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>
---
drivers/iio/industrialio-backend.c | 115 +++++++++++++++++++++++++++++++++++++
include/linux/iio/backend.h | 16 +++++-
2 files changed, 130 insertions(+), 1 deletion(-)
diff --git a/drivers/iio/industrialio-backend.c b/drivers/iio/industrialio-backend.c
index f9da635cdfea..52cbde0d5885 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>
@@ -46,6 +47,8 @@
#include <linux/iio/backend.h>
#include <linux/iio/iio.h>
+#define IIO_BACKEND_DEFAULT_NAME "backend"
+
struct iio_backend {
struct list_head entry;
const struct iio_backend_ops *ops;
@@ -53,6 +56,8 @@ struct iio_backend {
struct device *dev;
struct module *owner;
void *priv;
+ const char *name;
+ unsigned int cached_reg_addr;
};
/*
@@ -117,6 +122,111 @@ 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,
+};
+
+/**
+ * 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);
+ char attr_name[128];
+
+ if (!IS_ENABLED(CONFIG_DEBUG_FS))
+ return;
+ if (!back->ops->debugfs_reg_access || !d)
+ return;
+
+ snprintf(attr_name, sizeof(attr_name), "%s_direct_reg_access",
+ back->name);
+
+ debugfs_create_file(attr_name, 0644, d, back,
+ &iio_backend_debugfs_reg_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 +687,11 @@ struct iio_backend *devm_iio_backend_get(struct device *dev, const char *name)
if (ret)
return ERR_PTR(ret);
+ if (name)
+ back->name = name;
+ else
+ back->name = IIO_BACKEND_DEFAULT_NAME;
+
return back;
}
diff --git a/include/linux/iio/backend.h b/include/linux/iio/backend.h
index 4e81931703ab..a643d86c7487 100644
--- a/include/linux/iio/backend.h
+++ b/include/linux/iio/backend.h
@@ -9,6 +9,7 @@ struct fwnode_handle;
struct iio_backend;
struct device;
struct iio_dev;
+struct dentry *d;
enum iio_backend_data_type {
IIO_BACKEND_TWOS_COMPLEMENT,
@@ -22,6 +23,8 @@ 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 +84,8 @@ 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 +118,11 @@ 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);
};
int iio_backend_chan_enable(struct iio_backend *back, unsigned int chan);
@@ -152,5 +162,9 @@ __devm_iio_backend_get_from_fwnode_lookup(struct device *dev,
int devm_iio_backend_register(struct device *dev,
const struct iio_backend_ops *ops, 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
