1General Description
  2===================
  3
  4This driver supports the 53c700 and 53c700-66 chips.  It also supports
  5the 53c710 but only in 53c700 emulation mode.  It is full featured and
  6does sync (-66 and 710 only), disconnects and tag command queueing.
  7
  8Since the 53c700 must be interfaced to a bus, you need to wrapper the
  9card detector around this driver.  For an example, see the
 10NCR_D700.[ch] or lasi700.[ch] files.
 11
 12The comments in the 53c700.[ch] files tell you which parts you need to
 13fill in to get the driver working.
 14
 15
 16Compile Time Flags
 17==================
 18
 19A compile time flag is:
 20
 21CONFIG_53C700_LE_ON_BE
 22
 23define if the chipset must be supported in little endian mode on a big
 24endian architecture (used for the 700 on parisc).
 25
 26
 27Using the Chip Core Driver
 28==========================
 29
 30In order to plumb the 53c700 chip core driver into a working SCSI
 31driver, you need to know three things about the way the chip is wired
 32into your system (or expansion card).
 33
 341. The clock speed of the SCSI core
 352. The interrupt line used
 363. The memory (or io space) location of the 53c700 registers.
 37
 38Optionally, you may also need to know other things, like how to read
 39the SCSI Id from the card bios or whether the chip is wired for
 40differential operation.
 41
 42Usually you can find items 2. and 3. from general spec. documents or
 43even by examining the configuration of a working driver under another
 44operating system.
 45
 46The clock speed is usually buried deep in the technical literature.
 47It is required because it is used to set up both the synchronous and
 48asynchronous dividers for the chip.  As a general rule of thumb,
 49manufacturers set the clock speed at the lowest possible setting
 50consistent with the best operation of the chip (although some choose
 51to drive it off the CPU or bus clock rather than going to the expense
 52of an extra clock chip).  The best operation clock speeds are:
 53
 5453c700 - 25MHz
 5553c700-66 - 50MHz
 5653c710 - 40Mhz
 57
 58Writing Your Glue Driver
 59========================
 60
 61This will be a standard SCSI driver (I don't know of a good document
 62describing this, just copy from some other driver) with at least a
 63detect and release entry.
 64
 65In the detect routine, you need to allocate a struct
 66NCR_700_Host_Parameters sized memory area and clear it (so that the
 67default values for everything are 0).  Then you must fill in the
 68parameters that matter to you (see below), plumb the NCR_700_intr
 69routine into the interrupt line and call NCR_700_detect with the host
 70template and the new parameters as arguments.  You should also call
 71the relevant request_*_region function and place the register base
 72address into the `base' pointer of the host parameters.
 73
 74In the release routine, you must free the NCR_700_Host_Parameters that
 75you allocated, call the corresponding release_*_region and free the
 76interrupt.
 77
 78Handling Interrupts
 79-------------------
 80
 81In general, you should just plumb the card's interrupt line in with 
 82
 83request_irq(irq, NCR_700_intr, <irq flags>, <driver name>, host);
 84
 85where host is the return from the relevant NCR_700_detect() routine.
 86
 87You may also write your own interrupt handling routine which calls
 88NCR_700_intr() directly.  However, you should only really do this if
 89you have a card with more than one chip on it and you can read a
 90register to tell which set of chips wants the interrupt.
 91
 92Settable NCR_700_Host_Parameters
 93--------------------------------
 94
 95The following are a list of the user settable parameters:
 96
 97clock: (MANDATORY)
 98
 99Set to the clock speed of the chip in MHz.
100
101base: (MANDATORY)
102
103set to the base of the io or mem region for the register set. On 64
104bit architectures this is only 32 bits wide, so the registers must be
105mapped into the low 32 bits of memory.
106
107pci_dev: (OPTIONAL)
108
109set to the PCI board device.  Leave NULL for a non-pci board.  This is
110used for the pci_alloc_consistent() and pci_map_*() functions.
111
112dmode_extra: (OPTIONAL, 53c710 only)
113
114extra flags for the DMODE register.  These are used to control bus
115output pins on the 710.  The settings should be a combination of
116DMODE_FC1 and DMODE_FC2.  What these pins actually do is entirely up
117to the board designer.  Usually it is safe to ignore this setting.
118
119differential: (OPTIONAL)
120
121set to 1 if the chip drives a differential bus.
122
123force_le_on_be: (OPTIONAL, only if CONFIG_53C700_LE_ON_BE is set)
124
125set to 1 if the chip is operating in little endian mode on a big
126endian architecture.
127
128chip710: (OPTIONAL)
129
130set to 1 if the chip is a 53c710.
131
132burst_disable: (OPTIONAL, 53c710 only)
133
134disable 8 byte bursting for DMA transfers.
135