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 * struct iio_buffer_access_funcs - access functions for buffers. 22 * @store_to: actually store stuff to the buffer 23 * @read_first_n: try to get a specified number of bytes (must exist) 24 * @data_available: indicates whether data for reading from the buffer is 25 * available. 26 * @request_update: if a parameter change has been marked, update underlying 27 * storage. 28 * @set_bytes_per_datum:set number of bytes per datum 29 * @get_length: get number of datums in buffer 30 * @set_length: set number of datums in buffer 31 * @release: called when the last reference to the buffer is dropped, 32 * should free all resources allocated by the buffer. 33 * 34 * The purpose of this structure is to make the buffer element 35 * modular as event for a given driver, different usecases may require 36 * different buffer designs (space efficiency vs speed for example). 37 * 38 * It is worth noting that a given buffer implementation may only support a 39 * small proportion of these functions. The core code 'should' cope fine with 40 * any of them not existing. 41 **/ 42 struct iio_buffer_access_funcs { 43 int (*store_to)(struct iio_buffer *buffer, const void *data); 44 int (*read_first_n)(struct iio_buffer *buffer, 45 size_t n, 46 char __user *buf); 47 bool (*data_available)(struct iio_buffer *buffer); 48 49 int (*request_update)(struct iio_buffer *buffer); 50 51 int (*set_bytes_per_datum)(struct iio_buffer *buffer, size_t bpd); 52 int (*get_length)(struct iio_buffer *buffer); 53 int (*set_length)(struct iio_buffer *buffer, int length); 54 55 void (*release)(struct iio_buffer *buffer); 56 }; 57 58 /** 59 * struct iio_buffer - general buffer structure 60 * @length: [DEVICE] number of datums in buffer 61 * @bytes_per_datum: [DEVICE] size of individual datum including timestamp 62 * @scan_el_attrs: [DRIVER] control of scan elements if that scan mode 63 * control method is used 64 * @scan_mask: [INTERN] bitmask used in masking scan mode elements 65 * @scan_timestamp: [INTERN] does the scan mode include a timestamp 66 * @access: [DRIVER] buffer access functions associated with the 67 * implementation. 68 * @scan_el_dev_attr_list:[INTERN] list of scan element related attributes. 69 * @scan_el_group: [DRIVER] attribute group for those attributes not 70 * created from the iio_chan_info array. 71 * @pollq: [INTERN] wait queue to allow for polling on the buffer. 72 * @stufftoread: [INTERN] flag to indicate new data. 73 * @demux_list: [INTERN] list of operations required to demux the scan. 74 * @demux_bounce: [INTERN] buffer for doing gather from incoming scan. 75 * @buffer_list: [INTERN] entry in the devices list of current buffers. 76 * @ref: [INTERN] reference count of the buffer. 77 */ 78 struct iio_buffer { 79 int length; 80 int bytes_per_datum; 81 struct attribute_group *scan_el_attrs; 82 long *scan_mask; 83 bool scan_timestamp; 84 const struct iio_buffer_access_funcs *access; 85 struct list_head scan_el_dev_attr_list; 86 struct attribute_group buffer_group; 87 struct attribute_group scan_el_group; 88 wait_queue_head_t pollq; 89 bool stufftoread; 90 const struct attribute **attrs; 91 struct list_head demux_list; 92 void *demux_bounce; 93 struct list_head buffer_list; 94 struct kref ref; 95 }; 96 97 /** 98 * iio_update_buffers() - add or remove buffer from active list 99 * @indio_dev: device to add buffer to 100 * @insert_buffer: buffer to insert 101 * @remove_buffer: buffer_to_remove 102 * 103 * Note this will tear down the all buffering and build it up again 104 */ 105 int iio_update_buffers(struct iio_dev *indio_dev, 106 struct iio_buffer *insert_buffer, 107 struct iio_buffer *remove_buffer); 108 109 /** 110 * iio_buffer_init() - Initialize the buffer structure 111 * @buffer: buffer to be initialized 112 **/ 113 void iio_buffer_init(struct iio_buffer *buffer); 114 115 int iio_scan_mask_query(struct iio_dev *indio_dev, 116 struct iio_buffer *buffer, int bit); 117 118 /** 119 * iio_push_to_buffers() - push to a registered buffer. 120 * @indio_dev: iio_dev structure for device. 121 * @data: Full scan. 122 */ 123 int iio_push_to_buffers(struct iio_dev *indio_dev, const void *data); 124 125 /* 126 * iio_push_to_buffers_with_timestamp() - push data and timestamp to buffers 127 * @indio_dev: iio_dev structure for device. 128 * @data: sample data 129 * @timestamp: timestamp for the sample data 130 * 131 * Pushes data to the IIO device's buffers. If timestamps are enabled for the 132 * device the function will store the supplied timestamp as the last element in 133 * the sample data buffer before pushing it to the device buffers. The sample 134 * data buffer needs to be large enough to hold the additional timestamp 135 * (usually the buffer should be indio->scan_bytes bytes large). 136 * 137 * Returns 0 on success, a negative error code otherwise. 138 */ 139 static inline int iio_push_to_buffers_with_timestamp(struct iio_dev *indio_dev, 140 void *data, int64_t timestamp) 141 { 142 if (indio_dev->scan_timestamp) { 143 size_t ts_offset = indio_dev->scan_bytes / sizeof(int64_t) - 1; 144 ((int64_t *)data)[ts_offset] = timestamp; 145 } 146 147 return iio_push_to_buffers(indio_dev, data); 148 } 149 150 int iio_update_demux(struct iio_dev *indio_dev); 151 152 bool iio_validate_scan_mask_onehot(struct iio_dev *indio_dev, 153 const unsigned long *mask); 154 155 struct iio_buffer *iio_buffer_get(struct iio_buffer *buffer); 156 void iio_buffer_put(struct iio_buffer *buffer); 157 158 /** 159 * iio_device_attach_buffer - Attach a buffer to a IIO device 160 * @indio_dev: The device the buffer should be attached to 161 * @buffer: The buffer to attach to the device 162 * 163 * This function attaches a buffer to a IIO device. The buffer stays attached to 164 * the device until the device is freed. The function should only be called at 165 * most once per device. 166 */ 167 static inline void iio_device_attach_buffer(struct iio_dev *indio_dev, 168 struct iio_buffer *buffer) 169 { 170 indio_dev->buffer = iio_buffer_get(buffer); 171 } 172 173 #else /* CONFIG_IIO_BUFFER */ 174 175 static inline void iio_buffer_get(struct iio_buffer *buffer) {} 176 static inline void iio_buffer_put(struct iio_buffer *buffer) {} 177 178 #endif /* CONFIG_IIO_BUFFER */ 179 180 #endif /* _IIO_BUFFER_GENERIC_H_ */ 181