powerpc/qe: Implement QE Pin Multiplexing API

With this API we're able to set a QE pin to the GPIO mode or a dedicated
peripheral function.

The API relies on the fact that QE gpio controllers are registered. If
they aren't, the API won't work (gracefully though).

There is one caveat though: if anybody occupied the node->data before us,
or overwrote it, then bad things will happen. Luckily this is all in the
platform code that we fully control, so this should never happen.

I could implement more checks (for example we could create a list of
successfully registered QE controllers, and compare the node->data in the
qe_pin_request()), but this is unneeded if nobody is going to do silly
things behind our back.

Signed-off-by: Anton Vorontsov <avorontsov@ru.mvista.com>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>

1 files changed, 21 insertions, 0 deletions

diff --git a/arch/powerpc/include/asm/qe.h b/arch/powerpc/include/asm/qe.h
index edee15d269ea..32274407b93a 100644
--- a/arch/powerpc/include/asm/qe.h
+++ b/arch/powerpc/include/asm/qe.h
@@ -17,6 +17,8 @@
 #ifdef __KERNEL__
 
 #include <linux/spinlock.h>
+#include <linux/errno.h>
+#include <linux/err.h>
 #include <asm/cpm.h>
 #include <asm/immap_qe.h>
 
@@ -112,6 +114,25 @@ extern int par_io_config_pin(u8 port, u8 pin, int dir, int open_drain,
 			     int assignment, int has_irq);
 extern int par_io_data_set(u8 port, u8 pin, u8 val);
 
+/*
+ * Pin multiplexing functions.
+ */
+struct qe_pin;
+#ifdef CONFIG_QE_GPIO
+extern struct qe_pin *qe_pin_request(struct device_node *np, int index);
+extern void qe_pin_free(struct qe_pin *qe_pin);
+extern void qe_pin_set_gpio(struct qe_pin *qe_pin);
+extern void qe_pin_set_dedicated(struct qe_pin *pin);
+#else
+static inline struct qe_pin *qe_pin_request(struct device_node *np, int index)
+{
+	return ERR_PTR(-ENOSYS);
+}
+static inline void qe_pin_free(struct qe_pin *qe_pin) {}
+static inline void qe_pin_set_gpio(struct qe_pin *qe_pin) {}
+static inline void qe_pin_set_dedicated(struct qe_pin *pin) {}
+#endif /* CONFIG_QE_GPIO */
+
 /* QE internal API */
 int qe_issue_cmd(u32 cmd, u32 device, u8 mcn_protocol, u32 cmd_input);
 enum qe_clock qe_clock_source(const char *source);