// SPDX-License-Identifier: GPL-2.0+
/*
 * vio driver interface to hvc_console.c
 *
 * This code was moved here to allow the remaining code to be reused as a
 * generic polling mode with semi-reliable transport driver core to the
 * console and tty subsystems.
 *
 *
 * Copyright (C) 2001 Anton Blanchard <anton@au.ibm.com>, IBM
 * Copyright (C) 2001 Paul Mackerras <paulus@au.ibm.com>, IBM
 * Copyright (C) 2004 Benjamin Herrenschmidt <benh@kernel.crashing.org>, IBM Corp.
 * Copyright (C) 2004 IBM Corporation
 *
 * Additional Author(s):
 *  Ryan S. Arnold <rsa@us.ibm.com>
 *
 * TODO:
 *
 *   - handle error in sending hvsi protocol packets
 *   - retry nego on subsequent sends ?
 */

#undef DEBUG

#include <linux/types.h>
#include <linux/init.h>
#include <linux/delay.h>
#include <linux/slab.h>
#include <linux/console.h>

#include <asm/hvconsole.h>
#include <asm/vio.h>
#include <asm/prom.h>
#include <asm/hvsi.h>
#include <asm/udbg.h>
#include <asm/machdep.h>

#include "hvc_console.h"

static const char hvc_driver_name[] = "hvc_console";

static const struct vio_device_id hvc_driver_table[] = {
        {"serial", "hvterm1"},
#ifndef HVC_OLD_HVSI
        {"serial", "hvterm-protocol"},
#endif
        { "", "" }
};

typedef enum hv_protocol {
        HV_PROTOCOL_RAW,
        HV_PROTOCOL_HVSI
} hv_protocol_t;

struct hvterm_priv {
        u32                     termno; /* HV term number */
        hv_protocol_t           proto;  /* Raw data or HVSI packets */
        struct hvsi_priv        hvsi;   /* HVSI specific data */
        spinlock_t              buf_lock;
        char                    buf[SIZE_VIO_GET_CHARS];
        int                     left;
        int                     offset;
};
static struct hvterm_priv *hvterm_privs[MAX_NR_HVC_CONSOLES];
/* For early boot console */
static struct hvterm_priv hvterm_priv0;

static int hvterm_raw_get_chars(uint32_t vtermno, char *buf, int count)
{
        struct hvterm_priv *pv = hvterm_privs[vtermno];
        unsigned long i;
        unsigned long flags;
        int got;

        if (WARN_ON(!pv))
                return 0;

        spin_lock_irqsave(&pv->buf_lock, flags);

        if (pv->left == 0) {
                pv->offset = 0;
                pv->left = hvc_get_chars(pv->termno, pv->buf, count);

                /*
                 * Work around a HV bug where it gives us a null
                 * after every \r.  -- paulus
                 */
                for (i = 1; i < pv->left; ++i) {
                        if (pv->buf[i] == 0 && pv->buf[i-1] == '\r') {
                                --pv->left;
                                if (i < pv->left) {
                                        memmove(&pv->buf[i], &pv->buf[i+1],
                                                pv->left - i);
                                }
                        }
                }
        }

        got = min(count, pv->left);
        memcpy(buf, &pv->buf[pv->offset], got);
        pv->offset += got;
        pv->left -= got;

        spin_unlock_irqrestore(&pv->buf_lock, flags);

        return got;
}

/**
 * hvterm_raw_put_chars: send characters to firmware for given vterm adapter
 * @vtermno: The virtual terminal number.
 * @buf: The characters to send. Because of the underlying hypercall in
 *       hvc_put_chars(), this buffer must be at least 16 bytes long, even if
 *       you are sending fewer chars.
 * @count: number of chars to send.
 */
static int hvterm_raw_put_chars(uint32_t vtermno, const char *buf, int count)
{
        struct hvterm_priv *pv = hvterm_privs[vtermno];

        if (WARN_ON(!pv))
                return 0;

