/* $Id: envctrl.c,v 1.25 2002/01/15 09:01:26 davem Exp $
 * envctrl.c: Temperature and Fan monitoring on Machines providing it.
 *
 * Copyright (C) 1998  Eddie C. Dost  (ecd@skynet.be)
 * Copyright (C) 2000  Vinh Truong    (vinh.truong@eng.sun.com)
 * VT - The implementation is to support Sun Microelectronics (SME) platform
 *      environment monitoring.  SME platforms use pcf8584 as the i2c bus 
 *      controller to access pcf8591 (8-bit A/D and D/A converter) and 
 *      pcf8571 (256 x 8-bit static low-voltage RAM with I2C-bus interface).
 *      At board level, it follows SME Firmware I2C Specification. Reference:
 *      http://www-eu2.semiconductors.com/pip/PCF8584P
 *      http://www-eu2.semiconductors.com/pip/PCF8574AP
 *      http://www-eu2.semiconductors.com/pip/PCF8591P
 *
 * EB - Added support for CP1500 Global Address and PS/Voltage monitoring.
 *              Eric Brower <ebrower@usa.net>
 *
 * DB - Audit every copy_to_user in envctrl_read.
 *              Daniele Bellucci <bellucda@tiscali.it>
 */

#include <linux/module.h>
#include <linux/init.h>
#include <linux/kthread.h>
#include <linux/delay.h>
#include <linux/ioport.h>
#include <linux/miscdevice.h>
#include <linux/kmod.h>
#include <linux/reboot.h>

#include <asm/ebus.h>
#include <asm/uaccess.h>
#include <asm/envctrl.h>
#include <asm/io.h>

#define ENVCTRL_MINOR   162

#define PCF8584_ADDRESS 0x55

#define CONTROL_PIN     0x80
#define CONTROL_ES0     0x40
#define CONTROL_ES1     0x20
#define CONTROL_ES2     0x10
#define CONTROL_ENI     0x08
#define CONTROL_STA     0x04
#define CONTROL_STO     0x02
#define CONTROL_ACK     0x01

#define STATUS_PIN      0x80
#define STATUS_STS      0x20
#define STATUS_BER      0x10
#define STATUS_LRB      0x08
#define STATUS_AD0      0x08
#define STATUS_AAB      0x04
#define STATUS_LAB      0x02
#define STATUS_BB       0x01

/*
 * CLK Mode Register.
 */
#define BUS_CLK_90      0x00
#define BUS_CLK_45      0x01
#define BUS_CLK_11      0x02
#define BUS_CLK_1_5     0x03

#define CLK_3           0x00
#define CLK_4_43        0x10
#define CLK_6           0x14
#define CLK_8           0x18
#define CLK_12          0x1c

#define OBD_SEND_START  0xc5    /* value to generate I2c_bus START condition */
#define OBD_SEND_STOP   0xc3    /* value to generate I2c_bus STOP condition */

/* Monitor type of i2c child device.
 * Firmware definitions.
 */
#define PCF8584_MAX_CHANNELS            8
#define PCF8584_GLOBALADDR_TYPE                 6  /* global address monitor */
#define PCF8584_FANSTAT_TYPE            3  /* fan status monitor */
#define PCF8584_VOLTAGE_TYPE            2  /* voltage monitor    */
#define PCF8584_TEMP_TYPE                       1  /* temperature monitor*/

/* Monitor type of i2c child device.
 * Driver definitions.
 */
#define ENVCTRL_NOMON                           0
#define ENVCTRL_CPUTEMP_MON                     1    /* cpu temperature monitor */
#define ENVCTRL_CPUVOLTAGE_MON          2    /* voltage monitor         */
#define ENVCTRL_FANSTAT_MON             3    /* fan status monitor      */
#define ENVCTRL_ETHERTEMP_MON           4    /* ethernet temperarture */
                                             /* monitor                     */
#define ENVCTRL_VOLTAGESTAT_MON         5    /* voltage status monitor  */
#define ENVCTRL_MTHRBDTEMP_MON          6    /* motherboard temperature */
#define ENVCTRL_SCSITEMP_MON            7    /* scsi temperarture */
#define ENVCTRL_GLOBALADDR_MON          8    /* global address */

/* Child device type.
 * Driver definitions.
 */
#define I2C_ADC                         0    /* pcf8591 */
#define I2C_GPIO                        1    /* pcf8571 */

/* Data read from child device may need to decode
 * through a data table and a scale.
 * Translation type as defined by firmware.
 */
#define ENVCTRL_TRANSLATE_NO            0
#define ENVCTRL_TRANSLATE_PARTIAL       1
#define ENVCTRL_TRANSLATE_COMBINED      2
#define ENVCTRL_TRANSLATE_FULL          3     /* table[data] */
#define ENVCTRL_TRANSLATE_SCALE         4     /* table[data]/scale */

/* Driver miscellaneous definitions. */
#define ENVCTRL_MAX_CPU                 4
#define CHANNEL_DESC_SZ                 256

