Documentation/scsi/53c700.txt

   1 General Description
   2 ===================
   3
   4 This driver supports the 53c700 and 53c700-66 chips.  It also supports
   5 the 53c710 but only in 53c700 emulation mode.  It is full featured and
   6 does sync (-66 and 710 only), disconnects and tag command queueing.
   7
   8 Since the 53c700 must be interfaced to a bus, you need to wrapper the
   9 card detector around this driver.  For an example, see the
  10 NCR_D700.[ch] or lasi700.[ch] files.
  11
  12 The comments in the 53c700.[ch] files tell you which parts you need to
  13 fill in to get the driver working.
  14
  15
  16 Compile Time Flags
  17 ==================
  18
  19 A compile time flag is:
  20
  21 CONFIG_53C700_LE_ON_BE
  22
  23 define if the chipset must be supported in little endian mode on a big
  24 endian architecture (used for the 700 on parisc).
  25
  26
  27 Using the Chip Core Driver
  28 ==========================
  29
  30 In order to plumb the 53c700 chip core driver into a working SCSI
  31 driver, you need to know three things about the way the chip is wired
  32 into your system (or expansion card).
  33
  34 1. The clock speed of the SCSI core
  35 2. The interrupt line used
  36 3. The memory (or io space) location of the 53c700 registers.
  37
  38 Optionally, you may also need to know other things, like how to read
  39 the SCSI Id from the card bios or whether the chip is wired for
  40 differential operation.
  41
  42 Usually you can find items 2. and 3. from general spec. documents or
  43 even by examining the configuration of a working driver under another
  44 operating system.
  45
  46 The clock speed is usually buried deep in the technical literature.
  47 It is required because it is used to set up both the synchronous and
  48 asynchronous dividers for the chip.  As a general rule of thumb,
  49 manufacturers set the clock speed at the lowest possible setting
  50 consistent with the best operation of the chip (although some choose
  51 to drive it off the CPU or bus clock rather than going to the expense
  52 of an extra clock chip).  The best operation clock speeds are:
  53
  54 53c700 - 25MHz
  55 53c700-66 - 50MHz
  56 53c710 - 40Mhz
  57
  58 Writing Your Glue Driver
  59 ========================
  60
  61 This will be a standard SCSI driver (I don't know of a good document
  62 describing this, just copy from some other driver) with at least a
  63 detect and release entry.
  64
  65 In the detect routine, you need to allocate a struct
  66 NCR_700_Host_Parameters sized memory area and clear it (so that the
  67 default values for everything are 0).  Then you must fill in the
  68 parameters that matter to you (see below), plumb the NCR_700_intr
  69 routine into the interrupt line and call NCR_700_detect with the host
  70 template and the new parameters as arguments.  You should also call
  71 the relevant request_*_region function and place the register base
  72 address into the `base' pointer of the host parameters.
  73
  74 In the release routine, you must free the NCR_700_Host_Parameters that
  75 you allocated, call the corresponding release_*_region and free the
  76 interrupt.
  77
  78 Handling Interrupts
  79 -------------------
  80
  81 In general, you should just plumb the card's interrupt line in with
  82
  83 request_irq(irq, NCR_700_intr, <irq flags>, <driver name>, host);
  84
  85 where host is the return from the relevant NCR_700_detect() routine.
  86
  87 You may also write your own interrupt handling routine which calls
  88 NCR_700_intr() directly.  However, you should only really do this if
  89 you have a card with more than one chip on it and you can read a
  90 register to tell which set of chips wants the interrupt.
  91
  92 Settable NCR_700_Host_Parameters
  93 --------------------------------
  94
  95 The following are a list of the user settable parameters:
  96
  97 clock: (MANDATORY)
  98
  99 Set to the clock speed of the chip in MHz.
 100
 101 base: (MANDATORY)
 102
 103 set to the base of the io or mem region for the register set. On 64
 104 bit architectures this is only 32 bits wide, so the registers must be
 105 mapped into the low 32 bits of memory.
 106
 107 pci_dev: (OPTIONAL)
 108
 109 set to the PCI board device.  Leave NULL for a non-pci board.  This is
 110 used for the pci_alloc_consistent() and pci_map_*() functions.
 111
 112 dmode_extra: (OPTIONAL, 53c710 only)
 113
 114 extra flags for the DMODE register.  These are used to control bus
 115 output pins on the 710.  The settings should be a combination of
 116 DMODE_FC1 and DMODE_FC2.  What these pins actually do is entirely up
 117 to the board designer.  Usually it is safe to ignore this setting.
 118
 119 differential: (OPTIONAL)
 120
 121 set to 1 if the chip drives a differential bus.
 122
 123 force_le_on_be: (OPTIONAL, only if CONFIG_53C700_LE_ON_BE is set)
 124
 125 set to 1 if the chip is operating in little endian mode on a big
 126 endian architecture.
 127
 128 chip710: (OPTIONAL)
 129
 130 set to 1 if the chip is a 53c710.
 131
 132 burst_disable: (OPTIONAL, 53c710 only)
 133
 134 disable 8 byte bursting for DMA transfers.
 135