debugfs: add 9p device interface
The 9p interface provides abstraction layers allowing the software
that uses devices to be independent from the hardware.
This patch provides a file system abstraction to link drivers to their
devices and propose a common interface to expose driver operations to
higher layers. This file system can be used to access and configure a
device by doing read/write operations.
Signed-off-by: Ambroise Vincent <ambroise.vincent@arm.com>
Signed-off-by: Olivier Deprez <olivier.deprez@arm.com>
Change-Id: Ia9662393baf489855dc0c8f389fe4a0afbc9c255
diff --git a/lib/debugfs/dev.h b/lib/debugfs/dev.h
new file mode 100644
index 0000000..c142651
--- /dev/null
+++ b/lib/debugfs/dev.h
@@ -0,0 +1,120 @@
+/*
+ * Copyright (c) 2019, Arm Limited. All rights reserved.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#ifndef DEV_H
+#define DEV_H
+
+#include <cdefs.h>
+#include <lib/debugfs.h>
+#include <stddef.h>
+
+/* FIXME: need configurability */
+#define NR_CHANS 10
+#define NR_CONSS 1
+#define NR_BINDS 4
+#define NR_FILES 18
+
+#define NODEV 255
+#define CHDIR (1 << 15)
+
+#define SYNCDEV 0
+#define SYNCALL 1
+
+typedef struct dev dev_t;
+typedef struct chan chan_t;
+typedef struct dirtab dirtab_t;
+typedef int devgen_t(chan_t *, const dirtab_t *, int, int, dir_t *);
+typedef struct attr attr_t;
+
+enum {
+ DEV_ROOT_QROOT,
+ DEV_ROOT_QDEV,
+ DEV_ROOT_QFIP,
+ DEV_ROOT_QBLOBS,
+ DEV_ROOT_QBLOBCTL,
+ DEV_ROOT_QPSCI
+};
+
+/*******************************************************************************
+ * This structure contains the necessary information to represent a directory
+ * of the filesystem.
+ ******************************************************************************/
+struct dirtab {
+ char name[NAMELEN];
+ qid_t qid;
+ long length;
+ unsigned char perm;
+ void *data;
+};
+
+/*******************************************************************************
+ * This structure defines the interface of device drivers.
+ * Each driver must implement a subset of those functions.
+ * It is possible to redirect to default implementations defined in dev.c.
+ ******************************************************************************/
+/* FIXME: comments for the callbacks */
+struct dev {
+ char id;
+ int (*stat)(chan_t *c, const char *file, dir_t *dir);
+ int (*walk)(chan_t *c, const char *name);
+ int (*read)(chan_t *c, void *buf, int n);
+ int (*write)(chan_t *c, void *buf, int n);
+ int (*seek)(chan_t *c, long off, int whence);
+ chan_t *(*clone)(chan_t *c, chan_t *nc);
+ chan_t *(*attach)(int id, int dev);
+ chan_t *(*mount)(chan_t *c, const char *spec);
+};
+
+/*******************************************************************************
+ * This structure defines the channel structure.
+ * A channel is a handle on an element of the filesystem.
+ ******************************************************************************/
+struct chan {
+ long offset;
+ qid_t qid;
+ unsigned char index; /* device index in devtab */
+ unsigned char dev;
+ unsigned char mode;
+};
+
+/*******************************************************************************
+ * This structure defines an abstract argument passed to physical drivers from
+ * the configuration file.
+ ******************************************************************************/
+struct attr {
+ char *key;
+ char *value;
+};
+
+chan_t *path_to_channel(const char *path, int mode);
+chan_t *clone(chan_t *c, chan_t *nc);
+chan_t *attach(int id, int dev);
+void channel_close(chan_t *c);
+int buf_to_channel(chan_t *c, void *dst, void *src, int nbytes, long len);
+int dirread(chan_t *c, dir_t *dir, const dirtab_t *tab,
+ int ntab, devgen_t *gen);
+void make_dir_entry(chan_t *c, dir_t *dir, const char *name, long length,
+ qid_t qid, unsigned int mode);
+void devlink(void);
+
+chan_t *devattach(int id, int dev);
+int devseek(chan_t *c, long off, int whence);
+chan_t *devclone(chan_t *c, chan_t *nc);
+int devgen(chan_t *c, const dirtab_t *tab, int ntab, int n, dir_t *dir);
+int devwalk(chan_t *c, const char *name, const dirtab_t *tab, int ntab,
+ devgen_t *gen);
+int devstat(chan_t *dirc, const char *file, dir_t *dir,
+ const dirtab_t *tab, int ntab, devgen_t *gen);
+
+chan_t *deverrmount(chan_t *c, const char *spec);
+int deverrwrite(chan_t *c, void *buf, int n);
+int deverrseek(chan_t *c, long off, int whence);
+
+extern dev_t *const devtab[];
+
+void __dead2 devpanic(const char *cause);
+
+#endif /* DEV_H */