/* Mask values for combined GlobalAddress/PowerStatus node */
#define ENVCTRL_GLOBALADDR_ADDR_MASK    0x1F
#define ENVCTRL_GLOBALADDR_PSTAT_MASK   0x60

/* Node 0x70 ignored on CompactPCI CP1400/1500 platforms 
 * (see envctrl_init_i2c_child)
 */
#define ENVCTRL_CPCI_IGNORED_NODE               0x70

#define PCF8584_DATA    0x00
#define PCF8584_CSR     0x01

/* Each child device can be monitored by up to PCF8584_MAX_CHANNELS.
 * Property of a port or channel as defined by the firmware.
 */
struct pcf8584_channel {
        unsigned char chnl_no;
        unsigned char io_direction;
        unsigned char type;
        unsigned char last;
};

/* Each child device may have one or more tables of bytes to help decode
 * data. Table property as defined by the firmware.
 */ 
struct pcf8584_tblprop {
        unsigned int type;
        unsigned int scale;  
        unsigned int offset; /* offset from the beginning of the table */
        unsigned int size;
};

/* i2c child */
struct i2c_child_t {
        /* Either ADC or GPIO. */
        unsigned char i2ctype;
        unsigned long addr;    
        struct pcf8584_channel chnl_array[PCF8584_MAX_CHANNELS];

        /* Channel info. */ 
        unsigned int total_chnls;       /* Number of monitor channels. */
        unsigned char fan_mask;         /* Byte mask for fan status channels. */
        unsigned char voltage_mask;     /* Byte mask for voltage status channels. */
        struct pcf8584_tblprop tblprop_array[PCF8584_MAX_CHANNELS];

        /* Properties of all monitor channels. */
        unsigned int total_tbls;        /* Number of monitor tables. */
        char *tables;                   /* Pointer to table(s). */
        char chnls_desc[CHANNEL_DESC_SZ]; /* Channel description. */
        char mon_type[PCF8584_MAX_CHANNELS];
};

static void __iomem *i2c;
static struct i2c_child_t i2c_childlist[ENVCTRL_MAX_CPU*2];
static unsigned char chnls_mask[] = { 0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80 };
static unsigned int warning_temperature = 0;
static unsigned int shutdown_temperature = 0;
static char read_cpu;

/* Forward declarations. */
static struct i2c_child_t *envctrl_get_i2c_child(unsigned char);

/* Function Description: Test the PIN bit (Pending Interrupt Not) 
 *                       to test when serial transmission is completed .
 * Return : None.
 */
static void envtrl_i2c_test_pin(void)
{
        int limit = 1000000;

        while (--limit > 0) {
                if (!(readb(i2c + PCF8584_CSR) & STATUS_PIN)) 
                        break;
                udelay(1);
        } 

        if (limit <= 0)
                printk(KERN_INFO "envctrl: Pin status will not clear.\n");
}

/* Function Description: Test busy bit.
 * Return : None.
 */
static void envctrl_i2c_test_bb(void)
{
        int limit = 1000000;

        while (--limit > 0) {
                /* Busy bit 0 means busy. */
                if (readb(i2c + PCF8584_CSR) & STATUS_BB)
                        break;
                udelay(1);
        } 

        if (limit <= 0)
                printk(KERN_INFO "envctrl: Busy bit will not clear.\n");
}

/* Function Description: Send the address for a read access.
 * Return : 0 if not acknowledged, otherwise acknowledged.
 */
static int envctrl_i2c_read_addr(unsigned char addr)
{
        envctrl_i2c_test_bb();

        /* Load address. */
        writeb(addr + 1, i2c + PCF8584_DATA);

        envctrl_i2c_test_bb();

        writeb(OBD_SEND_START, i2c + PCF8584_CSR);

        /* Wait for PIN. */
        envtrl_i2c_test_pin();

        /* CSR 0 means acknowledged. */
        if (!(readb(i2c + PCF8584_CSR) & STATUS_LRB)) {
                return readb(i2c + PCF8584_DATA);
        } else {
                writeb(OBD_SEND_STOP, i2c + PCF8584_CSR);
                return 0;
        }
}

/* Function Description: Send the address for write mode.  
 * Return : None.
 */
static void envctrl_i2c_write_addr(unsigned char addr)
{
        envctrl_i2c_test_bb();
        writeb(addr, i2c + PCF8584_DATA);

        /* Generate Start condition. */
        writeb(OBD_SEND_START, i2c + PCF8584_CSR);
}

/* Function Description: Read 1 byte of data from addr 
 *                       set by envctrl_i2c_read_addr() 
 * Return : Data from address set by envctrl_i2c_read_addr().
 */
static unsigned char envctrl_i2c_read_data(void)
{
        envtrl_i2c_test_pin();
        writeb(CONTROL_ES0, i2c + PCF8584_CSR);  /* Send neg ack. */
        return readb(i2c + PCF8584_DATA);
}

/* Function Description: Instruct the device which port to read data from.  
 * Return : None.
 */
static void envctrl_i2c_write_data(unsigned char port)
{
        envtrl_i2c_test_pin();
        writeb(port, i2c + PCF8584_DATA);
}

