[PATCH 2/4] iio: core: Introduce debugfs support, add support for direct register access

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From: Michael Hennerich <michael.hennerich@xxxxxxxxxx>

Signed-off-by: Michael Hennerich <michael.hennerich@xxxxxxxxxx>
---
 drivers/staging/iio/iio.h               |    5 +
 drivers/staging/iio/industrialio-core.c |  124 ++++++++++++++++++++++++++++++-
 2 files changed, 128 insertions(+), 1 deletions(-)

diff --git a/drivers/staging/iio/iio.h b/drivers/staging/iio/iio.h
index 42a362c..d0cf71f 100644
--- a/drivers/staging/iio/iio.h
+++ b/drivers/staging/iio/iio.h
@@ -269,6 +269,9 @@ struct iio_info {
 				struct iio_trigger *trig);
 	int (*update_scan_mode)(struct iio_dev *indio_dev,
 				const unsigned long *scan_mask);
+	int (*debugfs_reg_access)(struct iio_dev *indio_dev,
+				  unsigned reg, unsigned writeval,
+				  unsigned *readval);
 };
 
 /**
@@ -347,6 +350,8 @@ struct iio_dev {
 	int				groupcounter;
 
 	unsigned long			flags;
+	struct dentry			*debugfs_dentry;
+	unsigned			cached_reg_addr;
 };
 
 /**
diff --git a/drivers/staging/iio/industrialio-core.c b/drivers/staging/iio/industrialio-core.c
index e4824fe..cf48489 100644
--- a/drivers/staging/iio/industrialio-core.c
+++ b/drivers/staging/iio/industrialio-core.c
@@ -22,6 +22,7 @@
 #include <linux/cdev.h>
 #include <linux/slab.h>
 #include <linux/anon_inodes.h>
+#include <linux/debugfs.h>
 #include "iio.h"
 #include "iio_core.h"
 #include "iio_core_trigger.h"
@@ -39,6 +40,8 @@ struct bus_type iio_bus_type = {
 };
 EXPORT_SYMBOL(iio_bus_type);
 
+static struct dentry *iio_debugfs_dentry;
+
 static const char * const iio_data_type_name[] = {
 	[IIO_RAW] = "raw",
 	[IIO_PROCESSED] = "input",
@@ -129,6 +132,8 @@ static int __init iio_init(void)
 		goto error_unregister_bus_type;
 	}
 
+	iio_debugfs_dentry = debugfs_create_dir("iio", NULL);
+
 	return 0;
 
