pci: add device enumeration code

Add probe_pci, probe_pci_bus, probe_pci_dev and init_pci functions. init_pci is called from kernel_start to setup the PCI subsystem. In turn, init_pci calls probe_pci, which initializes the host bridge and then recursively enumerates the rest of the PCI devices on the system by calling probe_pci_bus/probe_pci_dev. Each device's basic config space is stored in the pcidev_t structure, along with a pointer to the device's parent bridge and a list_head_t node. When a device is found, it is added to the global pci_list structure for later reference. Signed-off-by: Connor Davis <[email protected]>
KernelTestFramework · Jan 18, 2022 · 18f5903 · 18f5903
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diff --git a/common/pci.c b/common/pci.c
@@ -0,0 +1,163 @@
+/*
+ * Copyright © 2022 Amazon.com, Inc. or its affiliates.
+ * 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.
+ *
+ * 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 <list.h>
+#include <mm/slab.h>
+#include <pci.h>
+#include <pci_cfg.h>
+#include <string.h>
+
+static list_head_t pci_list = LIST_INIT(pci_list);
+
+static inline uint8_t pci_dev_hdr_type(pcidev_t *dev) { return dev->hdr & PCI_HDR_TYPE; }
+
+static inline bool pci_dev_is_multifunc(pcidev_t *dev) {
+    return ((dev->hdr & PCI_HDR_MULTIFUNC) != 0);
+}
+
+static pcidev_t *probe_pci_dev(uint8_t bus, uint8_t dev, uint8_t func,
+                               uint32_t device_vendor) {
+    uint32_t cfg_val;
+    pcidev_t *new_dev = kzalloc(sizeof(*new_dev));
+
+    if (NULL == new_dev)
+        return NULL;
+
+    new_dev->segment = 0;
+    new_dev->bus = bus;
+    new_dev->dev = dev;
+    new_dev->func = func;
+
+    new_dev->vendor_id = PCI_VENDOR(device_vendor);
+    new_dev->device_id = PCI_DEVICE(device_vendor);
+
+    cfg_val = pci_cfg_read(bus, dev, func, PCI_REG_COMMAND);
+    new_dev->command = PCI_COMMAND(cfg_val);
+    new_dev->status = PCI_STATUS(cfg_val);
+
+    cfg_val = pci_cfg_read(bus, dev, func, PCI_REG_CLASS);
+    new_dev->class = PCI_CLASS(cfg_val);
+    new_dev->subclass = PCI_SUBCLASS(cfg_val);
+
+    cfg_val = pci_cfg_read(bus, dev, func, PCI_REG_HDR);
+    new_dev->hdr = PCI_HDR(cfg_val);
+
+    if (new_dev->status & PCI_STATUS_CAP_LIST)
+        new_dev->cap_ptr = pci_cfg_read8(bus, dev, func, PCI_REG_CAP_PTR);
+
+    return new_dev;
+}
+
+static void probe_pci_bus(uint8_t bus, uint8_t start_dev, pcidev_t *bridge) {
+    for (uint8_t dev = start_dev; dev < PCI_NR_DEV; dev++) {
+        for (uint8_t func = 0; func < PCI_NR_FUNC; func++) {
+            pcidev_t *new_dev;
+            uint32_t cfg_val;
+
+            cfg_val = pci_cfg_read(bus, dev, func, PCI_REG_VENDOR);
+            if (!PCI_DEV_EXISTS(cfg_val)) {
+                continue;
+            }
+
+            new_dev = probe_pci_dev(bus, dev, func, cfg_val);
+            BUG_ON(!new_dev);
+
+            new_dev->bridge = bridge;
