diff options
| -rw-r--r-- | drivers/mfd/mfd-core.c | 64 | ||||
| -rw-r--r-- | include/linux/mfd/core.h | 14 |
2 files changed, 73 insertions, 5 deletions
diff --git a/drivers/mfd/mfd-core.c b/drivers/mfd/mfd-core.c index 01115f686df..ca789f88230 100644 --- a/drivers/mfd/mfd-core.c +++ b/drivers/mfd/mfd-core.c @@ -18,6 +18,43 @@ #include <linux/pm_runtime.h> #include <linux/slab.h> +int mfd_shared_cell_enable(struct platform_device *pdev) +{ + const struct mfd_cell *cell = mfd_get_cell(pdev); + int err = 0; + + /* only call enable hook if the cell wasn't previously enabled */ + if (atomic_inc_return(cell->usage_count) == 1) + err = cell->enable(pdev); + + /* if the enable hook failed, decrement counter to allow retries */ + if (err) + atomic_dec(cell->usage_count); + + return err; +} +EXPORT_SYMBOL(mfd_shared_cell_enable); + +int mfd_shared_cell_disable(struct platform_device *pdev) +{ + const struct mfd_cell *cell = mfd_get_cell(pdev); + int err = 0; + + /* only disable if no other clients are using it */ + if (atomic_dec_return(cell->usage_count) == 0) + err = cell->disable(pdev); + + /* if the disable hook failed, increment to allow retries */ + if (err) + atomic_inc(cell->usage_count); + + /* sanity check; did someone call disable too many times? */ + WARN_ON(atomic_read(cell->usage_count) < 0); + + return err; +} +EXPORT_SYMBOL(mfd_shared_cell_disable); + static int mfd_add_device(struct device *parent, int id, const struct mfd_cell *cell, struct resource *mem_base, @@ -96,14 +133,22 @@ fail_alloc: } 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) { int i; int ret = 0; + atomic_t *cnts; + + /* initialize reference counting for all cells */ + cnts = kcalloc(sizeof(*cnts), n_devs, GFP_KERNEL); + if (!cnts) + return -ENOMEM; for (i = 0; i < n_devs; i++) { + atomic_set(&cnts[i], 0); + cells[i].usage_count = &cnts[i]; ret = mfd_add_device(parent, id, cells + i, mem_base, irq_base); if (ret) break; @@ -116,15 +161,26 @@ int mfd_add_devices(struct device *parent, int id, } EXPORT_SYMBOL(mfd_add_devices); -static int mfd_remove_devices_fn(struct device *dev, void *unused) +static int mfd_remove_devices_fn(struct device *dev, void *c) { - platform_device_unregister(to_platform_device(dev)); + struct platform_device *pdev = to_platform_device(dev); + const struct mfd_cell *cell = mfd_get_cell(pdev); + atomic_t **usage_count = c; + + /* find the base address of usage_count pointers (for freeing) */ + if (!*usage_count || (cell->usage_count < *usage_count)) + *usage_count = cell->usage_count; + + platform_device_unregister(pdev); return 0; } void mfd_remove_devices(struct device *parent) { - device_for_each_child(parent, NULL, mfd_remove_devices_fn); + atomic_t *cnts = NULL; + + device_for_each_child(parent, &cnts, mfd_remove_devices_fn); + kfree(cnts); } EXPORT_SYMBOL(mfd_remove_devices); diff --git a/include/linux/mfd/core.h b/include/linux/mfd/core.h index 71cd1f983cc..22a2f5ebd9d 100644 --- a/include/linux/mfd/core.h +++ b/include/linux/mfd/core.h @@ -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); @@ -51,6 +54,15 @@ struct mfd_cell { }; /* + * 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); |