58 lines
1.9 KiB
Diff
58 lines
1.9 KiB
Diff
From c979072887ef70aab2ab6e71544853df71017925 Mon Sep 17 00:00:00 2001
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From: Phil Elwell <phil@raspberrypi.com>
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Date: Wed, 12 Jan 2022 08:23:28 +0000
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Subject: [PATCH] spi: gpio: Add sck-idle-input property
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The sck-idle-input property indicates that the spi-gpio driver should
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return the SCK line to an input when the chip select signals are
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inactive.
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Signed-off-by: Phil Elwell <phil@raspberrypi.com>
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---
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drivers/spi/spi-gpio.c | 13 +++++++++++--
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1 file changed, 11 insertions(+), 2 deletions(-)
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--- a/drivers/spi/spi-gpio.c
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+++ b/drivers/spi/spi-gpio.c
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@@ -35,6 +35,7 @@ struct spi_gpio {
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struct gpio_desc *sck;
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struct gpio_desc *miso;
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struct gpio_desc *mosi;
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+ bool sck_idle_input;
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struct gpio_desc **cs_gpios;
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};
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@@ -201,8 +202,12 @@ static void spi_gpio_chipselect(struct s
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struct spi_gpio *spi_gpio = spi_to_spi_gpio(spi);
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/* set initial clock line level */
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- if (is_active)
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- gpiod_set_value_cansleep(spi_gpio->sck, spi->mode & SPI_CPOL);
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+ if (is_active) {
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+ if (spi_gpio->sck_idle_input)
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+ gpiod_direction_output(spi_gpio->sck, spi->mode & SPI_CPOL);
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+ else
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+ gpiod_set_value_cansleep(spi_gpio->sck, spi->mode & SPI_CPOL);
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+ }
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/* Drive chip select line, if we have one */
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if (spi_gpio->cs_gpios) {
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@@ -211,6 +216,9 @@ static void spi_gpio_chipselect(struct s
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/* SPI chip selects are normally active-low */
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gpiod_set_value_cansleep(cs, (spi->mode & SPI_CS_HIGH) ? is_active : !is_active);
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}
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+
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+ if (spi_gpio->sck_idle_input && !is_active)
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+ gpiod_direction_input(spi_gpio->sck);
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}
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static int spi_gpio_setup(struct spi_device *spi)
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@@ -299,6 +307,7 @@ static int spi_gpio_request(struct devic
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if (IS_ERR(spi_gpio->miso))
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return PTR_ERR(spi_gpio->miso);
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+ spi_gpio->sck_idle_input = device_property_read_bool(dev, "sck-idle-input");
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spi_gpio->sck = devm_gpiod_get(dev, "sck", GPIOD_OUT_LOW);
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return PTR_ERR_OR_ZERO(spi_gpio->sck);
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}
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