1 /* 2 * DEC I/O ASIC's counter clocksource 3 * 4 * Copyright (C) 2008 Yoichi Yuasa <yuasa@linux-mips.org> 5 * 6 * This program is free software; you can redistribute it and/or modify 7 * it under the terms of the GNU General Public License as published by 8 * the Free Software Foundation; either version 2 of the License, or 9 * (at your option) any later version. 10 * 11 * This program is distributed in the hope that it will be useful, 12 * but WITHOUT ANY WARRANTY; without even the implied warranty of 13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 14 * GNU General Public License for more details. 15 */ 16 #include <linux/clocksource.h> 17 #include <linux/init.h> 18 19 #include <asm/ds1287.h> 20 #include <asm/time.h> 21 #include <asm/dec/ioasic.h> 22 #include <asm/dec/ioasic_addrs.h> 23 24 static cycle_t dec_ioasic_hpt_read(struct clocksource *cs) 25 { 26 return ioasic_read(IO_REG_FCTR); 27 } 28 29 static struct clocksource clocksource_dec = { 30 .name = "dec-ioasic", 31 .read = dec_ioasic_hpt_read, 32 .mask = CLOCKSOURCE_MASK(32), 33 .flags = CLOCK_SOURCE_IS_CONTINUOUS, 34 }; 35 36 int __init dec_ioasic_clocksource_init(void) 37 { 38 unsigned int freq; 39 u32 start, end; 40 int i = HZ / 8; 41 42 ds1287_timer_state(); 43 while (!ds1287_timer_state()) 44 ; 45 46 start = dec_ioasic_hpt_read(&clocksource_dec); 47 48 while (i--) 49 while (!ds1287_timer_state()) 50 ; 51 52 end = dec_ioasic_hpt_read(&clocksource_dec); 53 54 freq = (end - start) * 8; 55 56 /* An early revision of the I/O ASIC didn't have the counter. */ 57 if (!freq) 58 return -ENXIO; 59 60 printk(KERN_INFO "I/O ASIC clock frequency %dHz\n", freq); 61 62 clocksource_dec.rating = 200 + freq / 10000000; 63 clocksource_register_hz(&clocksource_dec, freq); 64 return 0; 65 } 66