VME: Move API documentation to Documentation folder

The documentation for the VME device driver API is currently in
drivers/vme/vme_api.txt, move this to Documentation/vme_api.txt

Signed-of-by: Martyn Welch <martyn.welch@ge.com>
Acked-by: Rob Landley <rob@landley.net>

Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 396 insertions, 0 deletions

diff --git a/Documentation/vme_api.txt b/Documentation/vme_api.txt
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+			VME Device Driver API
+			=====================
+
+Driver registration
+===================
+
+As with other subsystems within the Linux kernel, VME device drivers register
+with the VME subsystem, typically called from the devices init routine.  This is
+achieved via a call to the following function:
+
+	int vme_register_driver (struct vme_driver *driver);
+
+If driver registration is successful this function returns zero, if an error
+occurred a negative error code will be returned.
+
+A pointer to a structure of type 'vme_driver' must be provided to the
+registration function. The structure is as follows:
+
+	struct vme_driver {
+		struct list_head node;
+		const char *name;
+		int (*match)(struct vme_dev *);
+		int (*probe)(struct vme_dev *);
+		int (*remove)(struct vme_dev *);
+		void (*shutdown)(void);
+		struct device_driver driver;
+		struct list_head devices;
+		unsigned int ndev;
+	};
+
+At the minimum, the '.name', '.match' and '.probe' elements of this structure
+should be correctly set. The '.name' element is a pointer to a string holding
+the device driver's name.
+
+The '.match' function allows controlling the number of devices that need to
+be registered. The match function should return 1 if a device should be
+probed and 0 otherwise. This example match function (from vme_user.c) limits
+the number of devices probed to one:
+
+	#define USER_BUS_MAX	1
+	...
+	static int vme_user_match(struct vme_dev *vdev)
+	{
+		if (vdev->id.num >= USER_BUS_MAX)
+			return 0;
+		return 1;
+	}
+
+The '.probe' element should contain a pointer to the probe routine. The
+probe routine is passed a 'struct vme_dev' pointer as an argument. The
+'struct vme_dev' structure looks like the following:
+
+	struct vme_dev {
+		int num;
+		struct vme_bridge *bridge;
+		struct device dev;
+		struct list_head drv_list;
+		struct list_head bridge_list;
+	};
+
+Here, the 'num' field refers to the sequential device ID for this specific
+driver. The bridge number (or bus number) can be accessed using
+dev->bridge->num.
+
+A function is also provided to unregister the driver from the VME core and is
+usually called from the device driver's exit routine:
+
+	void vme_unregister_driver (struct vme_driver *driver);
+
+
+Resource management
+===================
+
+Once a driver has registered with the VME core the provided match routine will
+be called the number of times specified during the registration. If a match
+succeeds, a non-zero value should be returned. A zero return value indicates
+failure. For all successful matches, the probe routine of the corresponding
+driver is called. The probe routine is passed a pointer to the devices
+device structure. This pointer should be saved, it will be required for
+requesting VME resources.
+
+The driver can request ownership of one or more master windows, slave windows
+and/or dma channels. Rather than allowing the device driver to request a
+specific window or DMA channel (which may be used by a different driver) this
+driver allows a resource to be assigned based on the required attributes of the
+driver in question:
+
+	struct vme_resource * vme_master_request(struct vme_dev *dev,
+		u32 aspace, u32 cycle, u32 width);
+
+	struct vme_resource * vme_slave_request(struct vme_dev *dev, u32 aspace,
+		u32 cycle);
+
+	struct vme_resource *vme_dma_request(struct vme_dev *dev, u32 route);
+
+For slave windows these attributes are split into the VME address spaces that
+need to be accessed in 'aspace' and VME bus cycle types required in 'cycle'.
+Master windows add a further set of attributes in 'width' specifying the
+required data transfer widths. These attributes are defined as bitmasks and as
+such any combination of the attributes can be requested for a single window,
+the core will assign a window that meets the requirements, returning a pointer
+of type vme_resource that should be used to identify the allocated resource
+when it is used. For DMA controllers, the request function requires the
+potential direction of any transfers to be provided in the route attributes.
+This is typically VME-to-MEM and/or MEM-to-VME, though some hardware can
+support VME-to-VME and MEM-to-MEM transfers as well as test pattern generation.
+If an unallocated window fitting the requirements can not be found a NULL
+pointer will be returned.
