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[linux-2.6-block.git] / Documentation / vme_api.txt
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1 VME Device Driver API
2 =====================
3
4Driver registration
5===================
6
7As with other subsystems within the Linux kernel, VME device drivers register
8with the VME subsystem, typically called from the devices init routine. This is
25985edc 9achieved via a call to the following function:
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10
11 int vme_register_driver (struct vme_driver *driver);
12
13If driver registration is successful this function returns zero, if an error
14occurred a negative error code will be returned.
15
16A pointer to a structure of type 'vme_driver' must be provided to the
17registration function. The structure is as follows:
18
19 struct vme_driver {
20 struct list_head node;
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21 const char *name;
22 int (*match)(struct vme_dev *);
23 int (*probe)(struct vme_dev *);
24 int (*remove)(struct vme_dev *);
25 void (*shutdown)(void);
26 struct device_driver driver;
27 struct list_head devices;
28 unsigned int ndev;
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29 };
30
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31At the minimum, the '.name', '.match' and '.probe' elements of this structure
32should be correctly set. The '.name' element is a pointer to a string holding
33the device driver's name.
bf39f9a5 34
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35The '.match' function allows controlling the number of devices that need to
36be registered. The match function should return 1 if a device should be
37probed and 0 otherwise. This example match function (from vme_user.c) limits
38the number of devices probed to one:
bf39f9a5 39
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40 #define USER_BUS_MAX 1
41 ...
42 static int vme_user_match(struct vme_dev *vdev)
43 {
44 if (vdev->id.num >= USER_BUS_MAX)
45 return 0;
46 return 1;
47 }
8f966dc4 48
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49The '.probe' element should contain a pointer to the probe routine. The
50probe routine is passed a 'struct vme_dev' pointer as an argument. The
51'struct vme_dev' structure looks like the following:
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52
53 struct vme_dev {
a916a391 54 int num;
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55 struct vme_bridge *bridge;
56 struct device dev;
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57 struct list_head drv_list;
58 struct list_head bridge_list;
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59 };
60
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61Here, the 'num' field refers to the sequential device ID for this specific
62driver. The bridge number (or bus number) can be accessed using
63dev->bridge->num.
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64
65A function is also provided to unregister the driver from the VME core and is
66usually called from the device driver's exit routine:
67
68 void vme_unregister_driver (struct vme_driver *driver);
69
70
71Resource management
72===================
73
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74Once a driver has registered with the VME core the provided match routine will
75be called the number of times specified during the registration. If a match
76succeeds, a non-zero value should be returned. A zero return value indicates
77failure. For all successful matches, the probe routine of the corresponding
78driver is called. The probe routine is passed a pointer to the devices
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79device structure. This pointer should be saved, it will be required for
80requesting VME resources.
81
82The driver can request ownership of one or more master windows, slave windows
83and/or dma channels. Rather than allowing the device driver to request a
84specific window or DMA channel (which may be used by a different driver) this
85driver allows a resource to be assigned based on the required attributes of the
86driver in question:
87
8f966dc4 88 struct vme_resource * vme_master_request(struct vme_dev *dev,
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89 u32 aspace, u32 cycle, u32 width);
90
91 struct vme_resource * vme_slave_request(struct vme_dev *dev, u32 aspace,
92 u32 cycle);
93
94 struct vme_resource *vme_dma_request(struct vme_dev *dev, u32 route);
95
96For slave windows these attributes are split into the VME address spaces that
97need to be accessed in 'aspace' and VME bus cycle types required in 'cycle'.
98Master windows add a further set of attributes in 'width' specifying the
99required data transfer widths. These attributes are defined as bitmasks and as
100such any combination of the attributes can be requested for a single window,
101the core will assign a window that meets the requirements, returning a pointer
102of type vme_resource that should be used to identify the allocated resource
103when it is used. For DMA controllers, the request function requires the
104potential direction of any transfers to be provided in the route attributes.
105This is typically VME-to-MEM and/or MEM-to-VME, though some hardware can
106support VME-to-VME and MEM-to-MEM transfers as well as test pattern generation.
107If an unallocated window fitting the requirements can not be found a NULL
108pointer will be returned.
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109
110Functions are also provided to free window allocations once they are no longer
111required. These functions should be passed the pointer to the resource provided
112during resource allocation:
113
114 void vme_master_free(struct vme_resource *res);
115
116 void vme_slave_free(struct vme_resource *res);
117
118 void vme_dma_free(struct vme_resource *res);
119
120
121Master windows
122==============
123
124Master windows provide access from the local processor[s] out onto the VME bus.
