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Subject[PATCH 1/2] mux: add mux_control_get_optional() API
Date
From: Stephen Boyd <stephen.boyd@linaro.org>

Sometimes drivers only use muxes under certain scenarios. For
example, the chipidea usb controller may be connected to a usb
switch on some platforms, and connected directly to a usb port on
others. The driver won't know one way or the other though, so add
a mux_control_get_optional() API that allows the driver to
differentiate errors getting the mux from there not being a mux
for the driver to use at all.
---
Documentation/driver-model/devres.txt | 1 +
drivers/mux/core.c | 104 +++++++++++++++++++++++++++-------
include/linux/mux/consumer.h | 4 ++
3 files changed, 89 insertions(+), 20 deletions(-)

I haven't tested this patch, and hence I have not signed it and I also
removed the sign-off from Stephen...

Cheers,
peda

diff --git a/Documentation/driver-model/devres.txt b/Documentation/driver-model/devres.txt
index 30e04f7a690d..4fdd3e63ff8b 100644
--- a/Documentation/driver-model/devres.txt
+++ b/Documentation/driver-model/devres.txt
@@ -342,6 +342,7 @@ MUX
devm_mux_chip_alloc()
devm_mux_chip_register()
devm_mux_control_get()
+ devm_mux_control_get_optional()

PER-CPU MEM
devm_alloc_percpu()
diff --git a/drivers/mux/core.c b/drivers/mux/core.c
index 2260063b0ea8..2eb234300669 100644
--- a/drivers/mux/core.c
+++ b/drivers/mux/core.c
@@ -289,6 +289,9 @@ EXPORT_SYMBOL_GPL(devm_mux_chip_register);
*/
unsigned int mux_control_states(struct mux_control *mux)
{
+ if (!mux)
+ return 0;
+
return mux->states;
}
EXPORT_SYMBOL_GPL(mux_control_states);
@@ -338,6 +341,9 @@ int mux_control_select(struct mux_control *mux, unsigned int state)
{
int ret;

+ if (!mux)
+ return 0;
+
ret = down_killable(&mux->lock);
if (ret < 0)
return ret;
@@ -370,6 +376,9 @@ int mux_control_try_select(struct mux_control *mux, unsigned int state)
{
int ret;

+ if (!mux)
+ return 0;
+
if (down_trylock(&mux->lock))
return -EBUSY;

@@ -398,6 +407,9 @@ int mux_control_deselect(struct mux_control *mux)
{
int ret = 0;

+ if (!mux)
+ return 0;
+
if (mux->idle_state != MUX_IDLE_AS_IS &&
mux->idle_state != mux->cached_state)
ret = mux_control_set(mux, mux->idle_state);
@@ -422,14 +434,8 @@ static struct mux_chip *of_find_mux_chip_by_node(struct device_node *np)
return dev ? to_mux_chip(dev) : NULL;
}

-/**
- * mux_control_get() - Get the mux-control for a device.
- * @dev: The device that needs a mux-control.
- * @mux_name: The name identifying the mux-control.
- *
- * Return: A pointer to the mux-control, or an ERR_PTR with a negative errno.
- */
-struct mux_control *mux_control_get(struct device *dev, const char *mux_name)
+static struct mux_control *
+__mux_control_get(struct device *dev, const char *mux_name, bool optional)
{
struct device_node *np = dev->of_node;
struct of_phandle_args args;
@@ -441,16 +447,22 @@ struct mux_control *mux_control_get(struct device *dev, const char *mux_name)
if (mux_name) {
index = of_property_match_string(np, "mux-control-names",
mux_name);
+ if ((index == -EINVAL || index == -ENODATA) && optional)
+ return NULL;
if (index < 0) {
dev_err(dev, "mux controller '%s' not found\n",
mux_name);
return ERR_PTR(index);
}
+ /* OF does point to a mux, so it's no longer optional */
+ optional = false;
}

ret = of_parse_phandle_with_args(np,
"mux-controls", "#mux-control-cells",
index, &args);
+ if (ret == -ENOENT && optional)
+ return NULL;
if (ret) {
dev_err(dev, "%pOF: failed to get mux-control %s(%i)\n",
np, mux_name ?: "", index);
@@ -482,9 +494,36 @@ struct mux_control *mux_control_get(struct device *dev, const char *mux_name)
get_device(&mux_chip->dev);
return &mux_chip->mux[controller];
}
+
+/**
+ * mux_control_get() - Get the mux-control for a device.
+ * @dev: The device that needs a mux-control.
+ * @mux_name: The name identifying the mux-control.
+ *
+ * Return: A pointer to the mux-control, or an ERR_PTR with a negative errno.
+ */
+struct mux_control *mux_control_get(struct device *dev, const char *mux_name)
+{
+ return __mux_control_get(dev, mux_name, false);
+}
EXPORT_SYMBOL_GPL(mux_control_get);

