// SPDX-License-Identifier: GPL-2.0
/*
 * I/O Processor (IOP) ADB Driver
 * Written and (C) 1999 by Joshua M. Thompson (funaho@jurai.org)
 * Based on via-cuda.c by Paul Mackerras.
 *
 * 1999-07-01 (jmt) - First implementation for new driver architecture.
 *
 * 1999-07-31 (jmt) - First working version.
 */

#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/delay.h>
#include <linux/init.h>

#include <asm/macintosh.h>
#include <asm/macints.h>
#include <asm/mac_iop.h>
#include <asm/adb_iop.h>
#include <linux/unaligned.h>

#include <linux/adb.h>

static struct adb_request *current_req;
static struct adb_request *last_req;
static unsigned int autopoll_devs;
static u8 autopoll_addr;

static enum adb_iop_state {
        idle,
        sending,
        awaiting_reply
} adb_iop_state;

static void adb_iop_start(void);
static int adb_iop_probe(void);
static int adb_iop_init(void);
static int adb_iop_send_request(struct adb_request *, int);
static int adb_iop_write(struct adb_request *);
static int adb_iop_autopoll(int);
static void adb_iop_poll(void);
static int adb_iop_reset_bus(void);

/* ADB command byte structure */
#define ADDR_MASK       0xF0
#define OP_MASK         0x0C
#define TALK            0x0C

struct adb_driver adb_iop_driver = {
        .name         = "ISM IOP",
        .probe        = adb_iop_probe,
        .init         = adb_iop_init,
        .send_request = adb_iop_send_request,
        .autopoll     = adb_iop_autopoll,
        .poll         = adb_iop_poll,
        .reset_bus    = adb_iop_reset_bus
};

static void adb_iop_done(void)
{
        struct adb_request *req = current_req;

        adb_iop_state = idle;

        req->complete = 1;
        current_req = req->next;
        if (req->done)
                (*req->done)(req);

        if (adb_iop_state == idle)
                adb_iop_start();
}

/*
 * Completion routine for ADB commands sent to the IOP.
 *
 * This will be called when a packet has been successfully sent.
 */

static void adb_iop_complete(struct iop_msg *msg)
{
        unsigned long flags;

        local_irq_save(flags);

        adb_iop_state = awaiting_reply;

        local_irq_restore(flags);
}

/*
 * Listen for ADB messages from the IOP.
 *
 * This will be called when unsolicited IOP messages are received.
 * These IOP messages can carry ADB autopoll responses and also occur
 * after explicit ADB commands.
 */

static void adb_iop_listen(struct iop_msg *msg)
{
        struct adb_iopmsg *amsg = (struct adb_iopmsg *)msg->message;
        u8 addr = (amsg->cmd & ADDR_MASK) >> 4;
        u8 op = amsg->cmd & OP_MASK;
        unsigned long flags;
        bool req_done = false;

        local_irq_save(flags);

        /* Responses to Talk commands may be unsolicited as they are
         * produced when the IOP polls devices. They are mostly timeouts.
         */
        if (op == TALK && ((1 << addr) & autopoll_devs))
                autopoll_addr = addr;

        switch (amsg->flags & (ADB_IOP_EXPLICIT |
                               ADB_IOP_AUTOPOLL |
                               ADB_IOP_TIMEOUT)) {
        case ADB_IOP_EXPLICIT:
        case ADB_IOP_EXPLICIT | ADB_IOP_TIMEOUT:
                if (adb_iop_state == awaiting_reply) {
                        struct adb_request *req = current_req;

                        if (req->reply_expected) {
                                req->reply_len = amsg->count + 1;
                                memcpy(req->reply, &amsg->cmd, req->reply_len);
                        }

