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From:   Li Chen <me@linux.beauty>
To:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        "Rafael J. Wysocki" <rafael@kernel.org>
Cc:     Li Chen <lchen@ambarella.com>, linux-kernel@vger.kernel.org
Subject: [PATCH v2] debugfs: allow to use regmap for print regs
Date:   Wed, 11 Jan 2023 15:21:29 +0800
Message-Id: <20230111072130.3885460-1-me@linux.beauty>
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From: Li Chen <lchen@ambarella.com>

Currently, debugfs_regset32 only contains void __iomem *base,
and it is not friendly to regmap user.

Let's add regmap to debugfs_regset32, and add debugfs_print_regmap_reg32
to allow debugfs_regset32_show handle regmap.

Signed-off-by: Li Chen <lchen@ambarella.com>
---
Changelog:

v1 -> v2:

Suggested by Greg, provide a new function for regmap instead of trying to overload old function.
---
 fs/debugfs/file.c       | 46 ++++++++++++++++++++++++++++++++++++++++-
 include/linux/debugfs.h | 10 +++++++++
 2 files changed, 55 insertions(+), 1 deletion(-)

diff --git a/fs/debugfs/file.c b/fs/debugfs/file.c
index b54f470e0d03..f204b27f757f 100644
--- a/fs/debugfs/file.c
+++ b/fs/debugfs/file.c
@@ -1137,14 +1137,58 @@ void debugfs_print_regs32(struct seq_file *s, const struct debugfs_reg32 *regs,
 }
 EXPORT_SYMBOL_GPL(debugfs_print_regs32);
 
+/**
+ * debugfs_print_regmap_regs32 - use seq_print to describe a set of registers
+ * @s: the seq_file structure being used to generate output
+ * @regs: an array if struct debugfs_reg32 structures
+ * @nregs: the length of the above array
+ * @regmap: regmap to be used in reading the registers
+ * @prefix: a string to be prefixed to every output line
+ *
+ * This function outputs a text block describing the current values of
+ * some 32-bit hardware registers. It is meant to be used within debugfs
+ * files based on seq_file that need to show registers, intermixed with other
+ * information. The prefix argument may be used to specify a leading string,
+ * because some peripherals have several blocks of identical registers,
+ * for example configuration of dma channels
+ */
+void debugfs_print_regmap_regs32(struct seq_file *s, const struct debugfs_reg32 *regs,
+			  int nregs, struct regmap *regmap, char *prefix)
+{
+	int i;
+	u32 val;
+
+	for (i = 0; i < nregs; i++, regs++) {
+		if (prefix)
+			seq_printf(s, "%s", prefix);
+		regmap_read(regmap, regs->offset, &val);
+		seq_printf(s, "%s = 0x%08x\n", regs->name, val);
+		if (seq_has_overflowed(s))
+			break;
+	}
+}
+EXPORT_SYMBOL_GPL(debugfs_print_regmap_regs32);
+
 static int debugfs_regset32_show(struct seq_file *s, void *data)
 {
 	struct debugfs_regset32 *regset = s->private;
+	void __iomem *base = regset->base;
+	struct regmap *regmap = regset->regmap;
+
+	if ((regmap && base) || (!regmap && !base)) {
+		seq_puts(
+			s,
+			"You should provide one and only one between base and regmap!\n");
+		return -EINVAL;
+	}
 
 	if (regset->dev)
 		pm_runtime_get_sync(regset->dev);
 
-	debugfs_print_regs32(s, regset->regs, regset->nregs, regset->base, "");
+	if (base)
+		debugfs_print_regs32(s, regset->regs, regset->nregs, base, "");
+	if (regmap)
+		debugfs_print_regmap_regs32(s, regset->regs, regset->nregs, regmap, "");
 
 	if (regset->dev)
 		pm_runtime_put(regset->dev);
diff --git a/include/linux/debugfs.h b/include/linux/debugfs.h
index ea2d919fd9c7..04bc2bb70b79 100644
--- a/include/linux/debugfs.h
+++ b/include/linux/debugfs.h
@@ -17,6 +17,7 @@
 
 #include <linux/types.h>
 #include <linux/compiler.h>
+#include <linux/regmap.h>
 
 struct device;
 struct file_operations;
@@ -35,6 +36,7 @@ struct debugfs_regset32 {
 	const struct debugfs_reg32 *regs;
 	int nregs;
 	void __iomem *base;
+	struct regmap *regmap;
 	struct device *dev;	/* Optional device for Runtime PM */
 };
 
@@ -152,6 +154,9 @@ void debugfs_create_regset32(const char *name, umode_t mode,
 void debugfs_print_regs32(struct seq_file *s, const struct debugfs_reg32 *regs,
 			  int nregs, void __iomem *base, char *prefix);
 
+void debugfs_print_regmap_regs32(struct seq_file *s, const struct debugfs_reg32 *regs,
+			  int nregs, struct regmap *regmap, char *prefix);
+
 void debugfs_create_u32_array(const char *name, umode_t mode,
 			      struct dentry *parent,
 			      struct debugfs_u32_array *array);
@@ -338,6 +343,11 @@ static inline void debugfs_print_regs32(struct seq_file *s, const struct debugfs
 {
 }
 
+static inline void debugfs_print_regmap_regs32(struct seq_file *s,
+					       const struct debugfs_reg32 *regs,
+					       int nregs, struct regmap *regmap,
+					       char *prefix);
+
 static inline bool debugfs_initialized(void)
 {
 	return false;
-- 
2.34.1