25985edc 125The number of windows available and the available access modes is dependent on
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126the underlying chipset. A window must be configured before it can be used.
127
128
129Master window configuration
130---------------------------
131
132Once a master window has been assigned the following functions can be used to
133configure it and retrieve the current settings:
134
135 int vme_master_set (struct vme_resource *res, int enabled,
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136 unsigned long long base, unsigned long long size, u32 aspace,
137 u32 cycle, u32 width);
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138
139 int vme_master_get (struct vme_resource *res, int *enabled,
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140 unsigned long long *base, unsigned long long *size, u32 *aspace,
141 u32 *cycle, u32 *width);
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142
143The address spaces, transfer widths and cycle types are the same as described
144under resource management, however some of the options are mutually exclusive.
145For example, only one address space may be specified.
146
147These functions return 0 on success or an error code should the call fail.
148
149
150Master window access
151--------------------
152
153The following functions can be used to read from and write to configured master
154windows. These functions return the number of bytes copied:
155
156 ssize_t vme_master_read(struct vme_resource *res, void *buf,
157 size_t count, loff_t offset);
158
159 ssize_t vme_master_write(struct vme_resource *res, void *buf,
160 size_t count, loff_t offset);
161
162In addition to simple reads and writes, a function is provided to do a
163read-modify-write transaction. This function returns the original value of the
164VME bus location :
165
166 unsigned int vme_master_rmw (struct vme_resource *res,
167 unsigned int mask, unsigned int compare, unsigned int swap,
168 loff_t offset);
169
170This functions by reading the offset, applying the mask. If the bits selected in
171the mask match with the values of the corresponding bits in the compare field,
172the value of swap is written the specified offset.
173
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174Parts of a VME window can be mapped into user space memory using the following
175function:
176
177 int vme_master_mmap(struct vme_resource *resource,
178 struct vm_area_struct *vma)
179
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180
181Slave windows
182=============
183
184Slave windows provide devices on the VME bus access into mapped portions of the
185local memory. The number of windows available and the access modes that can be
25985edc 186used is dependent on the underlying chipset. A window must be configured before
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187it can be used.
188
189
190Slave window configuration
191--------------------------
192
193Once a slave window has been assigned the following functions can be used to
194configure it and retrieve the current settings:
195
196 int vme_slave_set (struct vme_resource *res, int enabled,
197 unsigned long long base, unsigned long long size,
6af04b06 198 dma_addr_t mem, u32 aspace, u32 cycle);
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199
200 int vme_slave_get (struct vme_resource *res, int *enabled,
201 unsigned long long *base, unsigned long long *size,
6af04b06 202 dma_addr_t *mem, u32 *aspace, u32 *cycle);
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203
204The address spaces, transfer widths and cycle types are the same as described
205under resource management, however some of the options are mutually exclusive.
206For example, only one address space may be specified.
207
208These functions return 0 on success or an error code should the call fail.
209
210
211Slave window buffer allocation
212------------------------------
213
214Functions are provided to allow the user to allocate and free a contiguous
215buffers which will be accessible by the VME bridge. These functions do not have
216to be used, other methods can be used to allocate a buffer, though care must be
217taken to ensure that they are contiguous and accessible by the VME bridge:
218
219 void * vme_alloc_consistent(struct vme_resource *res, size_t size,
220 dma_addr_t *mem);
221
222 void vme_free_consistent(struct vme_resource *res, size_t size,
223 void *virt, dma_addr_t mem);
224
225
226Slave window access
227-------------------
228
229Slave windows map local memory onto the VME bus, the standard methods for
230accessing memory should be used.
231
232
233DMA channels
234============
235
236The VME DMA transfer provides the ability to run link-list DMA transfers. The
237API introduces the concept of DMA lists. Each DMA list is a link-list which can
238be passed to a DMA controller. Multiple lists can be created, extended,
239executed, reused and destroyed.
240
241
242List Management
243---------------
244
245The following functions are provided to create and destroy DMA lists. Execution
246of a list will not automatically destroy the list, thus enabling a list to be
247reused for repetitive tasks:
248
249 struct vme_dma_list *vme_new_dma_list(struct vme_resource *res);
250
251 int vme_dma_list_free(struct vme_dma_list *list);
252
253
254List Population
255---------------
256
257An item can be added to a list using the following function ( the source and
258destination attributes need to be created before calling this function, this is
259covered under "Transfer Attributes"):
260
261 int vme_dma_list_add(struct vme_dma_list *list,
262 struct vme_dma_attr *src, struct vme_dma_attr *dest,
263 size_t count);
264
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265NOTE: The detailed attributes of the transfers source and destination
266 are not checked until an entry is added to a DMA list, the request
267 for a DMA channel purely checks the directions in which the
268 controller is expected to transfer data. As a result it is
269 possible for this call to return an error, for example if the
270 source or destination is in an unsupported VME address space.
