1  /* SPDX-License-Identifier: GPL-2.0-only */
 2  
 3  #include <stdint.h>
 4  
 5  #include <device/pci_ops.h>
 6  #include <device/pci_def.h>
 7  
 8  #include "gm45.h"
 9  
10  void init_iommu(void)
11  {
12  	/* FIXME: proper test? */
13  	int me_active = pci_read_config8(PCI_DEV(0, 3, 0), PCI_CLASS_REVISION) != 0xff;
14  	int stepping = pci_read_config8(PCI_DEV(0, 0, 0), PCI_CLASS_REVISION);
15  
16  	mchbar_write32(0x28, IOMMU_BASE1 | 1); /* HDA @ 0:1b.0 */
17  	if (stepping != STEPPING_B2) {
18  		/* The official workaround is to run SMM every 64ms.
19  		   The only winning move is not to play. */
20  		mchbar_write32(0x18, IOMMU_BASE2 | 1); /* IGD @ 0:2.0-1 */
21  	} else {
22  		/* write-once, so lock it down */
23  		mchbar_write32(0x18, 0); /* disable IOMMU for IGD @ 0:2.0-1 */
24  	}
25  	if (me_active) {
26  		mchbar_write32(0x10, IOMMU_BASE3 | 1); /* ME  @ 0:3.0-3 */
27  	} else {
28  		mchbar_write32(0x10, 0); /* disable IOMMU for ME */
29  	}
30  	mchbar_write32(0x20, IOMMU_BASE4 | 1); /* all other DMA sources */
31  
32  	if (stepping == STEPPING_B3) {
33  		mchbar_setbits8(0xffc, 1 << 4);
34  		const pci_devfn_t peg = PCI_DEV(0, 1, 0);
35  
36  		/* FIXME: proper test? */
37  		if (pci_read_config8(peg, PCI_CLASS_REVISION) != 0xff)
38  			pci_or_config32(peg, 0xfc, 1 << 15);
39  	}
40  
41  	/* final */
42  	mchbar_setbits8(0x94, 1 << 3);
43  }