Linux kernel source tree
5af42209a4
The sama7g5 QSPI controller uses dedicated clocks for the QSPI Controller Interface and the QSPI Controller Core, and requires synchronization before accessing registers or bit fields. QSPI_SR.SYNCBSY must be zero before accessing any of the bits: QSPI_CR.QSPIEN, QSPI_CR.QSPIDIS, QSPI_CR.SRFRSH, QSPI_CR.SWRST, QSPI_CR.UPDCFG, QSPI_CR.STTFR, QSPI_CR.RTOUT, QSPI_CR.LASTXFER. Also, the QSPI controller core configuration can be updated by writing the QSPI_CR.UPDCFG bit to ‘1’. This is needed by the following registers: QSPI_MR, QSPI_SCR, QSPI_IAR, QSPI_WICR, QSPI_IFR, QSPI_RICR, QSPI_SMR, QSPI_SKR,QSPI_REFRESH, QSPI_WRACNT QSPI_PCALCFG. The Octal SPI supports frequencies up to 200 MHZ DDR. The need for output impedance calibration arises. To avoid the degradation of the signal quality, a PAD calibration cell is used to adjust the output impedance to the driven I/Os. The transmission flow requires different sequences for setting the configuration and for the actual transfer, than what is in the sama5d2 and sam9x60 versions of the IP. Different interrupts are handled. aq->ops->set_cfg() and aq->ops->transfer() are introduced to help differentiating the flows. Tested single and octal SPI mode with mx66lm1g45g. Signed-off-by: Tudor Ambarus <tudor.ambarus@microchip.com> Link: https://lore.kernel.org/r/20211214133404.121739-1-tudor.ambarus@microchip.com [varshini.rajendran@microchip.com: Fixed conflicts and ported to 6.1.4] Signed-off-by: Varshini Rajendran <varshini.rajendran@microchip.com> [ csokas.bence: Forward-port to master and address feedback ] Signed-off-by: Csókás, Bence <csokas.bence@prolan.hu> Link: https://patch.msgid.link/20241128174316.3209354-3-csokas.bence@prolan.hu Signed-off-by: Mark Brown <broonie@kernel.org> |
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Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the reStructuredText markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.