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271
272Transfer Attributes
273-------------------
274
275The attributes for the source and destination are handled separately from adding
276an item to a list. This is due to the diverse attributes required for each type
277of source and destination. There are functions to create attributes for PCI, VME
278and pattern sources and destinations (where appropriate):
279
280Pattern source:
281
6af04b06 282 struct vme_dma_attr *vme_dma_pattern_attribute(u32 pattern, u32 type);
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283
284PCI source or destination:
285
286 struct vme_dma_attr *vme_dma_pci_attribute(dma_addr_t mem);
287
288VME source or destination:
289
290 struct vme_dma_attr *vme_dma_vme_attribute(unsigned long long base,
6af04b06 291 u32 aspace, u32 cycle, u32 width);
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292
293The following function should be used to free an attribute:
294
295 void vme_dma_free_attribute(struct vme_dma_attr *attr);
296
297
298List Execution
299--------------
300
301The following function queues a list for execution. The function will return
302once the list has been executed:
303
304 int vme_dma_list_exec(struct vme_dma_list *list);
305
306
307Interrupts
308==========
309
310The VME API provides functions to attach and detach callbacks to specific VME
311level and status ID combinations and for the generation of VME interrupts with
312specific VME level and status IDs.
313
314
315Attaching Interrupt Handlers
316----------------------------
317
318The following functions can be used to attach and free a specific VME level and
319status ID combination. Any given combination can only be assigned a single
320callback function. A void pointer parameter is provided, the value of which is
321passed to the callback function, the use of this pointer is user undefined:
322
8f966dc4 323 int vme_irq_request(struct vme_dev *dev, int level, int statid,
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324 void (*callback)(int, int, void *), void *priv);
325
8f966dc4 326 void vme_irq_free(struct vme_dev *dev, int level, int statid);
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327
328The callback parameters are as follows. Care must be taken in writing a callback
329function, callback functions run in interrupt context:
330
331 void callback(int level, int statid, void *priv);
332
333
334Interrupt Generation
335--------------------
336
337The following function can be used to generate a VME interrupt at a given VME
338level and VME status ID:
339
8f966dc4 340 int vme_irq_generate(struct vme_dev *dev, int level, int statid);
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341
342
343Location monitors
344=================
345
346The VME API provides the following functionality to configure the location
347monitor.
348
349
350Location Monitor Management
351---------------------------
352
353The following functions are provided to request the use of a block of location
354monitors and to free them after they are no longer required:
355
8f966dc4 356 struct vme_resource * vme_lm_request(struct vme_dev *dev);
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357
358 void vme_lm_free(struct vme_resource * res);
359
360Each block may provide a number of location monitors, monitoring adjacent
361locations. The following function can be used to determine how many locations
362are provided:
363
364 int vme_lm_count(struct vme_resource * res);
365
366
367Location Monitor Configuration
368------------------------------
369
370Once a bank of location monitors has been allocated, the following functions
371are provided to configure the location and mode of the location monitor:
372
373 int vme_lm_set(struct vme_resource *res, unsigned long long base,
6af04b06 374 u32 aspace, u32 cycle);
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375
376 int vme_lm_get(struct vme_resource *res, unsigned long long *base,
6af04b06 377 u32 *aspace, u32 *cycle);
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378
379
380Location Monitor Use
381--------------------
382
383The following functions allow a callback to be attached and detached from each
384location monitor location. Each location monitor can monitor a number of
385adjacent locations:
386
387 int vme_lm_attach(struct vme_resource *res, int num,
388 void (*callback)(int));
389
390 int vme_lm_detach(struct vme_resource *res, int num);
391
392The callback function is declared as follows.
393
394 void callback(int num);
395
396
397Slot Detection
398==============
399
400This function returns the slot ID of the provided bridge.
401
d7729f0f 402 int vme_slot_num(struct vme_dev *dev);
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403
404
405Bus Detection
406=============
407
408This function returns the bus ID of the provided bridge.
409
410 int vme_bus_num(struct vme_dev *dev);
411
412