h8.c

讲述linux的初始化过程

	case H8_RECAL_PTR:
	case H8_SET_INT_BATT_PERCENT:
	case H8_WRT_CFG_INTERFACE_REG:
	case H8_WRT_EVENT_STATUS_MASK:
	case H8_ENTER_POST_MODE:
	case H8_EXIT_POST_MODE:
	case H8_RD_EEPROM:
	case H8_WRT_EEPROM:
	case H8_WRT_TO_STATUS_DISP:
	    printk("H8: Write IO status display command done\n");
	    break;

	case H8_DEFINE_SPC_CHAR:
	case H8_DEFINE_TABLE_STRING_ENTRY:
	case H8_PERFORM_EMU_CMD:
	case H8_EMU_RD_REG:
	case H8_EMU_WRT_REG:
	case H8_EMU_RD_RAM:
	case H8_EMU_WRT_RAM:
	case H8_BQ_RD_REG:
	case H8_BQ_WRT_REG:
	case H8_PWR_OFF:
	    printk ("H8: misc command completed\n");
	    break;
        }
        return;
}

/*
 * Retrieve the current CPU temperature and case temperature.  Provides
 * the feedback for the thermal control algorithm.  Synchcronized via 
 * sleep() for priority so that no other actions in the process will take
 * place before the data becomes available.
 */
int
h8_get_curr_temp(u_char curr_temp[])
{
        u_char  buf[H8_MAX_CMD_SIZE];
        unsigned long flags;

        memset(buf, 0, H8_MAX_CMD_SIZE); 
        buf[0] = H8_RD_CURR_TEMP;

        h8_q_cmd(buf, 1, 2);

	save_flags(flags); cli();

        while((h8_sync_channel & H8_RD_CURR_TEMP) == 0)
                sleep_on(&h8_sync_wait); 

        restore_flags(flags);

        h8_sync_channel &= ~H8_RD_CURR_TEMP;
        curr_temp[0] = xx.byte[0];
        curr_temp[1] = xx.byte[1];
        xx.word = 0;

        if(h8_debug & 0x8) 
                printk("H8: curr CPU temp %d, Sys temp %d\n",
		       curr_temp[0], curr_temp[1]);
        return 0;
}

static void
h8_get_max_temp(void)
{
        u_char  buf[H8_MAX_CMD_SIZE];

        buf[0] = H8_RD_MAX_TEMP;
        h8_q_cmd(buf, 1, 2);
}

/*
 * Assigns an upper limit to the value of the H8 thermal interrupt.
 * As an example setting a value of 115 F here will cause the 
 * interrupt to trigger when the CPU temperature reaches 115 F.
 */
static void
h8_set_upper_therm_thold(int thold)
{
        u_char  buf[H8_MAX_CMD_SIZE];

        /* write 0 to reinitialize interrupt */
        buf[0] = H8_CTL_UPPER_TEMP;
        buf[1] = 0x0;
        buf[2] = 0x0;
        h8_q_cmd(buf, 3, 1); 

        /* Do it for real */
        buf[0] = H8_CTL_UPPER_TEMP;
        buf[1] = 0x0;
        buf[2] = thold;
        h8_q_cmd(buf, 3, 1); 
}

static void
h8_get_upper_therm_thold(void)
{
        u_char  buf[H8_MAX_CMD_SIZE];

        buf[0] = H8_CTL_UPPER_TEMP;
        buf[1] = 0xff;
        buf[2] = 0;
        h8_q_cmd(buf, 3, 1); 
}

