[PATCH v2 8/9] i2c: atr: add static flag

[Cosmin Tanislav <demonsingur@gmail.com>]

Some I2C ATRs do not support dynamic remapping, only static mapping
of direct children.

Add a new flag that prevents old mappings to be replaced or new mappings
to be created in the alias finding code paths.

Signed-off-by: Cosmin Tanislav <demonsingur@gmail.com>
---
 drivers/i2c/i2c-atr.c   | 16 ++++++++++++----
 include/linux/i2c-atr.h | 20 +++++++++++++++++---
 2 files changed, 29 insertions(+), 7 deletions(-)

diff --git a/drivers/i2c/i2c-atr.c b/drivers/i2c/i2c-atr.c
index d8748d71ae15..f7b853f55630 100644
--- a/drivers/i2c/i2c-atr.c
+++ b/drivers/i2c/i2c-atr.c
@@ -106,6 +106,7 @@ struct i2c_atr_chan {
  * @lock:      Lock for the I2C bus segment (see &struct i2c_lock_operations)
  * @lock_key:  Lock key for @lock
  * @max_adapters: Maximum number of adapters this I2C ATR can have
+ * @flags:     Flags for ATR
  * @alias_pool: Optional common pool of available client aliases
  * @i2c_nb:    Notifier for remote client add & del events
  * @adapter:   Array of adapters
@@ -122,6 +123,7 @@ struct i2c_atr {
 	struct mutex lock;
 	struct lock_class_key lock_key;
 	int max_adapters;
+	u32 flags;
 
 	struct i2c_atr_alias_pool *alias_pool;
 
@@ -339,12 +341,16 @@ i2c_atr_create_mapping_by_addr(struct i2c_atr_chan *chan, u16 addr)
 static struct i2c_atr_alias_pair *
 i2c_atr_get_mapping_by_addr(struct i2c_atr_chan *chan, u16 addr)
 {
+	struct i2c_atr *atr = chan->atr;
 	struct i2c_atr_alias_pair *c2a;
 
 	c2a = i2c_atr_find_mapping_by_addr(chan, addr);
 	if (c2a)
 		return c2a;
 
+	if (atr->flags & I2C_ATR_STATIC)
+		return NULL;
+
 	c2a = i2c_atr_create_mapping_by_addr(chan, addr);
 	if (c2a)
 		return c2a;
@@ -543,7 +549,7 @@ static int i2c_atr_attach_addr(struct i2c_adapter *adapter,
 	mutex_lock(&chan->alias_pairs_lock);
 
 	c2a = i2c_atr_create_mapping_by_addr(chan, addr);
-	if (!c2a)
+	if (!c2a && !(atr->flags & I2C_ATR_STATIC))
 		c2a = i2c_atr_replace_mapping_by_addr(chan, addr);
 
 	if (!c2a) {
@@ -702,8 +708,9 @@ static int i2c_atr_parse_alias_pool(struct i2c_atr *atr)
 	return ret;
 }
 
-struct i2c_atr *i2c_atr_new(struct i2c_adapter *parent, struct device *dev,
-			    const struct i2c_atr_ops *ops, int max_adapters)
+struct i2c_atr *i2c_atr_new_flags(struct i2c_adapter *parent, struct device *dev,
+				  const struct i2c_atr_ops *ops, int max_adapters,
+				  u32 flags)
 {
 	struct i2c_atr *atr;
 	int ret;
@@ -725,6 +732,7 @@ struct i2c_atr *i2c_atr_new(struct i2c_adapter *parent, struct device *dev,
 	atr->dev = dev;
 	atr->ops = ops;
 	atr->max_adapters = max_adapters;
+	atr->flags = flags;
 
 	if (parent->algo->master_xfer)
 		atr->algo.master_xfer = i2c_atr_master_xfer;
@@ -752,7 +760,7 @@ struct i2c_atr *i2c_atr_new(struct i2c_adapter *parent, struct device *dev,
 
 	return ERR_PTR(ret);
 }
-EXPORT_SYMBOL_NS_GPL(i2c_atr_new, "I2C_ATR");
+EXPORT_SYMBOL_NS_GPL(i2c_atr_new_flags, "I2C_ATR");
 
 void i2c_atr_delete(struct i2c_atr *atr)
 {
diff --git a/include/linux/i2c-atr.h b/include/linux/i2c-atr.h
index 1c3a5bcd939f..2f79d0d9140f 100644
--- a/include/linux/i2c-atr.h
+++ b/include/linux/i2c-atr.h
@@ -18,6 +18,15 @@ struct device;
 struct fwnode_handle;
 struct i2c_atr;
 
+/**
+ * enum i2c_atr_flags - Flags for an I2C ATR driver
+ *
+ * @I2C_ATR_STATIC: ATR does not support dynamic mapping, use static mapping
+ */
+enum i2c_atr_flags {
+	I2C_ATR_STATIC = BIT(0),
+};
+
 /**
  * struct i2c_atr_ops - Callbacks from ATR to the device driver.
  * @attach_addr: Notify the driver of a new device connected on a child
@@ -60,11 +69,12 @@ struct i2c_atr_adap_desc {
 };
 
 /**
- * i2c_atr_new() - Allocate and initialize an I2C ATR helper.
+ * i2c_atr_new_flags() - Allocate and initialize an I2C ATR helper.
  * @parent:       The parent (upstream) adapter
  * @dev:          The device acting as an ATR
  * @ops:          Driver-specific callbacks
  * @max_adapters: Maximum number of child adapters
+ * @flags:        Flags for ATR
  *
  * The new ATR helper is connected to the parent adapter but has no child
  * adapters. Call i2c_atr_add_adapter() to add some.
@@ -73,8 +83,12 @@ struct i2c_atr_adap_desc {
  *
  * Return: pointer to the new ATR helper object, or ERR_PTR
  */
-struct i2c_atr *i2c_atr_new(struct i2c_adapter *parent, struct device *dev,
-			    const struct i2c_atr_ops *ops, int max_adapters);
+struct i2c_atr *i2c_atr_new_flags(struct i2c_adapter *parent, struct device *dev,
+				  const struct i2c_atr_ops *ops, int max_adapters,
+				  u32 flags);
+
+#define i2c_atr_new(parent, dev, ops, max_adapters) \
+	i2c_atr_new_flags(parent, dev, ops, max_adapters, 0)
 
 /**
  * i2c_atr_delete - Delete an I2C ATR helper.
-- 
2.48.1