                        req_done = true;
                }
                break;
        case ADB_IOP_AUTOPOLL:
                if (((1 << addr) & autopoll_devs) &&
                    amsg->cmd == ADB_READREG(addr, 0))
                        adb_input(&amsg->cmd, amsg->count + 1, 1);
                break;
        }
        msg->reply[0] = autopoll_addr ? ADB_IOP_AUTOPOLL : 0;
        msg->reply[1] = 0;
        msg->reply[2] = autopoll_addr ? ADB_READREG(autopoll_addr, 0) : 0;
        iop_complete_message(msg);

        if (req_done)
                adb_iop_done();

        local_irq_restore(flags);
}

/*
 * Start sending an ADB packet, IOP style
 *
 * There isn't much to do other than hand the packet over to the IOP
 * after encapsulating it in an adb_iopmsg.
 */

static void adb_iop_start(void)
{
        struct adb_request *req;
        struct adb_iopmsg amsg;

        /* get the packet to send */
        req = current_req;
        if (!req)
                return;

        /* The IOP takes MacII-style packets, so strip the initial
         * ADB_PACKET byte.
         */
        amsg.flags = ADB_IOP_EXPLICIT;
        amsg.count = req->nbytes - 2;

        /* amsg.data immediately follows amsg.cmd, effectively making
         * &amsg.cmd a pointer to the beginning of a full ADB packet.
         */
        memcpy(&amsg.cmd, req->data + 1, req->nbytes - 1);

        req->sent = 1;
        adb_iop_state = sending;

        /* Now send it. The IOP manager will call adb_iop_complete
         * when the message has been sent.
         */
        iop_send_message(ADB_IOP, ADB_CHAN, req, sizeof(amsg), (__u8 *)&amsg,
                         adb_iop_complete);
}

static int adb_iop_probe(void)
{
        if (!iop_ism_present)
                return -ENODEV;
        return 0;
}

static int adb_iop_init(void)
{
        pr_info("adb: IOP ISM driver v0.4 for Unified ADB\n");
        iop_listen(ADB_IOP, ADB_CHAN, adb_iop_listen, "ADB");
        return 0;
}

static int adb_iop_send_request(struct adb_request *req, int sync)
{
        int err;

        err = adb_iop_write(req);
        if (err)
                return err;

        if (sync) {
                while (!req->complete)
                        adb_iop_poll();
        }
        return 0;
}

static int adb_iop_write(struct adb_request *req)
{
        unsigned long flags;

        if ((req->nbytes < 2) || (req->data[0] != ADB_PACKET)) {
                req->complete = 1;
                return -EINVAL;
        }

        req->next = NULL;
        req->sent = 0;
        req->complete = 0;
        req->reply_len = 0;

        local_irq_save(flags);

        if (current_req) {
                last_req->next = req;
                last_req = req;
        } else {
                current_req = req;
                last_req = req;
        }

        if (adb_iop_state == idle)
                adb_iop_start();

        local_irq_restore(flags);

        return 0;
}

static void adb_iop_set_ap_complete(struct iop_msg *msg)
{
        struct adb_iopmsg *amsg = (struct adb_iopmsg *)msg->message;

        autopoll_devs = get_unaligned_be16(amsg->data);
        if (autopoll_devs & (1 << autopoll_addr))
                return;
        autopoll_addr = autopoll_devs ? (ffs(autopoll_devs) - 1) : 0;
}

static int adb_iop_autopoll(int devs)
{
        struct adb_iopmsg amsg;
        unsigned long flags;
        unsigned int mask = (unsigned int)devs & 0xFFFE;

        local_irq_save(flags);

        amsg.flags = ADB_IOP_SET_AUTOPOLL | (mask ? ADB_IOP_AUTOPOLL : 0);
        amsg.count = 2;
        amsg.cmd = 0;
        put_unaligned_be16(mask, amsg.data);

        iop_send_message(ADB_IOP, ADB_CHAN, NULL, sizeof(amsg), (__u8 *)&amsg,
                         adb_iop_set_ap_complete);

        local_irq_restore(flags);

        return 0;
}

static void adb_iop_poll(void)
{
        iop_ism_irq_poll(ADB_IOP);
}

static int adb_iop_reset_bus(void)
{
        struct adb_request req;

        /* Command = 0, Address = ignored */
        adb_request(&req, NULL, ADBREQ_NOSEND, 1, ADB_BUSRESET);
        adb_iop_send_request(&req, 1);

        /* Don't want any more requests during the Global Reset low time. */
        mdelay(3);

        return 0;
}