low_i2c.c

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/*
 * arch/powerpc/platforms/powermac/low_i2c.c
 *
 *  Copyright (C) 2003-2005 Ben. Herrenschmidt ([email protected])
 *
 *  This program is free software; you can redistribute it and/or
 *  modify it under the terms of the GNU General Public License
 *  as published by the Free Software Foundation; either version
 *  2 of the License, or (at your option) any later version.
 *
 * The linux i2c layer isn't completely suitable for our needs for various
 * reasons ranging from too late initialisation to semantics not perfectly
 * matching some requirements of the apple platform functions etc...
 *
 * This file thus provides a simple low level unified i2c interface for
 * powermac that covers the various types of i2c busses used in Apple machines.
 * For now, keywest, PMU and SMU, though we could add Cuda, or other bit
 * banging busses found on older chipstes in earlier machines if we ever need
 * one of them.
 *
 * The drivers in this file are synchronous/blocking. In addition, the
 * keywest one is fairly slow due to the use of msleep instead of interrupts
 * as the interrupt is currently used by i2c-keywest. In the long run, we
 * might want to get rid of those high-level interfaces to linux i2c layer
 * either completely (converting all drivers) or replacing them all with a
 * single stub driver on top of this one. Once done, the interrupt will be
 * available for our use.
 */

#undef DEBUG
#undef DEBUG_LOW

#include <linux/types.h>
#include <linux/sched.h>
#include <linux/init.h>
#include <linux/export.h>
#include <linux/adb.h>
#include <linux/pmu.h>
#include <linux/delay.h>
#include <linux/completion.h>
#include <linux/platform_device.h>
#include <linux/interrupt.h>
#include <linux/timer.h>
#include <linux/mutex.h>
#include <linux/i2c.h>
#include <linux/slab.h>
#include <asm/keylargo.h>
#include <asm/uninorth.h>
#include <asm/io.h>
#include <asm/prom.h>
#include <asm/machdep.h>
#include <asm/smu.h>
#include <asm/pmac_pfunc.h>
#include <asm/pmac_low_i2c.h>

#ifdef DEBUG
#define DBG(x...) do {\
        printk(KERN_DEBUG "low_i2c:" x);    \
    } while(0)
#else
#define DBG(x...)
#endif

#ifdef DEBUG_LOW
#define DBG_LOW(x...) do {\
        printk(KERN_DEBUG "low_i2c:" x);    \
    } while(0)
#else
#define DBG_LOW(x...)
#endif


static int pmac_i2c_force_poll = 1;

/*
 * A bus structure. Each bus in the system has such a structure associated.
 */
struct pmac_i2c_bus
{
    struct list_head    link;
    struct device_node  *controller;
    struct device_node  *busnode;
    int         type;
    int         flags;
    struct i2c_adapter  adapter;
    void            *hostdata;
    int         channel;    /* some hosts have multiple */
    int         mode;       /* current mode */
    struct mutex        mutex;
    int         opened;
    int         polled;     /* open mode */
    struct platform_device  *platform_dev;

    /* ops */
    int (*open)(struct pmac_i2c_bus *bus);
    void (*close)(struct pmac_i2c_bus *bus);
    int (*xfer)(struct pmac_i2c_bus *bus, u8 addrdir, int subsize,
            u32 subaddr, u8 *data, int len);
};

static LIST_HEAD(pmac_i2c_busses);

/*
 * Keywest implementation
 */

struct pmac_i2c_host_kw
{
    struct mutex        mutex;      /* Access mutex for use by
                         * i2c-keywest */
    void __iomem        *base;      /* register base address */
    int         bsteps;     /* register stepping */
    int         speed;      /* speed */
    int         irq;
    u8          *data;
    unsigned        len;
    int         state;
    int         rw;
    int         polled;
    int         result;
    struct completion   complete;
    spinlock_t      lock;
    struct timer_list   timeout_timer;
};

/* Register indices */
typedef enum {
    reg_mode = 0,
    reg_control,
    reg_status,
    reg_isr,
    reg_ier,
    reg_addr,
    reg_subaddr,
    reg_data
} reg_t;

/* The Tumbler audio equalizer can be really slow sometimes */
#define KW_POLL_TIMEOUT     (2*HZ)

/* Mode register */
#define KW_I2C_MODE_100KHZ  0x00
#define KW_I2C_MODE_50KHZ   0x01
#define KW_I2C_MODE_25KHZ   0x02
#define KW_I2C_MODE_DUMB    0x00
#define KW_I2C_MODE_STANDARD    0x04
#define KW_I2C_MODE_STANDARDSUB 0x08
#define KW_I2C_MODE_COMBINED    0x0C
#define KW_I2C_MODE_MODE_MASK   0x0C
#define KW_I2C_MODE_CHAN_MASK   0xF0

/* Control register */
#define KW_I2C_CTL_AAK      0x01
#define KW_I2C_CTL_XADDR    0x02
#define KW_I2C_CTL_STOP     0x04
#define KW_I2C_CTL_START    0x08

/* Status register */
#define KW_I2C_STAT_BUSY    0x01
#define KW_I2C_STAT_LAST_AAK    0x02
#define KW_I2C_STAT_LAST_RW 0x04
#define KW_I2C_STAT_SDA     0x08
#define KW_I2C_STAT_SCL     0x10

/* IER & ISR registers */
#define KW_I2C_IRQ_DATA     0x01
#define KW_I2C_IRQ_ADDR     0x02
#define KW_I2C_IRQ_STOP     0x04
#define KW_I2C_IRQ_START    0x08
#define KW_I2C_IRQ_MASK     0x0F

/* State machine states */
enum {
    state_idle,
    state_addr,
    state_read,
    state_write,
    state_stop,
    state_dead
};

#define WRONG_STATE(name) do {\
        printk(KERN_DEBUG "KW: wrong state. Got %s, state: %s " \
               "(isr: %02x)\n", \
               name, __kw_state_names[host->state], isr); \
    } while(0)

static const char *__kw_state_names[] = {
    "state_idle",
    "state_addr",
    "state_read",
    "state_write",
    "state_stop",
    "state_dead"
};

static inline u8 __kw_read_reg(struct pmac_i2c_host_kw *host, reg_t reg)
{
    return readb(host->base + (((unsigned int)reg) << host->bsteps));
}

static inline void __kw_write_reg(struct pmac_i2c_host_kw *host,
                  reg_t reg, u8 val)
{
    writeb(val, host->base + (((unsigned)reg) << host->bsteps));
    (void)__kw_read_reg(host, reg_subaddr);
}

