From 4544f9039a513e02d233209ba025d16ebbdf5273 Mon Sep 17 00:00:00 2001
From: Jeremy Soller <jackpot51@gmail.com>
Date: Sat, 8 Oct 2016 20:36:21 -0600
Subject: [PATCH] Enable bus mastering

---
 drivers/pcid/src/main.rs    |  6 ++++++
 drivers/pcid/src/pci/mod.rs | 11 +++++++++++
 2 files changed, 17 insertions(+)

diff --git a/drivers/pcid/src/main.rs b/drivers/pcid/src/main.rs
index a34ff17..108e830 100644
--- a/drivers/pcid/src/main.rs
+++ b/drivers/pcid/src/main.rs
@@ -108,6 +108,12 @@ fn main() {
                             }
 
                             if let Some(ref args) = driver.command {
+                                // Enable bus mastering
+                                unsafe {
+                                    let cmd = pci.read(bus.num, dev.num, func.num, 0x04);
+                                    pci.write(bus.num, dev.num, func.num, 0x04, cmd | 4);
+                                }
+
                                 let mut args = args.iter();
                                 if let Some(program) = args.next() {
                                     let mut command = Command::new(program);
diff --git a/drivers/pcid/src/pci/mod.rs b/drivers/pcid/src/pci/mod.rs
index 0d760ef..d2a8e89 100644
--- a/drivers/pcid/src/pci/mod.rs
+++ b/drivers/pcid/src/pci/mod.rs
@@ -34,6 +34,17 @@ impl Pci {
             : "={eax}"(value) : "{eax}"(address) : "dx" : "intel", "volatile");
         value
     }
+
+    #[cfg(any(target_arch = "x86", target_arch = "x86_64"))]
+    pub unsafe fn write(&self, bus: u8, dev: u8, func: u8, offset: u8, value: u32) {
+        let address = 0x80000000 | ((bus as u32) << 16) | ((dev as u32) << 11) | ((func as u32) << 8) | ((offset as u32) & 0xFC);
+        asm!("mov dx, 0xCF8
+            out dx, eax"
+            : : "{eax}"(address) : "dx" : "intel", "volatile");
+        asm!("mov dx, 0xCFC
+            out dx, eax"
+            : : "{eax}"(value) : "dx" : "intel", "volatile");
+    }
 }
 
 pub struct PciIter<'pci> {