Root/Documentation/scsi/53c700.txt

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
19The driver may be either io mapped or memory mapped. This is
20selectable by configuration flags:
21
22CONFIG_53C700_MEM_MAPPED
23
24define if the driver is memory mapped.
25
26CONFIG_53C700_IO_MAPPED
27
28define if the driver is to be io mapped.
29
30One or other of the above flags *must* be defined.
31
32Other flags are:
33
34CONFIG_53C700_LE_ON_BE
35
36define if the chipset must be supported in little endian mode on a big
37endian architecture (used for the 700 on parisc).
38
39CONFIG_53C700_USE_CONSISTENT
40
41allocate consistent memory (should only be used if your architecture
42has a mixture of consistent and inconsistent memory). Fully
43consistent or fully inconsistent architectures should not define this.
44
45
46Using the Chip Core Driver
47==========================
48
49In order to plumb the 53c700 chip core driver into a working SCSI
50driver, you need to know three things about the way the chip is wired
51into your system (or expansion card).
52
531. The clock speed of the SCSI core
542. The interrupt line used
553. The memory (or io space) location of the 53c700 registers.
56
57Optionally, you may also need to know other things, like how to read
58the SCSI Id from the card bios or whether the chip is wired for
59differential operation.
60
61Usually you can find items 2. and 3. from general spec. documents or
62even by examining the configuration of a working driver under another
63operating system.
64
65The clock speed is usually buried deep in the technical literature.
66It is required because it is used to set up both the synchronous and
67asynchronous dividers for the chip. As a general rule of thumb,
68manufacturers set the clock speed at the lowest possible setting
69consistent with the best operation of the chip (although some choose
70to drive it off the CPU or bus clock rather than going to the expense
71of an extra clock chip). The best operation clock speeds are:
72
7353c700 - 25MHz
7453c700-66 - 50MHz
7553c710 - 40Mhz
76
77Writing Your Glue Driver
78========================
79
80This will be a standard SCSI driver (I don't know of a good document
81describing this, just copy from some other driver) with at least a
82detect and release entry.
83
84In the detect routine, you need to allocate a struct
85NCR_700_Host_Parameters sized memory area and clear it (so that the
86default values for everything are 0). Then you must fill in the
87parameters that matter to you (see below), plumb the NCR_700_intr
88routine into the interrupt line and call NCR_700_detect with the host
89template and the new parameters as arguments. You should also call
90the relevant request_*_region function and place the register base
91address into the `base' pointer of the host parameters.
92
93In the release routine, you must free the NCR_700_Host_Parameters that
94you allocated, call the corresponding release_*_region and free the
95interrupt.
96
97Handling Interrupts
98-------------------
99
100In general, you should just plumb the card's interrupt line in with
101
102request_irq(irq, NCR_700_intr, <irq flags>, <driver name>, host);
103
104where host is the return from the relevant NCR_700_detect() routine.
105
106You may also write your own interrupt handling routine which calls
107NCR_700_intr() directly. However, you should only really do this if
108you have a card with more than one chip on it and you can read a
109register to tell which set of chips wants the interrupt.
110
111Settable NCR_700_Host_Parameters
112--------------------------------
113
114The following are a list of the user settable parameters:
115
116clock: (MANDATORY)
117
118Set to the clock speed of the chip in MHz.
119
120base: (MANDATORY)
121
122set to the base of the io or mem region for the register set. On 64
123bit architectures this is only 32 bits wide, so the registers must be
124mapped into the low 32 bits of memory.
125
126pci_dev: (OPTIONAL)
127
128set to the PCI board device. Leave NULL for a non-pci board. This is
129used for the pci_alloc_consistent() and pci_map_*() functions.
130
131dmode_extra: (OPTIONAL, 53c710 only)
132
133extra flags for the DMODE register. These are used to control bus
134output pins on the 710. The settings should be a combination of
135DMODE_FC1 and DMODE_FC2. What these pins actually do is entirely up
136to the board designer. Usually it is safe to ignore this setting.
137
138differential: (OPTIONAL)
139
140set to 1 if the chip drives a differential bus.
141
142force_le_on_be: (OPTIONAL, only if CONFIG_53C700_LE_ON_BE is set)
143
144set to 1 if the chip is operating in little endian mode on a big
145endian architecture.
146
147chip710: (OPTIONAL)
148
149set to 1 if the chip is a 53c710.
150
151burst_disable: (OPTIONAL, 53c710 only)
152
153disable 8 byte bursting for DMA transfers.
154
155

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