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 struct iio_dev; 10 struct iio_buffer; 11 12 /** 13 * INDIO_BUFFER_FLAG_FIXED_WATERMARK - Watermark level of the buffer can not be 14 * configured. It has a fixed value which will be buffer specific. 15 */ 16 #define INDIO_BUFFER_FLAG_FIXED_WATERMARK BIT(0) 17 18 /** 19 * struct iio_buffer_access_funcs - access functions for buffers. 20 * @store_to: actually store stuff to the buffer 21 * @read: try to get a specified number of bytes (must exist) 22 * @data_available: indicates how much data is available for reading from 23 * the buffer. 24 * @request_update: if a parameter change has been marked, update underlying 25 * storage. 26 * @set_bytes_per_datum:set number of bytes per datum 27 * @set_length: set number of datums in buffer 28 * @enable: called if the buffer is attached to a device and the 29 * device starts sampling. Calls are balanced with 30 * @disable. 31 * @disable: called if the buffer is attached to a device and the 32 * device stops sampling. Calles are balanced with @enable. 33 * @release: called when the last reference to the buffer is dropped, 34 * should free all resources allocated by the buffer. 35 * @modes: Supported operating modes by this buffer type 36 * @flags: A bitmask combination of INDIO_BUFFER_FLAG_* 37 * 38 * The purpose of this structure is to make the buffer element 39 * modular as event for a given driver, different usecases may require 40 * different buffer designs (space efficiency vs speed for example). 41 * 42 * It is worth noting that a given buffer implementation may only support a 43 * small proportion of these functions. The core code 'should' cope fine with 44 * any of them not existing. 45 **/ 46 struct iio_buffer_access_funcs { 47 int (*store_to)(struct iio_buffer *buffer, const void *data); 48 int (*read)(struct iio_buffer *buffer, size_t n, char __user *buf); 49 size_t (*data_available)(struct iio_buffer *buffer); 50 51 int (*request_update)(struct iio_buffer *buffer); 52 53 int (*set_bytes_per_datum)(struct iio_buffer *buffer, size_t bpd); 54 int (*set_length)(struct iio_buffer *buffer, unsigned int length); 55 56 int (*enable)(struct iio_buffer *buffer, struct iio_dev *indio_dev); 57 int (*disable)(struct iio_buffer *buffer, struct iio_dev *indio_dev); 58 59 void (*release)(struct iio_buffer *buffer); 60 61 unsigned int modes; 62 unsigned int flags; 63 }; 64 65 /** 66 * struct iio_buffer - general buffer structure 67 * 68 * Note that the internals of this structure should only be of interest to 69 * those writing new buffer implementations. 70 */ 71 struct iio_buffer { 72 /** @length: Number of datums in buffer. */ 73 unsigned int length; 74 75 /** @bytes_per_datum: Size of individual datum including timestamp. */ 76 size_t bytes_per_datum; 77 78 /** 79 * @access: Buffer access functions associated with the 80 * implementation. 81 */ 82 const struct iio_buffer_access_funcs *access; 83 84 /** @scan_mask: Bitmask used in masking scan mode elements. */ 85 long *scan_mask; 86 87 /** @demux_list: List of operations required to demux the scan. */ 88 struct list_head demux_list; 89 90 /** @pollq: Wait queue to allow for polling on the buffer. */ 91 wait_queue_head_t pollq; 92 93 /** @watermark: Number of datums to wait for poll/read. */ 94 unsigned int watermark; 95 96 /* private: */ 97 /* 98 * @scan_el_attrs: Control of scan elements if that scan mode 99 * control method is used. 100 */ 101 struct attribute_group *scan_el_attrs; 102 103 /* @scan_timestamp: Does the scan mode include a timestamp. */ 104 bool scan_timestamp; 105 106 /* @scan_el_dev_attr_list: List of scan element related attributes. */ 107 struct list_head scan_el_dev_attr_list; 108 109 /* @buffer_group: Attributes of the buffer group. */ 110 struct attribute_group buffer_group; 111 112 /* 113 * @scan_el_group: Attribute group for those attributes not 114 * created from the iio_chan_info array. 115 */ 116 struct attribute_group scan_el_group; 117 118 /* @stufftoread: Flag to indicate new data. */ 119 bool stufftoread; 120 121 /* @attrs: Standard attributes of the buffer. */ 122 const struct attribute **attrs; 123 124 /* @demux_bounce: Buffer for doing gather from incoming scan. */ 125 void *demux_bounce; 126 127 /* @buffer_list: Entry in the devices list of current buffers. */ 128 struct list_head buffer_list; 129 130 /* @ref: Reference count of the buffer. */ 131 struct kref ref; 132 }; 133 134 /** 135 * iio_update_buffers() - add or remove buffer from active list 136 * @indio_dev: device to add buffer to 137 * @insert_buffer: buffer to insert 138 * @remove_buffer: buffer_to_remove 139 * 140 * Note this will tear down the all buffering and build it up again 141 */ 142 int iio_update_buffers(struct iio_dev *indio_dev, 143 struct iio_buffer *insert_buffer, 144 struct iio_buffer *remove_buffer); 145 146 /** 147 * iio_buffer_init() - Initialize the buffer structure 148 * @buffer: buffer to be initialized 149 **/ 150 void iio_buffer_init(struct iio_buffer *buffer); 151 152 struct iio_buffer *iio_buffer_get(struct iio_buffer *buffer); 153 void iio_buffer_put(struct iio_buffer *buffer); 154 155 #else /* CONFIG_IIO_BUFFER */ 156 157 static inline void iio_buffer_get(struct iio_buffer *buffer) {} 158 static inline void iio_buffer_put(struct iio_buffer *buffer) {} 159 160 #endif /* CONFIG_IIO_BUFFER */ 161 #endif /* _IIO_BUFFER_GENERIC_IMPL_H_ */ 162