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/*
* Copyright (C) 2017 Jean-Christophe PLAGNIOL-VILLARD <plagnio@jcrosoft.com>
*
* Under GPL v2
*/
#include <common.h>
#include <init.h>
#include <driver.h>
#include <clock.h>
#include <efi.h>
#include <efi/efi.h>
#include <efi/efi-device.h>
#include <linux/err.h>
static uint64_t ticks = 1;
static void *efi_cs_evt;
static uint64_t efi_cs_read(void)
{
return ticks;
}
static void efi_cs_inc(void *event, void *ctx)
{
ticks++;
}
/* count ticks during a 1dms */
static uint64_t ticks_freq(void)
{
uint64_t ticks_start, ticks_end;
ticks_start = ticks;
BS->stall(1000);
ticks_end = ticks;
return (ticks_end - ticks_start) * 1000;
}
/* count ticks during a 20ms delay as on qemu x86_64 the max is 100Hz */
static uint64_t ticks_freq_x86(void)
{
uint64_t ticks_start, ticks_end;
ticks_start = ticks;
BS->stall(20 * 1000);
ticks_end = ticks;
return (ticks_end - ticks_start) * 50;
}
static int efi_cs_init(struct clocksource *cs)
{
efi_status_t efiret;
uint64_t freq;
efiret = BS->create_event(EFI_EVT_TIMER | EFI_EVT_NOTIFY_SIGNAL,
EFI_TPL_CALLBACK, efi_cs_inc, NULL, &efi_cs_evt);
if (EFI_ERROR(efiret))
return -efi_errno(efiret);
efiret = BS->set_timer(efi_cs_evt, EFI_TIMER_PERIODIC, 10);
if (EFI_ERROR(efiret)) {
BS->close_event(efi_cs_evt);
return -efi_errno(efiret);
}
freq = 1000 * 1000;
if (ticks_freq() < 800 * 1000) {
uint64_t nb_100ns;
freq = ticks_freq_x86();
if (freq == 0) {
BS->close_event(efi_cs_evt);
return -ENODEV;
}
nb_100ns = 10 * 1000 * 1000 / freq;
pr_warn("EFI Event timer too slow freq = %llu Hz\n", freq);
efiret = BS->set_timer(efi_cs_evt, EFI_TIMER_PERIODIC, nb_100ns);
if (EFI_ERROR(efiret)) {
BS->close_event(efi_cs_evt);
return -efi_errno(efiret);
}
}
cs->mult = clocksource_hz2mult(freq, cs->shift);
return 0;
}
static struct clocksource efi_cs = {
.read = efi_cs_read,
.mask = CLOCKSOURCE_MASK(64),
.shift = 0,
.init = efi_cs_init,
};
static int efi_cs_probe(struct device_d *dev)
{
return init_clock(&efi_cs);
}
static struct driver_d efi_cs_driver = {
.name = "efi-cs",
.probe = efi_cs_probe,
};
static int efi_cs_initcall(void)
{
return platform_driver_register(&efi_cs_driver);
}
/* for efi the time must be init at core initcall level */
core_initcall(efi_cs_initcall);
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