1 /* The industrial I/O core - generic buffer interfaces. 2 * 3 * Copyright (c) 2008 Jonathan Cameron 4 * 5 * This program is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 as published by 7 * the Free Software Foundation. 8 */ 9 10 #ifndef _IIO_BUFFER_GENERIC_H_ 11 #define _IIO_BUFFER_GENERIC_H_ 12 #include <linux/sysfs.h> 13 #include <linux/iio/iio.h> 14 #include <linux/kref.h> 15 16 #ifdef CONFIG_IIO_BUFFER 17 18 struct iio_buffer; 19 20 /** 21 * INDIO_BUFFER_FLAG_FIXED_WATERMARK - Watermark level of the buffer can not be 22 * configured. It has a fixed value which will be buffer specific. 23 */ 24 #define INDIO_BUFFER_FLAG_FIXED_WATERMARK BIT(0) 25 26 /** 27 * struct iio_buffer_access_funcs - access functions for buffers. 28 * @store_to: actually store stuff to the buffer 29 * @read_first_n: try to get a specified number of bytes (must exist) 30 * @data_available: indicates how much data is available for reading from 31 * the buffer. 32 * @request_update: if a parameter change has been marked, update underlying 33 * storage. 34 * @set_bytes_per_datum:set number of bytes per datum 35 * @set_length: set number of datums in buffer 36 * @enable: called if the buffer is attached to a device and the 37 * device starts sampling. Calls are balanced with 38 * @disable. 39 * @disable: called if the buffer is attached to a device and the 40 * device stops sampling. Calles are balanced with @enable. 41 * @release: called when the last reference to the buffer is dropped, 42 * should free all resources allocated by the buffer. 43 * @modes: Supported operating modes by this buffer type 44 * @flags: A bitmask combination of INDIO_BUFFER_FLAG_* 45 * 46 * The purpose of this structure is to make the buffer element 47 * modular as event for a given driver, different usecases may require 48 * different buffer designs (space efficiency vs speed for example). 49 * 50 * It is worth noting that a given buffer implementation may only support a 51 * small proportion of these functions. The core code 'should' cope fine with 52 * any of them not existing. 53 **/ 54 struct iio_buffer_access_funcs { 55 int (*store_to)(struct iio_buffer *buffer, const void *data); 56 int (*read_first_n)(struct iio_buffer *buffer, 57 size_t n, 58 char __user *buf); 59 size_t (*data_available)(struct iio_buffer *buffer); 60 61 int (*request_update)(struct iio_buffer *buffer); 62 63 int (*set_bytes_per_datum)(struct iio_buffer *buffer, size_t bpd); 64 int (*set_length)(struct iio_buffer *buffer, int length); 65 66 int (*enable)(struct iio_buffer *buffer, struct iio_dev *indio_dev); 67 int (*disable)(struct iio_buffer *buffer, struct iio_dev *indio_dev); 68 69 void (*release)(struct iio_buffer *buffer); 70 71 unsigned int modes; 72 unsigned int flags; 73 }; 74 75 /** 76 * struct iio_buffer - general buffer structure 77 * 78 * Note that the internals of this structure should only be of interest to 79 * those writing new buffer implementations. 80 */ 81 struct iio_buffer { 82 /** @length: Number of datums in buffer. */ 83 int length; 84 85 /** @bytes_per_datum: Size of individual datum including timestamp. */ 86 int bytes_per_datum; 87 88 /** 89 * @access: Buffer access functions associated with the 90 * implementation. 91 */ 92 const struct iio_buffer_access_funcs *access; 93 94 /** @scan_mask: Bitmask used in masking scan mode elements. */ 95 long *scan_mask; 96 97 /** @demux_list: List of operations required to demux the scan. */ 98 struct list_head demux_list; 99 100 /** @pollq: Wait queue to allow for polling on the buffer. */ 101 wait_queue_head_t pollq; 102 103 /** @watermark: Number of datums to wait for poll/read. */ 104 unsigned int watermark; 105 106 /* private: */ 107 /* 108 * @scan_el_attrs: Control of scan elements if that scan mode 109 * control method is used. 110 */ 111 struct attribute_group *scan_el_attrs; 112 113 /* @scan_timestamp: Does the scan mode include a timestamp. */ 114 bool scan_timestamp; 115 116 /* @scan_el_dev_attr_list: List of scan element related attributes. */ 117 struct list_head scan_el_dev_attr_list; 118 119 /* @buffer_group: Attributes of the buffer group. */ 120 struct attribute_group buffer_group; 121 122 /* 123 * @scan_el_group: Attribute group for those attributes not 124 * created from the iio_chan_info array. 