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);
More fine-grained control of formatting includes printing the name,
flag, path-spec name, reference count and others, explained in the
documentation entry.
Signed-off-by: Pantelis Antoniou <pantelis.antoniou@xxxxxxxxxxxx>
dt-print
---
Documentation/printk-formats.txt | 29 ++++++++
lib/vsprintf.c | 151 +++++++++++++++++++++++++++++++++++++++
2 files changed, 180 insertions(+)
diff --git a/Documentation/printk-formats.txt b/Documentation/printk-formats.txt
index 5a615c1..2d42c04 100644
--- a/Documentation/printk-formats.txt
+++ b/Documentation/printk-formats.txt
@@ -231,6 +231,35 @@ 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[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:
+
+ %pO /foo/bar@0 - Node full name
+ %pOf /foo/bar@0 - Same as above
+ %pOfp /foo/bar@0|10 - Node full name + phandle
+ %pOfcF /foo/bar@0|foo,device|--P- - Node full name +
+ major compatible string +
+ 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..f3e49b9 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 +1241,144 @@ char *address_val(char *buf, char *end, const void *addr,
return number(buf, end, num, spec);
}
+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 len, ret, i, j, pass;
+ char c;
+
+ 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' || isspace(fmt[1]))
+ fmt = "Of";
+
+ len = 0;
+
+ /* two passes; the first calculates length, the second fills in */
+ for (pass = 1; pass <= 2; pass++) {
+ if (pass == 2 && !(spec.flags & LEFT)) {
+ /* padding */
+ while (len < spec.field_width--) {
+ if (buf < end)
+ *buf = ' ';
+ ++buf;
+ }
+ }
+#undef _HANDLE_CH
+#define _HANDLE_CH(_ch) \
+ do { \
+ if (pass == 1) \
+ len++; \
+ else \
+ if (buf < end) \
+ *buf++ = (_ch); \
+ } while (0)
+#undef _HANDLE_STR
+#define _HANDLE_STR(_str) \
+ do { \
+ const char *str = (_str); \
+ if (pass == 1) \
+ len += strlen(str); \
+ else \
+ while (*str && buf < end) \
+ *buf++ = *str++; \
+ } while (0)
+
+ for (fmtp = fmt + 1, j = 0; (c = *fmtp++) != '\0'; ) {
+ switch (c) {
+ case 'f': /* full_name */
+ if (j++ > 0)
+ _HANDLE_CH(':');
+ _HANDLE_STR(of_node_full_name(dn));
+ break;
+ case 'n': /* name */
+ if (j++ > 0)
+ _HANDLE_CH('|');
+ _HANDLE_STR(dn->name);
+ break;
+ case 'p': /* phandle */
+ if (j++ > 0)
+ _HANDLE_CH('|');
+ snprintf(tbuf, sizeof(tbuf), "%u",
+ (unsigned int)dn->phandle);
+ _HANDLE_STR(tbuf);
+ break;
+ case 'P': /* path-spec */
+ if (j++ > 0)
+ _HANDLE_CH('|');
+ _HANDLE_STR(dn->name);
+ /* need to tack on the @ postfix */
+ p = strchr(of_node_full_name(dn), '@');
+ if (p)
+ _HANDLE_STR(p);
+ break;
+ case 'F': /* flags */
+ if (j++ > 0)
+ _HANDLE_CH('|');
+ 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' : '-');
+ _HANDLE_STR(tbuf);
+ break;
+ case 'c': /* major compatible string */
+ if (j++ > 0)
+ _HANDLE_CH('|');
+ ret = of_property_read_string(dn, "compatible",
+ &p);
+ if (ret == 0)
+ _HANDLE_STR(p);
+ break;
+ case 'C': /* full compatible string */
+ if (j++ > 0)
+ _HANDLE_CH('|');
+ i = 0;
+ while (of_property_read_string_index(dn,
+ "compatible", i, &p) == 0) {
+ if (i == 0)
+ _HANDLE_STR("\"");
+ else
+ _HANDLE_STR("\",\"");
+ _HANDLE_STR(p);
+ i++;
+ }
+ if (i > 0)
+ _HANDLE_STR("\"");
+ break;
+ case 'r': /* node reference count */
+ if (j++ > 0)
+ _HANDLE_CH('|');
+ snprintf(tbuf, sizeof(tbuf), "%u",
+ atomic_read(&dn->kobj.kref.refcount));
+ _HANDLE_STR(tbuf);
+ break;
+ default:
+ break;
+ }
+ }
+ }
+ /* finish up */
+ while (buf < end && len < spec.field_width--)
+ *buf++ = ' ';
+#undef _HANDLE_CH
+#undef _HANDLE_STR
+
+ return buf;
+}
+
int kptr_restrict __read_mostly;
/*
@@ -1318,6 +1457,16 @@ int kptr_restrict __read_mostly;
* (default assumed to be phys_addr_t, passed by reference)
* - 'd[234]' For a dentry name (optionally 2-4 last components)
* - 'D[234]' Same as 'd' but for a struct file
+ * - 'O[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
*
* Note: The difference between 'S' and 'F' is that on ia64 and ppc64
* function pointers are really function descriptors, which contain a
@@ -1459,6 +1608,8 @@ 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);
+ case 'O':
+ return device_node_string(buf, end, ptr, spec, fmt);
}
spec.flags |= SMALL;
if (spec.field_width == -1) {
--
1.7.12
--
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