[PATCH 3/4] of: Custom printk format specifier for device node
From: Rob Herring
Date: Wed Jun 14 2017 - 16:31:04 EST
From: Pantelis Antoniou <pantelis.antoniou@xxxxxxxxxxxx>
90% of the usage of device node's full_name is printing it out
in a kernel message. Preparing for the eventual delayed allocation
introduce a custom printk format specifier that is both more
compact and more pleasant to the eye.
For instance typical use is:
pr_info("Frobbing node %s\n", node->full_name);
Which can be written now as:
pr_info("Frobbing node %pOF\n", node);
More fine-grained control of formatting includes printing the name,
flag, path-spec name, reference count and others, explained in the
documentation entry.
Originally written by Pantelis, but pretty much rewrote the core
function using existing string/number functions. The 2 passes were
unnecessary and have been removed. Also, updated the checkpatch.pl
check.
Signed-off-by: Pantelis Antoniou <pantelis.antoniou@xxxxxxxxxxxx>
Signed-off-by: Rob Herring <robh@xxxxxxxxxx>
---
Documentation/printk-formats.txt | 31 +++++++++
lib/vsprintf.c | 135 ++++++++++++++++++++++++++++++++++++++-
scripts/checkpatch.pl | 2 +-
3 files changed, 166 insertions(+), 2 deletions(-)
diff --git a/Documentation/printk-formats.txt b/Documentation/printk-formats.txt
index 5962949944fd..07bc088ba5f5 100644
--- a/Documentation/printk-formats.txt
+++ b/Documentation/printk-formats.txt
@@ -275,6 +275,37 @@ struct va_format:
Passed by reference.
+Device tree nodes:
+
+ %pOF[fnpPcCFr]
+
+ For printing device tree nodes. The optional arguments are:
+ f device node full_name
+ n device node name
+ p device node phandle
+ P device node path spec (name + @unit)
+ F device node flags
+ c major compatible string
+ C full compatible string
+ r node reference count
+ Without any arguments prints full_name (same as %pOf)
+ The separator when using multiple arguments is '|'
+
+ Examples:
+
+ %pOF /foo/bar@0 - Node full name
+ %pOFf /foo/bar@0 - Same as above
+ %pOFfp /foo/bar@0|10 - Node full name + phandle
+ %pOFfcF /foo/bar@0|foo,device|--P- - Node full name +
+ major compatible string +
+ node flags
+ D - dynamic
+ d - detached
+ P - Populated
+ B - Populated bus
+
+ Passed by reference.
+
struct clk:
%pC pll1
diff --git a/lib/vsprintf.c b/lib/vsprintf.c
index 2d41de3f98a1..80b3e237f8d1 100644
--- a/lib/vsprintf.c
+++ b/lib/vsprintf.c
@@ -31,6 +31,7 @@
#include <linux/dcache.h>
#include <linux/cred.h>
#include <linux/uuid.h>
+#include <linux/of.h>
#include <net/addrconf.h>
#ifdef CONFIG_BLOCK
#include <linux/blkdev.h>
@@ -650,7 +651,7 @@ char *bdev_name(char *buf, char *end, struct block_device *bdev,
struct printf_spec spec, const char *fmt)
{
struct gendisk *hd = bdev->bd_disk;
-
+
buf = string(buf, end, hd->disk_name, spec);
if (bdev->bd_part->partno) {
if (isdigit(hd->disk_name[strlen(hd->disk_name)-1])) {
@@ -1470,6 +1471,123 @@ char *flags_string(char *buf, char *end, void *flags_ptr, const char *fmt)
return format_flags(buf, end, flags, names);
}
+static noinline_for_stack
+char *device_node_gen_full_name(const struct device_node *np, char *buf, char *end)
+{
+ int len, ret;
+
+ if (!np || !np->parent)
+ return buf;
+
+ buf = device_node_gen_full_name(np->parent, buf, end);
+
+ if (buf < end)
+ len = end - buf;
+ else
+ len = 0;
+ ret = snprintf(buf, len, "/%s", kbasename(np->full_name));
+ if (ret <= 0)
+ return buf;
+ else if (len == 0 || ret < len)
+ return buf + ret;
+ return buf + len;
+}
+
+static noinline_for_stack
+char *device_node_string(char *buf, char *end, struct device_node *dn,
+ struct printf_spec spec, const char *fmt)
+{
+ char tbuf[sizeof("xxxxxxxxxx") + 1];
+ const char *fmtp, *p;
+ int ret;
