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From 1d78f72cb5a387922870e2a54228be25f84f95f6 Mon Sep 17 00:00:00 2001
From: Phil Elwell <phil@raspberrypi.com>
Date: Tue, 16 Jun 2020 10:23:29 +0100
Subject: [PATCH] Revert "spi: spi-bcm2835: Disable forced software
CS"
This reverts commit 2697f0186db346176832b8eb79adaf5c874681e8.
See: https://github.com/raspberrypi/linux/pull/3687
---
drivers/spi/spi-bcm2835.c | 37 +++++++++++++++++++++++++++++++++++++
1 file changed, 37 insertions(+)
--- a/drivers/spi/spi-bcm2835.c
+++ b/drivers/spi/spi-bcm2835.c
@@ -1235,6 +1235,43 @@ static int bcm2835_spi_setup(struct spi_
return -EINVAL;
}
+ /*
+ * Translate native CS to GPIO
+ *
+ * FIXME: poking around in the gpiolib internals like this is
+ * not very good practice. Find a way to locate the real problem
+ * and fix it. Why is the GPIO descriptor in spi->cs_gpiod
+ * sometimes not assigned correctly? Erroneous device trees?
+ */
+
+ /* get the gpio chip for the base */
+ chip = gpiochip_find("pinctrl-bcm2835", chip_match_name);
+ if (!chip)
+ return 0;
+
+ /*
+ * Retrieve the corresponding GPIO line used for CS.
+ * The inversion semantics will be handled by the GPIO core
+ * code, so we pass GPIOS_OUT_LOW for "unasserted" and
+ * the correct flag for inversion semantics. The SPI_CS_HIGH
+ * on spi->mode cannot be checked for polarity in this case
+ * as the flag use_gpio_descriptors enforces SPI_CS_HIGH.
+ */
+ if (of_property_read_bool(spi->dev.of_node, "spi-cs-high"))
+ lflags = GPIO_ACTIVE_HIGH;
+ else
+ lflags = GPIO_ACTIVE_LOW;
+ spi->cs_gpiod = gpiochip_request_own_desc(chip, 8 - spi->chip_select,
+ DRV_NAME,
+ lflags,
+ GPIOD_OUT_LOW);
+ if (IS_ERR(spi->cs_gpiod))
+ return PTR_ERR(spi->cs_gpiod);
+
+ /* and set up the "mode" and level */
+ dev_info(&spi->dev, "setting up native-CS%i to use GPIO\n",
+ spi->chip_select);
+
return 0;
}
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