This patch fixes the setup_transfer logic to account for the case where
multiple messages to different SPI devices are in the queue simultaneously.
With the current logic, the second message in the queue will end up
using the transfer parameters for the previous message in the queue.
The fix is to reinitialize the transfer parameters for each message
rather than only once on the first message.
Signed-off-by: Brian Niebuhr <bniebuhr@efjohnson.com>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
There are some boards that do not strictly follow SPI standard and use
only 3 wires (SCLK, MOSI or MISO, SS) for connecting some simple auxiliary
chips and controls them with GPIO based 'spi controller'. In this
configuration the MISO or MOSI line is missing (it is not required if the
chip does not transfer any data back to host or host only reads data from
chip).
This patch adds support for such non-standard configuration in GPIO-based
SPI controller. It has been tested in configuration without MISO pin.
Reviewed-by: Kyungmin Park <kyungmin.park@samsung.com>
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Acked-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
This patch adds a new flags argument to bitbang_txrx_be_cpha0 and
bitbang_txrx_be_cpha1 transfer functions. This enables support for
SPI_MASTER_NO_{TX,RX} transfer modes. The change should have no impact
on speed of the existing drivers. bitbank_txrx_* functions are usually
inlined into the drivers. When the argument is equal to constant zero,
the optimizer would be able to eliminate the dead code (flags checks)
easily. Tested on ARM and GCC 4.4.x and in all cases the checks were
eliminated in the inlined function.
Reviewed-by: Kyungmin Park <kyungmin.park@samsung.com>
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Acked-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
This change fixes 8-bit transfers and RX-only transfers. The
SPI100k framework requires minimum 16-bit words to be written, so 8-bit
transfers must be shited by 8 bits and sent out as a 16-bit word.
Additionally, receive-only transfers were failing due to the
perceived need to fill the TX buffer with something. This is in
fact not needed.
Signed-off-by: Cory Maccarrone <darkstar6262@gmail.com>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
SPI bus locking API to allow exclusive access to the SPI bus, especially, but
not limited to, for the mmc_spi driver.
Coded according to an outline from Grant Likely; here is his
specification (accidentally swapped function names corrected):
It requires 3 things to be added to struct spi_master.
- 1 Mutex
- 1 spin lock
- 1 flag.
The mutex protects spi_sync, and provides sleeping "for free"
The spinlock protects the atomic spi_async call.
The flag is set when the lock is obtained, and checked while holding
the spinlock in spi_async(). If the flag is checked, then spi_async()
must fail immediately.
The current runtime API looks like this:
spi_async(struct spi_device*, struct spi_message*);
spi_sync(struct spi_device*, struct spi_message*);
The API needs to be extended to this:
spi_async(struct spi_device*, struct spi_message*)
spi_sync(struct spi_device*, struct spi_message*)
spi_bus_lock(struct spi_master*) /* although struct spi_device* might
be easier */
spi_bus_unlock(struct spi_master*)
spi_async_locked(struct spi_device*, struct spi_message*)
spi_sync_locked(struct spi_device*, struct spi_message*)
Drivers can only call the last two if they already hold the spi_master_lock().
spi_bus_lock() obtains the mutex, obtains the spin lock, sets the
flag, and releases the spin lock before returning. It doesn't even
need to sleep while waiting for "in-flight" spi_transactions to
complete because its purpose is to guarantee no additional
transactions are added. It does not guarantee that the bus is idle.
spi_bus_unlock() clears the flag and releases the mutex, which will
wake up any waiters.
The difference between spi_async() and spi_async_locked() is that the
locked version bypasses the check of the lock flag. Both versions
need to obtain the spinlock.
The difference between spi_sync() and spi_sync_locked() is that
spi_sync() must hold the mutex while enqueuing a new transfer.
spi_sync_locked() doesn't because the mutex is already held. Note
however that spi_sync must *not* continue to hold the mutex while
waiting for the transfer to complete, otherwise only one transfer
could be queued up at a time!
