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1 | VME Device Driver API |
2 | ===================== | |
3 | ||
4 | Driver registration | |
5 | =================== | |
6 | ||
7 | As with other subsystems within the Linux kernel, VME device drivers register | |
8 | with the VME subsystem, typically called from the devices init routine. This is | |
9 | achieved via a call to the follwoing function: | |
10 | ||
11 | int vme_register_driver (struct vme_driver *driver); | |
12 | ||
13 | If driver registration is successful this function returns zero, if an error | |
14 | occurred a negative error code will be returned. | |
15 | ||
16 | A pointer to a structure of type 'vme_driver' must be provided to the | |
17 | registration function. The structure is as follows: | |
18 | ||
19 | struct vme_driver { | |
20 | struct list_head node; | |
21 | char *name; | |
22 | const struct vme_device_id *bind_table; | |
23 | int (*probe) (struct device *, int, int); | |
24 | int (*remove) (struct device *, int, int); | |
25 | void (*shutdown) (void); | |
26 | struct device_driver driver; | |
27 | }; | |
28 | ||
29 | At the minimum, the '.name', '.probe' and '.bind_table' elements of this | |
30 | structure should be correctly set. The '.name' element is a pointer to a string | |
31 | holding the device driver's name. The '.probe' element should contain a pointer | |
32 | to the probe routine. | |
33 | ||
34 | The arguments of the probe routine are as follows: | |
35 | ||
36 | probe(struct device *dev, int bus, int slot); | |
37 | ||
38 | The '.bind_table' is a pointer to an array of type 'vme_device_id': | |
39 | ||
40 | struct vme_device_id { | |
41 | int bus; | |
42 | int slot; | |
43 | }; | |
44 | ||
45 | Each structure in this array should provide a bus and slot number where the core | |
46 | should probe, using the driver's probe routine, for a device on the specified | |
47 | VME bus. | |
48 | ||
49 | The VME subsystem supports a single VME driver per 'slot'. There are considered | |
50 | to be 32 slots per bus, one for each slot-ID as defined in the ANSI/VITA 1-1994 | |
51 | specification and are analogious to the physical slots on the VME backplane. | |
52 | ||
53 | A function is also provided to unregister the driver from the VME core and is | |
54 | usually called from the device driver's exit routine: | |
55 | ||
56 | void vme_unregister_driver (struct vme_driver *driver); | |
57 | ||
58 | ||
59 | Resource management | |
60 | =================== | |
61 | ||
62 | Once a driver has registered with the VME core the provided probe routine will | |
63 | be called for each of the bus/slot combination that becomes valid as VME buses | |
64 | are themselves registered. The probe routine is passed a pointer to the devices | |
65 | device structure. This pointer should be saved, it will be required for | |
66 | requesting VME resources. | |
67 | ||
68 | The driver can request ownership of one or more master windows, slave windows | |
69 | and/or dma channels. Rather than allowing the device driver to request a | |
70 | specific window or DMA channel (which may be used by a different driver) this | |
71 | driver allows a resource to be assigned based on the required attributes of the | |
72 | driver in question: | |
73 | ||
74 | struct vme_resource * vme_master_request(struct device *dev, | |
75 | vme_address_t aspace, vme_cycle_t cycle, vme_width_t width); | |
76 | ||
77 | struct vme_resource * vme_slave_request(struct device *dev, | |
78 | vme_address_t aspace, vme_cycle_t cycle); | |
79 | ||
58e50798 | 80 | struct vme_resource *vme_dma_request(struct device *dev); |
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81 | |
82 | For slave windows these attributes are split into those of type 'vme_address_t' | |
83 | and 'vme_cycle_t'. Master windows add a further set of attributes 'vme_cycle_t'. | |
84 | These attributes are defined as bitmasks and as such any combination of the | |
85 | attributes can be requested for a single window, the core will assign a window | |
86 | that meets the requirements, returning a pointer of type vme_resource that | |
87 | should be used to identify the allocated resource when it is used. If an | |
88 | unallocated window fitting the requirements can not be found a NULL pointer will | |
89 | be returned. | |
90 | ||
91 | Functions are also provided to free window allocations once they are no longer | |
92 | required. These functions should be passed the pointer to the resource provided | |
93 | during resource allocation: | |
94 | ||
95 | void vme_master_free(struct vme_resource *res); | |
96 | ||
97 | void vme_slave_free(struct vme_resource *res); | |
98 | ||
99 | void vme_dma_free(struct vme_resource *res); | |
100 | ||
101 | ||
102 | Master windows | |
103 | ============== | |
104 | ||
105 | Master windows provide access from the local processor[s] out onto the VME bus. | |
106 | The number of windows available and the available access modes is dependant on | |
107 | the underlying chipset. A window must be configured before it can be used. | |
108 | ||
109 | ||
110 | Master window configuration | |
111 | --------------------------- | |
112 | ||
113 | Once a master window has been assigned the following functions can be used to | |
114 | configure it and retrieve the current settings: | |
115 | ||
