kernel: firmware loading

kernel-src/include/kernel/firmware.h

@@ -0,0 +1,11 @@
+#ifndef _FIRMWARE_H
+#define _FIRMWARE_H
+
+#include <stddef.h>
+
+typedef void (*firmware_callback_t)(void *ctx, void *data, size_t size);
+
+// firmware data is only valid only for the duration of the callback
+int firmware_load(const char *name, firmware_callback_t callback, void *ctx);
+
+#endif

kernel-src/io/firmware.c

@@ -0,0 +1,99 @@
+#include <kernel/firmware.h>
+#include <kernel/vfs.h>
+#include <kernel/alloc.h>
+#include <errno.h>
+
+#define FIRMWARE_SIZE_LIMIT (16 * 1024)
+#define FIRMWARE_PATH "/usr/lib/firmware/"
+
+typedef struct {
+	const char *name;
+	firmware_callback_t callback;
+	void *ctx;
+} firmware_ctx_t;
+
+static void do_load(void *ctx) {
+	firmware_ctx_t *fc = ctx;
+	printf("firmware: loading \"%s\"\n", fc->name);
+
+	vnode_t *firmware_dir;
+	int error = vfs_lookup(&firmware_dir, vfsroot, FIRMWARE_PATH, NULL, 0);
+	if (error) {
+		printf("firmware: loading \"%s\" failed: failed to open %s (%s)\n",
+			       	fc->name, FIRMWARE_PATH, strerror(error));
+		goto leave;
+	}
+
+	VOP_UNLOCK(firmware_dir); // vfs_lookup returns vnode locked
+
+	vnode_t *firmware_file;
+	error = vfs_lookup(&firmware_file, firmware_dir, fc->name, NULL, 0);
+	VOP_RELEASE(firmware_dir);
+	if (error) {
+		printf("firmware: loading \"%s\" failed: failed to open file (%s)\n", 
+				fc->name, strerror(error));
+		goto leave;
+	}
+
+	vattr_t vattr;
+	error = VOP_GETATTR(firmware_file, &vattr, NULL);
+	VOP_UNLOCK(firmware_file);
+	if (error)
+		goto leave_release;
+
+	if (vattr.size >= FIRMWARE_SIZE_LIMIT) {
+		error = EINVAL;
+		goto leave_release;
+	}
+
+	void *buffer = alloc(vattr.size);
+	if (buffer == NULL) {
+		error = ENOMEM;
+		goto leave_release;
+	}
+
+	size_t bytes_read;
+	error = vfs_read(firmware_file, buffer, vattr.size, 0, &bytes_read, 0); 
+	if (error)
+		goto leave_free;
+
+	if (bytes_read != vattr.size) {
+		error = EINVAL;
+		goto leave_free;
+	}
+
+	printf("firmware: \"%s\" loaded\n", fc->name);
+	fc->callback(fc->ctx, buffer, vattr.size);
+
+leave_free:
+	free(buffer);
+leave_release:
+	if (error) {
+		printf("firmware: loading \"%s\" failed: %s\n", 
+				fc->name, strerror(error));
+	}
+	VOP_RELEASE(firmware_file);
+leave:
+	free(fc);
+}
+
+int firmware_load(const char *name, firmware_callback_t callback, void *ctx) {
+	// TODO: support kernel embedded firmware
+	firmware_ctx_t *fc = alloc(sizeof(firmware_ctx_t));
+	if (fc == NULL)
+		return ENOMEM;
+
+	fc->name = name;
+	fc->callback = callback;
+	fc->ctx = ctx;
+
+	int error = vfs_root_event_attach(do_load, fc);
+	if (error && error != EBUSY) {
+		free(fc);
+		return error;
+	} else if (error == EBUSY) {
+		do_load(fc);
+	}
+
+	return 0;
+}