Almost no code needs to be written. The current spi_async() and
spi_sync() can probably be renamed to __spi_async() and __spi_sync()
so that spi_async(), spi_sync(), spi_async_locked() and
spi_sync_locked() can just become wrappers around the common code.
spi_sync() is protected by a mutex because it can sleep
spi_async() needs to be protected with a flag and a spinlock because
it can be called atomically and must not sleep
Signed-off-by: Ernst Schwab <eschwab@online.de>
[grant.likely@secretlab.ca: use spin_lock_irqsave()]
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
Tested-by: Matt Fleming <matt@console-pimps.org>
Tested-by: Antonio Ospite <ospite@studenti.unina.it>
Fixes build errors caused by the:
- OF device_node pointer being moved into struct device
- removal of the match_table field from struct of_platform_driver
Signed-off-by: Anatolij Gustschin <agust@denx.de>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
This patch fixes a build error caused by the OF device_node pointer
being moved into struct device.
Fixes bug introduced by commit 61c7a080a5
(of: Always use 'struct device.of_node' to get device node pointer)
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
CC: Sean MacLennan <smaclennan@pikatech.com>
CC: spi-devel-general@lists.sourceforge.net
CC: devicetree-discuss@lists.ozlabs.org
Commit 58f9b0b024, "of: eliminate
of_device->node and dev_archdata->{of,prom}_node" changed the location
of the device_node pointer. Most drivers were converted to the new
location, but the xilinx_spi_of driver was missed and now fails to
compile.
This patch fixes up the xilinx_spi_of driver to use the new location.
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
Computation of the clock prescaler value returned bogus results if
the requested SPI clock was impossible to set. It now sets either
the maximum or minimum clock frequency, as appropriate.
Signed-off-by: Thomas Koeller <thomas.koeller@baslerweb.com>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
A number of files in drivers/spi fail checkincludes.pl due to the double
include of <linux/spi/spi_bitbang.h>.
The first include is needed to get the struct spi_bitbang definition and
the spi_bitbang_* function prototypes.
The second include happens after defining EXPAND_BITBANG_TXRX to get the
inlined bitbang_txrx_* utility functions.
The <linux/spi/spi_bitbang.h> header is also included by a number of other
spi drivers, as well as some arch/ code, in order to use struct spi_bitbang
and the associated functions.
To fix the double include, and remove any potential confusion about it, move
the inlined bitbang_txrx_* functions to a new private header in drivers/spi
and also remove the need to define EXPAND_BITBANG_TXRX.
Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
This patch adds an SPI master driver for the Cirrus EP93xx SPI controller found
in EP93xx chips.
Signed-off-by: Mika Westerberg <mika.westerberg@iki.fi>
Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Acked-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
Turbo mode allows to read data to shift register when rx-buffer
is full thus improving the perfomance. This feature is available
for RX-only mode.
In PIO turbo mode when the penultimate word is available
in RX-buffer the controller should be disabled before reading data
to prevent the next transaction triggering. The controller itself
handles the last word to be correctly loaded to shift-register and
then transferred to RX-buffer.
The turbo mode is enabled by setting turbo_mode parameter to 1.
This parameter is a part of omap2_mcspi_device_config structure
which is passed through the spi_device controller_data pointer.
Signed-off-by: Roman Tereshonkov <roman.tereshonkov@nokia.com>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
The value 160 has been obtained as optimal in testing it for
wl1271 which use spi for communication.
In some sense this change might also influence on other spi devices
connected to omap2_mcspi controller.
Signed-off-by: Roman Tereshonkov <roman.tereshonkov@nokia.com>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
This fix prevents queue being marked as "stopped", if data exists
in the queue list.
