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of_spi: add generic binding support to specify cs gpio

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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>
This commit is contained in:
Jean-Christophe PLAGNIOL-VILLARD
2012-11-15 20:19:57 +01:00
committed by Grant Likely
parent 15d0983f5c
commit 7431798490
3 changed files with 74 additions and 3 deletions
Download Patch File Download Diff File Expand all files Collapse all files

54
drivers/spi/spi.c
View File

@@ -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
*/