        return hvc_put_chars(pv->termno, buf, count);
}

static const struct hv_ops hvterm_raw_ops = {
        .get_chars = hvterm_raw_get_chars,
        .put_chars = hvterm_raw_put_chars,
        .notifier_add = notifier_add_irq,
        .notifier_del = notifier_del_irq,
        .notifier_hangup = notifier_hangup_irq,
};

static int hvterm_hvsi_get_chars(uint32_t vtermno, char *buf, int count)
{
        struct hvterm_priv *pv = hvterm_privs[vtermno];

        if (WARN_ON(!pv))
                return 0;

        return hvsilib_get_chars(&pv->hvsi, buf, count);
}

static int hvterm_hvsi_put_chars(uint32_t vtermno, const char *buf, int count)
{
        struct hvterm_priv *pv = hvterm_privs[vtermno];

        if (WARN_ON(!pv))
                return 0;

        return hvsilib_put_chars(&pv->hvsi, buf, count);
}

static int hvterm_hvsi_open(struct hvc_struct *hp, int data)
{
        struct hvterm_priv *pv = hvterm_privs[hp->vtermno];
        int rc;

        pr_devel("HVSI@%x: open !\n", pv->termno);

        rc = notifier_add_irq(hp, data);
        if (rc)
                return rc;

        return hvsilib_open(&pv->hvsi, hp);
}

static void hvterm_hvsi_close(struct hvc_struct *hp, int data)
{
        struct hvterm_priv *pv = hvterm_privs[hp->vtermno];

        pr_devel("HVSI@%x: do close !\n", pv->termno);

        hvsilib_close(&pv->hvsi, hp);

        notifier_del_irq(hp, data);
}

void hvterm_hvsi_hangup(struct hvc_struct *hp, int data)
{
        struct hvterm_priv *pv = hvterm_privs[hp->vtermno];

        pr_devel("HVSI@%x: do hangup !\n", pv->termno);

        hvsilib_close(&pv->hvsi, hp);

        notifier_hangup_irq(hp, data);
}

static int hvterm_hvsi_tiocmget(struct hvc_struct *hp)
{
        struct hvterm_priv *pv = hvterm_privs[hp->vtermno];

        if (!pv)
                return -EINVAL;
        return pv->hvsi.mctrl;
}

static int hvterm_hvsi_tiocmset(struct hvc_struct *hp, unsigned int set,
                                unsigned int clear)
{
        struct hvterm_priv *pv = hvterm_privs[hp->vtermno];

        pr_devel("HVSI@%x: Set modem control, set=%x,clr=%x\n",
                 pv->termno, set, clear);

        if (set & TIOCM_DTR)
                hvsilib_write_mctrl(&pv->hvsi, 1);
        else if (clear & TIOCM_DTR)
                hvsilib_write_mctrl(&pv->hvsi, 0);

        return 0;
}

static const struct hv_ops hvterm_hvsi_ops = {
        .get_chars = hvterm_hvsi_get_chars,
        .put_chars = hvterm_hvsi_put_chars,
        .notifier_add = hvterm_hvsi_open,
        .notifier_del = hvterm_hvsi_close,
        .notifier_hangup = hvterm_hvsi_hangup,
        .tiocmget = hvterm_hvsi_tiocmget,
        .tiocmset = hvterm_hvsi_tiocmset,
};

static void udbg_hvc_putc(char c)
{
        int count = -1;
        unsigned char bounce_buffer[16];

        if (!hvterm_privs[0])
                return;

        if (c == '\n')
                udbg_hvc_putc('\r');

        do {
                switch(hvterm_privs[0]->proto) {
                case HV_PROTOCOL_RAW:
                        /*
                         * hvterm_raw_put_chars requires at least a 16-byte
                         * buffer, so go via the bounce buffer
                         */
                        bounce_buffer[0] = c;
                        count = hvterm_raw_put_chars(0, bounce_buffer, 1);
                        break;
                case HV_PROTOCOL_HVSI:
                        count = hvterm_hvsi_put_chars(0, &c, 1);
                        break;
                }
        } while(count == 0);
}

