kern: pci: Add bus framework and PCI BAR mapper

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

4 files changed, 201 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;
+}
diff --git a/src/sys/include/io/pci/bar.h b/src/sys/include/io/pci/bar.h
index 6bb4367..14164ef 100644
--- a/src/sys/include/io/pci/bar.h
+++ b/src/sys/include/io/pci/bar.h
@@ -32,6 +32,7 @@
 
 #include <sys/types.h>
 #include <sys/cdefs.h>
+#include <os/bus.h>
 #include <io/pci/pci.h>
 #include <io/pci/cam.h>
 
@@ -68,4 +69,17 @@ pci_get_barreg(uint8_t bar)
  */
 ssize_t pci_bar_size(struct pci_device *dev, uint8_t bar);
 
+/*
+ * Map a BAR into host address space for the current
+ * process.
+ *
+ * @dev: Device of BAR to map
+ * @bar: BAR number of BAR to map
+ * @bs_res: Result is written here
+ *
+ * Returns zero on success, otherwise a less than
+ * zero value to indicate failure.
+ */
+int pci_map_bar(struct pci_device *dev, uint8_t bar, struct bus_space *bs_res);
+
 #endif  /* !_PCI_BAR_H_ */
diff --git a/src/sys/include/os/bus.h b/src/sys/include/os/bus.h
new file mode 100644
index 0000000..86b1a75
--- /dev/null
+++ b/src/sys/include/os/bus.h
@@ -0,0 +1,73 @@
+/*
+ * 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.
+ */
+
+#ifndef _OS_BUS_H_
+#define _OS_BUS_H_
+
+#include <sys/types.h>
+
+typedef enum {
+    BUS_PCI_NONE,
+    BUS_PCI_PCI,
+} bus_type_t;
+
+/*
+ * Represents a physical or virtual MMIO address that
+ * allows tranmission and reception on the bus.
+ */
+typedef uintptr_t bus_addr_t;
+
+/*
+ * Represents a bus space that can be used with certain
+ * bus interfaces
+ *
+ * @va_base: Virtual address base
+ * @length: Length at buffer
+ * @type: Type of the space space (see BUS_*)
+ */
+struct bus_space {
+    void *va_base;
+    size_t length;
+    bus_type_t type;
+};
+
+/*
+ * Initialize a bus space descriptor and map a physical
+ * bus address.
+ *
+ * @bp: Bus space descriptor to use
+ * @pa: Physical bus address to map.
+ * @len: Length of mapping to use
+ *
+ * Returns zero on success, otherwise a less than zero
+ * value.
+ */
+int bus_space_map(struct bus_space *bp, bus_addr_t pa, size_t len);
+
+#endif  /* !_OS_BUS_H_ */