On Tue, Nov 25, 2014 at 12:07:29PM +0000, Ian Campbell wrote:
> My concern is that this is Linux specific, other OSes may have different
> ideas about how stdout options should be formatted within this property.
> (At least I don't know of any standardisation of the 115200n8 thing --
> I'd love to be corrected!)
>
> If I were a firmware author I'd be wary of specifying a stdout-path with
> a Linux specific suffix.
> Search ePAPR for baud it seems that the generic serial binding includes
> a current-speed property in 6.2.1.2. It then goes on a bit ambiguously
> to talk about the NS16550 in 6.2.2 but I think 6.2.1.2 was intended to
> be generic. No mention of stop-bits/parity etc though, they are assumed
> to be set already I think
>
> One thought I had was to define a dt-stdout "pseudo-console" so that
> console=dt-stdout,115200n8 or something could be used.
I'll wait for others to comment on the above.
> Anyway I applied your patch to v3.18-rc5 and ran it on a Mustang and it
> didn't work for some reason. I'm using:
>
> fdt set /chosen stdout-path "/soc/serial@1c020000:115200"
> setenv bootargs "earlycon=uart8250,mmio32,0x1c020000 root=/dev/sda3 rw debug"
>
> So I get earlycon but then no proper console. Removing earlycon just
> makes that stop working.
Right, so having debugged this a bit offline, I'm amazed I booted
anything at all, given how badly I broke path scanning...
Please ignore previous version - a fixed one follows:
/
Leif
>From aef87fd958902afe881720286d525e10997462b8 Mon Sep 17 00:00:00 2001
From: Leif Lindholm <leif.lindholm@xxxxxxxxxx>
Date: Mon, 24 Nov 2014 22:23:58 +0000
Subject: [PATCH] of: support passing console options with stdout-path
Support specifying console options (like with console=ttyXN,<options>)
by appending them to the stdout-path property after a separating ':'.
Example:
stdout-path = "uart0:115200";
This patch also modifies of_find_node_by_path() to match only the
portion of the path before a ':'.
Signed-off-by: Leif Lindholm <leif.lindholm@xxxxxxxxxx>
---
drivers/of/base.c | 19 +++++++++++++++++--
1 file changed, 17 insertions(+), 2 deletions(-)
diff --git a/drivers/of/base.c b/drivers/of/base.c
index 3823edf..ecd6290 100644
--- a/drivers/of/base.c
+++ b/drivers/of/base.c
@@ -37,6 +37,7 @@ EXPORT_SYMBOL(of_allnodes);
struct device_node *of_chosen;
struct device_node *of_aliases;
struct device_node *of_stdout;
+static char *of_stdout_options;
struct kset *of_kset;
@@ -699,10 +700,15 @@ static struct device_node *__of_find_node_by_path(struct device_node *parent,
{
struct device_node *child;
int len = strchrnul(path, '/') - path;
+ int term;
if (!len)
return NULL;
+ term = strchrnul(path, ':') - path;
+ if (term < len)
+ len = term;
+
__for_each_child_of_node(parent, child) {
const char *name = strrchr(child->full_name, '/');
if (WARN(!name, "malformed device_node %s\n", child->full_name))
@@ -742,11 +748,16 @@ struct device_node *of_find_node_by_path(const char *path)
if (*path != '/') {
char *p = strchrnul(path, '/');
int len = p - path;
+ int term;
/* of_aliases must not be NULL */
if (!of_aliases)
return NULL;
+ term = strchrnul(path, ':') - path;
+ if (term < len)
+ len = term;
+
for_each_property_of_node(of_aliases, pp) {
if (strlen(pp->name) == len && !strncmp(pp->name, path, len)) {
np = of_find_node_by_path(pp->value);
@@ -1830,8 +1841,12 @@ void of_alias_scan(void * (*dt_alloc)(u64 size, u64 align))
name = of_get_property(of_chosen, "linux,stdout-path", NULL);
if (IS_ENABLED(CONFIG_PPC) && !name)
name = of_get_property(of_aliases, "stdout", NULL);
- if (name)
+ if (name) {
of_stdout = of_find_node_by_path(name);
+ of_stdout_options = strchr(name, ':');
+ if (of_stdout_options != NULL)
+ of_stdout_options++;
+ }
}
if (!of_aliases)
@@ -1957,7 +1972,7 @@ bool of_console_check(struct device_node *dn, char *name, int index)
{
if (!dn || dn != of_stdout || console_set_on_cmdline)
return false;
- return !add_preferred_console(name, index, NULL);
+ return !add_preferred_console(name, index, of_stdout_options);
}
EXPORT_SYMBOL_GPL(of_console_check);
--
1.7.10.4
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