About Kernel Documentation Linux Kernel Contact Linux Resources Linux Blog

Documentation / scsi / 53c700.txt

Based on kernel version 2.6.26. Page generated on 2008-07-16 21:13 EST.

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	The driver may be either io mapped or memory mapped.  This is
20	selectable by configuration flags:
21	
22	CONFIG_53C700_MEM_MAPPED
23	
24	define if the driver is memory mapped.
25	
26	CONFIG_53C700_IO_MAPPED
27	
28	define if the driver is to be io mapped.
29	
30	One or other of the above flags *must* be defined.
31	
32	Other flags are:
33	
34	CONFIG_53C700_LE_ON_BE
35	
36	define if the chipset must be supported in little endian mode on a big
37	endian architecture (used for the 700 on parisc).
38	
39	CONFIG_53C700_USE_CONSISTENT
40	
41	allocate consistent memory (should only be used if your architecture
42	has a mixture of consistent and inconsistent memory).  Fully
43	consistent or fully inconsistent architectures should not define this.
44	
45	
46	Using the Chip Core Driver
47	==========================
48	
49	In order to plumb the 53c700 chip core driver into a working SCSI
50	driver, you need to know three things about the way the chip is wired
51	into your system (or expansion card).
52	
53	1. The clock speed of the SCSI core
54	2. The interrupt line used
55	3. The memory (or io space) location of the 53c700 registers.
56	
57	Optionally, you may also need to know other things, like how to read
58	the SCSI Id from the card bios or whether the chip is wired for
59	differential operation.
60	
61	Usually you can find items 2. and 3. from general spec. documents or
62	even by examining the configuration of a working driver under another
63	operating system.
64	
65	The clock speed is usually buried deep in the technical literature.
66	It is required because it is used to set up both the synchronous and
67	asynchronous dividers for the chip.  As a general rule of thumb,
68	manufacturers set the clock speed at the lowest possible setting
69	consistent with the best operation of the chip (although some choose
70	to drive it off the CPU or bus clock rather than going to the expense
71	of an extra clock chip).  The best operation clock speeds are:
72	
73	53c700 - 25MHz
74	53c700-66 - 50MHz
75	53c710 - 40Mhz
76	
77	Writing Your Glue Driver
78	========================
79	
80	This will be a standard SCSI driver (I don't know of a good document
81	describing this, just copy from some other driver) with at least a
82	detect and release entry.
83	
84	In the detect routine, you need to allocate a struct
85	NCR_700_Host_Parameters sized memory area and clear it (so that the
86	default values for everything are 0).  Then you must fill in the
87	parameters that matter to you (see below), plumb the NCR_700_intr
88	routine into the interrupt line and call NCR_700_detect with the host
89	template and the new parameters as arguments.  You should also call
90	the relevant request_*_region function and place the register base
91	address into the `base' pointer of the host parameters.
92	
93	In the release routine, you must free the NCR_700_Host_Parameters that
94	you allocated, call the corresponding release_*_region and free the
95	interrupt.
96	
97	Handling Interrupts
98	-------------------
99	
100	In general, you should just plumb the card's interrupt line in with 
101	
102	request_irq(irq, NCR_700_intr, <irq flags>, <driver name>, host);
103	
104	where host is the return from the relevant NCR_700_detect() routine.
105	
106	You may also write your own interrupt handling routine which calls
107	NCR_700_intr() directly.  However, you should only really do this if
108	you have a card with more than one chip on it and you can read a
109	register to tell which set of chips wants the interrupt.
110	
111	Settable NCR_700_Host_Parameters
112	--------------------------------
113	
114	The following are a list of the user settable parameters:
115	
116	clock: (MANDATORY)
117	
118	Set to the clock speed of the chip in MHz.
119	
120	base: (MANDATORY)
121	
122	set to the base of the io or mem region for the register set. On 64
123	bit architectures this is only 32 bits wide, so the registers must be
124	mapped into the low 32 bits of memory.
125	
126	pci_dev: (OPTIONAL)
127	
128	set to the PCI board device.  Leave NULL for a non-pci board.  This is
129	used for the pci_alloc_consistent() and pci_map_*() functions.
130	
131	dmode_extra: (OPTIONAL, 53c710 only)
132	
133	extra flags for the DMODE register.  These are used to control bus
134	output pins on the 710.  The settings should be a combination of
135	DMODE_FC1 and DMODE_FC2.  What these pins actually do is entirely up
136	to the board designer.  Usually it is safe to ignore this setting.
137	
138	differential: (OPTIONAL)
139	
140	set to 1 if the chip drives a differential bus.
141	
142	force_le_on_be: (OPTIONAL, only if CONFIG_53C700_LE_ON_BE is set)
143	
144	set to 1 if the chip is operating in little endian mode on a big
145	endian architecture.
146	
147	chip710: (OPTIONAL)
148	
149	set to 1 if the chip is a 53c710.
150	
151	burst_disable: (OPTIONAL, 53c710 only)
152	
153	disable 8 byte bursting for DMA transfers.
Hide Line Numbers
About Kernel Documentation Linux Kernel Contact Linux Resources Linux Blog

Information is copyright its respective author. All material is available from the Linux Kernel Source distributed under a GPL License. This page is provided as a free service by mjmwired.net.