/*
 * i8k.c -- Linux driver for accessing the SMM BIOS on Dell I8000 laptops
 *
 * Copyright (C) 2001  Massimo Dal Zotto <dz@debian.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, or (at your option) any
 * later version.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 */

#include <linux/module.h>
#include <linux/version.h>
#include <linux/types.h>
#include <linux/init.h>
#include <linux/proc_fs.h>
#include <asm/io.h>
#include <asm/uaccess.h>

#include <linux/i8k.h>

#define I8K_VERSION		"1.1 02/11/2001"
#define I8K_BIOS_SIGNATURE	"Dell System Inspiron 8000"
#define I8K_BIOS_SIGNATURE_ADDR 0x000ec000
#define I8K_BIOS_VERSION_OFFSET	32

#define I8K_SMM_FN_STATUS	0x0025
#define I8K_SMM_POWER_STATUS	0x0069
#define I8K_SMM_SET_FAN		0x01a3
#define I8K_SMM_GET_FAN		0x00a3
#define I8K_SMM_GET_SPEED	0x02a3
#define I8K_SMM_GET_TEMP	0x10a3
#define I8K_SMM_BIOS_VERSION	0x00a6

#define I8K_FAN_MULT		30
#define I8K_MAX_TEMP		127

#define I8K_FN_NONE		0x08
#define I8K_FN_UP		0x09
#define I8K_FN_DOWN		0x0a
#define I8K_FN_MUTE		0x0c

#define I8K_POWER_AC		0x05
#define I8K_POWER_BATTERY	0x01

#define I8K_TEMPERATURE_BUG	1

static char bios_version[4] = "?";
static char bios_machine_id[16] = "?";

int force = 0;

MODULE_AUTHOR("Massimo Dal Zotto (dz@debian.org)");
MODULE_DESCRIPTION("Driver for accessing the SMM BIOS on Dell I8000 laptops");
MODULE_LICENSE("GPL");
MODULE_PARM(force, "i");
MODULE_PARM_DESC(force, "Force loading without checking for an Inspiron 8000");

static ssize_t i8k_read(struct file *, char *, size_t, loff_t *);
static int i8k_ioctl(struct inode *, struct file *, unsigned int,
		     unsigned long);

static struct file_operations i8k_fops = {
    read:	i8k_read,
    ioctl:	i8k_ioctl,
};

typedef struct {
    unsigned int eax;
    unsigned int ebx __attribute__ ((packed));
    unsigned int ecx __attribute__ ((packed));
    unsigned int edx __attribute__ ((packed));
    unsigned int esi __attribute__ ((packed));
    unsigned int edi __attribute__ ((packed));
} SMMRegisters;

/*
 * Call the System Management Mode BIOS.
 */
static int i8k_smm(SMMRegisters *regs)
{
    int rc;

    asm("pushl %%eax\n\t" \
	"movl 0(%%eax),%%edx\n\t" \
	"push %%edx\n\t" \
	"movl 4(%%eax),%%ebx\n\t" \
	"movl 8(%%eax),%%ecx\n\t" \
	"movl 12(%%eax),%%edx\n\t" \
	"movl 16(%%eax),%%esi\n\t" \
	"movl 20(%%eax),%%edi\n\t" \
	"popl %%eax\n\t" \
	"out %%al,$0xb2\n\t" \
	"out %%al,$0x84\n\t" \
	"xchgl %%eax,(%%esp)\n\t"
	"movl %%ebx,4(%%eax)\n\t" \
	"movl %%ecx,8(%%eax)\n\t" \
	"movl %%edx,12(%%eax)\n\t" \
	"movl %%esi,16(%%eax)\n\t" \
	"movl %%edi,20(%%eax)\n\t" \
	"popl %%edx\n\t" \
	"movl %%edx,0(%%eax)\n\t" \
	"lahf\n\t" \
	"shrl $8,%%eax\n\t" \
	"andl $1,%%eax\n" \
	: "=a" (rc)
	: "a" (regs)
	: "%ebx", "%ecx", "%edx", "%esi", "%edi", "memory");