+ char *buf_start = buf;
+ struct property *prop;
+ bool has_mult, pass;
+ const struct printf_spec num_spec = {
+ .flags = SMALL,
+ .field_width = -1,
+ .precision = -1,
+ .base = 10,
+ };
+
+ struct printf_spec str_spec = spec;
+ str_spec.field_width = -1;
+
+ if (!IS_ENABLED(CONFIG_OF))
+ return string(buf, end, "(!OF)", spec);
+
+ if ((unsigned long)dn < PAGE_SIZE)
+ return string(buf, end, "(null)", spec);
+
+ /* simple case without anything any more format specifiers */
+ if (fmt[1] == '\0' || strcspn(fmt + 1,"fnpPFcCr") > 0)
+ fmt = "Ff";
+
+ for (fmtp = fmt + 1, pass = false; strspn(fmtp,"fnpPFcCr"); fmtp++, pass = true) {
+ if (pass && (*fmtp != 'f')) {
+ if (buf < end)
+ *buf = '|';
+ buf++;
+ }
+
+ switch (*fmtp) {
+ case 'f': /* full_name */
+ if (pass) {
+ if (buf < end)
+ *buf = ':';
+ buf++;
+ }
+ buf = device_node_gen_full_name(dn, buf, end);
+ break;
+ case 'n': /* name */
+ buf = string(buf, end, dn->name, str_spec);
+ break;
+ case 'p': /* phandle */
+ buf = number(buf, end, (unsigned int)dn->phandle, num_spec);
+ break;
+ case 'P': /* path-spec */
+ buf = string(buf, end, kbasename(of_node_full_name(dn)), str_spec);
+ break;
+ case 'F': /* flags */
+ snprintf(tbuf, sizeof(tbuf), "%c%c%c%c",
+ of_node_check_flag(dn, OF_DYNAMIC) ?
+ 'D' : '-',
+ of_node_check_flag(dn, OF_DETACHED) ?
+ 'd' : '-',
+ of_node_check_flag(dn, OF_POPULATED) ?
+ 'P' : '-',
+ of_node_check_flag(dn,
+ OF_POPULATED_BUS) ? 'B' : '-');
+ buf = string(buf, end, tbuf, str_spec);
+ break;
+ case 'c': /* major compatible string */
+ ret = of_property_read_string(dn, "compatible", &p);
+ if (!ret)
+ buf = string(buf, end, p, str_spec);
+ break;
+ case 'C': /* full compatible string */
+ has_mult = false;
+ of_property_for_each_string(dn, "compatible", prop, p) {
+ if (has_mult)
+ buf = string(buf, end, ",", str_spec);
+ buf = string(buf, end, "\"", str_spec);
+ buf = string(buf, end, p, str_spec);
+ buf = string(buf, end, "\"", str_spec);
+
+ has_mult = true;
+ }
+ break;
+ case 'r': /* node reference count */
+ buf = number(buf, end, refcount_read(&dn->kobj.kref.refcount), num_spec);
+ break;
+ default:
+ break;
+ }
+ }
+
+ return widen_string(buf, buf - buf_start, end, spec);
+}
+
int kptr_restrict __read_mostly;
/*
@@ -1566,6 +1684,16 @@ int kptr_restrict __read_mostly;
* p page flags (see struct page) given as pointer to unsigned long
* g gfp flags (GFP_* and __GFP_*) given as pointer to gfp_t
* v vma flags (VM_*) given as pointer to unsigned long
+ * - 'OF[fnpPcCFr]' For an DT device node
+ * Without any optional arguments prints the full_name
+ * f device node full_name
+ * n device node name
+ * p device node phandle
+ * P device node path spec (name + @unit)
+ * F device node flags
+ * c major compatible string
+ * C full compatible string
+ * r node reference count
*
* ** Please update also Documentation/printk-formats.txt when making changes **
*
@@ -1721,6 +1849,11 @@ char *pointer(const char *fmt, char *buf, char *end, void *ptr,
case 'G':
return flags_string(buf, end, ptr, fmt);
+ case 'O':
+ switch (fmt[1]) {
+ case 'F':
+ return device_node_string(buf, end, ptr, spec, fmt + 1);
+ }
}
spec.flags |= SMALL;
if (spec.field_width == -1) {
diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
index 4b9569fa931b..411f2098fa6b 100755
--- a/scripts/checkpatch.pl
+++ b/scripts/checkpatch.pl
@@ -5709,7 +5709,7 @@ sub process {
for (my $count = $linenr; $count <= $lc; $count++) {
my $fmt = get_quoted_string($lines[$count - 1], raw_line($count, 0));
$fmt =~ s/%%//g;
- if ($fmt =~ /(\%[\*\d\.]*p(?![\WFfSsBKRraEhMmIiUDdgVCbGN]).)/) {
+ if ($fmt =~ /(\%[\*\d\.]*p(?![\WFfSsBKRraEhMmIiUDdgVCbGNO]).)/) {
$bad_extension = $1;
last;
}
--
2.11.0