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From f58037ac49ec4233848397cf67f84afa97a3ab38 Mon Sep 17 00:00:00 2001
From: Phil Elwell <phil@raspberrypi.org>
Date: Wed, 24 Jun 2015 14:10:44 +0100
Subject: [PATCH] spi-bcm2835: Support pin groups other than 7-11
The spi-bcm2835 driver automatically uses GPIO chip-selects due to
some unreliability of the native ones. In doing so it chooses the
same pins as the native chip-selects would use, but the existing
code always uses pins 7 and 8, wherever the SPI function is mapped.
Search the pinctrl group assigned to the driver for pins that
correspond to native chip-selects, and use those for GPIO chip-
selects.
Signed-off-by: Phil Elwell <phil@raspberrypi.org>
---
drivers/spi/spi-bcm2835.c | 45 +++++++++++++++++++++++++++++++++++++--------
1 file changed, 37 insertions(+), 8 deletions(-)
--- a/drivers/spi/spi-bcm2835.c
+++ b/drivers/spi/spi-bcm2835.c
@@ -688,6 +688,8 @@ static int bcm2835_spi_setup(struct spi_
{
int err;
struct gpio_chip *chip;
+ struct device_node *pins;
+ u32 pingroup_index;
/*
* sanity checking the native-chipselects
*/
@@ -704,15 +706,42 @@ static int bcm2835_spi_setup(struct spi_
"setup: only two native chip-selects are supported\n");
return -EINVAL;
}
- /* now translate native cs to GPIO */
- /* get the gpio chip for the base */
- chip = gpiochip_find("pinctrl-bcm2835", chip_match_name);
- if (!chip)
- return 0;
+ /* now translate native cs to GPIO */
+ /* first look for chip select pins in the devices pin groups */
+ for (pingroup_index = 0;
+ (pins = of_parse_phandle(spi->master->dev.of_node,
+ "pinctrl-0",
+ pingroup_index)) != 0;
+ pingroup_index++) {
+ u32 pin;
+ u32 pin_index;
+ for (pin_index = 0;
+ of_property_read_u32_index(pins,
+ "brcm,pins",
+ pin_index,
+ &pin) == 0;
+ pin_index++) {
+ if (((spi->chip_select == 0) &&
+ ((pin == 8) || (pin == 36) || (pin == 46))) ||
+ ((spi->chip_select == 1) &&
+ ((pin == 7) || (pin == 35)))) {
+ spi->cs_gpio = pin;
+ break;
+ }
+ }
+ of_node_put(pins);
+ }
+ /* if that fails, assume GPIOs 7-11 are used */
+ if (!gpio_is_valid(spi->cs_gpio) ) {
+ /* get the gpio chip for the base */
+ chip = gpiochip_find("pinctrl-bcm2835", chip_match_name);
+ if (!chip)
+ return 0;
- /* and calculate the real CS */
- spi->cs_gpio = chip->base + 8 - spi->chip_select;
+ /* and calculate the real CS */
+ spi->cs_gpio = chip->base + 8 - spi->chip_select;
+ }
/* and set up the "mode" and level */
dev_info(&spi->dev, "setting up native-CS%i as GPIO %i\n",
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