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