116 | int vme_master_set (struct vme_resource *res, int enabled, | |
117 | unsigned long long base, unsigned long long size, | |
118 | vme_address_t aspace, vme_cycle_t cycle, vme_width_t width); | |
119 | ||
120 | int vme_master_get (struct vme_resource *res, int *enabled, | |
121 | unsigned long long *base, unsigned long long *size, | |
122 | vme_address_t *aspace, vme_cycle_t *cycle, vme_width_t *width); | |
123 | ||
124 | The address spaces, transfer widths and cycle types are the same as described | |
125 | under resource management, however some of the options are mutually exclusive. | |
126 | For example, only one address space may be specified. | |
127 | ||
128 | These functions return 0 on success or an error code should the call fail. | |
129 | ||
130 | ||
131 | Master window access | |
132 | -------------------- | |
133 | ||
134 | The following functions can be used to read from and write to configured master | |
135 | windows. These functions return the number of bytes copied: | |
136 | ||
137 | ssize_t vme_master_read(struct vme_resource *res, void *buf, | |
138 | size_t count, loff_t offset); | |
139 | ||
140 | ssize_t vme_master_write(struct vme_resource *res, void *buf, | |
141 | size_t count, loff_t offset); | |
142 | ||
143 | In addition to simple reads and writes, a function is provided to do a | |
144 | read-modify-write transaction. This function returns the original value of the | |
145 | VME bus location : | |
146 | ||
147 | unsigned int vme_master_rmw (struct vme_resource *res, | |
148 | unsigned int mask, unsigned int compare, unsigned int swap, | |
149 | loff_t offset); | |
150 | ||
151 | This functions by reading the offset, applying the mask. If the bits selected in | |
152 | the mask match with the values of the corresponding bits in the compare field, | |
153 | the value of swap is written the specified offset. | |
154 | ||
155 | ||
156 | Slave windows | |
157 | ============= | |
158 | ||
159 | Slave windows provide devices on the VME bus access into mapped portions of the | |
160 | local memory. The number of windows available and the access modes that can be | |
161 | used is dependant on the underlying chipset. A window must be configured before | |
162 | it can be used. | |
163 | ||
164 | ||
165 | Slave window configuration | |
166 | -------------------------- | |
167 | ||
168 | Once a slave window has been assigned the following functions can be used to | |
169 | configure it and retrieve the current settings: | |
170 | ||
171 | int vme_slave_set (struct vme_resource *res, int enabled, | |
172 | unsigned long long base, unsigned long long size, | |
173 | dma_addr_t mem, vme_address_t aspace, vme_cycle_t cycle); | |
174 | ||
175 | int vme_slave_get (struct vme_resource *res, int *enabled, | |
176 | unsigned long long *base, unsigned long long *size, | |
177 | dma_addr_t *mem, vme_address_t *aspace, vme_cycle_t *cycle); | |
178 | ||
179 | The address spaces, transfer widths and cycle types are the same as described | |
180 | under resource management, however some of the options are mutually exclusive. | |
181 | For example, only one address space may be specified. | |
182 | ||
183 | These functions return 0 on success or an error code should the call fail. | |
184 | ||
185 | ||
186 | Slave window buffer allocation | |
187 | ------------------------------ | |
188 | ||
189 | Functions are provided to allow the user to allocate and free a contiguous | |
190 | buffers which will be accessible by the VME bridge. These functions do not have | |
191 | to be used, other methods can be used to allocate a buffer, though care must be | |
192 | taken to ensure that they are contiguous and accessible by the VME bridge: | |
193 | ||
194 | void * vme_alloc_consistent(struct vme_resource *res, size_t size, | |
195 | dma_addr_t *mem); | |
196 | ||
197 | void vme_free_consistent(struct vme_resource *res, size_t size, | |
198 | void *virt, dma_addr_t mem); | |
199 | ||
200 | ||
201 | Slave window access | |
202 | ------------------- | |
203 | ||
204 | Slave windows map local memory onto the VME bus, the standard methods for | |
205 | accessing memory should be used. | |
206 | ||
207 | ||
208 | DMA channels | |
209 | ============ | |
210 | ||
211 | The VME DMA transfer provides the ability to run link-list DMA transfers. The | |
212 | API introduces the concept of DMA lists. Each DMA list is a link-list which can | |
213 | be passed to a DMA controller. Multiple lists can be created, extended, | |
214 | executed, reused and destroyed. | |
215 | ||
216 | ||
217 | List Management | |
218 | --------------- | |
219 | ||
220 | The following functions are provided to create and destroy DMA lists. Execution | |
221 | of a list will not automatically destroy the list, thus enabling a list to be | |
222 | reused for repetitive tasks: | |
223 | ||
224 | struct vme_dma_list *vme_new_dma_list(struct vme_resource *res); | |
225 | ||
226 | int vme_dma_list_free(struct vme_dma_list *list); | |
227 | ||
228 | ||
229 | List Population | |
230 | --------------- | |
231 | ||
232 | An item can be added to a list using the following function ( the source and | |
233 | destination attributes need to be created before calling this function, this is | |
234 | covered under "Transfer Attributes"): | |
235 | ||
