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author | Alexandru Ardelean <alexandru.ardelean@analog.com> | 2019-09-26 13:51:43 +0300 |
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committer | Mark Brown <broonie@kernel.org> | 2019-10-15 11:46:12 +0100 |
commit | 25093bdeb6bcae728e12e3795261dbd3677060a9 (patch) | |
tree | 919f7a6c5ac4f3bea9bf63ed8259ef0703940cb2 /drivers/spi | |
parent | 8105936684681195d9073880b06a123b2e316811 (diff) | |
download | linux-25093bdeb6bcae728e12e3795261dbd3677060a9.tar.gz linux-25093bdeb6bcae728e12e3795261dbd3677060a9.tar.bz2 linux-25093bdeb6bcae728e12e3795261dbd3677060a9.zip |
spi: implement SW control for CS times
This change implements CS control for setup, hold & inactive delays.
The `cs_setup` delay is completely new, and can help with cases where
asserting the CS, also brings the device out of power-sleep, where there
needs to be a longer (than usual), before transferring data.
The `cs_hold` time can overlap with the `delay` (or `delay_usecs`) from an
SPI transfer. The main difference is that `cs_hold` implies that CS will be
de-asserted.
The `cs_inactive` delay does not have a clear use-case yet. It has been
implemented mostly because the `spi_set_cs_timing()` function implements
it. To some degree, this could overlap or replace `cs_change_delay`, but
this will require more consideration/investigation in the future.
All these delays have been added to the `spi_controller` struct, as they
would typically be configured by calling `spi_set_cs_timing()` after an
`spi_setup()` call.
Software-mode for CS control, implies that the `set_cs_timing()` hook has
not been provided for the `spi_controller` object.
Signed-off-by: Alexandru Ardelean <alexandru.ardelean@analog.com>
Link: https://lore.kernel.org/r/20190926105147.7839-16-alexandru.ardelean@analog.com
Signed-off-by: Mark Brown <broonie@kernel.org>
Diffstat (limited to 'drivers/spi')
-rw-r--r-- | drivers/spi/spi.c | 45 |
1 files changed, 44 insertions, 1 deletions
diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c index 6beeb363515c..21628b0728f1 100644 --- a/drivers/spi/spi.c +++ b/drivers/spi/spi.c @@ -775,6 +775,15 @@ int spi_register_board_info(struct spi_board_info const *info, unsigned n) static void spi_set_cs(struct spi_device *spi, bool enable) { + bool enable1 = enable; + + if (!spi->controller->set_cs_timing) { + if (enable1) + spi_delay_exec(&spi->controller->cs_setup, NULL); + else + spi_delay_exec(&spi->controller->cs_hold, NULL); + } + if (spi->mode & SPI_CS_HIGH) enable = !enable; @@ -800,6 +809,11 @@ static void spi_set_cs(struct spi_device *spi, bool enable) } else if (spi->controller->set_cs) { spi->controller->set_cs(spi, !enable); } + + if (!spi->controller->set_cs_timing) { + if (!enable1) + spi_delay_exec(&spi->controller->cs_inactive, NULL); + } } #ifdef CONFIG_HAS_DMA @@ -3278,10 +3292,39 @@ EXPORT_SYMBOL_GPL(spi_setup); int spi_set_cs_timing(struct spi_device *spi, struct spi_delay *setup, struct spi_delay *hold, struct spi_delay *inactive) { + size_t len; + if (spi->controller->set_cs_timing) return spi->controller->set_cs_timing(spi, setup, hold, inactive); - return -ENOTSUPP; + + if ((setup && setup->unit == SPI_DELAY_UNIT_SCK) || + (hold && hold->unit == SPI_DELAY_UNIT_SCK) || + (inactive && inactive->unit == SPI_DELAY_UNIT_SCK)) { + dev_err(&spi->dev, + "Clock-cycle delays for CS not supported in SW mode\n"); + return -ENOTSUPP; + } + + len = sizeof(struct spi_delay); + + /* copy delays to controller */ + if (setup) + memcpy(&spi->controller->cs_setup, setup, len); + else + memset(&spi->controller->cs_setup, 0, len); + + if (hold) + memcpy(&spi->controller->cs_hold, hold, len); + else + memset(&spi->controller->cs_hold, 0, len); + + if (inactive) + memcpy(&spi->controller->cs_inactive, inactive, len); + else + memset(&spi->controller->cs_inactive, 0, len); + + return 0; } EXPORT_SYMBOL_GPL(spi_set_cs_timing); |