+
+Functions are also provided to free window allocations once they are no longer
+required. These functions should be passed the pointer to the resource provided
+during resource allocation:
+
+	void vme_master_free(struct vme_resource *res);
+
+	void vme_slave_free(struct vme_resource *res);
+
+	void vme_dma_free(struct vme_resource *res);
+
+
+Master windows
+==============
+
+Master windows provide access from the local processor[s] out onto the VME bus.
+The number of windows available and the available access modes is dependent on
+the underlying chipset. A window must be configured before it can be used.
+
+
+Master window configuration
+---------------------------
+
+Once a master window has been assigned the following functions can be used to
+configure it and retrieve the current settings:
+
+	int vme_master_set (struct vme_resource *res, int enabled,
+		unsigned long long base, unsigned long long size, u32 aspace,
+		u32 cycle, u32 width);
+
+	int vme_master_get (struct vme_resource *res, int *enabled,
+		unsigned long long *base, unsigned long long *size, u32 *aspace,
+		u32 *cycle, u32 *width);
+
+The address spaces, transfer widths and cycle types are the same as described
+under resource management, however some of the options are mutually exclusive.
+For example, only one address space may be specified.
+
+These functions return 0 on success or an error code should the call fail.
+
+
+Master window access
+--------------------
+
+The following functions can be used to read from and write to configured master
+windows. These functions return the number of bytes copied:
+
+	ssize_t vme_master_read(struct vme_resource *res, void *buf,
+		size_t count, loff_t offset);
+
+	ssize_t vme_master_write(struct vme_resource *res, void *buf,
+		size_t count, loff_t offset);
+
+In addition to simple reads and writes, a function is provided to do a
+read-modify-write transaction. This function returns the original value of the
+VME bus location :
+
+	unsigned int vme_master_rmw (struct vme_resource *res,
+		unsigned int mask, unsigned int compare, unsigned int swap,
+		loff_t offset);
+
+This functions by reading the offset, applying the mask. If the bits selected in
+the mask match with the values of the corresponding bits in the compare field,
+the value of swap is written the specified offset.
+
+
+Slave windows
+=============
+
+Slave windows provide devices on the VME bus access into mapped portions of the
+local memory. The number of windows available and the access modes that can be
+used is dependent on the underlying chipset. A window must be configured before
+it can be used.
+
+
+Slave window configuration
+--------------------------
+
+Once a slave window has been assigned the following functions can be used to
+configure it and retrieve the current settings:
+
+	int vme_slave_set (struct vme_resource *res, int enabled,
+		unsigned long long base, unsigned long long size,
+		dma_addr_t mem, u32 aspace, u32 cycle);
+
+	int vme_slave_get (struct vme_resource *res, int *enabled,
+		unsigned long long *base, unsigned long long *size,
+		dma_addr_t *mem, u32 *aspace, u32 *cycle);
+
+The address spaces, transfer widths and cycle types are the same as described
+under resource management, however some of the options are mutually exclusive.
+For example, only one address space may be specified.
+
+These functions return 0 on success or an error code should the call fail.
+
+
+Slave window buffer allocation
+------------------------------
+
+Functions are provided to allow the user to allocate and free a contiguous
+buffers which will be accessible by the VME bridge. These functions do not have
+to be used, other methods can be used to allocate a buffer, though care must be
+taken to ensure that they are contiguous and accessible by the VME bridge:
+
+	void * vme_alloc_consistent(struct vme_resource *res, size_t size,
+		dma_addr_t *mem);
+
+	void vme_free_consistent(struct vme_resource *res, size_t size,
+		void *virt,	dma_addr_t mem);
+
+
+Slave window access
+-------------------
+
+Slave windows map local memory onto the VME bus, the standard methods for
+accessing memory should be used.
+
+
+DMA channels
+============
+
+The VME DMA transfer provides the ability to run link-list DMA transfers. The
+API introduces the concept of DMA lists. Each DMA list is a link-list which can
+be passed to a DMA controller. Multiple lists can be created, extended,
+executed, reused and destroyed.