+            snprintf(&new_dev->bdf_str[0], sizeof(new_dev->bdf_str), "%02x:%1x.%1x", bus,
+                     dev, func);
+
+            list_add_tail(&new_dev->list, &pci_list);
+
+            if (pci_dev_hdr_type(new_dev) == PCI_HDR_TYPE_PCI_BRIDGE) {
+                uint8_t secondary, subordinate;
+
+                cfg_val = pci_cfg_read(bus, dev, func, PCI_REG_BUS);
+                secondary = PCI_SEC_BUS(cfg_val);
+                subordinate = PCI_SUB_BUS(cfg_val);
+
+                for (uint8_t b = secondary; b <= subordinate; b++) {
+                    probe_pci_bus(b, 0, new_dev);
+                }
+            }
+
+            if (!pci_dev_is_multifunc(new_dev))
+                break;
+        }
+    }
+}
+
+static void probe_pci(void) {
+    pcidev_t *host_bridge;
+    uint32_t cfg_val;
+    uint32_t class_reg;
+    const uint8_t bus = 0;
+    const uint8_t dev = 0;
+    const uint8_t func = 0;
+    const uint32_t vendor_reg = pci_cfg_read(bus, dev, func, PCI_REG_VENDOR);
+
+    if (!PCI_DEV_EXISTS(vendor_reg)) {
+        printk("pci: non-existent host bridge @ 00.0.0\n");
+        return;
+    }
+
+    class_reg = pci_cfg_read(bus, dev, func, PCI_REG_CLASS);
+    if (PCI_CLASS(class_reg) != PCI_CLASS_BRIDGE &&
+        PCI_SUBCLASS(class_reg) != PCI_SUBCLASS_HOST_BRIDGE) {
+        printk("pci: expected host bridge class code @ 00.0.0\n");
+        return;
+    }
+
+    /* Found the host bridge, initialize it */
+    host_bridge = kzalloc(sizeof(*host_bridge));
+    BUG_ON(!host_bridge);
+
+    host_bridge->segment = 0;
+    host_bridge->vendor_id = PCI_VENDOR(vendor_reg);
+    host_bridge->device_id = PCI_DEVICE(vendor_reg);
+
+    cfg_val = pci_cfg_read(bus, dev, func, PCI_REG_COMMAND);
+    host_bridge->command = PCI_COMMAND(cfg_val);
+    host_bridge->status = PCI_STATUS(cfg_val);
+
+    host_bridge->class = PCI_CLASS_BRIDGE;
+    host_bridge->subclass = PCI_SUBCLASS_HOST_BRIDGE;
+    host_bridge->bridge = NULL;
+
+    strncpy(&host_bridge->bdf_str[0], "00:0.0", sizeof(host_bridge->bdf_str));
+    list_add_tail(&host_bridge->list, &pci_list);
+
+    /* Probe the rest of bus 0 */
+    probe_pci_bus(0, 1, host_bridge);
+}
+
+void init_pci(void) {
+    pcidev_t *dev;
+
+    printk("Initializing PCI\n");
+    probe_pci();
+
+    list_for_each_entry (dev, &pci_list, list) {
+        printk("pci: found device at %s\n", &dev->bdf_str[0]);
+    }
+}
diff --git a/common/setup.c b/common/setup.c
@@ -34,6 +34,7 @@
 #include <multiboot.h>
 #include <page.h>
 #include <pagetable.h>
+#include <pci.h>
 #include <percpu.h>
 #include <real_mode.h>
 #include <sched.h>
@@ -290,6 +291,8 @@ void __noreturn __text_init kernel_start(uint32_t multiboot_magic,
 
     init_ioapic();
 
+    init_pci();
+
     /* Initialize console input */
     uart_input_init(get_bsp_cpu_id());
 

diff --git a/include/pci.h b/include/pci.h
@@ -0,0 +1,106 @@
+/*
+ * Copyright © 2022 Amazon.com, Inc. or its affiliates.
+ * 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.
