3 files changed, 74 insertions, 2 deletions
diff --git a/src/kernel/arch/i386/ata.c b/src/kernel/arch/i386/ata.c
new file mode 100644
index 0000000..996fa3a
--- /dev/null
+++ b/src/kernel/arch/i386/ata.c
@@ -0,0 +1,65 @@
+#include <kernel/arch/i386/ata.h>
+#include <kernel/arch/i386/port_io.h>
+#include <stdbool.h>
+
+#include <kernel/arch/io.h>
+
+enum {
+	LBAlo  = 3,
+	LBAmid = 4,
+	LBAhi  = 5,
+	DRV    = 6,
+	CMD    = 7,
+	STATUS = 7,
+}; // offsets
+
+// get I/O port base for drive
+static uint16_t ata_iobase(int drive) {
+	bool secondary = drive&2;
+	return secondary ? 0x170 : 0x1F0;
+}
+
+static void ata_driveselect(int drive, int block) {
+	uint8_t v = 0xE0;
+	if (drive&1) // slave?
+		v |= 0x10; // set drive number bit
+	// TODO account for block
+	port_outb(ata_iobase(drive) + DRV, v);
+}
+
+static bool ata_identify(int drive) {
+	uint16_t iobase = ata_iobase(drive);
+	uint8_t v;
+
+	ata_driveselect(drive, 0);
+	for (int i = 2; i < 6; i++)
+		port_outb(iobase + i, 0);
+	port_outb(iobase + CMD, 0xEC); // IDENTIFY
+
+	v = port_inb(iobase + STATUS);
+	if (v == 0) return false; // nonexistent drive
+	while (port_inb(iobase + STATUS) & 0x80);
+
+	/* check for uncomformant devices, quit early */
+	if (port_inb(iobase + LBAmid) || port_inb(iobase + LBAhi)) {
+		// TODO atapi
+		return true;
+	}
+	/* pool until bit 3 (DRQ) or 0 (ERR) is set */
+	while (!((v = port_inb(iobase + STATUS) & 0x9)));
+	if (v & 1) return false; /* ERR was set, bail */
+
+	// now I can read 512 bytes of data, TODO
+	return true;
+}
+
+void ata_init(void) {
+	tty_const("\n");
+	for (int i = 0; i < 4; i++) {
+		tty_const("probing drive ");
+		_tty_var(i);
+		if (ata_identify(i))
+			tty_const(" - exists");
+		tty_const("\n");
+	}
+}
diff --git a/src/kernel/arch/i386/ata.h b/src/kernel/arch/i386/ata.h
new file mode 100644
index 0000000..9137cdb
--- /dev/null
+++ b/src/kernel/arch/i386/ata.h
@@ -0,0 +1,4 @@
+#pragma once
+#include <stdint.h>
+
+void ata_init(void);
diff --git a/src/kernel/arch/i386/boot.c b/src/kernel/arch/i386/boot.c
index bd2a00b..94e9e2f 100644
--- a/src/kernel/arch/i386/boot.c
+++ b/src/kernel/arch/i386/boot.c
@@ -1,4 +1,5 @@
 #include <kernel/arch/generic.h>
+#include <kernel/arch/i386/ata.h>
 #include <kernel/arch/i386/boot.h>
 #include <kernel/arch/i386/gdt.h>
 #include <kernel/arch/i386/interrupts/idt.h>
@@ -15,7 +16,9 @@ void kmain_early(struct multiboot_info *multiboot) {
 	gdt_init();
 	tty_const("idt...");
 	idt_init();
-	
+	tty_const("ata...");
+	ata_init();
+
 	{ // find the init module
 		struct multiboot_mod *module = &multiboot->mods[0];
 		if (multiboot->mods_count < 1) {
@@ -25,6 +28,6 @@ void kmain_early(struct multiboot_info *multiboot) {
 		info.init.at   = module->start;
 		info.init.size = module->end - module->start;
 	}
-	
+
 	kmain(info);
 }