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 %pO\n", node);
A verbose format specifier (1-2) can be used to print extra
information about the node like its phandle and node flags.
Signed-off-by: Pantelis Antoniou <pantelis.antoniou@xxxxxxxxxxxx>
---
Documentation/printk-formats.txt | 18 +++++++++++
lib/vsprintf.c | 67 ++++++++++++++++++++++++++++++++++++++++
2 files changed, 85 insertions(+)
diff --git a/Documentation/printk-formats.txt b/Documentation/printk-formats.txt
index 5a615c1..6ad199f 100644
--- a/Documentation/printk-formats.txt
+++ b/Documentation/printk-formats.txt
@@ -231,6 +231,24 @@ struct va_format:
Do not use this feature without some mechanism to verify the
correctness of the format string and va_list arguments.
+Device tree nodes:
+
+ %pO{,1,2}
+
+ For printing device tree nodes. The (optional) number is the verbosity
+ level.
+
+ Examples:
+
+ %pO /foo/bar@0 - Node full name
+ %pO0 /foo/bar@0 - Same as above
+ %pO1 /foo/bar@0[10] - Node full name + phandle
+ %pO2 /foo/bar@0[10:DdPB] - Node full name + phandle + node flags
+ D - dynamic
+ d - detached
+ P - Populated
+ B - Populated bus
+
u64 SHOULD be printed with %llu/%llx:
printk("%llu", u64_var);
diff --git a/lib/vsprintf.c b/lib/vsprintf.c
index ec337f6..72896cc 100644
--- a/lib/vsprintf.c
+++ b/lib/vsprintf.c
@@ -29,6 +29,7 @@
#include <linux/dcache.h>
#include <linux/cred.h>
#include <net/addrconf.h>
+#include <linux/of.h>
#include <asm/page.h> /* for PAGE_SIZE */
#include <asm/sections.h> /* for dereference_function_descriptor() */
@@ -1240,6 +1241,68 @@ char *address_val(char *buf, char *end, const void *addr,
return number(buf, end, num, spec);
}
+#if IS_ENABLED(CONFIG_OF)
+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:xxxx]") + 1];
+ const char *full_name;
+ int verbosity, len, flen, i;
+
+ if ((unsigned long)dn < PAGE_SIZE)
+ return string(buf, end, "(null)", spec);
+
+ full_name = of_node_full_name(dn);
+ verbosity = 0;
+ if (fmt[1] >= '0' && fmt[1] <= '2')
+ verbosity = fmt[1] - '0';
+
+ /* fast and simple case */
+ switch (verbosity) {
+ default:
+ case 0:
+ tbuf[0] = '\0';
+ break;
+ case 1:
+ snprintf(tbuf, sizeof(tbuf), "[%u]",
+ (u32)dn->phandle);
+ break;
+ case 2:
+ snprintf(tbuf, sizeof(tbuf), "[%u:%c%c%c%c]",
+ (u32)dn->phandle,
+ 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' : '-');
+ break;
+ }
+ flen = strlen(full_name);
+ len = flen + strlen(tbuf);
+ if (spec.precision > 0 && len > spec.precision)
+ len = spec.precision;
+
+ if (!(spec.flags & LEFT)) {
+ while (len < spec.field_width--) {
+ if (buf < end)
+ *buf = ' ';
+ ++buf;
+ }
+ }
+ for (i = 0; i < len; ++i) {
+ if (buf < end)
+ *buf = i < flen ? full_name[i] : tbuf[i - flen];
+ ++buf;
+ }
+ while (len < spec.field_width--) {
+ if (buf < end)
+ *buf = ' ';
+ ++buf;
+ }
+ return buf;
+}
+#endif
+
int kptr_restrict __read_mostly;
/*
@@ -1459,6 +1522,10 @@ char *pointer(const char *fmt, char *buf, char *end, void *ptr,
return dentry_name(buf, end,
((const struct file *)ptr)->f_path.dentry,
spec, fmt);
+#if IS_ENABLED(CONFIG_OF)
+ case 'O':
+ return device_node_string(buf, end, ptr, spec, fmt);
+#endif
}
spec.flags |= SMALL;
if (spec.field_width == -1) {
--
1.7.12
--
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