From: Nuno Sa <nuno.sa@xxxxxxxxxx>
This adds a basic debugfs interface for backends. Two new ops are being
added:
* debugfs_reg_access: Analogous to the core IIO one but for backend
devices.
* debugfs_print_chan_status: One useful usecase for this one is for
testing test tones in a digital interface and "ask" the backend to
dump more details on why a test tone might have errors.
Signed-off-by: Nuno Sa <nuno.sa@xxxxxxxxxx>
---
Documentation/ABI/testing/debugfs-iio-backend | 20 ++++
MAINTAINERS | 1 +
drivers/iio/industrialio-backend.c | 145 ++++++++++++++++++++++++++
include/linux/iio/backend.h | 14 +++
4 files changed, 180 insertions(+)
diff --git a/Documentation/ABI/testing/debugfs-iio-backend b/Documentation/ABI/testing/debugfs-iio-backend
new file mode 100644
index 000000000000..01ab94469432
--- /dev/null
+++ b/Documentation/ABI/testing/debugfs-iio-backend
@@ -0,0 +1,20 @@
+What: /sys/kernel/debug/iio/iio:deviceX/backendY/name
+KernelVersion: 6.11
+Contact: linux-iio@xxxxxxxxxxxxxxx
+Description:
+ Name of Backend Y connected to device X.
+
+What: /sys/kernel/debug/iio/iio:deviceX/backendY/direct_reg_access
+KernelVersion: 6.11
+Contact: linux-iio@xxxxxxxxxxxxxxx
+Description:
+ Directly access the registers of backend Y. Typical usage is:
+
+ Reading address 0x50
+ echo 0x50 > direct_reg_access
+ cat direct_reg_access
+
+ Writing address 0x50
+ echo 0x50 0x3 > direct_reg_access
+ //readback address 0x50
+ cat direct_reg_access
diff --git a/MAINTAINERS b/MAINTAINERS
index cd677bcc54da..c28bcbc94725 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -10885,6 +10885,7 @@ M: Nuno Sa <nuno.sa@xxxxxxxxxx>
R: Olivier Moysan <olivier.moysan@xxxxxxxxxxx>
L: linux-iio@xxxxxxxxxxxxxxx
S: Maintained
+F: Documentation/ABI/testing/debugfs-iio-backend
F: drivers/iio/industrialio-backend.c
F: include/linux/iio/backend.h
diff --git a/drivers/iio/industrialio-backend.c b/drivers/iio/industrialio-backend.c
index 0cf80ffd2e61..468eadeaf23d 100644
--- a/drivers/iio/industrialio-backend.c
+++ b/drivers/iio/industrialio-backend.c
@@ -32,6 +32,7 @@
#define dev_fmt(fmt) "iio-backend: " fmt
#include <linux/cleanup.h>
+#include <linux/debugfs.h>
#include <linux/device.h>
#include <linux/err.h>
#include <linux/errno.h>
@@ -53,6 +54,14 @@ struct iio_backend {
struct device *dev;
struct module *owner;
void *priv;
+ const char *name;
+ unsigned int cached_reg_addr;
+ /*
+ * This index is relative to the frontend. Meaning that for
+ * frontends with multiple backends, this will be the index of this
+ * backend. Used for the debugfs directory name.
+ */
+ u8 idx;
};
/*
@@ -117,6 +126,138 @@ static DEFINE_MUTEX(iio_back_lock);
__stringify(op)); \
}
+static ssize_t iio_backend_debugfs_read_reg(struct file *file,
+ char __user *userbuf,
+ size_t count, loff_t *ppos)
+{
+ struct iio_backend *back = file->private_data;
+ char read_buf[20];
+ unsigned int val;
+ int ret, len;
+
+ ret = iio_backend_op_call(back, debugfs_reg_access,
+ back->cached_reg_addr, 0, &val);
+ if (ret)
+ return ret;
+
+ len = scnprintf(read_buf, sizeof(read_buf), "0x%X\n", val);
+
+ return simple_read_from_buffer(userbuf, count, ppos, read_buf, len);
+}
+
+static ssize_t iio_backend_debugfs_write_reg(struct file *file,
+ const char __user *userbuf,
+ size_t count, loff_t *ppos)
+{
+ struct iio_backend *back = file->private_data;
+ unsigned int val;
+ char buf[80];
+ ssize_t rc;
+ int ret;
+
+ rc = simple_write_to_buffer(buf, sizeof(buf), ppos, userbuf, count);
+ if (rc < 0)
+ return rc;
+
+ ret = sscanf(buf, "%i %i", &back->cached_reg_addr, &val);
+
+ switch (ret) {
+ case 1:
+ return count;
+ case 2:
+ ret = iio_backend_op_call(back, debugfs_reg_access,
+ back->cached_reg_addr, val, NULL);
+ if (ret)
+ return ret;
+ return count;
+ default:
+ return -EINVAL;
+ }
+}
+
+static const struct file_operations iio_backend_debugfs_reg_fops = {
+ .open = simple_open,
+ .read = iio_backend_debugfs_read_reg,
+ .write = iio_backend_debugfs_write_reg,
+};
+
+static ssize_t iio_backend_debugfs_read_name(struct file *file,
+ char __user *userbuf,
+ size_t count, loff_t *ppos)
+{
+ struct iio_backend *back = file->private_data;
