From dafae63886c6f97e03d436084a4b757f3137767e Mon Sep 17 00:00:00 2001
From: Ian Moffett <ian@osmora.org>
Date: Fri, 19 Sep 2025 21:48:10 -0400
Subject: 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>
---
 src/sys/io/ic/ahci.c | 81 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 81 insertions(+)
 create mode 100644 src/sys/io/ic/ahci.c

(limited to 'src/sys/io/ic')

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);
-- 
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