Signed-off-by: Grzegorz Sygieda <grzegorz.sygieda@tieto.com>
Signed-off-by: Lukasz Baj <lukasz.baj@tieto.com>
Signed-off-by: Linus Walleij <linus.walleij@stericsson.com>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
This adds support for a further ST variant of the PL022 called
PL023. Some differences in the control registers due to being
stripped down to SPI mode only, and a new clock feedback sample
delay config setting is available.
Signed-off-by: Linus Walleij <linus.walleij@stericsson.com>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
The PL022 SPI driver did not cleanly separate between the
original unmodified ARM version and the ST Microelectronics
versions. Split this more cleanly and fix some whitespace
moaning from checkpatch at the same time.
Signed-off-by: Linus Walleij <linus.walleij@stericsson.com>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
This fixes a typo were map_tx_dma is used instead of
map_rx_dma, casing the driver to unmap rx_dma when it
shouldn't.
Signed-off-by: Joakim Tjernlund <Joakim.Tjernlund@transmode.se>
Acked-by: Anton Vorontsov <cbouatmailru@gmail.com>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
QE mode uses Little Endian so words > 8 bits are byte swapped.
Workaround this by always enforcing wordsize 8 for words
> 8 bits. Unfortunately this will not work for LSB transfers
where wordsize is > 8 bits so disable these for now.
Also move the different quirks into its own function to keep
mpc8xxx_spi_setup_transfer() sane.
Signed-off-by: Joakim Tjernlund <Joakim.Tjernlund@transmode.se>
Acked-by: Anton Vorontsov <cbouatmailru@gmail.com>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
tx_dma/rx_dma are already set to a dummy buffer when no
tx/rx buffer and t->tx_dma/t->rx_dma does not contain a dma
address, but NULL.
This may lead to corruption of kernel memory. Fix this by
leaving tx_dma/rx_dma alone.
Do not INIT_TX_RX while controller is enabled, this is bad according
to the MPC8321 manual.
Signed-off-by: Joakim Tjernlund <Joakim.Tjernlund@transmode.se>
Acked-by: Anton Vorontsov <cbouatmailru@gmail.com>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
Merging in current state of Linus' tree to deal with merge conflicts and
build failures in vio.c after merge.
Conflicts:
drivers/i2c/busses/i2c-cpm.c
drivers/i2c/busses/i2c-mpc.c
drivers/net/gianfar.c
Also fixed up one line in arch/powerpc/kernel/vio.c to use the
correct node pointer.
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
.name, .match_table and .owner are duplicated in both of_platform_driver
and device_driver. This patch is a removes the extra copies from struct
of_platform_driver and converts all users to the device_driver members.
This patch is a pretty mechanical change. The usage model doesn't change
and if any drivers have been missed, or if anything has been fixed up
incorrectly, then it will fail with a compile time error, and the fixup
will be trivial. This patch looks big and scary because it touches so
many files, but it should be pretty safe.
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
Acked-by: Sean MacLennan <smaclennan@pikatech.com>
* 'omap-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tmlind/linux-omap-2.6: (113 commits)
omap4: Add support for i2c init
omap: Fix i2c platform init code for omap4
OMAP2 clock: fix recursive spinlock attempt when CONFIG_CPU_FREQ=y
OMAP powerdomain, hwmod, omap_device: add some credits
OMAP4 powerdomain: Support LOWPOWERSTATECHANGE for powerdomains
OMAP3 clock: add support for setting the divider for sys_clkout2 using clk_set_rate
OMAP4 powerdomain: Fix pwrsts flags for ALWAYS ON domains
OMAP: timers: Fix clock source names for OMAP4
OMAP4 clock: Support clk_set_parent
OMAP4: PRCM: Add offset defines for all CM registers
OMAP4: PRCM: Add offset defines for all PRM registers
OMAP4: PRCM: Remove duplicate definition of base addresses
OMAP4: PRM: Remove MPU internal code name and apply PRCM naming convention
OMAP4: CM: Remove non-functional registers in ES1.0
OMAP: hwmod: Replace WARN by pr_warning for clockdomain check
OMAP: hwmod: Rename hwmod name for the MPU
OMAP: hwmod: Do not exit the iteration if one clock init failed
OMAP: hwmod: Replace WARN by pr_warning if clock lookup failed
OMAP: hwmod: Remove IS_ERR check with omap_clk_get_by_name return value
OMAP: hwmod: Fix wrong pointer iteration in oh->slaves
...
