Commit cdf01e08 authored by Nuno Sa's avatar Nuno Sa Committed by Jonathan Cameron
Browse files

iio: backend: add debugFs interface 



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: default avatarNuno Sa <nuno.sa@analog.com>
Link: https://patch.msgid.link/20240802-dev-iio-backend-add-debugfs-v2-2-4cb62852f0d0@analog.com


Signed-off-by: default avatarJonathan Cameron <Jonathan.Cameron@huawei.com>
parent 2256f37e

Documentation/ABI/testing/debugfs-iio-backend

0 → 100644
+20 −0
Original line number Diff line number Diff line 
What:		/sys/kernel/debug/iio/iio:deviceX/backendY/name

KernelVersion:	6.11

Contact:	linux-iio@vger.kernel.org

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@vger.kernel.org

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

MAINTAINERS

+1 −0
Original line number Diff line number Diff line
@@ -10894,6 +10894,7 @@ M: Nuno Sa <nuno.sa@analog.com> 
R:	Olivier Moysan <olivier.moysan@foss.st.com>

L:	linux-iio@vger.kernel.org

S:	Maintained

F:	Documentation/ABI/testing/debugfs-iio-backend

F:	drivers/iio/industrialio-backend.c

F:	include/linux/iio/backend.h
































drivers/iio/industrialio-backend.c



+145
−0






























Original line number
Diff line number
Diff line







@@ -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;
































include/linux/iio/backend.h



+14
−0






























Original line number
Diff line number
Diff line







@@ -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