1 files changed, 194 insertions, 31 deletions

diff --git a/include/linux/iio/iio.h b/include/linux/iio/iio.h
index 56161e02f002..2c91b7659ce9 100644
--- a/include/linux/iio/iio.h
+++ b/include/linux/iio/iio.h
@@ -7,9 +7,12 @@
 #ifndef _INDUSTRIAL_IO_H_
 #define _INDUSTRIAL_IO_H_
 
+#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>
 #include <linux/iio/types.h>
 /* IIO TODO LIST */
@@ -269,14 +272,14 @@ struct iio_chan_spec {
 			unsigned int num_ext_scan_type;
 		};
 	};
-	long			info_mask_separate;
-	long			info_mask_separate_available;
-	long			info_mask_shared_by_type;
-	long			info_mask_shared_by_type_available;
-	long			info_mask_shared_by_dir;
-	long			info_mask_shared_by_dir_available;
-	long			info_mask_shared_by_all;
-	long			info_mask_shared_by_all_available;
+	unsigned long			info_mask_separate;
+	unsigned long			info_mask_separate_available;
+	unsigned long			info_mask_shared_by_type;
+	unsigned long			info_mask_shared_by_type_available;
+	unsigned long			info_mask_shared_by_dir;
+	unsigned long			info_mask_shared_by_dir_available;
+	unsigned long			info_mask_shared_by_all;
+	unsigned long			info_mask_shared_by_all_available;
 	const struct iio_event_spec *event_spec;
 	unsigned int		num_event_specs;
 	const struct iio_chan_spec_ext_info *ext_info;
@@ -659,37 +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);
-int iio_device_claim_direct_mode(struct iio_dev *indio_dev);
-void iio_device_release_direct_mode(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);
 
 /*
- * This autocleanup logic is normally used via
- * iio_device_claim_direct_scoped().
+ * 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 __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)
+{
+	__iio_dev_mode_lock(indio_dev);
+
+	if (iio_buffer_enabled(indio_dev)) {
+		__iio_dev_mode_unlock(indio_dev);
+		return false;
+	}
+
+	return true;
+}
+
+/**
+ * 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_dev_mode_lock(indio_dev);
+
+	if (!iio_buffer_enabled(indio_dev)) {
+		__iio_dev_mode_unlock(indio_dev);
+		return false;
+	}
+
+	return true;
+}
+
+/**
+ * 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_GUARD(iio_claim_direct, struct iio_dev *, iio_device_claim_direct_mode(_T),
-	     iio_device_release_direct_mode(_T))
+#define iio_device_release_buffer_mode(indio_dev) __iio_dev_mode_unlock(indio_dev)
 
-DEFINE_GUARD_COND(iio_claim_direct, _try, ({
-			struct iio_dev *dev;
-			int d = iio_device_claim_direct_mode(_T);
+/*
+ * 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));
 
-			if (d < 0)
-				dev = NULL;
-			else
-				dev = _T;
-			dev;
-		}))
+/**
+ * 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_device_claim_direct_scoped() - Scoped call to iio_device_claim_direct.
- * @fail: What to do on failure to claim device.
- * @iio_dev: Pointer to the IIO devices structure
+ * 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_device_claim_direct_scoped(fail, iio_dev) \
-	scoped_cond_guard(iio_claim_direct_try, fail, iio_dev)
+#define IIO_DEV_ACQUIRE_FAILED(claim) \
+	ACQUIRE_ERR(__priv__iio_dev_mode_lock_try_direct, &(claim))
 
-int iio_device_claim_buffer_mode(struct iio_dev *indio_dev);
-void iio_device_release_buffer_mode(struct iio_dev *indio_dev);
+/**
+ * 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;
 
@@ -778,8 +892,57 @@ static inline void *iio_device_get_drvdata(const struct iio_dev *indio_dev)
  * to in turn include IIO_DMA_MINALIGN'd elements such as buffers which
  * must not share  cachelines with the rest of the structure, thus making
  * them safe for use with non-coherent DMA.
+ *
+ * A number of drivers also use this on buffers that include a 64-bit timestamp
+ * that is used with iio_push_to_buffers_with_ts(). Therefore, in the case where
+ * DMA alignment is not sufficient for proper timestamp alignment, we align to
+ * 8 bytes instead.
+ */
+#define IIO_DMA_MINALIGN MAX(ARCH_DMA_MINALIGN, sizeof(s64))
+
+#define __IIO_DECLARE_BUFFER_WITH_TS(type, name, count) \
+	type name[ALIGN((count), sizeof(s64) / sizeof(type)) + sizeof(s64) / sizeof(type)]
+
+/**
+ * IIO_DECLARE_BUFFER_WITH_TS() - Declare a buffer with timestamp
+ * @type: element type of the buffer
+ * @name: identifier name of the buffer
+ * @count: number of elements in the buffer
+ *
+ * Declares a buffer that is safe to use with iio_push_to_buffers_with_ts(). In
+ * addition to allocating enough space for @count elements of @type, it also
+ * allocates space for a s64 timestamp at the end of the buffer and ensures
+ * proper alignment of the timestamp.
  */
-#define IIO_DMA_MINALIGN ARCH_DMA_MINALIGN
+#define IIO_DECLARE_BUFFER_WITH_TS(type, name, count) \
+	__IIO_DECLARE_BUFFER_WITH_TS(type, name, count) __aligned(sizeof(s64))
+
+/**
+ * IIO_DECLARE_DMA_BUFFER_WITH_TS() - Declare a DMA-aligned buffer with timestamp
+ * @type: element type of the buffer
+ * @name: identifier name of the buffer
+ * @count: number of elements in the buffer
+ *
+ * Same as IIO_DECLARE_BUFFER_WITH_TS(), but is uses __aligned(IIO_DMA_MINALIGN)
+ * to ensure that the buffer doesn't share cachelines with anything that comes
+ * before it in a struct. This should not be used for stack-allocated buffers
+ * as stack memory cannot generally be used for DMA.
+ */
+#define IIO_DECLARE_DMA_BUFFER_WITH_TS(type, name, count) \
+	__IIO_DECLARE_BUFFER_WITH_TS(type, name, count) __aligned(IIO_DMA_MINALIGN)
+
+/**
+ * IIO_DECLARE_QUATERNION() - Declare a quaternion element
+ * @type: element type of the individual vectors
+ * @name: identifier name
+ *
+ * Quaternions are a vector composed of 4 elements (W, X, Y, Z). Use this macro
+ * to declare a quaternion element in a struct to ensure proper alignment in
+ * an IIO buffer.
+ */
+#define IIO_DECLARE_QUATERNION(type, name) \
+	type name[4] __aligned(sizeof(type) * 4)
+
 struct iio_dev *iio_device_alloc(struct device *parent, int sizeof_priv);
 
 /* The information at the returned address is guaranteed to be cacheline aligned */