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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 following function:
10
11	int vme_register_driver (struct vme_driver *driver, unsigned int ndevs);
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. Along with ndevs, which is the number of devices your
18	driver is able to support. The structure is as follows:
19
20	struct vme_driver {
21	struct list_head node;
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;
30	};
31
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.
35
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
38	probed and 0 otherwise. This example match function (from vme_user.c) limits
39	the number of devices probed to one:
40
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	}
49
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:
53
54	struct vme_dev {
55	int num;
56	struct vme_bridge *bridge;
57	struct device dev;
58	struct list_head drv_list;
59	struct list_head bridge_list;
60	};
61
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.
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
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
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
89	struct vme_resource * vme_master_request(struct vme_dev *dev,
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.
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.
126	The number of windows available and the available access modes is dependent on
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,
137	unsigned long long base, unsigned long long size, u32 aspace,
138	u32 cycle, u32 width);
139
140	int vme_master_get (struct vme_resource *res, int *enabled,
141	unsigned long long *base, unsigned long long *size, u32 *aspace,
142	u32 *cycle, u32 *width);
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
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
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
187	used is dependent on the underlying chipset. A window must be configured before
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,
199	dma_addr_t mem, u32 aspace, u32 cycle);
200
201	int vme_slave_get (struct vme_resource *res, int *enabled,
202	unsigned long long *base, unsigned long long *size,
203	dma_addr_t *mem, u32 *aspace, u32 *cycle);
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
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.
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
283	struct vme_dma_attr *vme_dma_pattern_attribute(u32 pattern, u32 type);
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,
292	u32 aspace, u32 cycle, u32 width);
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
324	int vme_irq_request(struct vme_dev *dev, int level, int statid,
325	void (*callback)(int, int, void *), void *priv);
326
327	void vme_irq_free(struct vme_dev *dev, int level, int statid);
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
341	int vme_irq_generate(struct vme_dev *dev, int level, int statid);
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
357	struct vme_resource * vme_lm_request(struct vme_dev *dev);
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,
375	u32 aspace, u32 cycle);
376
377	int vme_lm_get(struct vme_resource *res, unsigned long long *base,
378	u32 *aspace, u32 *cycle);
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,
389	void (*callback)(void *));
390
391	int vme_lm_detach(struct vme_resource *res, int num);
392
393	The callback function is declared as follows.
394
395	void callback(void *data);
396
397
398	Slot Detection
399	==============
400
401	This function returns the slot ID of the provided bridge.
402
403	int vme_slot_num(struct vme_dev *dev);
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
414