From f5fa3dccc2eda8a7f674bc3677280ff7a8a0186a Mon Sep 17 00:00:00 2001
From: Oliver Miyar Ugarte <olivermiyar10@hotmail.com>
Date: Tue, 3 Mar 2026 11:58:20 -0300
Subject: [PATCH] Add PCI_IOC_MAP_BAR ioctl for userspace BAR mapping

Add struct pciio_bar_map to pciio.h
---
 sys/dev/pci/pci_usrreq.c | 71 ++++++++++++++++++++++++++++++++++++++++
 sys/dev/pci/pciio.h      | 15 +++++++++
 2 files changed, 86 insertions(+)

diff --git a/sys/dev/pci/pci_usrreq.c b/sys/dev/pci/pci_usrreq.c
index 0645fffaf2c9c..e72c8e899c46c 100644
--- a/sys/dev/pci/pci_usrreq.c
+++ b/sys/dev/pci/pci_usrreq.c
@@ -146,6 +146,77 @@ pciioctl(dev_t dev, u_long cmd, void *data, int flag, struct lwp *l)
 			sizeof dnameonbus->name);
 		return 0;
 
+	case PCI_IOC_MAP_BAR:
+	{
+		struct pciio_bar_map *barmap = data;
+		struct pci_child *dev_child = NULL;
+		pcitag_t dev_tag;
+		int reg;
+		pcireg_t bar_value;
+		int idx, dev_idx, range_idx;
+		struct pci_child *c;
+		struct pci_range *r;
+
+		if (barmap->bus > 255 || barmap->function > 7 ||
+		   barmap->barnum > 5 || barmap->device > 31)
+			return EINVAL;
+
+		dev_tag = pci_make_tag(sc->sc_pc, barmap->bus, barmap->device,
+		   barmap->function);
+
+		reg = PCI_BAR(barmap->barnum);
+		bar_value = pci_conf_read(sc->sc_pc, dev_tag, reg);
+
+		for (dev_idx = 0; dev_idx < __arraycount(sc->sc_devices);
+		   dev_idx++) {
+			c = &sc->sc_devices[dev_idx];
+			if (c->c_dev == NULL)
+				continue;
+
+			for (range_idx = 0;
+			   range_idx < __arraycount(c->c_range);
+			   range_idx++) {
+				r = &c->c_range[range_idx];
+				if (r->r_size == 0)
+					break;
+
+				if ((r->r_offset & ~0x0F) ==
+				   (bar_value & ~0x0F)) {
+					dev_child = c;
+					break;
+				}
+			}
+			if (dev_child != NULL)
+				break;
+		}
+
+		if (dev_child == NULL) {
+			barmap->offset = bar_value & ~0x0F;
+			barmap->size = 4096;
+			return 0;
+		}
+
+		for (idx = 0; idx < __arraycount(dev_child->c_range); idx++) {
+			if (dev_child->c_range[idx].r_size == 0)
+				break;
+
+			if ((dev_child->c_range[idx].r_offset & ~0x0F) ==
+			   (bar_value & ~0x0F)) {
+				barmap->offset = dev_child->c_range[idx].r_offset;
+				barmap->size = dev_child->c_range[idx].r_size;
+				break;
+			}
+		}
+
+		if (barmap->offset == 0 && barmap->size == 0) {
+			barmap->offset = bar_value & ~0x0F;
+			barmap->size = dev_child->c_range[0].r_size != 0 ?
+			   dev_child->c_range[0].r_size : 4096;
+		}
+
+		return 0;
+	}
+
 	default:
 		return ENOTTY;
 	}
diff --git a/sys/dev/pci/pciio.h b/sys/dev/pci/pciio.h
index 8af353ca7bd2b..dfe0191a1d8e6 100644
--- a/sys/dev/pci/pciio.h
+++ b/sys/dev/pci/pciio.h
@@ -116,5 +116,20 @@ struct pciio_drvnameonbus {
 };
 #define	PCI_IOC_DRVNAMEONBUS	_IOWR('P', 5, struct pciio_drvnameonbus)
 
+/*
+ * pciio_bar_map:
+ *
+ *	PCI BAR mapping for userspace access.
+ */
+struct pciio_bar_map {
+        int     bus;			/* bus number */
+        int     device;			/* device number  */
+        int     function;		/* function number */
+        int     barnum;			/* BAR number */
+        off_t   offset;			/* offset for mmap */
+        size_t  size;			/* size of BAR */
+};
+
+#define PCI_IOC_MAP_BAR _IOWR('P', 6, struct pciio_bar_map) 
 
 #endif /* _DEV_PCI_PCIIO_H_ */