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mfd: Add refcounting support to mfd_cells

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This provides convenience functions for sharing of cells across
multiple mfd clients.  Mfd drivers can provide enable/disable hooks
to actually tweak the hardware, and clients can call
mfd_shared_cell_{en,dis}able without having to worry about whether
or not another client happens to have enabled or disabled the
cell/hardware.

Note that this is purely optional; drivers can continue to use
the mfd_cell's enable/disable hooks for their own purposes, if
desired.

Signed-off-by: Andres Salomon <dilinger@queued.net>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>
This commit is contained in:
Andres Salomon
2011-02-17 19:07:34 -08:00
committed by Samuel Ortiz
parent dcb50e83bb
commit 1e29af62f2
2 changed files with 73 additions and 5 deletions
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14
include/linux/mfd/core.h
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@ -25,8 +25,11 @@ struct mfd_cell {
const char *name;
int id;
/* refcounting for multiple drivers to use a single cell */
atomic_t *usage_count;
int (*enable)(struct platform_device *dev);
int (*disable)(struct platform_device *dev);
int (*suspend)(struct platform_device *dev);
int (*resume)(struct platform_device *dev);
@ -50,6 +53,15 @@ struct mfd_cell {
bool pm_runtime_no_callbacks;
};
/*
* Convenience functions for clients using shared cells. Refcounting
* happens automatically, with the cell's enable/disable callbacks
* being called only when a device is first being enabled or no other
* clients are making use of it.
*/
extern int mfd_shared_cell_enable(struct platform_device *pdev);
extern int mfd_shared_cell_disable(struct platform_device *pdev);
/*
* Given a platform device that's been created by mfd_add_devices(), fetch
* the mfd_cell that created it.
@ -69,7 +81,7 @@ static inline void *mfd_get_data(struct platform_device *pdev)
}
extern int mfd_add_devices(struct device *parent, int id,
const struct mfd_cell *cells, int n_devs,
struct mfd_cell *cells, int n_devs,
struct resource *mem_base,
int irq_base);