mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-10-28 23:24:50 +00:00
d7729f0fc4
Traditionally the "get" functions increment the reference count of the object that is returned, which does not happen with vme_slot_get. The function vme_slot_get returns the physical VME slot associated with a particular struct vme_dev. Rename vme_slot_num to avoid any confusion. Signed-off-by: Martyn Welch <martyn.welch@ge.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
406 lines
13 KiB
Text
406 lines
13 KiB
Text
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_num(struct vme_dev *dev);
|
|
|
|
|
|
Bus Detection
|
|
=============
|
|
|
|
This function returns the bus ID of the provided bridge.
|
|
|
|
int vme_bus_num(struct vme_dev *dev);
|
|
|
|
|