Change dependency to ARCH_OMAP2PLUS to allow systems based on
omap24xx, omap34xx or omap44xx
Cc: spi-devel-general@lists.sourceforge.net
Signed-off-by: Syed Rafiuddin <rafiuddin.syed@ti.com>
Signed-off-by: Abraham Arce <x0066660@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial: (44 commits)
vlynq: make whole Kconfig-menu dependant on architecture
add descriptive comment for TIF_MEMDIE task flag declaration.
EEPROM: max6875: Header file cleanup
EEPROM: 93cx6: Header file cleanup
EEPROM: Header file cleanup
agp: use NULL instead of 0 when pointer is needed
rtc-v3020: make bitfield unsigned
PCI: make bitfield unsigned
jbd2: use NULL instead of 0 when pointer is needed
cciss: fix shadows sparse warning
doc: inode uses a mutex instead of a semaphore.
uml: i386: Avoid redefinition of NR_syscalls
fix "seperate" typos in comments
cocbalt_lcdfb: correct sections
doc: Change urls for sparse
Powerpc: wii: Fix typo in comment
i2o: cleanup some exit paths
Documentation/: it's -> its where appropriate
UML: Fix compiler warning due to missing task_struct declaration
UML: add kernel.h include to signal.c
...
The following structure elements duplicate the information in
'struct device.of_node' and so are being eliminated. This patch
makes all readers of these elements use device.of_node instead.
(struct of_device *)->node
(struct dev_archdata *)->prom_node (sparc)
(struct dev_archdata *)->of_node (powerpc & microblaze)
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
In order to prevent code ambiguous, add namespace on functions in ssp driver.
Signed-off-by: Haojian Zhuang <haojian.zhuang@marvell.com>
Acked-by: Liam Girdwood <lrg@slimlogic.co.uk>
Signed-off-by: Eric Miao <eric.y.miao@gmail.com>
Signed-off-by: Haojian Zhuang <haojian.zhuang@marvell.com>
Acked-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: Eric Miao <eric.y.miao@gmail.com>
The previous definitions of SSCR0_SCR and SSCR0_SerClkDiv() prevented
them being used simultaneously when supporting multiple PXA SoCs, esp.
in drivers/spi/pxa2xx_spi.c, make them correct.
The change from SSCR0_SerClkDiv(2) to SSCR0_SCR(2), will make the result
a little bit different in pxa2xx_spi_probe(), however, since that's only
used as a default initialization value, it's acceptable.
Signed-off-by: Eric Miao <eric.y.miao@gmail.com>
Replaces %04x by %08x for 32-bits data output.
Signed-off-by: Roman Tereshonkov <roman.tereshonkov@nokia.com>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
mcspi_write_chconf0 is used to control rx/tx triggering.
Post-write flushing is needed to get the immediate effect.
Signed-off-by: Roman Tereshonkov <roman.tereshonkov@nokia.com>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
The memory for dev variable is allocated as a part of
spi_device structure memory which the dev belongs to.
Thus when the memory is released the right pointer is used.
Signed-off-by: Roman Tereshonkov <roman.tereshonkov@nokia.com>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
In success case the function bus_find_device_by_name calls
get_device. In our context put_device should be called to
decrease the device count usage.
