kernel: dev: Add HPET driver

Signed-off-by: sigsegv7 <ian@vegaa.systems>

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;
+}