[PATCH 3/5] usb: host: Add EHCI driver for Broadcom STB SoCs

[Al Cooper]

This driver enables USB EHCI on Broadcom ARM and MIPS STB SoCs.
The drivers depend on a matching "brcm,brcmstb-usb-phy"
Broadcom STB USB Phy driver.

The standard platform driver can't be used because of differences
in PHY and Clock handling. The standard PHY handling in hcd.c will
do a phy_exit/phy_init on suspend/resume and this will end up
shutting down the PHYs to the point that the host controller
registers are no longer accessible and will cause suspend to crash.
The clocks specified in device tree for these drivers are not
available in mainline so instead of returning EPROBE_DEFER when
the specified clock is not found and eventually failing probe,
the clock pointer is set to NULL which disables all clock handling.

Signed-off-by: Al Cooper <alcooperx@xxxxxxxxx>
---
 drivers/usb/host/ehci-brcm.c | 304 +++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 304 insertions(+)
 create mode 100644 drivers/usb/host/ehci-brcm.c

diff --git a/drivers/usb/host/ehci-brcm.c b/drivers/usb/host/ehci-brcm.c
new file mode 100644
index 000000000000..6bee4e0e2cbb
--- /dev/null
+++ b/drivers/usb/host/ehci-brcm.c
@@ -0,0 +1,304 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2018, Broadcom */
+
+#include <linux/acpi.h>
+#include <linux/clk.h>
+#include <linux/dma-mapping.h>
+#include <linux/err.h>
+#include <linux/kernel.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/usb.h>
+#include <linux/usb/hcd.h>
+
+#include "ehci.h"
+
+#define BRCM_DRIVER_DESC "EHCI Broadcom STB driver"
+
+#define hcd_to_ehci_priv(h) ((struct brcm_priv *)hcd_to_ehci(h)->priv)
+
+struct brcm_priv {
+	struct clk *clk;
+	struct phy *phy;
+};
+
+static const char brcm_hcd_name[] = "ehci-brcm";
+
+static int (*org_hub_control)(struct usb_hcd *hcd,
+			u16 typeReq, u16 wValue, u16 wIndex,
+			char *buf, u16 wLength);
+
+/* ehci_brcm_wait_for_sof
+ * Wait for start of next microframe, then wait extra delay microseconds
+ */
+static inline void ehci_brcm_wait_for_sof(struct ehci_hcd *ehci, u32 delay)
+{
+	int frame_idx = ehci_readl(ehci, &ehci->regs->frame_index);
+
+	while (frame_idx == ehci_readl(ehci, &ehci->regs->frame_index))
+		;
+	udelay(delay);
+}
+
+/*
+ * ehci_brcm_hub_control
+ * Intercept echi-hcd request to complete RESUME and align it to the start
+ * of the next microframe.
+ * If RESUME is complete too late in the microframe, host controller
+ * detects babble on suspended port and resets the port afterwards.
+ * This s/w workaround allows to avoid this problem.
+ * See SWLINUX-1909 for more details
+ */
+static int ehci_brcm_hub_control(
+	struct usb_hcd	*hcd,
+	u16		typeReq,
+	u16		wValue,
+	u16		wIndex,
+	char		*buf,
+	u16		wLength)
+{
+	struct ehci_hcd	*ehci = hcd_to_ehci(hcd);
+	int		ports = HCS_N_PORTS(ehci->hcs_params);
+	u32 __iomem	*status_reg = &ehci->regs->port_status[
+				(wIndex & 0xff) - 1];
+	unsigned long flags;
+	int retval, irq_disabled = 0;
+
+	/*
+	 * RESUME is cleared when GetPortStatus() is called 20ms after start
