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/*

 * Device driver for the via-cuda on Apple Powermacs.

 *

 * The VIA (versatile interface adapter) interfaces to the CUDA,

 * a 6805 microprocessor core which controls the ADB (Apple Desktop

 * Bus) which connects to the keyboard and mouse.  The CUDA also

 * controls system power and the RTC (real time clock) chip.

 *

 * Copyright (C) 1996 Paul Mackerras.

 */

#include <stdarg.h>

#include <linux/config.h>

#include <linux/types.h>

#include <linux/errno.h>

#include <linux/kernel.h>

#include <linux/delay.h>

#include <linux/sched.h>

#include <linux/adb.h>

#include <linux/cuda.h>

#include <linux/spinlock.h>

#ifdef CONFIG_PPC

#include <asm/prom.h>

#include <asm/machdep.h>

#else

#include <asm/macintosh.h>

#include <asm/macints.h>

#include <asm/machw.h>

#include <asm/mac_via.h>

#endif

#include <asm/io.h>

#include <asm/system.h>

#include <linux/init.h>

static volatile unsigned char *via;

static spinlock_t cuda_lock = SPIN_LOCK_UNLOCKED;

#ifdef CONFIG_MAC

#define CUDA_IRQ IRQ_MAC_ADB

#define __openfirmware

#else

#define CUDA_IRQ vias->intrs[0].line

#endif

/* VIA registers - spaced 0x200 bytes apart */

#define RS              0x200           /* skip between registers */

#define B               0                /* B-side data */

#define A               RS              /* A-side data */

#define DIRB            (2*RS)          /* B-side direction (1=output) */

#define DIRA            (3*RS)          /* A-side direction (1=output) */

#define T1CL            (4*RS)          /* Timer 1 ctr/latch (low 8 bits) */

#define T1CH            (5*RS)          /* Timer 1 counter (high 8 bits) */

#define T1LL            (6*RS)          /* Timer 1 latch (low 8 bits) */

#define T1LH            (7*RS)          /* Timer 1 latch (high 8 bits) */

#define T2CL            (8*RS)          /* Timer 2 ctr/latch (low 8 bits) */

#define T2CH            (9*RS)          /* Timer 2 counter (high 8 bits) */

#define SR              (10*RS)         /* Shift register */

#define ACR             (11*RS)         /* Auxiliary control register */

#define PCR             (12*RS)         /* Peripheral control register */

#define IFR             (13*RS)         /* Interrupt flag register */

#define IER             (14*RS)         /* Interrupt enable register */

#define ANH             (15*RS)         /* A-side data, no handshake */

/* Bits in B data register: all active low */

#define TREQ            0x08            /* Transfer request (input) */

#define TACK            0x10            /* Transfer acknowledge (output) */

#define TIP             0x20            /* Transfer in progress (output) */

/* Bits in ACR */

#define SR_CTRL         0x1c            /* Shift register control bits */

#define SR_EXT          0x0c            /* Shift on external clock */

#define SR_OUT          0x10            /* Shift out if 1 */

/* Bits in IFR and IER */

#define IER_SET         0x80            /* set bits in IER */

#define IER_CLR         0                /* clear bits in IER */

#define SR_INT          0x04            /* Shift register full/empty */

static enum cuda_state {

    idle,

    sent_first_byte,

    sending,

    reading,

    read_done,

    awaiting_reply

} cuda_state;

static struct adb_request *current_req;

static struct adb_request *last_req;

static unsigned char cuda_rbuf[16];

static unsigned char *reply_ptr;

static int reading_reply;

static int data_index;

#ifdef CONFIG_PPC

static struct device_node *vias;

#endif

static int cuda_fully_inited = 0;

#ifdef CONFIG_ADB

static int cuda_probe(void);

static int cuda_init(void);

static int cuda_send_request(struct adb_request *req, int sync);

static int cuda_adb_autopoll(int devs);

static int cuda_reset_adb_bus(void);

