linux-kernel - [PATCH] regmap: Add hook for printk logging for debugging during early init

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Date:	Fri,  6 Jul 2012 14:14:05 +0100
From:	Mark Brown <broonie@...nsource.wolfsonmicro.com>
To:	linux-kernel@...r.kernel.org
Cc:	Mark Brown <broonie@...nsource.wolfsonmicro.com>
Subject: [PATCH] regmap: Add hook for printk logging for debugging during early init

Sometimes for failures during very early init the trace infrastructure
isn't available early enough to be used.  For this sort of problem
defining LOG_DEVICE will add printks for basic register I/O on a specific
device, allowing trace to be extracted when the trace system doesn't come
up early enough to work with.

Signed-off-by: Mark Brown <broonie@...nsource.wolfsonmicro.com>
---
 drivers/base/regmap/regmap.c |   19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/drivers/base/regmap/regmap.c b/drivers/base/regmap/regmap.c
index 13fc70b..c241ae2 100644
--- a/drivers/base/regmap/regmap.c
+++ b/drivers/base/regmap/regmap.c
@@ -22,6 +22,14 @@
 
 #include "internal.h"
 
+/*
+ * Sometimes for failures during very early init the trace
+ * infrastructure isn't available early enough to be used.  For this
+ * sort of problem defining LOG_DEVICE will add printks for basic
+ * register I/O on a specific device.
+ */
+#undef LOG_DEVICE
+
 static int _regmap_update_bits(struct regmap *map, unsigned int reg,
 			       unsigned int mask, unsigned int val,
 			       bool *change);
@@ -886,6 +894,11 @@ int _regmap_write(struct regmap *map, unsigned int reg,
 		}
 	}
 
+#ifdef LOG_DEVICE
+	if (strcmp(dev_name(map->dev), LOG_DEVICE) == 0)
+		dev_info(map->dev, "%x <= %x\n", reg, val);
+#endif
+
 	trace_regmap_reg_write(map->dev, reg, val);
 
 	if (map->format.format_write) {
@@ -1097,6 +1110,12 @@ static int _regmap_read(struct regmap *map, unsigned int reg,
 	ret = _regmap_raw_read(map, reg, map->work_buf, map->format.val_bytes);
 	if (ret == 0) {
 		*val = map->format.parse_val(map->work_buf);
+
+#ifdef LOG_DEVICE
+		if (strcmp(dev_name(map->dev), LOG_DEVICE) == 0)
+			dev_info(map->dev, "%x => %x\n", reg, *val);
+#endif
+
 		trace_regmap_reg_read(map->dev, reg, *val);
 	}
 
-- 
1.7.10

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