    if ((rc != 0) || ((regs->eax & 0xffff) == 0xffff)) {
	return -EINVAL;
    }

    return 0;
}

/*
 * Read the bios version. Return the version as an integer corresponding
 * to the ascii value, for example "A17" is returned as 0x00413137.
 */
static int i8k_get_bios_version(void)
{
    SMMRegisters regs = { 0, 0, 0, 0, 0, 0 };
    int rc;

    regs.eax = I8K_SMM_BIOS_VERSION;
    if ((rc=i8k_smm(&regs)) < 0) {
	return rc;
    }

    return regs.eax;
}

/*
 * Read the machine id. Not yet implemented.
 */
static int i8k_get_machine_id(unsigned char *buff)
{
    return -EINVAL;
}

/*
 * Read the Fn key status.
 */
static int i8k_get_fn_status(void)
{
    SMMRegisters regs = { 0, 0, 0, 0, 0, 0 };
    int rc;

    regs.eax = I8K_SMM_FN_STATUS;
    if ((rc=i8k_smm(&regs)) < 0) {
	return rc;
    }

    switch ((regs.eax & 0xff00) >> 8) {
    case I8K_FN_UP:
	return I8K_VOL_UP;
    case I8K_FN_DOWN:
	return I8K_VOL_DOWN;
    case I8K_FN_MUTE:
	return I8K_VOL_MUTE;
    default:
	return 0;
    }
}

/*
 * Read the power status.
 */
static int i8k_get_power_status(void)
{
    SMMRegisters regs = { 0, 0, 0, 0, 0, 0 };
    int rc;

    regs.eax = I8K_SMM_POWER_STATUS;
    if ((rc=i8k_smm(&regs)) < 0) {
	return rc;
    }

    switch (regs.eax & 0xff) {
    case I8K_POWER_AC:
	return I8K_AC;
    default:
	return I8K_BATTERY;
    }
}

/*
 * Read the fan status.
 */
static int i8k_get_fan_status(int fan)
{
    SMMRegisters regs = { 0, 0, 0, 0, 0, 0 };
    int rc;

    regs.eax = I8K_SMM_GET_FAN;
    regs.ebx = fan & 0xff;
    if ((rc=i8k_smm(&regs)) < 0) {
	return rc;
    }

    return (regs.eax & 0xff);
}

/*
 * Read the fan speed in RPM.
 */
static int i8k_get_fan_speed(int fan)
{
    SMMRegisters regs = { 0, 0, 0, 0, 0, 0 };
    int rc;

    regs.eax = I8K_SMM_GET_SPEED;
    regs.ebx = fan & 0xff;
    if ((rc=i8k_smm(&regs)) < 0) {
	return rc;
    }

    return (regs.eax & 0xffff) * I8K_FAN_MULT;
}

/*
 * Set the fan speed (off, low, high). Returns the new fan status.
 */
static int i8k_set_fan(int fan, int speed)
{
    SMMRegisters regs = { 0, 0, 0, 0, 0, 0 };
    int rc;

    speed = (speed < 0) ? 0 : ((speed > I8K_FAN_MAX) ? I8K_FAN_MAX : speed);

    regs.eax = I8K_SMM_SET_FAN;
    regs.ebx = (fan & 0xff) | (speed << 8);
    if ((rc=i8k_smm(&regs)) < 0) {
	return rc;
    }

    return (i8k_get_fan_status(fan));
}

/*
 * Read the cpu temperature.
 */
static int i8k_get_cpu_temp(void)
{
    SMMRegisters regs = { 0, 0, 0, 0, 0, 0 };
    int rc;
    int temp;

#ifdef I8K_TEMPERATURE_BUG
    static int prev = 0;
#endif

    regs.eax = I8K_SMM_GET_TEMP;
    if ((rc=i8k_smm(&regs)) < 0) {
	return rc;
    }
    temp = regs.eax & 0xff;

