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 * @get_bytes_per_datum:get current bytes per datum 29 * @set_bytes_per_datum:set number of bytes per datum 30 * @get_length: get number of datums in buffer 31 * @set_length: set number of datums in buffer 32 * @release: called when the last reference to the buffer is dropped, 33 * should free all resources allocated by the buffer. 34 * 35 * The purpose of this structure is to make the buffer element 36 * modular as event for a given driver, different usecases may require 37 * different buffer designs (space efficiency vs speed for example). 38 * 39 * It is worth noting that a given buffer implementation may only support a 40 * small proportion of these functions. The core code 'should' cope fine with 41 * any of them not existing. 42 **/ 43 struct iio_buffer_access_funcs { 44 int (*store_to)(struct iio_buffer *buffer, const void *data); 45 int (*read_first_n)(struct iio_buffer *buffer, 46 size_t n, 47 char __user *buf); 48 bool (*data_available)(struct iio_buffer *buffer); 49 50 int (*request_update)(struct iio_buffer *buffer); 51 52 int (*get_bytes_per_datum)(struct iio_buffer *buffer); 53 int (*set_bytes_per_datum)(struct iio_buffer *buffer, size_t bpd); 54 int (*get_length)(struct iio_buffer *buffer); 55 int (*set_length)(struct iio_buffer *buffer, int length); 56 57 void (*release)(struct iio_buffer *buffer); 58 }; 59 60 /** 61 * struct iio_buffer - general buffer structure 62 * @length: [DEVICE] number of datums in buffer 63 * @bytes_per_datum: [DEVICE] size of individual datum including timestamp 64 * @scan_el_attrs: [DRIVER] control of scan elements if that scan mode 65 * control method is used 66 * @scan_mask: [INTERN] bitmask used in masking scan mode elements 67 * @scan_timestamp: [INTERN] does the scan mode include a timestamp 68 * @access: [DRIVER] buffer access functions associated with the 69 * implementation. 70 * @scan_el_dev_attr_list:[INTERN] list of scan element related attributes. 71 * @scan_el_group: [DRIVER] attribute group for those attributes not 72 * created from the iio_chan_info array. 73 * @pollq: [INTERN] wait queue to allow for polling on the buffer. 74 * @stufftoread: [INTERN] flag to indicate new data. 75 * @demux_list: [INTERN] list of operations required to demux the scan. 76 * @demux_bounce: [INTERN] buffer for doing gather from incoming scan. 77 * @buffer_list: [INTERN] entry in the devices list of current buffers. 78 * @ref: [INTERN] reference count of the buffer. 79 */ 80 struct iio_buffer { 81 int length; 82 int bytes_per_datum; 83 struct attribute_group *scan_el_attrs; 84 long *scan_mask; 85 bool scan_timestamp; 86 const struct iio_buffer_access_funcs *access; 87 struct list_head scan_el_dev_attr_list; 88 struct attribute_group scan_el_group; 89 wait_queue_head_t pollq; 90 bool stufftoread; 91 const struct attribute_group *attrs; 92 struct list_head demux_list; 93 void *demux_bounce; 94 struct list_head buffer_list; 95 struct kref ref; 96 }; 97 98 /** 99 * iio_update_buffers() - add or remove buffer from active list 100 * @indio_dev: device to add buffer to 101 * @insert_buffer: buffer to insert 102 * @remove_buffer: buffer_to_remove 103 * 104 * Note this will tear down the all buffering and build it up again 105 */ 106 int iio_update_buffers(struct iio_dev *indio_dev, 107 struct iio_buffer *insert_buffer, 108 struct iio_buffer *remove_buffer); 109 110 /** 111 * iio_buffer_init() - Initialize the buffer structure 112 * @buffer: buffer to be initialized 113 **/ 114 void iio_buffer_init(struct iio_buffer *buffer); 115 116 int iio_scan_mask_query(struct iio_dev *indio_dev, 117 struct iio_buffer *buffer, int bit); 118 119 /** 120 * iio_scan_mask_set() - set particular bit in the scan mask 121 * @indio_dev IIO device structure 122 * @buffer: the buffer whose scan mask we are interested in 123 * @bit: the bit to be set. 124 **/ 125 int iio_scan_mask_set(struct iio_dev *indio_dev, 126 struct iio_buffer *buffer, int bit); 127 128 /** 129 * iio_push_to_buffers() - push to a registered buffer. 130 * @indio_dev: iio_dev structure for device. 