From 7a7d87b02aed5c5df944667fe68d47f345378954 Mon Sep 17 00:00:00 2001
From: Malo Lecomte <malo.lecomte@epita.fr>
Date: Wed, 28 Jul 2021 23:46:18 +0200
Subject: [PATCH] feat(atapi): add send_packet and read_block implementations

---
 k/atapi.c | 69 +++++++++++++++++++++++++++++++++++++++++++++++++++----
 1 file changed, 64 insertions(+), 5 deletions(-)

diff --git a/k/atapi.c b/k/atapi.c
index d03e709..b2a6916 100644
--- a/k/atapi.c
+++ b/k/atapi.c
@@ -6,11 +6,7 @@
 
 static struct atapi_drive drives[4] = { 0 };
 
-static void select_drive(uint16_t bus, uint8_t slave)
-{
-    outb(ATA_REG_DRIVE(bus), slave);
-}
-
+/* wait functions */
 static void busy_wait(uint16_t drive)
 {
     int res = 0;
@@ -24,6 +20,19 @@ static void wait_device_selection(uint16_t drive)
         inb(drive);
 }
 
+static void wait_packet_request(uint16_t drive)
+{
+    int res = 0;
+    while (res & BSY && !(res & DRQ))
+        res = inb(ATA_REG_STATUS(drive));
+}
+
+/* drive discover functions */
+static void select_drive(uint16_t bus, uint8_t slave)
+{
+    outb(ATA_REG_DRIVE(bus), slave);
+}
+
 static uint8_t is_atapi_drive(uint16_t bus, uint8_t slave)
 {
     static uint8_t atapi_sig[] = { ATAPI_SIG_SC, ATAPI_SIG_LBA_LO,
@@ -89,3 +98,53 @@ void discover_atapi_drive(void)
     wait_device_selection(SECONDARY_REG);
     is_atapi_drive(SECONDARY_REG, ATA_PORT_SLAVE);
 }
+
+/* IO functions */
+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];
+    memcpy(packet, pkt, PACKET_SZ * sizeof(uint8_t));
+
+    // wait for a packet to be requested
+    busy_wait(drive);
+    outb(ATA_REG_FEATURES(drive), 0);
+    outb(ATA_REG_SECTOR_COUNT(drive), 0);
+    outb(ATA_REG_LBA_MI(drive), size);
+    outb(ATA_REG_LBA_HI(drive), size >> 8);
+    outb(ATA_REG_COMMAND(drive), PACKET);
+    wait_packet_request(drive);
+
+    // write SCSI packet
+    for (int i = 0; i < PACKET_SZ / 2; ++i)
+        outw(ATA_REG_DATA(drive), packet[i]);
+    uint8_t read = 0;
+    while (read != PACKET_DATA_TRANSMIT)
+        read = inb(ATA_REG_SECTOR_COUNT(drive));
+
+    return 0;
+}
+
+static char block[CD_BLOCK_SZ];
+
+void read_block(size_t lba, uint16_t drive)
+{
+    struct SCSI_packet pkt = { 0 };
+    pkt.op_code  = READ_12;
+    pkt.lba_lo   = lba & 0xff;
+    pkt.lba_milo = (lba >> 0x8)  & 0xff;
+    pkt.lba_mihi = (lba >> 0x10) & 0xff;
+    pkt.lba_hi   = (lba >> 0x18) & 0xff;
+    pkt.transfer_length_lo = 1;
+
+    send_packet(&pkt, drive, PACKET_SZ);
+
+    // we can now read
+    uint16_t *buf = block;
+    for (int i = 0; i < CD_BLOCK_SZ / 2; ++i)
+        buf[i] = inw(ATA_REG_DATA(drive));
+
+    uint8_t read = 0;
+    while (read != PACKET_COMMAND_COMPLETE)
+        read = inb(ATA_REG_SECTOR_COUNT(drive));
+}