#endif /* CONFIG_ADB */

static int cuda_init_via(void);

static void cuda_start(void);

static void cuda_interrupt(int irq, void *arg, struct pt_regs *regs);

static void cuda_input(unsigned char *buf, int nb, struct pt_regs *regs);

void cuda_poll(void);

static int cuda_write(struct adb_request *req);

int cuda_request(struct adb_request *req,

                 void (*done)(struct adb_request *), int nbytes, ...);

#ifdef CONFIG_ADB

struct adb_driver via_cuda_driver = {

        "CUDA",

        cuda_probe,

        cuda_init,

        cuda_send_request,

        cuda_adb_autopoll,

        cuda_poll,

        cuda_reset_adb_bus

};

#endif /* CONFIG_ADB */

#ifdef CONFIG_PPC

int __init

find_via_cuda(void)

{

    int err;

    struct adb_request req;

    if (vias != 0)

        return 1;

    vias = find_devices("via-cuda");

    if (vias == 0)

        return 0;

    if (vias->next != 0)

        printk(KERN_WARNING "Warning: only using 1st via-cuda\n");

#if 0

    { int i;

    printk("find_via_cuda: node = %p, addrs =", vias->node);

    for (i = 0; i < vias->n_addrs; ++i)

        printk(" %x(%x)", vias->addrs[i].address, vias->addrs[i].size);

    printk(", intrs =");

    for (i = 0; i < vias->n_intrs; ++i)

        printk(" %x", vias->intrs[i].line);

    printk("\n"); }

#endif

    if (vias->n_addrs != 1 || vias->n_intrs != 1) {

        printk(KERN_ERR "via-cuda: expecting 1 address (%d) and 1 interrupt (%d)\n",

               vias->n_addrs, vias->n_intrs);

        if (vias->n_addrs < 1 || vias->n_intrs < 1)

            return 0;

    }

    via = (volatile unsigned char *) ioremap(vias->addrs->address, 0x2000);

    cuda_state = idle;

    sys_ctrler = SYS_CTRLER_CUDA;

    err = cuda_init_via();

    if (err) {

        printk(KERN_ERR "cuda_init_via() failed\n");

        via = NULL;

        return 0;

    }

    /* Clear and enable interrupts, but only on PPC. On 68K it's done  */

    /* for us by the main VIA driver in arch/m68k/mac/via.c        */

#ifndef CONFIG_MAC

    out_8(&via[IFR], 0x7f);     /* clear interrupts by writing 1s */

    out_8(&via[IER], IER_SET|SR_INT); /* enable interrupt from SR */

#endif

    /* enable autopoll */

    cuda_request(&req, NULL, 3, CUDA_PACKET, CUDA_AUTOPOLL, 1);

    while (!req.complete)

        cuda_poll();

    return 1;

}

#endif /* CONFIG_PPC */

int __init

via_cuda_start(void)

{

    if (via == NULL)

        return -ENODEV;

#ifdef CONFIG_PPC

    request_OF_resource(vias, 0, NULL);

#endif

    if (request_irq(CUDA_IRQ, cuda_interrupt, 0, "ADB", cuda_interrupt)) {

        printk(KERN_ERR "cuda_init: can't get irq %d\n", CUDA_IRQ);

        return -EAGAIN;

    }

    printk("Macintosh CUDA driver v0.5 for Unified ADB.\n");

    cuda_fully_inited = 1;

    return 0;

}

#ifdef CONFIG_ADB

static int

cuda_probe()

{

#ifdef CONFIG_PPC

    if (sys_ctrler != SYS_CTRLER_CUDA)

        return -ENODEV;

#else

    if (macintosh_config->adb_type != MAC_ADB_CUDA)

        return -ENODEV;

    via = via1;

#endif

    return 0;

}

static int __init

cuda_init(void)

{

#ifdef CONFIG_PPC

    if (via == NULL)

        return -ENODEV;

    return 0;

#else 

    int err = cuda_init_via();

    if (err) {

        printk(KERN_ERR "cuda_init_via() failed\n");

        return -ENODEV;

    }

    return via_cuda_start();

