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windfarm_lm75_sensor.c

/*
 * Windfarm PowerMac thermal control. LM75 sensor
 *
 * (c) Copyright 2005 Benjamin Herrenschmidt, IBM Corp.
 *                    <benh@kernel.crashing.org>
 *
 * Released under the term of the GNU GPL v2.
 */

#include <linux/types.h>
#include <linux/errno.h>
#include <linux/kernel.h>
#include <linux/delay.h>
#include <linux/slab.h>
#include <linux/init.h>
#include <linux/wait.h>
#include <linux/i2c.h>
#include <asm/prom.h>
#include <asm/machdep.h>
#include <asm/io.h>
#include <asm/system.h>
#include <asm/sections.h>
#include <asm/pmac_low_i2c.h>

#include "windfarm.h"

#define VERSION "0.2"

#undef DEBUG

#ifdef DEBUG
#define DBG(args...)    printk(args)
#else
#define DBG(args...)    do { } while(0)
#endif

struct wf_lm75_sensor {
      int               ds1775 : 1;
      int               inited : 1;
      struct      i2c_client  i2c;
      struct      wf_sensor   sens;
};
#define wf_to_lm75(c) container_of(c, struct wf_lm75_sensor, sens)
#define i2c_to_lm75(c) container_of(c, struct wf_lm75_sensor, i2c)

static int wf_lm75_attach(struct i2c_adapter *adapter);
static int wf_lm75_detach(struct i2c_client *client);

static struct i2c_driver wf_lm75_driver = {
      .driver = {
            .name = "wf_lm75",
      },
      .attach_adapter   = wf_lm75_attach,
      .detach_client    = wf_lm75_detach,
};

static int wf_lm75_get(struct wf_sensor *sr, s32 *value)
{
      struct wf_lm75_sensor *lm = wf_to_lm75(sr);
      s32 data;

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

      /* Init chip if necessary */
      if (!lm->inited) {
            u8 cfg_new, cfg = (u8)i2c_smbus_read_byte_data(&lm->i2c, 1);

            DBG("wf_lm75: Initializing %s, cfg was: %02x\n",
                sr->name, cfg);

            /* clear shutdown bit, keep other settings as left by
             * the firmware for now
             */
            cfg_new = cfg & ~0x01;
            i2c_smbus_write_byte_data(&lm->i2c, 1, cfg_new);
            lm->inited = 1;

            /* If we just powered it up, let's wait 200 ms */
            msleep(200);
      }

      /* Read temperature register */
      data = (s32)le16_to_cpu(i2c_smbus_read_word_data(&lm->i2c, 0));
      data <<= 8;
      *value = data;

      return 0;
}

static void wf_lm75_release(struct wf_sensor *sr)
{
      struct wf_lm75_sensor *lm = wf_to_lm75(sr);

      /* check if client is registered and detach from i2c */
      if (lm->i2c.adapter) {
            i2c_detach_client(&lm->i2c);
            lm->i2c.adapter = NULL;
      }

      kfree(lm);
}

static struct wf_sensor_ops wf_lm75_ops = {
      .get_value  = wf_lm75_get,
      .release    = wf_lm75_release,
      .owner            = THIS_MODULE,
};

static struct wf_lm75_sensor *wf_lm75_create(struct i2c_adapter *adapter,
                                   u8 addr, int ds1775,
                                   const char *loc)
{
      struct wf_lm75_sensor *lm;
      int rc;

      DBG("wf_lm75: creating  %s device at address 0x%02x\n",
          ds1775 ? "ds1775" : "lm75", addr);

      lm = kzalloc(sizeof(struct wf_lm75_sensor), GFP_KERNEL);
      if (lm == NULL)
            return NULL;

      /* Usual rant about sensor names not beeing very consistent in
       * the device-tree, oh well ...
       * Add more entries below as you deal with more setups
       */
      if (!strcmp(loc, "Hard drive") || !strcmp(loc, "DRIVE BAY"))
            lm->sens.name = "hd-temp";
      else
            goto fail;

      lm->inited = 0;
      lm->sens.ops = &wf_lm75_ops;
      lm->ds1775 = ds1775;
      lm->i2c.addr = (addr >> 1) & 0x7f;
      lm->i2c.adapter = adapter;
      lm->i2c.driver = &wf_lm75_driver;
      strncpy(lm->i2c.name, lm->sens.name, I2C_NAME_SIZE-1);

      rc = i2c_attach_client(&lm->i2c);
      if (rc) {
            printk(KERN_ERR "windfarm: failed to attach %s %s to i2c,"
                   " err %d\n", ds1775 ? "ds1775" : "lm75",
                   lm->i2c.name, rc);
            goto fail;
      }

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

      return lm;
 fail:
      kfree(lm);
      return NULL;
}

static int wf_lm75_attach(struct i2c_adapter *adapter)
{
      struct device_node *busnode, *dev;
      struct pmac_i2c_bus *bus;

      DBG("wf_lm75: adapter %s detected\n", adapter->name);

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

      DBG("wf_lm75: bus found, looking for device...\n");

      /* Now look for lm75(s) in there */
      for (dev = NULL;
           (dev = of_get_next_child(busnode, dev)) != NULL;) {
            const char *loc =
                  of_get_property(dev, "hwsensor-location", 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;
            addr = pmac_i2c_get_dev_addr(dev);
            if (loc == NULL || addr == 0)
                  continue;
            /* real lm75 */
            if (of_device_is_compatible(dev, "lm75"))
                  wf_lm75_create(adapter, addr, 0, loc);
            /* ds1775 (compatible, better resolution */
            else if (of_device_is_compatible(dev, "ds1775"))
                  wf_lm75_create(adapter, addr, 1, loc);
      }
      return 0;
}

static int wf_lm75_detach(struct i2c_client *client)
{
      struct wf_lm75_sensor *lm = i2c_to_lm75(client);

      DBG("wf_lm75: i2c detatch called for %s\n", lm->sens.name);

      /* Mark client detached */
      lm->i2c.adapter = NULL;

      /* release sensor */
      wf_unregister_sensor(&lm->sens);

      return 0;
}

static int __init wf_lm75_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_lm75_driver);
}

static void __exit wf_lm75_sensor_exit(void)
{
      i2c_del_driver(&wf_lm75_driver);
}


module_init(wf_lm75_sensor_init);
module_exit(wf_lm75_sensor_exit);

MODULE_AUTHOR("Benjamin Herrenschmidt <benh@kernel.crashing.org>");
MODULE_DESCRIPTION("LM75 sensor objects for PowerMacs thermal control");
MODULE_LICENSE("GPL");


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