1 files changed, 82 insertions, 0 deletions
diff --git a/drivers/staging/greybus/timesync_platform.c b/drivers/staging/greybus/timesync_platform.c
new file mode 100644
index 000000000000..113f3d6c4b3a
--- /dev/null
+++ b/drivers/staging/greybus/timesync_platform.c
@@ -0,0 +1,82 @@
+/*
+ * TimeSync API driver.
+ *
+ * Copyright 2016 Google Inc.
+ * Copyright 2016 Linaro Ltd.
+ *
+ * Released under the GPLv2 only.
+ *
+ * This code reads directly from an ARMv7 memory-mapped timer that lives in
+ * MMIO space. Since this counter lives inside of MMIO space its shared between
+ * cores and that means we don't have to worry about issues like TSC on x86
+ * where each time-stamp-counter (TSC) is local to a particular core.
+ *
+ * Register-level access code is based on
+ * drivers/clocksource/arm_arch_timer.c
+ */
+#include <linux/cpufreq.h>
+#include <linux/of_platform.h>
+
+#include "greybus.h"
+#include "arche_platform.h"
+
+#define DEFAULT_FRAMETIME_CLOCK_HZ 19200000
+
+static u32 gb_timesync_clock_frequency;
+int (*arche_platform_change_state_cb)(enum arche_platform_state state,
+				      struct gb_timesync_svc *pdata);
+EXPORT_SYMBOL_GPL(arche_platform_change_state_cb);
+
+u64 gb_timesync_platform_get_counter(void)
+{
+	return (u64)get_cycles();
+}
+
+u32 gb_timesync_platform_get_clock_rate(void)
+{
+	if (unlikely(!gb_timesync_clock_frequency)) {
+		gb_timesync_clock_frequency = cpufreq_get(0);
+		if (!gb_timesync_clock_frequency)
+			gb_timesync_clock_frequency = DEFAULT_FRAMETIME_CLOCK_HZ;
+	}
+
+	return gb_timesync_clock_frequency;
+}
+
+int gb_timesync_platform_lock_bus(struct gb_timesync_svc *pdata)
+{
+	return arche_platform_change_state_cb(ARCHE_PLATFORM_STATE_TIME_SYNC,
+					      pdata);
+}
+
+void gb_timesync_platform_unlock_bus(void)
+{
+	arche_platform_change_state_cb(ARCHE_PLATFORM_STATE_ACTIVE, NULL);
+}
+
+static const struct of_device_id arch_timer_of_match[] = {
+	{ .compatible   = "google,greybus-frame-time-counter", },
+	{},
+};
+
+int __init gb_timesync_platform_init(void)
+{
+	struct device_node *np;
+
+	np = of_find_matching_node(NULL, arch_timer_of_match);
+	if (!np) {
+		/* Tolerate not finding to allow BBB etc to continue */
+		pr_warn("Unable to find a compatible ARMv7 timer\n");
+		return 0;
+	}
+
+	if (of_property_read_u32(np, "clock-frequency",
+				 &gb_timesync_clock_frequency)) {
+		pr_err("Unable to find timer clock-frequency\n");
+		return -ENODEV;
+	}
+
+	return 0;
+}
+
+void gb_timesync_platform_exit(void) {}