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Diffstat (limited to 'drivers/vme/vme_api.txt')
| -rw-r--r-- | drivers/vme/vme_api.txt | 396 |
1 files changed, 0 insertions, 396 deletions
diff --git a/drivers/vme/vme_api.txt b/drivers/vme/vme_api.txt deleted file mode 100644 index 856efa35f6e3..000000000000 --- a/drivers/vme/vme_api.txt +++ /dev/null @@ -1,396 +0,0 @@ - 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); |