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 * @request_update: if a parameter change has been marked, update underlying 25 * storage. 26 * @get_bytes_per_datum:get current bytes per datum 27 * @set_bytes_per_datum:set number of bytes per datum 28 * @get_length: get number of datums in buffer 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 47 int (*request_update)(struct iio_buffer *buffer); 48 49 int (*get_bytes_per_datum)(struct iio_buffer *buffer); 50 int (*set_bytes_per_datum)(struct iio_buffer *buffer, size_t bpd); 51 int (*get_length)(struct iio_buffer *buffer); 52 int (*set_length)(struct iio_buffer *buffer, int length); 53 54 void (*release)(struct iio_buffer *buffer); 55 }; 56 57 /** 58 * struct iio_buffer - general buffer structure 59 * @length: [DEVICE] number of datums in buffer 60 * @bytes_per_datum: [DEVICE] size of individual datum including timestamp 61 * @scan_el_attrs: [DRIVER] control of scan elements if that scan mode 62 * control method is used 63 * @scan_mask: [INTERN] bitmask used in masking scan mode elements 64 * @scan_timestamp: [INTERN] does the scan mode include a timestamp 65 * @access: [DRIVER] buffer access functions associated with the 66 * implementation. 67 * @scan_el_dev_attr_list:[INTERN] list of scan element related attributes. 68 * @scan_el_group: [DRIVER] attribute group for those attributes not 69 * created from the iio_chan_info array. 70 * @pollq: [INTERN] wait queue to allow for polling on the buffer. 71 * @stufftoread: [INTERN] flag to indicate new data. 72 * @demux_list: [INTERN] list of operations required to demux the scan. 73 * @demux_bounce: [INTERN] buffer for doing gather from incoming scan. 74 * @buffer_list: [INTERN] entry in the devices list of current buffers. 75 * @ref: [INTERN] reference count of the buffer. 76 */ 77 struct iio_buffer { 78 int length; 79 int bytes_per_datum; 80 struct attribute_group *scan_el_attrs; 81 long *scan_mask; 82 bool scan_timestamp; 83 const struct iio_buffer_access_funcs *access; 84 struct list_head scan_el_dev_attr_list; 85 struct attribute_group scan_el_group; 86 wait_queue_head_t pollq; 87 bool stufftoread; 88 const struct attribute_group *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_scan_mask_set() - set particular bit in the scan mask 118 * @indio_dev IIO device structure 119 * @buffer: the buffer whose scan mask we are interested in 120 * @bit: the bit to be set. 121 **/ 122 int iio_scan_mask_set(struct iio_dev *indio_dev, 123 struct iio_buffer *buffer, int bit); 124 125 /** 126 * iio_push_to_buffers() - push to a registered buffer. 127 * @indio_dev: iio_dev structure for device. 128 * @data: Full scan. 129 */ 130 int iio_push_to_buffers(struct iio_dev *indio_dev, const void *data); 131 132 /* 133 * iio_push_to_buffers_with_timestamp() - push data and timestamp to buffers 134 * @indio_dev: iio_dev structure for device. 135 * @data: sample data 136 * @timestamp: timestamp for the sample data 137 * 138 * Pushes data to the IIO device's buffers. If timestamps are enabled for the 139 * device the function will store the supplied timestamp as the last element in 140 * the sample data buffer before pushing it to the device buffers. The sample 141 * data buffer needs to be large enough to hold the additional timestamp 142 * (usually the buffer should be indio->scan_bytes bytes large). 143 * 144 * Returns 0 on success, a negative error code otherwise. 145 */ 146 static inline int iio_push_to_buffers_with_timestamp(struct iio_dev *indio_dev, 147 void *data, int64_t timestamp) 148 { 149 if (indio_dev->scan_timestamp) { 150 size_t ts_offset = indio_dev->scan_bytes / sizeof(int64_t) - 1; 151 ((int64_t *)data)[ts_offset] = timestamp; 152 } 153 154 return iio_push_to_buffers(indio_dev, data); 155 } 156 157 int iio_update_demux(struct iio_dev *indio_dev); 158 159 /** 160 * iio_buffer_register() - register the buffer with IIO core 161 * @indio_dev: device with the buffer to be registered 162 * @channels: the channel descriptions used to construct buffer 163 * @num_channels: the number of channels 164 **/ 165 int iio_buffer_register(struct iio_dev *indio_dev, 166 const struct iio_chan_spec *channels, 167 int num_channels); 168 169 /** 170 * iio_buffer_unregister() - unregister the buffer from IIO core 171 * @indio_dev: the device with the buffer to be unregistered 172 **/ 173 void iio_buffer_unregister(struct iio_dev *indio_dev); 174 175 /** 176 * iio_buffer_read_length() - attr func to get number of datums in the buffer 177 **/ 178 ssize_t iio_buffer_read_length(struct device *dev, 179 struct device_attribute *attr, 180 char *buf); 181 /** 182 * iio_buffer_write_length() - attr func to set number of datums in the buffer 183 **/ 184 ssize_t iio_buffer_write_length(struct device *dev, 185 struct device_attribute *attr, 186 const char *buf, 187 size_t len); 188 /** 189 * iio_buffer_store_enable() - attr to turn the buffer on 190 **/ 191 ssize_t iio_buffer_store_enable(struct device *dev, 192 struct device_attribute *attr, 193 const char *buf, 194 size_t len); 195 /** 196 * iio_buffer_show_enable() - attr to see if the buffer is on 197 **/ 198 ssize_t iio_buffer_show_enable(struct device *dev, 199 struct device_attribute *attr, 200 char *buf); 201 #define IIO_BUFFER_LENGTH_ATTR DEVICE_ATTR(length, S_IRUGO | S_IWUSR, \ 202 iio_buffer_read_length, \ 203 iio_buffer_write_length) 204 205 #define IIO_BUFFER_ENABLE_ATTR DEVICE_ATTR(enable, S_IRUGO | S_IWUSR, \ 206 iio_buffer_show_enable, \ 207 iio_buffer_store_enable) 208 209 bool iio_validate_scan_mask_onehot(struct iio_dev *indio_dev, 210 const unsigned long *mask); 211 212 struct iio_buffer *iio_buffer_get(struct iio_buffer *buffer); 213 void iio_buffer_put(struct iio_buffer *buffer); 214 215 /** 216 * iio_device_attach_buffer - Attach a buffer to a IIO device 217 * @indio_dev: The device the buffer should be attached to 218 * @buffer: The buffer to attach to the device 219 * 220 * This function attaches a buffer to a IIO device. The buffer stays attached to 221 * the device until the device is freed. The function should only be called at 222 * most once per device. 223 */ 224 static inline void iio_device_attach_buffer(struct iio_dev *indio_dev, 225 struct iio_buffer *buffer) 226 { 227 indio_dev->buffer = iio_buffer_get(buffer); 228 } 229 230 #else /* CONFIG_IIO_BUFFER */ 231 232 static inline int iio_buffer_register(struct iio_dev *indio_dev, 233 const struct iio_chan_spec *channels, 234 int num_channels) 235 { 236 return 0; 237 } 238 239 static inline void iio_buffer_unregister(struct iio_dev *indio_dev) 240 {} 241 242 static inline void iio_buffer_get(struct iio_buffer *buffer) {} 243 static inline void iio_buffer_put(struct iio_buffer *buffer) {} 244 245 #endif /* CONFIG_IIO_BUFFER */ 246 247 #endif /* _IIO_BUFFER_GENERIC_H_ */ 248