+	 * of RESUME
+	 */
+	if ((typeReq == GetPortStatus) &&
+	    (wIndex && wIndex <= ports) &&
+	    ehci->reset_done[wIndex-1] &&
+	    time_after_eq(jiffies, ehci->reset_done[wIndex-1]) &&
+	    (ehci_readl(ehci, status_reg) & PORT_RESUME)) {
+
+		/*
+		 * to make sure we are not interrupted until RESUME bit
+		 * is cleared, disable interrupts on current CPU
+		 */
+		ehci_dbg(ehci, "SOF alignment workaround\n");
+		irq_disabled = 1;
+		local_irq_save(flags);
+		ehci_brcm_wait_for_sof(ehci, 5);
+	}
+	retval = (*org_hub_control)(hcd, typeReq, wValue, wIndex, buf, wLength);
+	if (irq_disabled)
+		local_irq_restore(flags);
+	return retval;
+}
+
+static int ehci_brcm_reset(struct usb_hcd *hcd)
+{
+	struct ehci_hcd *ehci = hcd_to_ehci(hcd);
+
+	ehci->big_endian_mmio = 1;
+
+	ehci->caps = (struct ehci_caps *) hcd->regs;
+	ehci->regs = (struct ehci_regs *) (hcd->regs +
+		HC_LENGTH(ehci, ehci_readl(ehci, &ehci->caps->hc_capbase)));
+
+	/* This fixes the lockup during reboot due to prior interrupts */
+	ehci_writel(ehci, CMD_RESET, &ehci->regs->command);
+	mdelay(10);
+
+	/*
+	 * SWLINUX-1705: Avoid OUT packet underflows during high memory
+	 *   bus usage
+	 * port_status[0x0f] = Broadcom-proprietary USB_EHCI_INSNREG00 @ 0x90
+	 */
+	ehci_writel(ehci, 0x00800040, &ehci->regs->port_status[0x10]);
+	ehci_writel(ehci, 0x00000001, &ehci->regs->port_status[0x12]);
+
+	return ehci_setup(hcd);
+}
+
+static struct hc_driver __read_mostly ehci_brcm_hc_driver;
+
+static const struct ehci_driver_overrides brcm_overrides __initconst = {
+
+	.reset =	ehci_brcm_reset,
+	.extra_priv_size = sizeof(struct brcm_priv),
+};
+
+static int ehci_brcm_probe(struct platform_device *pdev)
+{
+	struct usb_hcd *hcd;
+	struct resource *res_mem;
+	struct brcm_priv *priv;
+	int irq;
+	int err;
+
+	if (usb_disabled())
+		return -ENODEV;
+
+	err = dma_coerce_mask_and_coherent(&pdev->dev, DMA_BIT_MASK(32));
+	if (err)
+		return err;
+
+	irq = platform_get_irq(pdev, 0);
+	if (irq < 0) {
+		dev_err(&pdev->dev, "no irq provided");
+		return irq;
+	}
+
+	/* Hook the hub control routine to work around a bug */
+	if (org_hub_control == NULL)
+		org_hub_control = ehci_brcm_hc_driver.hub_control;
+	ehci_brcm_hc_driver.hub_control = ehci_brcm_hub_control;
+
+	/* initialize hcd */
+	hcd = usb_create_hcd(&ehci_brcm_hc_driver,
+			&pdev->dev, dev_name(&pdev->dev));
+	if (!hcd)
+		return -ENOMEM;
+
+	platform_set_drvdata(pdev, hcd);
+	priv = hcd_to_ehci_priv(hcd);
+
+	priv->clk = devm_clk_get(&pdev->dev, NULL);
+	if (IS_ERR(priv->clk)) {
+		dev_err(&pdev->dev, "Clock not found in Device Tree\n");
+		priv->clk = NULL;
+	}
+	err = clk_prepare_enable(priv->clk);
+	if (err)
+		goto err_hcd;
+
+	priv->phy = devm_of_phy_get_by_index(&pdev->dev, pdev->dev.of_node, 0);
+	if (IS_ERR(priv->phy)) {
+		dev_err(&pdev->dev, "USB Phy not found.\n");
+		err = PTR_ERR(priv->phy);
+		goto err_clk;
+	}
+	phy_init(priv->phy);
+
+	res_mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	hcd->regs = devm_ioremap_resource(&pdev->dev, res_mem);
