/*-
 * SPDX-License-Identifier: ISC
 *
 * Copyright (c) 2020 Dr Robert Harvey Crowston <crowston@protonmail.com>
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 *
 *
 */

/*
 * VIA VL805 controller on the Raspberry Pi 4.
 * The VL805 is a generic xhci controller. However, in the newer hardware
 * revisions of the Raspberry Pi 4, it is incapable of loading its own firmware.
 * Instead, the VideoCore GPU must load the firmware into the controller at the
 * appropriate time. This driver is a shim that pre-loads the firmware before
 * handing control to the xhci generic driver.
 */

#include <sys/cdefs.h>
#include <sys/stdint.h>
#include <sys/stddef.h>
#include <sys/param.h>
#include <sys/queue.h>
#include <sys/types.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/bus.h>
#include <sys/module.h>
#include <sys/lock.h>
#include <sys/mutex.h>
#include <sys/condvar.h>
#include <sys/sysctl.h>
#include <sys/sx.h>
#include <sys/unistd.h>
#include <sys/callout.h>
#include <sys/malloc.h>
#include <sys/priv.h>

#include <dev/usb/usb.h>
#include <dev/usb/usbdi.h>

#include <dev/usb/usb_core.h>
#include <dev/usb/usb_busdma.h>
#include <dev/usb/usb_process.h>
#include <dev/usb/usb_util.h>

#include <dev/usb/usb_controller.h>
#include <dev/usb/usb_bus.h>
#include <dev/usb/usb_pci.h>
#include <dev/usb/controller/xhci.h>

#include <dev/ofw/openfirm.h>
#include <dev/ofw/ofw_bus.h>
#include <dev/ofw/ofw_bus_subr.h>

#include <arm/broadcom/bcm2835/bcm2835_mbox_prop.h>

#define VL805_FIRMWARE_REG      0x50
#define PCIE_BUS_SHIFT          20
#define PCIE_SLOT_SHIFT         15
#define PCIE_FUNC_SHIFT         12

static int
bcm_xhci_probe(device_t dev)
{
        phandle_t root;
        uint32_t device_id;

        device_id = pci_get_devid(dev);
        if (device_id != 0x34831106) /* VIA VL805 USB 3.0 controller. */
                return (ENXIO);

        /*
         * The VIA chip is not unique to the Pi, but we only want to use this
         * driver if the SoC is a Raspberry Pi 4. Walk the device tree to
         * discover if the system is a Pi 4.
         */
        root = OF_finddevice("/");
        if (root == -1)
                return (ENXIO);
        if (!ofw_bus_node_is_compatible(root, "raspberrypi,4-model-b"))
                return (ENXIO);

        /*
         * On the Pi 4, the VIA chip with the firmware-loading limitation is
         * soldered-on to a particular bus/slot/function. But, it's possible a
         * user could desolder the VIA chip, replace it with a pci-pci bridge,
         * then plug in a commodity VIA PCI-e card on the new bridge. In that
         * case we don't want to try to load the firmware to a commodity
         * expansion card.
         */
        if (pci_get_bus(dev) != 1 || pci_get_slot(dev) != 0 ||
            pci_get_function(dev) != 0 )
                return (ENXIO);

        device_set_desc(dev,
            "VL805 USB 3.0 controller (on the Raspberry Pi 4b)");

        return (BUS_PROBE_SPECIFIC);
}

static uint32_t
bcm_xhci_check_firmware(device_t dev, bool expect_loaded)
{
        uint32_t revision;
        bool loaded;

        revision = pci_read_config(dev, VL805_FIRMWARE_REG, 4);
        loaded = !(revision == 0 || revision == 0xffffffff);

        if (expect_loaded && !loaded)
                device_printf(dev, "warning: xhci firmware not found.\n");
        else if (bootverbose && !loaded)
                device_printf(dev, "note: xhci firmware not found.\n");
        else if (bootverbose)
                device_printf(dev,
                    "note: xhci firmware detected; firmware is revision %x.\n",
                     revision);

        if (!loaded)
                return 0;

        return (revision);
}

static void
bcm_xhci_install_xhci_firmware(device_t dev)
{
        uint32_t revision, dev_addr;
        int error;

        revision = bcm_xhci_check_firmware(dev, false);
        if (revision > 0) {
                /*
                 * With the pre-June 2020 boot firmware, it does not seem
                 * possible to reload already-installed xhci firmware.
                 */
                return;
        }

        /*
         * Notify the VideoCore gpu processor that it needs to reload the xhci
         * firmware into the xhci controller. This needs to happen after the pci
         * bridge topology is registered with the controller.
         */
        if (bootverbose)
                device_printf(dev, "note: installing xhci firmware.\n");

        dev_addr =
            pci_get_bus(dev)      << PCIE_BUS_SHIFT |
            pci_get_slot(dev)     << PCIE_SLOT_SHIFT |
            pci_get_function(dev) << PCIE_FUNC_SHIFT;

        error = bcm2835_mbox_notify_xhci_reset(dev_addr);
        if (error)
                device_printf(dev,
                    "warning: xhci firmware install failed (error %d).\n",
                    error);

        DELAY(1000);
        bcm_xhci_check_firmware(dev, true);

        return;
}

static int
bcm_xhci_attach(device_t dev)
{
        struct xhci_softc *sc;
        int error;

        sc = device_get_softc(dev);

        bcm_xhci_install_xhci_firmware(dev);

        error = xhci_pci_attach(dev);
        if (error)
                return (error);

        /* 32 bit DMA is a limitation of the PCI-e controller, not the VL805. */
        sc->sc_bus.dma_bits = 32;
        if (bootverbose)
                device_printf(dev, "note: switched to 32-bit DMA.\n");

        return (0);
}

/*
 * Device method table.
 */
static device_method_t bcm_xhci_methods[] = {
        /* Device interface. */
        DEVMETHOD(device_probe,                 bcm_xhci_probe),
        DEVMETHOD(device_attach,                bcm_xhci_attach),

        DEVMETHOD_END,
};

DEFINE_CLASS_1(bcm_xhci, bcm_xhci_driver, bcm_xhci_methods,
    sizeof(struct xhci_softc), xhci_pci_driver);

DRIVER_MODULE(bcm_xhci, pci, bcm_xhci_driver, 0, 0);
MODULE_DEPEND(bcm_xhci, usb, 1, 1, 1);
MODULE_DEPEND(bcm_xhci, pci, 1, 1, 1);
MODULE_DEPEND(bcm_xhci, xhci, 1, 1, 1);