[PATCH 6.18 158/175] firmware: cs_dsp: Factor out common debugfs string read

Greg Kroah-Hartman
2026-02-09T14:33:59Z

From: Richard Fitzgerald <rf@opensource.cirrus.com>

[ Upstream commit 78cfd833bc04c0398ca4cfc64704350aebe4d4c2 ]

cs_dsp_debugfs_wmfw_read() and cs_dsp_debugfs_bin_read() were identical
except for which struct member they printed. Move all this duplicated
code into a common function cs_dsp_debugfs_string_read().

The check for dsp->booted has been removed because this is redundant.
The two strings are set when the DSP is booted and cleared when the
DSP is powered-down.

Access to the string char * must be protected by the pwr_lock mutex. The
string is passed into cs_dsp_debugfs_string_read() as a pointer to the
char * so that the mutex lock can also be factored out into
cs_dsp_debugfs_string_read().

wmfw_file_name and bin_file_name members of struct cs_dsp have been
changed to const char *. It makes for a better API to pass a const
pointer into cs_dsp_debugfs_string_read().

Signed-off-by: Richard Fitzgerald <rf@opensource.cirrus.com>
Link: https://patch.msgid.link/20251120130640.1169780-2-rf@opensource.cirrus.com
Signed-off-by: Mark Brown <broonie@kernel.org>
Stable-dep-of: 10db9f6899dd ("firmware: cs_dsp: rate-limit log messages in KUnit builds")
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/firmware/cirrus/cs_dsp.c | 45 ++++++++++++--------------
include/linux/firmware/cirrus/cs_dsp.h | 4 +--
2 files changed, 23 insertions(+), 26 deletions(-)

diff --git a/drivers/firmware/cirrus/cs_dsp.c b/drivers/firmware/cirrus/cs_dsp.c
index f51047d8ea64f..58e41751dbc19 100644
--- a/drivers/firmware/cirrus/cs_dsp.c
+++ b/drivers/firmware/cirrus/cs_dsp.c
@@ -9,6 +9,7 @@
* Cirrus Logic International Semiconductor Ltd.
*/

+#include <linux/cleanup.h>
#include <linux/ctype.h>
#include <linux/debugfs.h>
#include <linux/delay.h>
@@ -410,24 +411,30 @@ static void cs_dsp_debugfs_clear(struct cs_dsp *dsp)
dsp->bin_file_name = NULL;
}

+static ssize_t cs_dsp_debugfs_string_read(struct cs_dsp *dsp,
+ char __user *user_buf,
+ size_t count, loff_t *ppos,
+ const char **pstr)
+{
+ const char *str;
+
+ scoped_guard(mutex, &dsp->pwr_lock) {
+ str = *pstr;
+ if (!str)
+ return 0;
+
+ return simple_read_from_buffer(user_buf, count, ppos, str, strlen(str));
+ }
+}
+
static ssize_t cs_dsp_debugfs_wmfw_read(struct file *file,
char __user *user_buf,
size_t count, loff_t *ppos)
{
struct cs_dsp *dsp = file->private_data;
- ssize_t ret;

- mutex_lock(&dsp->pwr_lock);
-
- if (!dsp->wmfw_file_name || !dsp->booted)
- ret = 0;
- else
- ret = simple_read_from_buffer(user_buf, count, ppos,
- dsp->wmfw_file_name,
- strlen(dsp->wmfw_file_name));
-
- mutex_unlock(&dsp->pwr_lock);
- return ret;
+ return cs_dsp_debugfs_string_read(dsp, user_buf, count, ppos,
+ &dsp->wmfw_file_name);
}

static ssize_t cs_dsp_debugfs_bin_read(struct file *file,
@@ -435,19 +442,9 @@ static ssize_t cs_dsp_debugfs_bin_read(struct file *file,
size_t count, loff_t *ppos)
{
struct cs_dsp *dsp = file->private_data;
- ssize_t ret;
-
- mutex_lock(&dsp->pwr_lock);

- if (!dsp->bin_file_name || !dsp->booted)
- ret = 0;
- else
- ret = simple_read_from_buffer(user_buf, count, ppos,
- dsp->bin_file_name,
- strlen(dsp->bin_file_name));
-
- mutex_unlock(&dsp->pwr_lock);
- return ret;
+ return cs_dsp_debugfs_string_read(dsp, user_buf, count, ppos,
+ &dsp->bin_file_name);
}

static const struct {
diff --git a/include/linux/firmware/cirrus/cs_dsp.h b/include/linux/firmware/cirrus/cs_dsp.h
index a66eb7624730c..69959032f8f51 100644
--- a/include/linux/firmware/cirrus/cs_dsp.h
+++ b/include/linux/firmware/cirrus/cs_dsp.h
@@ -188,8 +188,8 @@ struct cs_dsp {

#ifdef CONFIG_DEBUG_FS
struct dentry *debugfs_root;
- char *wmfw_file_name;
- char *bin_file_name;
+ const char *wmfw_file_name;
+ const char *bin_file_name;
#endif
};

--
2.51.0