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authorJean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>2012-11-15 23:19:57 +0400
committerGrant Likely <grant.likely@secretlab.ca>2012-11-22 03:25:33 +0400
commit743179849015dc71bb2ea63d8cd4bfa7fdfb4bc6 (patch)
treedcf0d554dd907740a5f4519355d4e896a94efd3b /drivers/spi
parent15d0983f5cc862facc8453a592220598a36d7f9d (diff)
downloadlinux-743179849015dc71bb2ea63d8cd4bfa7fdfb4bc6.tar.xz
of_spi: add generic binding support to specify cs gpio
This will allow to use gpio for chip select with no modification in the driver binding When use the cs-gpios, the gpio number will be passed via the cs_gpio field and the number of chip select will automatically increased with max(hw cs, gpio cs). So if for example the controller has 2 CS lines, and the cs-gpios property looks like this: cs-gpios = <&gpio1 0 0> <0> <&gpio1 1 0> <&gpio1 2 0>; Then it should be configured so that num_chipselect = 4 with the following mapping: cs0 : &gpio1 0 0 cs1 : native cs2 : &gpio1 1 0 cs3 : &gpio1 2 0 Signed-off-by: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com> Cc: devicetree-discuss@lists.ozlabs.org Cc: spi-devel-general@lists.sourceforge.net Signed-off-by: Richard Genoud <richard.genoud@gmail.com> [grant.likely: fixed up type of cs count so min() can do type checking] Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
Diffstat (limited to 'drivers/spi')
-rw-r--r--drivers/spi/spi.c54
1 files changed, 51 insertions, 3 deletions
diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c
index 84c2861d6f4d..1587a4a5ff41 100644
--- a/drivers/spi/spi.c
+++ b/drivers/spi/spi.c
@@ -30,6 +30,7 @@
#include <linux/slab.h>
#include <linux/mod_devicetable.h>
#include <linux/spi/spi.h>
+#include <linux/of_gpio.h>
#include <linux/pm_runtime.h>
#include <linux/export.h>
#include <linux/sched.h>
@@ -327,6 +328,7 @@ struct spi_device *spi_alloc_device(struct spi_master *master)
spi->dev.parent = &master->dev;
spi->dev.bus = &spi_bus_type;
spi->dev.release = spidev_release;
+ spi->cs_gpio = -EINVAL;
device_initialize(&spi->dev);
return spi;
}
@@ -344,15 +346,16 @@ EXPORT_SYMBOL_GPL(spi_alloc_device);
int spi_add_device(struct spi_device *spi)
{
static DEFINE_MUTEX(spi_add_lock);
- struct device *dev = spi->master->dev.parent;
+ struct spi_master *master = spi->master;
+ struct device *dev = master->dev.parent;
struct device *d;
int status;
/* Chipselects are numbered 0..max; validate. */
- if (spi->chip_select >= spi->master->num_chipselect) {
+ if (spi->chip_select >= master->num_chipselect) {
dev_err(dev, "cs%d >= max %d\n",
spi->chip_select,
- spi->master->num_chipselect);
+ master->num_chipselect);
return -EINVAL;
}
@@ -376,6 +379,9 @@ int spi_add_device(struct spi_device *spi)
goto done;
}
+ if (master->cs_gpios)
+ spi->cs_gpio = master->cs_gpios[spi->chip_select];
+
/* Drivers may modify this initial i/o setup, but will
* normally rely on the device being setup. Devices
* using SPI_CS_HIGH can't coexist well otherwise...
@@ -946,6 +952,44 @@ struct spi_master *spi_alloc_master(struct device *dev, unsigned size)
}
EXPORT_SYMBOL_GPL(spi_alloc_master);
+#ifdef CONFIG_OF
+static int of_spi_register_master(struct spi_master *master)
+{
+ u16 nb;
+ int i, *cs;
+ struct device_node *np = master->dev.of_node;
+
+ if (!np)
+ return 0;
+
+ nb = of_gpio_named_count(np, "cs-gpios");
+ master->num_chipselect = max(nb, master->num_chipselect);
+
+ if (nb < 1)
+ return 0;
+
+ cs = devm_kzalloc(&master->dev,
+ sizeof(int) * master->num_chipselect,
+ GFP_KERNEL);
+ master->cs_gpios = cs;
+
+ if (!master->cs_gpios)
+ return -ENOMEM;
+
+ memset(cs, -EINVAL, master->num_chipselect);
+
+ for (i = 0; i < nb; i++)
+ cs[i] = of_get_named_gpio(np, "cs-gpios", i);
+
+ return 0;
+}
+#else
+static int of_spi_register_master(struct spi_master *master)
+{
+ return 0;
+}
+#endif
+
/**
* spi_register_master - register SPI master controller
* @master: initialized master, originally from spi_alloc_master()
@@ -977,6 +1021,10 @@ int spi_register_master(struct spi_master *master)
if (!dev)
return -ENODEV;
+ status = of_spi_register_master(master);
+ if (status)
+ return status;
+
/* even if it's just one always-selected device, there must
* be at least one chipselect
*/