[PATCH 2/3] of_spi: add generic binding support to specify ncs gpio
Jean-Christophe PLAGNIOL-VILLARD
plagnioj at jcrosoft.com
Fri Feb 10 03:14:36 EST 2012
This will allow to use gpio for chip select with no modification in the
driver binding
When use the ncs-gpios, the gpio number will be passed via the controller_data
and the number of chip select will automatically increased.
Signed-off-by: Jean-Christophe PLAGNIOL-VILLARD <plagnioj at jcrosoft.com>
Cc: devicetree-discuss at lists.ozlabs.org
Cc: spi-devel-general at lists.sourceforge.net
---
Documentation/devicetree/bindings/spi/spi-bus.txt | 6 +++
drivers/of/of_spi.c | 27 ++++++++---
drivers/spi/spi.c | 51 +++++++++++++++++++-
include/linux/spi/spi.h | 5 ++
4 files changed, 78 insertions(+), 11 deletions(-)
diff --git a/Documentation/devicetree/bindings/spi/spi-bus.txt b/Documentation/devicetree/bindings/spi/spi-bus.txt
index e782add..5a24729 100644
--- a/Documentation/devicetree/bindings/spi/spi-bus.txt
+++ b/Documentation/devicetree/bindings/spi/spi-bus.txt
@@ -12,6 +12,7 @@ The SPI master node requires the following properties:
- #size-cells - should be zero.
- compatible - name of SPI bus controller following generic names
recommended practice.
+- ncs-gpios - (optional) gpios chip select.
No other properties are required in the SPI bus node. It is assumed
that a driver for an SPI bus device will understand that it is an SPI bus.
However, the binding does not attempt to define the specific method for
@@ -21,6 +22,8 @@ assumption that board specific platform code will be used to manage
chip selects. Individual drivers can define additional properties to
support describing the chip select layout.
+If ncs-gpios is used the number of chip select will automatically increased.
+
SPI slave nodes must be children of the SPI master node and can
contain the following properties.
- reg - (required) chip select address of device.
@@ -34,6 +37,9 @@ contain the following properties.
- spi-cs-high - (optional) Empty property indicating device requires
chip select active high
+If a gpio chipselect is used for the SPI slave the gpio number will be passed
+via the controller_data
+
SPI example for an MPC5200 SPI bus:
spi at f00 {
#address-cells = <1>;
diff --git a/drivers/of/of_spi.c b/drivers/of/of_spi.c
index 6dbc074..0d41407 100644
--- a/drivers/of/of_spi.c
+++ b/drivers/of/of_spi.c
@@ -12,6 +12,7 @@
#include <linux/spi/spi.h>
#include <linux/of_irq.h>
#include <linux/of_spi.h>
+#include <linux/of_gpio.h>
/**
* of_register_spi_devices - Register child devices onto the SPI bus
@@ -27,6 +28,7 @@ void of_register_spi_devices(struct spi_master *master)
const __be32 *prop;
int rc;
int len;
+ int ncs_pin;
if (!master->dev.of_node)
return;
@@ -50,15 +52,24 @@ void of_register_spi_devices(struct spi_master *master)
continue;
}
- /* Device address */
- prop = of_get_property(nc, "reg", &len);
- if (!prop || len < sizeof(*prop)) {
- dev_err(&master->dev, "%s has no 'reg' property\n",
- nc->full_name);
- spi_dev_put(spi);
- continue;
+ /* ncs gpio */
+ ncs_pin = of_get_named_gpio(nc, "ncs-gpio", 0);
+
+ if (gpio_is_valid(ncs_pin)) {
+ spi->controller_data = (void *)ncs_pin;
+ spi->chip_select = master->num_chipselect;
+ master->num_chipselect++;
+ } else {
+ /* Device address */
+ prop = of_get_property(nc, "reg", &len);
+ if (!prop || len < sizeof(*prop)) {
+ dev_err(&master->dev, "%s has no 'reg' property\n",
+ nc->full_name);
+ spi_dev_put(spi);
+ continue;
+ }
+ spi->chip_select = be32_to_cpup(prop);
}
- spi->chip_select = be32_to_cpup(prop);
/* Mode (clock phase/polarity/etc.) */
if (of_find_property(nc, "spi-cpha", NULL))
diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c
index e2f4ca0..1f5ffa6 100644
--- a/drivers/spi/spi.c
+++ b/drivers/spi/spi.c
@@ -28,6 +28,7 @@
#include <linux/mod_devicetable.h>
#include <linux/spi/spi.h>
#include <linux/of_spi.h>
+#include <linux/of_gpio.h>
#include <linux/pm_runtime.h>
#include <linux/export.h>
@@ -339,15 +340,16 @@ 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;
}
@@ -371,6 +373,13 @@ int spi_add_device(struct spi_device *spi)
goto done;
}
+ if (master->num_gpio_chipselect &&
+ spi->chip_select >= master->first_gpio_chipselect) {
+ int num = spi->chip_select = master->first_gpio_chipselect;
+
+ spi->controller_data = (void*)master->chipselect_gpios[num];
+ }
+
/* 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...
@@ -562,6 +571,38 @@ struct spi_master *spi_alloc_master(struct device *dev, unsigned size)
}
EXPORT_SYMBOL_GPL(spi_alloc_master);
+static int of_spi_register_master(struct spi_master *master)
+{
+ int nb, i;
+ int *cs;
+ struct device_node *np = master->dev.of_node;
+
+ if (!np)
+ return 0;
+
+ nb = of_gpio_named_count(np, "ncs-gpios");
+
+ if (nb < 1)
+ return 0;
+
+ master->chipselect_gpios = kzalloc(sizeof(int) * nb, GFP_KERNEL);
+
+ if (!master->chipselect_gpios)
+ return -ENOMEM;
+
+ master->first_gpio_chipselect = master->num_chipselect;
+ master->num_chipselect += nb;
+ master->num_gpio_chipselect = nb;
+
+ for (i = 0; i < nb; i++) {
+ cs = &master->chipselect_gpios[i];
+
+ *cs = of_get_named_gpio(np, "ncs-gpios", i);
+ }
+
+ return 0;
+}
+
/**
* spi_register_master - register SPI master controller
* @master: initialized master, originally from spi_alloc_master()
@@ -593,6 +634,10 @@ 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
*/
diff --git a/include/linux/spi/spi.h b/include/linux/spi/spi.h
index 176fce9..d21c267 100644
--- a/include/linux/spi/spi.h
+++ b/include/linux/spi/spi.h
@@ -318,6 +318,11 @@ struct spi_master {
/* called on release() to free memory provided by spi_master */
void (*cleanup)(struct spi_device *spi);
+
+ /* gpio chip select */
+ int *chipselect_gpios;
+ int first_gpio_chipselect;
+ int num_gpio_chipselect;
};
static inline void *spi_master_get_devdata(struct spi_master *master)
--
1.7.7
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