// SPDX-License-Identifier: GPL-2.0-or-later /* * Support code for virtual Ranchu board for MIPS. * * Author: Miodrag Dinic <miodrag.dinic@mips.com> */ #include <linux/of_address.h> #include <linux/types.h> #include <asm/machine.h> #include <asm/mipsregs.h> #include <asm/time.h> #define GOLDFISH_TIMER_LOW 0x00 #define GOLDFISH_TIMER_HIGH 0x04 static __init u64 read_rtc_time(void __iomem *base) { u32 time_low; u32 time_high; /* * Reading the low address latches the high value * as well so there is no fear that we may read * inaccurate high value. */ time_low = readl(base + GOLDFISH_TIMER_LOW); time_high = readl(base + GOLDFISH_TIMER_HIGH); return ((u64)time_high << 32) | time_low; } static __init unsigned int ranchu_measure_hpt_freq(void) { u64 rtc_start, rtc_current, rtc_delta; unsigned int start, count; struct device_node *np; void __iomem *rtc_base; np = of_find_compatible_node(NULL, NULL, "google,goldfish-rtc"); if (!np) panic("%s(): Failed to find 'google,goldfish-rtc' dt node!", __func__); rtc_base = of_iomap(np, 0); if (!rtc_base) panic("%s(): Failed to ioremap Goldfish RTC base!", __func__); /* * Poll the nanosecond resolution RTC for one * second to calibrate the CPU frequency. */ rtc_start = read_rtc_time(rtc_base); start = read_c0_count(); do { rtc_current = read_rtc_time(rtc_base); rtc_delta = rtc_current - rtc_start; } while (rtc_delta < NSEC_PER_SEC); count = read_c0_count() - start; /* * Make sure the frequency will be a round number. * Without this correction, the returned value may vary * between subsequent emulation executions. * * TODO: Set this value using device tree. */ count += 5000; count -= count % 10000; iounmap(rtc_base); return count; } static const struct of_device_id ranchu_of_match[] __initconst = { { .compatible = "mti,ranchu", }, {} }; MIPS_MACHINE(ranchu) = { .matches = ranchu_of_match, .measure_hpt_freq = ranchu_measure_hpt_freq, };