#define kw_write_reg(reg, val)  __kw_write_reg(host, reg, val)
#define kw_read_reg(reg)    __kw_read_reg(host, reg)

static u8 kw_i2c_wait_interrupt(struct pmac_i2c_host_kw *host)
{
    int i, j;
    u8 isr;
    
    for (i = 0; i < 1000; i++) {
        isr = kw_read_reg(reg_isr) & KW_I2C_IRQ_MASK;
        if (isr != 0)
            return isr;

        /* This code is used with the timebase frozen, we cannot rely
         * on udelay nor schedule when in polled mode !
         * For now, just use a bogus loop....
         */
        if (host->polled) {
            for (j = 1; j < 100000; j++)
                mb();
        } else
            msleep(1);
    }
    return isr;
}

static void kw_i2c_do_stop(struct pmac_i2c_host_kw *host, int result)
{
    kw_write_reg(reg_control, KW_I2C_CTL_STOP);
    host->state = state_stop;
    host->result = result;
}


static void kw_i2c_handle_interrupt(struct pmac_i2c_host_kw *host, u8 isr)
{
    u8 ack;

    DBG_LOW("kw_handle_interrupt(%s, isr: %x)\n",
        __kw_state_names[host->state], isr);

    if (host->state == state_idle) {
        printk(KERN_WARNING "low_i2c: Keywest got an out of state"
               " interrupt, ignoring\n");
        kw_write_reg(reg_isr, isr);
        return;
    }

    if (isr == 0) {
        printk(KERN_WARNING "low_i2c: Timeout in i2c transfer"
               " on keywest !\n");
        if (host->state != state_stop) {
            kw_i2c_do_stop(host, -EIO);
            return;
        }
        ack = kw_read_reg(reg_status);
        if (ack & KW_I2C_STAT_BUSY)
            kw_write_reg(reg_status, 0);
        host->state = state_idle;
        kw_write_reg(reg_ier, 0x00);
        if (!host->polled)
            complete(&host->complete);
        return;
    }

    if (isr & KW_I2C_IRQ_ADDR) {
        ack = kw_read_reg(reg_status);
        if (host->state != state_addr) {
            WRONG_STATE("KW_I2C_IRQ_ADDR"); 
            kw_i2c_do_stop(host, -EIO);
        }
        if ((ack & KW_I2C_STAT_LAST_AAK) == 0) {
            host->result = -ENXIO;
            host->state = state_stop;
            DBG_LOW("KW: NAK on address\n");
        } else {
            if (host->len == 0)
                kw_i2c_do_stop(host, 0);
            else if (host->rw) {
                host->state = state_read;
                if (host->len > 1)
                    kw_write_reg(reg_control,
                             KW_I2C_CTL_AAK);
            } else {
                host->state = state_write;
                kw_write_reg(reg_data, *(host->data++));
                host->len--;
            }
        }
        kw_write_reg(reg_isr, KW_I2C_IRQ_ADDR);
    }

    if (isr & KW_I2C_IRQ_DATA) {
        if (host->state == state_read) {
            *(host->data++) = kw_read_reg(reg_data);
            host->len--;
            kw_write_reg(reg_isr, KW_I2C_IRQ_DATA);
            if (host->len == 0)
                host->state = state_stop;
            else if (host->len == 1)
                kw_write_reg(reg_control, 0);
        } else if (host->state == state_write) {
            ack = kw_read_reg(reg_status);
            if ((ack & KW_I2C_STAT_LAST_AAK) == 0) {
                DBG_LOW("KW: nack on data write\n");
                host->result = -EFBIG;
                host->state = state_stop;
            } else if (host->len) {
                kw_write_reg(reg_data, *(host->data++));
                host->len--;
            } else
                kw_i2c_do_stop(host, 0);
        } else {
            WRONG_STATE("KW_I2C_IRQ_DATA"); 
            if (host->state != state_stop)
                kw_i2c_do_stop(host, -EIO);
        }
        kw_write_reg(reg_isr, KW_I2C_IRQ_DATA);
    }

    if (isr & KW_I2C_IRQ_STOP) {
        kw_write_reg(reg_isr, KW_I2C_IRQ_STOP);
        if (host->state != state_stop) {
            WRONG_STATE("KW_I2C_IRQ_STOP");
            host->result = -EIO;
        }
        host->state = state_idle;
        if (!host->polled)
            complete(&host->complete);
    }

    /* Below should only happen in manual mode which we don't use ... */
    if (isr & KW_I2C_IRQ_START)
        kw_write_reg(reg_isr, KW_I2C_IRQ_START);

}

/* Interrupt handler */
static irqreturn_t kw_i2c_irq(int irq, void *dev_id)
{
    struct pmac_i2c_host_kw *host = dev_id;
    unsigned long flags;

    spin_lock_irqsave(&host->lock, flags);
    del_timer(&host->timeout_timer);
    kw_i2c_handle_interrupt(host, kw_read_reg(reg_isr));
    if (host->state != state_idle) {
        host->timeout_timer.expires = jiffies + KW_POLL_TIMEOUT;
        add_timer(&host->timeout_timer);
    }
    spin_unlock_irqrestore(&host->lock, flags);
    return IRQ_HANDLED;
}

static void kw_i2c_timeout(unsigned long data)
{
    struct pmac_i2c_host_kw *host = (struct pmac_i2c_host_kw *)data;
    unsigned long flags;

    spin_lock_irqsave(&host->lock, flags);