/* Function Description: Generate Stop condition after last byte is sent.
 * Return : None.
 */
static void envctrl_i2c_stop(void)
{
        envtrl_i2c_test_pin();
        writeb(OBD_SEND_STOP, i2c + PCF8584_CSR);
}

/* Function Description: Read adc device.
 * Return : Data at address and port.
 */
static unsigned char envctrl_i2c_read_8591(unsigned char addr, unsigned char port)
{
        /* Send address. */
        envctrl_i2c_write_addr(addr);

        /* Setup port to read. */
        envctrl_i2c_write_data(port);
        envctrl_i2c_stop();

        /* Read port. */
        envctrl_i2c_read_addr(addr);

        /* Do a single byte read and send stop. */
        envctrl_i2c_read_data();
        envctrl_i2c_stop();

        return readb(i2c + PCF8584_DATA);
}

/* Function Description: Read gpio device.
 * Return : Data at address.
 */
static unsigned char envctrl_i2c_read_8574(unsigned char addr)
{
        unsigned char rd;

        envctrl_i2c_read_addr(addr);

        /* Do a single byte read and send stop. */
        rd = envctrl_i2c_read_data();
        envctrl_i2c_stop();
        return rd;
}

/* Function Description: Decode data read from an adc device using firmware
 *                       table.
 * Return: Number of read bytes. Data is stored in bufdata in ascii format.
 */
static int envctrl_i2c_data_translate(unsigned char data, int translate_type,
                                      int scale, char *tbl, char *bufdata)
{
        int len = 0;

        switch (translate_type) {
        case ENVCTRL_TRANSLATE_NO:
                /* No decode necessary. */
                len = 1;
                bufdata[0] = data;
                break;

        case ENVCTRL_TRANSLATE_FULL:
                /* Decode this way: data = table[data]. */
                len = 1;
                bufdata[0] = tbl[data];
                break;

        case ENVCTRL_TRANSLATE_SCALE:
                /* Decode this way: data = table[data]/scale */
                sprintf(bufdata,"%d ", (tbl[data] * 10) / (scale));
                len = strlen(bufdata);
                bufdata[len - 1] = bufdata[len - 2];
                bufdata[len - 2] = '.';
                break;

        default:
                break;
        };

        return len;
}

/* Function Description: Read cpu-related data such as cpu temperature, voltage.
 * Return: Number of read bytes. Data is stored in bufdata in ascii format.
 */
static int envctrl_read_cpu_info(int cpu, struct i2c_child_t *pchild,
                                 char mon_type, unsigned char *bufdata)
{
        unsigned char data;
        int i;
        char *tbl, j = -1;

        /* Find the right monitor type and channel. */
        for (i = 0; i < PCF8584_MAX_CHANNELS; i++) {
                if (pchild->mon_type[i] == mon_type) {
                        if (++j == cpu) {
                                break;
                        }
                }
        }

        if (j != cpu)
                return 0;

        /* Read data from address and port. */
        data = envctrl_i2c_read_8591((unsigned char)pchild->addr,
                                     (unsigned char)pchild->chnl_array[i].chnl_no);

        /* Find decoding table. */
        tbl = pchild->tables + pchild->tblprop_array[i].offset;

        return envctrl_i2c_data_translate(data, pchild->tblprop_array[i].type,
                                          pchild->tblprop_array[i].scale,
                                          tbl, bufdata);
}

/* Function Description: Read noncpu-related data such as motherboard 
 *                       temperature.
 * Return: Number of read bytes. Data is stored in bufdata in ascii format.
 */
static int envctrl_read_noncpu_info(struct i2c_child_t *pchild,
                                    char mon_type, unsigned char *bufdata)
{
        unsigned char data;
        int i;
        char *tbl = NULL;

        for (i = 0; i < PCF8584_MAX_CHANNELS; i++) {
                if (pchild->mon_type[i] == mon_type)
                        break;
        }

        if (i >= PCF8584_MAX_CHANNELS)
                return 0;

        /* Read data from address and port. */
        data = envctrl_i2c_read_8591((unsigned char)pchild->addr,
                                     (unsigned char)pchild->chnl_array[i].chnl_no);

        /* Find decoding table. */
        tbl = pchild->tables + pchild->tblprop_array[i].offset;

        return envctrl_i2c_data_translate(data, pchild->tblprop_array[i].type,
                                          pchild->tblprop_array[i].scale,
                                          tbl, bufdata);
}