/*
 * The external status word contains information on keyboard controller,
 * power button, changes in external batt status, change in DC state,
 * docking station, etc. General purpose querying use.
 */
int
h8_get_ext_status(u_char stat_word[])
{
        u_char  buf[H8_MAX_CMD_SIZE];
	unsigned long flags;

        memset(buf, 0, H8_MAX_CMD_SIZE); 
        buf[0] = H8_RD_EXT_STATUS;

        h8_q_cmd(buf, 1, 2);

	save_flags(flags); cli();

        while((h8_sync_channel & H8_GET_EXT_STATUS) == 0)
                sleep_on(&h8_sync_wait); 

        restore_flags(flags);

        h8_sync_channel &= ~H8_GET_EXT_STATUS;
        stat_word[0] = xx.byte[0];
        stat_word[1] = xx.byte[1];
        xx.word = 0;

        if(h8_debug & 0x8) 
                printk("H8: curr ext status %x,  %x\n",
		       stat_word[0], stat_word[1]);

        return 0;
}

/*
 * Thread attached to task 0 manages thermal/physcial state of Alphabook. 
 * When a condition is detected by the interrupt service routine, the
 * isr does a wakeup() on h8_monitor_wait.  The mask value is then
 * screened for the appropriate action.
 */

int
h8_monitor_thread(void * unused)
{
        u_char curr_temp[2];

        /*
         * Need a logic based safety valve here. During boot when this thread is
         * started and the thermal interrupt is not yet initialized this logic 
         * checks the temperature and acts accordingly.  When this path is acted
         * upon system boot is painfully slow, however, the priority associated 
         * with overheating is high enough to warrant this action.
         */
        h8_get_curr_temp(curr_temp);

        printk("H8: Initial CPU temp: %d\n", curr_temp[0]);

        if(curr_temp[0] >= h8_uthermal_threshold) {
                h8_set_event_mask(H8_MANAGE_UTHERM);
                h8_manage_therm();
        } else {
                /*
                 * Arm the upper thermal limit of the H8 so that any temp in
                 * excess will trigger the thermal control mechanism.
                 */
                h8_set_upper_therm_thold(h8_uthermal_threshold);
        }

        for(;;) {
		sleep_on(&h8_monitor_wait);

                if(h8_debug & 0x2)
                        printk("h8_monitor_thread awakened, mask:%x\n",
                                h8_event_mask);

                if (h8_event_mask & (H8_MANAGE_UTHERM|H8_MANAGE_LTHERM)) {
                        h8_manage_therm();
                }

#if 0
                if (h8_event_mask & H8_POWER_BUTTON) {
                        h8_system_down();
                }

		/*
		 * If an external DC supply is removed or added make 
		 * appropriate CPU speed adjustments.
		 */
                if (h8_event_mask & H8_MANAGE_BATTERY) {
                          h8_run_level_3_manage(H8_RUN); 
                          h8_clear_event_mask(H8_MANAGE_BATTERY);
                }
#endif
        }
}

/* 
 * Function implements the following policy. When the machine is booted
 * the system is set to run at full clock speed. When the upper thermal
 * threshold is reached as a result of full clock a damping factor is 
 * applied to cool off the cpu.  The default value is one quarter clock
 * (57 Mhz).  When as a result of this cooling a temperature lower by
 * hmc_uthermal_window is reached, the machine is reset to a higher 
 * speed, one half clock (115 Mhz).  One half clock is maintained until
 * the upper thermal threshold is again reached restarting the cycle.
 */

int
h8_manage_therm(void)
{
        u_char curr_temp[2];

        if(h8_event_mask & H8_MANAGE_UTHERM) {
		/* Upper thermal interrupt received, need to cool down. */
		if(h8_debug & 0x10)
                        printk("H8: Thermal threshold %d F reached\n",
			       h8_uthermal_threshold);
		h8_set_cpu_speed(h8_udamp); 
                h8_clear_event_mask(H8_MANAGE_UTHERM);
                h8_set_event_mask(H8_MANAGE_LTHERM);
                /* Check again in 30 seconds for CPU temperature */
                h8_start_monitor_timer(H8_TIMEOUT_INTERVAL); 
        } else if (h8_event_mask & H8_MANAGE_LTHERM) {
		/* See how cool the system has become as a result
		   of the reduction in speed. */
                h8_get_curr_temp(curr_temp);
                last_temp = curr_temp[0];
                if (curr_temp[0] < (h8_uthermal_threshold - h8_uthermal_window))
		{
			/* System cooling has progressed to a point
			   that the CPU may be sped up. */
                        h8_set_upper_therm_thold(h8_uthermal_threshold);
                        h8_set_cpu_speed(h8_ldamp); /* adjustable */ 
                        if(h8_debug & 0x10)
                            printk("H8: CPU cool, applying cpu_divisor: %d \n",
				   h8_ldamp);
                        h8_clear_event_mask(H8_MANAGE_LTHERM);
                }
		else /* Not cool enough yet, check again in 30 seconds. */
                        h8_start_monitor_timer(H8_TIMEOUT_INTERVAL);
        } else {
                