    /*
     * If the timer is pending, that means we raced with the
     * irq, in which case we just return
     */
    if (timer_pending(&host->timeout_timer))
        goto skip;

    kw_i2c_handle_interrupt(host, kw_read_reg(reg_isr));
    if (host->state != state_idle) {
        host->timeout_timer.expires = jiffies + KW_POLL_TIMEOUT;
        add_timer(&host->timeout_timer);
    }
 skip:
    spin_unlock_irqrestore(&host->lock, flags);
}

static int kw_i2c_open(struct pmac_i2c_bus *bus)
{
    struct pmac_i2c_host_kw *host = bus->hostdata;
    mutex_lock(&host->mutex);
    return 0;
}

static void kw_i2c_close(struct pmac_i2c_bus *bus)
{
    struct pmac_i2c_host_kw *host = bus->hostdata;
    mutex_unlock(&host->mutex);
}

static int kw_i2c_xfer(struct pmac_i2c_bus *bus, u8 addrdir, int subsize,
               u32 subaddr, u8 *data, int len)
{
    struct pmac_i2c_host_kw *host = bus->hostdata;
    u8 mode_reg = host->speed;
    int use_irq = host->irq != NO_IRQ && !bus->polled;

    /* Setup mode & subaddress if any */
    switch(bus->mode) {
    case pmac_i2c_mode_dumb:
        return -EINVAL;
    case pmac_i2c_mode_std:
        mode_reg |= KW_I2C_MODE_STANDARD;
        if (subsize != 0)
            return -EINVAL;
        break;
    case pmac_i2c_mode_stdsub:
        mode_reg |= KW_I2C_MODE_STANDARDSUB;
        if (subsize != 1)
            return -EINVAL;
        break;
    case pmac_i2c_mode_combined:
        mode_reg |= KW_I2C_MODE_COMBINED;
        if (subsize != 1)
            return -EINVAL;
        break;
    }

    /* Setup channel & clear pending irqs */
    kw_write_reg(reg_isr, kw_read_reg(reg_isr));
    kw_write_reg(reg_mode, mode_reg | (bus->channel << 4));
    kw_write_reg(reg_status, 0);

    /* Set up address and r/w bit, strip possible stale bus number from
     * address top bits
     */
    kw_write_reg(reg_addr, addrdir & 0xff);

    /* Set up the sub address */
    if ((mode_reg & KW_I2C_MODE_MODE_MASK) == KW_I2C_MODE_STANDARDSUB
        || (mode_reg & KW_I2C_MODE_MODE_MASK) == KW_I2C_MODE_COMBINED)
        kw_write_reg(reg_subaddr, subaddr);

    /* Prepare for async operations */
    host->data = data;
    host->len = len;
    host->state = state_addr;
    host->result = 0;
    host->rw = (addrdir & 1);
    host->polled = bus->polled;

    /* Enable interrupt if not using polled mode and interrupt is
     * available
     */
    if (use_irq) {
        /* Clear completion */
        INIT_COMPLETION(host->complete);
        /* Ack stale interrupts */
        kw_write_reg(reg_isr, kw_read_reg(reg_isr));
        /* Arm timeout */
        host->timeout_timer.expires = jiffies + KW_POLL_TIMEOUT;
        add_timer(&host->timeout_timer);
        /* Enable emission */
        kw_write_reg(reg_ier, KW_I2C_IRQ_MASK);
    }

    /* Start sending address */
    kw_write_reg(reg_control, KW_I2C_CTL_XADDR);

    /* Wait for completion */
    if (use_irq)
        wait_for_completion(&host->complete);
    else {
        while(host->state != state_idle) {
            unsigned long flags;

            u8 isr = kw_i2c_wait_interrupt(host);
            spin_lock_irqsave(&host->lock, flags);
            kw_i2c_handle_interrupt(host, isr);
            spin_unlock_irqrestore(&host->lock, flags);
        }
    }

    /* Disable emission */
    kw_write_reg(reg_ier, 0);

    return host->result;
}

static struct pmac_i2c_host_kw *__init kw_i2c_host_init(struct device_node *np)
{
    struct pmac_i2c_host_kw *host;
    const u32       *psteps, *prate, *addrp;
    u32         steps;

    host = kzalloc(sizeof(struct pmac_i2c_host_kw), GFP_KERNEL);
    if (host == NULL) {
        printk(KERN_ERR "low_i2c: Can't allocate host for %s\n",
               np->full_name);
        return NULL;
    }

    /* Apple is kind enough to provide a valid AAPL,address property
     * on all i2c keywest nodes so far ... we would have to fallback
     * to macio parsing if that wasn't the case
     */
    addrp = of_get_property(np, "AAPL,address", NULL);
    if (addrp == NULL) {
        printk(KERN_ERR "low_i2c: Can't find address for %s\n",
               np->full_name);
        kfree(host);
        return NULL;
    }
    mutex_init(&host->mutex);
    init_completion(&host->complete);
    spin_lock_init(&host->lock);
    init_timer(&host->timeout_timer);
    host->timeout_timer.function = kw_i2c_timeout;
    host->timeout_timer.data = (unsigned long)host;

    psteps = of_get_property(np, "AAPL,address-step", NULL);
    steps = psteps ? (*psteps) : 0x10;
    for (host->bsteps = 0; (steps & 0x01) == 0; host->bsteps++)
        steps >>= 1;
    /* Select interface rate */
    host->speed = KW_I2C_MODE_25KHZ;
    prate = of_get_property(np, "AAPL,i2c-rate", NULL);
    if (prate) switch(*prate) {
    case 100:
        host->speed = KW_I2C_MODE_100KHZ;
        break;
    case 50:
        host->speed = KW_I2C_MODE_50KHZ;
        break;
    case 25:
        host->speed = KW_I2C_MODE_25KHZ;
        break;
    }   
    host->irq = irq_of_parse_and_map(np, 0);
    if (host->irq == NO_IRQ)
        printk(KERN_WARNING
               "low_i2c: Failed to map interrupt for %s\n",
               np->full_name);

    host->base = ioremap((*addrp), 0x1000);
    if (host->base == NULL) {
        printk(KERN_ERR "low_i2c: Can't map registers for %s\n",
               np->full_name);
        kfree(host);
        return NULL;
    }

    /* Make sure IRQ is disabled */
    kw_write_reg(reg_ier, 0);

