/*
 * mtu3_dr.c - dual role switch and host glue layer
 *
 * Copyright (C) 2016 MediaTek Inc.
 *
 * Author: Chunfeng Yun <chunfeng.yun@mediatek.com>
 *
 * This software is licensed under the terms of the GNU General Public
 * License version 2, as published by the Free Software Foundation, and
 * may be copied, distributed, and modified under those terms.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 */

#include <linux/debugfs.h>
#include <linux/irq.h>
#include <linux/kernel.h>
#include <linux/of_device.h>
#include <linux/pinctrl/consumer.h>
#include <linux/seq_file.h>
#include <linux/uaccess.h>

#include "mtu3.h"
#include "mtu3_dr.h"

#define USB2_PORT 2
#define USB3_PORT 3

enum mtu3_vbus_id_state {
        MTU3_ID_FLOAT = 1,
        MTU3_ID_GROUND,
        MTU3_VBUS_OFF,
        MTU3_VBUS_VALID,
};

static void toggle_opstate(struct ssusb_mtk *ssusb)
{
        if (!ssusb->otg_switch.is_u3_drd) {
                mtu3_setbits(ssusb->mac_base, U3D_DEVICE_CONTROL, DC_SESSION);
                mtu3_setbits(ssusb->mac_base, U3D_POWER_MANAGEMENT, SOFT_CONN);
        }
}

/* only port0 supports dual-role mode */
static int ssusb_port0_switch(struct ssusb_mtk *ssusb,
        int version, bool tohost)
{
        void __iomem *ibase = ssusb->ippc_base;
        u32 value;

        dev_dbg(ssusb->dev, "%s (switch u%d port0 to %s)\n", __func__,
                version, tohost ? "host" : "device");

        if (version == USB2_PORT) {
                /* 1. power off and disable u2 port0 */
                value = mtu3_readl(ibase, SSUSB_U2_CTRL(0));
                value |= SSUSB_U2_PORT_PDN | SSUSB_U2_PORT_DIS;
                mtu3_writel(ibase, SSUSB_U2_CTRL(0), value);

                /* 2. power on, enable u2 port0 and select its mode */
                value = mtu3_readl(ibase, SSUSB_U2_CTRL(0));
                value &= ~(SSUSB_U2_PORT_PDN | SSUSB_U2_PORT_DIS);
                value = tohost ? (value | SSUSB_U2_PORT_HOST_SEL) :
                        (value & (~SSUSB_U2_PORT_HOST_SEL));
                mtu3_writel(ibase, SSUSB_U2_CTRL(0), value);
        } else {
                /* 1. power off and disable u3 port0 */
                value = mtu3_readl(ibase, SSUSB_U3_CTRL(0));
                value |= SSUSB_U3_PORT_PDN | SSUSB_U3_PORT_DIS;
                mtu3_writel(ibase, SSUSB_U3_CTRL(0), value);

                /* 2. power on, enable u3 port0 and select its mode */
                value = mtu3_readl(ibase, SSUSB_U3_CTRL(0));
                value &= ~(SSUSB_U3_PORT_PDN | SSUSB_U3_PORT_DIS);
                value = tohost ? (value | SSUSB_U3_PORT_HOST_SEL) :
                        (value & (~SSUSB_U3_PORT_HOST_SEL));
                mtu3_writel(ibase, SSUSB_U3_CTRL(0), value);
        }

        return 0;
}

static void switch_port_to_host(struct ssusb_mtk *ssusb)
{
        u32 check_clk = 0;

        dev_dbg(ssusb->dev, "%s\n", __func__);

        ssusb_port0_switch(ssusb, USB2_PORT, true);

        if (ssusb->otg_switch.is_u3_drd) {
                ssusb_port0_switch(ssusb, USB3_PORT, true);
                check_clk = SSUSB_U3_MAC_RST_B_STS;
        }

        ssusb_check_clocks(ssusb, check_clk);

        /* after all clocks are stable */
        toggle_opstate(ssusb);
}

static void switch_port_to_device(struct ssusb_mtk *ssusb)
{
        u32 check_clk = 0;

        dev_dbg(ssusb->dev, "%s\n", __func__);

        ssusb_port0_switch(ssusb, USB2_PORT, false);

        if (ssusb->otg_switch.is_u3_drd) {
                ssusb_port0_switch(ssusb, USB3_PORT, false);
                check_clk = SSUSB_U3_MAC_RST_B_STS;
        }

        ssusb_check_clocks(ssusb, check_clk);
}

int ssusb_set_vbus(struct otg_switch_mtk *otg_sx, int is_on)
{
        struct ssusb_mtk *ssusb =
                container_of(otg_sx, struct ssusb_mtk, otg_switch);
        struct regulator *vbus = otg_sx->vbus;
        int ret;

