Commit Graph

37 Commits

Author SHA1 Message Date
Wolfram Sang
e51d565ff6 spi: Move at25 (for SPI eeproms) to /drivers/misc/eeprom
Signed-off-by: Wolfram Sang <w.sang@pengutronix.de>
Signed-off-by: Jean Delvare <khali@linux-fr.org>
2009-01-26 21:19:54 +01:00
David Brownell
d29389de0b spi_gpio driver
Generalize the old at91rm9200 "bootstrap" bitbanging SPI master driver as
"spi_gpio", so it works with arbitrary GPIOs and can be configured through
platform_data.  Such SPI masters support:

 - any number of bus instances (bus_num is the platform_device.id)
 - any number of chipselects (one GPIO per spi_device)
 - all four SPI_MODE values, and SPI_CS_HIGH
 - i/o word sizes from 1 to 32 bits;
 - devices configured as with any other spi_master controller

When configured using platform_data, this provides relatively low clock
rates.  On platforms that support inlined GPIO calls, significantly
improved transfer speeds are also possible with a semi-custom driver.
(It's still painful when accessing flash memory, but less so.)

Sanity checked by using this version to replace both native controllers on
a board with six different SPI slaves, relying on three different
SPI_MODE_* values and both SPI_CS_HIGH settings for correct operation.

[akpm@linux-foundation.org: cleanups]
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Acked-by: Magnus Damm <damm@igel.co.jp>
Tested-by: Magnus Damm <damm@igel.co.jp>
Cc: Torgil Svensson <torgil.svensson@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-01-06 15:59:19 -08:00
Shadi Ammouri
60cadec9da spi: new orion_spi driver
This adds an SPI driver for the SPI controller found in various Marvell
Orion ARM SoCs.  It currently supports only one slave, which must use SPI
mode 0.

[dbrownell@users.sourceforge.net: cleanups, meet specs, pass "sparse"]
Signed-off-by: Shadi Ammouri <shadi@marvell.com>
Signed-off-by: Saeed Bishara <saeed@marvell.com>
Signed-off-by: Lennert Buytenhek <buytenh@marvell.com>
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-08-05 14:33:46 -07:00
Robert P. J. Day
6291fe2abc SPI Kconfig simplifications
Use "if SPI_MASTER" to remove numerous dependencies.

[dbrownell@users.sourceforge.net: remove a couple now-needless EXPERIMENTAL dependencies too]
Signed-off-by: Robert P. J. Day <rpjday@crashcourse.ca>
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 10:47:30 -07:00
Joakim Tjernlund
c9bfcb3151 spi_mpc83xx: much improved driver
The current driver may cause glitches on SPI CLK line since one must disable
the SPI controller before changing any HW settings.  Fix this by implementing
a local spi_transfer function that won't change speed and/or word size while
CS is active.

While doing that heavy lifting a few other issues were addressed too:
 - Make word size 16 and 32 work too.
 - Honor bits_per_word and speed_hz in spi transaction.
 - Optimize the common path.

This also stops using the "bitbang" framework (except for a few constants).

[Roel Kluin <12o3l@tiscali.nl>: "irq" needs to be signed]
Signed-off-by: Joakim Tjernlund <Joakim.Tjernlund@transmode.se>
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-05-13 08:02:25 -07:00
Alessandro Guido
79d8c7a8c8 spi: use menuconfig for CONFIG_SPI
Signed-off-by: Alessandro Guido <alessandro.guido@gmail.com>
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-04-28 08:58:31 -07:00
Girish
ccc7baed18 spi: omap2_mcspi handles omap3 too
This adds driver OMAP SPI specific changes to support OMAP 3430

Signed-off-by: Girish S G <girishsg@ti.com>
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-02-06 10:41:11 -08:00
Magnus Damm
37e4664087 spi: SuperH SPI using SCI
Add support for SPI over SCI pins.  SCI is a very simple serial controller
block that can be found on older SuperH processors.  In theory it is
possible to use the SCI hardware block in syncronous mode, but this version
of the driver simply hooks up the bit banging code on the SCI pins.

