blspec: automatically append bootargs

When bootloader spec is used to boot devices it is often desirable
to boot the same image from different media. Since the fs images
need to contain the root= parameters to tell Linux where to boot
from the images can't be identical on different media.

This patch changes this by introducing a 'appendroot' option for
bootloader spec. If set to true, barebox will construct a Linux
commandline option for the device the bootloader spec entry is found
on.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

common/blspec.c

@@ -622,6 +622,41 @@ int blspec_scan_devicename(struct blspec *blspec, const char *devname)
 	return blspec_scan_device(blspec, dev);
 }
 
+static int blspec_append_root(struct blspec_entry *entry)
+{
+	const char *appendroot;
+	const char *rootarg;
+	struct device_d *fsdev;
+	int ret;
+
+	appendroot = blspec_entry_var_get(entry, "appendroot");
+	if (!appendroot || strcmp(appendroot, "true"))
+		return 0;
+
+	fsdev = get_dev_by_mountpath(entry->rootpath);
+	if (!fsdev) {
+		ret = -EINVAL;
+		pr_err("Cannot get fs device for %s\n", entry->rootpath);
+		goto err_out;
+	}
+
+	rootarg = dev_get_param(fsdev, "linux.bootargs");
+	if (!rootarg) {
+		ret = -EINVAL;
+		pr_err("rootarg not implemented for fs %s\n", dev_name(fsdev));
+		goto err_out;
+	}
+
+	globalvar_add_simple("linux.bootargs.dyn.blspec.appendroot", rootarg);
+
+	return 0;
+
+err_out:
+	pr_err("unable to append root argument\n");
+
+	return ret;
+}
+
 /*
  * blspec_boot - boot an entry
  *
@@ -671,6 +706,10 @@ int blspec_boot(struct blspec_entry *entry, int verbose, int dryrun)
 
 	globalvar_add_simple("linux.bootargs.dyn.blspec", options);
 
+	ret = blspec_append_root(entry);
+	if (ret)
+		goto err_out;
+
 	pr_info("booting %s from %s\n", blspec_entry_var_get(entry, "title"),
 			entry->cdev ? dev_name(entry->cdev->dev) : "none");
 
@@ -689,7 +728,7 @@ int blspec_boot(struct blspec_entry *entry, int verbose, int dryrun)
 	ret = bootm_boot(&data);
 	if (ret)
 		pr_err("Booting failed\n");
-
+err_out:
 	free((char *)data.oftree_file);
 	free((char *)data.initrd_file);
 	free((char *)data.os_file);

drivers/mtd/ubi/kapi.c

@@ -36,6 +36,7 @@ void ubi_do_get_device_info(struct ubi_device *ubi, struct ubi_device_info *di)
 	di->min_io_size = ubi->min_io_size;
 	di->max_write_size = ubi->max_write_size;
 	di->ro_mode = ubi->ro_mode;
+	di->mtd = ubi->mtd;
 }
 EXPORT_SYMBOL_GPL(ubi_do_get_device_info);
 

fs/fs.c

@@ -225,6 +225,19 @@ struct cdev *get_cdev_by_mountpath(const char *path)
 	return fsdev->cdev;
 }
 
+/*
+ * get_cdev_by_mountpath - return the cdev the given path
+ *                         is mounted on
+ */
+struct device_d *get_dev_by_mountpath(const char *path)
+{
+	struct fs_device_d *fsdev;
+
+	fsdev = get_fsdevice_by_path(path);
+
+	return &fsdev->dev;
+}
+
 char *get_mounted_path(const char *path)
 {
 	struct fs_device_d *fdev;

fs/nfs.c

@@ -1306,6 +1306,20 @@ static int nfs_stat(struct device_d *dev, const char *filename, struct stat *s)
 	}
 }
 
+static void nfs_set_rootarg(struct nfs_priv *npriv, struct device_d *dev)
+{
+	char *str;
+	const char *ip;
+
+	ip = ip_to_string(npriv->server);
+	str = asprintf("root=/dev/nfs nfsroot=%s:%s,v3,tcp",
+			ip, npriv->path);
+
+	dev_add_param_fixed(dev, "linux.bootargs", str);
+
+	free(str);
+}
+
 static int nfs_probe(struct device_d *dev)
 {
 	struct fs_device_d *fsdev = dev_to_fs_device(dev);
@@ -1369,6 +1383,8 @@ static int nfs_probe(struct device_d *dev)
 		goto err2;
 	}
 
+	nfs_set_rootarg(npriv, dev);
+
 	free(tmp);
 
 	return 0;

fs/ubifs/ubifs.c

@@ -36,6 +36,7 @@
 #include <linux/zlib.h>
 #include <xfuncs.h>
 #include <fcntl.h>
+#include <linux/mtd/mtd.h>
 
 #include "ubifs.h"
 
@@ -584,6 +585,26 @@ static int ubifs_readlink(struct device_d *dev, const char *pathname, char *buf,
 	return 0;
 }
 
+static void ubifs_set_rootarg(struct ubifs_priv *priv, struct device_d *dev)
+{
+	struct ubi_volume_info vi = {};
+	struct ubi_device_info di = {};
+	struct mtd_info *mtd;
+	char *str;
+
+	ubi_get_volume_info(priv->ubi, &vi);
+	ubi_get_device_info(vi.ubi_num, &di);
+
+	mtd = di.mtd;
+
+	str = asprintf("root=ubi0:%s ubi.mtd=%s rootfstype=ubifs",
+			vi.name, mtd->cdev.partname);
+
+	dev_add_param_fixed(dev, "linux.bootargs", str);
+
+	free(str);
+}
+
 static int ubifs_probe(struct device_d *dev)
 {
 	struct fs_device_d *fsdev = dev_to_fs_device(dev);
@@ -612,6 +633,8 @@ static int ubifs_probe(struct device_d *dev)
 		goto err;
 	}
 
+	ubifs_set_rootarg(priv, dev);
+
 	return 0;
 err:
 	ubi_close_volume(priv->ubi);

include/fs.h

@@ -174,6 +174,7 @@ char *normalise_link(const char *pathname, const char* symlink);
 char *get_mounted_path(const char *path);
 
 struct cdev *get_cdev_by_mountpath(const char *path);
+struct device_d *get_dev_by_mountpath(const char *path);
 
 /* Register a new filesystem driver */
 int register_fs_driver(struct fs_driver_d *fsdrv);

include/linux/mtd/ubi.h

@@ -154,6 +154,7 @@ struct ubi_device_info {
 	int max_write_size;
 	int ro_mode;
 	dev_t cdev;
+	struct mtd_info *mtd;
 };
 
 /*