#endif

}

#endif /* CONFIG_ADB */

#define WAIT_FOR(cond, what)                                    \

    do {                                                        \

        int x;                                                  \

        for (x = 1000; !(cond); --x) {                          \

            if (x == 0) {                                        \

                printk("Timeout waiting for " what "\n");       \

                return -ENXIO;                                  \

            }                                                   \

            udelay(100);                                        \

        }                                                       \

    } while (0)

static int

cuda_init_via()

{

    out_8(&via[DIRB], (in_8(&via[DIRB]) | TACK | TIP) & ~TREQ); /* TACK & TIP out */

    out_8(&via[B], in_8(&via[B]) | TACK | TIP);                 /* negate them */

    out_8(&via[ACR] ,(in_8(&via[ACR]) & ~SR_CTRL) | SR_EXT);    /* SR data in */

    (void)in_8(&via[SR]);                                               /* clear any left-over data */

#ifndef CONFIG_MAC

    out_8(&via[IER], 0x7f);                                     /* disable interrupts from VIA */

    (void)in_8(&via[IER]);

#endif

    /* delay 4ms and then clear any pending interrupt */

    mdelay(4);

    (void)in_8(&via[SR]);

    out_8(&via[IFR], in_8(&via[IFR]) & 0x7f);

    /* sync with the CUDA - assert TACK without TIP */

    out_8(&via[B], in_8(&via[B]) & ~TACK);

    /* wait for the CUDA to assert TREQ in response */

    WAIT_FOR((in_8(&via[B]) & TREQ) == 0, "CUDA response to sync");

    /* wait for the interrupt and then clear it */

    WAIT_FOR(in_8(&via[IFR]) & SR_INT, "CUDA response to sync (2)");

    (void)in_8(&via[SR]);

    out_8(&via[IFR], in_8(&via[IFR]) & 0x7f);

    /* finish the sync by negating TACK */

    out_8(&via[B], in_8(&via[B]) | TACK);

    /* wait for the CUDA to negate TREQ and the corresponding interrupt */

    WAIT_FOR(in_8(&via[B]) & TREQ, "CUDA response to sync (3)");

    WAIT_FOR(in_8(&via[IFR]) & SR_INT, "CUDA response to sync (4)");

    (void)in_8(&via[SR]);

    out_8(&via[IFR], in_8(&via[IFR]) & 0x7f);

    out_8(&via[B], in_8(&via[B]) | TIP);        /* should be unnecessary */

    return 0;

}

#ifdef CONFIG_ADB

/* Send an ADB command */

static int

cuda_send_request(struct adb_request *req, int sync)

{

    int i;

    if ((via == NULL) || !cuda_fully_inited) {

        req->complete = 1;

        return -ENXIO;

    }

    req->reply_expected = 1;

    i = cuda_write(req);

    if (i)

        return i;

    if (sync) {

        while (!req->complete)

            cuda_poll();

    }

    return 0;

}

/* Enable/disable autopolling */

static int

cuda_adb_autopoll(int devs)

{

    struct adb_request req;

    if ((via == NULL) || !cuda_fully_inited)

        return -ENXIO;

    cuda_request(&req, NULL, 3, CUDA_PACKET, CUDA_AUTOPOLL, (devs? 1: 0));

    while (!req.complete)

        cuda_poll();

    return 0;

}

/* Reset adb bus - how do we do this?? */

static int

cuda_reset_adb_bus(void)

{

    struct adb_request req;

    if ((via == NULL) || !cuda_fully_inited)

        return -ENXIO;

    cuda_request(&req, NULL, 2, ADB_PACKET, 0);          /* maybe? */

    while (!req.complete)

        cuda_poll();

    return 0;

}

#endif /* CONFIG_ADB */

/* Construct and send a cuda request */

int

cuda_request(struct adb_request *req, void (*done)(struct adb_request *),

             int nbytes, ...)

