Hi Aleksandar,
On Mon, Oct 30, 2017 at 12:56:36PM +0100, Aleksandar Markovic wrote:
> diff --git a/arch/mips/generic/board-ranchu.c
> b/arch/mips/generic/board-ranchu.c
> new file mode 100644
> index 0000000..0397752
> --- /dev/null
> +++ b/arch/mips/generic/board-ranchu.c
> @@ -0,0 +1,79 @@
> +/*
> + * Support code for virtual Ranchu board for MIPS.
> + *
> + * Author: Miodrag Dinic <miodrag.di...@mips.com>
> + *
> + * This program is free software; you can redistribute it and/or modify it
> + * under the terms of the GNU General Public License as published by the
> + * Free Software Foundation; either version 2 of the License, or (at your
> + * option) any later version.
> + */
> +
> +#include <linux/of_address.h>
> +
> +#include <asm/machine.h>
You should also include asm/mipsregs.h for read_c0_count(), even though it's
presumably being pulled in indirectly as-is.
> +#include <asm/time.h>
> +
> +#define GOLDFISH_TIMER_LOW 0x00
> +#define GOLDFISH_TIMER_HIGH 0x04
> +
> +static __init uint64_t read_rtc_time(void __iomem *base)
> +{
> + u64 time_low;
> + u64 time_high;
> +
> + time_low = readl(base + GOLDFISH_TIMER_LOW);
> + time_high = readl(base + GOLDFISH_TIMER_HIGH);
> +
> + return (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 1 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;
> +
> + count += 5000; /* round */
> + count -= count % 10000;
> +
> + return count;
> +}
Would it be possible to have the emulator write the frequency into the
devicetree, as the frequency of a fixed-clock used as the CPU's clock? If that
were possible then there'd be no need for this board setup code at all. Not a
big deal, but it'd be nice.
> +
> +static const struct of_device_id ranchu_of_match[];
> +
> +MIPS_MACHINE(ranchu) = {
> + .matches = ranchu_of_match,
> + .measure_hpt_freq = ranchu_measure_hpt_freq,
> +};
> +
> +static const struct of_device_id ranchu_of_match[] = {
> + {
> + .compatible = "mti,ranchu",
> + .data = &__mips_mach_ranchu,
> + },
> +};
Could you move ranchu_of_match before the MIPS_MACHINE & drop the forward
declaration? That would feel tidier to me. It could also be marked as
__initdata.
In general though, with those & James' comments addressed, I think this is
looking good.
Thanks,
Paul
