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/*
* Copyright (c) 2025 Ian Marco Moffett and L5 engineers
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of the project nor the names of its
* contributors may be used to endorse or promote products derived from
* this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/
/*
* Description: IA-PC HPET timer driver
* Author: Ian Marco Moffett
*/
#include <sys/types.h>
#include <sys/errno.h>
#include <sys/param.h>
#include <sys/syslog.h>
#include <os/mmio.h>
#include <os/clkdev.h>
#include <acpi/acpi.h>
#include <acpi/tables.h>
#include <machine/hpet.h>
#define FSEC_PER_SECOND 1000000000000000ULL
#define USEC_PER_SECOND 1000000ULL
#define HPET_REG_CAPS 0x00
#define HPET_GENERAL_CONFIG 0x10
#define HPET_REG_MAIN_COUNTER 0xF0
#define CAP_REV_ID(caps) (caps & 0xFF)
#define CAP_NUM_TIM(caps) (caps >> 8) & 0x1F
#define CAP_CLK_PERIOD(caps) (caps >> 32)
static struct clkdev clkdev;
static void *hpet_base = NULL;
/*
* Read from HPET register space.
*
* @reg: Register to read from.
*/
static inline uint64_t
hpet_read(uint32_t reg)
{
void *addr;
addr = PTR_OFFSET(hpet_base, reg);
return mmio_read64(addr);
}
/*
* Write to HPET register space.
*
* @reg: Register to write to.
* @val: Value to write.
*/
static inline void
hpet_write(uint32_t reg, uint64_t val)
{
void *addr;
addr = PTR_OFFSET(hpet_base, reg);
mmio_write64(addr, val);
}
/*
* Sleep for 'n' amount of 'units'
*
* @n: Number of 'units' to sleep
* @units: Units per 'n'
*
* Returns zero on success, otherwise a less than zero
* value.
*/
static int
hpet_sleep(uint64_t n, uint64_t units)
{
uint64_t caps;
uint32_t period;
uint64_t counter_val;
volatile size_t ticks;
caps = hpet_read(HPET_REG_CAPS);
period = CAP_CLK_PERIOD(caps);
counter_val = hpet_read(HPET_REG_MAIN_COUNTER);
ticks = counter_val + (n * (units / period));
while (hpet_read(HPET_REG_MAIN_COUNTER) < ticks) {
__ASMV("rep; nop");
}
return 0;
}
static int
hpet_msleep(size_t ms)
{
return hpet_sleep(ms, 1000000000000);
}
/*
* Get time since init in usec
*/
static size_t
hpet_time_usec(void)
{
uint64_t period, freq, caps;
uint64_t counter;
caps = hpet_read(HPET_REG_CAPS);
period = CAP_CLK_PERIOD(caps);
freq = FSEC_PER_SECOND / period;
counter = hpet_read(HPET_REG_MAIN_COUNTER);
return (counter * USEC_PER_SECOND) / freq;
}
/*
* Initialize the HPET
*/
int
hpet_init(void)
{
struct acpi_gas *gas;
struct acpi_hpet *hpet;
uint64_t caps;
hpet = acpi_query("HPET");
if (hpet == NULL) {
return -ENODEV;
}
gas = &hpet->gas;
hpet_base = (void *)gas->address;
caps = hpet_read(HPET_REG_CAPS);
if (CAP_REV_ID(caps) == 0) {
printf("hpet_init: bad revision HPET ID\n");
return -1;
}
/*
* The spec states this counter clk period must
* be <= 0x05F5E100. So we'll consider it as bogus
* if it exceeds this value
*/
if (CAP_CLK_PERIOD(caps) > 0x05F5E100) {
printf("hpet_init: bad COUNTER_CLK_PERIOD\n");
return -1;
}
/*
* Clear the counter and enable the HPET via
* the ENABLE_CNF bit in general_config
*/
hpet_write(HPET_REG_MAIN_COUNTER, 0);
hpet_write(HPET_GENERAL_CONFIG, 1);
printf("hpet: HPET initialized and enabled\n");
/* Initialize as clock device */
clkdev.name = "IA-PC HPET";
clkdev.attr = CLKDEV_MSLEEP | CLKDEV_GET_USEC;
clkdev.msleep = hpet_msleep;
clkdev.get_time_usec = hpet_time_usec;
if (clkdev_register(&clkdev) < 0) {
printf("hpet_init: could not register clock device\n");
return -1;
}
return 0;
}
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