root/drivers/usb/phy/phy-generic.c
// SPDX-License-Identifier: GPL-2.0+
/*
 * NOP USB transceiver for all USB transceiver which are either built-in
 * into USB IP or which are mostly autonomous.
 *
 * Copyright (C) 2009 Texas Instruments Inc
 * Author: Ajay Kumar Gupta <ajay.gupta@ti.com>
 *
 * Current status:
 *      This provides a "nop" transceiver for PHYs which are
 *      autonomous such as isp1504, isp1707, etc.
 */

#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/dma-mapping.h>
#include <linux/usb/gadget.h>
#include <linux/usb/otg.h>
#include <linux/usb/usb_phy_generic.h>
#include <linux/slab.h>
#include <linux/clk.h>
#include <linux/regulator/consumer.h>
#include <linux/property.h>
#include <linux/gpio/consumer.h>
#include <linux/delay.h>

#include "phy-generic.h"

#define VBUS_IRQ_FLAGS \
        (IRQF_SHARED | IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING | \
                IRQF_ONESHOT)

struct platform_device *usb_phy_generic_register(void)
{
        return platform_device_register_simple("usb_phy_generic",
                        PLATFORM_DEVID_AUTO, NULL, 0);
}
EXPORT_SYMBOL_GPL(usb_phy_generic_register);

void usb_phy_generic_unregister(struct platform_device *pdev)
{
        platform_device_unregister(pdev);
}
EXPORT_SYMBOL_GPL(usb_phy_generic_unregister);

static int nop_set_suspend(struct usb_phy *x, int suspend)
{
        struct usb_phy_generic *nop = dev_get_drvdata(x->dev);
        int ret = 0;

        if (suspend) {
                clk_disable_unprepare(nop->clk);
                if (!IS_ERR(nop->vcc) && !device_may_wakeup(x->dev))
                        ret = regulator_disable(nop->vcc);
        } else {
                if (!IS_ERR(nop->vcc) && !device_may_wakeup(x->dev))
                        ret = regulator_enable(nop->vcc);
                clk_prepare_enable(nop->clk);
        }

        return ret;
}

static void nop_reset(struct usb_phy_generic *nop)
{
        if (!nop->gpiod_reset)
                return;

        gpiod_set_value_cansleep(nop->gpiod_reset, 1);
        usleep_range(10000, 20000);
        gpiod_set_value_cansleep(nop->gpiod_reset, 0);
        usleep_range(10000, 30000);
}

/* interface to regulator framework */
static int nop_set_vbus(struct usb_otg *otg, bool enable)
{
        int ret = 0;
        struct usb_phy_generic *nop = dev_get_drvdata(otg->usb_phy->dev);

        if (!nop->vbus_draw)
                return 0;

        if (enable && !nop->vbus_draw_enabled) {
                ret = regulator_enable(nop->vbus_draw);
                if (ret)
                        nop->vbus_draw_enabled = false;
                else
                        nop->vbus_draw_enabled = true;

        } else if (!enable && nop->vbus_draw_enabled) {
                ret = regulator_disable(nop->vbus_draw);
                nop->vbus_draw_enabled = false;
        }
        return ret;
}


static irqreturn_t nop_gpio_vbus_thread(int irq, void *data)
{
        struct usb_phy_generic *nop = data;
        struct usb_otg *otg = nop->phy.otg;
        int vbus, status;

        vbus = gpiod_get_value(nop->gpiod_vbus);
        if ((vbus ^ nop->vbus) == 0)
                return IRQ_HANDLED;
        nop->vbus = vbus;

        if (vbus) {
                status = USB_EVENT_VBUS;
                otg->state = OTG_STATE_B_PERIPHERAL;
                nop->phy.last_event = status;

                atomic_notifier_call_chain(&nop->phy.notifier, status,
                                           otg->gadget);
        } else {
                status = USB_EVENT_NONE;
                otg->state = OTG_STATE_B_IDLE;
                nop->phy.last_event = status;

