port-evbarm/47250: Add passing of bootargs from U-Boot for Marvell SheevaPlug

[toby.karyadi%gmail.com@localhost]

>Number:         47250
>Category:       port-evbarm
>Synopsis:       Add passing of bootargs from U-Boot for Marvell SheevaPlug
>Confidential:   no
>Severity:       non-critical
>Priority:       medium
>Responsible:    port-evbarm-maintainer
>State:          open
>Class:          change-request
>Submitter-Id:   net
>Arrival-Date:   Mon Nov 26 19:50:00 +0000 2012
>Originator:     Toby Karyadi
>Release:        current
>Organization:
>Environment:
NetBSD kowari.simplecubes.com 6.99.15 NetBSD 6.99.15 (SHEEVAAXE) #6: Mon Nov 26 
12:36:10 EST 2012  
archie%zutu.simplecubes.com@localhost:/mnt/v01/build/src/current/2012.11.17.05.20.00/obj/sys/arch/evbarm/compile/SHEEVAAXE
 evbarm

>Description:
The intent of the patchset below is to allow specifying the root device and 
boothowto via U-Boot's special bootargs environment variable. 

Example:
Marvell>> env print bootcmd
bootcmd=mmc init; fatload mmc 0:1 0x1000000 netbsd.ub; setenv bootargs 
root=ld0a; bootm 0x1000000;

With the bootcmd U-Boot env var setup like above, U-Boot's 'boot' cmd would 
just boot up my netbsd filesystem on the sdcard. It would also allow booting up 
in single user mode, break in the debugger, etc, e.g.:

# Start in single user mode
setenv bootargs root=ld0a -s
# ... or
setenv bootargs root=ld0a single
# Invoke kernel debugger
setenv bootargs root=ld0a kdb

I believe most of the boot arg options are defined in 
arm32_machdep.c:parse_mi_bootargs(), I might be wrong, but at any rate, they 
are similar to the ones described in boot(8).

The code in evbarm/evbarm/autoconf.c is basically swipped/modeled after other 
archs, like acorn32, hpcarm, but specifically shark/shark. I don't know how 
this affects other evbarm based devices, but I suspect it's benign, but I have 
no way of testing it. In netbsd-6, the changes in evbarm/evbarm/autoconf.c 
would have been sufficient, however, recent boot init code refactoring work 
between beagle and marvell also seemed to have accidentally removed the code to 
setup the boot_args value based on the bootargs value read in from U-Boot in 
marvell_machdep.c. 

I've tested the code and it works as intended, but please review. The patch 
applies cleanly against current as of 2012.11.17.05.20.00.
>How-To-Repeat:
N/A.
>Fix:
--- src/sys/arch/evbarm/marvell/marvell_machdep.c.orig  2012-10-22 
11:43:32.000000000 -0400
+++ src/sys/arch/evbarm/marvell/marvell_machdep.c       2012-11-26 
13:30:04.000000000 -0500
@@ -375,6 +375,10 @@
        /* we've a specific device_register routine */
        evbarm_device_register = marvell_device_register;
 
+       /* parse bootargs from U-Boot */
+       boot_args = bootargs;
+       parse_mi_bootargs(boot_args);
+
        return initarm_common(KERNEL_VM_BASE, KERNEL_VM_SIZE, NULL, 0);
 }
 
--- src/sys/arch/evbarm/evbarm/autoconf.c.orig  2012-10-27 13:17:46.000000000 
-0400
+++ src/sys/arch/evbarm/evbarm/autoconf.c       2012-11-26 13:09:31.000000000 
-0500
@@ -45,15 +45,73 @@
 
 #include <machine/autoconf.h>
 #include <machine/intr.h>
+#include <machine/bootconfig.h>
 
 void   (*evbarm_device_register)(device_t, void *);
 
+#ifndef MEMORY_DISK_IS_ROOT
+static void get_device(char *name);
+static void set_root_device(void);
+#endif
+
+#ifndef MEMORY_DISK_IS_ROOT
+/* Decode a device name to a major and minor number */
+
+static void
+get_device(char *name)
+{
+       int unit, part;
+       char devname[16], *cp;
+       device_t dv;
+       
+       if (strncmp(name, "/dev/", 5) == 0)
+               name += 5;
+       
+       if (devsw_name2blk(name, devname, sizeof(devname)) == -1)
+               return;
+       
+       name += strlen(devname);
+       unit = part = 0;
+       
+       cp = name;
+       while (*cp >= '0' && *cp <= '9')
+               unit = (unit * 10) + (*cp++ - '0');
+       if (cp == name)
+               return;
+       
+       if (*cp >= 'a' && *cp <= ('a' + MAXPARTITIONS))
+               part = *cp - 'a';
+       else if (*cp != '\0' && *cp != ' ')
+               return;
+       if ((dv = device_find_by_driver_unit(devname, unit)) != NULL) {
+               booted_device = dv;
+               booted_partition = part;
+       }
+}
+
+
+/* Set the rootdev variable from the root specifier in the boot args */
+
+static void
+set_root_device(void)
+{
+       char *ptr;
+
+       if (boot_args &&
+               get_bootconf_option(boot_args, "root", BOOTOPT_TYPE_STRING, 
&ptr))
+               get_device(ptr);
+}
+#endif
+
 /*
  * Set up the root device from the boot args
  */
 void
 cpu_rootconf(void)
 {
+#ifndef MEMORY_DISK_IS_ROOT
+        set_root_device();
+#endif
        aprint_normal("boot device: %s\n",
            booted_device != NULL ? device_xname(booted_device) : "<unknown>");
        rootconf();