{

    va_list list;

    int i;

    if (via == NULL) {

        req->complete = 1;

        return -ENXIO;

    }

    req->nbytes = nbytes;

    req->done = done;

    va_start(list, nbytes);

    for (i = 0; i < nbytes; ++i)

        req->data[i] = va_arg(list, int);

    va_end(list);

    req->reply_expected = 1;

    return cuda_write(req);

}

static int

cuda_write(struct adb_request *req)

{

    unsigned long flags;

    if (req->nbytes < 2 || req->data[0] > CUDA_PACKET) {

        req->complete = 1;

        return -EINVAL;

    }

    req->next = 0;

    req->sent = 0;

    req->complete = 0;

    req->reply_len = 0;

    spin_lock_irqsave(&cuda_lock, flags);

    if (current_req != 0) {

        last_req->next = req;

        last_req = req;

    } else {

        current_req = req;

        last_req = req;

        if (cuda_state == idle)

            cuda_start();

    }

    spin_unlock_irqrestore(&cuda_lock, flags);

    return 0;

}

static void

cuda_start()

{

    struct adb_request *req;

    /* assert cuda_state == idle */

    /* get the packet to send */

    req = current_req;

    if (req == 0)

        return;

    if ((in_8(&via[B]) & TREQ) == 0)

        return;                 /* a byte is coming in from the CUDA */

    /* set the shift register to shift out and send a byte */

    out_8(&via[ACR], in_8(&via[ACR]) | SR_OUT);

    out_8(&via[SR], req->data[0]);

    out_8(&via[B], in_8(&via[B]) & ~TIP);

    cuda_state = sent_first_byte;

}

void

cuda_poll()

{

    unsigned long flags;

    /* cuda_interrupt only takes a normal lock, we disable

     * interrupts here to avoid re-entering and thus deadlocking.

     * An option would be to disable only the IRQ source with

     * disable_irq(), would that work on m68k ? --BenH

     */

    local_irq_save(flags);

    cuda_interrupt(0, 0, 0);

    local_irq_restore(flags);

}

static void

cuda_interrupt(int irq, void *arg, struct pt_regs *regs)

{

    int status;

    struct adb_request *req = NULL;

    unsigned char ibuf[16];

    int ibuf_len = 0;

    int complete = 0;

    unsigned char virq;

    spin_lock(&cuda_lock);

    virq = in_8(&via[IFR]) & 0x7f;

    out_8(&via[IFR], virq);

    if ((virq & SR_INT) == 0) {

        spin_unlock(&cuda_lock);

        return;

    }

    status = (~in_8(&via[B]) & (TIP|TREQ)) | (in_8(&via[ACR]) & SR_OUT);

    /* printk("cuda_interrupt: state=%d status=%x\n", cuda_state, status); */

    switch (cuda_state) {

    case idle:

        /* CUDA has sent us the first byte of data - unsolicited */

        if (status != TREQ)

            printk("cuda: state=idle, status=%x\n", status);

        (void)in_8(&via[SR]);

        out_8(&via[B], in_8(&via[B]) & ~TIP);

        cuda_state = reading;

        reply_ptr = cuda_rbuf;

        reading_reply = 0;

        break;

    case awaiting_reply:

        /* CUDA has sent us the first byte of data of a reply */

        if (status != TREQ)

            printk("cuda: state=awaiting_reply, status=%x\n", status);

        (void)in_8(&via[SR]);

        out_8(&via[B], in_8(&via[B]) & ~TIP);

        cuda_state = reading;

        reply_ptr = current_req->reply;

        reading_reply = 1;

        break;

    case sent_first_byte:

        if (status == TREQ + TIP + SR_OUT) {

            /* collision */

            out_8(&via[ACR], in_8(&via[ACR]) & ~SR_OUT);

            (void)in_8(&via[SR]);

            out_8(&via[B], in_8(&via[B]) | TIP | TACK);

            cuda_state = idle;

        } else {

            /* assert status == TIP + SR_OUT */

            if (status != TIP + SR_OUT)

                printk("cuda: state=sent_first_byte status=%x\n", status);

            out_8(&via[SR], current_req->data[1]);

            out_8(&via[B], in_8(&via[B]) ^ TACK);

            data_index = 2;

            cuda_state = sending;