/* Function Description: Read fan status.
 * Return : Always 1 byte. Status stored in bufdata.
 */
static int envctrl_i2c_fan_status(struct i2c_child_t *pchild,
                                  unsigned char data,
                                  char *bufdata)
{
        unsigned char tmp, ret = 0;
        int i, j = 0;

        tmp = data & pchild->fan_mask;

        if (tmp == pchild->fan_mask) {
                /* All bits are on. All fans are functioning. */
                ret = ENVCTRL_ALL_FANS_GOOD;
        } else if (tmp == 0) {
                /* No bits are on. No fans are functioning. */
                ret = ENVCTRL_ALL_FANS_BAD;
        } else {
                /* Go through all channels, mark 'on' the matched bits.
                 * Notice that fan_mask may have discontiguous bits but
                 * return mask are always contiguous. For example if we
                 * monitor 4 fans at channels 0,1,2,4, the return mask
                 * should be 00010000 if only fan at channel 4 is working.
                 */
                for (i = 0; i < PCF8584_MAX_CHANNELS;i++) {
                        if (pchild->fan_mask & chnls_mask[i]) {
                                if (!(chnls_mask[i] & tmp))
                                        ret |= chnls_mask[j];

                                j++;
                        }
                }
        }

        bufdata[0] = ret;
        return 1;
}

/* Function Description: Read global addressing line.
 * Return : Always 1 byte. Status stored in bufdata.
 */
static int envctrl_i2c_globaladdr(struct i2c_child_t *pchild,
                                  unsigned char data,
                                  char *bufdata)
{
        /* Translatation table is not necessary, as global
         * addr is the integer value of the GA# bits.
         *
         * NOTE: MSB is documented as zero, but I see it as '1' always....
         *
         * -----------------------------------------------
         * | 0 | FAL | DEG | GA4 | GA3 | GA2 | GA1 | GA0 |
         * -----------------------------------------------
         * GA0 - GA4    integer value of Global Address (backplane slot#)
         * DEG                  0 = cPCI Power supply output is starting to degrade
         *                              1 = cPCI Power supply output is OK
         * FAL                  0 = cPCI Power supply has failed
         *                              1 = cPCI Power supply output is OK
         */
        bufdata[0] = (data & ENVCTRL_GLOBALADDR_ADDR_MASK);
        return 1;
}

/* Function Description: Read standard voltage and power supply status.
 * Return : Always 1 byte. Status stored in bufdata.
 */
static unsigned char envctrl_i2c_voltage_status(struct i2c_child_t *pchild,
                                                unsigned char data,
                                                char *bufdata)
{
        unsigned char tmp, ret = 0;
        int i, j = 0;

        tmp = data & pchild->voltage_mask;

        /* Two channels are used to monitor voltage and power supply. */
        if (tmp == pchild->voltage_mask) {
                /* All bits are on. Voltage and power supply are okay. */
                ret = ENVCTRL_VOLTAGE_POWERSUPPLY_GOOD;
        } else if (tmp == 0) {
                /* All bits are off. Voltage and power supply are bad */
                ret = ENVCTRL_VOLTAGE_POWERSUPPLY_BAD;
        } else {
                /* Either voltage or power supply has problem. */
                for (i = 0; i < PCF8584_MAX_CHANNELS; i++) {
                        if (pchild->voltage_mask & chnls_mask[i]) {
                                j++;

                                /* Break out when there is a mismatch. */
                                if (!(chnls_mask[i] & tmp))
                                        break; 
                        }
                }

                /* Make a wish that hardware will always use the
                 * first channel for voltage and the second for
                 * power supply.
                 */
                if (j == 1)
                        ret = ENVCTRL_VOLTAGE_BAD;
                else
                        ret = ENVCTRL_POWERSUPPLY_BAD;
        }

        bufdata[0] = ret;
        return 1;
}

/* Function Description: Read a byte from /dev/envctrl. Mapped to user read().
 * Return: Number of read bytes. 0 for error.
 */
static ssize_t
envctrl_read(struct file *file, char __user *buf, size_t count, loff_t *ppos)
{
        struct i2c_child_t *pchild;
        unsigned char data[10];
        int ret = 0;

        /* Get the type of read as decided in ioctl() call.
         * Find the appropriate i2c child.
         * Get the data and put back to the user buffer.
         */

        switch ((int)(long)file->private_data) {
        case ENVCTRL_RD_WARNING_TEMPERATURE:
                if (warning_temperature == 0)
                        return 0;

                data[0] = (unsigned char)(warning_temperature);
                ret = 1;
                if (copy_to_user(buf, data, ret))
                        ret = -EFAULT;
                break;

        case ENVCTRL_RD_SHUTDOWN_TEMPERATURE:
                if (shutdown_temperature == 0)
                        return 0;

                data[0] = (unsigned char)(shutdown_temperature);
                ret = 1;
                if (copy_to_user(buf, data, ret))
                        ret = -EFAULT;
                break;

        case ENVCTRL_RD_MTHRBD_TEMPERATURE:
                if (!(pchild = envctrl_get_i2c_child(ENVCTRL_MTHRBDTEMP_MON)))
                        return 0;
                ret = envctrl_read_noncpu_info(pchild, ENVCTRL_MTHRBDTEMP_MON, data);
                if (copy_to_user(buf, data, ret))
                        ret = -EFAULT;
                break;

        case ENVCTRL_RD_CPU_TEMPERATURE:
                if (!(pchild = envctrl_get_i2c_child(ENVCTRL_CPUTEMP_MON)))
                        return 0;
                ret = envctrl_read_cpu_info(read_cpu, pchild, ENVCTRL_CPUTEMP_MON, data);