+
+
+List Management
+---------------
+
+The following functions are provided to create and destroy DMA lists. Execution
+of a list will not automatically destroy the list, thus enabling a list to be
+reused for repetitive tasks:
+
+	struct vme_dma_list *vme_new_dma_list(struct vme_resource *res);
+
+	int vme_dma_list_free(struct vme_dma_list *list);
+
+
+List Population
+---------------
+
+An item can be added to a list using the following function ( the source and
+destination attributes need to be created before calling this function, this is
+covered under "Transfer Attributes"):
+
+	int vme_dma_list_add(struct vme_dma_list *list,
+		struct vme_dma_attr *src, struct vme_dma_attr *dest,
+		size_t count);
+
+NOTE:	The detailed attributes of the transfers source and destination
+	are not checked until an entry is added to a DMA list, the request
+	for a DMA channel purely checks the directions in which the
+	controller is expected to transfer data. As a result it is
+	possible for this call to return an error, for example if the
+	source or destination is in an unsupported VME address space.
+
+Transfer Attributes
+-------------------
+
+The attributes for the source and destination are handled separately from adding
+an item to a list. This is due to the diverse attributes required for each type
+of source and destination. There are functions to create attributes for PCI, VME
+and pattern sources and destinations (where appropriate):
+
+Pattern source:
+
+	struct vme_dma_attr *vme_dma_pattern_attribute(u32 pattern, u32 type);
+
+PCI source or destination:
+
+	struct vme_dma_attr *vme_dma_pci_attribute(dma_addr_t mem);
+
+VME source or destination:
+
+	struct vme_dma_attr *vme_dma_vme_attribute(unsigned long long base,
+		u32 aspace, u32 cycle, u32 width);
+
+The following function should be used to free an attribute:
+
+	void vme_dma_free_attribute(struct vme_dma_attr *attr);
+
+
+List Execution
+--------------
+
+The following function queues a list for execution. The function will return
+once the list has been executed:
+
+	int vme_dma_list_exec(struct vme_dma_list *list);
+
+
+Interrupts
+==========
+
+The VME API provides functions to attach and detach callbacks to specific VME
+level and status ID combinations and for the generation of VME interrupts with
+specific VME level and status IDs.
+
+
+Attaching Interrupt Handlers
+----------------------------
+
+The following functions can be used to attach and free a specific VME level and
+status ID combination. Any given combination can only be assigned a single
+callback function. A void pointer parameter is provided, the value of which is
+passed to the callback function, the use of this pointer is user undefined:
+
+	int vme_irq_request(struct vme_dev *dev, int level, int statid,
+		void (*callback)(int, int, void *), void *priv);
+
+	void vme_irq_free(struct vme_dev *dev, int level, int statid);
+
+The callback parameters are as follows. Care must be taken in writing a callback
+function, callback functions run in interrupt context:
+
+	void callback(int level, int statid, void *priv);
+
+
+Interrupt Generation
+--------------------
+
+The following function can be used to generate a VME interrupt at a given VME
+level and VME status ID:
+
+	int vme_irq_generate(struct vme_dev *dev, int level, int statid);
+
+
+Location monitors
+=================
+
+The VME API provides the following functionality to configure the location
+monitor.
+
+
+Location Monitor Management
+---------------------------
+
+The following functions are provided to request the use of a block of location
+monitors and to free them after they are no longer required:
+
+	struct vme_resource * vme_lm_request(struct vme_dev *dev);
+
+	void vme_lm_free(struct vme_resource * res);
+
+Each block may provide a number of location monitors, monitoring adjacent
+locations. The following function can be used to determine how many locations
+are provided:
+
+	int vme_lm_count(struct vme_resource * res);
+
+
+Location Monitor Configuration
+------------------------------
+
+Once a bank of location monitors has been allocated, the following functions
+are provided to configure the location and mode of the location monitor:
+
+	int vme_lm_set(struct vme_resource *res, unsigned long long base,
+		u32 aspace, u32 cycle);
+
+	int vme_lm_get(struct vme_resource *res, unsigned long long *base,
+		u32 *aspace, u32 *cycle);
+
+
+Location Monitor Use
+--------------------
+
+The following functions allow a callback to be attached and detached from each
+location monitor location. Each location monitor can monitor a number of
+adjacent locations:
+
+	int vme_lm_attach(struct vme_resource *res, int num,
+		void (*callback)(int));
+
+	int vme_lm_detach(struct vme_resource *res, int num);
+
+The callback function is declared as follows.
+
+	void callback(int num);
+
+
+Slot Detection
+==============
+
+This function returns the slot ID of the provided bridge.
+
+	int vme_slot_get(struct vme_dev *dev);