9904f22a72
This adds a bitbanging spi master, hooking up to board/adapter-specific glue code which knows how to set and read the signals (gpios etc). This code kicks in after the glue code creates a platform_device with the right platform_data. That data includes I/O loops, which will usually come from expanding an inline function (provided in the header). One goal is that the I/O loops should be easily optimized down to a few GPIO register accesses, in common cases, for speed and minimized overhead. This understands all the currently defined protocol tweaking options in the SPI framework, and might eventually serve as as reference implementation. - different word sizes (1..32 bits) - differing clock rates - SPI modes differing by CPOL (affecting chip select and I/O loops) - SPI modes differing by CPHA (affecting I/O loops) - delays (usecs) after transfers - temporarily deselecting chips in mid-transfer A lot of hardware could work with this framework, though common types of controller can't reach peak performance without switching to a driver structure that supports pipelining of transfers (e.g. DMA queues) and maybe controllers (e.g. IRQ driven). Signed-off-by: David Brownell <dbrownell@users.sourceforge.net> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
90 lines
2.8 KiB
Plaintext
90 lines
2.8 KiB
Plaintext
#
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# SPI driver configuration
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#
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# NOTE: the reason this doesn't show SPI slave support is mostly that
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# nobody's needed a slave side API yet. The master-role API is not
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# fully appropriate there, so it'd need some thought to do well.
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#
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menu "SPI support"
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config SPI
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bool "SPI support"
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help
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The "Serial Peripheral Interface" is a low level synchronous
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protocol. Chips that support SPI can have data transfer rates
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up to several tens of Mbit/sec. Chips are addressed with a
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controller and a chipselect. Most SPI slaves don't support
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dynamic device discovery; some are even write-only or read-only.
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SPI is widely used by microcontollers to talk with sensors,
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eeprom and flash memory, codecs and various other controller
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chips, analog to digital (and d-to-a) converters, and more.
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MMC and SD cards can be accessed using SPI protocol; and for
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DataFlash cards used in MMC sockets, SPI must always be used.
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SPI is one of a family of similar protocols using a four wire
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interface (select, clock, data in, data out) including Microwire
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(half duplex), SSP, SSI, and PSP. This driver framework should
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work with most such devices and controllers.
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config SPI_DEBUG
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boolean "Debug support for SPI drivers"
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depends on SPI && DEBUG_KERNEL
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help
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Say "yes" to enable debug messaging (like dev_dbg and pr_debug),
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sysfs, and debugfs support in SPI controller and protocol drivers.
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#
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# MASTER side ... talking to discrete SPI slave chips including microcontrollers
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#
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config SPI_MASTER
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# boolean "SPI Master Support"
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boolean
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default SPI
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help
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If your system has an master-capable SPI controller (which
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provides the clock and chipselect), you can enable that
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controller and the protocol drivers for the SPI slave chips
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that are connected.
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comment "SPI Master Controller Drivers"
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depends on SPI_MASTER
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config SPI_BITBANG
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tristate "Bitbanging SPI master"
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depends on SPI_MASTER && EXPERIMENTAL
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help
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With a few GPIO pins, your system can bitbang the SPI protocol.
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Select this to get SPI support through I/O pins (GPIO, parallel
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port, etc). Or, some systems' SPI master controller drivers use
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this code to manage the per-word or per-transfer accesses to the
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hardware shift registers.
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This is library code, and is automatically selected by drivers that
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need it. You only need to select this explicitly to support driver
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modules that aren't part of this kernel tree.
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#
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# Add new SPI master controllers in alphabetical order above this line
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#
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#
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# There are lots of SPI device types, with sensors and memory
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# being probably the most widely used ones.
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#
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comment "SPI Protocol Masters"
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depends on SPI_MASTER
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#
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# Add new SPI protocol masters in alphabetical order above this line
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#
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# (slave support would go here)
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endmenu # "SPI support"
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