236 | int vme_dma_list_add(struct vme_dma_list *list, | |
237 | struct vme_dma_attr *src, struct vme_dma_attr *dest, | |
238 | size_t count); | |
239 | ||
240 | ||
241 | Transfer Attributes | |
242 | ------------------- | |
243 | ||
244 | The attributes for the source and destination are handled separately from adding | |
245 | an item to a list. This is due to the diverse attributes required for each type | |
246 | of source and destination. There are functions to create attributes for PCI, VME | |
247 | and pattern sources and destinations (where appropriate): | |
248 | ||
249 | Pattern source: | |
250 | ||
251 | struct vme_dma_attr *vme_dma_pattern_attribute(u32 pattern, | |
252 | vme_pattern_t type); | |
253 | ||
254 | PCI source or destination: | |
255 | ||
256 | struct vme_dma_attr *vme_dma_pci_attribute(dma_addr_t mem); | |
257 | ||
258 | VME source or destination: | |
259 | ||
260 | struct vme_dma_attr *vme_dma_vme_attribute(unsigned long long base, | |
261 | vme_address_t aspace, vme_cycle_t cycle, vme_width_t width); | |
262 | ||
263 | The following function should be used to free an attribute: | |
264 | ||
265 | void vme_dma_free_attribute(struct vme_dma_attr *attr); | |
266 | ||
267 | ||
268 | List Execution | |
269 | -------------- | |
270 | ||
271 | The following function queues a list for execution. The function will return | |
272 | once the list has been executed: | |
273 | ||
274 | int vme_dma_list_exec(struct vme_dma_list *list); | |
275 | ||
276 | ||
277 | Interrupts | |
278 | ========== | |
279 | ||
280 | The VME API provides functions to attach and detach callbacks to specific VME | |
281 | level and status ID combinations and for the generation of VME interrupts with | |
282 | specific VME level and status IDs. | |
283 | ||
284 | ||
285 | Attaching Interrupt Handlers | |
286 | ---------------------------- | |
287 | ||
288 | The following functions can be used to attach and free a specific VME level and | |
289 | status ID combination. Any given combination can only be assigned a single | |
290 | callback function. A void pointer parameter is provided, the value of which is | |
291 | passed to the callback function, the use of this pointer is user undefined: | |
292 | ||
c813f592 | 293 | int vme_irq_request(struct device *dev, int level, int statid, |
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294 | void (*callback)(int, int, void *), void *priv); |
295 | ||
c813f592 | 296 | void vme_irq_free(struct device *dev, int level, int statid); |
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297 | |
298 | The callback parameters are as follows. Care must be taken in writing a callback | |
299 | function, callback functions run in interrupt context: | |
300 | ||
301 | void callback(int level, int statid, void *priv); | |
302 | ||
303 | ||
304 | Interrupt Generation | |
305 | -------------------- | |
306 | ||
307 | The following function can be used to generate a VME interrupt at a given VME | |
308 | level and VME status ID: | |
309 | ||
c813f592 | 310 | int vme_irq_generate(struct device *dev, int level, int statid); |
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311 | |
312 | ||
313 | Location monitors | |
314 | ================= | |
315 | ||
316 | The VME API provides the following functionality to configure the location | |
317 | monitor. | |
318 | ||
319 | ||
320 | Location Monitor Management | |
321 | --------------------------- | |
322 | ||
323 | The following functions are provided to request the use of a block of location | |
324 | monitors and to free them after they are no longer required: | |
325 | ||
326 | struct vme_resource * vme_lm_request(struct device *dev); | |
327 | ||
328 | void vme_lm_free(struct vme_resource * res); | |
329 | ||
330 | Each block may provide a number of location monitors, monitoring adjacent | |
331 | locations. The following function can be used to determine how many locations | |
332 | are provided: | |
333 | ||
334 | int vme_lm_count(struct vme_resource * res); | |
335 | ||
336 | ||
337 | Location Monitor Configuration | |
338 | ------------------------------ | |
339 | ||
340 | Once a bank of location monitors has been allocated, the following functions | |
341 | are provided to configure the location and mode of the location monitor: | |
342 | ||
343 | int vme_lm_set(struct vme_resource *res, unsigned long long base, | |
344 | vme_address_t aspace, vme_cycle_t cycle); | |
345 | ||
346 | int vme_lm_get(struct vme_resource *res, unsigned long long *base, | |
347 | vme_address_t *aspace, vme_cycle_t *cycle); | |
348 | ||
349 | ||
350 | Location Monitor Use | |
351 | -------------------- | |
352 | ||
353 | The following functions allow a callback to be attached and detached from each | |
354 | location monitor location. Each location monitor can monitor a number of | |
355 | adjacent locations: | |
356 | ||
357 | int vme_lm_attach(struct vme_resource *res, int num, | |
358 | void (*callback)(int)); | |
359 | ||
360 | int vme_lm_detach(struct vme_resource *res, int num); | |
361 | ||
362 | The callback function is declared as follows. | |
363 | ||
364 | void callback(int num); | |
365 | ||
366 | ||
367 | Slot Detection | |
368 | ============== | |
369 | ||
370 | This function returns the slot ID of the provided bridge. | |
371 | ||
372 | int vme_slot_get(struct device *dev); |