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