        /* vbus is optional */
        if (!vbus)
                return 0;

        dev_dbg(ssusb->dev, "%s: turn %s\n", __func__, is_on ? "on" : "off");

        if (is_on) {
                ret = regulator_enable(vbus);
                if (ret) {
                        dev_err(ssusb->dev, "vbus regulator enable failed\n");
                        return ret;
                }
        } else {
                regulator_disable(vbus);
        }

        return 0;
}

/*
 * switch to host: -> MTU3_VBUS_OFF --> MTU3_ID_GROUND
 * switch to device: -> MTU3_ID_FLOAT --> MTU3_VBUS_VALID
 */
static void ssusb_set_mailbox(struct otg_switch_mtk *otg_sx,
        enum mtu3_vbus_id_state status)
{
        struct ssusb_mtk *ssusb =
                container_of(otg_sx, struct ssusb_mtk, otg_switch);
        struct mtu3 *mtu = ssusb->u3d;

        dev_dbg(ssusb->dev, "mailbox state(%d)\n", status);

        switch (status) {
        case MTU3_ID_GROUND:
                switch_port_to_host(ssusb);
                ssusb_set_vbus(otg_sx, 1);
                ssusb->is_host = true;
                break;
        case MTU3_ID_FLOAT:
                ssusb->is_host = false;
                ssusb_set_vbus(otg_sx, 0);
                switch_port_to_device(ssusb);
                break;
        case MTU3_VBUS_OFF:
                mtu3_stop(mtu);
                pm_relax(ssusb->dev);
                break;
        case MTU3_VBUS_VALID:
                /* avoid suspend when works as device */
                pm_stay_awake(ssusb->dev);
                mtu3_start(mtu);
                break;
        default:
                dev_err(ssusb->dev, "invalid state\n");
        }
}

static int ssusb_id_notifier(struct notifier_block *nb,
        unsigned long event, void *ptr)
{
        struct otg_switch_mtk *otg_sx =
                container_of(nb, struct otg_switch_mtk, id_nb);

        if (event)
                ssusb_set_mailbox(otg_sx, MTU3_ID_GROUND);
        else
                ssusb_set_mailbox(otg_sx, MTU3_ID_FLOAT);

        return NOTIFY_DONE;
}

static int ssusb_vbus_notifier(struct notifier_block *nb,
        unsigned long event, void *ptr)
{
        struct otg_switch_mtk *otg_sx =
                container_of(nb, struct otg_switch_mtk, vbus_nb);

        if (event)
                ssusb_set_mailbox(otg_sx, MTU3_VBUS_VALID);
        else
                ssusb_set_mailbox(otg_sx, MTU3_VBUS_OFF);

        return NOTIFY_DONE;
}

static int ssusb_extcon_register(struct otg_switch_mtk *otg_sx)
{
        struct ssusb_mtk *ssusb =
                container_of(otg_sx, struct ssusb_mtk, otg_switch);
        struct extcon_dev *edev = otg_sx->edev;
        int ret;

        /* extcon is optional */
        if (!edev)
                return 0;

        otg_sx->vbus_nb.notifier_call = ssusb_vbus_notifier;
        ret = devm_extcon_register_notifier(ssusb->dev, edev, EXTCON_USB,
                                        &otg_sx->vbus_nb);
        if (ret < 0)
                dev_err(ssusb->dev, "failed to register notifier for USB\n");

        otg_sx->id_nb.notifier_call = ssusb_id_notifier;
        ret = devm_extcon_register_notifier(ssusb->dev, edev, EXTCON_USB_HOST,
                                        &otg_sx->id_nb);
        if (ret < 0)
                dev_err(ssusb->dev, "failed to register notifier for USB-HOST\n");

        dev_dbg(ssusb->dev, "EXTCON_USB: %d, EXTCON_USB_HOST: %d\n",
                extcon_get_state(edev, EXTCON_USB),
                extcon_get_state(edev, EXTCON_USB_HOST));

        /* default as host, switch to device mode if needed */
        if (extcon_get_state(edev, EXTCON_USB_HOST) == false)
                ssusb_set_mailbox(otg_sx, MTU3_ID_FLOAT);
        if (extcon_get_state(edev, EXTCON_USB) == true)
                ssusb_set_mailbox(otg_sx, MTU3_VBUS_VALID);

        return 0;
}

static void extcon_register_dwork(struct work_struct *work)
{
        struct delayed_work *dwork = to_delayed_work(work);
        struct otg_switch_mtk *otg_sx =
            container_of(dwork, struct otg_switch_mtk, extcon_reg_dwork);

        ssusb_extcon_register(otg_sx);
}

/*
 * We provide an interface via debugfs to switch between host and device modes
 * depending on user input.
 * This is useful in special cases, such as uses TYPE-A receptacle but also
 * wants to support dual-role mode.
 * It generates cable state changes by pulling up/down IDPIN and
 * notifies driver to switch mode by "extcon-usb-gpio".
 * NOTE: when use MICRO receptacle, should not enable this interface.
 */
static void ssusb_mode_manual_switch(struct ssusb_mtk *ssusb, int to_host)
{
        struct otg_switch_mtk *otg_sx = &ssusb->otg_switch;

