V4L/DVB (7134): tuner: create a macro for sharing state between hybrid tuner instances

Create a macro implementing a standard method to share state amongst
multiple instances of a hybrid tuner object.

Also, prepare tuner_foo printk macros for the removal of PREFIX
Signed-off-by: Michael Krufky <mkrufky@linuxtv.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>

drivers/media/video/tuner-i2c.h

@@ -26,6 +26,10 @@
 struct tuner_i2c_props {
 	u8 addr;
 	struct i2c_adapter *adap;
+
+	/* used for tuner instance management */
+	int count;
+	char *name;
 };
 
 static inline int tuner_i2c_xfer_send(struct tuner_i2c_props *props, char *buf, int len)
@@ -59,29 +63,105 @@ static inline int tuner_i2c_xfer_send_recv(struct tuner_i2c_props *props,
 	return (ret == 2) ? ilen : ret;
 }
 
-#define tuner_warn(fmt, arg...) do {					\
-	printk(KERN_WARNING "%s %d-%04x: " fmt, PREFIX,			\
-			i2c_adapter_id(priv->i2c_props.adap),		\
-			priv->i2c_props.addr, ##arg);			\
+/* Callers must declare as a global for the module:
+ *
+ * static LIST_HEAD(hybrid_tuner_instance_list);
+ *
+ * hybrid_tuner_instance_list should be the third argument
+ * passed into hybrid_tuner_request_state().
+ *
+ * state structure must contain the following:
+ *
+ * 	struct list_head	hybrid_tuner_instance_list;
+ *	struct tuner_i2c_props	i2c_props;
+ *
+ * hybrid_tuner_instance_list (both within state structure and globally)
+ * is only required if the driver is using hybrid_tuner_request_state
+ * and hybrid_tuner_release_state to manage state sharing between
+ * multiple instances of hybrid tuners.
+ */
+
+#define tuner_printk(kernlvl, i2cprops, fmt, arg...) do {		\
+	printk(kernlvl "%s %d-%04x: " fmt, i2cprops.name,		\
+			i2c_adapter_id(i2cprops.adap),			\
+			i2cprops.addr, ##arg);				\
 	 } while (0)
 
-#define tuner_info(fmt, arg...) do {					\
-	printk(KERN_INFO "%s %d-%04x: " fmt, PREFIX,			\
-			i2c_adapter_id(priv->i2c_props.adap),		\
-			priv->i2c_props.addr , ##arg);			\
+/* TO DO: convert all callers of these macros to pass in
+ * struct tuner_i2c_props, then remove the macro wrappers */
+
+#define __tuner_warn(i2cprops, fmt, arg...) do {			\
+	tuner_printk(KERN_WARNING, i2cprops, fmt, ##arg);		\
 	} while (0)
 
-#define tuner_err(fmt, arg...) do {					\
-	printk(KERN_ERR "%s %d-%04x: " fmt, PREFIX, 			\
-			i2c_adapter_id(priv->i2c_props.adap),		\
-			priv->i2c_props.addr , ##arg);			\
+#define __tuner_info(i2cprops, fmt, arg...) do {			\
+	tuner_printk(KERN_INFO, i2cprops, fmt, ##arg);			\
 	} while (0)
 
-#define tuner_dbg(fmt, arg...) do {					\
+#define __tuner_err(i2cprops, fmt, arg...) do {				\
+	tuner_printk(KERN_ERR, i2cprops, fmt, ##arg);			\
+	} while (0)
+
+#define __tuner_dbg(i2cprops, fmt, arg...) do {				\
 	if ((debug))							\
-		printk(KERN_DEBUG "%s %d-%04x: " fmt, PREFIX,		\
-			i2c_adapter_id(priv->i2c_props.adap),		\
-			priv->i2c_props.addr , ##arg);			\
+		tuner_printk(KERN_DEBUG, i2cprops, fmt, ##arg);		\
 	} while (0)
 
+#define tuner_warn(fmt, arg...) __tuner_warn(priv->i2c_props, fmt, ##arg)
+#define tuner_info(fmt, arg...) __tuner_info(priv->i2c_props, fmt, ##arg)
+#define tuner_err(fmt, arg...) __tuner_err(priv->i2c_props, fmt, ##arg)
+#define tuner_dbg(fmt, arg...) __tuner_dbg(priv->i2c_props, fmt, ##arg)
+
+/****************************************************************************/
+
+/* The return value of hybrid_tuner_request_state indicates the number of
+ * instances using this tuner object.
+ *
+ * 0 - no instances, indicates an error - kzalloc must have failed
+ *
+ * 1 - one instance, indicates that the tuner object was created successfully
+ *
+ * 2 (or more) instances, indicates that an existing tuner object was found
+ */
+
+#define hybrid_tuner_request_state(type, state, list, i2cadap, i2caddr, devname)\
+({									\
+	int __ret = 0;							\
+	list_for_each_entry(state, &list, hybrid_tuner_instance_list) {	\
+		if ((i2c_adapter_id(state->i2c_props.adap) ==		\
+		     i2c_adapter_id(i2cadap)) &&			\
+		    (state->i2c_props.addr == i2caddr)) {		\
+			__tuner_info(state->i2c_props,			\
+				     "attaching existing instance\n");	\
+			state->i2c_props.count++;			\
+			__ret = state->i2c_props.count;			\
+			break;						\
+		}							\
+	}								\
+	if (0 == __ret) {						\
+		state = kzalloc(sizeof(type), GFP_KERNEL);		\
+		if (NULL == state)					\
+			goto __fail;					\
+		state->i2c_props.addr = i2caddr;			\
+		state->i2c_props.adap = i2cadap;			\
+		state->i2c_props.name = devname;			\
+		__tuner_info(state->i2c_props,				\
+			     "creating new instance\n");		\
+		list_add_tail(&state->hybrid_tuner_instance_list, &list);\
+		state->i2c_props.count++;				\
+		__ret = state->i2c_props.count;				\
+	}								\
+__fail:									\
+	__ret;								\
+})
+
+#define hybrid_tuner_release_state(state) do {				\
+	state->i2c_props.count--;					\
+	if (!state->i2c_props.count) {					\
+		__tuner_info(state->i2c_props, "destroying instance\n");\
+		list_del(&state->hybrid_tuner_instance_list);		\
+		kfree(state);						\
+	}								\
+} while (0)
+
 #endif /* __TUNER_I2C_H__ */