[PATCH v4 09/10] mfd: mfd-core: Remove usage counting for .{en, dis}able() call-backs

Lee Jones
2019-11-01T07:47:58Z

The MFD implementation for reference counting was complex and unnecessary.
There was only one bona fide user which has now been converted to handle
the process in a different way. Any future resource protection, shared
enablement functions should be handed by the parent device, rather than
through the MFD subsystem API.

Signed-off-by: Lee Jones <lee.jones@linaro.org>
Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org>
Reviewed-by: Mark Brown <broonie@kernel.org>
---
drivers/mfd/mfd-core.c | 57 +++++++---------------------------------
include/linux/mfd/core.h | 2 --
2 files changed, 9 insertions(+), 50 deletions(-)

diff --git a/drivers/mfd/mfd-core.c b/drivers/mfd/mfd-core.c
index e38e411ca775..2535dd3605c0 100644
--- a/drivers/mfd/mfd-core.c
+++ b/drivers/mfd/mfd-core.c
@@ -26,53 +26,31 @@ static struct device_type mfd_dev_type = {
int mfd_cell_enable(struct platform_device *pdev)
{
const struct mfd_cell *cell = mfd_get_cell(pdev);
- int err = 0;

if (!cell->enable) {
dev_dbg(&pdev->dev, "No .enable() call-back registered\n");
return 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;
+ return cell->enable(pdev);
}
EXPORT_SYMBOL(mfd_cell_enable);

int mfd_cell_disable(struct platform_device *pdev)
{
const struct mfd_cell *cell = mfd_get_cell(pdev);
- int err = 0;

if (!cell->disable) {
dev_dbg(&pdev->dev, "No .disable() call-back registered\n");
return 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;
+ return cell->disable(pdev);
}
EXPORT_SYMBOL(mfd_cell_disable);

static int mfd_platform_add_cell(struct platform_device *pdev,
- const struct mfd_cell *cell,
- atomic_t *usage_count)
+ const struct mfd_cell *cell)
{
if (!cell)
return 0;
@@ -81,7 +59,6 @@ static int mfd_platform_add_cell(struct platform_device *pdev,
if (!pdev->mfd_cell)
return -ENOMEM;

- pdev->mfd_cell->usage_count = usage_count;
return 0;
}

@@ -144,7 +121,7 @@ static inline void mfd_acpi_add_device(const struct mfd_cell *cell,
#endif

static int mfd_add_device(struct device *parent, int id,
- const struct mfd_cell *cell, atomic_t *usage_count,
+ const struct mfd_cell *cell,
struct resource *mem_base,
int irq_base, struct irq_domain *domain)
{
@@ -206,7 +183,7 @@ static int mfd_add_device(struct device *parent, int id,
goto fail_alias;
}

- ret = mfd_platform_add_cell(pdev, cell, usage_count);
+ ret = mfd_platform_add_cell(pdev, cell);
if (ret)
goto fail_alias;

@@ -296,16 +273,9 @@ int mfd_add_devices(struct device *parent, int id,
{
int i;
int ret;
- atomic_t *cnts;
-
- /* initialize reference counting for all cells */
- cnts = kcalloc(n_devs, sizeof(*cnts), GFP_KERNEL);
- if (!cnts)
- return -ENOMEM;

for (i = 0; i < n_devs; i++) {
- atomic_set(&cnts[i], 0);
- ret = mfd_add_device(parent, id, cells + i, cnts + i, mem_base,
+ ret = mfd_add_device(parent, id, cells + i, mem_base,
irq_base, domain);
if (ret)
goto fail;
@@ -316,17 +286,15 @@ int mfd_add_devices(struct device *parent, int id,
fail:
if (i)
mfd_remove_devices(parent);
- else
- kfree(cnts);
+
return ret;
}
EXPORT_SYMBOL(mfd_add_devices);

-static int mfd_remove_devices_fn(struct device *dev, void *c)
+static int mfd_remove_devices_fn(struct device *dev, void *data)
{
struct platform_device *pdev;
const struct mfd_cell *cell;
- atomic_t **usage_count = c;

if (dev->type != &mfd_dev_type)
return 0;
@@ -337,20 +305,13 @@ static int mfd_remove_devices_fn(struct device *dev, void *c)
regulator_bulk_unregister_supply_alias(dev, cell->parent_supplies,
cell->num_parent_supplies);

- /* 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)
{
- atomic_t *cnts = NULL;
-
- device_for_each_child_reverse(parent, &cnts, mfd_remove_devices_fn);
- kfree(cnts);
+ device_for_each_child_reverse(parent, NULL, mfd_remove_devices_fn);
}
EXPORT_SYMBOL(mfd_remove_devices);

diff --git a/include/linux/mfd/core.h b/include/linux/mfd/core.h
index bd8c0e089164..919f09fb07b7 100644
--- a/include/linux/mfd/core.h
+++ b/include/linux/mfd/core.h
@@ -30,8 +30,6 @@ 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);