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[1/3] drivers: phy: Make NULL a valid phy reference

Message ID 1391264157-2112-1-git-send-email-andrew@lunn.ch
State Not Applicable
Delegated to: David Miller
Headers show

Commit Message

Andrew Lunn Feb. 1, 2014, 2:15 p.m. UTC 
The common clock framework considers NULL a valid clock
reference. This makes handling optional clocks simple, in that if the
optional clock is not available, a NULL reference can be used in the
place of a real clock, simplifying the clock consumer.

Extend this concept to the phy consumer API. A NULL can be passed to
the release calls, the phy_init() and phy_exit() calls, and
phy_power_on() and phy_power_off() and a NOP is performed.

Signed-off-by: Andrew Lunn <andrew@lunn.ch>
---
 Documentation/phy.txt  |  6 ++++++
 drivers/phy/phy-core.c | 18 ++++++++++++++++++
 2 files changed, 24 insertions(+)
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Patch

diff --git a/Documentation/phy.txt b/Documentation/phy.txt
index 0103e4b15b0e..2e24b993e95f 100644
--- a/Documentation/phy.txt
+++ b/Documentation/phy.txt
@@ -84,6 +84,12 @@  The only difference between the two APIs is that devm_phy_get associates the
 device with the PHY using devres on successful PHY get. On driver detach,
 release function is invoked on the the devres data and devres data is freed.
 
+It should be noted that NULL is a valid phy reference. All phy
+consumer calls on the NULL phy become NOPs. That is the release calls,
+the phy_init() and phy_exit() calls, and phy_power_on() and
+phy_power_off() calls are all NOP when applied to a NULL phy. The NULL
+phy is useful in devices for handling optional phy devices.
+
 5. Releasing a reference to the PHY
 
 When the controller no longer needs the PHY, it has to release the reference
diff --git a/drivers/phy/phy-core.c b/drivers/phy/phy-core.c
index 03cf8fb81554..74d34b5cc75c 100644
--- a/drivers/phy/phy-core.c
+++ b/drivers/phy/phy-core.c
@@ -150,6 +150,9 @@  int phy_init(struct phy *phy)
 {
 	int ret;
 
+	if (!phy)
+		return 0;
+
 	ret = phy_pm_runtime_get_sync(phy);
 	if (ret < 0 && ret != -ENOTSUPP)
 		return ret;
@@ -174,6 +177,9 @@  int phy_exit(struct phy *phy)
 {
 	int ret;
 
+	if (!phy)
+		return 0;
+
 	ret = phy_pm_runtime_get_sync(phy);
 	if (ret < 0 && ret != -ENOTSUPP)
 		return ret;
@@ -198,6 +204,9 @@  int phy_power_on(struct phy *phy)
 {
 	int ret = -ENOTSUPP;
 
+	if (!phy)
+		return 0;
+
 	ret = phy_pm_runtime_get_sync(phy);
 	if (ret < 0 && ret != -ENOTSUPP)
 		return ret;
@@ -222,6 +231,9 @@  int phy_power_off(struct phy *phy)
 {
 	int ret = -ENOTSUPP;
 
+	if (!phy)
+		return 0;
+
 	mutex_lock(&phy->mutex);
 	if (--phy->power_count == 0 && phy->ops->power_off) {
 		ret =  phy->ops->power_off(phy);
@@ -290,6 +302,9 @@  err0:
  */
 void phy_put(struct phy *phy)
 {
+	if (!phy)
+		return;
+
 	if (IS_ERR(phy))
 		return;
 
@@ -310,6 +325,9 @@  void devm_phy_put(struct device *dev, struct phy *phy)
 {
 	int r;
 
+	if (!phy)
+		return;
+
 	r = devres_destroy(dev, devm_phy_release, devm_phy_match, phy);
 	dev_WARN_ONCE(dev, r, "couldn't find PHY resource\n");
 }