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 * @release: called when the last reference to the buffer is dropped, 37 * should free all resources allocated by the buffer. 38 * @modes: Supported operating modes by this buffer type 39 * @flags: A bitmask combination of INDIO_BUFFER_FLAG_* 40 * 41 * The purpose of this structure is to make the buffer element 42 * modular as event for a given driver, different usecases may require 43 * different buffer designs (space efficiency vs speed for example). 44 * 45 * It is worth noting that a given buffer implementation may only support a 46 * small proportion of these functions. The core code 'should' cope fine with 47 * any of them not existing. 48 **/ 49 struct iio_buffer_access_funcs { 50 int (*store_to)(struct iio_buffer *buffer, const void *data); 51 int (*read_first_n)(struct iio_buffer *buffer, 52 size_t n, 53 char __user *buf); 54 size_t (*data_available)(struct iio_buffer *buffer); 55 56 int (*request_update)(struct iio_buffer *buffer); 57 58 int (*set_bytes_per_datum)(struct iio_buffer *buffer, size_t bpd); 59 int (*set_length)(struct iio_buffer *buffer, int length); 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 * @length: [DEVICE] number of datums in buffer 70 * @bytes_per_datum: [DEVICE] size of individual datum including timestamp 71 * @scan_el_attrs: [DRIVER] control of scan elements if that scan mode 72 * control method is used 73 * @scan_mask: [INTERN] bitmask used in masking scan mode elements 74 * @scan_timestamp: [INTERN] does the scan mode include a timestamp 75 * @access: [DRIVER] buffer access functions associated with the 76 * implementation. 77 * @scan_el_dev_attr_list:[INTERN] list of scan element related attributes. 78 * @scan_el_group: [DRIVER] attribute group for those attributes not 79 * created from the iio_chan_info array. 80 * @pollq: [INTERN] wait queue to allow for polling on the buffer. 81 * @stufftoread: [INTERN] flag to indicate new data. 82 * @demux_list: [INTERN] list of operations required to demux the scan. 83 * @demux_bounce: [INTERN] buffer for doing gather from incoming scan. 84 * @buffer_list: [INTERN] entry in the devices list of current buffers. 85 * @ref: [INTERN] reference count of the buffer. 86 * @watermark: [INTERN] number of datums to wait for poll/read. 87 */ 88 struct iio_buffer { 89 int length; 90 int bytes_per_datum; 91 struct attribute_group *scan_el_attrs; 92 long *scan_mask; 93 bool scan_timestamp; 94 const struct iio_buffer_access_funcs *access; 95 struct list_head scan_el_dev_attr_list; 96 struct attribute_group buffer_group; 97 struct attribute_group scan_el_group; 98 wait_queue_head_t pollq; 99 bool stufftoread; 100 const struct attribute **attrs; 101 struct list_head demux_list; 102 void *demux_bounce; 103 struct list_head buffer_list; 104 struct kref ref; 105 unsigned int watermark; 106 }; 107 108 /** 109 * iio_update_buffers() - add or remove buffer from active list 110 * @indio_dev: device to add buffer to 111 * @insert_buffer: buffer to insert 112 * @remove_buffer: buffer_to_remove 113 * 114 * Note this will tear down the all buffering and build it up again 115 */ 116 int iio_update_buffers(struct iio_dev *indio_dev, 117 struct iio_buffer *insert_buffer, 118 struct iio_buffer *remove_buffer); 119 120 /** 121 * iio_buffer_init() - Initialize the buffer structure 122 * @buffer: buffer to be initialized 123 **/ 124 void iio_buffer_init(struct iio_buffer *buffer); 125 126 int iio_scan_mask_query(struct iio_dev *indio_dev, 127 struct iio_buffer *buffer, int bit); 128 129 /** 130 * iio_push_to_buffers() - push to a registered buffer. 131 * @indio_dev: iio_dev structure for device. 132 * @data: Full scan. 133 */ 134 int iio_push_to_buffers(struct iio_dev *indio_dev, const void *data); 135 136 /* 137 * iio_push_to_buffers_with_timestamp() - push data and timestamp to buffers 138 * @indio_dev: iio_dev structure for device. 139 * @data: sample data 140 * @timestamp: timestamp for the sample data 141 * 142 * Pushes data to the IIO device's buffers. If timestamps are enabled for the 143 * device the function will store the supplied timestamp as the last element in 144 * the sample data buffer before pushing it to the device buffers. The sample 145 * data buffer needs to be large enough to hold the additional timestamp 146 * (usually the buffer should be indio->scan_bytes bytes large). 147 * 148 * Returns 0 on success, a negative error code otherwise. 149 */ 150 static inline int iio_push_to_buffers_with_timestamp(struct iio_dev *indio_dev, 151 void *data, int64_t timestamp) 152 { 153 if (indio_dev->scan_timestamp) { 154 size_t ts_offset = indio_dev->scan_bytes / sizeof(int64_t) - 1; 155 ((int64_t *)data)[ts_offset] = timestamp; 156 } 157 158 return iio_push_to_buffers(indio_dev, data); 159 } 160 161 int iio_update_demux(struct iio_dev *indio_dev); 162 163 bool iio_validate_scan_mask_onehot(struct iio_dev *indio_dev, 164 const unsigned long *mask); 165 166 struct iio_buffer *iio_buffer_get(struct iio_buffer *buffer); 167 void iio_buffer_put(struct iio_buffer *buffer); 168 169 /** 170 * iio_device_attach_buffer - Attach a buffer to a IIO device 171 * @indio_dev: The device the buffer should be attached to 172 * @buffer: The buffer to attach to the device 173 * 174 * This function attaches a buffer to a IIO device. The buffer stays attached to 175 * the device until the device is freed. The function should only be called at 176 * most once per device. 177 */ 178 static inline void iio_device_attach_buffer(struct iio_dev *indio_dev, 179 struct iio_buffer *buffer) 180 { 181 indio_dev->buffer = iio_buffer_get(buffer); 182 } 183 184 #else /* CONFIG_IIO_BUFFER */ 185 186 static inline void iio_buffer_get(struct iio_buffer *buffer) {} 187 static inline void iio_buffer_put(struct iio_buffer *buffer) {} 188 189 #endif /* CONFIG_IIO_BUFFER */ 190 191 #endif /* _IIO_BUFFER_GENERIC_H_ */ 192