diff options
Diffstat (limited to 'drivers/clocksource/efi.c')
-rw-r--r-- | drivers/clocksource/efi.c | 110 |
1 files changed, 110 insertions, 0 deletions
diff --git a/drivers/clocksource/efi.c b/drivers/clocksource/efi.c new file mode 100644 index 0000000000..89906c452e --- /dev/null +++ b/drivers/clocksource/efi.c @@ -0,0 +1,110 @@ +/* + * 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(); + 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); |