cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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board-ranchu.c (2014B)

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