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 scan_el_group; 87 wait_queue_head_t pollq; 88 bool stufftoread; 89 const struct attribute_group *attrs; 90 struct list_head demux_list; 91 void *demux_bounce; 92 struct list_head buffer_list; 93 struct kref ref; 94 }; 95 96 /** 97 * iio_update_buffers() - add or remove buffer from active list 98 * @indio_dev: device to add buffer to 99 * @insert_buffer: buffer to insert 100 * @remove_buffer: buffer_to_remove 101 * 102 * Note this will tear down the all buffering and build it up again 103 */ 104 int iio_update_buffers(struct iio_dev *indio_dev, 105 struct iio_buffer *insert_buffer, 106 struct iio_buffer *remove_buffer); 107 108 /** 109 * iio_buffer_init() - Initialize the buffer structure 110 * @buffer: buffer to be initialized 111 **/ 112 void iio_buffer_init(struct iio_buffer *buffer); 113 114 int iio_scan_mask_query(struct iio_dev *indio_dev, 115 struct iio_buffer *buffer, int bit); 116 117 /** 118 * iio_push_to_buffers() - push to a registered buffer. 119 * @indio_dev: iio_dev structure for device. 120 * @data: Full scan. 121 */ 122 int iio_push_to_buffers(struct iio_dev *indio_dev, const void *data); 123 124 /* 125 * iio_push_to_buffers_with_timestamp() - push data and timestamp to buffers 126 * @indio_dev: iio_dev structure for device. 127 * @data: sample data 128 * @timestamp: timestamp for the sample data 129 * 130 * Pushes data to the IIO device's buffers. If timestamps are enabled for the 131 * device the function will store the supplied timestamp as the last element in 132 * the sample data buffer before pushing it to the device buffers. The sample 133 * data buffer needs to be large enough to hold the additional timestamp 134 * (usually the buffer should be indio->scan_bytes bytes large). 135 * 136 * Returns 0 on success, a negative error code otherwise. 137 */ 138 static inline int iio_push_to_buffers_with_timestamp(struct iio_dev *indio_dev, 139 void *data, int64_t timestamp) 140 { 141 if (indio_dev->scan_timestamp) { 142 size_t ts_offset = indio_dev->scan_bytes / sizeof(int64_t) - 1; 143 ((int64_t *)data)[ts_offset] = timestamp; 144 } 145 146 return iio_push_to_buffers(indio_dev, data); 147 } 148 149 int iio_update_demux(struct iio_dev *indio_dev); 150 151 /** 152 * iio_buffer_read_length() - attr func to get number of datums in the buffer 153 **/ 154 ssize_t iio_buffer_read_length(struct device *dev, 155 struct device_attribute *attr, 156 char *buf); 157 /** 158 * iio_buffer_write_length() - attr func to set number of datums in the buffer 159 **/ 160 ssize_t iio_buffer_write_length(struct device *dev, 161 struct device_attribute *attr, 162 const char *buf, 163 size_t len); 164 /** 165 * iio_buffer_store_enable() - attr to turn the buffer on 166 **/ 167 ssize_t iio_buffer_store_enable(struct device *dev, 168 struct device_attribute *attr, 169 const char *buf, 170 size_t len); 171 /** 172 * iio_buffer_show_enable() - attr to see if the buffer is on 173 **/ 174 ssize_t iio_buffer_show_enable(struct device *dev, 175 struct device_attribute *attr, 176 char *buf); 177 #define IIO_BUFFER_LENGTH_ATTR DEVICE_ATTR(length, S_IRUGO | S_IWUSR, \ 178 iio_buffer_read_length, \ 179 iio_buffer_write_length) 180 181 #define IIO_BUFFER_ENABLE_ATTR DEVICE_ATTR(enable, S_IRUGO | S_IWUSR, \ 182 iio_buffer_show_enable, \ 183 iio_buffer_store_enable) 184 185 bool iio_validate_scan_mask_onehot(struct iio_dev *indio_dev, 186 const unsigned long *mask); 187 188 struct iio_buffer *iio_buffer_get(struct iio_buffer *buffer); 189 void iio_buffer_put(struct iio_buffer *buffer); 190 191 /** 192 * iio_device_attach_buffer - Attach a buffer to a IIO device 193 * @indio_dev: The device the buffer should be attached to 194 * @buffer: The buffer to attach to the device 195 * 196 * This function attaches a buffer to a IIO device. The buffer stays attached to 197 * the device until the device is freed. The function should only be called at 198 * most once per device. 199 */ 200 static inline void iio_device_attach_buffer(struct iio_dev *indio_dev, 201 struct iio_buffer *buffer) 202 { 203 indio_dev->buffer = iio_buffer_get(buffer); 204 } 205 206 #else /* CONFIG_IIO_BUFFER */ 207 208 static inline void iio_buffer_get(struct iio_buffer *buffer) {} 209 static inline void iio_buffer_put(struct iio_buffer *buffer) {} 210 211 #endif /* CONFIG_IIO_BUFFER */ 212 213 #endif /* _IIO_BUFFER_GENERIC_H_ */ 214