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authorAndres Salomon <dilinger@queued.net>2011-02-17 19:07:34 -0800
committerSamuel Ortiz <sameo@linux.intel.com>2011-03-23 10:41:58 +0100
commit1e29af62f2b285bd18685da93c3ce8c33ca2d1db (patch)
tree662545398e04cfb5b10fa4b13810d47ddd003c98 /drivers/mfd/mfd-core.c
parentdcb50e83bb86d66d3554ba9c365488669c84d037 (diff)
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 <dilinger@queued.net> Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>
Diffstat (limited to 'drivers/mfd/mfd-core.c')
-rw-r--r--drivers/mfd/mfd-core.c64
1 files changed, 60 insertions, 4 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);