        }
	return 0;
}

/* 
 * Function conditions the value of global_rpb_counter before
 * calling the primitive which causes the actual speed change.
 */
void
h8_set_cpu_speed(int speed_divisor)
{

#ifdef NOT_YET
/*
 * global_rpb_counter is consumed by alpha_delay() in determining just
 * how much time to delay.  It is necessary that the number of microseconds
 * in DELAY(n) be kept consistent over a variety of CPU clock speeds.
 * To that end global_rpb_counter is here adjusted.
 */ 
        
        switch (speed_divisor) {
                case 0:
                        global_rpb_counter = rpb->rpb_counter * 2L;
                        break;
                case 1:
                        global_rpb_counter = rpb->rpb_counter * 4L / 3L ;
                        break;
                case 3:
                        global_rpb_counter = rpb->rpb_counter / 2L;
                        break;
                case 4:
                        global_rpb_counter = rpb->rpb_counter / 4L;
                        break;
                case 5:
                        global_rpb_counter = rpb->rpb_counter / 8L;
                        break;
                /* 
                 * This case most commonly needed for cpu_speed_divisor 
                 * of 2 which is the value assigned by the firmware. 
                 */
                default:
                        global_rpb_counter = rpb->rpb_counter;
                break;
        }
#endif /* NOT_YET */

        if(h8_debug & 0x8)
                printk("H8: Setting CPU speed to %d MHz\n",
		       speed_tab[speed_divisor]); 

         /* Make the actual speed change */
        lca_clock_fiddle(speed_divisor);
}

/*
 * Gets value stored in rpb representing CPU clock speed and adjusts this
 * value based on the current clock speed divisor.
 */
u_long
h8_get_cpu_speed(void)
{
        u_long speed = 0;
        u_long counter;

#ifdef NOT_YET
        counter = rpb->rpb_counter / 1000000L;

        switch (alphabook_get_clock()) {
                case 0:
                        speed = counter * 2L;
                        break;
                case 1:
                        speed = counter * 4L / 3L ;
                        break;
                case 2:
                        speed = counter;
                        break;
                case 3:
                        speed = counter / 2L;
                        break;
                case 4:
                        speed = counter / 4L;
                        break;
                case 5:
                        speed = counter / 8L;
                        break;
                default:
                break;
        }
        if(h8_debug & 0x8)
                printk("H8: CPU speed current setting: %d MHz\n", speed); 
#endif  /* NOT_YET */
	return speed;
}

static void
h8_activate_monitor(unsigned long unused)
{
	unsigned long flags;

	save_flags(flags); cli();
	h8_monitor_timer_active = 0;
	restore_flags(flags);

	wake_up(&h8_monitor_wait);
}

static void
h8_start_monitor_timer(unsigned long secs)
{
	unsigned long flags;

	if (h8_monitor_timer_active)
	    return;

	save_flags(flags); cli();
	h8_monitor_timer_active = 1;
	restore_flags(flags);

        init_timer(&h8_monitor_timer);
        h8_monitor_timer.function = h8_activate_monitor;
        h8_monitor_timer.expires = secs * HZ + jiffies;
        add_timer(&h8_monitor_timer);
}

static void h8_set_event_mask(int mask)
{
	unsigned long flags;

	save_flags(flags); cli();
	h8_event_mask |= mask;
	restore_flags(flags);
}

static void h8_clear_event_mask(int mask)
{
	unsigned long flags;

	save_flags(flags); cli();
	h8_event_mask &= (~mask);
	restore_flags(flags);
}