+ char name[128];
+ int len;
+
+ len = scnprintf(name, sizeof(name), "%s\n", back->name);
+
+ return simple_read_from_buffer(userbuf, count, ppos, name, len);
+}
+
+static const struct file_operations iio_backend_debugfs_name_fops = {
+ .open = simple_open,
+ .read = iio_backend_debugfs_read_name,
+};
+
+/**
+ * iio_backend_debugfs_add - Add debugfs interfaces for Backends
+ * @back: Backend device
+ * @indio_dev: IIO device
+ */
+void iio_backend_debugfs_add(struct iio_backend *back,
+ struct iio_dev *indio_dev)
+{
+ struct dentry *d = iio_get_debugfs_dentry(indio_dev);
+ struct dentry *back_d;
+ char name[128];
+
+ if (!IS_ENABLED(CONFIG_DEBUG_FS) || !d)
+ return;
+ if (!back->ops->debugfs_reg_access && !back->name)
+ return;
+
+ snprintf(name, sizeof(name), "backend%d", back->idx);
+
+ back_d = debugfs_create_dir(name, d);
+ if (!back_d)
+ return;
+
+ if (back->ops->debugfs_reg_access)
+ debugfs_create_file("direct_reg_access", 0600, back_d, back,
+ &iio_backend_debugfs_reg_fops);
+
+ if (back->name)
+ debugfs_create_file("name", 0400, back_d, back,
+ &iio_backend_debugfs_name_fops);
+}
+EXPORT_SYMBOL_NS_GPL(iio_backend_debugfs_add, IIO_BACKEND);
+
+/**
+ * iio_backend_debugfs_print_chan_status - Print channel status
+ * @back: Backend device
+ * @chan: Channel number
+ * @buf: Buffer where to print the status
+ * @len: Available space
+ *
+ * One usecase where this is useful is for testing test tones in a digital
+ * interface and "ask" the backend to dump more details on why a test tone might
+ * have errors.
+ *
+ * RETURNS:
+ * Number of copied bytes on success, negative error code on failure.
+ */
+ssize_t iio_backend_debugfs_print_chan_status(struct iio_backend *back,
+ unsigned int chan, char *buf,
+ size_t len)
+{
+ if (!IS_ENABLED(CONFIG_DEBUG_FS))
+ return -ENODEV;
+
+ return iio_backend_op_call(back, debugfs_print_chan_status, chan, buf,
+ len);
+}
+EXPORT_SYMBOL_NS_GPL(iio_backend_debugfs_print_chan_status, IIO_BACKEND);
+
/**
* iio_backend_chan_enable - Enable a backend channel
* @back: Backend device
@@ -577,6 +718,9 @@ struct iio_backend *devm_iio_backend_get(struct device *dev, const char *name)
if (ret)
return ERR_PTR(ret);
+ if (name)
+ back->idx = index;
+
return back;
}
@@ -668,6 +812,7 @@ int devm_iio_backend_register(struct device *dev,
return -ENOMEM;
back->ops = info->ops;
+ back->name = info->name;
back->owner = dev->driver->owner;
back->dev = dev;
back->priv = priv;
diff --git a/include/linux/iio/backend.h b/include/linux/iio/backend.h
index f120fa2e0a43..9d0dba7ab9e7 100644
--- a/include/linux/iio/backend.h
+++ b/include/linux/iio/backend.h
@@ -22,6 +22,8 @@ enum iio_backend_data_source {
IIO_BACKEND_DATA_SOURCE_MAX
};
+#define iio_backend_debugfs_ptr(ptr) PTR_IF(IS_ENABLED(CONFIG_DEBUG_FS), ptr)
+
/**
* IIO_BACKEND_EX_INFO - Helper for an IIO extended channel attribute
* @_name: Attribute name
@@ -81,6 +83,8 @@ enum iio_backend_sample_trigger {
* @extend_chan_spec: Extend an IIO channel.
* @ext_info_set: Extended info setter.
* @ext_info_get: Extended info getter.
+ * @debugfs_print_chan_status: Print channel status into a buffer.
+ * @debugfs_reg_access: Read or write register value of backend.
**/
struct iio_backend_ops {
int (*enable)(struct iio_backend *back);
@@ -113,6 +117,11 @@ struct iio_backend_ops {
const char *buf, size_t len);
int (*ext_info_get)(struct iio_backend *back, uintptr_t private,
const struct iio_chan_spec *chan, char *buf);
+ int (*debugfs_print_chan_status)(struct iio_backend *back,
+ unsigned int chan, char *buf,
+ size_t len);
+ int (*debugfs_reg_access)(struct iio_backend *back, unsigned int reg,
+ unsigned int writeval, unsigned int *readval);
};
/**
@@ -163,4 +172,9 @@ __devm_iio_backend_get_from_fwnode_lookup(struct device *dev,
int devm_iio_backend_register(struct device *dev,
const struct iio_backend_info *info, void *priv);
+ssize_t iio_backend_debugfs_print_chan_status(struct iio_backend *back,
+ unsigned int chan, char *buf,
+ size_t len);
+void iio_backend_debugfs_add(struct iio_backend *back,
+ struct iio_dev *indio_dev);
#endif
--
2.45.2
