mtd: Add MTD VFS wrapper for use with DevFS

drivers/include/mtd.h

@@ -23,6 +23,9 @@
 #define MTD_H
 
 #include <stdint.h>
+#if MODULE_VFS
+#include "vfs.h"
+#endif
 
 #ifdef __cplusplus
 extern "C" {
@@ -225,6 +228,13 @@ int mtd_erase(mtd_dev_t *mtd, uint32_t addr, uint32_t count);
  */
 int mtd_power(mtd_dev_t *mtd, enum mtd_power_state power);
 
+#if defined(MODULE_VFS) || defined(DOXYGEN)
+/**
+ * @brief MTD driver for VFS
+ */
+extern const vfs_file_ops_t mtd_vfs_ops;
+#endif
+
 #ifdef __cplusplus
 }
 #endif

drivers/mtd/mtd-vfs.c

@@ -0,0 +1,139 @@
+/*
+ * Copyright (C) 2016 Eistec AB
+ *
+ * This file is subject to the terms and conditions of the GNU Lesser General
+ * Public License v2.1. See the file LICENSE in the top level directory for more
+ * details.
+ */
+
+#if MODULE_VFS
+
+#include <fcntl.h>
+#include <errno.h>
+#include <unistd.h>
+
+#include "mtd.h"
+#include "vfs.h"
+
+/**
+ * @ingroup     mtd
+ * @{
+ *
+ * @file
+ *
+ * @brief       MTD generic VFS operations
+ *
+ * This allows the MTD driver to register as a node on DevFS
+ *
+ * See boards/mulle or tests/unittests/tests-devfs for examples on how to use.
+ *
+ * Tested with mtd_spi_nor on Mulle
+ *
+ * @author      Joakim Nohlgård <joakim.nohlgard@eistec.se>
+ */
+
+static int mtd_vfs_fstat(vfs_file_t *filp, struct stat *buf);
+static off_t mtd_vfs_lseek(vfs_file_t *filp, off_t off, int whence);
+static ssize_t mtd_vfs_read(vfs_file_t *filp, void *dest, size_t nbytes);
+static ssize_t mtd_vfs_write(vfs_file_t *filp, const void *src, size_t nbytes);
+
+const vfs_file_ops_t mtd_vfs_ops = {
+    .fstat = mtd_vfs_fstat,
+    .lseek = mtd_vfs_lseek,
+    .read  = mtd_vfs_read,
+    .write = mtd_vfs_write,
+};
+
+static int mtd_vfs_fstat(vfs_file_t *filp, struct stat *buf)
+{
+    if (buf == NULL) {
+        return -EFAULT;
+    }
+    mtd_dev_t *mtd = filp->private_data.ptr;
+    if (mtd == NULL) {
+        return -EFAULT;
+    }
+    buf->st_nlink = 1;
+    buf->st_size = mtd->page_size * mtd->sector_count * mtd->pages_per_sector;
+    return 0;
+}
+
+static off_t mtd_vfs_lseek(vfs_file_t *filp, off_t off, int whence)
+{
+    mtd_dev_t *mtd = filp->private_data.ptr;
+    if (mtd == NULL) {
+        return -EFAULT;
+    }
+    switch (whence) {
+        case SEEK_SET:
+            break;
+        case SEEK_CUR:
+            off += filp->pos;
+            break;
+        case SEEK_END:
+            off += mtd->page_size * mtd->sector_count * mtd->pages_per_sector;
+            break;
+        default:
+            return -EINVAL;
+    }
+    if (off < 0) {
+        /* the resulting file offset would be negative */
+        return -EINVAL;
+    }
+    /* POSIX allows seeking past the end of the file */
+    filp->pos = off;
+    return off;
+}
+
+static ssize_t mtd_vfs_read(vfs_file_t *filp, void *dest, size_t nbytes)
+{
+    mtd_dev_t *mtd = filp->private_data.ptr;
+    if (mtd == NULL) {
+        return -EFAULT;
+    }
+    uint32_t size = mtd->page_size * mtd->sector_count * mtd->pages_per_sector;
+    uint32_t src = filp->pos;
+    if (src >= size) {
+        return 0;
+    }
+    if ((src + nbytes) > size) {
+        nbytes = size - src;
+    }
+    int res = mtd_read(mtd, dest, src, nbytes);
+    if (res < 0) {
+        return res;
+    }
+    /* Advance file position */
+    filp->pos += res;
+    return res;
+}
+
+static ssize_t mtd_vfs_write(vfs_file_t *filp, const void *src, size_t nbytes)
+{
+    mtd_dev_t *mtd = filp->private_data.ptr;
+    if (mtd == NULL) {
+        return -EFAULT;
+    }
+    uint32_t size = mtd->page_size * mtd->sector_count * mtd->pages_per_sector;
+    uint32_t dest = filp->pos;
+    if (dest >= size) {
+        /* attempt to write outside the device memory */
+        return -ENOSPC;
+    }
+    if ((dest + nbytes) > size) {
+        nbytes = size - dest;
+    }
+    int res = mtd_write(mtd, src, dest, nbytes);
+    if (res < 0) {
+        return res;
+    }
+    /* Advance file position */
+    filp->pos += res;
+    return res;
+}
+
+/** @} */
+
+#else
+typedef int dont_be_pedantic;
+#endif /* MODULE_VFS */