struct of_device_id bcm_ns_usb2_id_table[] = {
+	{ .compatible = "brcm,ns-usb2-phy", },
+	{},
+};
+MODULE_DEVICE_TABLE(of, bcm_ns_usb2_id_table);
+
+static struct platform_driver bcm_ns_usb2_driver = {
+	.probe		= bcm_ns_usb2_probe,
+	.driver = {
+		.name = "bcm_ns_usb2",
+		.of_match_table = bcm_ns_usb2_id_table,
+	},
+};
+module_platform_driver(bcm_ns_usb2_driver);
+
+MODULE_LICENSE("GPL v2");

include/linux/bcma/bcma.h

@@ -4,6 +4,7 @@
 #include <linux/pci.h>
 #include <linux/mod_devicetable.h>
 
+#include <linux/bcma/bcma_driver_arm_c9.h>
 #include <linux/bcma/bcma_driver_chipcommon.h>
 #include <linux/bcma/bcma_driver_pci.h>
 #include <linux/bcma/bcma_driver_pcie2.h>

include/linux/bcma/bcma_driver_arm_c9.h

@@ -0,0 +1,15 @@
+#ifndef LINUX_BCMA_DRIVER_ARM_C9_H_
+#define LINUX_BCMA_DRIVER_ARM_C9_H_
+
+/* DMU (Device Management Unit) */
+#define BCMA_DMU_CRU_USB2_CONTROL			0x0164
+#define  BCMA_DMU_CRU_USB2_CONTROL_USB_PLL_NDIV_MASK	0x00000FFC
+#define  BCMA_DMU_CRU_USB2_CONTROL_USB_PLL_NDIV_SHIFT	2
+#define  BCMA_DMU_CRU_USB2_CONTROL_USB_PLL_PDIV_MASK	0x00007000
+#define  BCMA_DMU_CRU_USB2_CONTROL_USB_PLL_PDIV_SHIFT	12
+#define BCMA_DMU_CRU_CLKSET_KEY				0x0180
+#define BCMA_DMU_CRU_STRAPS_CTRL			0x02A0
+#define  BCMA_DMU_CRU_STRAPS_CTRL_USB3			0x00000010
+#define  BCMA_DMU_CRU_STRAPS_CTRL_4BYTE			0x00008000
+
+#endif /* LINUX_BCMA_DRIVER_ARM_C9_H_ */