i2c: move locking operations to their own struct

This makes it trivial to constify them, so do that.
Signed-off-by: Peter Rosin <peda@axentia.se>
Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>

drivers/gpu/drm/drm_dp_helper.c

@@ -790,6 +790,12 @@ static void unlock_bus(struct i2c_adapter *i2c, unsigned int flags)
 	mutex_unlock(&i2c_to_aux(i2c)->hw_mutex);
 }
 
+static const struct i2c_lock_operations drm_dp_i2c_lock_ops = {
+	.lock_bus = lock_bus,
+	.trylock_bus = trylock_bus,
+	.unlock_bus = unlock_bus,
+};
+
 /**
  * drm_dp_aux_init() - minimally initialise an aux channel
  * @aux: DisplayPort AUX channel
@@ -807,9 +813,7 @@ void drm_dp_aux_init(struct drm_dp_aux *aux)
 	aux->ddc.algo_data = aux;
 	aux->ddc.retries = 3;
 
-	aux->ddc.lock_bus = lock_bus;
-	aux->ddc.trylock_bus = trylock_bus;
-	aux->ddc.unlock_bus = unlock_bus;
+	aux->ddc.lock_ops = &drm_dp_i2c_lock_ops;
 }
 EXPORT_SYMBOL(drm_dp_aux_init);
 

drivers/i2c/i2c-core.c

@@ -1768,6 +1768,12 @@ static int __process_new_adapter(struct device_driver *d, void *data)
 	return i2c_do_add_adapter(to_i2c_driver(d), data);
 }
 
+static const struct i2c_lock_operations i2c_adapter_lock_ops = {
+	.lock_bus =    i2c_adapter_lock_bus,
+	.trylock_bus = i2c_adapter_trylock_bus,
+	.unlock_bus =  i2c_adapter_unlock_bus,
+};
+
 static int i2c_register_adapter(struct i2c_adapter *adap)
 {
 	int res = -EINVAL;
@@ -1787,11 +1793,8 @@ static int i2c_register_adapter(struct i2c_adapter *adap)
 		goto out_list;
 	}
 
-	if (!adap->lock_bus) {
-		adap->lock_bus = i2c_adapter_lock_bus;
-		adap->trylock_bus = i2c_adapter_trylock_bus;
-		adap->unlock_bus = i2c_adapter_unlock_bus;
-	}
+	if (!adap->lock_ops)
+		adap->lock_ops = &i2c_adapter_lock_ops;
 
 	rt_mutex_init(&adap->bus_lock);
 	rt_mutex_init(&adap->mux_lock);

drivers/i2c/i2c-mux.c

@@ -267,6 +267,18 @@ struct i2c_mux_core *i2c_mux_alloc(struct i2c_adapter *parent,
 }
 EXPORT_SYMBOL_GPL(i2c_mux_alloc);
 
+static const struct i2c_lock_operations i2c_mux_lock_ops = {
+	.lock_bus =    i2c_mux_lock_bus,
+	.trylock_bus = i2c_mux_trylock_bus,
+	.unlock_bus =  i2c_mux_unlock_bus,
+};
+
+static const struct i2c_lock_operations i2c_parent_lock_ops = {
+	.lock_bus =    i2c_parent_lock_bus,
+	.trylock_bus = i2c_parent_trylock_bus,
+	.unlock_bus =  i2c_parent_unlock_bus,
+};
+
 int i2c_mux_add_adapter(struct i2c_mux_core *muxc,
 			u32 force_nr, u32 chan_id,
 			unsigned int class)
@@ -316,15 +328,10 @@ int i2c_mux_add_adapter(struct i2c_mux_core *muxc,
 	priv->adap.retries = parent->retries;
 	priv->adap.timeout = parent->timeout;
 	priv->adap.quirks = parent->quirks;
-	if (muxc->mux_locked) {
-		priv->adap.lock_bus = i2c_mux_lock_bus;
-		priv->adap.trylock_bus = i2c_mux_trylock_bus;
-		priv->adap.unlock_bus = i2c_mux_unlock_bus;
-	} else {
-		priv->adap.lock_bus = i2c_parent_lock_bus;
-		priv->adap.trylock_bus = i2c_parent_trylock_bus;
-		priv->adap.unlock_bus = i2c_parent_unlock_bus;
-	}
+	if (muxc->mux_locked)
+		priv->adap.lock_ops = &i2c_mux_lock_ops;
+	else
+		priv->adap.lock_ops = &i2c_parent_lock_ops;
 
 	/* Sanity check on class */
 	if (i2c_mux_parent_classes(parent) & class)

include/linux/i2c.h

@@ -426,6 +426,20 @@ struct i2c_algorithm {
 #endif
 };
 
+/**
+ * struct i2c_lock_operations - represent I2C locking operations
+ * @lock_bus: Get exclusive access to an I2C bus segment
+ * @trylock_bus: Try to get exclusive access to an I2C bus segment
+ * @unlock_bus: Release exclusive access to an I2C bus segment
+ *
+ * The main operations are wrapped by i2c_lock_bus and i2c_unlock_bus.
+ */
+struct i2c_lock_operations {
+	void (*lock_bus)(struct i2c_adapter *, unsigned int flags);
+	int (*trylock_bus)(struct i2c_adapter *, unsigned int flags);
+	void (*unlock_bus)(struct i2c_adapter *, unsigned int flags);
+};
+
 /**
  * struct i2c_timings - I2C timing information
  * @bus_freq_hz: the bus frequency in Hz
@@ -536,6 +550,7 @@ struct i2c_adapter {
 	void *algo_data;
 
 	/* data fields that are valid for all devices	*/
+	const struct i2c_lock_operations *lock_ops;
 	struct rt_mutex bus_lock;
 	struct rt_mutex mux_lock;
 
@@ -552,10 +567,6 @@ struct i2c_adapter {
 
 	struct i2c_bus_recovery_info *bus_recovery_info;
 	const struct i2c_adapter_quirks *quirks;
-
-	void (*lock_bus)(struct i2c_adapter *, unsigned int flags);
-	int (*trylock_bus)(struct i2c_adapter *, unsigned int flags);
-	void (*unlock_bus)(struct i2c_adapter *, unsigned int flags);
 };
 #define to_i2c_adapter(d) container_of(d, struct i2c_adapter, dev)
 
@@ -597,7 +608,7 @@ int i2c_for_each_dev(void *data, int (*fn)(struct device *, void *));
 static inline void
 i2c_lock_bus(struct i2c_adapter *adapter, unsigned int flags)
 {
-	adapter->lock_bus(adapter, flags);
+	adapter->lock_ops->lock_bus(adapter, flags);
 }
 
 /**
@@ -611,7 +622,7 @@ i2c_lock_bus(struct i2c_adapter *adapter, unsigned int flags)
 static inline int
 i2c_trylock_bus(struct i2c_adapter *adapter, unsigned int flags)
 {
-	return adapter->trylock_bus(adapter, flags);
+	return adapter->lock_ops->trylock_bus(adapter, flags);
 }
 
 /**
@@ -623,7 +634,7 @@ i2c_trylock_bus(struct i2c_adapter *adapter, unsigned int flags)
 static inline void
 i2c_unlock_bus(struct i2c_adapter *adapter, unsigned int flags)
 {
-	adapter->unlock_bus(adapter, flags);
+	adapter->lock_ops->unlock_bus(adapter, flags);
 }
 
 static inline void