From 9618d0d55a1fc3dcc933997194b8c491b88d8e56 Mon Sep 17 00:00:00 2001
From: Malo Lecomte <malo.lecomte@epita.fr>
Date: Thu, 29 Jul 2021 01:45:52 +0200
Subject: [PATCH] feat(atapi): discover and store only one drive

---
 k/atapi.c | 49 +++++++++++++++++++++++--------------------------
 1 file changed, 23 insertions(+), 26 deletions(-)

diff --git a/k/atapi.c b/k/atapi.c
index b2a6916..aed6531 100644
--- a/k/atapi.c
+++ b/k/atapi.c
@@ -1,10 +1,11 @@
 #include <k/atapi.h>
 #include <string.h>
+#include <stdio.h>
 
 #include "atapi.h"
 #include "io.h"
 
-static struct atapi_drive drives[4] = { 0 };
+static struct atapi_drive a_drive = { 0 };
 
 /* wait functions */
 static void busy_wait(uint16_t drive)
@@ -16,7 +17,7 @@ static void busy_wait(uint16_t drive)
 
 static void wait_device_selection(uint16_t drive)
 {
-    for (int i = 0; i < 4; ++i)
+    for (int i = 0; i < 400; ++i)
         inb(drive);
 }
 
@@ -47,20 +48,7 @@ static uint8_t is_atapi_drive(uint16_t bus, uint8_t slave)
     if (!memcmp(sig, atapi_sig, 4))
     {
         struct atapi_drive d = { bus, slave };
-        if (bus == PRIMARY_REG)
-        {
-            if (slave)
-                drives[1] = d;
-            else
-                drives[0] = d;
-        }
-        else
-        {
-            if (slave)
-                drives[3] = d;
-            else
-                drives[2] = d;
-        }
+        memcpy(&a_drive, &d, sizeof(struct atapi_drive));
 
         return 1;
     }
@@ -77,12 +65,14 @@ void discover_atapi_drive(void)
     // master_port
     select_drive(PRIMARY_REG, ATA_PORT_MASTER);
     wait_device_selection(PRIMARY_REG);
-    is_atapi_drive(PRIMARY_REG, ATA_PORT_MASTER);
+    if (is_atapi_drive(PRIMARY_REG, ATA_PORT_MASTER))
+        return;
 
     // slave port
     select_drive(PRIMARY_REG, ATA_PORT_SLAVE);
     wait_device_selection(PRIMARY_REG);
-    is_atapi_drive(PRIMARY_REG, ATA_PORT_SLAVE);
+    if (is_atapi_drive(PRIMARY_REG, ATA_PORT_SLAVE))
+        return;
 
     /* secondary_reg */
     outb(SECONDARY_DCR, SRST);
@@ -91,16 +81,18 @@ void discover_atapi_drive(void)
     // master_port
     select_drive(SECONDARY_REG, ATA_PORT_MASTER);
     wait_device_selection(SECONDARY_REG);
-    is_atapi_drive(SECONDARY_REG, ATA_PORT_MASTER);
+    if (is_atapi_drive(SECONDARY_REG, ATA_PORT_MASTER))
+        return;
 
     // slave port
     select_drive(SECONDARY_REG, ATA_PORT_SLAVE);
     wait_device_selection(SECONDARY_REG);
-    is_atapi_drive(SECONDARY_REG, ATA_PORT_SLAVE);
+    if (is_atapi_drive(SECONDARY_REG, ATA_PORT_SLAVE))
+        return;
 }
 
 /* IO functions */
-int send_packet(struct SCSI_packet *pkt, uint16_t drive, uint16_t size)
+static int send_packet(struct SCSI_packet *pkt, uint16_t drive, uint16_t size)
 {
     // cpy SCSI_packet into uint16_t array
     uint16_t packet[PACKET_SZ / 2];
@@ -127,8 +119,11 @@ int send_packet(struct SCSI_packet *pkt, uint16_t drive, uint16_t size)
 
 static char block[CD_BLOCK_SZ];
 
-void read_block(size_t lba, uint16_t drive)
+void *read_block(size_t lba)
 {
+    select_drive(a_drive.reg, a_drive.drive);
+    wait_device_selection(a_drive.reg);
+
     struct SCSI_packet pkt = { 0 };
     pkt.op_code  = READ_12;
     pkt.lba_lo   = lba & 0xff;
@@ -137,14 +132,16 @@ void read_block(size_t lba, uint16_t drive)
     pkt.lba_hi   = (lba >> 0x18) & 0xff;
     pkt.transfer_length_lo = 1;
 
-    send_packet(&pkt, drive, PACKET_SZ);
+    send_packet(&pkt, a_drive.reg, PACKET_SZ);
 
     // we can now read
-    uint16_t *buf = block;
+    uint16_t *buf = (uint16_t *)block;
     for (int i = 0; i < CD_BLOCK_SZ / 2; ++i)
-        buf[i] = inw(ATA_REG_DATA(drive));
+        buf[i] = inw(ATA_REG_DATA(a_drive.reg));
 
     uint8_t read = 0;
     while (read != PACKET_COMMAND_COMPLETE)
-        read = inb(ATA_REG_SECTOR_COUNT(drive));
+        read = inb(ATA_REG_SECTOR_COUNT(a_drive.reg));
+
+    return block;
 }