125 */ 126 struct attribute_group scan_el_group; 127 128 /* @stufftoread: Flag to indicate new data. */ 129 bool stufftoread; 130 131 /* @attrs: Standard attributes of the buffer. */ 132 const struct attribute **attrs; 133 134 /* @demux_bounce: Buffer for doing gather from incoming scan. */ 135 void *demux_bounce; 136 137 /* @buffer_list: Entry in the devices list of current buffers. */ 138 struct list_head buffer_list; 139 140 /* @ref: Reference count of the buffer. */ 141 struct kref ref; 142 }; 143 144 /** 145 * iio_update_buffers() - add or remove buffer from active list 146 * @indio_dev: device to add buffer to 147 * @insert_buffer: buffer to insert 148 * @remove_buffer: buffer_to_remove 149 * 150 * Note this will tear down the all buffering and build it up again 151 */ 152 int iio_update_buffers(struct iio_dev *indio_dev, 153 struct iio_buffer *insert_buffer, 154 struct iio_buffer *remove_buffer); 155 156 /** 157 * iio_buffer_init() - Initialize the buffer structure 158 * @buffer: buffer to be initialized 159 **/ 160 void iio_buffer_init(struct iio_buffer *buffer); 161 162 int iio_scan_mask_query(struct iio_dev *indio_dev, 163 struct iio_buffer *buffer, int bit); 164 165 /** 166 * iio_push_to_buffers() - push to a registered buffer. 167 * @indio_dev: iio_dev structure for device. 168 * @data: Full scan. 169 */ 170 int iio_push_to_buffers(struct iio_dev *indio_dev, const void *data); 171 172 /* 173 * iio_push_to_buffers_with_timestamp() - push data and timestamp to buffers 174 * @indio_dev: iio_dev structure for device. 175 * @data: sample data 176 * @timestamp: timestamp for the sample data 177 * 178 * Pushes data to the IIO device's buffers. If timestamps are enabled for the 179 * device the function will store the supplied timestamp as the last element in 180 * the sample data buffer before pushing it to the device buffers. The sample 181 * data buffer needs to be large enough to hold the additional timestamp 182 * (usually the buffer should be indio->scan_bytes bytes large). 183 * 184 * Returns 0 on success, a negative error code otherwise. 185 */ 186 static inline int iio_push_to_buffers_with_timestamp(struct iio_dev *indio_dev, 187 void *data, int64_t timestamp) 188 { 189 if (indio_dev->scan_timestamp) { 190 size_t ts_offset = indio_dev->scan_bytes / sizeof(int64_t) - 1; 191 ((int64_t *)data)[ts_offset] = timestamp; 192 } 193 194 return iio_push_to_buffers(indio_dev, data); 195 } 196 197 bool iio_validate_scan_mask_onehot(struct iio_dev *indio_dev, 198 const unsigned long *mask); 199 200 struct iio_buffer *iio_buffer_get(struct iio_buffer *buffer); 201 void iio_buffer_put(struct iio_buffer *buffer); 202 203 /** 204 * iio_device_attach_buffer - Attach a buffer to a IIO device 205 * @indio_dev: The device the buffer should be attached to 206 * @buffer: The buffer to attach to the device 207 * 208 * This function attaches a buffer to a IIO device. The buffer stays attached to 209 * the device until the device is freed. The function should only be called at 210 * most once per device. 211 */ 212 static inline void iio_device_attach_buffer(struct iio_dev *indio_dev, 213 struct iio_buffer *buffer) 214 { 215 indio_dev->buffer = iio_buffer_get(buffer); 216 } 217 218 #else /* CONFIG_IIO_BUFFER */ 219 220 static inline void iio_buffer_get(struct iio_buffer *buffer) {} 221 static inline void iio_buffer_put(struct iio_buffer *buffer) {} 222 223 #endif /* CONFIG_IIO_BUFFER */ 224 225 #endif /* _IIO_BUFFER_GENERIC_H_ */ 226