/**
+ * mux_control_get_optional() - Get the optional mux-control for a device.
+ * @dev: The device that needs a mux-control.
+ * @mux_name: The name identifying the mux-control.
+ *
+ * Return: NULL if no mux with the provided name is found, a pointer to
+ * the named mux-control or an ERR_PTR with a negative errno.
+ */
+struct mux_control *
+mux_control_get_optional(struct device *dev, const char *mux_name)
+{
+ return __mux_control_get(dev, mux_name, true);
+}
+EXPORT_SYMBOL_GPL(mux_control_get_optional);
+
+/**
* mux_control_put() - Put away the mux-control for good.
* @mux: The mux-control to put away.
*
@@ -492,6 +531,9 @@ EXPORT_SYMBOL_GPL(mux_control_get);
*/
void mux_control_put(struct mux_control *mux)
{
+ if (!mux)
+ return;
+
put_device(&mux->chip->dev);
}
EXPORT_SYMBOL_GPL(mux_control_put);
@@ -503,16 +545,8 @@ static void devm_mux_control_release(struct device *dev, void *res)
mux_control_put(mux);
}

-/**
- * devm_mux_control_get() - Get the mux-control for a device, with resource
- * management.
- * @dev: The device that needs a mux-control.
- * @mux_name: The name identifying the mux-control.
- *
- * Return: Pointer to the mux-control, or an ERR_PTR with a negative errno.
- */
-struct mux_control *devm_mux_control_get(struct device *dev,
- const char *mux_name)
+static struct mux_control *
+__devm_mux_control_get(struct device *dev, const char *mux_name, bool optional)
{
struct mux_control **ptr, *mux;

@@ -520,8 +554,8 @@ struct mux_control *devm_mux_control_get(struct device *dev,
if (!ptr)
return ERR_PTR(-ENOMEM);

- mux = mux_control_get(dev, mux_name);
- if (IS_ERR(mux)) {
+ mux = __mux_control_get(dev, mux_name, optional);
+ if (IS_ERR_OR_NULL(mux)) {
devres_free(ptr);
return mux;
}
@@ -531,8 +565,38 @@ struct mux_control *devm_mux_control_get(struct device *dev,

return mux;
}
+
+/**
+ * devm_mux_control_get() - Get the mux-control for a device, with resource
+ * management.
+ * @dev: The device that needs a mux-control.
+ * @mux_name: The name identifying the mux-control.
+ *
+ * Return: Pointer to the mux-control, or an ERR_PTR with a negative errno.
+ */
+struct mux_control *
+devm_mux_control_get(struct device *dev, const char *mux_name)
+{
+ return __devm_mux_control_get(dev, mux_name, false);
+}
EXPORT_SYMBOL_GPL(devm_mux_control_get);

+/**
+ * devm_mux_control_get_optional() - Get the optional mux-control for a device,
+ * with resource management.
+ * @dev: The device that needs a mux-control.
+ * @mux_name: The name identifying the mux-control.
+ *
+ * Return: NULL if no mux with the provided name is found, a pointer to
+ * the named mux-control or an ERR_PTR with a negative errno.
+ */
+struct mux_control *
+devm_mux_control_get_optional(struct device *dev, const char *mux_name)
+{
+ return __devm_mux_control_get(dev, mux_name, true);
+}
+EXPORT_SYMBOL_GPL(devm_mux_control_get_optional);
+
/*
* Using subsys_initcall instead of module_init here to try to ensure - for
* the non-modular case - that the subsystem is initialized when mux consumers
diff --git a/include/linux/mux/consumer.h b/include/linux/mux/consumer.h
index ea96d4c82be7..fc98547bf494 100644
--- a/include/linux/mux/consumer.h
+++ b/include/linux/mux/consumer.h
@@ -26,9 +26,13 @@ int __must_check mux_control_try_select(struct mux_control *mux,
int mux_control_deselect(struct mux_control *mux);

struct mux_control *mux_control_get(struct device *dev, const char *mux_name);
+struct mux_control *mux_control_get_optional(struct device *dev,
+ const char *mux_name);
void mux_control_put(struct mux_control *mux);

struct mux_control *devm_mux_control_get(struct device *dev,
const char *mux_name);
+struct mux_control *devm_mux_control_get_optional(struct device *dev,
+ const char *mux_name);

#endif /* _LINUX_MUX_CONSUMER_H */
--
2.11.0
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