regmap: Provide register map dump via debugfs

Copy over the read parts of the ASoC debugfs implementation into regmap,
allowing users to see what the register values the device has are at
runtime. The implementation, especially the support for seeking, is
mostly due to Dimitris Papastamos' work in ASoC.
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>

drivers/base/regmap/Makefile

 obj-$(CONFIG_REGMAP) += regmap.o
+obj-$(CONFIG_DEBUG_FS) += regmap-debugfs.o
 obj-$(CONFIG_REGMAP_I2C) += regmap-i2c.o
 obj-$(CONFIG_REGMAP_SPI) += regmap-spi.o

drivers/base/regmap/internal.h

@@ -14,6 +14,7 @@
 #define _REGMAP_INTERNAL_H
 
 #include <linux/regmap.h>
+#include <linux/fs.h>
 
 struct regmap;
 
@@ -36,10 +37,24 @@ struct regmap {
 	struct regmap_format format;  /* Buffer format */
 	const struct regmap_bus *bus;
 
+#ifdef CONFIG_DEBUG_FS
+	struct dentry *debugfs;
+#endif
+
 	unsigned int max_register;
 	bool (*writeable_reg)(struct device *dev, unsigned int reg);
 	bool (*readable_reg)(struct device *dev, unsigned int reg);
 	bool (*volatile_reg)(struct device *dev, unsigned int reg);
 };
 
+#ifdef CONFIG_DEBUG_FS
+extern void regmap_debugfs_initcall(void);
+extern void regmap_debugfs_init(struct regmap *map);
+extern void regmap_debugfs_exit(struct regmap *map);
+#else
+void regmap_debugfs_initcall(void) { }
+void regmap_debugfs_init(struct regmap *map) { }
+void regmap_debugfs_exit(struct regmap *map) { }
+#endif
+
 #endif

drivers/base/regmap/regmap-debugfs.c

+/*
+ * Register map access API - debugfs
+ *
+ * Copyright 2011 Wolfson Microelectronics plc
+ *
+ * Author: Mark Brown <broonie@opensource.wolfsonmicro.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <linux/slab.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/debugfs.h>
+#include <linux/uaccess.h>
+
+#include "internal.h"
+
+static struct dentry *regmap_debugfs_root;
+
+static int regmap_map_open_file(struct inode *inode, struct file *file)
+{
+	file->private_data = inode->i_private;
+	return 0;
+}
+
+static ssize_t regmap_map_read_file(struct file *file, char __user *user_buf,
+				    size_t count, loff_t *ppos)
+{
+	size_t reg_len, val_len, tot_len;
+	size_t buf_pos = 0;
+	loff_t p = 0;
+	ssize_t ret;
+	int i;
+	struct regmap *map = file->private_data;
+	char *buf;
+	unsigned int val;
+
+	if (*ppos < 0 || !count)
+		return -EINVAL;
+
+	buf = kmalloc(count, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+
+	/* Calculate the length of a fixed format  */
+	snprintf(buf, count, "%x", map->max_register);
+	reg_len = strlen(buf);
+	val_len = 2 * map->format.val_bytes;
+	tot_len = reg_len + val_len + 3;      /* : \n */
+
+	for (i = 0; i < map->max_register; i++) {
+		if (map->readable_reg &&
+		    !map->readable_reg(map->dev, i))
+			continue;
+
+		/* If we're in the region the user is trying to read */
+		if (p >= *ppos) {
+			/* ...but not beyond it */
+			if (buf_pos >= count - 1 - tot_len)
+				break;
+
+			/* Format the register */
+			snprintf(buf + buf_pos, count - buf_pos, "%.*x: ",
+				 reg_len, i);
+			buf_pos += reg_len + 2;
+
+			/* Format the value, write all X if we can't read */
+			ret = regmap_read(map, i, &val);
+			if (ret == 0)
+				snprintf(buf + buf_pos, count - buf_pos,
+					 "%.*x", val_len, val);
+			else
+				memset(buf + buf_pos, 'X', val_len);
+			buf_pos += 2 * map->format.val_bytes;
+
+			buf[buf_pos++] = '\n';
+		}
+		p += tot_len;
+	}
+
+	ret = buf_pos;
+
+	if (copy_to_user(user_buf, buf, buf_pos)) {
+		ret = -EFAULT;
+		goto out;
+	}
+
+	*ppos += buf_pos;
+
+out:
+	kfree(buf);
+	return ret;
+}
+
+static const struct file_operations regmap_map_fops = {
+	.open = regmap_map_open_file,
+	.read = regmap_map_read_file,
+	.llseek = default_llseek,
+};
+
+
+void regmap_debugfs_init(struct regmap *map)
+{
+	map->debugfs = debugfs_create_dir(dev_name(map->dev),
+					  regmap_debugfs_root);
+	if (!map->debugfs) {
+		dev_warn(map->dev, "Failed to create debugfs directory\n");
+		return;
+	}
+
+	if (map->max_register)
+		debugfs_create_file("registers", 0400, map->debugfs,
+				    map, &regmap_map_fops);
+}
+
+void regmap_debugfs_exit(struct regmap *map)
+{
+	debugfs_remove_recursive(map->debugfs);
+}
+
+void regmap_debugfs_initcall(void)
+{
+	regmap_debugfs_root = debugfs_create_dir("regmap", NULL);
+	if (!regmap_debugfs_root) {
+		pr_warn("regmap: Failed to create debugfs root\n");
+		return;
+	}
+}

drivers/base/regmap/regmap.c

@@ -156,6 +156,8 @@ struct regmap *regmap_init(struct device *dev,
 		goto err_bus;
 	}
 
+	regmap_debugfs_init(map);
+
 	return map;
 
 err_bus:
@@ -172,6 +174,7 @@ EXPORT_SYMBOL_GPL(regmap_init);
  */
 void regmap_exit(struct regmap *map)
 {
+	regmap_debugfs_exit(map);
 	kfree(map->work_buf);
 	module_put(map->bus->owner);
 	kfree(map);
@@ -472,3 +475,11 @@ int regmap_update_bits(struct regmap *map, unsigned int reg,
 	return ret;
 }
 EXPORT_SYMBOL_GPL(regmap_update_bits);
+
+static int __init regmap_initcall(void)
+{
+	regmap_debugfs_initcall();
+
+	return 0;
+}
+postcore_initcall(regmap_initcall);