usb: host: ehci-st: Add EHCI support for ST STB devices

This patch adds the glue code required to ensure the on-chip EHCI
controller works on STi consumer electronics SoC's from STMicroelectronics.

It mainly manages the setting and enabling of the relevant clocks and manages
the reset / power signals to the IP block.
Signed-off-by: Peter Griffin <peter.griffin@linaro.org>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/host/ehci-st.c

+/*
+ * ST EHCI driver
+ *
+ * Copyright (C) 2014 STMicroelectronics – All Rights Reserved
+ *
+ * Author: Peter Griffin <peter.griffin@linaro.org>
+ *
+ * Derived from ehci-platform.c
+ *
+ * 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/clk.h>
+#include <linux/dma-mapping.h>
+#include <linux/err.h>
+#include <linux/kernel.h>
+#include <linux/hrtimer.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/phy/phy.h>
+#include <linux/platform_device.h>
+#include <linux/reset.h>
+#include <linux/usb.h>
+#include <linux/usb/hcd.h>
+#include <linux/usb/ehci_pdriver.h>
+
+#include "ehci.h"
+
+#define USB_MAX_CLKS 3
+
+struct st_ehci_platform_priv {
+	struct clk *clks[USB_MAX_CLKS];
+	struct clk *clk48;
+	struct reset_control *rst;
+	struct reset_control *pwr;
+	struct phy *phy;
+};
+
+#define DRIVER_DESC "EHCI STMicroelectronics driver"
+
+#define hcd_to_ehci_priv(h) \
+	((struct st_ehci_platform_priv *)hcd_to_ehci(h)->priv)
+
+static const char hcd_name[] = "ehci-st";
+
+#define EHCI_CAPS_SIZE 0x10
+#define AHB2STBUS_INSREG01 (EHCI_CAPS_SIZE + 0x84)
+
+static int st_ehci_platform_reset(struct usb_hcd *hcd)
+{
+	struct platform_device *pdev = to_platform_device(hcd->self.controller);
+	struct usb_ehci_pdata *pdata = dev_get_platdata(&pdev->dev);
+	struct ehci_hcd *ehci = hcd_to_ehci(hcd);
+	int retval;
+	u32 threshold;
+
+	/* Set EHCI packet buffer IN/OUT threshold to 128 bytes */
+	threshold = 128 | (128 << 16);
+	writel(threshold, hcd->regs + AHB2STBUS_INSREG01);
+
+	ehci->caps = hcd->regs + pdata->caps_offset;
+	retval = ehci_setup(hcd);
+	if (retval)
+		return retval;
+
+	return 0;
+}
+
+static int st_ehci_platform_power_on(struct platform_device *dev)
+{
+	struct usb_hcd *hcd = platform_get_drvdata(dev);
+	struct st_ehci_platform_priv *priv = hcd_to_ehci_priv(hcd);
+	int clk, ret;
+
+	ret = reset_control_deassert(priv->pwr);
+	if (ret)
+		return ret;
+
+	ret = reset_control_deassert(priv->rst);
+	if (ret)
+		goto err_assert_power;
+
+	/* some SoCs don't have a dedicated 48Mhz clock, but those that do
+	   need the rate to be explicitly set */
+	if (priv->clk48) {
+		ret = clk_set_rate(priv->clk48, 48000000);
+		if (ret)
+			goto err_assert_reset;
+	}
+
+	for (clk = 0; clk < USB_MAX_CLKS && priv->clks[clk]; clk++) {
+		ret = clk_prepare_enable(priv->clks[clk]);
+		if (ret)
+			goto err_disable_clks;
+	}
+
+	ret = phy_init(priv->phy);
+	if (ret)
+		goto err_disable_clks;
+
+	ret = phy_power_on(priv->phy);
+	if (ret)
+		goto err_exit_phy;
+
+	return 0;
+
+err_exit_phy:
+	phy_exit(priv->phy);
+err_disable_clks:
+	while (--clk >= 0)
+		clk_disable_unprepare(priv->clks[clk]);
+err_assert_reset:
