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 * @length: [DEVICE] number of datums in buffer 78 * @bytes_per_datum: [DEVICE] size of individual datum including timestamp 79 * @scan_el_attrs: [DRIVER] control of scan elements if that scan mode 80 * control method is used 81 * @scan_mask: [INTERN] bitmask used in masking scan mode elements 82 * @scan_timestamp: [INTERN] does the scan mode include a timestamp 83 * @access: [DRIVER] buffer access functions associated with the 84 * implementation. 85 * @scan_el_dev_attr_list:[INTERN] list of scan element related attributes. 86 * @scan_el_group: [DRIVER] attribute group for those attributes not 87 * created from the iio_chan_info array. 88 * @pollq: [INTERN] wait queue to allow for polling on the buffer. 89 * @stufftoread: [INTERN] flag to indicate new data. 90 * @demux_list: [INTERN] list of operations required to demux the scan. 91 * @demux_bounce: [INTERN] buffer for doing gather from incoming scan. 92 * @buffer_list: [INTERN] entry in the devices list of current buffers. 93 * @ref: [INTERN] reference count of the buffer. 94 * @watermark: [INTERN] number of datums to wait for poll/read. 95 */ 96 struct iio_buffer { 97 int length; 98 int bytes_per_datum; 99 struct attribute_group *scan_el_attrs; 100 long *scan_mask; 101 bool scan_timestamp; 102 const struct iio_buffer_access_funcs *access; 103 struct list_head scan_el_dev_attr_list; 104 struct attribute_group buffer_group; 105 struct attribute_group scan_el_group; 106 wait_queue_head_t pollq; 107 bool stufftoread; 108 const struct attribute **attrs; 109 struct list_head demux_list; 110 void *demux_bounce; 111 struct list_head buffer_list; 112 struct kref ref; 113 unsigned int watermark; 114 }; 115 116 /** 117 * iio_update_buffers() - add or remove buffer from active list 118 * @indio_dev: device to add buffer to 119 * @insert_buffer: buffer to insert 120 * @remove_buffer: buffer_to_remove 121 * 122 * Note this will tear down the all buffering and build it up again 123 */ 124 int iio_update_buffers(struct iio_dev *indio_dev, 125 struct iio_buffer *insert_buffer, 126 struct iio_buffer *remove_buffer); 127 128 /** 129 * iio_buffer_init() - Initialize the buffer structure 130 * @buffer: buffer to be initialized 131 **/ 132 void iio_buffer_init(struct iio_buffer *buffer); 133 134 int iio_scan_mask_query(struct iio_dev *indio_dev, 135 struct iio_buffer *buffer, int bit); 136 137 /** 138 * iio_push_to_buffers() - push to a registered buffer. 139 * @indio_dev: iio_dev structure for device. 140 * @data: Full scan. 141 */ 142 int iio_push_to_buffers(struct iio_dev *indio_dev, const void *data); 143 144 /* 145 * iio_push_to_buffers_with_timestamp() - push data and timestamp to buffers 146 * @indio_dev: iio_dev structure for device. 147 * @data: sample data 148 * @timestamp: timestamp for the sample data 149 * 150 * Pushes data to the IIO device's buffers. If timestamps are enabled for the 151 * device the function will store the supplied timestamp as the last element in 152 * the sample data buffer before pushing it to the device buffers. The sample 153 * data buffer needs to be large enough to hold the additional timestamp 154 * (usually the buffer should be indio->scan_bytes bytes large). 155 * 156 * Returns 0 on success, a negative error code otherwise. 157 */ 158 static inline int iio_push_to_buffers_with_timestamp(struct iio_dev *indio_dev, 159 void *data, int64_t timestamp) 160 { 161 if (indio_dev->scan_timestamp) { 162 size_t ts_offset = indio_dev->scan_bytes / sizeof(int64_t) - 1; 163 ((int64_t *)data)[ts_offset] = timestamp; 164 } 165 166 return iio_push_to_buffers(indio_dev, data); 167 } 168 169 int iio_update_demux(struct iio_dev *indio_dev); 170 171 bool iio_validate_scan_mask_onehot(struct iio_dev *indio_dev, 172 const unsigned long *mask); 173 174 struct iio_buffer *iio_buffer_get(struct iio_buffer *buffer); 175 void iio_buffer_put(struct iio_buffer *buffer); 176 177 /** 178 * iio_device_attach_buffer - Attach a buffer to a IIO device 179 * @indio_dev: The device the buffer should be attached to 180 * @buffer: The buffer to attach to the device 181 * 182 * This function attaches a buffer to a IIO device. The buffer stays attached to 183 * the device until the device is freed. The function should only be called at 184 * most once per device. 185 */ 186 static inline void iio_device_attach_buffer(struct iio_dev *indio_dev, 187 struct iio_buffer *buffer) 188 { 189 indio_dev->buffer = iio_buffer_get(buffer); 190 } 191 192 #else /* CONFIG_IIO_BUFFER */ 193 194 static inline void iio_buffer_get(struct iio_buffer *buffer) {} 195 static inline void iio_buffer_put(struct iio_buffer *buffer) {} 196 197 #endif /* CONFIG_IIO_BUFFER */ 198 199 #endif /* _IIO_BUFFER_GENERIC_H_ */ 200