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powerpc/qe: Implement QE Pin Multiplexing API

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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>
This commit is contained in:
Anton Vorontsov
2008-12-03 22:27:38 +03:00
committed by Kumar Gala
parent 78c7705037
commit 1b9e89046c
2 changed files with 216 additions and 0 deletions
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21
arch/powerpc/include/asm/qe.h
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@@ -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);