/* * Interrupt handling in Real-Time. Play sounds with PC speaker. * Signal version * * (C) Michael Barabanov, 1997 *  (C) FSMLabs  1999. baraban@fsmlabs.com *  Released under the GNU GENERAL PUBLIC LICENSE Version 2, June 1991 *  Any use of this code must include this notice. * */#include <linux/mc146818rtc.h>#include <rtl_fifo.h>#include <rtl_core.h>#include <rtl_time.h>#include <rtl.h>#include <signal.h>#include <sys/utsname.h>#include <time.h>#define FIFO_NO 3#define RTC_IRQ 8static int filter(int x){	static int oldx;	int ret;	if (x & 0x80) {		x = 382 - x;	}	ret = x > oldx;	oldx = x;	return ret;	}void intr_handler(int sig) {	char data;	char temp; 	(void) CMOS_READ(RTC_REG_C);        /* clear IRQ */ 	if (rtf_get(FIFO_NO, &data, 1) > 0) {		data = filter(data);/* 		if (data) conpr("1"); else conpr("0"); */		temp = inb(0x61);            		temp &= 0xfc;		if (data) {			temp |= 3;		}		outb(temp,0x61);	}	rtl_hard_enable_irq (RTC_IRQ);}char save_cmos_A;char save_cmos_B;int init_module(void){	char ctemp;	int ret;	time_t t;	struct utsname name;	ret = uname(&name);/* 	rtl_printf("sysname %s, version %s\n", name.sysname, name.version); */	t = time(NULL);/* 	rtl_printf("time() returned %d\n", t); */	if (!I8253_channel2_free()) {		conpr("RTLinux sound: can't use channel 2; bailing out\n");		return -1;	}	rtf_create(FIFO_NO, 4000);	/* this is just to ensure that the output of the counter is 1 */	outb_p(0xb0, 0x43);	/* binary, mode 0, LSB/MSB, ch 2 */	outb_p(0x1, 0x42);	outb_p(0x0, 0x42);	{		struct sigaction act;		act.sa_handler = intr_handler;		act.sa_flags = SA_FOCUS;		act.sa_focus = 1 << rtl_getcpuid();		sigaction (RTL_SIGIRQMIN + RTC_IRQ, &act, NULL);	}	/* program the RTC to interrupt at 8192 Hz */	save_cmos_A = CMOS_READ(RTC_REG_A);	save_cmos_B = CMOS_READ(RTC_REG_B);	CMOS_WRITE(0x23, RTC_REG_A);  	/* 32kHz Time Base, 8192 Hz interrupt frequency */	ctemp = CMOS_READ(RTC_REG_B);	ctemp &= 0x8f;                	/* Clear */	ctemp |= 0x40;                	/* Periodic interrupt enable */	CMOS_WRITE(ctemp, RTC_REG_B); 	rtl_hard_enable_irq (RTC_IRQ);	(void) CMOS_READ(RTC_REG_C);	return 0;} void cleanup_module(void){	rtf_destroy(FIFO_NO);	outb_p(0xb6, 0x43);	/* restore the original mode */	CMOS_WRITE(save_cmos_A, RTC_REG_A);	CMOS_WRITE(save_cmos_B, RTC_REG_B);	{		struct sigaction act;		act.sa_handler = SIG_IGN;		act.sa_flags = 0;		sigaction (RTL_SIGIRQMIN + RTC_IRQ, &act, NULL);	}}