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low_i2c.c

/*
 * arch/powerpc/platforms/powermac/low_i2c.c
 *
 *  Copyright (C) 2003-2005 Ben. Herrenschmidt (benh@kernel.crashing.org)
 *
 *  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/module.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 <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);
      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);
}

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 */
      if (request_irq(host->irq, kw_i2c_irq, 0, "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, chans, i;

            /* 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) {
                  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 thigns
       * 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);


void pmac_i2c_attach_adapter(struct pmac_i2c_bus *bus,
                       struct i2c_adapter *adapter)
{
      WARN_ON(bus->adapter != NULL);
      bus->adapter = adapter;
}
EXPORT_SYMBOL_GPL(pmac_i2c_attach_adapter);

void pmac_i2c_detach_adapter(struct pmac_i2c_bus *bus,
                       struct i2c_adapter *adapter)
{
      WARN_ON(bus->adapter != adapter);
      bus->adapter = NULL;
}
EXPORT_SYMBOL_GPL(pmac_i2c_detach_adapter);

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);
      if (inst)
            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;
            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);

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