diff options
Diffstat (limited to 'sys/dev/timer')
| -rw-r--r-- | sys/dev/timer/hpet.c | 158 |
1 files changed, 158 insertions, 0 deletions
diff --git a/sys/dev/timer/hpet.c b/sys/dev/timer/hpet.c new file mode 100644 index 0000000..1089096 --- /dev/null +++ b/sys/dev/timer/hpet.c @@ -0,0 +1,158 @@ +/* + * Copyright (c) 2023 Ian Marco Moffett and the VegaOS team. + * 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 VegaOS 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. + */ + +#include <dev/timer/hpet.h> +#include <firmware/acpi/acpi.h> +#include <sys/panic.h> +#include <sys/cdefs.h> +#include <sys/syslog.h> +#include <sys/mmio.h> + +__MODULE_NAME("hpet"); +__KERNEL_META("$Vega$: hpet.c, Ian Marco Moffett, " + "HPET driver"); + +#define HPET_REG_CAPS 0x00 +#define HPET_GENERAL_CONFIG 0x10 +#define HPET_REG_MAIN_COUNTER 0xF0 + +#define CAP_REV_ID(caps) __SHIFTOUT(caps, 0xFF) +#define CAP_NUM_TIM(caps) __SHIFTOUT(caps, 0x1F << 8) +#define CAP_COUNT_SIZE(caps) __SHIFTOUT(caps, __BIT(13)) +#define CAP_VENDOR_ID(caps) __SHIFTOUT(caps, 0xFFFF << 16) +#define CAP_CLK_PERIOD(caps) (caps >> 32) + +/* + * TODO: Use some sort of helper function that + * uses PAUSE or some similar instruction + * for the current architecture. It is + * *not* a good idea to spin for a prolonged + * amount of time without it. For now we'll + * just use PAUSE on x86_64 like this. + */ +#if defined(__x86_64__) +#define spinwait_hint() __ASMV("pause") +#else +#define spinwait_hint() __nothing +#endif /* defined(__x86_64__) */ + +static struct hpet *acpi_hpet = NULL; +static void *hpet_base = NULL; +static bool is_faulty = false; + +/* + * Read from HPET register space. + * + * @reg: Register to read from. + */ +static inline uint64_t +hpet_read(uint32_t reg) +{ + void *addr; + + addr = (void *)((uintptr_t)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 = (void *)((uintptr_t)hpet_base + reg); + mmio_write64(addr, val); +} + +void +hpet_msleep(size_t ms) +{ + 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 + (ms * (1000000000000 / period)); + + while (hpet_read(HPET_REG_MAIN_COUNTER) < ticks) { + spinwait_hint(); + } +} + +int +hpet_init(void) +{ + struct acpi_gas *gas; + uint64_t caps; + + acpi_hpet = acpi_query("HPET"); + if (acpi_hpet == NULL) + return 1; /* Not found */ + + gas = &acpi_hpet->gas; + hpet_base = (void *)gas->address; + caps = hpet_read(HPET_REG_CAPS); + + /* Ensure caps aren't bogus */ + if (CAP_REV_ID(caps) == 0) { + KERR("Found bogus revision, assuming faulty\n"); + is_faulty = true; + return 1; + } + if (CAP_CLK_PERIOD(caps) > 0x05F5E100) { + /* + * The spec states this counter clk period + * must be <= 0x05F5E100. So we'll consider it + * as bogus if it exceeds this value + */ + KERR("Found bogus COUNTER_CLK_PERIOD, assuming faulty\n"); + KINFO("HPET REV - 0x%x\n", CAP_REV_ID(caps)); + KINFO("COUNTER_CLK_PERIOD - 0x%x\n", CAP_CLK_PERIOD(caps)); + is_faulty = true; + return 1; + } + + KINFO("HPET integrity verified\n"); + + hpet_write(HPET_REG_MAIN_COUNTER, 0); + hpet_write(HPET_GENERAL_CONFIG, 1); + + /* Not faulty */ + is_faulty = false; + return 0; +} |