        }

        break;

    case sending:

        req = current_req;

        if (data_index >= req->nbytes) {

            out_8(&via[ACR], in_8(&via[ACR]) & ~SR_OUT);

            (void)in_8(&via[SR]);

            out_8(&via[B], in_8(&via[B]) | TACK | TIP);

            req->sent = 1;

            if (req->reply_expected) {

                cuda_state = awaiting_reply;

            } else {

                current_req = req->next;

                complete = 1;

                /* not sure about this */

                cuda_state = idle;

                cuda_start();

            }

        } else {

            out_8(&via[SR], req->data[data_index++]);

            out_8(&via[B], in_8(&via[B]) ^ TACK);

        }

        break;

    case reading:

        *reply_ptr++ = in_8(&via[SR]);

        if (status == TIP) {

            /* that's all folks */

            out_8(&via[B], in_8(&via[B]) | TACK | TIP);

            cuda_state = read_done;

        } else {

            /* assert status == TIP | TREQ */

            if (status != TIP + TREQ)

                printk("cuda: state=reading status=%x\n", status);

            out_8(&via[B], in_8(&via[B]) ^ TACK);

        }

        break;

    case read_done:

        (void)in_8(&via[SR]);

        if (reading_reply) {

            req = current_req;

            req->reply_len = reply_ptr - req->reply;

            if (req->data[0] == ADB_PACKET) {

                /* Have to adjust the reply from ADB commands */

                if (req->reply_len <= 2 || (req->reply[1] & 2) != 0) {

                    /* the 0x2 bit indicates no response */

                    req->reply_len = 0;

                } else {

                    /* leave just the command and result bytes in the reply */

                    req->reply_len -= 2;

                    memmove(req->reply, req->reply + 2, req->reply_len);

                }

            }

            current_req = req->next;

            complete = 1;

        } else {

            /* This is tricky. We must break the spinlock to call

             * cuda_input. However, doing so means we might get

             * re-entered from another CPU getting an interrupt

             * or calling cuda_poll(). I ended up using the stack

             * (it's only for 16 bytes) and moving the actual

             * call to cuda_input to outside of the lock.

             */

            ibuf_len = reply_ptr - cuda_rbuf;

            memcpy(ibuf, cuda_rbuf, ibuf_len);

        }

        if (status == TREQ) {

            out_8(&via[B], in_8(&via[B]) & ~TIP);

            cuda_state = reading;

            reply_ptr = cuda_rbuf;

            reading_reply = 0;

        } else {

            cuda_state = idle;

            cuda_start();

        }

        break;

    default:

        printk("cuda_interrupt: unknown cuda_state %d?\n", cuda_state);

    }

    spin_unlock(&cuda_lock);

    if (complete && req) {

        void (*done)(struct adb_request *) = req->done;

        mb();

        req->complete = 1;

        /* Here, we assume that if the request has a done member, the

         * struct request will survive to setting req->complete to 1

         */

        if (done)

                (*done)(req);

    }

    if (ibuf_len)

        cuda_input(ibuf, ibuf_len, regs);

}

static void

cuda_input(unsigned char *buf, int nb, struct pt_regs *regs)

{

    int i;

    switch (buf[0]) {

    case ADB_PACKET:

#ifdef CONFIG_XMON

        if (nb == 5 && buf[2] == 0x2c) {

            extern int xmon_wants_key, xmon_adb_keycode;

            if (xmon_wants_key) {

                xmon_adb_keycode = buf[3];

                return;

            }

        }

#endif /* CONFIG_XMON */

#ifdef CONFIG_ADB

        adb_input(buf+2, nb-2, regs, buf[1] & 0x40);

#endif /* CONFIG_ADB */

        break;

    default:

        printk("data from cuda (%d bytes):", nb);

        for (i = 0; i < nb; ++i)

            printk(" %.2x", buf[i]);

        printk("\n");

    }

}