                /* Reset cpu to the default cpu0. */
                if (copy_to_user(buf, data, ret))
                        ret = -EFAULT;
                break;

        case ENVCTRL_RD_CPU_VOLTAGE:
                if (!(pchild = envctrl_get_i2c_child(ENVCTRL_CPUVOLTAGE_MON)))
                        return 0;
                ret = envctrl_read_cpu_info(read_cpu, pchild, ENVCTRL_CPUVOLTAGE_MON, data);

                /* Reset cpu to the default cpu0. */
                if (copy_to_user(buf, data, ret))
                        ret = -EFAULT;
                break;

        case ENVCTRL_RD_SCSI_TEMPERATURE:
                if (!(pchild = envctrl_get_i2c_child(ENVCTRL_SCSITEMP_MON)))
                        return 0;
                ret = envctrl_read_noncpu_info(pchild, ENVCTRL_SCSITEMP_MON, data);
                if (copy_to_user(buf, data, ret))
                        ret = -EFAULT;
                break;

        case ENVCTRL_RD_ETHERNET_TEMPERATURE:
                if (!(pchild = envctrl_get_i2c_child(ENVCTRL_ETHERTEMP_MON)))
                        return 0;
                ret = envctrl_read_noncpu_info(pchild, ENVCTRL_ETHERTEMP_MON, data);
                if (copy_to_user(buf, data, ret))
                        ret = -EFAULT;
                break;

        case ENVCTRL_RD_FAN_STATUS:
                if (!(pchild = envctrl_get_i2c_child(ENVCTRL_FANSTAT_MON)))
                        return 0;
                data[0] = envctrl_i2c_read_8574(pchild->addr);
                ret = envctrl_i2c_fan_status(pchild,data[0], data);
                if (copy_to_user(buf, data, ret))
                        ret = -EFAULT;
                break;
        
        case ENVCTRL_RD_GLOBALADDRESS:
                if (!(pchild = envctrl_get_i2c_child(ENVCTRL_GLOBALADDR_MON)))
                        return 0;
                data[0] = envctrl_i2c_read_8574(pchild->addr);
                ret = envctrl_i2c_globaladdr(pchild, data[0], data);
                if (copy_to_user(buf, data, ret))
                        ret = -EFAULT;
                break;

        case ENVCTRL_RD_VOLTAGE_STATUS:
                if (!(pchild = envctrl_get_i2c_child(ENVCTRL_VOLTAGESTAT_MON)))
                        /* If voltage monitor not present, check for CPCI equivalent */
                        if (!(pchild = envctrl_get_i2c_child(ENVCTRL_GLOBALADDR_MON)))
                                return 0;
                data[0] = envctrl_i2c_read_8574(pchild->addr);
                ret = envctrl_i2c_voltage_status(pchild, data[0], data);
                if (copy_to_user(buf, data, ret))
                        ret = -EFAULT;
                break;

        default:
                break;

        };

        return ret;
}

/* Function Description: Command what to read.  Mapped to user ioctl().
 * Return: Gives 0 for implemented commands, -EINVAL otherwise.
 */
static long
envctrl_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
        char __user *infobuf;

        switch (cmd) {
        case ENVCTRL_RD_WARNING_TEMPERATURE:
        case ENVCTRL_RD_SHUTDOWN_TEMPERATURE:
        case ENVCTRL_RD_MTHRBD_TEMPERATURE:
        case ENVCTRL_RD_FAN_STATUS:
        case ENVCTRL_RD_VOLTAGE_STATUS:
        case ENVCTRL_RD_ETHERNET_TEMPERATURE:
        case ENVCTRL_RD_SCSI_TEMPERATURE:
        case ENVCTRL_RD_GLOBALADDRESS:
                file->private_data = (void *)(long)cmd;
                break;

        case ENVCTRL_RD_CPU_TEMPERATURE:
        case ENVCTRL_RD_CPU_VOLTAGE:
                /* Check to see if application passes in any cpu number,
                 * the default is cpu0.
                 */
                infobuf = (char __user *) arg;
                if (infobuf == NULL) {
                        read_cpu = 0;
                }else {
                        get_user(read_cpu, infobuf);
                }

                /* Save the command for use when reading. */
                file->private_data = (void *)(long)cmd;
                break;

        default:
                return -EINVAL;
        };

        return 0;
}

/* Function Description: open device. Mapped to user open().
 * Return: Always 0.
 */
static int
envctrl_open(struct inode *inode, struct file *file)
{
        file->private_data = NULL;
        return 0;
}

/* Function Description: Open device. Mapped to user close().
 * Return: Always 0.
 */
static int
envctrl_release(struct inode *inode, struct file *file)
{
        return 0;
}

static const struct file_operations envctrl_fops = {
        .owner =                THIS_MODULE,
        .read =                 envctrl_read,
        .unlocked_ioctl =       envctrl_ioctl,
#ifdef CONFIG_COMPAT
        .compat_ioctl =         envctrl_ioctl,
#endif
        .open =                 envctrl_open,
        .release =              envctrl_release,
};      

static struct miscdevice envctrl_dev = {
        ENVCTRL_MINOR,
        "envctrl",
        &envctrl_fops
};