    /* Request chip interrupt. We set IRQF_NO_SUSPEND because we don't
     * want that interrupt disabled between the 2 passes of driver
     * suspend or we'll have issues running the pfuncs
     */
    if (request_irq(host->irq, kw_i2c_irq, IRQF_NO_SUSPEND,
            "keywest i2c", host))
        host->irq = NO_IRQ;

    printk(KERN_INFO "KeyWest i2c @0x%08x irq %d %s\n",
           *addrp, host->irq, np->full_name);

    return host;
}


static void __init kw_i2c_add(struct pmac_i2c_host_kw *host,
                  struct device_node *controller,
                  struct device_node *busnode,
                  int channel)
{
    struct pmac_i2c_bus *bus;

    bus = kzalloc(sizeof(struct pmac_i2c_bus), GFP_KERNEL);
    if (bus == NULL)
        return;

    bus->controller = of_node_get(controller);
    bus->busnode = of_node_get(busnode);
    bus->type = pmac_i2c_bus_keywest;
    bus->hostdata = host;
    bus->channel = channel;
    bus->mode = pmac_i2c_mode_std;
    bus->open = kw_i2c_open;
    bus->close = kw_i2c_close;
    bus->xfer = kw_i2c_xfer;
    mutex_init(&bus->mutex);
    if (controller == busnode)
        bus->flags = pmac_i2c_multibus;
    list_add(&bus->link, &pmac_i2c_busses);

    printk(KERN_INFO " channel %d bus %s\n", channel,
           (controller == busnode) ? "<multibus>" : busnode->full_name);
}

static void __init kw_i2c_probe(void)
{
    struct device_node *np, *child, *parent;

    /* Probe keywest-i2c busses */
    for_each_compatible_node(np, "i2c","keywest-i2c") {
        struct pmac_i2c_host_kw *host;
        int multibus;

        /* Found one, init a host structure */
        host = kw_i2c_host_init(np);
        if (host == NULL)
            continue;

        /* Now check if we have a multibus setup (old style) or if we
         * have proper bus nodes. Note that the "new" way (proper bus
         * nodes) might cause us to not create some busses that are
         * kept hidden in the device-tree. In the future, we might
         * want to work around that by creating busses without a node
         * but not for now
         */
        child = of_get_next_child(np, NULL);
        multibus = !child || strcmp(child->name, "i2c-bus");
        of_node_put(child);

        /* For a multibus setup, we get the bus count based on the
         * parent type
         */
        if (multibus) {
            int chans, i;

            parent = of_get_parent(np);
            if (parent == NULL)
                continue;
            chans = parent->name[0] == 'u' ? 2 : 1;
            for (i = 0; i < chans; i++)
                kw_i2c_add(host, np, np, i);
        } else {
            for (child = NULL;
                 (child = of_get_next_child(np, child)) != NULL;) {
                const u32 *reg = of_get_property(child,
                        "reg", NULL);
                if (reg == NULL)
                    continue;
                kw_i2c_add(host, np, child, *reg);
            }
        }
    }
}


/*
 *
 * PMU implementation
 *
 */

#ifdef CONFIG_ADB_PMU

/*
 * i2c command block to the PMU
 */
struct pmu_i2c_hdr {
    u8  bus;
    u8  mode;
    u8  bus2;
    u8  address;
    u8  sub_addr;
    u8  comb_addr;
    u8  count;
    u8  data[];
};

static void pmu_i2c_complete(struct adb_request *req)
{
    complete(req->arg);
}

static int pmu_i2c_xfer(struct pmac_i2c_bus *bus, u8 addrdir, int subsize,
            u32 subaddr, u8 *data, int len)
{
    struct adb_request *req = bus->hostdata;
    struct pmu_i2c_hdr *hdr = (struct pmu_i2c_hdr *)&req->data[1];
    struct completion comp;
    int read = addrdir & 1;
    int retry;
    int rc = 0;

    /* For now, limit ourselves to 16 bytes transfers */
    if (len > 16)
        return -EINVAL;

    init_completion(&comp);

    for (retry = 0; retry < 16; retry++) {
        memset(req, 0, sizeof(struct adb_request));
        hdr->bus = bus->channel;
        hdr->count = len;

        switch(bus->mode) {
        case pmac_i2c_mode_std:
            if (subsize != 0)
                return -EINVAL;
            hdr->address = addrdir;
            hdr->mode = PMU_I2C_MODE_SIMPLE;
            break;
        case pmac_i2c_mode_stdsub:
        case pmac_i2c_mode_combined:
            if (subsize != 1)
                return -EINVAL;
            hdr->address = addrdir & 0xfe;
            hdr->comb_addr = addrdir;
            hdr->sub_addr = subaddr;
            if (bus->mode == pmac_i2c_mode_stdsub)
                hdr->mode = PMU_I2C_MODE_STDSUB;
            else
                hdr->mode = PMU_I2C_MODE_COMBINED;
            break;
        default:
            return -EINVAL;
        }

        INIT_COMPLETION(comp);
        req->data[0] = PMU_I2C_CMD;
        req->reply[0] = 0xff;
        req->nbytes = sizeof(struct pmu_i2c_hdr) + 1;
        req->done = pmu_i2c_complete;
        req->arg = &comp;
        if (!read && len) {
            memcpy(hdr->data, data, len);
            req->nbytes += len;
        }
        rc = pmu_queue_request(req);
        if (rc)
            return rc;
        wait_for_completion(&comp);
        if (req->reply[0] == PMU_I2C_STATUS_OK)
            break;
        msleep(15);
    }
    if (req->reply[0] != PMU_I2C_STATUS_OK)
        return -EIO;

    for (retry = 0; retry < 16; retry++) {
        memset(req, 0, sizeof(struct adb_request));

        /* I know that looks like a lot, slow as hell, but darwin
         * does it so let's be on the safe side for now
         */
        msleep(15);

        hdr->bus = PMU_I2C_BUS_STATUS;

