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.ardel...@analog.com>
---
drivers/spi/spi.c | 50 ++++++++++++++++++++++++++++++++++++++++-
include/linux/spi/spi.h | 5 +++++
2 files changed, 54 insertions(+), 1 deletion(-)
diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c
index 54d00c0a26d2..acbbfee837ed 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
@@ -3144,6 +3158,11 @@ int spi_setup(struct spi_device *spi)
}
EXPORT_SYMBOL_GPL(spi_setup);
+static inline bool _spi_delay_clock_cycles(struct spi_delay *d)
+{
+ return d && d->unit == SPI_DELAY_UNIT_SCK;
+}
+
/**
* spi_set_cs_timing - configure CS setup, hold, and inactive delays
* @spi: the device that requires specific CS timing configuration
@@ -3156,10 +3175,39 @@ 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 (_spi_delay_clock_cycles(setup) ||
+ _spi_delay_clock_cycles(hold) ||
+ _spi_delay_clock_cycles(inactive)) {
+ 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);
diff --git a/include/linux/spi/spi.h b/include/linux/spi/spi.h
index 292e752ce34a..def49a76299f 100644
--- a/include/linux/spi/spi.h
+++ b/include/linux/spi/spi.h
@@ -602,6 +602,11 @@ struct spi_controller {
/* Optimized handlers for SPI memory-like operations. */
const struct spi_controller_mem_ops *mem_ops;
+ /* CS delays */
+ struct spi_delay cs_setup;
+ struct spi_delay cs_hold;
+ struct spi_delay cs_inactive;
+
/* gpio chip select */
int *cs_gpios;
struct gpio_desc **cs_gpiods;
--
2.20.1