                atomic_notifier_call_chain(&nop->phy.notifier, status,
                                           otg->gadget);
        }
        return IRQ_HANDLED;
}

int usb_gen_phy_init(struct usb_phy *phy)
{
        struct usb_phy_generic *nop = dev_get_drvdata(phy->dev);
        int ret;

        if (!IS_ERR(nop->vcc)) {
                if (regulator_enable(nop->vcc))
                        dev_err(phy->dev, "Failed to enable power\n");
        }

        ret = clk_prepare_enable(nop->clk);
        if (ret)
                return ret;

        nop_reset(nop);

        return 0;
}
EXPORT_SYMBOL_GPL(usb_gen_phy_init);

void usb_gen_phy_shutdown(struct usb_phy *phy)
{
        struct usb_phy_generic *nop = dev_get_drvdata(phy->dev);

        gpiod_set_value_cansleep(nop->gpiod_reset, 1);

        clk_disable_unprepare(nop->clk);

        if (!IS_ERR(nop->vcc)) {
                if (regulator_disable(nop->vcc))
                        dev_err(phy->dev, "Failed to disable power\n");
        }
}
EXPORT_SYMBOL_GPL(usb_gen_phy_shutdown);

static int nop_set_peripheral(struct usb_otg *otg, struct usb_gadget *gadget)
{
        if (!otg)
                return -ENODEV;

        if (!gadget) {
                otg->gadget = NULL;
                return -ENODEV;
        }

        otg->gadget = gadget;
        if (otg->state == OTG_STATE_B_PERIPHERAL)
                atomic_notifier_call_chain(&otg->usb_phy->notifier,
                                           USB_EVENT_VBUS, otg->gadget);
        else
                otg->state = OTG_STATE_B_IDLE;
        return 0;
}

static int nop_set_host(struct usb_otg *otg, struct usb_bus *host)
{
        if (!otg)
                return -ENODEV;

        if (!host) {
                otg->host = NULL;
                return -ENODEV;
        }

        otg->host = host;
        return 0;
}

int usb_phy_gen_create_phy(struct device *dev, struct usb_phy_generic *nop)
{
        enum usb_phy_type type = USB_PHY_TYPE_USB2;
        int err = 0;
        u32 clk_rate = 0;

        device_property_read_u32(dev, "clock-frequency", &clk_rate);
        nop->gpiod_reset = devm_gpiod_get_optional(dev, "reset",
                                                   GPIOD_ASIS);
        err = PTR_ERR_OR_ZERO(nop->gpiod_reset);
        if (!err) {
                nop->gpiod_vbus = devm_gpiod_get_optional(dev,
                                                 "vbus-detect",
                                                 GPIOD_ASIS);
                err = PTR_ERR_OR_ZERO(nop->gpiod_vbus);
        }

        if (err)
                return dev_err_probe(dev, err,
                                     "Error requesting RESET or VBUS GPIO\n");
        if (nop->gpiod_reset)
                gpiod_direction_output(nop->gpiod_reset, 1);

        nop->phy.otg = devm_kzalloc(dev, sizeof(*nop->phy.otg),
                        GFP_KERNEL);
        if (!nop->phy.otg)
                return -ENOMEM;

        nop->clk = devm_clk_get_optional(dev, "main_clk");
        if (IS_ERR(nop->clk))
                return dev_err_probe(dev, PTR_ERR(nop->clk),
                                     "Can't get phy clock\n");

        if (clk_rate) {
                err = clk_set_rate(nop->clk, clk_rate);
                if (err)
                        return dev_err_probe(dev, err,
                                             "Error setting clock rate\n");
        }

        nop->vcc = devm_regulator_get_optional(dev, "vcc");
        if (IS_ERR(nop->vcc) && PTR_ERR(nop->vcc) != -ENODEV)
                return dev_err_probe(dev, PTR_ERR(nop->vcc),
                                     "could not get vcc regulator\n");

