From 25093bdeb6bcae728e12e3795261dbd3677060a9 Mon Sep 17 00:00:00 2001 From: Alexandru Ardelean Date: Thu, 26 Sep 2019 13:51:43 +0300 Subject: 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 Link: https://lore.kernel.org/r/20190926105147.7839-16-alexandru.ardelean@analog.com Signed-off-by: Mark Brown --- drivers/spi/spi.c | 45 ++++++++++++++++++++++++++++++++++++++++++++- include/linux/spi/spi.h | 5 +++++ 2 files changed, 49 insertions(+), 1 deletion(-) 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); diff --git a/include/linux/spi/spi.h b/include/linux/spi/spi.h index f9b4ba2db08d..cfd87b18f077 100644 --- a/include/linux/spi/spi.h +++ b/include/linux/spi/spi.h @@ -609,6 +609,11 @@ 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; -- cgit v1.2.3