131 * @data: Full scan. 132 */ 133 int iio_push_to_buffers(struct iio_dev *indio_dev, const void *data); 134 135 /* 136 * iio_push_to_buffers_with_timestamp() - push data and timestamp to buffers 137 * @indio_dev: iio_dev structure for device. 138 * @data: sample data 139 * @timestamp: timestamp for the sample data 140 * 141 * Pushes data to the IIO device's buffers. If timestamps are enabled for the 142 * device the function will store the supplied timestamp as the last element in 143 * the sample data buffer before pushing it to the device buffers. The sample 144 * data buffer needs to be large enough to hold the additional timestamp 145 * (usually the buffer should be indio->scan_bytes bytes large). 146 * 147 * Returns 0 on success, a negative error code otherwise. 148 */ 149 static inline int iio_push_to_buffers_with_timestamp(struct iio_dev *indio_dev, 150 void *data, int64_t timestamp) 151 { 152 if (indio_dev->scan_timestamp) { 153 size_t ts_offset = indio_dev->scan_bytes / sizeof(int64_t) - 1; 154 ((int64_t *)data)[ts_offset] = timestamp; 155 } 156 157 return iio_push_to_buffers(indio_dev, data); 158 } 159 160 int iio_update_demux(struct iio_dev *indio_dev); 161 162 /** 163 * iio_buffer_register() - register the buffer with IIO core 164 * @indio_dev: device with the buffer to be registered 165 * @channels: the channel descriptions used to construct buffer 166 * @num_channels: the number of channels 167 **/ 168 int iio_buffer_register(struct iio_dev *indio_dev, 169 const struct iio_chan_spec *channels, 170 int num_channels); 171 172 /** 173 * iio_buffer_unregister() - unregister the buffer from IIO core 174 * @indio_dev: the device with the buffer to be unregistered 175 **/ 176 void iio_buffer_unregister(struct iio_dev *indio_dev); 177 178 /** 179 * iio_buffer_read_length() - attr func to get number of datums in the buffer 180 **/ 181 ssize_t iio_buffer_read_length(struct device *dev, 182 struct device_attribute *attr, 183 char *buf); 184 /** 185 * iio_buffer_write_length() - attr func to set number of datums in the buffer 186 **/ 187 ssize_t iio_buffer_write_length(struct device *dev, 188 struct device_attribute *attr, 189 const char *buf, 190 size_t len); 191 /** 192 * iio_buffer_store_enable() - attr to turn the buffer on 193 **/ 194 ssize_t iio_buffer_store_enable(struct device *dev, 195 struct device_attribute *attr, 196 const char *buf, 197 size_t len); 198 /** 199 * iio_buffer_show_enable() - attr to see if the buffer is on 200 **/ 201 ssize_t iio_buffer_show_enable(struct device *dev, 202 struct device_attribute *attr, 203 char *buf); 204 #define IIO_BUFFER_LENGTH_ATTR DEVICE_ATTR(length, S_IRUGO | S_IWUSR, \ 205 iio_buffer_read_length, \ 206 iio_buffer_write_length) 207 208 #define IIO_BUFFER_ENABLE_ATTR DEVICE_ATTR(enable, S_IRUGO | S_IWUSR, \ 209 iio_buffer_show_enable, \ 210 iio_buffer_store_enable) 211 212 bool iio_validate_scan_mask_onehot(struct iio_dev *indio_dev, 213 const unsigned long *mask); 214 215 struct iio_buffer *iio_buffer_get(struct iio_buffer *buffer); 216 void iio_buffer_put(struct iio_buffer *buffer); 217 218 /** 219 * iio_device_attach_buffer - Attach a buffer to a IIO device 220 * @indio_dev: The device the buffer should be attached to 221 * @buffer: The buffer to attach to the device 222 * 223 * This function attaches a buffer to a IIO device. The buffer stays attached to 224 * the device until the device is freed. The function should only be called at 225 * most once per device. 226 */ 227 static inline void iio_device_attach_buffer(struct iio_dev *indio_dev, 228 struct iio_buffer *buffer) 229 { 230 indio_dev->buffer = iio_buffer_get(buffer); 231 } 232 233 #else /* CONFIG_IIO_BUFFER */ 234 235 static inline int iio_buffer_register(struct iio_dev *indio_dev, 236 const struct iio_chan_spec *channels, 237 int num_channels) 238 { 239 return 0; 240 } 241 242 static inline void iio_buffer_unregister(struct iio_dev *indio_dev) 243 {} 244 245 static inline void iio_buffer_get(struct iio_buffer *buffer) {} 246 static inline void iio_buffer_put(struct iio_buffer *buffer) {} 247 248 #endif /* CONFIG_IIO_BUFFER */ 249 250 #endif /* _IIO_BUFFER_GENERIC_H_ */ 251