+ *
+ * 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 KTF_PCI_H
+#define KTF_PCI_H
+
+#include <list.h>
+
+#define PCI_NR_BUS  256
+#define PCI_NR_DEV  32
+#define PCI_NR_FUNC 8
+
+#define PCI_VENDOR_MASK    0x0000FFFF
+#define PCI_VENDOR_INVALID 0xFFFF
+
+#define PCI_DEVICE_MASK  0xFFFF0000
+#define PCI_DEVICE_SHIFT 16
+
+#define PCI_COMMAND_MASK 0x0000FFFF
+
+#define PCI_STATUS_MASK     0xFFFF0000
+#define PCI_STATUS_SHIFT    16
+#define PCI_STATUS_CAP_LIST (1U << 4)
+
+#define PCI_CLASS_MASK   0xFF000000
+#define PCI_CLASS_SHIFT  24
+#define PCI_CLASS_BRIDGE 0x06
+
+#define PCI_SUBCLASS_MASK        0x00FF0000
+#define PCI_SUBCLASS_SHIFT       16
+#define PCI_SUBCLASS_HOST_BRIDGE 0x0
+
+#define PCI_HDR_MASK            0x00FF0000
+#define PCI_HDR_SHIFT           16
+#define PCI_HDR_TYPE            0x7F
+#define PCI_HDR_TYPE_NORMAL     0x00
+#define PCI_HDR_TYPE_PCI_BRIDGE 0x01
+#define PCI_HDR_MULTIFUNC       0x80
+
+#define PCI_SEC_BUS_MASK  0x0000FF00
+#define PCI_SEC_BUS_SHIFT 8
+#define PCI_SUB_BUS_MASK  0x00FF0000
+#define PCI_SUB_BUS_SHIFT 16
+
+#define PCI_REG_VENDOR  0x0
+#define PCI_REG_COMMAND 0x1
+#define PCI_REG_CLASS   0x2
+#define PCI_REG_HDR     0x3
+#define PCI_REG_BUS     0x6
+#define PCI_REG_CAP_PTR 0xD
+
+#define PCI_VENDOR(cfg_reg0)   (cfg_reg0 & PCI_VENDOR_MASK)
+#define PCI_DEVICE(cfg_reg0)   ((cfg_reg0 & PCI_DEVICE_MASK) >> PCI_DEVICE_SHIFT)
+#define PCI_COMMAND(cfg_reg1)  (cfg_reg1 & PCI_COMMAND_MASK)
+#define PCI_STATUS(cfg_reg1)   ((cfg_reg1 & PCI_STATUS_MASK) >> PCI_STATUS_SHIFT)
+#define PCI_CLASS(cfg_reg2)    ((cfg_reg2 & PCI_CLASS_MASK) >> PCI_CLASS_SHIFT)
+#define PCI_SUBCLASS(cfg_reg2) ((cfg_reg2 & PCI_SUBCLASS_MASK) >> PCI_SUBCLASS_SHIFT)
+#define PCI_HDR(cfg_reg3)      ((cfg_reg3 & PCI_HDR_MASK) >> PCI_HDR_SHIFT)
+#define PCI_SEC_BUS(cfg_reg6)  ((cfg_reg6 & PCI_SEC_BUS_MASK) >> PCI_SEC_BUS_SHIFT)
+#define PCI_SUB_BUS(cfg_reg6)  ((cfg_reg6 & PCI_SUB_BUS_MASK) >> PCI_SUB_BUS_SHIFT)
+
+#define PCI_DEV_EXISTS(cfg_reg0) (PCI_VENDOR(cfg_reg0) != PCI_VENDOR_INVALID)
+
+struct pcidev {
+    list_head_t list;
+    uint32_t segment : 16;
+    uint32_t bus : 8;
+    uint32_t dev : 5;
+    uint32_t func : 3;
+    uint16_t vendor_id;
+    uint16_t device_id;
+    uint16_t command;
+    uint16_t status;
+    uint8_t subclass;
+    uint8_t class;
+    uint8_t hdr;
+    uint8_t cap_ptr;
+    struct pcidev *bridge;
+    char bdf_str[7];
+};
+typedef struct pcidev pcidev_t;
+
+extern void init_pci(void);
+
+#endif /* KTF_PCI_H */