kern/amd64: io: Add initial PCI CAM driver

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

6 files changed, 299 insertions, 0 deletions

diff --git a/src/sys/arch/amd64/boot/boot_chip.c b/src/sys/arch/amd64/boot/boot_chip.c
index 76753d5..18ab2df 100644
--- a/src/sys/arch/amd64/boot/boot_chip.c
+++ b/src/sys/arch/amd64/boot/boot_chip.c
@@ -36,6 +36,7 @@
 #include <machine/ioapic.h>
 #include <machine/tss.h>
 #include <machine/gdt.h>
+#include <io/pci/pci.h>
 #include <stdbool.h>
 
 static void
@@ -52,6 +53,7 @@ chipset_init(void)
 
     uart_init();
     i8259_disable();
+    pci_init_bus();
 }
 
 /*
diff --git a/src/sys/arch/amd64/io/pci/pci_cam.c b/src/sys/arch/amd64/io/pci/pci_cam.c
new file mode 100644
index 0000000..3fdefd4
--- /dev/null
+++ b/src/sys/arch/amd64/io/pci/pci_cam.c
@@ -0,0 +1,118 @@
+/*
+ * 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.
+ */
+
+/*
+ * Description: PCI(e) CAM driver
+ * Author: Ian Marco Moffett
+ */
+
+#include <sys/errno.h>
+#include <sys/param.h>
+#include <sys/cdefs.h>
+#include <machine/pio.h>
+#include <io/pci/pci.h>
+#include <io/pci/cam.h>
+
+#define PCI_CAM_ADDR    0xCF8
+#define PCI_CAM_DATA    0xCFC
+
+/*
+ * Compute the configuration space address of a specific
+ * device at a specific register offset
+ *
+ * @dev: Device to get address base of
+ * @offset: Desired register offset
+ *
+ * Returns a 32-bit PCI configuration space address
+ */
+static inline uint32_t
+pci_conf_addr(struct pci_device *dev, uint32_t offset)
+{
+    return BIT(31)             |
+           (offset & ~3)       |
+           (dev->func << 8)    |
+           (dev->slot << 11)   |
+           (dev->bus << 16);
+}
+
+/*
+ * Perform a legacy PCI CAM read which interacts
+ * with the lower 256 bytes of the configuration
+ * space. Upon receiving a write to PCI_CAM_ADDR,
+ * the PCI host bridge latches its PCI_CAM_DATA
+ * register at which written data is delegated to
+ * the target device.
+ *
+ * @dp: Device to read from
+ * @off: Register offset to read at
+ *
+ * Returns a 32-bit dword from the device register
+ */
+static pcireg_t
+cam_readl(struct pci_device *dp, uint32_t off)
+{
+    uint32_t conf_addr;
+
+    conf_addr = pci_conf_addr(dp, off);
+    outl(PCI_CAM_ADDR, conf_addr);
+    return inl(PCI_CAM_DATA);
+}
+
+/*
+ * Does the same thing as cam_readl() but for
+ * writing to the configuration space
+ *
+ * @dp: Target device pointer
+ * @off: Register offset to write at
+ * @v: Value to write
+ */
+static void
+cam_writel(struct pci_device *dp, uint32_t off, pcival_t v)
+{
+    uint32_t conf_addr;
+
+    conf_addr = pci_conf_addr(dp, off);
+    outl(PCI_CAM_ADDR, conf_addr);
+    outl(PCI_CAM_DATA, v);
+}
+
+/*
+ * Initialize PCI cam hooks
+ */
+int
+pci_cam_init(struct cam_hook *chp)
+{
+    if (chp == NULL) {
+        return -EINVAL;
+    }
+
+    chp->cam_readl = cam_readl;
+    chp->cam_writel = cam_writel;
+    return 0;
+}
diff --git a/src/sys/include/io/pci/cam.h b/src/sys/include/io/pci/cam.h
new file mode 100644
index 0000000..198e8df
--- /dev/null
+++ b/src/sys/include/io/pci/cam.h
@@ -0,0 +1,63 @@
+/*
+ * 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 _PCI_CAM_H_
+#define _PCI_CAM_H_ 1
+
+#include <sys/types.h>
+#include <io/pci/pci.h>
+
+/*
+ * Configuration Access Mechanism hooks for the
+ * L5 PCI driver.
+ *
+ * Contains read/write hooks:
+ * [
+ *      @dp: Device pointer
+ *      @off: Register offset
+ *      @v[writel]: Value to write
+ * ]
+ */
+struct cam_hook {
+    void(*cam_writel)(struct pci_device *dp, uint32_t off, pcireg_t v);
+    pcireg_t(*cam_readl)(struct pci_device *dp, uint32_t off);
+};
+
+/*
+ * Initialize configuration access mechanism hooks
+ * to be used for PCI device access.
+ *
+ * @chp: (E)CAM hooks
+ *
+ * Returns zero on success, otherwise a less than zero
+ * value to indicate failure.
+ */
+int pci_cam_init(struct cam_hook *chp);
+
+#endif  /* !_PCI_CAM_H_ */
diff --git a/src/sys/include/io/pci/pci.h b/src/sys/include/io/pci/pci.h
new file mode 100644
index 0000000..6306e0c
--- /dev/null
+++ b/src/sys/include/io/pci/pci.h
@@ -0,0 +1,55 @@
+/*
+ * 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 _IO_PCI_H_
+#define _IO_PCI_H_ 1
+
+#include <sys/types.h>
+
+/* PCI register / value types */
+typedef uint32_t pcireg_t;
+typedef uint32_t pcival_t;
+
+/*
+ * Represents a single device attached to the
+ * PCI bus.
+ */
+struct pci_device {
+    uint16_t bus;
+    uint8_t slot;
+    uint8_t func;
+};
+
+/*
+ * Initialize the PCI bus and enumerate attached
+ * devices.
+ */
+void pci_init_bus(void);
+
+#endif  /* !_IO_PCI_H_ */
diff --git a/src/sys/io/pci/pci.c b/src/sys/io/pci/pci.c
new file mode 100644
index 0000000..6109b32
--- /dev/null
+++ b/src/sys/io/pci/pci.c
@@ -0,0 +1,48 @@
+/*
+ * 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/panic.h>
+#include <sys/syslog.h>
+#include <io/pci/pci.h>
+#include <io/pci/cam.h>
+
+static struct cam_hook cam;
+
+void
+pci_init_bus(void)
+{
+    int error;
+
+    error = pci_cam_init(&cam);
+    if (error < 0) {
+        printf("pci_init_bus: pci_cam_init() returned %d\n", error);
+        panic("pci_init_bus: could not init CAM\n");
+    }
+}
diff --git a/src/sys/os/os_stub.c b/src/sys/os/os_stub.c
index a7498e0..1447924 100644
--- a/src/sys/os/os_stub.c
+++ b/src/sys/os/os_stub.c
@@ -28,11 +28,24 @@
  */
 
 #include <sys/cdefs.h>
+#include <sys/errno.h>
 #include <sys/cpuvar.h>
 #include <sys/syslog.h>
+#include <io/pci/cam.h>
 
 __weak void
 bsp_ap_startup(void)
 {
     printf("bsp_ap_startup: unimplemented\n");
 }
+
+/*
+ * PCI cam init hooks stub
+ */
+__weak int
+pci_cam_init(struct cam_hook *chp)
+{
+    (void)chp;
+    printf("pci_cam_init: unimplemented\n");
+    return -ENOTSUP;
+}