/* Function Description: Set monitor type based on firmware description.
 * Return: None.
 */
static void envctrl_set_mon(struct i2c_child_t *pchild,
                            const char *chnl_desc,
                            int chnl_no)
{
        /* Firmware only has temperature type.  It does not distinguish
         * different kinds of temperatures.  We use channel description
         * to disinguish them.
         */
        if (!(strcmp(chnl_desc,"temp,cpu")) ||
            !(strcmp(chnl_desc,"temp,cpu0")) ||
            !(strcmp(chnl_desc,"temp,cpu1")) ||
            !(strcmp(chnl_desc,"temp,cpu2")) ||
            !(strcmp(chnl_desc,"temp,cpu3")))
                pchild->mon_type[chnl_no] = ENVCTRL_CPUTEMP_MON;

        if (!(strcmp(chnl_desc,"vddcore,cpu0")) ||
            !(strcmp(chnl_desc,"vddcore,cpu1")) ||
            !(strcmp(chnl_desc,"vddcore,cpu2")) ||
            !(strcmp(chnl_desc,"vddcore,cpu3")))
                pchild->mon_type[chnl_no] = ENVCTRL_CPUVOLTAGE_MON;

        if (!(strcmp(chnl_desc,"temp,motherboard")))
                pchild->mon_type[chnl_no] = ENVCTRL_MTHRBDTEMP_MON;

        if (!(strcmp(chnl_desc,"temp,scsi")))
                pchild->mon_type[chnl_no] = ENVCTRL_SCSITEMP_MON;

        if (!(strcmp(chnl_desc,"temp,ethernet")))
                pchild->mon_type[chnl_no] = ENVCTRL_ETHERTEMP_MON;
}

/* Function Description: Initialize monitor channel with channel desc,
 *                       decoding tables, monitor type, optional properties.
 * Return: None.
 */
static void envctrl_init_adc(struct i2c_child_t *pchild, struct device_node *dp)
{
        int i = 0, len;
        const char *pos;
        const unsigned int *pval;

        /* Firmware describe channels into a stream separated by a '\0'. */
        pos = of_get_property(dp, "channels-description", &len);

        while (len > 0) {
                int l = strlen(pos) + 1;
                envctrl_set_mon(pchild, pos, i++);
                len -= l;
                pos += l;
        }

        /* Get optional properties. */
        pval = of_get_property(dp, "warning-temp", NULL);
        if (pval)
                warning_temperature = *pval;

        pval = of_get_property(dp, "shutdown-temp", NULL);
        if (pval)
                shutdown_temperature = *pval;
}

/* Function Description: Initialize child device monitoring fan status.
 * Return: None.
 */
static void envctrl_init_fanstat(struct i2c_child_t *pchild)
{
        int i;

        /* Go through all channels and set up the mask. */
        for (i = 0; i < pchild->total_chnls; i++)
                pchild->fan_mask |= chnls_mask[(pchild->chnl_array[i]).chnl_no];

        /* We only need to know if this child has fan status monitored.
         * We don't care which channels since we have the mask already.
         */
        pchild->mon_type[0] = ENVCTRL_FANSTAT_MON;
}

/* Function Description: Initialize child device for global addressing line.
 * Return: None.
 */
static void envctrl_init_globaladdr(struct i2c_child_t *pchild)
{
        int i;

        /* Voltage/PowerSupply monitoring is piggybacked 
         * with Global Address on CompactPCI.  See comments
         * within envctrl_i2c_globaladdr for bit assignments.
         *
         * The mask is created here by assigning mask bits to each
         * bit position that represents PCF8584_VOLTAGE_TYPE data.
         * Channel numbers are not consecutive within the globaladdr
         * node (why?), so we use the actual counter value as chnls_mask
         * index instead of the chnl_array[x].chnl_no value.
         *
         * NOTE: This loop could be replaced with a constant representing
         * a mask of bits 5&6 (ENVCTRL_GLOBALADDR_PSTAT_MASK).
         */
        for (i = 0; i < pchild->total_chnls; i++) {
                if (PCF8584_VOLTAGE_TYPE == pchild->chnl_array[i].type) {
                        pchild->voltage_mask |= chnls_mask[i];
                }
        }

        /* We only need to know if this child has global addressing 
         * line monitored.  We don't care which channels since we know 
         * the mask already (ENVCTRL_GLOBALADDR_ADDR_MASK).
         */
        pchild->mon_type[0] = ENVCTRL_GLOBALADDR_MON;
}

/* Initialize child device monitoring voltage status. */
static void envctrl_init_voltage_status(struct i2c_child_t *pchild)
{
        int i;

        /* Go through all channels and set up the mask. */
        for (i = 0; i < pchild->total_chnls; i++)
                pchild->voltage_mask |= chnls_mask[(pchild->chnl_array[i]).chnl_no];