+	reset_control_assert(priv->rst);
+err_assert_power:
+	reset_control_assert(priv->pwr);
+
+	return ret;
+}
+
+static void st_ehci_platform_power_off(struct platform_device *dev)
+{
+	struct usb_hcd *hcd = platform_get_drvdata(dev);
+	struct st_ehci_platform_priv *priv = hcd_to_ehci_priv(hcd);
+	int clk;
+
+	reset_control_assert(priv->pwr);
+
+	reset_control_assert(priv->rst);
+
+	phy_power_off(priv->phy);
+
+	phy_exit(priv->phy);
+
+	for (clk = USB_MAX_CLKS - 1; clk >= 0; clk--)
+		if (priv->clks[clk])
+			clk_disable_unprepare(priv->clks[clk]);
+
+}
+
+static struct hc_driver __read_mostly ehci_platform_hc_driver;
+
+static const struct ehci_driver_overrides platform_overrides __initconst = {
+	.reset =		st_ehci_platform_reset,
+	.extra_priv_size =	sizeof(struct st_ehci_platform_priv),
+};
+
+static struct usb_ehci_pdata ehci_platform_defaults = {
+	.power_on =		st_ehci_platform_power_on,
+	.power_suspend =	st_ehci_platform_power_off,
+	.power_off =		st_ehci_platform_power_off,
+};
+
+static int st_ehci_platform_probe(struct platform_device *dev)
+{
+	struct usb_hcd *hcd;
+	struct resource *res_mem;
+	struct usb_ehci_pdata *pdata = &ehci_platform_defaults;
+	struct st_ehci_platform_priv *priv;
+	struct ehci_hcd *ehci;
+	int err, irq, clk = 0;
+
+	if (usb_disabled())
+		return -ENODEV;
+
+	irq = platform_get_irq(dev, 0);
+	if (irq < 0) {
+		dev_err(&dev->dev, "no irq provided");
+		return irq;
+	}
+	res_mem = platform_get_resource(dev, IORESOURCE_MEM, 0);
+	if (!res_mem) {
+		dev_err(&dev->dev, "no memory resource provided");
+		return -ENXIO;
+	}
+
+	hcd = usb_create_hcd(&ehci_platform_hc_driver, &dev->dev,
+			     dev_name(&dev->dev));
+	if (!hcd)
+		return -ENOMEM;
+
+	platform_set_drvdata(dev, hcd);
+	dev->dev.platform_data = pdata;
+	priv = hcd_to_ehci_priv(hcd);
+	ehci = hcd_to_ehci(hcd);
+
+	priv->phy = devm_phy_get(&dev->dev, "usb");
+	if (IS_ERR(priv->phy)) {
+		err = PTR_ERR(priv->phy);
+		goto err_put_hcd;
+	}
+
+	for (clk = 0; clk < USB_MAX_CLKS; clk++) {
+		priv->clks[clk] = of_clk_get(dev->dev.of_node, clk);
+		if (IS_ERR(priv->clks[clk])) {
+			err = PTR_ERR(priv->clks[clk]);
+			if (err == -EPROBE_DEFER)
+				goto err_put_clks;
+			priv->clks[clk] = NULL;
+			break;
+		}
+	}
+
+	/* some SoCs don't have a dedicated 48Mhz clock, but those that
+	   do need the rate to be explicitly set */
+	priv->clk48 = devm_clk_get(&dev->dev, "clk48");
+	if (IS_ERR(priv->clk48)) {
+		dev_info(&dev->dev, "48MHz clk not found\n");
+		priv->clk48 = NULL;
+	}
+
+	priv->pwr = devm_reset_control_get_optional(&dev->dev, "power");
+	if (IS_ERR(priv->pwr)) {
+		err = PTR_ERR(priv->pwr);
+		if (err == -EPROBE_DEFER)
+			goto err_put_clks;
+		priv->pwr = NULL;
+	}
+
+	priv->rst = devm_reset_control_get_optional(&dev->dev, "softreset");
+	if (IS_ERR(priv->rst)) {
+		err = PTR_ERR(priv->rst);
+		if (err == -EPROBE_DEFER)
+			goto err_put_clks;
+		priv->rst = NULL;
+	}
+
+	if (pdata->power_on) {
+		err = pdata->power_on(dev);
+		if (err < 0)
+			goto err_put_clks;
+	}
+
+	hcd->rsrc_start = res_mem->start;
+	hcd->rsrc_len = resource_size(res_mem);
+
+	hcd->regs = devm_ioremap_resource(&dev->dev, res_mem);
