From ca3826bfe5ee15b1fcec41c261fcd7b6e638236b Mon Sep 17 00:00:00 2001
From: TheOddGarlic <umutinanerdogan@pm.me>
Date: Fri, 12 Aug 2022 12:19:08 +0300
Subject: [PATCH] IDE device discovery

---
 ableos/src/devices/pci/piix.rs | 67 ++++++++++++++++++++++++++++++++--
 1 file changed, 63 insertions(+), 4 deletions(-)

diff --git a/ableos/src/devices/pci/piix.rs b/ableos/src/devices/pci/piix.rs
index 606c58d6..693fbcc8 100644
--- a/ableos/src/devices/pci/piix.rs
+++ b/ableos/src/devices/pci/piix.rs
@@ -6,6 +6,7 @@
 
 use core::num::TryFromIntError;
 
+use x86_64::instructions::interrupts;
 use x86_64::structures::paging::{FrameAllocator, FrameDeallocator};
 // FIXME: platform agnostic paging stuff
 use x86_64::structures::paging::{mapper::MapToError, Mapper, Page, PhysFrame, Size4KiB};
@@ -34,6 +35,9 @@ const PRIMARY_COMMAND: u16 = 0x01F0;
 /// Secondary command block offset
 const SECONDARY_COMMAND: u16 = 0x0170;
 
+/// Data register offset
+const DATA_OFFSET: u16 = 0;
+
 /// Drive/Head register offset
 const DRIVE_HEAD_OFFSET: u16 = 6;
 
@@ -80,6 +84,7 @@ impl Piix {
 
                 unsafe {
                     select_drive(drive, channel);
+                    // FIXME: clear sector count and lba0, lba1, lba2 registers
                     let status = ata_send_command(CMD_IDENTIFY, channel);
                     if status == 0 {
                         continue; // If status = 0, no device
@@ -105,6 +110,49 @@ impl Piix {
                             break;
                         }
                     }
+
+                    // Read identification space of device
+                    let addr = if channel.secondary() {
+                        SECONDARY_COMMAND
+                    } else {
+                        PRIMARY_COMMAND
+                    } + DATA_OFFSET;
+                    let mut buffer = [0_u8; 512];
+                    read_dword_buffer(addr, buffer.as_mut_ptr() as *mut _, 128);
+                    // for (i, byte) in buffer.iter().enumerate() {
+                    //     if byte.is_ascii() {
+                    //         trace!("byte {i}: {byte:b}, ascii: {}", *byte as char);
+                    //     } else {
+                    //         trace!("byte {i}: {byte:b}");
+                    //     }
+                    // }
+
+                    if buffer[99] & 1 != 1 {
+                        // FIXME: PIO mode support
+                        error!("IDE drive {channel:?}/{drive:?} does not support DMA");
+                        continue;
+                    }
+
+                    if (buffer[167] >> 2) & 1 != 1 {
+                        // FIXME: 24-bit LBA and CHS support
+                        error!("IDE drive {channel:?}/{drive:?} does not support 48-bit LBA");
+                    }
+
+                    let size = buffer[200] as u64
+                        | (buffer[201] as u64) << 8
+                        | (buffer[202] as u64) << 16
+                        | (buffer[203] as u64) << 24
+                        | (buffer[204] as u64) << 32
+                        | (buffer[205] as u64) << 40
+                        | (buffer[206] as u64) << 48
+                        | (buffer[207] as u64) << 54;
+                    trace!("IDE drive {channel:?}/{drive:?} has {size} sectors");
+
+                    ide_devices.push(IdeDevice {
+                        channel,
+                        drive,
+                        size,
+                    });
                 }
             }
         }
@@ -332,13 +380,24 @@ unsafe fn ata_delay(channel: Channel) {
     }
 }
 
+unsafe fn read_dword_buffer(port: u16, buffer: *mut u32, mut count: u32) {
+    // FIXME: this assumes x86-64
+    interrupts::without_interrupts(|| {
+        asm!("
+        cld
+        repne
+        insd",
+            in("di") buffer,
+            in("dx") port,
+            inout("cx") count,
+        )
+    });
+}
+
 struct IdeDevice {
     pub channel: Channel,
     pub drive: Drive,
-    pub signature: u16,
-    pub capabilities: u16,
-    pub command_sets: u32,
-    pub size: u64,
+    pub size: u64, // in sectors
 }
 
 #[derive(Copy, Clone, Debug)]