        /* We only need to know if this child has voltage status monitored.
         * We don't care which channels since we have the mask already.
         */
        pchild->mon_type[0] = ENVCTRL_VOLTAGESTAT_MON;
}

/* Function Description: Initialize i2c child device.
 * Return: None.
 */
static void envctrl_init_i2c_child(struct linux_ebus_child *edev_child,
                                   struct i2c_child_t *pchild)
{
        int len, i, tbls_size = 0;
        struct device_node *dp = edev_child->prom_node;
        const void *pval;

        /* Get device address. */
        pval = of_get_property(dp, "reg", &len);
        memcpy(&pchild->addr, pval, len);

        /* Get tables property.  Read firmware temperature tables. */
        pval = of_get_property(dp, "translation", &len);
        if (pval && len > 0) {
                memcpy(pchild->tblprop_array, pval, len);
                pchild->total_tbls = len / sizeof(struct pcf8584_tblprop);
                for (i = 0; i < pchild->total_tbls; i++) {
                        if ((pchild->tblprop_array[i].size + pchild->tblprop_array[i].offset) > tbls_size) {
                                tbls_size = pchild->tblprop_array[i].size + pchild->tblprop_array[i].offset;
                        }
                }

                pchild->tables = kmalloc(tbls_size, GFP_KERNEL);
                if (pchild->tables == NULL){
                        printk("envctrl: Failed to allocate table.\n");
                        return;
                }
                pval = of_get_property(dp, "tables", &len);
                if (!pval || len <= 0) {
                        printk("envctrl: Failed to get table.\n");
                        return;
                }
                memcpy(pchild->tables, pval, len);
        }

        /* SPARCengine ASM Reference Manual (ref. SMI doc 805-7581-04)
         * sections 2.5, 3.5, 4.5 state node 0x70 for CP1400/1500 is
         * "For Factory Use Only."
         *
         * We ignore the node on these platforms by assigning the
         * 'NULL' monitor type.
         */
        if (ENVCTRL_CPCI_IGNORED_NODE == pchild->addr) {
                struct device_node *root_node;
                int len;

                root_node = of_find_node_by_path("/");
                if (!strcmp(root_node->name, "SUNW,UltraSPARC-IIi-cEngine")) {
                        for (len = 0; len < PCF8584_MAX_CHANNELS; ++len) {
                                pchild->mon_type[len] = ENVCTRL_NOMON;
                        }
                        return;
                }
        }

        /* Get the monitor channels. */
        pval = of_get_property(dp, "channels-in-use", &len);
        memcpy(pchild->chnl_array, pval, len);
        pchild->total_chnls = len / sizeof(struct pcf8584_channel);

        for (i = 0; i < pchild->total_chnls; i++) {
                switch (pchild->chnl_array[i].type) {
                case PCF8584_TEMP_TYPE:
                        envctrl_init_adc(pchild, dp);
                        break;

                case PCF8584_GLOBALADDR_TYPE:
                        envctrl_init_globaladdr(pchild);
                        i = pchild->total_chnls;
                        break;

                case PCF8584_FANSTAT_TYPE:
                        envctrl_init_fanstat(pchild);
                        i = pchild->total_chnls;
                        break;

                case PCF8584_VOLTAGE_TYPE:
                        if (pchild->i2ctype == I2C_ADC) {
                                envctrl_init_adc(pchild,dp);
                        } else {
                                envctrl_init_voltage_status(pchild);
                        }
                        i = pchild->total_chnls;
                        break;

                default:
                        break;
                };
        }
}

/* Function Description: Search the child device list for a device.
 * Return : The i2c child if found. NULL otherwise.
 */
static struct i2c_child_t *envctrl_get_i2c_child(unsigned char mon_type)
{
        int i, j;

        for (i = 0; i < ENVCTRL_MAX_CPU*2; i++) {
                for (j = 0; j < PCF8584_MAX_CHANNELS; j++) {
                        if (i2c_childlist[i].mon_type[j] == mon_type) {
                                return (struct i2c_child_t *)(&(i2c_childlist[i]));
                        }
                }
        }
        return NULL;
}

static void envctrl_do_shutdown(void)
{
        static int inprog = 0;
        int ret;

        if (inprog != 0)
                return;

        inprog = 1;
        printk(KERN_CRIT "kenvctrld: WARNING: Shutting down the system now.\n");
        ret = orderly_poweroff(true);
        if (ret < 0) {
                printk(KERN_CRIT "kenvctrld: WARNING: system shutdown failed!\n"); 
                inprog = 0;  /* unlikely to succeed, but we could try again */
        }
}

static struct task_struct *kenvctrld_task;

static int kenvctrld(void *__unused)
{
        int poll_interval;
        int whichcpu;
        char tempbuf[10];
        struct i2c_child_t *cputemp;

        if (NULL == (cputemp = envctrl_get_i2c_child(ENVCTRL_CPUTEMP_MON))) {
                printk(KERN_ERR 
                       "envctrl: kenvctrld unable to monitor CPU temp-- exiting\n");
                return -ENODEV;
        }