 error_unregister_bus_type:
@@ -142,6 +147,114 @@ static void __exit iio_exit(void)
 	if (iio_devt)
 		unregister_chrdev_region(iio_devt, IIO_DEV_MAX);
 	bus_unregister(&iio_bus_type);
+	debugfs_remove_recursive(iio_debugfs_dentry);
+}
+
+static int iio_debugfs_open(struct inode *inode, struct file *file)
+{
+	if (inode->i_private)
+		file->private_data = inode->i_private;
+
+	return 0;
+}
+
+static ssize_t iio_debugfs_read_reg(struct file *file, char __user *userbuf,
+			      size_t count, loff_t *ppos)
+{
+	struct iio_dev *indio_dev = file->private_data;
+	char buf[80], *p = buf;
+	unsigned val;
+	int ret;
+
+	ret = indio_dev->info->debugfs_reg_access(indio_dev,
+						  indio_dev->cached_reg_addr,
+						  0, &val);
+	if (ret)
+		dev_err(indio_dev->dev.parent, "%s: read failed\n", __func__);
+
+	p += sprintf(p, "0x%X\n", val);
+
+	return simple_read_from_buffer(userbuf, count, ppos, buf, p - buf);
+}
+
+static ssize_t iio_debugfs_write_reg(struct file *file,
+		     const char __user *userbuf, size_t count, loff_t *ppos)
+{
+	struct iio_dev *indio_dev = file->private_data;
+	unsigned reg, val;
+	char buf[80], *p = buf;
+	int ret;
+
+	count = min_t(size_t, count, (sizeof(buf)-1));
+	if (copy_from_user(p, userbuf, count))
+		return -EFAULT;
+
+	ret = sscanf(p, "%x %x", &reg, &val);
+
+	switch (ret) {
+	case 1:
+		indio_dev->cached_reg_addr = reg;
+		break;
+	case 2:
+		indio_dev->cached_reg_addr = reg;
+		ret = indio_dev->info->debugfs_reg_access(indio_dev, reg,
+							  val, NULL);
+		if (ret) {
+			dev_err(indio_dev->dev.parent, "%s: write failed\n",
+				__func__);
+			return ret;
+		}
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	return count;
+}
+
+static const struct file_operations iio_debugfs_reg_fops = {
+	.open = iio_debugfs_open,
+	.read = iio_debugfs_read_reg,
+	.write = iio_debugfs_write_reg,
+};
+
+static void iio_device_unregister_debugfs(struct iio_dev *indio_dev)
+{
+	debugfs_remove_recursive(indio_dev->debugfs_dentry);
+}
+
+static int iio_device_register_debugfs(struct iio_dev *indio_dev)
+{
+	struct dentry *d;
+
+	if (indio_dev->info->debugfs_reg_access == NULL)
+		return 0;
+
+	if (IS_ERR(iio_debugfs_dentry))
+		return 0;
+
+	indio_dev->debugfs_dentry =
+		debugfs_create_dir(dev_name(&indio_dev->dev),
+				   iio_debugfs_dentry);
+	if (IS_ERR(indio_dev->debugfs_dentry))
+		return IS_ERR(indio_dev->debugfs_dentry);
+
+	if (indio_dev->debugfs_dentry == NULL) {
+		dev_warn(indio_dev->dev.parent,
+			 "Failed to create debugfs directory\n");
+		return -EFAULT;
+
+	}
+
+	d = debugfs_create_file("direct_reg_access", 0644,
+				indio_dev->debugfs_dentry,
+				indio_dev, &iio_debugfs_reg_fops);
+	if (!d) {
+		iio_device_unregister_debugfs(indio_dev);
+		return -ENOMEM;
+	}
+
+	return 0;
 }
 
 static ssize_t iio_read_channel_info(struct device *dev,
@@ -565,6 +678,7 @@ static void iio_dev_release(struct device *device)
 		iio_device_unregister_trigger_consumer(indio_dev);
 	iio_device_unregister_eventset(indio_dev);
 	iio_device_unregister_sysfs(indio_dev);
+	iio_device_unregister_debugfs(indio_dev);
 }
 
 static struct device_type iio_dev_type = {
@@ -680,11 +794,17 @@ int iio_device_register(struct iio_dev *indio_dev)
 	/* configure elements for the chrdev */
 	indio_dev->dev.devt = MKDEV(MAJOR(iio_devt), indio_dev->id);
 
+	ret = iio_device_register_debugfs(indio_dev);
+	if (ret) {
+		dev_err(indio_dev->dev.parent,
+			"Failed to register debugfs interfaces\n");
+		goto error_ret;
+	}
 	ret = iio_device_register_sysfs(indio_dev);
 	if (ret) {
 		dev_err(indio_dev->dev.parent,
 			"Failed to register sysfs interfaces\n");
-		goto error_ret;
+		goto error_unreg_debugfs;
 	}
 	ret = iio_device_register_eventset(indio_dev);
 	if (ret) {
@@ -711,6 +831,8 @@ error_unreg_eventset:
 	iio_device_unregister_eventset(indio_dev);
 error_free_sysfs:
 	iio_device_unregister_sysfs(indio_dev);
+error_unreg_debugfs:
+	iio_device_unregister_debugfs(indio_dev);
 error_ret:
 	return ret;
 }
-- 
1.7.0.4


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