#ifdef I8K_TEMPERATURE_BUG
    /*
     * Sometimes the temperature sensor returns 0x99, which is out of range.
     * In this case we return (once) the previous cached value. For example:
     # 1003655137 00000058 00005a4b
     # 1003655138 00000099 00003a80 <--- 0x99 = 153 degrees
     # 1003655139 00000054 00005c52
     */
    if (temp > I8K_MAX_TEMP) {
	temp = prev;
	prev = I8K_MAX_TEMP;
    } else {
	prev = temp;
    }
#endif

    return temp;
}

static int i8k_ioctl(struct inode *ip, struct file *fp, unsigned int cmd,
		     unsigned long arg)
{
    int val;
    int speed;
    unsigned char buff[16];

    if (!arg) {
	return -EINVAL;
    }

    switch (cmd) {
    case I8K_BIOS_VERSION:
	val = i8k_get_bios_version();
	break;

    case I8K_MACHINE_ID:
	memset(buff, 0, 16);
	val = i8k_get_machine_id(buff);
	break;

    case I8K_FN_STATUS:
	val = i8k_get_fn_status();
	break;

    case I8K_POWER_STATUS:
	val = i8k_get_power_status();
	break;

    case I8K_GET_TEMP:
	val = i8k_get_cpu_temp();
	break;

    case I8K_GET_SPEED:
	if (copy_from_user(&val, (int *)arg, sizeof(int))) {
	    return -EFAULT;
	}
	val = i8k_get_fan_speed(val);
	break;

    case I8K_GET_FAN:
	if (copy_from_user(&val, (int *)arg, sizeof(int))) {
	    return -EFAULT;
	}
	val = i8k_get_fan_status(val);
	break;

    case I8K_SET_FAN:
	if (copy_from_user(&val, (int *)arg, sizeof(int))) {
	    return -EFAULT;
	}
	if (copy_from_user(&speed, (int *)arg+1, sizeof(int))) {
	    return -EFAULT;
	}
	val = i8k_set_fan(val, speed);
	break;

    default:
	return -EINVAL;
    }

    if (val < 0) {
	return val;
    }

    switch (cmd) {
    case I8K_BIOS_VERSION:
	if (copy_to_user((int *)arg, &val, 4)) {
	    return -EFAULT;
	}
	break;
    case I8K_MACHINE_ID:
	if (copy_to_user((int *)arg, buff, 16)) {
	    return -EFAULT;
	}
	break;
    default:
	if (copy_to_user((int *)arg, &val, sizeof(int))) {
	    return -EFAULT;
	}
	break;
    }

    return 0;
}

/*
 * Print the information for /proc/i8k.
 */
static int i8k_get_info(char *buffer, char **start, off_t fpos, int length)
{
    int n, fn_key, cpu_temp, ac_power;
    int left_fan, right_fan, left_speed, right_speed;

    cpu_temp    = i8k_get_cpu_temp();
    left_fan    = i8k_get_fan_status(I8K_FAN_LEFT);
    right_fan   = i8k_get_fan_status(I8K_FAN_RIGHT);
    left_speed  = i8k_get_fan_speed(I8K_FAN_LEFT);
    right_speed = i8k_get_fan_speed(I8K_FAN_RIGHT);
    ac_power    = i8k_get_power_status();
    fn_key      = i8k_get_fn_status();

    /*
     * Info:
     *
     * 1)  Format version (this will change if format changes)
     * 2)  BIOS version
     * 3)  BIOS machine ID
     * 4)  Cpu temperature
     * 5)  Left fan status
     * 6)  Right fan status
     * 7)  Left fan speed
     * 8)  Right fan speed
     * 9)  AC power
     * 10) Fn Key status
     */
    n = sprintf(buffer, "%s %s %s %d %d %d %d %d %d %d\n",
		I8K_PROC_FMT,
		bios_version,
		bios_machine_id,
		cpu_temp,
		left_fan,
		right_fan,
		left_speed,
		right_speed,
		ac_power,
		fn_key);