Signed-off-by: Magnus Damm <damm@igel.co.jp>
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Cc: Paul Mundt <lethal@linux-sh.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-02-06 10:41:11 -08:00
eric miao
2f1a74e5a2 [ARM] pxa: make pxa2xx_spi driver use ssp_request()/ssp_free()
1. make pxa2xx_spi.c use ssp_request() and ssp_free() to get the common
   information of the designated SSP port.

2. remove those IRQ/memory request code, ssp_request() has done that for
   the driver

3. the SPI platform device is thus made psuedo, no resource (memory/IRQ)
   has to be defined, all will be retreived by ssp_request()

4. introduce ssp_get_clk_div() to handle controller difference in clock
   divisor setting

5. use clk_xxx() API for clock enable/disable, and clk_get_rate() to
   handle the different SSP clock frequency between different processors

Signed-off-by: eric miao <eric.miao@marvell.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2008-01-26 15:07:52 +00:00
Mike Frysinger
529a73fbae Blackfin arch: punt CONFIG_BFIN -- we already have CONFIG_BLACKFIN
Signed-off-by: Mike Frysinger <michael.frysinger@analog.com>
Signed-off-by: Bryan Wu <bryan.wu@analog.com>
2007-11-23 14:28:44 +08:00
Anton Vorontsov
328329a7bd spi_mpc83xx handles other processors with QUICC engine
Currently, all QE SPI controllers are almost the same comparing to
MPC83xx's, thus let's use that driver for them.

Tested to work on MPC85xx in loopback mode.

Signed-off-by: Anton Vorontsov <avorontsov@ru.mvista.com>
Acked-by: Kumar Gala <galak@kernel.crashing.org>
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-16 09:43:10 -07:00
Atsushi Nemoto
f2cac67dd3 spi_txx9 controller driver
This is a driver for SPI controller built into TXx9 MIPS SoCs.
This driver is derived from arch/mips/tx4938/toshiba_rbtx4938/spi_txx9.c.

Signed-off-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-07-17 10:23:05 -07:00
Samuel Ortiz
ccdc7bf925 SPI: omap2_mcspi driver
Add OMAP24XX McSPI (Multichannel SPI) controller driver.  This driver is
tested very well under OMAP GIT tree with N800 - Nokia Internet Tablet, and
some other OMAP2 boards.

Recent updates included bugfixes, cleanups, speedups, and better
conformance to the current SPI programming interface.  This doesn't yet
understand the third controller instance on the OMAP 2430.

[david-b@pacbell.net: more minor cleanups to the omap2_mcspi driver]
Signed-off-by: Juha Yrjölä <juha.yrjola@solidboot.com>
Signed-off-by: Trilok Soni <soni.trilok@gmail.com>
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Cc: Tony Lindgren <tony@atomide.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-07-17 10:23:05 -07:00
Andrei Konovalov
ae918c02d3 SPI master driver for Xilinx virtex
Simple SPI master driver for Xilinx SPI controller.
No support for multiple masters.
Not using level 1 drivers from EDK.

[akpm@linux-foundation.org: uninlining]
Signed-off-by: Yuri Frolov <yfrolov@ru.mvista.com>
Signed-off-by: Andrei Konovalov <akonovalov@ru.mvista.com>
Cc: Kumar Gala <galak@gate.crashing.org>
Cc: David Brownell <david-b@pacbell.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-07-17 10:23:05 -07:00
Ben Dooks
447aef1a19 SPI: tle620x power switch driver
Add support for the Infineon TLE62x0 series of low-side driver chips, such
as the TLE6220 or TLE6230.  These can be viewed as output GPIOs specialized
for power switching applications.  The driver provides a userspace
interface to those GPIOs, and to the switch status they provide.

Signed-off-by: Ben Dooks <ben-linux@fluff.org>
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-07-17 10:23:05 -07:00
David Brownell
da0abc275f S3c24xx SPI controllers both select 'bitbang'
Tweak Kconfig for the S3C24XX SPI controller drivers.  Both use the bitbang
framework; only one previously said that.  Plus in this case "select" is
the right way to manage that dependency, since folk will not know up front
to enable bitbang in order to even see those S3C drivers in order to enable
them.