Signed-off-by: Roman Tereshonkov <roman.tereshonkov@nokia.com>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
percpu.h is included by sched.h and module.h and thus ends up being
included when building most .c files. percpu.h includes slab.h which
in turn includes gfp.h making everything defined by the two files
universally available and complicating inclusion dependencies.
percpu.h -> slab.h dependency is about to be removed. Prepare for
this change by updating users of gfp and slab facilities include those
headers directly instead of assuming availability. As this conversion
needs to touch large number of source files, the following script is
used as the basis of conversion.
http://userweb.kernel.org/~tj/misc/slabh-sweep.py
The script does the followings.
* Scan files for gfp and slab usages and update includes such that
only the necessary includes are there. ie. if only gfp is used,
gfp.h, if slab is used, slab.h.
* When the script inserts a new include, it looks at the include
blocks and try to put the new include such that its order conforms
to its surrounding. It's put in the include block which contains
core kernel includes, in the same order that the rest are ordered -
alphabetical, Christmas tree, rev-Xmas-tree or at the end if there
doesn't seem to be any matching order.
* If the script can't find a place to put a new include (mostly
because the file doesn't have fitting include block), it prints out
an error message indicating which .h file needs to be added to the
file.
The conversion was done in the following steps.
1. The initial automatic conversion of all .c files updated slightly
over 4000 files, deleting around 700 includes and adding ~480 gfp.h
and ~3000 slab.h inclusions. The script emitted errors for ~400
files.
2. Each error was manually checked. Some didn't need the inclusion,
some needed manual addition while adding it to implementation .h or
embedding .c file was more appropriate for others. This step added
inclusions to around 150 files.
3. The script was run again and the output was compared to the edits
from #2 to make sure no file was left behind.
4. Several build tests were done and a couple of problems were fixed.
e.g. lib/decompress_*.c used malloc/free() wrappers around slab
APIs requiring slab.h to be added manually.
5. The script was run on all .h files but without automatically
editing them as sprinkling gfp.h and slab.h inclusions around .h
files could easily lead to inclusion dependency hell. Most gfp.h
inclusion directives were ignored as stuff from gfp.h was usually
wildly available and often used in preprocessor macros. Each
slab.h inclusion directive was examined and added manually as
necessary.
6. percpu.h was updated not to include slab.h.
7. Build test were done on the following configurations and failures
were fixed. CONFIG_GCOV_KERNEL was turned off for all tests (as my
distributed build env didn't work with gcov compiles) and a few
more options had to be turned off depending on archs to make things
build (like ipr on powerpc/64 which failed due to missing writeq).
* x86 and x86_64 UP and SMP allmodconfig and a custom test config.
* powerpc and powerpc64 SMP allmodconfig
* sparc and sparc64 SMP allmodconfig
* ia64 SMP allmodconfig
* s390 SMP allmodconfig
* alpha SMP allmodconfig
* um on x86_64 SMP allmodconfig
8. percpu.h modifications were reverted so that it could be applied as
a separate patch and serve as bisection point.
Given the fact that I had only a couple of failures from tests on step
6, I'm fairly confident about the coverage of this conversion patch.
If there is a breakage, it's likely to be something in one of the arch
headers which should be easily discoverable easily on most builds of
the specific arch.
Signed-off-by: Tejun Heo <tj@kernel.org>
Guess-its-ok-by: Christoph Lameter <cl@linux-foundation.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com>
omap2_mcspi_transfer() gets called in omap2_mcspi_work() when the
transaction speed_hz or bits_per_word fields are non-zero.
omap2_mcspi_transfer() does not look at the speed_hz field so
the override speed value is ignored.
The code should probably change to one of these options.
1. Skip the call to omap2_mcsp_transfer() if the only reason was a
non-zero speed_hz and it's not going to be used.
2. Use the new speed_hz value provided
The patch below uses the speed_hz value.
Signed-off-by: Scott Ellis <scott@jumpnowtek.com>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
Check spi->controller_state before dereferencing.
Shows up NULL here when using spi_alloc_device()/spi_add_device()
and spi_add_device() fails before spi_setup(). Calling spi_dev_put()
on the leftover spi_device results in the error.