    return n;
}

static ssize_t i8k_read(struct file *f, char *buffer, size_t len, loff_t *fpos)
{
    int n;
    char info[128];

    n = i8k_get_info(info, NULL, 0, 128);
    if (n <= 0) {
	return n;
    }

    if (*fpos >= n) {
	return 0;
    }

    if ((*fpos + len) >= n) {
	len = n - *fpos;
    }

    if (copy_to_user(buffer, info, len) != 0) {
	return -EFAULT;
    }

    *fpos += len;
    return len;
}

/*
 * Probe for the presence of an Inspiron I8000.
 */
static int i8k_probe(void)
{
    unsigned char *buff, *p;
    unsigned char bios_vers[4];
    int version;

    /*
     * Until Dell tell us how to reliably check for an Inspiron system
     * look for a signature at a fixed location in the BIOS memory.
     * Ugly but safe.
     */
    if (!force) {
	buff = ioremap(I8K_BIOS_SIGNATURE_ADDR, I8K_BIOS_VERSION_OFFSET+4);
	if (buff == NULL) {
	    printk("i8k: ioremap failed\n");
	    return -ENODEV;
	}
	if (strncmp(buff,I8K_BIOS_SIGNATURE,sizeof(I8K_BIOS_SIGNATURE)) != 0) {
	    printk("i8k: Inspiron 8000 BIOS signature not found\n");
	    iounmap(buff);
	    return -ENODEV;
	}
	strncpy(bios_vers, buff+I8K_BIOS_VERSION_OFFSET, 3);
	bios_vers[3] = '\0';
	iounmap(buff);
    }
    if (force >= 2) {
	buff = ioremap(0x000c0000, 0x00100000-0x000c0000);
	if (buff == NULL) {
	    printk("i8k: ioremap failed\n");
	    return -ENODEV;
	}
	for (p=buff; (p-buff)<(0x00100000-0x000c0000); p+=16) {
	    if (strncmp(p,I8K_BIOS_SIGNATURE,sizeof(I8K_BIOS_SIGNATURE))==0) {
		printk("i8k: Inspiron 8000 BIOS signature found at %08x\n",
		       0x000c0000+(p-buff));
		break;
	    }
	}
	iounmap(buff);
    }

    /*
     * Next try to get the BIOS version with an SMM call. If this
     * fails SMM can't be reliably used on this system.
     */
    version = i8k_get_bios_version();
    if (version <= 0) {
	printk("i8k: unable to get BIOS version\n");
	return -ENODEV;
    }
    bios_version[0] = (version >> 16) & 0xff;
    bios_version[1] = (version >>  8) & 0xff;
    bios_version[2] = (version)       & 0xff;
    bios_version[3] = '\0';

    /*
     * Finally check if the two versions match.
     */
    if (!force) {
	if (strncmp(bios_version,bios_vers,sizeof(bios_version)) != 0) {
	    printk("i8k: BIOS version mismatch: %s != %s\n",
		   bios_version, bios_vers);
	    return -ENODEV;
	}
    }

    return 0;
}

#ifdef MODULE
static
#endif
int __init i8k_init(void)
{
    struct proc_dir_entry *proc_i8k;

    /* Are we running on an Inspiron 8000 laptop? */
    if (i8k_probe() != 0) {
	return -ENODEV;
    }

    /* Register the proc entry */
    proc_i8k = create_proc_info_entry("i8k", 0, NULL, i8k_get_info);
    if (!proc_i8k) {
	return -ENOENT;
    }
    proc_i8k->proc_fops = &i8k_fops;
    SET_MODULE_OWNER(proc_i8k);

    printk(KERN_INFO
	   "Inspiron 8000 SMM driver v%s Massimo Dal Zotto (dz@debian.org)\n",
	   I8K_VERSION);

    return 0;
}

#ifdef MODULE
int init_module(void)
{
    return i8k_init();
}

void cleanup_module(void)
{
    /* Remove the proc entry */
    remove_proc_entry("i8k", NULL);

    printk(KERN_INFO "i8k: module unloaded\n");
}
#endif

/* end of file */