        INIT_COMPLETION(comp);
        req->data[0] = PMU_I2C_CMD;
        req->reply[0] = 0xff;
        req->nbytes = 2;
        req->done = pmu_i2c_complete;
        req->arg = &comp;
        rc = pmu_queue_request(req);
        if (rc)
            return rc;
        wait_for_completion(&comp);

        if (req->reply[0] == PMU_I2C_STATUS_OK && !read)
            return 0;
        if (req->reply[0] == PMU_I2C_STATUS_DATAREAD && read) {
            int rlen = req->reply_len - 1;

            if (rlen != len) {
                printk(KERN_WARNING "low_i2c: PMU returned %d"
                       " bytes, expected %d !\n", rlen, len);
                return -EIO;
            }
            if (len)
                memcpy(data, &req->reply[1], len);
            return 0;
        }
    }
    return -EIO;
}

static void __init pmu_i2c_probe(void)
{
    struct pmac_i2c_bus *bus;
    struct device_node *busnode;
    int channel, sz;

    if (!pmu_present())
        return;

    /* There might or might not be a "pmu-i2c" node, we use that
     * or via-pmu itself, whatever we find. I haven't seen a machine
     * with separate bus nodes, so we assume a multibus setup
     */
    busnode = of_find_node_by_name(NULL, "pmu-i2c");
    if (busnode == NULL)
        busnode = of_find_node_by_name(NULL, "via-pmu");
    if (busnode == NULL)
        return;

    printk(KERN_INFO "PMU i2c %s\n", busnode->full_name);

    /*
     * We add bus 1 and 2 only for now, bus 0 is "special"
     */
    for (channel = 1; channel <= 2; channel++) {
        sz = sizeof(struct pmac_i2c_bus) + sizeof(struct adb_request);
        bus = kzalloc(sz, GFP_KERNEL);
        if (bus == NULL)
            return;

        bus->controller = busnode;
        bus->busnode = busnode;
        bus->type = pmac_i2c_bus_pmu;
        bus->channel = channel;
        bus->mode = pmac_i2c_mode_std;
        bus->hostdata = bus + 1;
        bus->xfer = pmu_i2c_xfer;
        mutex_init(&bus->mutex);
        bus->flags = pmac_i2c_multibus;
        list_add(&bus->link, &pmac_i2c_busses);

        printk(KERN_INFO " channel %d bus <multibus>\n", channel);
    }
}

#endif /* CONFIG_ADB_PMU */


/*
 *
 * SMU implementation
 *
 */

#ifdef CONFIG_PMAC_SMU

static void smu_i2c_complete(struct smu_i2c_cmd *cmd, void *misc)
{
    complete(misc);
}

static int smu_i2c_xfer(struct pmac_i2c_bus *bus, u8 addrdir, int subsize,
            u32 subaddr, u8 *data, int len)
{
    struct smu_i2c_cmd *cmd = bus->hostdata;
    struct completion comp;
    int read = addrdir & 1;
    int rc = 0;

    if ((read && len > SMU_I2C_READ_MAX) ||
        ((!read) && len > SMU_I2C_WRITE_MAX))
        return -EINVAL;

    memset(cmd, 0, sizeof(struct smu_i2c_cmd));
    cmd->info.bus = bus->channel;
    cmd->info.devaddr = addrdir;
    cmd->info.datalen = len;

    switch(bus->mode) {
    case pmac_i2c_mode_std:
        if (subsize != 0)
            return -EINVAL;
        cmd->info.type = SMU_I2C_TRANSFER_SIMPLE;
        break;
    case pmac_i2c_mode_stdsub:
    case pmac_i2c_mode_combined:
        if (subsize > 3 || subsize < 1)
            return -EINVAL;
        cmd->info.sublen = subsize;
        /* that's big-endian only but heh ! */
        memcpy(&cmd->info.subaddr, ((char *)&subaddr) + (4 - subsize),
               subsize);
        if (bus->mode == pmac_i2c_mode_stdsub)
            cmd->info.type = SMU_I2C_TRANSFER_STDSUB;
        else
            cmd->info.type = SMU_I2C_TRANSFER_COMBINED;
        break;
    default:
        return -EINVAL;
    }
    if (!read && len)
        memcpy(cmd->info.data, data, len);

    init_completion(&comp);
    cmd->done = smu_i2c_complete;
    cmd->misc = &comp;
    rc = smu_queue_i2c(cmd);
    if (rc < 0)
        return rc;
    wait_for_completion(&comp);
    rc = cmd->status;

    if (read && len)
        memcpy(data, cmd->info.data, len);
    return rc < 0 ? rc : 0;
}

static void __init smu_i2c_probe(void)
{
    struct device_node *controller, *busnode;
    struct pmac_i2c_bus *bus;
    const u32 *reg;
    int sz;

    if (!smu_present())
        return;

    controller = of_find_node_by_name(NULL, "smu-i2c-control");
    if (controller == NULL)
        controller = of_find_node_by_name(NULL, "smu");
    if (controller == NULL)
        return;

    printk(KERN_INFO "SMU i2c %s\n", controller->full_name);

    /* Look for childs, note that they might not be of the right
     * type as older device trees mix i2c busses and other things
     * at the same level
     */
    for (busnode = NULL;
         (busnode = of_get_next_child(controller, busnode)) != NULL;) {
        if (strcmp(busnode->type, "i2c") &&
            strcmp(busnode->type, "i2c-bus"))
            continue;
        reg = of_get_property(busnode, "reg", NULL);
        if (reg == NULL)
            continue;

        sz = sizeof(struct pmac_i2c_bus) + sizeof(struct smu_i2c_cmd);
        bus = kzalloc(sz, GFP_KERNEL);
        if (bus == NULL)
            return;

        bus->controller = controller;
        bus->busnode = of_node_get(busnode);
        bus->type = pmac_i2c_bus_smu;
        bus->channel = *reg;
        bus->mode = pmac_i2c_mode_std;
        bus->hostdata = bus + 1;
        bus->xfer = smu_i2c_xfer;
        mutex_init(&bus->mutex);
        bus->flags = 0;
        list_add(&bus->link, &pmac_i2c_busses);

        printk(KERN_INFO " channel %x bus %s\n",
               bus->channel, busnode->full_name);
    }
}

