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authorAlexandru Ardelean <alexandru.ardelean@analog.com>2019-09-26 12:51:43 +0200
committerMark Brown <broonie@kernel.org>2019-10-15 12:46:12 +0200
commit25093bdeb6bcae728e12e3795261dbd3677060a9 (patch)
tree919f7a6c5ac4f3bea9bf63ed8259ef0703940cb2 /drivers/spi
parentspi: tegra114: change format for `spi_set_cs_timing()` function (diff)
downloadlinux-25093bdeb6bcae728e12e3795261dbd3677060a9.tar.xz
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.c45
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);