        poll_interval = 5000; /* TODO env_mon_interval */

        printk(KERN_INFO "envctrl: %s starting...\n", current->comm);
        for (;;) {
                msleep_interruptible(poll_interval);

                if (kthread_should_stop())
                        break;
                
                for (whichcpu = 0; whichcpu < ENVCTRL_MAX_CPU; ++whichcpu) {
                        if (0 < envctrl_read_cpu_info(whichcpu, cputemp,
                                                      ENVCTRL_CPUTEMP_MON,
                                                      tempbuf)) {
                                if (tempbuf[0] >= shutdown_temperature) {
                                        printk(KERN_CRIT 
                                                "%s: WARNING: CPU%i temperature %i C meets or exceeds "\
                                                "shutdown threshold %i C\n", 
                                                current->comm, whichcpu, 
                                                tempbuf[0], shutdown_temperature);
                                        envctrl_do_shutdown();
                                }
                        }
                }
        }
        printk(KERN_INFO "envctrl: %s exiting...\n", current->comm);
        return 0;
}

static int __init envctrl_init(void)
{
        struct linux_ebus *ebus = NULL;
        struct linux_ebus_device *edev = NULL;
        struct linux_ebus_child *edev_child = NULL;
        int err, i = 0;

        for_each_ebus(ebus) {
                for_each_ebusdev(edev, ebus) {
                        if (!strcmp(edev->prom_node->name, "bbc")) {
                                /* If we find a boot-bus controller node,
                                 * then this envctrl driver is not for us.
                                 */
                                return -ENODEV;
                        }
                }
        }

        /* Traverse through ebus and ebus device list for i2c device and
         * adc and gpio nodes.
         */
        for_each_ebus(ebus) {
                for_each_ebusdev(edev, ebus) {
                        if (!strcmp(edev->prom_node->name, "i2c")) {
                                i2c = ioremap(edev->resource[0].start, 0x2);
                                for_each_edevchild(edev, edev_child) {
                                        if (!strcmp("gpio", edev_child->prom_node->name)) {
                                                i2c_childlist[i].i2ctype = I2C_GPIO;
                                                envctrl_init_i2c_child(edev_child, &(i2c_childlist[i++]));
                                        }
                                        if (!strcmp("adc", edev_child->prom_node->name)) {
                                                i2c_childlist[i].i2ctype = I2C_ADC;
                                                envctrl_init_i2c_child(edev_child, &(i2c_childlist[i++]));
                                        }
                                }
                                goto done;
                        }
                }
        }

done:
        if (!edev) {
                printk("envctrl: I2C device not found.\n");
                return -ENODEV;
        }

        /* Set device address. */
        writeb(CONTROL_PIN, i2c + PCF8584_CSR);
        writeb(PCF8584_ADDRESS, i2c + PCF8584_DATA);

        /* Set system clock and SCL frequencies. */ 
        writeb(CONTROL_PIN | CONTROL_ES1, i2c + PCF8584_CSR);
        writeb(CLK_4_43 | BUS_CLK_90, i2c + PCF8584_DATA);

        /* Enable serial interface. */
        writeb(CONTROL_PIN | CONTROL_ES0 | CONTROL_ACK, i2c + PCF8584_CSR);
        udelay(200);

        /* Register the device as a minor miscellaneous device. */
        err = misc_register(&envctrl_dev);
        if (err) {
                printk("envctrl: Unable to get misc minor %d\n",
                       envctrl_dev.minor);
                goto out_iounmap;
        }

        /* Note above traversal routine post-incremented 'i' to accommodate 
         * a next child device, so we decrement before reverse-traversal of
         * child devices.
         */
        printk("envctrl: initialized ");
        for (--i; i >= 0; --i) {
                printk("[%s 0x%lx]%s", 
                        (I2C_ADC == i2c_childlist[i].i2ctype) ? ("adc") : 
                        ((I2C_GPIO == i2c_childlist[i].i2ctype) ? ("gpio") : ("unknown")), 
                        i2c_childlist[i].addr, (0 == i) ? ("\n") : (" "));
        }

        kenvctrld_task = kthread_run(kenvctrld, NULL, "kenvctrld");
        if (IS_ERR(kenvctrld_task)) {
                err = PTR_ERR(kenvctrld_task);
                goto out_deregister;
        }

        return 0;

out_deregister:
        misc_deregister(&envctrl_dev);
out_iounmap:
        iounmap(i2c);
        for (i = 0; i < ENVCTRL_MAX_CPU * 2; i++)
                kfree(i2c_childlist[i].tables);

        return err;
}

static void __exit envctrl_cleanup(void)
{
        int i;

        kthread_stop(kenvctrld_task);

        iounmap(i2c);
        misc_deregister(&envctrl_dev);

        for (i = 0; i < ENVCTRL_MAX_CPU * 2; i++)
                kfree(i2c_childlist[i].tables);
}

module_init(envctrl_init);
module_exit(envctrl_cleanup);
MODULE_LICENSE("GPL");