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Based on kernel version 3.9. Page generated on 2013-05-02 23:16 EST.

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