kern: pci: Add bus framework and PCI BAR mapper

Signed-off-by: Ian Moffett <ian@osmora.org>

2 files changed, 114 insertions, 0 deletions

diff --git a/src/sys/arch/amd64/io/pci/bar.c b/src/sys/arch/amd64/io/pci/bar.c
index 265d873..1a7e766 100644
--- a/src/sys/arch/amd64/io/pci/bar.c
+++ b/src/sys/arch/amd64/io/pci/bar.c
@@ -65,3 +65,33 @@ pci_bar_size(struct pci_device *dev, uint8_t bar)
     pci_writel(dev, barreg, reg_tmp);
     return reg;
 }
+
+/*
+ * Map a BAR into host memory
+ */
+int
+pci_map_bar(struct pci_device *dev, uint8_t bar, struct bus_space *bs_res)
+{
+    size_t len;
+    bus_addr_t pa;
+    uint8_t barreg = pci_get_barreg(bar);
+    uintptr_t tmp;
+
+    if (dev == NULL || bs_res == NULL) {
+        return -EINVAL;
+    }
+
+    if (barreg == 0) {
+        return -EINVAL;
+    }
+
+    /* This must be MMIO */
+    tmp = pci_readl(dev, barreg);
+    if (PCI_BAR_IO(tmp)) {
+        return -EINVAL;
+    }
+
+    pa = tmp & ~0x7;
+    len = pci_bar_size(dev, bar);
+    return bus_space_map(bs_res, pa, len);
+}
diff --git a/src/sys/arch/amd64/os/os_bus.c b/src/sys/arch/amd64/os/os_bus.c
new file mode 100644
index 0000000..96f841d
--- /dev/null
+++ b/src/sys/arch/amd64/os/os_bus.c
@@ -0,0 +1,84 @@
+/*
+ * Copyright (c) 2025 Ian Marco Moffett and L5 engineers
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice,
+ *    this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. Neither the name of the project nor the names of its
+ *    contributors may be used to endorse or promote products derived from
+ *    this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <sys/types.h>
+#include <sys/cdefs.h>
+#include <sys/errno.h>
+#include <sys/syslog.h>
+#include <sys/param.h>
+#include <os/bus.h>
+#include <vm/physseg.h>
+#include <vm/mmu.h>
+#include <vm/vm.h>
+#include <vm/map.h>
+
+/*
+ * Map a BAR address into host memory
+ */
+int
+bus_space_map(struct bus_space *bp, bus_addr_t pa, size_t len)
+{
+    static size_t PSIZE = DEFAULT_PAGESIZE;
+    struct vm_vas vas;
+    struct mmu_map spec;
+    vaddr_t va;
+    int error;
+
+    if (bp == NULL || pa == 0) {
+        return -EINVAL;
+    }
+
+    /* Get the current VAS */
+    error = mmu_this_vas(&vas);
+    if (error < 0) {
+        printf("bus_space_map: could not read VAS\n");
+        return error;
+    }
+
+    spec.pa = pa;
+    spec.va = va;
+    error = vm_map(&vas, &spec, len, PROT_READ | PROT_WRITE);
+    if (error < 0) {
+        printf("bus_space_map: could not map base\n");
+        return error;
+    }
+
+    /* Mark uncachable and global */
+    pmap_set_cache(
+        &vas, pa,
+        MMU_CACHE_UC |
+        MMU_CACHE_GL
+    );
+
+    /* Identity mapped */
+    bp->va_base = (void *)pa;
+    bp->length = len;
+    bp->type = BUS_PCI_PCI;
+    return 0;
+}