1 files changed, 127 insertions, 12 deletions

diff --git a/include/linux/iio/iio.h b/include/linux/iio/iio.h
index 872ebdf0dd77..a9ecff191bd9 100644
--- a/include/linux/iio/iio.h
+++ b/include/linux/iio/iio.h
@@ -10,6 +10,7 @@
 #include <linux/align.h>
 #include <linux/device.h>
 #include <linux/cdev.h>
+#include <linux/cleanup.h>
 #include <linux/compiler_types.h>
 #include <linux/minmax.h>
 #include <linux/slab.h>
@@ -661,34 +662,148 @@ void iio_device_unregister(struct iio_dev *indio_dev);
 int __devm_iio_device_register(struct device *dev, struct iio_dev *indio_dev,
 			       struct module *this_mod);
 int iio_push_event(struct iio_dev *indio_dev, u64 ev_code, s64 timestamp);
-bool __iio_device_claim_direct(struct iio_dev *indio_dev);
-void __iio_device_release_direct(struct iio_dev *indio_dev);
+
+void __iio_dev_mode_lock(struct iio_dev *indio_dev) __acquires(indio_dev);
+void __iio_dev_mode_unlock(struct iio_dev *indio_dev) __releases(indio_dev);
 
 /*
  * Helper functions that allow claim and release of direct mode
  * in a fashion that doesn't generate many false positives from sparse.
  * Note this must remain static inline in the header so that sparse
- * can see the __acquire() marking. Revisit when sparse supports
- * __cond_acquires()
+ * can see the __acquires() and __releases() annotations.
+ */
+
+/**
+ * iio_device_claim_direct() - Keep device in direct mode
+ * @indio_dev:	the iio_dev associated with the device
+ *
+ * If the device is in direct mode it is guaranteed to stay
+ * that way until iio_device_release_direct() is called.
+ *
+ * Use with iio_device_release_direct().
+ *
+ * Returns: true on success, false on failure.
  */
 static inline bool iio_device_claim_direct(struct iio_dev *indio_dev)
 {
-	if (!__iio_device_claim_direct(indio_dev))
-		return false;
+	__iio_dev_mode_lock(indio_dev);
 
-	__acquire(iio_dev);
+	if (iio_buffer_enabled(indio_dev)) {
+		__iio_dev_mode_unlock(indio_dev);
+		return false;
+	}
 
 	return true;
 }
 
-static inline void iio_device_release_direct(struct iio_dev *indio_dev)
+/**
+ * iio_device_release_direct() - Releases claim on direct mode
+ * @indio_dev:	the iio_dev associated with the device
+ *
+ * Release the claim. Device is no longer guaranteed to stay
+ * in direct mode.
+ *
+ * Use with iio_device_claim_direct().
+ */
+#define iio_device_release_direct(indio_dev) __iio_dev_mode_unlock(indio_dev)
+
+/**
+ * iio_device_try_claim_buffer_mode() - Keep device in buffer mode
+ * @indio_dev:	the iio_dev associated with the device
+ *
+ * If the device is in buffer mode it is guaranteed to stay
+ * that way until iio_device_release_buffer_mode() is called.
+ *
+ * Use with iio_device_release_buffer_mode().
+ *
+ * Returns: true on success, false on failure.
+ */
+static inline bool iio_device_try_claim_buffer_mode(struct iio_dev *indio_dev)
 {
-	__iio_device_release_direct(indio_dev);
-	__release(indio_dev);
+	__iio_dev_mode_lock(indio_dev);
+
+	if (!iio_buffer_enabled(indio_dev)) {
+		__iio_dev_mode_unlock(indio_dev);
+		return false;
+	}
+
+	return true;
 }
 
-int iio_device_claim_buffer_mode(struct iio_dev *indio_dev);
-void iio_device_release_buffer_mode(struct iio_dev *indio_dev);
+/**
+ * iio_device_release_buffer_mode() - releases claim on buffer mode
+ * @indio_dev:	the iio_dev associated with the device
+ *
+ * Release the claim. Device is no longer guaranteed to stay
+ * in buffer mode.
+ *
+ * Use with iio_device_try_claim_buffer_mode().
+ */
+#define iio_device_release_buffer_mode(indio_dev) __iio_dev_mode_unlock(indio_dev)
+
+/*
+ * These classes are not meant to be used directly by drivers (hence the
+ * __priv__ prefix). Instead, documented wrapper macros are provided below to
+ * enforce the use of ACQUIRE() or guard() semantics and avoid the problematic
+ * scoped guard variants.
+ */
+DEFINE_GUARD(__priv__iio_dev_mode_lock, struct iio_dev *,
+	     __iio_dev_mode_lock(_T), __iio_dev_mode_unlock(_T));
+DEFINE_GUARD_COND(__priv__iio_dev_mode_lock, _try_direct,
+		  iio_device_claim_direct(_T));
+
+/**
+ * IIO_DEV_ACQUIRE_DIRECT_MODE() - Tries to acquire the direct mode lock with
+ *				   automatic release
+ * @dev: IIO device instance
+ * @claim: Variable identifier to store acquire result
+ *
+ * Tries to acquire the direct mode lock with cleanup ACQUIRE() semantics and
+ * automatically releases it at the end of the scope. It most be always paired
+ * with IIO_DEV_ACQUIRE_ERR(), for example (notice the scope braces)::
+ *
+ *	switch() {
+ *	case IIO_CHAN_INFO_RAW: {
+ *		IIO_DEV_ACQUIRE_DIRECT_MODE(indio_dev, claim);
+ *		if (IIO_DEV_ACQUIRE_FAILED(claim))
+ *			return -EBUSY;
+ *
+ *		...
+ *	}
+ *	case IIO_CHAN_INFO_SCALE:
+ *		...
+ *	...
+ *	}
+ *
+ * Context: Can sleep
+ */
+#define IIO_DEV_ACQUIRE_DIRECT_MODE(dev, claim) \
+	ACQUIRE(__priv__iio_dev_mode_lock_try_direct, claim)(dev)
+
+/**
+ * IIO_DEV_ACQUIRE_FAILED() - ACQUIRE_ERR() wrapper
+ * @claim: The claim variable passed to IIO_DEV_ACQUIRE_*_MODE()
+ *
+ * Return: true if failed to acquire the mode, otherwise false.
+ */
+#define IIO_DEV_ACQUIRE_FAILED(claim) \
+	ACQUIRE_ERR(__priv__iio_dev_mode_lock_try_direct, &(claim))
+
+/**
+ * IIO_DEV_GUARD_CURRENT_MODE() - Acquires the mode lock with automatic release
+ * @dev: IIO device instance
+ *
+ * Acquires the mode lock with cleanup guard() semantics. It is usually paired
+ * with iio_buffer_enabled().
+ *
+ * This should *not* be used to protect internal driver state and it's use in
+ * general is *strongly* discouraged. Use any of the IIO_DEV_ACQUIRE_*_MODE()
+ * variants.
+ *
+ * Context: Can sleep
+ */
+#define IIO_DEV_GUARD_CURRENT_MODE(dev) \
+	guard(__priv__iio_dev_mode_lock)(dev)
 
 extern const struct bus_type iio_bus_type;