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bf39f9a5 MW |
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 | |
25985edc | 9 | achieved via a call to the following function: |
bf39f9a5 | 10 | |
76deefa3 | 11 | int vme_register_driver (struct vme_driver *driver, unsigned int ndevs); |
bf39f9a5 MW |
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 | |
76deefa3 MW |
17 | registration function. Along with ndevs, which is the number of devices your |
18 | driver is able to support. The structure is as follows: | |
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19 | |
20 | struct vme_driver { | |
21 | struct list_head node; | |
5d6abf37 MV |
22 | const char *name; |
23 | int (*match)(struct vme_dev *); | |
24 | int (*probe)(struct vme_dev *); | |
25 | int (*remove)(struct vme_dev *); | |
26 | void (*shutdown)(void); | |
27 | struct device_driver driver; | |
28 | struct list_head devices; | |
29 | unsigned int ndev; | |
bf39f9a5 MW |
30 | }; |
31 | ||
5d6abf37 MV |
32 | At the minimum, the '.name', '.match' and '.probe' elements of this structure |
33 | should be correctly set. The '.name' element is a pointer to a string holding | |
34 | the device driver's name. | |
bf39f9a5 | 35 | |
76deefa3 MW |
36 | The '.match' function allows control over which VME devices should be registered |
37 | with the driver. The match function should return 1 if a device should be | |
5d6abf37 MV |
38 | probed and 0 otherwise. This example match function (from vme_user.c) limits |
39 | the number of devices probed to one: | |
bf39f9a5 | 40 | |
5d6abf37 MV |
41 | #define USER_BUS_MAX 1 |
42 | ... | |
43 | static int vme_user_match(struct vme_dev *vdev) | |
44 | { | |
45 | if (vdev->id.num >= USER_BUS_MAX) | |
46 | return 0; | |
47 | return 1; | |
48 | } | |
8f966dc4 | 49 | |
5d6abf37 MV |
50 | The '.probe' element should contain a pointer to the probe routine. The |
51 | probe routine is passed a 'struct vme_dev' pointer as an argument. The | |
52 | 'struct vme_dev' structure looks like the following: | |
8f966dc4 MV |
53 | |
54 | struct vme_dev { | |
a916a391 | 55 | int num; |
8f966dc4 MV |
56 | struct vme_bridge *bridge; |
57 | struct device dev; | |
a916a391 MV |
58 | struct list_head drv_list; |
59 | struct list_head bridge_list; | |
8f966dc4 MV |
60 | }; |
61 | ||
a916a391 MV |
62 | Here, the 'num' field refers to the sequential device ID for this specific |
63 | driver. The bridge number (or bus number) can be accessed using | |
64 | dev->bridge->num. | |
bf39f9a5 MW |
65 | |
66 | A function is also provided to unregister the driver from the VME core and is | |
67 | usually called from the device driver's exit routine: | |
68 | ||
69 | void vme_unregister_driver (struct vme_driver *driver); | |
70 | ||
71 | ||
72 | Resource management | |
73 | =================== | |
74 | ||
a916a391 MV |
75 | Once a driver has registered with the VME core the provided match routine will |
76 | be called the number of times specified during the registration. If a match | |
77 | succeeds, a non-zero value should be returned. A zero return value indicates | |
78 | failure. For all successful matches, the probe routine of the corresponding | |
79 | driver is called. The probe routine is passed a pointer to the devices | |
bf39f9a5 MW |
80 | device structure. This pointer should be saved, it will be required for |
81 | requesting VME resources. | |
82 | ||
83 | The driver can request ownership of one or more master windows, slave windows | |
84 | and/or dma channels. Rather than allowing the device driver to request a | |
85 | specific window or DMA channel (which may be used by a different driver) this | |
86 | driver allows a resource to be assigned based on the required attributes of the | |
87 | driver in question: | |
88 | ||
8f966dc4 | 89 | struct vme_resource * vme_master_request(struct vme_dev *dev, |
6af04b06 MW |
90 | u32 aspace, u32 cycle, u32 width); |
91 | ||
92 | struct vme_resource * vme_slave_request(struct vme_dev *dev, u32 aspace, | |
93 | u32 cycle); | |
94 | ||
95 | struct vme_resource *vme_dma_request(struct vme_dev *dev, u32 route); | |
96 | ||
97 | For slave windows these attributes are split into the VME address spaces that | |
98 | need to be accessed in 'aspace' and VME bus cycle types required in 'cycle'. | |
99 | Master windows add a further set of attributes in 'width' specifying the | |
100 | required data transfer widths. These attributes are defined as bitmasks and as | |
