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_first_n: 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_first_n)(struct iio_buffer *buffer, 49 size_t n, 50 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 /** @bytes_per_datum: Size of individual datum including timestamp. */ 78 size_t bytes_per_datum; 79 80 /** 81 * @access: Buffer access functions associated with the 82 * implementation. 83 */ 84 const struct iio_buffer_access_funcs *access; 85 86 /** @scan_mask: Bitmask used in masking scan mode elements. */ 87 long *scan_mask; 88 89 /** @demux_list: List of operations required to demux the scan. */ 90 struct list_head demux_list; 91 92 /** @pollq: Wait queue to allow for polling on the buffer. */ 93 wait_queue_head_t pollq; 94 95 /** @watermark: Number of datums to wait for poll/read. */ 96 unsigned int watermark; 97 98 /* private: */ 99 /* 100 * @scan_el_attrs: Control of scan elements if that scan mode 101 * control method is used. 102 */ 103 struct attribute_group *scan_el_attrs; 104 105 /* @scan_timestamp: Does the scan mode include a timestamp. */ 106 bool scan_timestamp; 107 108 /* @scan_el_dev_attr_list: List of scan element related attributes. */ 109 struct list_head scan_el_dev_attr_list; 110 111 /* @buffer_group: Attributes of the buffer group. */ 112 struct attribute_group buffer_group; 113 114 /* 115 * @scan_el_group: Attribute group for those attributes not 116 * created from the iio_chan_info array. 117 */ 118 struct attribute_group scan_el_group; 119 120 /* @stufftoread: Flag to indicate new data. */ 121 bool stufftoread; 122 123 /* @attrs: Standard attributes of the buffer. */ 124 const struct attribute **attrs; 125 126 /* @demux_bounce: Buffer for doing gather from incoming scan. */ 127 void *demux_bounce; 128 129 /* @buffer_list: Entry in the devices list of current buffers. */ 130 struct list_head buffer_list; 131 132 /* @ref: Reference count of the buffer. */ 133 struct kref ref; 134 }; 135 136 /** 137 * iio_update_buffers() - add or remove buffer from active list 138 * @indio_dev: device to add buffer to 139 * @insert_buffer: buffer to insert 140 * @remove_buffer: buffer_to_remove 141 * 142 * Note this will tear down the all buffering and build it up again 143 */ 144 int iio_update_buffers(struct iio_dev *indio_dev, 145 struct iio_buffer *insert_buffer, 146 struct iio_buffer *remove_buffer); 147 148 /** 149 * iio_buffer_init() - Initialize the buffer structure 150 * @buffer: buffer to be initialized 151 **/ 152 void iio_buffer_init(struct iio_buffer *buffer); 153 154 struct iio_buffer *iio_buffer_get(struct iio_buffer *buffer); 155 void iio_buffer_put(struct iio_buffer *buffer); 156 157 #else /* CONFIG_IIO_BUFFER */ 158 159 static inline void iio_buffer_get(struct iio_buffer *buffer) {} 160 static inline void iio_buffer_put(struct iio_buffer *buffer) {} 161 162 #endif /* CONFIG_IIO_BUFFER */ 163 #endif /* _IIO_BUFFER_GENERIC_IMPL_H_ */ 164