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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>
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platform_get_irq returns -ENXIO on failure, so !irq was probably
always true. Make irq a signed variable and compare irq <= 0. Note
that a return value of zero is still handled as error even though this
could mean irq0.
This is a followup to 305b3228f9ff4d59f49e6d34a7034d44ee8ce2f0 that
changed the return value of platform_get_irq from 0 to -ENXIO on error.
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Acked-by: Anton Vorontsov <avorontsov@ru.mvista.com>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
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* 'next-spi' of git://git.secretlab.ca/git/linux-2.6:
spi: spi_txx9.c: use resource_size()
spi: spi_sh_sci.c: use resource_size()
spi: spi_mpc8xxx.c: use resource_size()
spi: spi_bfin5xx.c: use resource_size()
spi: atmel_spi.c: use resource_size()
spi: Add s3c64xx SPI Controller driver
atmel_spi: fix dma addr calculation for len > BUFFER_SIZE
spi_s3c24xx: add FIQ pseudo-DMA support
spi: controller driver for Designware SPI core
spidev: add proper section markers
spidev: use DECLARE_BITMAP instead of declaring the array
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Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Cc: David Brownell <dbrownell@users.sourceforge.net>
Cc: Kumar Gala <galak@kernel.crashing.org>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
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* 'next-spi' of git://git.secretlab.ca/git/linux-2.6: (23 commits)
spi: fix probe/remove section markings
Add OMAP spi100k driver
spi-imx: don't access struct device directly but use dev_get_platdata
spi-imx: Add mx25 support
spi-imx: use positive logic to distinguish cpu variants
spi-imx: correct check for platform_get_irq failing
ARM: NUC900: Add spi driver support for nuc900
spi: SuperH MSIOF SPI Master driver V2
spi: fix spidev compilation failure when VERBOSE is defined
spi/au1550_spi: fix setupxfer not to override cfg with zeros
spi/mpc8xxx: don't use __exit_p to wrap plat_mpc8xxx_spi_remove
spi/i.MX: fix broken error handling for gpio_request
spi/i.mx: drain MXC SPI transfer buffer when probing device
MAINTAINERS: add SPI co-maintainer.
spi/xilinx_spi: fix incorrect casting
spi/mpc52xx-spi: minor cleanups
xilinx_spi: add a platform driver using the xilinx_spi common module.
xilinx_spi: add support for the DS570 IP.
xilinx_spi: Switch to iomem functions and support little endian.
xilinx_spi: Split into of driver and generic part.
...
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The function plat_mpc8xxx_spi_remove is defined using __devexit, so don't
use __exit_p but __devexit_p to wrap it.
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
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Commit 87ec0e98cfdd8b68da6a7f9e70142ffc0e404fbb in kumar's next branch
broke one of my test configs since it looks like Anton forgot about
that mpc832x_rdb platform which still uses the old style probing for
the SPI stuff.
I'll let them do a cleaner fix that probably involves changing the
probing method and getting rid of the platform device but for now
this will do to fix it.
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
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This patch adds QE buffer descriptors mode support for the
spi_mpc8xxx driver, and as a side effect we now support CPM1
and CPM2 SPI controllers.
That means that today we support almost all MPC SPI controllers:
- MPC834x-style controllers (support PIO mode only);
- CPM1 and CPM2 controllers (support DMA mode only);
- QE SPI controllers in CPU mode (PIO mode with shift quirks);
- QE SPI controllers in buffer descriptors (DMA) mode;
The only controller we don't currently support is a newer eSPI
(with a dedicated chip selects and a bit different registers map).
Signed-off-by: Anton Vorontsov <avorontsov@ru.mvista.com>
Acked-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>
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Soon there will be more flags introduced in subsequent patches, so
let's turn qe_mode into flags.
Also introduce mpc8xxx_spi_strmode() and print current SPI mode.
Signed-off-by: Anton Vorontsov <avorontsov@ru.mvista.com>
Acked-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>
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We'll add more steps soon, so get rid of the duplication.
Signed-off-by: Anton Vorontsov <avorontsov@ru.mvista.com>
Acked-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>
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This patch fixes the following warning:
CC drivers/spi/spi_mpc8xxx.o
spi_mpc8xxx.c: In function 'of_mpc8xxx_spi_probe':
spi_mpc8xxx.c:681: warning: 'ret' may be used uninitialized in this function
Signed-off-by: Anton Vorontsov <avorontsov@ru.mvista.com>
Acked-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>
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Since we renamed the file, we might want to rename the file internals too.
Though we don't bother with changing platform driver name and platform
module alias. The stuff is legacy and hopefully we'll remove it soon.
Suggested-by: Kumar Gala <galak@kernel.crashing.org>
Signed-off-by: Anton Vorontsov <avorontsov@ru.mvista.com>
Cc: David Brownell <david-b@pacbell.net>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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The driver handles MPC83xx, MPC85xx and MPC86xx SPI controllers, so rename
the file for clarity.
Suggested-by: Kumar Gala <galak@kernel.crashing.org>
Signed-off-by: Anton Vorontsov <avorontsov@ru.mvista.com>
Cc: Kumar Gala <galak@gate.crashing.org>
Cc: David Brownell <david-b@pacbell.net>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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