From 1e29af62f2b285bd18685da93c3ce8c33ca2d1db Mon Sep 17 00:00:00 2001 From: Andres Salomon Date: Thu, 17 Feb 2011 19:07:34 -0800 Subject: mfd: Add refcounting support to mfd_cells 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 Signed-off-by: Samuel Ortiz --- drivers/mfd/mfd-core.c | 64 ++++++++++++++++++++++++++++++++++++++++++++++---- 1 file changed, 60 insertions(+), 4 deletions(-) (limited to 'drivers/mfd/mfd-core.c') diff --git a/drivers/mfd/mfd-core.c b/drivers/mfd/mfd-core.c index 01115f686dfa..ca789f882305 100644 --- a/drivers/mfd/mfd-core.c +++ b/drivers/mfd/mfd-core.c @@ -18,6 +18,43 @@ #include #include +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); -- cgit v1.2.3