#endif /* CONFIG_PMAC_SMU */

/*
 *
 * Core code
 *
 */


struct pmac_i2c_bus *pmac_i2c_find_bus(struct device_node *node)
{
    struct device_node *p = of_node_get(node);
    struct device_node *prev = NULL;
    struct pmac_i2c_bus *bus;

    while(p) {
        list_for_each_entry(bus, &pmac_i2c_busses, link) {
            if (p == bus->busnode) {
                if (prev && bus->flags & pmac_i2c_multibus) {
                    const u32 *reg;
                    reg = of_get_property(prev, "reg",
                                NULL);
                    if (!reg)
                        continue;
                    if (((*reg) >> 8) != bus->channel)
                        continue;
                }
                of_node_put(p);
                of_node_put(prev);
                return bus;
            }
        }
        of_node_put(prev);
        prev = p;
        p = of_get_parent(p);
    }
    return NULL;
}
EXPORT_SYMBOL_GPL(pmac_i2c_find_bus);

u8 pmac_i2c_get_dev_addr(struct device_node *device)
{
    const u32 *reg = of_get_property(device, "reg", NULL);

    if (reg == NULL)
        return 0;

    return (*reg) & 0xff;
}
EXPORT_SYMBOL_GPL(pmac_i2c_get_dev_addr);

struct device_node *pmac_i2c_get_controller(struct pmac_i2c_bus *bus)
{
    return bus->controller;
}
EXPORT_SYMBOL_GPL(pmac_i2c_get_controller);

struct device_node *pmac_i2c_get_bus_node(struct pmac_i2c_bus *bus)
{
    return bus->busnode;
}
EXPORT_SYMBOL_GPL(pmac_i2c_get_bus_node);

int pmac_i2c_get_type(struct pmac_i2c_bus *bus)
{
    return bus->type;
}
EXPORT_SYMBOL_GPL(pmac_i2c_get_type);

int pmac_i2c_get_flags(struct pmac_i2c_bus *bus)
{
    return bus->flags;
}
EXPORT_SYMBOL_GPL(pmac_i2c_get_flags);

int pmac_i2c_get_channel(struct pmac_i2c_bus *bus)
{
    return bus->channel;
}
EXPORT_SYMBOL_GPL(pmac_i2c_get_channel);


struct i2c_adapter *pmac_i2c_get_adapter(struct pmac_i2c_bus *bus)
{
    return &bus->adapter;
}
EXPORT_SYMBOL_GPL(pmac_i2c_get_adapter);

struct pmac_i2c_bus *pmac_i2c_adapter_to_bus(struct i2c_adapter *adapter)
{
    struct pmac_i2c_bus *bus;

    list_for_each_entry(bus, &pmac_i2c_busses, link)
        if (&bus->adapter == adapter)
            return bus;
    return NULL;
}
EXPORT_SYMBOL_GPL(pmac_i2c_adapter_to_bus);

int pmac_i2c_match_adapter(struct device_node *dev, struct i2c_adapter *adapter)
{
    struct pmac_i2c_bus *bus = pmac_i2c_find_bus(dev);

    if (bus == NULL)
        return 0;
    return (&bus->adapter == adapter);
}
EXPORT_SYMBOL_GPL(pmac_i2c_match_adapter);

int pmac_low_i2c_lock(struct device_node *np)
{
    struct pmac_i2c_bus *bus, *found = NULL;

    list_for_each_entry(bus, &pmac_i2c_busses, link) {
        if (np == bus->controller) {
            found = bus;
            break;
        }
    }
    if (!found)
        return -ENODEV;
    return pmac_i2c_open(bus, 0);
}
EXPORT_SYMBOL_GPL(pmac_low_i2c_lock);

int pmac_low_i2c_unlock(struct device_node *np)
{
    struct pmac_i2c_bus *bus, *found = NULL;

    list_for_each_entry(bus, &pmac_i2c_busses, link) {
        if (np == bus->controller) {
            found = bus;
            break;
        }
    }
    if (!found)
        return -ENODEV;
    pmac_i2c_close(bus);
    return 0;
}
EXPORT_SYMBOL_GPL(pmac_low_i2c_unlock);


int pmac_i2c_open(struct pmac_i2c_bus *bus, int polled)
{
    int rc;

    mutex_lock(&bus->mutex);
    bus->polled = polled || pmac_i2c_force_poll;
    bus->opened = 1;
    bus->mode = pmac_i2c_mode_std;
    if (bus->open && (rc = bus->open(bus)) != 0) {
        bus->opened = 0;
        mutex_unlock(&bus->mutex);
        return rc;
    }
    return 0;
}
EXPORT_SYMBOL_GPL(pmac_i2c_open);

void pmac_i2c_close(struct pmac_i2c_bus *bus)
{
    WARN_ON(!bus->opened);
    if (bus->close)
        bus->close(bus);
    bus->opened = 0;
    mutex_unlock(&bus->mutex);
}
EXPORT_SYMBOL_GPL(pmac_i2c_close);

int pmac_i2c_setmode(struct pmac_i2c_bus *bus, int mode)
{
    WARN_ON(!bus->opened);

    /* Report me if you see the error below as there might be a new
     * "combined4" mode that I need to implement for the SMU bus
     */
    if (mode < pmac_i2c_mode_dumb || mode > pmac_i2c_mode_combined) {
        printk(KERN_ERR "low_i2c: Invalid mode %d requested on"
               " bus %s !\n", mode, bus->busnode->full_name);
        return -EINVAL;
    }
    bus->mode = mode;

    return 0;
}
EXPORT_SYMBOL_GPL(pmac_i2c_setmode);

int pmac_i2c_xfer(struct pmac_i2c_bus *bus, u8 addrdir, int subsize,
          u32 subaddr, u8 *data, int len)
{
    int rc;

    WARN_ON(!bus->opened);

    DBG("xfer() chan=%d, addrdir=0x%x, mode=%d, subsize=%d, subaddr=0x%x,"
        " %d bytes, bus %s\n", bus->channel, addrdir, bus->mode, subsize,
        subaddr, len, bus->busnode->full_name);

    rc = bus->xfer(bus, addrdir, subsize, subaddr, data, len);

#ifdef DEBUG
    if (rc)
        DBG("xfer error %d\n", rc);
#endif
    return rc;
}
EXPORT_SYMBOL_GPL(pmac_i2c_xfer);

