/*
 * 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 if (!strcmp(loc, "Incoming Air Temp"))
                lm->sens.name = "incoming-air-temp";
        else if (!strcmp(loc, "ODD Temp"))
                lm->sens.name = "optical-drive-temp";
        else if (!strcmp(loc, "HD Temp"))
                lm->sens.name = "hard-drive-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");