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-07-17 10:23:05 -07:00
Kaiwan N Billimoria
78961a5740 spi_lm70llp parport adapter driver
This adds a driver for the LM70-LLP parport adapter, which is an eval board
for the LM70 temperature sensor.  For those without that board, it may be a
simpler example of a parport-to-SPI adapter then spi_butterfly.

Signed-off-by: Kaiwan N Billimoria <kaiwan@designergraphix.com>

Doc, coding style, and interface updates; build fixes.  Minor rename.

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-07-17 10:23:04 -07:00
Dragos Carp
00b8fd2367 MPC52xx PSC SPI master driver
SPI master driver for MPC52xx using its Programmable Serial Controller.

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Dragos Carp <dragos.carp@toptica.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-05-11 08:29:35 -07:00
Martin Schwidefsky
e25df1205f [S390] Kconfig: menus with depends on HAS_IOMEM.
Add "depends on HAS_IOMEM" to a number of menus to make them
disappear for s390 which does not have I/O memory.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2007-05-10 15:46:07 +02:00
Jan Nikitenko
63bd23591e au1550 SPI controller driver
Here is a driver for the Alchemy au1550 PSC (Programmable Serial
Controller) in SPI master mode.

It supports dma transfers using the Alchemy descriptor based dma controller
for 4-8 bits per word SPI transfers.  For 9-24 bits per word transfers, pio
irq based mode is used to avoid setup of dma channels from scratch on each
number of bits per word change.

Tested with au1550; this may also work on other MIPS Alchemy cpus, like
au1200/au1210/au1250.  Used extensively with SD card connected via SPI;
this handles 8.1MHz SPI clock transfers using dma without any problem (the
highest SPI clock freq possible with au1550 running on 324MHz).

The driver supports sharing of SPI bus by multiple devices.  All features
of Alchemy SPI mode are supported (all SPI modes, msb/lsb first, bits per
word in 4-24 range).

As the SPI clock of the controller depends on main input clock that shall
be configured externally, platform data structure for au1550 SPI controller
driver contains mainclk_hz attribute to define the input clock rate.  From
this value, dividers of the controller for SPI clock are set up for
required frequency.

Signed-off-by: Jan Nikitenko <jan.nikitenko@gmail.com>

Whitespace and section fixups.  Remove partial workaround for platform
setup bug in dma_mask setup; it couldn't work with multiple controllers.

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-05-08 11:15:16 -07:00
Andrea Paterniani
814a8d50eb /dev/spidevB.C interface
Add a filesystem API for <linux/spi/spi.h> stack.  The initial version of
this interface is purely synchronous.

dbrownell@users.sourceforge.net:

 Cleaned up, bugfixed; much simplified; added preliminary documentation.

 Works with mdev given CONFIG_SYSFS_DEPRECATED; and presumably udev.

 Updated SPI_IOC_MESSAGE ioctl to full spi_message semantics, supporting
 groups of one or more transfers (each of which may be full duplex if
 desired).

 This is marked as EXPERIMENTAL with an explicit disclaimer that the API
 (notably the ioctls) is subject to change.

Signed-off-by: Andrea Paterniani <a.paterniani@swapp-eng.it>
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Cc: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-05-08 11:15:15 -07:00
Wu, Bryan
a5f6abd4f7 Blackfin: blackfin on-chip SPI controller driver
This patch implements the driver necessary use the Analog Devices Blackfin
processor's SPI Port.

Signed-off-by: Bryan Wu <bryan.wu@analog.com>
Cc: David Brownell <david-b@pacbell.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-05-07 12:12:58 -07:00
Haavard Skinnemoen
754ce4f299 [PATCH] SPI: atmel_spi driver
Driver for the Atmel on-chip SPI master controller.

Tested primarily on AVR32/AT32AP7000/ATSTK1000 using mtd_dataflash and the
jffs2 filesystem.  Should also work fine on various AT91 ARM-based chips
like AT91SAM926x and AT91RM9200.