101 | such any combination of the attributes can be requested for a single window, | |
102 | the core will assign a window that meets the requirements, returning a pointer | |
103 | of type vme_resource that should be used to identify the allocated resource | |
104 | when it is used. For DMA controllers, the request function requires the | |
105 | potential direction of any transfers to be provided in the route attributes. | |
106 | This is typically VME-to-MEM and/or MEM-to-VME, though some hardware can | |
107 | support VME-to-VME and MEM-to-MEM transfers as well as test pattern generation. | |
108 | If an unallocated window fitting the requirements can not be found a NULL | |
109 | pointer will be returned. | |
bf39f9a5 MW |
110 | |
111 | Functions are also provided to free window allocations once they are no longer | |
112 | required. These functions should be passed the pointer to the resource provided | |
113 | during resource allocation: | |
114 | ||
115 | void vme_master_free(struct vme_resource *res); | |
116 | ||
117 | void vme_slave_free(struct vme_resource *res); | |
118 | ||
119 | void vme_dma_free(struct vme_resource *res); | |
120 | ||
121 | ||
122 | Master windows | |
123 | ============== | |
124 | ||
125 | Master windows provide access from the local processor[s] out onto the VME bus. | |
25985edc | 126 | The number of windows available and the available access modes is dependent on |
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127 | the underlying chipset. A window must be configured before it can be used. |
128 | ||
129 | ||
130 | Master window configuration | |
131 | --------------------------- | |
132 | ||
133 | Once a master window has been assigned the following functions can be used to | |
134 | configure it and retrieve the current settings: | |
135 | ||
136 | int vme_master_set (struct vme_resource *res, int enabled, | |
6af04b06 MW |
137 | unsigned long long base, unsigned long long size, u32 aspace, |
138 | u32 cycle, u32 width); | |
bf39f9a5 MW |
139 | |
140 | int vme_master_get (struct vme_resource *res, int *enabled, | |
6af04b06 MW |
141 | unsigned long long *base, unsigned long long *size, u32 *aspace, |
142 | u32 *cycle, u32 *width); | |
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143 | |
144 | The address spaces, transfer widths and cycle types are the same as described | |
145 | under resource management, however some of the options are mutually exclusive. | |
146 | For example, only one address space may be specified. | |
147 | ||
148 | These functions return 0 on success or an error code should the call fail. | |
149 | ||
150 | ||
151 | Master window access | |
152 | -------------------- | |
153 | ||
154 | The following functions can be used to read from and write to configured master | |
155 | windows. These functions return the number of bytes copied: | |
156 | ||
157 | ssize_t vme_master_read(struct vme_resource *res, void *buf, | |
158 | size_t count, loff_t offset); | |
159 | ||
160 | ssize_t vme_master_write(struct vme_resource *res, void *buf, | |
161 | size_t count, loff_t offset); | |
162 | ||
163 | In addition to simple reads and writes, a function is provided to do a | |
164 | read-modify-write transaction. This function returns the original value of the | |
165 | VME bus location : | |
166 | ||
167 | unsigned int vme_master_rmw (struct vme_resource *res, | |
168 | unsigned int mask, unsigned int compare, unsigned int swap, | |
169 | loff_t offset); | |
170 | ||
171 | This functions by reading the offset, applying the mask. If the bits selected in | |
172 | the mask match with the values of the corresponding bits in the compare field, | |
173 | the value of swap is written the specified offset. | |
174 | ||
c5ab1f7f DK |
175 | Parts of a VME window can be mapped into user space memory using the following |
176 | function: | |
177 | ||
178 | int vme_master_mmap(struct vme_resource *resource, | |
179 | struct vm_area_struct *vma) | |
180 | ||
bf39f9a5 MW |
181 | |
182 | Slave windows | |
183 | ============= | |
184 | ||
185 | Slave windows provide devices on the VME bus access into mapped portions of the | |
186 | local memory. The number of windows available and the access modes that can be | |
25985edc | 187 | used is dependent on the underlying chipset. A window must be configured before |
bf39f9a5 MW |
188 | it can be used. |
189 | ||
190 | ||
191 | Slave window configuration | |
192 | -------------------------- | |
193 | ||