static int udbg_hvc_getc_poll(void)
{
        int rc = 0;
        char c;

        if (!hvterm_privs[0])
                return -1;

        switch(hvterm_privs[0]->proto) {
        case HV_PROTOCOL_RAW:
                rc = hvterm_raw_get_chars(0, &c, 1);
                break;
        case HV_PROTOCOL_HVSI:
                rc = hvterm_hvsi_get_chars(0, &c, 1);
                break;
        }
        if (!rc)
                return -1;
        return c;
}

static int udbg_hvc_getc(void)
{
        int ch;

        if (!hvterm_privs[0])
                return -1;

        for (;;) {
                ch = udbg_hvc_getc_poll();
                if (ch == -1) {
                        /* This shouldn't be needed...but... */
                        volatile unsigned long delay;
                        for (delay=0; delay < 2000000; delay++)
                                ;
                } else {
                        return ch;
                }
        }
}

static int hvc_vio_probe(struct vio_dev *vdev,
                                   const struct vio_device_id *id)
{
        const struct hv_ops *ops;
        struct hvc_struct *hp;
        struct hvterm_priv *pv;
        hv_protocol_t proto;
        int i, termno = -1;

        /* probed with invalid parameters. */
        if (!vdev || !id)
                return -EPERM;

        if (of_device_is_compatible(vdev->dev.of_node, "hvterm1")) {
                proto = HV_PROTOCOL_RAW;
                ops = &hvterm_raw_ops;
        } else if (of_device_is_compatible(vdev->dev.of_node, "hvterm-protocol")) {
                proto = HV_PROTOCOL_HVSI;
                ops = &hvterm_hvsi_ops;
        } else {
                pr_err("hvc_vio: Unknown protocol for %pOF\n", vdev->dev.of_node);
                return -ENXIO;
        }

        pr_devel("hvc_vio_probe() device %pOF, using %s protocol\n",
                 vdev->dev.of_node,
                 proto == HV_PROTOCOL_RAW ? "raw" : "hvsi");

        /* Is it our boot one ? */
        if (hvterm_privs[0] == &hvterm_priv0 &&
            vdev->unit_address == hvterm_priv0.termno) {
                pv = hvterm_privs[0];
                termno = 0;
                pr_devel("->boot console, using termno 0\n");
        }
        /* nope, allocate a new one */
        else {
                for (i = 0; i < MAX_NR_HVC_CONSOLES && termno < 0; i++)
                        if (!hvterm_privs[i])
                                termno = i;
                pr_devel("->non-boot console, using termno %d\n", termno);
                if (termno < 0)
                        return -ENODEV;
                pv = kzalloc(sizeof(struct hvterm_priv), GFP_KERNEL);
                if (!pv)
                        return -ENOMEM;
                pv->termno = vdev->unit_address;
                pv->proto = proto;
                spin_lock_init(&pv->buf_lock);
                hvterm_privs[termno] = pv;
                hvsilib_init(&pv->hvsi, hvc_get_chars, hvc_put_chars,
                             pv->termno, 0);
        }

        hp = hvc_alloc(termno, vdev->irq, ops, MAX_VIO_PUT_CHARS);
        if (IS_ERR(hp))
                return PTR_ERR(hp);
        dev_set_drvdata(&vdev->dev, hp);

        /* register udbg if it's not there already for console 0 */
        if (hp->index == 0 && !udbg_putc) {
                udbg_putc = udbg_hvc_putc;
                udbg_getc = udbg_hvc_getc;
                udbg_getc_poll = udbg_hvc_getc_poll;
        }

        return 0;
}

static struct vio_driver hvc_vio_driver = {
        .id_table       = hvc_driver_table,
        .probe          = hvc_vio_probe,
        .name           = hvc_driver_name,
        .driver = {
                .suppress_bind_attrs    = true,
        },
};

static int __init hvc_vio_init(void)
{
        int rc;

