| 1 | // SPDX-License-Identifier: GPL-2.0-or-later |
|---|---|
| 2 | /* |
| 3 | * DEC I/O ASIC's counter clocksource |
| 4 | * |
| 5 | * Copyright (C) 2008 Yoichi Yuasa <yuasa@linux-mips.org> |
| 6 | */ |
| 7 | #include <linux/clocksource.h> |
| 8 | #include <linux/sched_clock.h> |
| 9 | #include <linux/init.h> |
| 10 | |
| 11 | #include <asm/ds1287.h> |
| 12 | #include <asm/time.h> |
| 13 | #include <asm/dec/ioasic.h> |
| 14 | #include <asm/dec/ioasic_addrs.h> |
| 15 | |
| 16 | static u64 dec_ioasic_hpt_read(struct clocksource *cs) |
| 17 | { |
| 18 | return ioasic_read(IO_REG_FCTR); |
| 19 | } |
| 20 | |
| 21 | static struct clocksource clocksource_dec = { |
| 22 | .name = "dec-ioasic", |
| 23 | .read = dec_ioasic_hpt_read, |
| 24 | .mask = CLOCKSOURCE_MASK(32), |
| 25 | .flags = CLOCK_SOURCE_IS_CONTINUOUS, |
| 26 | }; |
| 27 | |
| 28 | static u64 notrace dec_ioasic_read_sched_clock(void) |
| 29 | { |
| 30 | return ioasic_read(IO_REG_FCTR); |
| 31 | } |
| 32 | |
| 33 | int __init dec_ioasic_clocksource_init(void) |
| 34 | { |
| 35 | unsigned int freq; |
| 36 | u32 start, end; |
| 37 | int i = HZ / 8; |
| 38 | |
| 39 | ds1287_timer_state(); |
| 40 | while (!ds1287_timer_state()) |
| 41 | ; |
| 42 | |
| 43 | start = dec_ioasic_hpt_read(cs: &clocksource_dec); |
| 44 | |
| 45 | while (i--) |
| 46 | while (!ds1287_timer_state()) |
| 47 | ; |
| 48 | |
| 49 | end = dec_ioasic_hpt_read(cs: &clocksource_dec); |
| 50 | |
| 51 | freq = (end - start) * 8; |
| 52 | |
| 53 | /* An early revision of the I/O ASIC didn't have the counter. */ |
| 54 | if (!freq) |
| 55 | return -ENXIO; |
| 56 | |
| 57 | printk(KERN_INFO "I/O ASIC clock frequency %dHz\n", freq); |
| 58 | |
| 59 | clocksource_dec.rating = 200 + freq / 10000000; |
| 60 | clocksource_register_hz(cs: &clocksource_dec, hz: freq); |
| 61 | |
| 62 | sched_clock_register(read: dec_ioasic_read_sched_clock, bits: 32, rate: freq); |
| 63 | |
| 64 | return 0; |
| 65 | } |
| 66 |