i2c: add suspended flag and accessors for i2c adapters

A few drivers open code the handling of suspended adapters. It could be
handled by the core, though, to ensure generic handling. This patch adds
the flag and accessor functions. The usage of these helpers is optional,
though. See the kerneldoc in this patch. Using the new flag, we now
reject further transfers if the adapter is already marked suspended.

Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>

1 files changed, 34 insertions, 0 deletions

diff --git a/include/linux/i2c.h b/include/linux/i2c.h
index 65b4eaed1d96..cba59d66c00d 100644
--- a/include/linux/i2c.h
+++ b/include/linux/i2c.h
@@ -680,6 +680,8 @@ struct i2c_adapter {
 	int timeout;			/* in jiffies */
 	int retries;
 	struct device dev;		/* the adapter device */
+	unsigned long locked_flags;	/* owned by the I2C core */
+#define I2C_ALF_IS_SUSPENDED	0
 
 	int nr;
 	char name[48];
@@ -762,6 +764,38 @@ i2c_unlock_bus(struct i2c_adapter *adapter, unsigned int flags)
 	adapter->lock_ops->unlock_bus(adapter, flags);
 }
 
+/**
+ * i2c_mark_adapter_suspended - Report suspended state of the adapter to the core
+ * @adap: Adapter to mark as suspended
+ *
+ * When using this helper to mark an adapter as suspended, the core will reject
+ * further transfers to this adapter. The usage of this helper is optional but
+ * recommended for devices having distinct handlers for system suspend and
+ * runtime suspend. More complex devices are free to implement custom solutions
+ * to reject transfers when suspended.
+ */
+static inline void i2c_mark_adapter_suspended(struct i2c_adapter *adap)
+{
+	i2c_lock_bus(adap, I2C_LOCK_ROOT_ADAPTER);
+	set_bit(I2C_ALF_IS_SUSPENDED, &adap->locked_flags);
+	i2c_unlock_bus(adap, I2C_LOCK_ROOT_ADAPTER);
+}
+
+/**
+ * i2c_mark_adapter_resumed - Report resumed state of the adapter to the core
+ * @adap: Adapter to mark as resumed
+ *
+ * When using this helper to mark an adapter as resumed, the core will allow
+ * further transfers to this adapter. See also further notes to
+ * @i2c_mark_adapter_suspended().
+ */
+static inline void i2c_mark_adapter_resumed(struct i2c_adapter *adap)
+{
+	i2c_lock_bus(adap, I2C_LOCK_ROOT_ADAPTER);
+	clear_bit(I2C_ALF_IS_SUSPENDED, &adap->locked_flags);
+	i2c_unlock_bus(adap, I2C_LOCK_ROOT_ADAPTER);
+}
+
 /*flags for the client struct: */
 #define I2C_CLIENT_PEC		0x04	/* Use Packet Error Checking */
 #define I2C_CLIENT_TEN		0x10	/* we have a ten bit chip address */