1 files changed, 141 insertions, 0 deletions
diff --git a/kernel/src/acpi/acpi.c b/kernel/src/acpi/acpi.c
new file mode 100644
index 0000000..ef1fb76
--- /dev/null
+++ b/kernel/src/acpi/acpi.c
@@ -0,0 +1,141 @@
+#include <panic.h>
+#include <string.h>
+#include <stdbool.h>
+#include <stddef.h>
+#include <stdint.h>
+#include <sys.h>
+
+#include "acpi.h"
+#include "boot/tag.h"
+#include "print.h"
+
+static struct RootSystemDescriptionTable *rsdt;
+static struct FixedACPIDescriptionTable *fadt;
+
+static uint16_t SLP_TYPa;
+static uint16_t SLP_TYPb;
+static uint16_t SLP_EN;
+static uint16_t SCI_EN;
+
+static bool is_init = false;
+
+bool checksum(uint8_t *data, size_t len) {
+    unsigned char sum = 0;
+    for (size_t i = 0; i < len; i++)
+        sum += data[i];
+    return sum == 0;
+}
+
+static void *find_fadt(void) {
+    int entries = (rsdt->header.length - sizeof(rsdt->header)) / 4;
+ 
+    for (int i = 0; i < entries; i++) {
+        uintptr_t sdt_ptr = rsdt->sdt_table[i];
+        struct SystemDescriptionTableHeader *h = (void*) sdt_ptr;
+        if (!strncmp(h->signature, "FACP", 4))
+            return (void *) h;
+    }
+ 
+    return NULL;
+}
+
+static int read_s5_addr(void) {
+    uintptr_t ptr = fadt->dsdt;
+    char *s5_addr = (void*) (ptr + 36);
+    
+    int dsdt_len = *((int*) (ptr+1)) - 36;
+    while (0 < dsdt_len--) {
+       if ( memcmp(s5_addr, "_S5_", 4) == 0)
+          break;
+       s5_addr++;
+    }
+
+    if (dsdt_len > 0) {
+        // check for valid AML structure
+        if ( ( *(s5_addr-1) == 0x08 || ( *(s5_addr-2) == 0x08 && *(s5_addr-1) == '\\') ) && *(s5_addr+4) == 0x12 ) {
+            s5_addr += 5;
+            s5_addr += ((*s5_addr &0xC0)>>6) +2;   // calculate PkgLength size
+
+            if (*s5_addr == 0x0A)
+               s5_addr++;   // skip byteprefix
+            SLP_TYPa = *(s5_addr)<<10;
+            s5_addr++;
+
+            if (*s5_addr == 0x0A)
+               s5_addr++;   // skip byteprefix
+            SLP_TYPb = *(s5_addr)<<10;
+
+            SLP_EN = 1<<13;
+            SCI_EN = 1;
+
+        } else {
+            errork("\\_S5 parse error.");
+            return 1;
+        }
+    } else {
+        errork("\\_S5 not present.");
+        return 1;
+    }
+    return 0;
+}
+
+void acpi_init(void) {
+
+    is_init = false;
+
+    debugk("Loading ACPI");
+
+    struct BootTag *tag;
+    if(!get_boot_tag(ID_RSDP, &tag)) {
+        errork("Could not find RSDP");
+        return;
+    }
+
+    debugk("Loading RSDT");
+
+    struct RootSystemDescriptionPointer *rsdp = tag->data.rsdp;
+    if (!checksum((uint8_t*) rsdp, sizeof(struct RootSystemDescriptionPointer))) {
+        errork("RSDP checksum failed to validate");
+        return;
+    }
+
+    uintptr_t rsdt_ptr = rsdp->rsdt_address;
+    rsdt = (void *) rsdt_ptr;
+    if (!checksum((uint8_t*) &rsdt->header, rsdt->header.length)) {
+        errork("RSDT checksum failed to validate");
+        return;
+    }
+
+    debugk("Loading FADT");
+
+    fadt = find_fadt();
+    if (fadt == NULL) {
+        errork("Could not find FADT");
+        return;
+    }
+
+    if (!checksum((uint8_t*) &fadt->header, fadt->header.length)) {
+        errork("FADT checksum failed to validate");
+        return;
+    }
+
+    debugk("Reading \\_S5 Addr");
+
+    if (read_s5_addr()) {
+        return;
+    }
+
+    outb(fadt->smi_command_port,fadt->acpi_enable);
+
+    succek("ACPI has been loaded");
+    is_init = true;
+}
+
+void acpi_poweroff(void) {
+    if (is_init) {
+        outw((unsigned int) fadt->pm1_a_control_block, SLP_TYPb | SLP_EN);
+        panic("failed to shutdown");
+    } else {
+        errork("Cannot shutdown, ACPI not loaded");
+    }
+}