12874c5fdSThomas Gleixner // SPDX-License-Identifier: GPL-2.0-or-later
2f2d0b0d5SMiodrag Dinic /*
3f2d0b0d5SMiodrag Dinic * Support code for virtual Ranchu board for MIPS.
4f2d0b0d5SMiodrag Dinic *
5f2d0b0d5SMiodrag Dinic * Author: Miodrag Dinic <miodrag.dinic@mips.com>
6f2d0b0d5SMiodrag Dinic */
7f2d0b0d5SMiodrag Dinic
8f2d0b0d5SMiodrag Dinic #include <linux/of_address.h>
9f2d0b0d5SMiodrag Dinic #include <linux/types.h>
10f2d0b0d5SMiodrag Dinic
11f2d0b0d5SMiodrag Dinic #include <asm/machine.h>
12f2d0b0d5SMiodrag Dinic #include <asm/mipsregs.h>
13f2d0b0d5SMiodrag Dinic #include <asm/time.h>
14f2d0b0d5SMiodrag Dinic
15f2d0b0d5SMiodrag Dinic #define GOLDFISH_TIMER_LOW 0x00
16f2d0b0d5SMiodrag Dinic #define GOLDFISH_TIMER_HIGH 0x04
17f2d0b0d5SMiodrag Dinic
read_rtc_time(void __iomem * base)18f2d0b0d5SMiodrag Dinic static __init u64 read_rtc_time(void __iomem *base)
19f2d0b0d5SMiodrag Dinic {
20f2d0b0d5SMiodrag Dinic u32 time_low;
21f2d0b0d5SMiodrag Dinic u32 time_high;
22f2d0b0d5SMiodrag Dinic
23f2d0b0d5SMiodrag Dinic /*
24f2d0b0d5SMiodrag Dinic * Reading the low address latches the high value
25f2d0b0d5SMiodrag Dinic * as well so there is no fear that we may read
26f2d0b0d5SMiodrag Dinic * inaccurate high value.
27f2d0b0d5SMiodrag Dinic */
28f2d0b0d5SMiodrag Dinic time_low = readl(base + GOLDFISH_TIMER_LOW);
29f2d0b0d5SMiodrag Dinic time_high = readl(base + GOLDFISH_TIMER_HIGH);
30f2d0b0d5SMiodrag Dinic
31f2d0b0d5SMiodrag Dinic return ((u64)time_high << 32) | time_low;
32f2d0b0d5SMiodrag Dinic }
33f2d0b0d5SMiodrag Dinic
ranchu_measure_hpt_freq(void)34f2d0b0d5SMiodrag Dinic static __init unsigned int ranchu_measure_hpt_freq(void)
35f2d0b0d5SMiodrag Dinic {
36f2d0b0d5SMiodrag Dinic u64 rtc_start, rtc_current, rtc_delta;
37f2d0b0d5SMiodrag Dinic unsigned int start, count;
38f2d0b0d5SMiodrag Dinic struct device_node *np;
39f2d0b0d5SMiodrag Dinic void __iomem *rtc_base;
40f2d0b0d5SMiodrag Dinic
41f2d0b0d5SMiodrag Dinic np = of_find_compatible_node(NULL, NULL, "google,goldfish-rtc");
42f2d0b0d5SMiodrag Dinic if (!np)
43f2d0b0d5SMiodrag Dinic panic("%s(): Failed to find 'google,goldfish-rtc' dt node!",
44f2d0b0d5SMiodrag Dinic __func__);
45f2d0b0d5SMiodrag Dinic
46f2d0b0d5SMiodrag Dinic rtc_base = of_iomap(np, 0);
47*4becf641SLiang He of_node_put(np);
48f2d0b0d5SMiodrag Dinic if (!rtc_base)
49f2d0b0d5SMiodrag Dinic panic("%s(): Failed to ioremap Goldfish RTC base!", __func__);
50f2d0b0d5SMiodrag Dinic
51f2d0b0d5SMiodrag Dinic /*
52f2d0b0d5SMiodrag Dinic * Poll the nanosecond resolution RTC for one
53f2d0b0d5SMiodrag Dinic * second to calibrate the CPU frequency.
54f2d0b0d5SMiodrag Dinic */
55f2d0b0d5SMiodrag Dinic rtc_start = read_rtc_time(rtc_base);
56f2d0b0d5SMiodrag Dinic start = read_c0_count();
57f2d0b0d5SMiodrag Dinic
58f2d0b0d5SMiodrag Dinic do {
59f2d0b0d5SMiodrag Dinic rtc_current = read_rtc_time(rtc_base);
60f2d0b0d5SMiodrag Dinic rtc_delta = rtc_current - rtc_start;
61f2d0b0d5SMiodrag Dinic } while (rtc_delta < NSEC_PER_SEC);
62f2d0b0d5SMiodrag Dinic
63f2d0b0d5SMiodrag Dinic count = read_c0_count() - start;
64f2d0b0d5SMiodrag Dinic
65f2d0b0d5SMiodrag Dinic /*
66f2d0b0d5SMiodrag Dinic * Make sure the frequency will be a round number.
67f2d0b0d5SMiodrag Dinic * Without this correction, the returned value may vary
68f2d0b0d5SMiodrag Dinic * between subsequent emulation executions.
69f2d0b0d5SMiodrag Dinic *
70f2d0b0d5SMiodrag Dinic * TODO: Set this value using device tree.
71f2d0b0d5SMiodrag Dinic */
72f2d0b0d5SMiodrag Dinic count += 5000;
73f2d0b0d5SMiodrag Dinic count -= count % 10000;
74f2d0b0d5SMiodrag Dinic
75f2d0b0d5SMiodrag Dinic iounmap(rtc_base);
76f2d0b0d5SMiodrag Dinic
77f2d0b0d5SMiodrag Dinic return count;
78f2d0b0d5SMiodrag Dinic }
79f2d0b0d5SMiodrag Dinic
80f2d0b0d5SMiodrag Dinic static const struct of_device_id ranchu_of_match[] __initconst = {
81f2d0b0d5SMiodrag Dinic {
82f2d0b0d5SMiodrag Dinic .compatible = "mti,ranchu",
83f2d0b0d5SMiodrag Dinic },
84e17ae5cdSJames Hogan {}
85f2d0b0d5SMiodrag Dinic };
86f2d0b0d5SMiodrag Dinic
87f2d0b0d5SMiodrag Dinic MIPS_MACHINE(ranchu) = {
88f2d0b0d5SMiodrag Dinic .matches = ranchu_of_match,
89f2d0b0d5SMiodrag Dinic .measure_hpt_freq = ranchu_measure_hpt_freq,
90f2d0b0d5SMiodrag Dinic };
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