FLASH-1100(3) (SA1100) FLASH-1100(3)
NAME
flash1100 - flash memory (StrongARM)
SYNOPSYS
bind -a '#W' /dev
/dev/flashnall
/dev/flashnctl
/dev/flashnpartition
/dev/flashnstat
DESCRIPTION
The StrongARM SA1100 kernel currently has a different flash
memory driver than some of the other ports; see BUGS below.
The flash memory device serves a one-level directory, giving
access to four files for each physical flash device, start-
ing at n=0:
flashnall
This file represents the entire flash memory.
flashnpartition
This file represents the space allocated in flash for
the flash partition table.
flashnstat
This file can be read for information about the flash
memory and the corresponding partition table (if any);
see below for details.
flashnctl
This writable file accepts a single message sync, which
flushes all buffered writes to flash.
The first line read from the status file describes the flash
chips:
man-id dev-id width sector-size total-size man-name
dev-name
where man-id and dev-id are the values (in hex) of the
chip's manufacturer and device IDs; width is the width in
bytes across the bus; sector-size is the total flash sector
size (erase unit size) in bytes, allowing for the bus width;
total-size is the total flash size in bytes; and man-name
and dev-name are character strings identifying the flash
type. Following lines give flash protection status in the
following form:
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FLASH-1100(3) (SA1100) FLASH-1100(3)
start-end:prot
where each line tells the start and end addresses of a
region, and a bit mask telling its protection status.
Finally, there is one line for each partition, including the
standard partitions all and partition, of the form:
start length checksum name
giving the starting address, length and checksum (all in
hex), and partition name.
Each partition file provides read and write access to the
bytes in the corresponding region of flash memory. Bytes
can be read and written on any byte boundary: the interface
hides any alignment restrictions. A read returns the value
of the bytes at the current file offset. A write reprograms
the flash at the current file offset to the given byte val-
ues, using the physical device's reprogramming algorithm.
The driver uses an internal buffer in system memory to hide
any erasing of flash sectors that might be required to
reprogram the given region; it also buffers the data written
so that a section is erased and reprogrammed only when
either a subsequent write moves out of the buffer or an
internal timer causes the data to be flushed to flash.
SOURCE
/os/sa1100/devflash.c
SEE ALSO
sboot(10.8)
DIAGNOSTICS
A write will return an error if the flash memory fails to be
programmed correctly.
BUGS
The flash cannot be written if the kernel is executing
directly from flash, because the physical flash cannot be
read during programming.
The buffering of writes is intended to allow the flash to be
accessed in the same way as a disc, but it has disadvan-
tages: it creates a window during which data will be lost or
corrupted if power is lost or the operation is interrupted
in some other way; erase is more frequent; and it fails to
spread the erase load evenly across the device.
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