        /* Register as a vio device to receive callbacks */
        rc = vio_register_driver(&hvc_vio_driver);

        return rc;
}
device_initcall(hvc_vio_init); /* after drivers/tty/hvc/hvc_console.c */

void __init hvc_vio_init_early(void)
{
        const __be32 *termno;
        const struct hv_ops *ops;

        /* find the boot console from /chosen/stdout */
        /* Check if it's a virtual terminal */
        if (!of_node_name_prefix(of_stdout, "vty"))
                return;
        termno = of_get_property(of_stdout, "reg", NULL);
        if (termno == NULL)
                return;
        hvterm_priv0.termno = of_read_number(termno, 1);
        spin_lock_init(&hvterm_priv0.buf_lock);
        hvterm_privs[0] = &hvterm_priv0;

        /* Check the protocol */
        if (of_device_is_compatible(of_stdout, "hvterm1")) {
                hvterm_priv0.proto = HV_PROTOCOL_RAW;
                ops = &hvterm_raw_ops;
        }
        else if (of_device_is_compatible(of_stdout, "hvterm-protocol")) {
                hvterm_priv0.proto = HV_PROTOCOL_HVSI;
                ops = &hvterm_hvsi_ops;
                hvsilib_init(&hvterm_priv0.hvsi, hvc_get_chars, hvc_put_chars,
                             hvterm_priv0.termno, 1);
                /* HVSI, perform the handshake now */
                hvsilib_establish(&hvterm_priv0.hvsi);
        } else
                return;
        udbg_putc = udbg_hvc_putc;
        udbg_getc = udbg_hvc_getc;
        udbg_getc_poll = udbg_hvc_getc_poll;
#ifdef HVC_OLD_HVSI
        /* When using the old HVSI driver don't register the HVC
         * backend for HVSI, only do udbg
         */
        if (hvterm_priv0.proto == HV_PROTOCOL_HVSI)
                return;
#endif
        /* Check whether the user has requested a different console. */
        if (!strstr(boot_command_line, "console="))
                add_preferred_console("hvc", 0, NULL);
        hvc_instantiate(0, 0, ops);
}

/* call this from early_init() for a working debug console on
 * vterm capable LPAR machines
 */
#ifdef CONFIG_PPC_EARLY_DEBUG_LPAR
void __init udbg_init_debug_lpar(void)
{
        /*
         * If we're running as a hypervisor then we definitely can't call the
         * hypervisor to print debug output (we *are* the hypervisor), so don't
         * register if we detect that MSR_HV=1.
         */
        if (mfmsr() & MSR_HV)
                return;

        hvterm_privs[0] = &hvterm_priv0;
        hvterm_priv0.termno = 0;
        hvterm_priv0.proto = HV_PROTOCOL_RAW;
        spin_lock_init(&hvterm_priv0.buf_lock);
        udbg_putc = udbg_hvc_putc;
        udbg_getc = udbg_hvc_getc;
        udbg_getc_poll = udbg_hvc_getc_poll;
}
#endif /* CONFIG_PPC_EARLY_DEBUG_LPAR */

#ifdef CONFIG_PPC_EARLY_DEBUG_LPAR_HVSI
void __init udbg_init_debug_lpar_hvsi(void)
{
        /* See comment above in udbg_init_debug_lpar() */
        if (mfmsr() & MSR_HV)
                return;

        hvterm_privs[0] = &hvterm_priv0;
        hvterm_priv0.termno = CONFIG_PPC_EARLY_DEBUG_HVSI_VTERMNO;
        hvterm_priv0.proto = HV_PROTOCOL_HVSI;
        spin_lock_init(&hvterm_priv0.buf_lock);
        udbg_putc = udbg_hvc_putc;
        udbg_getc = udbg_hvc_getc;
        udbg_getc_poll = udbg_hvc_getc_poll;
        hvsilib_init(&hvterm_priv0.hvsi, hvc_get_chars, hvc_put_chars,
                     hvterm_priv0.termno, 1);
        hvsilib_establish(&hvterm_priv0.hvsi);
}
#endif /* CONFIG_PPC_EARLY_DEBUG_LPAR_HVSI */