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