        nop->vbus_draw = devm_regulator_get_exclusive(dev, "vbus");
        if (PTR_ERR(nop->vbus_draw) == -ENODEV)
                nop->vbus_draw = NULL;
        if (IS_ERR(nop->vbus_draw))
                return dev_err_probe(dev, PTR_ERR(nop->vbus_draw),
                                     "could not get vbus regulator\n");

        nop->dev                = dev;
        nop->phy.dev            = nop->dev;
        nop->phy.label          = "nop-xceiv";
        nop->phy.set_suspend    = nop_set_suspend;
        nop->phy.type           = type;

        nop->phy.otg->state             = OTG_STATE_UNDEFINED;
        nop->phy.otg->usb_phy           = &nop->phy;
        nop->phy.otg->set_host          = nop_set_host;
        nop->phy.otg->set_peripheral    = nop_set_peripheral;
        nop->phy.otg->set_vbus          = nop_set_vbus;

        return 0;
}
EXPORT_SYMBOL_GPL(usb_phy_gen_create_phy);

static int usb_phy_generic_probe(struct platform_device *pdev)
{
        struct device *dev = &pdev->dev;
        struct usb_phy_generic  *nop;
        int err;

        nop = devm_kzalloc(dev, sizeof(*nop), GFP_KERNEL);
        if (!nop)
                return -ENOMEM;

        err = usb_phy_gen_create_phy(dev, nop);
        if (err)
                return err;

        if (nop->gpiod_vbus) {
                err = devm_request_threaded_irq(dev,
                                                gpiod_to_irq(nop->gpiod_vbus),
                                                NULL, nop_gpio_vbus_thread,
                                                VBUS_IRQ_FLAGS, "vbus_detect",
                                                nop);
                if (err)
                        return dev_err_probe(dev, err, "can't request irq %i\n",
                                             gpiod_to_irq(nop->gpiod_vbus));

                nop->phy.otg->state = gpiod_get_value(nop->gpiod_vbus) ?
                        OTG_STATE_B_PERIPHERAL : OTG_STATE_B_IDLE;
        }

        nop->phy.init           = usb_gen_phy_init;
        nop->phy.shutdown       = usb_gen_phy_shutdown;

        err = usb_add_phy_dev(&nop->phy);
        if (err)
                return dev_err_probe(dev, err, "can't register transceiver\n");

        platform_set_drvdata(pdev, nop);

        device_set_wakeup_capable(dev,
                                  device_property_read_bool(dev, "wakeup-source"));

        return 0;
}

static void usb_phy_generic_remove(struct platform_device *pdev)
{
        struct usb_phy_generic *nop = platform_get_drvdata(pdev);

        usb_remove_phy(&nop->phy);

        if (nop->vbus_draw && nop->vbus_draw_enabled)
                regulator_disable(nop->vbus_draw);
}

static const struct of_device_id nop_xceiv_dt_ids[] = {
        { .compatible = "usb-nop-xceiv" },
        { }
};

MODULE_DEVICE_TABLE(of, nop_xceiv_dt_ids);

static struct platform_driver usb_phy_generic_driver = {
        .probe          = usb_phy_generic_probe,
        .remove         = usb_phy_generic_remove,
        .driver         = {
                .name   = "usb_phy_generic",
                .of_match_table = nop_xceiv_dt_ids,
        },
};

static int __init usb_phy_generic_init(void)
{
        return platform_driver_register(&usb_phy_generic_driver);
}
subsys_initcall(usb_phy_generic_init);

static void __exit usb_phy_generic_exit(void)
{
        platform_driver_unregister(&usb_phy_generic_driver);
}
module_exit(usb_phy_generic_exit);

MODULE_ALIAS("platform:usb_phy_generic");
MODULE_AUTHOR("Texas Instruments Inc");
MODULE_DESCRIPTION("NOP USB Transceiver driver");
MODULE_LICENSE("GPL");