kern: pci: Implement PCI leaf drivers + AHCI stub

This commit introduces the support for having PCI specific device
drivers while providing a tiny AHCI stub that logs the existence of the
host bus adapter. The PCI bus itself has a driver for enumerating the
devices and associating a specific driver to it, the device drivers
themselve must advertise themselves to the PCI driver.

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

2 files changed, 124 insertions, 2 deletions

diff --git a/src/sys/io/ic/ahci.c b/src/sys/io/ic/ahci.c
new file mode 100644
index 0000000..4515b9d
--- /dev/null
+++ b/src/sys/io/ic/ahci.c
@@ -0,0 +1,81 @@
+/*
+ * 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: AHCI HBA driver
+ * Author: Ian Marco Moffett
+ */
+
+#include <sys/types.h>
+#include <sys/syslog.h>
+#include <sys/cdefs.h>
+#include <io/pci/pci.h>
+#include <os/module.h>
+
+/*
+ * Represents the PCI advocation descriptor for this
+ * device so we can advertise ourselves as its driver.
+ */
+static struct pci_adv driver;
+
+/*
+ * Initialize only the AHCI driver's state rather than
+ * the hardware it covers. This is used so we can advertise
+ * ourself to the PCI driver.
+ */
+static int
+ahci_init(struct module *modp)
+{
+    int error;
+
+    if ((error = pci_advoc(&driver)) < 0) {
+        printf("ahci_init: failed to advocate for HBA\n");
+        return error;
+    }
+    return 0;
+}
+
+/*
+ * Ran when a device is attached, does the actual
+ * hardware initialization.
+ */
+static int
+ahci_attach(struct pci_adv *adv)
+{
+    printf("ahci: detected AHCI controller\n");
+    return 0;
+}
+
+static struct pci_adv driver = {
+    .lookup = PCI_CS_ID(0x1, 0x06),
+    .attach = ahci_attach,
+    .classrev = 1
+};
+
+MODULE_EXPORT("ahci", MODTYPE_PCI, ahci_init);
diff --git a/src/sys/io/pci/pci.c b/src/sys/io/pci/pci.c
index c308c20..af5c113 100644
--- a/src/sys/io/pci/pci.c
+++ b/src/sys/io/pci/pci.c
@@ -40,6 +40,7 @@
 #include <sys/panic.h>
 #include <sys/syslog.h>
 #include <os/kalloc.h>
+#include <os/module.h>
 #include <io/pci/pci.h>
 #include <io/pci/cam.h>
 #include <string.h>
@@ -54,6 +55,7 @@
 #endif  /* __PCI_MAX_BUS */
 
 static TAILQ_HEAD(, pci_device) devlist;
+static TAILQ_HEAD(, pci_adv) advlist;
 static struct cam_hook cam;
 
 /*
@@ -266,10 +268,34 @@ pci_writel(struct pci_device *dp, pcireg_t reg, uint32_t v)
     return cam.cam_writel(dp, reg, v);
 }
 
+/*
+ * Advocate for a specific device
+ */
+int
+pci_advoc(struct pci_adv *advp)
+{
+    struct pci_adv *adv_new;
+
+    if (advp == NULL) {
+        return -EINVAL;
+    }
+
+    adv_new = kalloc(sizeof(*adv_new));
+    if (adv_new == NULL) {
+        printf("pci_advoc: could not alloc adv\n");
+        return -ENOMEM;
+    }
+    *adv_new = *advp;
+    TAILQ_INSERT_TAIL(&advlist, advp, link);
+    return 0;
+}
+
 void
 pci_init_bus(void)
 {
-    struct pci_device *dp;
+    struct pci_adv *advp;
+    struct pci_device dev;
+    lookup_type_t lup;
     int error;
 
     error = pci_cam_init(&cam);
@@ -278,11 +304,26 @@ pci_init_bus(void)
         panic("pci_init_bus: failed to init CAM\n");
     }
 
-    printf("pci: enumerating %d buses\n", PCI_MAX_BUS);
+    /* Initialize device and advocation list */
     TAILQ_INIT(&devlist);
+    TAILQ_INIT(&advlist);
+
+    printf("pci: enumerating %d buses\n", PCI_MAX_BUS);
     for (int i = 0; i < PCI_MAX_BUS; ++i) {
         pci_enum_bus(i);
     }
 
+    __MODULES_INIT(MODTYPE_PCI);
     printf("bridge: detected %d devices\n", devlist.nelem);
+
+    /* Now allocate load the drivers */
+    TAILQ_FOREACH(advp, &advlist, link) {
+        dev = advp->lookup;
+        lup = advp->classrev ? PCI_LU_CLASSREV : PCI_LU_VENDEV;
+
+        error = pci_bus_lookup(&dev, lup);
+        if (error == 0) {
+            advp->attach(advp);
+        }
+    }
 }