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author | Linus Torvalds <torvalds@ppc970.osdl.org> | 2005-04-17 02:20:36 +0400 |
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committer | Linus Torvalds <torvalds@ppc970.osdl.org> | 2005-04-17 02:20:36 +0400 |
commit | 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (patch) | |
tree | 0bba044c4ce775e45a88a51686b5d9f90697ea9d /Documentation/scsi/53c700.txt | |
download | linux-1da177e4c3f41524e886b7f1b8a0c1fc7321cac2.tar.xz |
Linux-2.6.12-rc2
Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.
Let it rip!
Diffstat (limited to 'Documentation/scsi/53c700.txt')
-rw-r--r-- | Documentation/scsi/53c700.txt | 154 |
1 files changed, 154 insertions, 0 deletions
diff --git a/Documentation/scsi/53c700.txt b/Documentation/scsi/53c700.txt new file mode 100644 index 000000000000..0da681d497a2 --- /dev/null +++ b/Documentation/scsi/53c700.txt @@ -0,0 +1,154 @@ +General Description +=================== + +This driver supports the 53c700 and 53c700-66 chips. It also supports +the 53c710 but only in 53c700 emulation mode. It is full featured and +does sync (-66 and 710 only), disconnects and tag command queueing. + +Since the 53c700 must be interfaced to a bus, you need to wrapper the +card detector around this driver. For an example, see the +NCR_D700.[ch] or lasi700.[ch] files. + +The comments in the 53c700.[ch] files tell you which parts you need to +fill in to get the driver working. + + +Compile Time Flags +================== + +The driver may be either io mapped or memory mapped. This is +selectable by configuration flags: + +CONFIG_53C700_MEM_MAPPED + +define if the driver is memory mapped. + +CONFIG_53C700_IO_MAPPED + +define if the driver is to be io mapped. + +One or other of the above flags *must* be defined. + +Other flags are: + +CONFIG_53C700_LE_ON_BE + +define if the chipset must be supported in little endian mode on a big +endian architecture (used for the 700 on parisc). + +CONFIG_53C700_USE_CONSISTENT + +allocate consistent memory (should only be used if your architecture +has a mixture of consistent and inconsistent memory). Fully +consistent or fully inconsistent architectures should not define this. + + +Using the Chip Core Driver +========================== + +In order to plumb the 53c700 chip core driver into a working SCSI +driver, you need to know three things about the way the chip is wired +into your system (or expansion card). + +1. The clock speed of the SCSI core +2. The interrupt line used +3. The memory (or io space) location of the 53c700 registers. + +Optionally, you may also need to know other things, like how to read +the SCSI Id from the card bios or whether the chip is wired for +differential operation. + +Usually you can find items 2. and 3. from general spec. documents or +even by examining the configuration of a working driver under another +operating system. + +The clock speed is usually buried deep in the technical literature. +It is required because it is used to set up both the synchronous and +asynchronous dividers for the chip. As a general rule of thumb, +manufacturers set the clock speed at the lowest possible setting +consistent with the best operation of the chip (although some choose +to drive it off the CPU or bus clock rather than going to the expense +of an extra clock chip). The best operation clock speeds are: + +53c700 - 25MHz +53c700-66 - 50MHz +53c710 - 40Mhz + +Writing Your Glue Driver +======================== + +This will be a standard SCSI driver (I don't know of a good document +describing this, just copy from some other driver) with at least a +detect and release entry. + +In the detect routine, you need to allocate a struct +NCR_700_Host_Parameters sized memory area and clear it (so that the +default values for everything are 0). Then you must fill in the +parameters that matter to you (see below), plumb the NCR_700_intr +routine into the interrupt line and call NCR_700_detect with the host +template and the new parameters as arguments. You should also call +the relevant request_*_region function and place the register base +address into the `base' pointer of the host parameters. + +In the release routine, you must free the NCR_700_Host_Parameters that +you allocated, call the corresponding release_*_region and free the +interrupt. + +Handling Interrupts +------------------- + +In general, you should just plumb the card's interrupt line in with + +request_irq(irq, NCR_700_intr, <irq flags>, <driver name>, host); + +where host is the return from the relevant NCR_700_detect() routine. + +You may also write your own interrupt handling routine which calls +NCR_700_intr() directly. However, you should only really do this if +you have a card with more than one chip on it and you can read a +register to tell which set of chips wants the interrupt. + +Settable NCR_700_Host_Parameters +-------------------------------- + +The following are a list of the user settable parameters: + +clock: (MANDATORY) + +Set to the clock speed of the chip in MHz. + +base: (MANDATORY) + +set to the base of the io or mem region for the register set. On 64 +bit architectures this is only 32 bits wide, so the registers must be +mapped into the low 32 bits of memory. + +pci_dev: (OPTIONAL) + +set to the PCI board device. Leave NULL for a non-pci board. This is +used for the pci_alloc_consistent() and pci_map_*() functions. + +dmode_extra: (OPTIONAL, 53c710 only) + +extra flags for the DMODE register. These are used to control bus +output pins on the 710. The settings should be a combination of +DMODE_FC1 and DMODE_FC2. What these pins actually do is entirely up +to the board designer. Usually it is safe to ignore this setting. + +differential: (OPTIONAL) + +set to 1 if the chip drives a differential bus. + +force_le_on_be: (OPTIONAL, only if CONFIG_53C700_LE_ON_BE is set) + +set to 1 if the chip is operating in little endian mode on a big +endian architecture. + +chip710: (OPTIONAL) + +set to 1 if the chip is a 53c710. + +burst_disable: (OPTIONAL, 53c710 only) + +disable 8 byte bursting for DMA transfers. + |