Signed-off-by: Scott Ellis <scott@jumpnowtek.com>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
DMA can only be done from physical addresses; move the "virt_to_phys"
source/destination buffer address translation from the dbdma queueing
functions (since the hardware can only DMA to/from physical addresses)
to their respective users.
Signed-off-by: Manuel Lauss <manuel.lauss@gmail.com>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Remove dbdma compat macros, move remaining users over to default
queueing functions and -flags.
(Queueing function signature has changed in order to give
a build failure instead of silent functional changes due
to the no longer implicitly specified DDMA_FLAGS_IE flag)
Signed-off-by: Manuel Lauss <manuel.lauss@gmail.com>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
* 'next-spi' of git://git.secretlab.ca/git/linux-2.6: (31 commits)
spi: Correct SPI clock frequency setting in spi_mpc8xxx
spi/spi_s3c64xx.c: Fix continuation line formats
spi/dw_spi: Fix dw_spi_mmio to depend on HAVE_CLK
spi/dw_spi: Allow dw_spi.c to be a module
spi/dw_spi: mmio code style fixups
Memory-mapped dw_spi driver
spi/dw_spi: fix missing export of dw_spi_remove_host
spi/dw_spi: conditional transfer mode changes
spi/dw_spi: remove conditional from 'poll_transfer'.
spi/dw_spi: fixed a spelling typo in a warning message.
spi/dw_spi: add return value to empty mrst_spi_debugfs_init()
spi/dw_spi: enable platform specific chipselect.
spi/dw_spi: add a FIFO depth detection
spi/dw_spi: fix __init/__devinit section mismatch
spi: xilinx_spi: Fix up I/O routine wrapping bogosity.
spi/spi_imx: add device information by switching pr_debug() to dev_dbg()
spi: update MSIOF includes
spi/dw_spi: refine the IRQ mode working flow
spi/dw_spi: add a missed dw_spi_remove_host() in exit sequence
spi/dw_spi: bug fix in wait_till_not_busy()
...
Correct SPI clock frequency division factor rounding, preventing clock rates
higher than the maximum specified clock frequency being used.
When specifying spi-max-frequency = <10000000> in the device tree,
the resulting frequency was 11.1 MHz, with spibrg being 133333332.
According to the freescale data sheet [1], the spi clock rate is
spiclk = spibrg / (4 * (pm+1))
The existing code calculated
pm = mpc8xxx_spi->spibrg / (hz * 4); pm--;
resulting in pm = (int) (3.3333) - 1 = 2,
resulting in spiclk = 133333332/(4*(2+1)) = 11111111
With the fix,
pm = (mpc8xxx_spi->spibrg - 1) / (hz * 4) + 1; pm--;
resulting in pm = (int) (4.3333) - 1 = 3,
resulting in spiclk = 133333332/(4*(3+1)) = 8333333
Without the fix, for every desired SPI frequency that
is not exactly derivable from spibrg, pm will be too
small due to rounding down, resulting in a too high SPI clock,
so we need a pm which is one higher.
For values that are exactly derivable, spibrg will
be dividable by (hz*4) without remainder, and
(int) ((spibrg-1)/(hz*4)) will be one lower than
(int) (spibrg)/(hz*4), which is compensated by adding 1.
For these values, the fixed version calculates the same pm
as the unfixed version.
For all values that are not exactly derivable,
spibrg will be not dividable by (hz*4) without
remainder, and (int) ((spibrg-1)/(hz*4)) will be
the same as (int) (spibrg)/(hz*4), and the calculated pm will
be one higher than calculated by the unfixed version.
References:
[1] http://www.freescale.com/files/32bit/doc/ref_manual/MPC8315ERM.pdf,
page 22-10 -> 1398
Signed-off-by: Ernst Schwab <eschwab@online.de>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