Hardware documentation can be found in the AT32AP7000 data sheet, or its
AT91 siblings, which can be downloaded from

http://www.atmel.com/dyn/products/datasheets.asp?family_id=682

Signed-off-by: Haavard Skinnemoen <hskinnemoen@atmel.com>
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-02-14 08:09:53 -08:00
David Brownell
b587b13a4f [PATCH] SPI eeprom driver
This is adds a simple SPI EEPROM driver, providing access to the EEPROM
through sysfs much like the I2C "eeprom" driver ...  except this driver
supports write access, and multiple EEPROM sizes.

From: "Tuppa, Walter" <walter.tuppa@siemens.com>

Since I have EEPROMs on SPI with different address sizing, I made some
changes to your at25.c to support them.  Works perfectly.  (Also includes a
small bugfix for the "what size address" test.)

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Walter Tuppa <walter.tuppa@siemens.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-02-12 09:48:31 -08:00
Andrea Paterniani
69c202afa8 [PATCH] SPI: Freescale iMX SPI controller driver (BIS+)
Add the SPI controller driver for Freescale i.MX(S/L/1).
Main features summary:

 > Per chip setup via board specific code and/or protocol driver.
 > Per transfer setup.
 > PIO transfers.
 > DMA transfers.
 > Managing of NULL tx / rx buffer for rd only / wr only transfers.

This patch replace patch-2.6.20-rc4-spi_imx with the following changes:
 > Few cosmetic changes.
 > Function map_dma_buffers now return 0 for success and -1 for failure.
 > Solved a bug inside spi_imx_probe function (wrong error path).
 > Solved a bug inside setup function (bad undo setup for max_speed_hz).
 > For read-only transfers, always write zero bytes.

This is almost the same as the 'BIS' version sent by Andrea, except for
updating the 'DUMMY' byte so that read-only transfers shift out zeroes.
That part of the API changed recently, since some half duplex peripheral
chips require that semantic.

Signed-off-by: Andrea Paterniani <a.paterniani@swapp-eng.it>
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-02-12 09:48:30 -08:00
David Brownell
fdb3c18d63 [PATCH] SPI controller driver for OMAP Microwire
This adds a SPI driver for the Microwire controller on OMAP1 chips.  This
driver has been used in the Linux-OMAP tree for some time now, including
with some of those displays using standardized 9-bit commands followed by
data with 8-bit words.

Microwire only supports half duplex transfers, but that's all that most SPI
protocols need.  When full duplex, or higher speeds, are needed there are
several other controllers that can be used on OMAP.

[akpm@osdl.org: cleanups]
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Imre Deak <imre.deak@solidboot.com>
Signed-off-by: Juha Yrjola <juha.yrjola@solidboot.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-02-12 09:48:30 -08:00
David Brownell
85abfaa782 [PATCH] SPI Kconfig fix
Minor Kconfig cleanup ... put the SPI_S3C24XX entry in the
correct location (alphabetical order).

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-02-12 09:48:30 -08:00
Matt LaPlante
3cb2fccc5f Fix misc Kconfig typos
Fix various Kconfig typos.

Signed-off-by: Matt LaPlante <kernel1@cyberdogtech.com>
Acked-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Adrian Bunk <bunk@stusta.de>
2006-11-30 05:22:59 +01:00
Ben Dooks
7fba53402e [PATCH] S3C24XX: hardware SPI driver
Hardware based SPI driver for Samsung S3C24XX SoC systems

Signed-off-by: Ben Dooks <ben-linux@fluff.org>
Cc: David Brownell <david-b@pacbell.net>
Cc: Greg KH <greg@kroah.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-05-21 12:59:19 -07:00
Ben Dooks
1fc7547d4b [PATCH] S3C24XX: GPIO based SPI driver
SPI driver for SPI by GPIO on the Samsung S3C24XX series of SoC processors.

Signed-off-by: Ben Dooks <ben-linux@fluff.org>
Cc: Greg KH <greg@kroah.com>
Cc: David Brownell <david-b@pacbell.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-05-21 12:59:19 -07:00
Kumar Gala
ccf06998fe [PATCH] spi: add spi master driver for Freescale MPC83xx SPI controller
This driver supports the SPI controller on the MPC83xx SoC devices from
Freescale.  Note, this driver supports only the simple shift register SPI
controller and not the descriptor based CPM or QUICCEngine SPI controller.