/* some quirks for platform function decoding */
enum {
    pmac_i2c_quirk_invmask = 0x00000001u,
    pmac_i2c_quirk_skip = 0x00000002u,
};

static void pmac_i2c_devscan(void (*callback)(struct device_node *dev,
                          int quirks))
{
    struct pmac_i2c_bus *bus;
    struct device_node *np;
    static struct whitelist_ent {
        char *name;
        char *compatible;
        int quirks;
    } whitelist[] = {
        /* XXX Study device-tree's & apple drivers are get the quirks
         * right !
         */
        /* Workaround: It seems that running the clockspreading
         * properties on the eMac will cause lockups during boot.
         * The machine seems to work fine without that. So for now,
         * let's make sure i2c-hwclock doesn't match about "imic"
         * clocks and we'll figure out if we really need to do
         * something special about those later.
         */
        { "i2c-hwclock", "imic5002", pmac_i2c_quirk_skip },
        { "i2c-hwclock", "imic5003", pmac_i2c_quirk_skip },
        { "i2c-hwclock", NULL, pmac_i2c_quirk_invmask },
        { "i2c-cpu-voltage", NULL, 0},
        {  "temp-monitor", NULL, 0 },
        {  "supply-monitor", NULL, 0 },
        { NULL, NULL, 0 },
    };

    /* Only some devices need to have platform functions instanciated
     * here. For now, we have a table. Others, like 9554 i2c GPIOs used
     * on Xserve, if we ever do a driver for them, will use their own
     * platform function instance
     */
    list_for_each_entry(bus, &pmac_i2c_busses, link) {
        for (np = NULL;
             (np = of_get_next_child(bus->busnode, np)) != NULL;) {
            struct whitelist_ent *p;
            /* If multibus, check if device is on that bus */
            if (bus->flags & pmac_i2c_multibus)
                if (bus != pmac_i2c_find_bus(np))
                    continue;
            for (p = whitelist; p->name != NULL; p++) {
                if (strcmp(np->name, p->name))
                    continue;
                if (p->compatible &&
                    !of_device_is_compatible(np, p->compatible))
                    continue;
                if (p->quirks & pmac_i2c_quirk_skip)
                    break;
                callback(np, p->quirks);
                break;
            }
        }
    }
}

#define MAX_I2C_DATA    64

struct pmac_i2c_pf_inst
{
    struct pmac_i2c_bus *bus;
    u8          addr;
    u8          buffer[MAX_I2C_DATA];
    u8          scratch[MAX_I2C_DATA];
    int         bytes;
    int         quirks;
};

static void* pmac_i2c_do_begin(struct pmf_function *func, struct pmf_args *args)
{
    struct pmac_i2c_pf_inst *inst;
    struct pmac_i2c_bus *bus;

    bus = pmac_i2c_find_bus(func->node);
    if (bus == NULL) {
        printk(KERN_ERR "low_i2c: Can't find bus for %s (pfunc)\n",
               func->node->full_name);
        return NULL;
    }
    if (pmac_i2c_open(bus, 0)) {
        printk(KERN_ERR "low_i2c: Can't open i2c bus for %s (pfunc)\n",
               func->node->full_name);
        return NULL;
    }

    /* XXX might need GFP_ATOMIC when called during the suspend process,
     * but then, there are already lots of issues with suspending when
     * near OOM that need to be resolved, the allocator itself should
     * probably make GFP_NOIO implicit during suspend
     */
    inst = kzalloc(sizeof(struct pmac_i2c_pf_inst), GFP_KERNEL);
    if (inst == NULL) {
        pmac_i2c_close(bus);
        return NULL;
    }
    inst->bus = bus;
    inst->addr = pmac_i2c_get_dev_addr(func->node);
    inst->quirks = (int)(long)func->driver_data;
    return inst;
}

static void pmac_i2c_do_end(struct pmf_function *func, void *instdata)
{
    struct pmac_i2c_pf_inst *inst = instdata;

    if (inst == NULL)
        return;
    pmac_i2c_close(inst->bus);
    kfree(inst);
}

static int pmac_i2c_do_read(PMF_STD_ARGS, u32 len)
{
    struct pmac_i2c_pf_inst *inst = instdata;

    inst->bytes = len;
    return pmac_i2c_xfer(inst->bus, inst->addr | pmac_i2c_read, 0, 0,
                 inst->buffer, len);
}

static int pmac_i2c_do_write(PMF_STD_ARGS, u32 len, const u8 *data)
{
    struct pmac_i2c_pf_inst *inst = instdata;

    return pmac_i2c_xfer(inst->bus, inst->addr | pmac_i2c_write, 0, 0,
                 (u8 *)data, len);
}

/* This function is used to do the masking & OR'ing for the "rmw" type
 * callbacks. Ze should apply the mask and OR in the values in the
 * buffer before writing back. The problem is that it seems that
 * various darwin drivers implement the mask/or differently, thus
 * we need to check the quirks first
 */
static void pmac_i2c_do_apply_rmw(struct pmac_i2c_pf_inst *inst,
                  u32 len, const u8 *mask, const u8 *val)
{
    int i;

    if (inst->quirks & pmac_i2c_quirk_invmask) {
        for (i = 0; i < len; i ++)
            inst->scratch[i] = (inst->buffer[i] & mask[i]) | val[i];
    } else {
        for (i = 0; i < len; i ++)
            inst->scratch[i] = (inst->buffer[i] & ~mask[i])
                | (val[i] & mask[i]);
    }
}

static int pmac_i2c_do_rmw(PMF_STD_ARGS, u32 masklen, u32 valuelen,
               u32 totallen, const u8 *maskdata,
               const u8 *valuedata)
{
    struct pmac_i2c_pf_inst *inst = instdata;

    if (masklen > inst->bytes || valuelen > inst->bytes ||
        totallen > inst->bytes || valuelen > masklen)
        return -EINVAL;

    pmac_i2c_do_apply_rmw(inst, masklen, maskdata, valuedata);

    return pmac_i2c_xfer(inst->bus, inst->addr | pmac_i2c_write, 0, 0,
                 inst->scratch, totallen);
}

static int pmac_i2c_do_read_sub(PMF_STD_ARGS, u8 subaddr, u32 len)
{
    struct pmac_i2c_pf_inst *inst = instdata;

