Adding upstream version 6.1.76.upstream/6.1.76upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 134 insertions, 0 deletions

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+.. SPDX-License-Identifier: GPL-2.0
+
+=======================
+The 53c700 Driver Notes
+=======================
+
+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
+==================
+
+A compile time flag is::
+
+	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).
+
+
+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.