194 | Once a slave window has been assigned the following functions can be used to | |
195 | configure it and retrieve the current settings: | |
196 | ||
197 | int vme_slave_set (struct vme_resource *res, int enabled, | |
198 | unsigned long long base, unsigned long long size, | |
6af04b06 | 199 | dma_addr_t mem, u32 aspace, u32 cycle); |
bf39f9a5 MW |
200 | |
201 | int vme_slave_get (struct vme_resource *res, int *enabled, | |
202 | unsigned long long *base, unsigned long long *size, | |
6af04b06 | 203 | dma_addr_t *mem, u32 *aspace, u32 *cycle); |
bf39f9a5 MW |
204 | |
205 | The address spaces, transfer widths and cycle types are the same as described | |
206 | under resource management, however some of the options are mutually exclusive. | |
207 | For example, only one address space may be specified. | |
208 | ||
209 | These functions return 0 on success or an error code should the call fail. | |
210 | ||
211 | ||
212 | Slave window buffer allocation | |
213 | ------------------------------ | |
214 | ||
215 | Functions are provided to allow the user to allocate and free a contiguous | |
216 | buffers which will be accessible by the VME bridge. These functions do not have | |
217 | to be used, other methods can be used to allocate a buffer, though care must be | |
218 | taken to ensure that they are contiguous and accessible by the VME bridge: | |
219 | ||
220 | void * vme_alloc_consistent(struct vme_resource *res, size_t size, | |
221 | dma_addr_t *mem); | |
222 | ||
223 | void vme_free_consistent(struct vme_resource *res, size_t size, | |
224 | void *virt, dma_addr_t mem); | |
225 | ||
226 | ||
227 | Slave window access | |
228 | ------------------- | |
229 | ||
230 | Slave windows map local memory onto the VME bus, the standard methods for | |
231 | accessing memory should be used. | |
232 | ||
233 | ||
234 | DMA channels | |
235 | ============ | |
236 | ||
237 | The VME DMA transfer provides the ability to run link-list DMA transfers. The | |
238 | API introduces the concept of DMA lists. Each DMA list is a link-list which can | |
239 | be passed to a DMA controller. Multiple lists can be created, extended, | |
240 | executed, reused and destroyed. | |
241 | ||
242 | ||
243 | List Management | |
244 | --------------- | |
245 | ||
246 | The following functions are provided to create and destroy DMA lists. Execution | |
247 | of a list will not automatically destroy the list, thus enabling a list to be | |
248 | reused for repetitive tasks: | |
249 | ||
250 | struct vme_dma_list *vme_new_dma_list(struct vme_resource *res); | |
251 | ||
252 | int vme_dma_list_free(struct vme_dma_list *list); | |
253 | ||
254 | ||
255 | List Population | |
256 | --------------- | |
257 | ||
258 | An item can be added to a list using the following function ( the source and | |
259 | destination attributes need to be created before calling this function, this is | |
260 | covered under "Transfer Attributes"): | |
261 | ||
262 | int vme_dma_list_add(struct vme_dma_list *list, | |
263 | struct vme_dma_attr *src, struct vme_dma_attr *dest, | |
264 | size_t count); | |
265 | ||
4f723df4 MW |
266 | NOTE: The detailed attributes of the transfers source and destination |
267 | are not checked until an entry is added to a DMA list, the request | |
268 | for a DMA channel purely checks the directions in which the | |
269 | controller is expected to transfer data. As a result it is | |
270 | possible for this call to return an error, for example if the | |
271 | source or destination is in an unsupported VME address space. | |
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272 | |
273 | Transfer Attributes | |
274 | ------------------- | |
275 | ||
276 | The attributes for the source and destination are handled separately from adding | |
277 | an item to a list. This is due to the diverse attributes required for each type | |
278 | of source and destination. There are functions to create attributes for PCI, VME | |
279 | and pattern sources and destinations (where appropriate): | |
280 | ||
281 | Pattern source: | |
282 | ||
6af04b06 | 283 | struct vme_dma_attr *vme_dma_pattern_attribute(u32 pattern, u32 type); |
bf39f9a5 MW |
284 | |
285 | PCI source or destination: | |
286 | ||
287 | struct vme_dma_attr *vme_dma_pci_attribute(dma_addr_t mem); | |
288 | ||
289 | VME source or destination: | |
290 | ||
291 | struct vme_dma_attr *vme_dma_vme_attribute(unsigned long long base, | |
6af04b06 | 292 | u32 aspace, u32 cycle, u32 width); |
bf39f9a5 MW |
293 | |