    inst->bytes = len;
    return pmac_i2c_xfer(inst->bus, inst->addr | pmac_i2c_read, 1, subaddr,
                 inst->buffer, len);
}

static int pmac_i2c_do_write_sub(PMF_STD_ARGS, u8 subaddr, u32 len,
                     const u8 *data)
{
    struct pmac_i2c_pf_inst *inst = instdata;

    return pmac_i2c_xfer(inst->bus, inst->addr | pmac_i2c_write, 1,
                 subaddr, (u8 *)data, len);
}

static int pmac_i2c_do_set_mode(PMF_STD_ARGS, int mode)
{
    struct pmac_i2c_pf_inst *inst = instdata;

    return pmac_i2c_setmode(inst->bus, mode);
}

static int pmac_i2c_do_rmw_sub(PMF_STD_ARGS, u8 subaddr, u32 masklen,
                   u32 valuelen, u32 totallen, const u8 *maskdata,
                   const u8 *valuedata)
{
    struct pmac_i2c_pf_inst *inst = instdata;

    if (masklen > inst->bytes || valuelen > inst->bytes ||
        totallen > inst->bytes || valuelen > masklen)
        return -EINVAL;

    pmac_i2c_do_apply_rmw(inst, masklen, maskdata, valuedata);

    return pmac_i2c_xfer(inst->bus, inst->addr | pmac_i2c_write, 1,
                 subaddr, inst->scratch, totallen);
}

static int pmac_i2c_do_mask_and_comp(PMF_STD_ARGS, u32 len,
                     const u8 *maskdata,
                     const u8 *valuedata)
{
    struct pmac_i2c_pf_inst *inst = instdata;
    int i, match;

    /* Get return value pointer, it's assumed to be a u32 */
    if (!args || !args->count || !args->u[0].p)
        return -EINVAL;

    /* Check buffer */
    if (len > inst->bytes)
        return -EINVAL;

    for (i = 0, match = 1; match && i < len; i ++)
        if ((inst->buffer[i] & maskdata[i]) != valuedata[i])
            match = 0;
    *args->u[0].p = match;
    return 0;
}

static int pmac_i2c_do_delay(PMF_STD_ARGS, u32 duration)
{
    msleep((duration + 999) / 1000);
    return 0;
}


static struct pmf_handlers pmac_i2c_pfunc_handlers = {
    .begin          = pmac_i2c_do_begin,
    .end            = pmac_i2c_do_end,
    .read_i2c       = pmac_i2c_do_read,
    .write_i2c      = pmac_i2c_do_write,
    .rmw_i2c        = pmac_i2c_do_rmw,
    .read_i2c_sub       = pmac_i2c_do_read_sub,
    .write_i2c_sub      = pmac_i2c_do_write_sub,
    .rmw_i2c_sub        = pmac_i2c_do_rmw_sub,
    .set_i2c_mode       = pmac_i2c_do_set_mode,
    .mask_and_compare   = pmac_i2c_do_mask_and_comp,
    .delay          = pmac_i2c_do_delay,
};

static void __init pmac_i2c_dev_create(struct device_node *np, int quirks)
{
    DBG("dev_create(%s)\n", np->full_name);

    pmf_register_driver(np, &pmac_i2c_pfunc_handlers,
                (void *)(long)quirks);
}

static void __init pmac_i2c_dev_init(struct device_node *np, int quirks)
{
    DBG("dev_create(%s)\n", np->full_name);

    pmf_do_functions(np, NULL, 0, PMF_FLAGS_ON_INIT, NULL);
}

static void pmac_i2c_dev_suspend(struct device_node *np, int quirks)
{
    DBG("dev_suspend(%s)\n", np->full_name);
    pmf_do_functions(np, NULL, 0, PMF_FLAGS_ON_SLEEP, NULL);
}

static void pmac_i2c_dev_resume(struct device_node *np, int quirks)
{
    DBG("dev_resume(%s)\n", np->full_name);
    pmf_do_functions(np, NULL, 0, PMF_FLAGS_ON_WAKE, NULL);
}

void pmac_pfunc_i2c_suspend(void)
{
    pmac_i2c_devscan(pmac_i2c_dev_suspend);
}

void pmac_pfunc_i2c_resume(void)
{
    pmac_i2c_devscan(pmac_i2c_dev_resume);
}

/*
 * Initialize us: probe all i2c busses on the machine, instantiate
 * busses and platform functions as needed.
 */
/* This is non-static as it might be called early by smp code */
int __init pmac_i2c_init(void)
{
    static int i2c_inited;

    if (i2c_inited)
        return 0;
    i2c_inited = 1;

    /* Probe keywest-i2c busses */
    kw_i2c_probe();

#ifdef CONFIG_ADB_PMU
    /* Probe PMU i2c busses */
    pmu_i2c_probe();
#endif

#ifdef CONFIG_PMAC_SMU
    /* Probe SMU i2c busses */
    smu_i2c_probe();
#endif

    /* Now add plaform functions for some known devices */
    pmac_i2c_devscan(pmac_i2c_dev_create);

    return 0;
}
machine_arch_initcall(powermac, pmac_i2c_init);

/* Since pmac_i2c_init can be called too early for the platform device
 * registration, we need to do it at a later time. In our case, subsys
 * happens to fit well, though I agree it's a bit of a hack...
 */
static int __init pmac_i2c_create_platform_devices(void)
{
    struct pmac_i2c_bus *bus;
    int i = 0;

    /* In the case where we are initialized from smp_init(), we must
     * not use the timer (and thus the irq). It's safe from now on
     * though
     */
    pmac_i2c_force_poll = 0;

    /* Create platform devices */
    list_for_each_entry(bus, &pmac_i2c_busses, link) {
        bus->platform_dev =
            platform_device_alloc("i2c-powermac", i++);
        if (bus->platform_dev == NULL)
            return -ENOMEM;
        bus->platform_dev->dev.platform_data = bus;
        bus->platform_dev->dev.of_node = bus->busnode;
        platform_device_add(bus->platform_dev);
    }

    /* Now call platform "init" functions */
    pmac_i2c_devscan(pmac_i2c_dev_init);

    return 0;
}
machine_subsys_initcall(powermac, pmac_i2c_create_platform_devices);