1 /* SPDX-License-Identifier: GPL-2.0 */ 2 #ifndef _IIO_BUFFER_GENERIC_IMPL_H_ 3 #define _IIO_BUFFER_GENERIC_IMPL_H_ 4 #include <linux/sysfs.h> 5 #include <linux/kref.h> 6 7 #ifdef CONFIG_IIO_BUFFER 8 9 #include <uapi/linux/iio/buffer.h> 10 11 struct iio_dev; 12 struct iio_buffer; 13 14 /** 15 * INDIO_BUFFER_FLAG_FIXED_WATERMARK - Watermark level of the buffer can not be 16 * configured. It has a fixed value which will be buffer specific. 17 */ 18 #define INDIO_BUFFER_FLAG_FIXED_WATERMARK BIT(0) 19 20 /** 21 * struct iio_buffer_access_funcs - access functions for buffers. 22 * @store_to: actually store stuff to the buffer 23 * @read: try to get a specified number of bytes (must exist) 24 * @data_available: indicates how much data is available for reading from 25 * the buffer. 26 * @request_update: if a parameter change has been marked, update underlying 27 * storage. 28 * @set_bytes_per_datum:set number of bytes per datum 29 * @set_length: set number of datums in buffer 30 * @enable: called if the buffer is attached to a device and the 31 * device starts sampling. Calls are balanced with 32 * @disable. 33 * @disable: called if the buffer is attached to a device and the 34 * device stops sampling. Calles are balanced with @enable. 35 * @release: called when the last reference to the buffer is dropped, 36 * should free all resources allocated by the buffer. 37 * @modes: Supported operating modes by this buffer type 38 * @flags: A bitmask combination of INDIO_BUFFER_FLAG_* 39 * 40 * The purpose of this structure is to make the buffer element 41 * modular as event for a given driver, different usecases may require 42 * different buffer designs (space efficiency vs speed for example). 43 * 44 * It is worth noting that a given buffer implementation may only support a 45 * small proportion of these functions. The core code 'should' cope fine with 46 * any of them not existing. 47 **/ 48 struct iio_buffer_access_funcs { 49 int (*store_to)(struct iio_buffer *buffer, const void *data); 50 int (*read)(struct iio_buffer *buffer, size_t n, char __user *buf); 51 size_t (*data_available)(struct iio_buffer *buffer); 52 53 int (*request_update)(struct iio_buffer *buffer); 54 55 int (*set_bytes_per_datum)(struct iio_buffer *buffer, size_t bpd); 56 int (*set_length)(struct iio_buffer *buffer, unsigned int length); 57 58 int (*enable)(struct iio_buffer *buffer, struct iio_dev *indio_dev); 59 int (*disable)(struct iio_buffer *buffer, struct iio_dev *indio_dev); 60 61 void (*release)(struct iio_buffer *buffer); 62 63 unsigned int modes; 64 unsigned int flags; 65 }; 66 67 /** 68 * struct iio_buffer - general buffer structure 69 * 70 * Note that the internals of this structure should only be of interest to 71 * those writing new buffer implementations. 72 */ 73 struct iio_buffer { 74 /** @length: Number of datums in buffer. */ 75 unsigned int length; 76 77 /** @flags: File ops flags including busy flag. */ 78 unsigned long flags; 79 80 /** @bytes_per_datum: Size of individual datum including timestamp. */ 81 size_t bytes_per_datum; 82 83 /** 84 * @access: Buffer access functions associated with the 85 * implementation. 86 */ 87 const struct iio_buffer_access_funcs *access; 88 89 /** @scan_mask: Bitmask used in masking scan mode elements. */ 90 long *scan_mask; 91 92 /** @demux_list: List of operations required to demux the scan. */ 93 struct list_head demux_list; 94 95 /** @pollq: Wait queue to allow for polling on the buffer. */ 96 wait_queue_head_t pollq; 97 98 /** @watermark: Number of datums to wait for poll/read. */ 99 unsigned int watermark; 100 101 /* private: */ 102 /* @scan_timestamp: Does the scan mode include a timestamp. */ 103 bool scan_timestamp; 104 105 /* @buffer_attr_list: List of buffer attributes. */ 106 struct list_head buffer_attr_list; 107 108 /* 109 * @buffer_group: Attributes of the new buffer group. 110 * Includes scan elements attributes. 111 */ 112 struct attribute_group buffer_group; 113 114 /* @attrs: Standard attributes of the buffer. */ 115 const struct attribute **attrs; 116 117 /* @demux_bounce: Buffer for doing gather from incoming scan. */ 118 void *demux_bounce; 119 120 /* @attached_entry: Entry in the devices list of buffers attached by the driver. */ 121 struct list_head attached_entry; 122 123 /* @buffer_list: Entry in the devices list of current buffers. */ 124 struct list_head buffer_list; 125 126 /* @ref: Reference count of the buffer. */ 127 struct kref ref; 128 }; 129 130 /** 131 * iio_update_buffers() - add or remove buffer from active list 132 * @indio_dev: device to add buffer to 133 * @insert_buffer: buffer to insert 134 * @remove_buffer: buffer_to_remove 135 * 136 * Note this will tear down the all buffering and build it up again 137 */ 138 int iio_update_buffers(struct iio_dev *indio_dev, 139 struct iio_buffer *insert_buffer, 140 struct iio_buffer *remove_buffer); 141 142 /** 143 * iio_buffer_init() - Initialize the buffer structure 144 * @buffer: buffer to be initialized 145 **/ 146 void iio_buffer_init(struct iio_buffer *buffer); 147 148 struct iio_buffer *iio_buffer_get(struct iio_buffer *buffer); 149 void iio_buffer_put(struct iio_buffer *buffer); 150 151 #else /* CONFIG_IIO_BUFFER */ 152 153 static inline void iio_buffer_get(struct iio_buffer *buffer) {} 154 static inline void iio_buffer_put(struct iio_buffer *buffer) {} 155 156 #endif /* CONFIG_IIO_BUFFER */ 157 #endif /* _IIO_BUFFER_GENERIC_IMPL_H_ */ 158