1 files changed, 89 insertions, 0 deletions
diff --git a/arch/mips/generic/board-ranchu.c b/arch/mips/generic/board-ranchu.c
new file mode 100644
index 000000000..a89aaad59
--- /dev/null
+++ b/arch/mips/generic/board-ranchu.c
@@ -0,0 +1,89 @@
+// 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,
+};