        if (to_host)
                pinctrl_select_state(otg_sx->id_pinctrl, otg_sx->id_ground);
        else
                pinctrl_select_state(otg_sx->id_pinctrl, otg_sx->id_float);
}


static int ssusb_mode_show(struct seq_file *sf, void *unused)
{
        struct ssusb_mtk *ssusb = sf->private;

        seq_printf(sf, "current mode: %s(%s drd)\n(echo device/host)\n",
                ssusb->is_host ? "host" : "device",
                ssusb->otg_switch.manual_drd_enabled ? "manual" : "auto");

        return 0;
}

static int ssusb_mode_open(struct inode *inode, struct file *file)
{
        return single_open(file, ssusb_mode_show, inode->i_private);
}

static ssize_t ssusb_mode_write(struct file *file,
        const char __user *ubuf, size_t count, loff_t *ppos)
{
        struct seq_file *sf = file->private_data;
        struct ssusb_mtk *ssusb = sf->private;
        char buf[16];

        if (copy_from_user(&buf, ubuf, min_t(size_t, sizeof(buf) - 1, count)))
                return -EFAULT;

        if (!strncmp(buf, "host", 4) && !ssusb->is_host) {
                ssusb_mode_manual_switch(ssusb, 1);
        } else if (!strncmp(buf, "device", 6) && ssusb->is_host) {
                ssusb_mode_manual_switch(ssusb, 0);
        } else {
                dev_err(ssusb->dev, "wrong or duplicated setting\n");
                return -EINVAL;
        }

        return count;
}

static const struct file_operations ssusb_mode_fops = {
        .open = ssusb_mode_open,
        .write = ssusb_mode_write,
        .read = seq_read,
        .llseek = seq_lseek,
        .release = single_release,
};

static int ssusb_vbus_show(struct seq_file *sf, void *unused)
{
        struct ssusb_mtk *ssusb = sf->private;
        struct otg_switch_mtk *otg_sx = &ssusb->otg_switch;

        seq_printf(sf, "vbus state: %s\n(echo on/off)\n",
                regulator_is_enabled(otg_sx->vbus) ? "on" : "off");

        return 0;
}

static int ssusb_vbus_open(struct inode *inode, struct file *file)
{
        return single_open(file, ssusb_vbus_show, inode->i_private);
}

static ssize_t ssusb_vbus_write(struct file *file,
        const char __user *ubuf, size_t count, loff_t *ppos)
{
        struct seq_file *sf = file->private_data;
        struct ssusb_mtk *ssusb = sf->private;
        struct otg_switch_mtk *otg_sx = &ssusb->otg_switch;
        char buf[16];
        bool enable;

        if (copy_from_user(&buf, ubuf, min_t(size_t, sizeof(buf) - 1, count)))
                return -EFAULT;

        if (kstrtobool(buf, &enable)) {
                dev_err(ssusb->dev, "wrong setting\n");
                return -EINVAL;
        }

        ssusb_set_vbus(otg_sx, enable);

        return count;
}

static const struct file_operations ssusb_vbus_fops = {
        .open = ssusb_vbus_open,
        .write = ssusb_vbus_write,
        .read = seq_read,
        .llseek = seq_lseek,
        .release = single_release,
};

static void ssusb_debugfs_init(struct ssusb_mtk *ssusb)
{
        struct dentry *root;

        root = debugfs_create_dir(dev_name(ssusb->dev), usb_debug_root);
        if (!root) {
                dev_err(ssusb->dev, "create debugfs root failed\n");
                return;
        }
        ssusb->dbgfs_root = root;

        debugfs_create_file("mode", 0644, root, ssusb, &ssusb_mode_fops);
        debugfs_create_file("vbus", 0644, root, ssusb, &ssusb_vbus_fops);
}

static void ssusb_debugfs_exit(struct ssusb_mtk *ssusb)
{
        debugfs_remove_recursive(ssusb->dbgfs_root);
}

int ssusb_otg_switch_init(struct ssusb_mtk *ssusb)
{
        struct otg_switch_mtk *otg_sx = &ssusb->otg_switch;

        INIT_DELAYED_WORK(&otg_sx->extcon_reg_dwork, extcon_register_dwork);

        if (otg_sx->manual_drd_enabled)
                ssusb_debugfs_init(ssusb);

        /* It is enough to delay 1s for waiting for host initialization */
        schedule_delayed_work(&otg_sx->extcon_reg_dwork, HZ);

        return 0;
}

void ssusb_otg_switch_exit(struct ssusb_mtk *ssusb)
{
        struct otg_switch_mtk *otg_sx = &ssusb->otg_switch;

        cancel_delayed_work(&otg_sx->extcon_reg_dwork);

        if (otg_sx->manual_drd_enabled)
                ssusb_debugfs_exit(ssusb);
}