Chapter 59. ST Microelectronics NANDxxxx3a chips
Table of Contents
CYGPKG_DEVS_NAND_ST_NANDXXXX3A driver package
provides support for the NANDxxxx3A chip family by ST Microelectronics.
Most users will only need to add this package to their eCos configuration and not need to interact with it further. This package provides only an inline code fragment which is intended to be instantiated by the target platform HAL and provided with appropriate board-specific low-level functions allowing it to access the hardware.
59.1.1. Using this driver in a board port
This driver's chip support is currently provided as two files:
Prototypes the low-level chip access functions required by the chip driver, declares a private struct for use by the driver and provides a
NANDXXXX3A_DEVICEmacro for convenience.
Implements high-level chip functions and exposes them via the
CYG_NAND_FUNSmacro. This file is not intended to be compiled on its own.
A platform HAL would typically make use of this driver in a single source file with the following steps:
- Declare a private struct and one or more static instances of it as appropriate,
- implement the required low-level functions,
finally, instantiate the chip with the
NANDXXXX3A_DEVICEmacro the appropriate number of times, giving each chip an appropriate name and its own private struct if need be, declaring its size, and selecting the ECC and OOB semantics to use.
For more details about the infrastructure provided by the NAND layer and the semantics it expects of the chip driver, refer to Chapter 53, eCos NAND Flash Library. An example driver instantiation can be found in the platform HAL for the STM3210E-EVAL board.
59.1.2. Memory usage note
As discussed in Section 55.2, “High-level (chip) functions”, the chip
initialisation function must set up the
pointer in the cyg_nand_device struct. This driver does so
by including pointer to a sufficiently large byte array in the
nandxxx3a_priv struct. That struct is intended to be
allocated as a static struct in the data or BSS segment (one per chip),
which avoids adding a dependency on
59.1.3. Low-level functions required from the platform HAL
These functions are prototyped in
They have no return value ("void"), except where indicated.
Writes a single command byte to the chip's command latch.
write_addrbytes(device, pointer to bytes, number of bytes)
Writes a number of address bytes in turn to the chip's address latch.
read_data_bulk(device, output pointer, number of bytes)
Reads data from the device, respectively a single byte and in bulk.
write_data_bulk(device, data pointer, number of bytes)
Writes data to the device, respectively a single byte and in bulk.
wait_ready_or_time(device, initial delay, fallback time)
Wait for the chip to signal READY or, if this line is not available, fall back to a worst-case time delay (measured in microseconds).
Wait for the chip to signal READY or, if this line is not available, enter a loop waiting for its Status register (ANDed with the given mask) to be non-zero.
Hooks for any board-specific locking which may be required in addition to the NAND library's chip-level locking. (This would be useful if, for example, access to multiple chips was mediated by a single set of GPIO lines which ought not to be invoked concurrently.)
Board-level platform initialisation hook. This is called very early on in the chip initialisation routine; it should set up any locking required by the devlock and devunlock functions, interrupts for the driver and any further lines required to access the chip as approprate. Once this has returned, the chip driver assumes that the platform is fully prepared for it to call the other chip access functions.
Board-level partition initialisation hook. This should set up the
partitionarray of the device struct in a way which is appropriate to the platform. For example, the partitions may be set as fixed ranges of blocks, or by CDL. This is called at the end of the chip initialisation routine and may, for example, call into the chip to read out a "partition table" if one is present on the board. If you do not set up partitions, applications will not be able to use the high-level chip access functions provided the NAND library.
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