IDEDiskDevice: Implement basic DMA writes.

This could share more code with reads, and generally be better. But it works
and it's considerably faster than PIO, so let's use it. :^)

Kernel/Devices/IDEDiskDevice.cpp

@@ -120,6 +120,8 @@ bool IDEDiskDevice::read_block(unsigned index, byte* out) const
 
 bool IDEDiskDevice::write_blocks(unsigned index, word count, const byte* data)
 {
+ if (m_bus_master_base && m_dma_enabled.resource())
+ return write_sectors_with_dma(index, count, data);
  for (unsigned i = 0; i < count; ++i) {
  if (!write_sectors(index + i, 1, data + i * 512))
  return false;
@@ -374,6 +376,79 @@ bool IDEDiskDevice::read_sectors(dword start_sector, word count, byte* outbuf)
  return true;
 }
 
+bool IDEDiskDevice::write_sectors_with_dma(dword lba, word count, const byte* inbuf)
+{
+ LOCKER(m_lock);
+#ifdef DISK_DEBUG
+ dbgprintf("%s(%u): IDEDiskDevice::write_sectors_with_dma (%u x%u) <- %p\n",
+ current->process().name().characters(),
+ current->pid(), lba, count, inbuf);
+#endif
+
+ disable_irq();
+
+ m_prdt.offset = m_dma_buffer_page->paddr();
+ m_prdt.size = 512 * count;
+
+ memcpy(m_dma_buffer_page->paddr().as_ptr(), inbuf, 512 * count);
+
+ ASSERT(m_prdt.size <= PAGE_SIZE);
+
+ // Stop bus master
+ IO::out8(m_bus_master_base, 0);
+
+ // Write the PRDT location
+ IO::out32(m_bus_master_base + 4, (dword)&m_prdt);
+
+ // Turn on "Interrupt" and "Error" flag. The error flag should be cleared by hardware.
+ IO::out8(m_bus_master_base + 2, IO::in8(m_bus_master_base + 2) | 0x6);
+
+ m_interrupted = false;
+ enable_irq();
+
+ while (IO::in8(m_io_base + ATA_REG_STATUS) & ATA_SR_BSY);
+
+ bool is_slave = false;
+
+ IO::out8(m_io_base + ATA_REG_CONTROL, 0);
+ IO::out8(m_io_base + ATA_REG_HDDEVSEL, 0xe0 | (is_slave << 4));
+ wait_400ns(m_io_base);
+
+ IO::out8(m_io_base + ATA_REG_FEATURES, 0);
+
+ IO::out8(m_io_base + ATA_REG_SECCOUNT0, 0);
+ IO::out8(m_io_base + ATA_REG_LBA0, 0);
+ IO::out8(m_io_base + ATA_REG_LBA1, 0);
+ IO::out8(m_io_base + ATA_REG_LBA2, 0);
+
+ IO::out8(m_io_base + ATA_REG_SECCOUNT0, count);
+ IO::out8(m_io_base + ATA_REG_LBA0, (lba & 0x000000ff) >> 0);
+ IO::out8(m_io_base + ATA_REG_LBA1, (lba & 0x0000ff00) >> 8);
+ IO::out8(m_io_base + ATA_REG_LBA2, (lba & 0x00ff0000) >> 16);
+
+ for (;;) {
+ auto status = IO::in8(m_io_base + ATA_REG_STATUS);
+ if (!(status & ATA_SR_BSY) && (status & ATA_SR_DRDY))
+ break;
+ }
+
+ IO::out8(m_io_base + ATA_REG_COMMAND, ATA_CMD_WRITE_DMA_EXT);
+ wait_400ns(m_io_base);
+
+ // Start bus master
+ IO::out8(m_bus_master_base, 0x1);
+
+ wait_for_irq();
+ disable_irq();
+
+ if (m_device_error)
+ return false;
+
+ // I read somewhere that this may trigger a cache flush so let's do it.
+ IO::out8(m_bus_master_base + 2, IO::in8(m_bus_master_base + 2) | 0x6);
+ return true;
+}
+
 bool IDEDiskDevice::write_sectors(dword start_sector, word count, const byte* data)
 {
  ASSERT(count <= 256);

Kernel/Devices/IDEDiskDevice.h

@@ -39,9 +39,10 @@ class IDEDiskDevice final : public IRQHandler, public DiskDevice {
 
  void initialize();
  bool wait_for_irq();
- bool read_sectors_with_dma(dword sector, word count, byte*);
- bool read_sectors(dword start_sector, word count, byte* buffer);
- bool write_sectors(dword start_sector, word count, const byte* data);
+ bool read_sectors_with_dma(dword lba, word count, byte*);
+ bool write_sectors_with_dma(dword lba, word count, const byte*);
+ bool read_sectors(dword lba, word count, byte* buffer);
+ bool write_sectors(dword lba, word count, const byte* data);
 
  Lock m_lock { "IDEDiskDevice" };
  word m_cylinders { 0 };