Signed-off-by: Kumar Gala <galak@kernel.crashing.org>
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Cc: Greg KH <greg@kroah.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-05-21 12:59:19 -07:00
Stephen Street
e0c9905e87 [PATCH] SPI: add PXA2xx SSP SPI Driver
This driver turns a PXA2xx synchronous serial port (SSP) into a SPI master
controller (see Documentation/spi/spi_summary).  The driver has the following
features:

- Support for any PXA2xx SSP
- SSP PIO and SSP DMA data transfers.
- External and Internal (SSPFRM) chip selects.
- Per slave device (chip) configuration.
- Full suspend, freeze, resume support.

Signed-off-by: Stephen Street <stephen@streetfiresound.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Cc: David Brownell <david-b@pacbell.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2006-05-16 14:33:56 -07:00
David Brownell
9c1da3cb46 [PATCH] SPI: spi_butterfly, restore lost deltas
This resolves some minor version skew glitches that accumulated for the AVR
Butterfly adapter driver, which caused among other things the existence of
a duplicate Kconfig entry.  Most of it boils down to comment updates, but in
one case it removes some now-superfluous code that would be better if not
copied into other controller-level drivers.

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
2006-02-06 12:17:17 -08:00
David Brownell
2e10c84b9c [PATCH] SPI: add spi_butterfly driver
This adds a bitbanging parport based adaptor cable for AVR Butterfly, giving
SPI links to its DataFlash chip and (eventually) firmware running in the card.

Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2006-01-13 16:29:56 -08:00
David Brownell
7111763d39 [PATCH] spi: misc fixes
This collects some small SPI patches that seem to be missing from the MM tree:

  - spi_butterfly kbuild hooks got dropped somehow; this restores them
  - quick fix for a (theoretical?) m25p80_write() oops noted by Andrew
  - quick fix for a potential config-specific oops for mtd_dataflash()
  - minor doc tweaks

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>
2006-01-13 16:29:56 -08:00
David Brownell
9904f22a72 [PATCH] spi: add spi_bitbang driver
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>
2006-01-13 16:29:55 -08:00
David Brownell
8ae12a0d85 [PATCH] spi: simple SPI framework
This is the core of a small SPI framework, implementing the model of a
queue of messages which complete asynchronously (with thin synchronous
wrappers on top).

  - It's still less than 2KB of ".text" (ARM).  If there's got to be a
    mid-layer for something so simple, that's the right size budget.  :)

  - The guts use board-specific SPI device tables to build the driver
    model tree.  (Hardware probing is rarely an option.)

  - This version of Kconfig includes no drivers.  At this writing there
    are two known master controller drivers (PXA/SSP, OMAP MicroWire)
    and three protocol drivers (CS8415a, ADS7846, DataFlash) with LKML
    mentions of other drivers in development.

  - No userspace API.  There are several implementations to compare.
    Implement them like any other driver, and bind them with sysfs.

The changes from last version posted to LKML (on 11-Nov-2005) are minor,
and include:

  - One bugfix (removes a FIXME), with the visible effect of making device
    names be "spiB.C" where B is the bus number and C is the chipselect.

  - The "caller provides DMA mappings" mechanism now has kerneldoc, for
    DMA drivers that want to be fancy.

  - Hey, the framework init can be subsys_init.  Even though board init
    logic fires earlier, at arch_init ... since the framework init is
    for driver support, and the board init support uses static init.

  - Various additional spec/doc clarifications based on discussions
    with other folk.  It adds a brief "thank you" at the end, for folk
    who've helped nudge this framework into existence.

As I've said before, I think that "protocol tweaking" is the main support
that this driver framework will need to evolve.

From: Mark Underwood <basicmark@yahoo.com>

  Update the SPI framework to remove a potential priority inversion case by
  reverting to kmalloc if the pre-allocated DMA-safe buffer isn't available.

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>
2006-01-13 16:29:54 -08:00