+	if (IS_ERR(hcd->regs)) {
+		err = PTR_ERR(hcd->regs);
+		goto err_put_clks;
+	}
+
+	err = usb_add_hcd(hcd, irq, IRQF_SHARED);
+	if (err)
+		goto err_put_clks;
+
+	device_wakeup_enable(hcd->self.controller);
+	platform_set_drvdata(dev, hcd);
+
+	return err;
+
+err_put_clks:
+	while (--clk >= 0)
+		clk_put(priv->clks[clk]);
+err_put_hcd:
+	if (pdata == &ehci_platform_defaults)
+		dev->dev.platform_data = NULL;
+
+	usb_put_hcd(hcd);
+
+	return err;
+}
+
+static int st_ehci_platform_remove(struct platform_device *dev)
+{
+	struct usb_hcd *hcd = platform_get_drvdata(dev);
+	struct usb_ehci_pdata *pdata = dev_get_platdata(&dev->dev);
+	struct st_ehci_platform_priv *priv = hcd_to_ehci_priv(hcd);
+	int clk;
+
+	usb_remove_hcd(hcd);
+
+	if (pdata->power_off)
+		pdata->power_off(dev);
+
+	for (clk = 0; clk < USB_MAX_CLKS && priv->clks[clk]; clk++)
+		clk_put(priv->clks[clk]);
+
+	usb_put_hcd(hcd);
+
+	if (pdata == &ehci_platform_defaults)
+		dev->dev.platform_data = NULL;
+
+	return 0;
+}
+
+#ifdef CONFIG_PM_SLEEP
+
+static int st_ehci_suspend(struct device *dev)
+{
+	struct usb_hcd *hcd = dev_get_drvdata(dev);
+	struct usb_ehci_pdata *pdata = dev_get_platdata(dev);
+	struct platform_device *pdev =
+		container_of(dev, struct platform_device, dev);
+	bool do_wakeup = device_may_wakeup(dev);
+	int ret;
+
+	ret = ehci_suspend(hcd, do_wakeup);
+	if (ret)
+		return ret;
+
+	if (pdata->power_suspend)
+		pdata->power_suspend(pdev);
+
+	pinctrl_pm_select_sleep_state(dev);
+
+	return ret;
+}
+
+static int st_ehci_resume(struct device *dev)
+{
+	struct usb_hcd *hcd = dev_get_drvdata(dev);
+	struct usb_ehci_pdata *pdata = dev_get_platdata(dev);
+	struct platform_device *pdev =
+		container_of(dev, struct platform_device, dev);
+	int err;
+
+	pinctrl_pm_select_default_state(dev);
+
+	if (pdata->power_on) {
+		err = pdata->power_on(pdev);
+		if (err < 0)
+			return err;
+	}
+
+	ehci_resume(hcd, false);
+	return 0;
+}
+
+static SIMPLE_DEV_PM_OPS(st_ehci_pm_ops, st_ehci_suspend, st_ehci_resume);
+
+#endif /* CONFIG_PM_SLEEP */
+
+static const struct of_device_id st_ehci_ids[] = {
+	{ .compatible = "st,st-ehci-300x", },
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, st_ehci_ids);
+
+static struct platform_driver ehci_platform_driver = {
+	.probe		= st_ehci_platform_probe,
+	.remove		= st_ehci_platform_remove,
+	.shutdown	= usb_hcd_platform_shutdown,
+	.driver		= {
+		.name	= "st-ehci",
+#ifdef CONFIG_PM_SLEEP
+		.pm	= &st_ehci_pm_ops,
+#endif
+		.of_match_table = st_ehci_ids,
+	}
+};
+
+static int __init ehci_platform_init(void)
+{
+	if (usb_disabled())
+		return -ENODEV;
+
+	pr_info("%s: " DRIVER_DESC "\n", hcd_name);
+
+	ehci_init_driver(&ehci_platform_hc_driver, &platform_overrides);
+	return platform_driver_register(&ehci_platform_driver);
+}
+module_init(ehci_platform_init);
+
+static void __exit ehci_platform_cleanup(void)
+{
+	platform_driver_unregister(&ehci_platform_driver);
+}
+module_exit(ehci_platform_cleanup);
+
+MODULE_DESCRIPTION(DRIVER_DESC);
+MODULE_AUTHOR("Peter Griffin <peter.griffin@linaro.org>");
+MODULE_LICENSE("GPL");