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windfarm_max6690_sensor.c

/*
 * Windfarm PowerMac thermal control.  MAX6690 sensor.
 *
 * Copyright (C) 2005 Paul Mackerras, IBM Corp. <paulus@samba.org>
 *
 * Use and redistribute under the terms of the GNU GPL v2.
 */
#include <linux/types.h>
#include <linux/errno.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/i2c.h>
#include <asm/prom.h>
#include <asm/pmac_low_i2c.h>

#include "windfarm.h"

#define VERSION "0.2"

/* This currently only exports the external temperature sensor,
   since that's all the control loops need. */

/* Some MAX6690 register numbers */
#define MAX6690_INTERNAL_TEMP 0
#define MAX6690_EXTERNAL_TEMP 1

struct wf_6690_sensor {
      struct i2c_client i2c;
      struct wf_sensor  sens;
};

#define wf_to_6690(x)   container_of((x), struct wf_6690_sensor, sens)
#define i2c_to_6690(x)  container_of((x), struct wf_6690_sensor, i2c)

static int wf_max6690_attach(struct i2c_adapter *adapter);
static int wf_max6690_detach(struct i2c_client *client);

static struct i2c_driver wf_max6690_driver = {
      .driver = {
            .name       = "wf_max6690",
      },
      .attach_adapter   = wf_max6690_attach,
      .detach_client    = wf_max6690_detach,
};

static int wf_max6690_get(struct wf_sensor *sr, s32 *value)
{
      struct wf_6690_sensor *max = wf_to_6690(sr);
      s32 data;

      if (max->i2c.adapter == NULL)
            return -ENODEV;

      /* chip gets initialized by firmware */
      data = i2c_smbus_read_byte_data(&max->i2c, MAX6690_EXTERNAL_TEMP);
      if (data < 0)
            return data;
      *value = data << 16;
      return 0;
}

static void wf_max6690_release(struct wf_sensor *sr)
{
      struct wf_6690_sensor *max = wf_to_6690(sr);

      if (max->i2c.adapter) {
            i2c_detach_client(&max->i2c);
            max->i2c.adapter = NULL;
      }
      kfree(max);
}

static struct wf_sensor_ops wf_max6690_ops = {
      .get_value  = wf_max6690_get,
      .release    = wf_max6690_release,
      .owner            = THIS_MODULE,
};

static void wf_max6690_create(struct i2c_adapter *adapter, u8 addr)
{
      struct wf_6690_sensor *max;
      char *name = "backside-temp";

      max = kzalloc(sizeof(struct wf_6690_sensor), GFP_KERNEL);
      if (max == NULL) {
            printk(KERN_ERR "windfarm: Couldn't create MAX6690 sensor %s: "
                   "no memory\n", name);
            return;
      }

      max->sens.ops = &wf_max6690_ops;
      max->sens.name = name;
      max->i2c.addr = addr >> 1;
      max->i2c.adapter = adapter;
      max->i2c.driver = &wf_max6690_driver;
      strncpy(max->i2c.name, name, I2C_NAME_SIZE-1);

      if (i2c_attach_client(&max->i2c)) {
            printk(KERN_ERR "windfarm: failed to attach MAX6690 sensor\n");
            goto fail;
      }

      if (wf_register_sensor(&max->sens)) {
            i2c_detach_client(&max->i2c);
            goto fail;
      }

      return;

 fail:
      kfree(max);
}

static int wf_max6690_attach(struct i2c_adapter *adapter)
{
      struct device_node *busnode, *dev = NULL;
      struct pmac_i2c_bus *bus;
      const char *loc;

      bus = pmac_i2c_adapter_to_bus(adapter);
      if (bus == NULL)
            return -ENODEV;
      busnode = pmac_i2c_get_bus_node(bus);

      while ((dev = of_get_next_child(busnode, dev)) != NULL) {
            u8 addr;

            /* We must re-match the adapter in order to properly check
             * the channel on multibus setups
             */
            if (!pmac_i2c_match_adapter(dev, adapter))
                  continue;
            if (!of_device_is_compatible(dev, "max6690"))
                  continue;
            addr = pmac_i2c_get_dev_addr(dev);
            loc = of_get_property(dev, "hwsensor-location", NULL);
            if (loc == NULL || addr == 0)
                  continue;
            printk("found max6690, loc=%s addr=0x%02x\n", loc, addr);
            if (strcmp(loc, "BACKSIDE"))
                  continue;
            wf_max6690_create(adapter, addr);
      }

      return 0;
}

static int wf_max6690_detach(struct i2c_client *client)
{
      struct wf_6690_sensor *max = i2c_to_6690(client);

      max->i2c.adapter = NULL;
      wf_unregister_sensor(&max->sens);

      return 0;
}

static int __init wf_max6690_sensor_init(void)
{
      /* Don't register on old machines that use therm_pm72 for now */
      if (machine_is_compatible("PowerMac7,2") ||
          machine_is_compatible("PowerMac7,3") ||
          machine_is_compatible("RackMac3,1"))
            return -ENODEV;
      return i2c_add_driver(&wf_max6690_driver);
}

static void __exit wf_max6690_sensor_exit(void)
{
      i2c_del_driver(&wf_max6690_driver);
}

module_init(wf_max6690_sensor_init);
module_exit(wf_max6690_sensor_exit);

MODULE_AUTHOR("Paul Mackerras <paulus@samba.org>");
MODULE_DESCRIPTION("MAX6690 sensor objects for PowerMac thermal control");
MODULE_LICENSE("GPL");

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