+	if (IS_ERR(hcd->regs)) {
+		err = PTR_ERR(hcd->regs);
+		goto err_phy;
+	}
+	hcd->rsrc_start = res_mem->start;
+	hcd->rsrc_len = resource_size(res_mem);
+	hcd->skip_phy_initialization = 1;
+	err = usb_add_hcd(hcd, irq, IRQF_SHARED);
+	if (err)
+		goto err_phy;
+
+	device_wakeup_enable(hcd->self.controller);
+	device_enable_async_suspend(hcd->self.controller);
+	platform_set_drvdata(pdev, hcd);
+
+	return err;
+
+err_phy:
+	phy_exit(priv->phy);
+err_clk:
+	clk_disable_unprepare(priv->clk);
+err_hcd:
+	usb_put_hcd(hcd);
+
+	return err;
+}
+
+static int ehci_brcm_remove(struct platform_device *dev)
+{
+	struct usb_hcd *hcd = platform_get_drvdata(dev);
+	struct brcm_priv *priv = hcd_to_ehci_priv(hcd);
+
+	usb_remove_hcd(hcd);
+	phy_exit(priv->phy);
+	clk_disable_unprepare(priv->clk);
+	usb_put_hcd(hcd);
+	return 0;
+}
+
+#ifdef CONFIG_PM_SLEEP
+
+static int ehci_brcm_suspend(struct device *dev)
+{
+	int ret;
+	struct usb_hcd *hcd = dev_get_drvdata(dev);
+	struct brcm_priv *priv = hcd_to_ehci_priv(hcd);
+	bool do_wakeup = device_may_wakeup(dev);
+
+	ret = ehci_suspend(hcd, do_wakeup);
+	clk_disable_unprepare(priv->clk);
+	return ret;
+}
+
+static int ehci_brcm_resume(struct device *dev)
+{
+	struct usb_hcd *hcd = dev_get_drvdata(dev);
+	struct ehci_hcd *ehci = hcd_to_ehci(hcd);
+	struct brcm_priv *priv = hcd_to_ehci_priv(hcd);
+	int err;
+
+	err = clk_prepare_enable(priv->clk);
+	if (err)
+		return err;
+	/*
+	 * SWLINUX-1705: Avoid OUT packet underflows during high memory
+	 *   bus usage
+	 * port_status[0x0f] = Broadcom-proprietary USB_EHCI_INSNREG00
+	 * @ 0x90
+	 */
+	ehci_writel(ehci, 0x00800040, &ehci->regs->port_status[0x10]);
+	ehci_writel(ehci, 0x00000001, &ehci->regs->port_status[0x12]);
+
+	ehci_resume(hcd, false);
+	return 0;
+}
+#endif /* CONFIG_PM_SLEEP */
+
+static SIMPLE_DEV_PM_OPS(ehci_brcm_pm_ops, ehci_brcm_suspend,
+		ehci_brcm_resume);
+
+#ifdef CONFIG_OF
+static const struct of_device_id brcm_ehci_of_match[] = {
+	{ .compatible = "brcm,ehci-brcm-v2", },
+	{}
+};
+
+MODULE_DEVICE_TABLE(of, brcm_ehci_of_match);
+#endif /* CONFIG_OF */
+
+static struct platform_driver ehci_brcm_driver = {
+	.probe		= ehci_brcm_probe,
+	.remove		= ehci_brcm_remove,
+	.shutdown	= usb_hcd_platform_shutdown,
+	.driver		= {
+		.owner	= THIS_MODULE,
+		.name	= "ehci-brcm",
+		.pm	= &ehci_brcm_pm_ops,
+		.of_match_table = of_match_ptr(brcm_ehci_of_match),
+	}
+};
+
+static int __init ehci_brcm_init(void)
+{
+	if (usb_disabled())
+		return -ENODEV;
+
+	pr_info("%s: " BRCM_DRIVER_DESC "\n", brcm_hcd_name);
+
+	ehci_init_driver(&ehci_brcm_hc_driver, &brcm_overrides);
+	return platform_driver_register(&ehci_brcm_driver);
+}
+module_init(ehci_brcm_init);
+
+static void __exit ehci_brcm_exit(void)
+{
+	platform_driver_unregister(&ehci_brcm_driver);
+}
+module_exit(ehci_brcm_exit);
+
+MODULE_ALIAS("platform:ehci-brcm");
+MODULE_DESCRIPTION(BRCM_DRIVER_DESC);
+MODULE_AUTHOR("Al Cooper");
+MODULE_LICENSE("GPL");
-- 
1.9.0.138.g2de3478