On Thu, Nov 26, 2009 at 20:17:35, Grant Likely wrote:
[...]
> spi-cs-high is definitely not a complete solution, but it isn't
> actively evil either. Plus it is documented and (presumably) in
> active use. so support for it should not be dropped.
>
> Regardless, there needs to be a library function for parsing all the
> SPI child nodes and returning the active state for each GPIO chip
> select. All the code for parsing the old spi-cs-high properties can
> be contained in the same place as a new yet-to-be-defined bus node cs
> polarity property. The rework to the driver itself is not ugly.
>
The following patch adds a function to get the active state of the chip select
of a SPI device by looking for the 'spi-cs-high' property in the associated
device
tree node.
This function is used by the spi_mpc8xxx driver to set a proper initial value
to the associated GPIOs.
Signed-off-by: Torsten Fleischer <to-fleisc...@t-online.de>
---
diff -ruN linux-2.6.32_orig//drivers/of/of_spi.c
linux-2.6.32/drivers/of/of_spi.c
--- linux-2.6.32_orig//drivers/of/of_spi.c 2009-12-03 04:51:21.000000000
+0100
+++ linux-2.6.32/drivers/of/of_spi.c 2009-12-09 12:37:01.000000000 +0100
@@ -10,6 +10,49 @@
#include <linux/device.h>
#include <linux/spi/spi.h>
#include <linux/of_spi.h>
+#include <linux/errno.h>
+
+/**
+ * of_get_spi_cs_active_state - Gets the chip select's active state of a SPI
+ * child devices.
+ * @np: parent node of the SPI device nodes
+ * @index: index/address of the SPI device (refers to the 'reg' property)
+ * @cs_active: pointer to return the chip select's active state
+ * (true = active high; false = active low)
+ *
+ * Returns 0 on success; negative errno on failure
+ */
+int of_get_spi_cs_active_state(struct device_node *np, int index, bool
*cs_active)
+{
+ struct device_node *child;
+ const int *prop;
+ int len;
+ bool active = 0;
+
+ /* search for the matching SPI device */
+ for_each_child_of_node(np, child) {
+ prop = of_get_property(child, "reg", &len);
+ if (!prop || len < sizeof(*prop)) {
+ /* property 'reg' not available (not an error) */
+ continue;
+ }
+
+ if ( *prop == index ) {
+ /* matching device found */
+ if (of_find_property(child, "spi-cs-high", NULL))
+ active = 1;
+
+ if (cs_active)
+ *cs_active = active;
+
+ return 0;
+ }
+ }
+
+ return -ENODEV;
+}
+EXPORT_SYMBOL(of_get_spi_cs_active_state);
+
/**
* of_register_spi_devices - Register child devices onto the SPI bus
diff -ruN linux-2.6.32_orig//drivers/spi/spi_mpc8xxx.c
linux-2.6.32/drivers/spi/spi_mpc8xxx.c
--- linux-2.6.32_orig//drivers/spi/spi_mpc8xxx.c 2009-12-03
04:51:21.000000000 +0100
+++ linux-2.6.32/drivers/spi/spi_mpc8xxx.c 2009-12-09 12:50:36.000000000
+0100
@@ -705,6 +705,7 @@
for (; i < ngpios; i++) {
int gpio;
enum of_gpio_flags flags;
+ bool astate;
gpio = of_get_gpio_flags(np, i, &flags);
if (!gpio_is_valid(gpio)) {
@@ -721,8 +722,15 @@
pinfo->gpios[i] = gpio;
pinfo->alow_flags[i] = flags & OF_GPIO_ACTIVE_LOW;
+ ret = of_get_spi_cs_active_state(np, i, &astate);
+ if (ret) {
+ dev_err(dev, "can't get cs active state of device "
+ "#%d: %d\n", i, ret);
+ goto err_loop;
+ }
+
ret = gpio_direction_output(pinfo->gpios[i],
- pinfo->alow_flags[i]);
+ pinfo->alow_flags[i] ^ !astate);
if (ret) {
dev_err(dev, "can't set output direction for gpio "
"#%d: %d\n", i, ret);
diff -ruN linux-2.6.32_orig//include/linux/of_spi.h
linux-2.6.32/include/linux/of_spi.h
--- linux-2.6.32_orig//include/linux/of_spi.h 2009-12-03 04:51:21.000000000
+0100
+++ linux-2.6.32/include/linux/of_spi.h 2009-12-09 12:36:48.000000000 +0100
@@ -15,4 +15,7 @@
extern void of_register_spi_devices(struct spi_master *master,
struct device_node *np);
+extern int of_get_spi_cs_active_state(struct device_node *np,
+ int index, bool *cs_active);
+
#endif /* __LINUX_OF_SPI */
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