294 | The following function should be used to free an attribute: | |
295 | ||
296 | void vme_dma_free_attribute(struct vme_dma_attr *attr); | |
297 | ||
298 | ||
299 | List Execution | |
300 | -------------- | |
301 | ||
302 | The following function queues a list for execution. The function will return | |
303 | once the list has been executed: | |
304 | ||
305 | int vme_dma_list_exec(struct vme_dma_list *list); | |
306 | ||
307 | ||
308 | Interrupts | |
309 | ========== | |
310 | ||
311 | The VME API provides functions to attach and detach callbacks to specific VME | |
312 | level and status ID combinations and for the generation of VME interrupts with | |
313 | specific VME level and status IDs. | |
314 | ||
315 | ||
316 | Attaching Interrupt Handlers | |
317 | ---------------------------- | |
318 | ||
319 | The following functions can be used to attach and free a specific VME level and | |
320 | status ID combination. Any given combination can only be assigned a single | |
321 | callback function. A void pointer parameter is provided, the value of which is | |
322 | passed to the callback function, the use of this pointer is user undefined: | |
323 | ||
8f966dc4 | 324 | int vme_irq_request(struct vme_dev *dev, int level, int statid, |
bf39f9a5 MW |
325 | void (*callback)(int, int, void *), void *priv); |
326 | ||
8f966dc4 | 327 | void vme_irq_free(struct vme_dev *dev, int level, int statid); |
bf39f9a5 MW |
328 | |
329 | The callback parameters are as follows. Care must be taken in writing a callback | |
330 | function, callback functions run in interrupt context: | |
331 | ||
332 | void callback(int level, int statid, void *priv); | |
333 | ||
334 | ||
335 | Interrupt Generation | |
336 | -------------------- | |
337 | ||
338 | The following function can be used to generate a VME interrupt at a given VME | |
339 | level and VME status ID: | |
340 | ||
8f966dc4 | 341 | int vme_irq_generate(struct vme_dev *dev, int level, int statid); |
bf39f9a5 MW |
342 | |
343 | ||
344 | Location monitors | |
345 | ================= | |
346 | ||
347 | The VME API provides the following functionality to configure the location | |
348 | monitor. | |
349 | ||
350 | ||
351 | Location Monitor Management | |
352 | --------------------------- | |
353 | ||
354 | The following functions are provided to request the use of a block of location | |
355 | monitors and to free them after they are no longer required: | |
356 | ||
8f966dc4 | 357 | struct vme_resource * vme_lm_request(struct vme_dev *dev); |
bf39f9a5 MW |
358 | |
359 | void vme_lm_free(struct vme_resource * res); | |
360 | ||
361 | Each block may provide a number of location monitors, monitoring adjacent | |
362 | locations. The following function can be used to determine how many locations | |
363 | are provided: | |
364 | ||
365 | int vme_lm_count(struct vme_resource * res); | |
366 | ||
367 | ||
368 | Location Monitor Configuration | |
369 | ------------------------------ | |
370 | ||
371 | Once a bank of location monitors has been allocated, the following functions | |
372 | are provided to configure the location and mode of the location monitor: | |
373 | ||
374 | int vme_lm_set(struct vme_resource *res, unsigned long long base, | |
6af04b06 | 375 | u32 aspace, u32 cycle); |
bf39f9a5 MW |
376 | |
377 | int vme_lm_get(struct vme_resource *res, unsigned long long *base, | |
6af04b06 | 378 | u32 *aspace, u32 *cycle); |
bf39f9a5 MW |
379 | |
380 | ||
381 | Location Monitor Use | |
382 | -------------------- | |
383 | ||
384 | The following functions allow a callback to be attached and detached from each | |
385 | location monitor location. Each location monitor can monitor a number of | |
386 | adjacent locations: | |
387 | ||
388 | int vme_lm_attach(struct vme_resource *res, int num, | |
fa54b326 | 389 | void (*callback)(void *)); |
bf39f9a5 MW |
390 | |
391 | int vme_lm_detach(struct vme_resource *res, int num); | |
392 | ||
393 | The callback function is declared as follows. | |
394 | ||
fa54b326 | 395 | void callback(void *data); |
bf39f9a5 MW |
396 | |
397 | ||
398 | Slot Detection | |
399 | ============== | |
400 | ||
401 | This function returns the slot ID of the provided bridge. | |
402 | ||
d7729f0f | 403 | int vme_slot_num(struct vme_dev *dev); |
978f47d6 MW |
404 | |
405 | ||
406 | Bus Detection | |
407 | ============= | |
408 | ||
409 | This function returns the bus ID of the provided bridge. | |
410 | ||
411 | int vme_bus_num(struct vme_dev *dev); | |
412 | ||
413 |