[sw][driver][i2c] make i2c-ocores work with kernels 4.7 and newer

Signed-off-by: Dimitris Lampridis <dimitris.lampridis@cern.ch>

software/i2c-ocores/drivers/i2c/busses/i2c-ocores.c

@@ -41,8 +41,12 @@ struct ocores_i2c {
 	unsigned long flags;
 	wait_queue_head_t wait;
 	struct i2c_adapter adap;
+#if  KERNEL_VERSION(4, 7, 0) <= LINUX_VERSION_CODE
+        struct i2c_mux_core *adap_mux;
+#else
 	struct i2c_adapter **adap_mux;
 	unsigned int n_adap_mux;
+#endif
 	struct i2c_msg *msg;
 	int pos;
 	int nmsgs;
@@ -582,10 +586,17 @@ MODULE_DEVICE_TABLE(id_table, ocores_id_table);
 /**
  * It selects the I2C bus to use and lock it
  */
+#if  KERNEL_VERSION(4, 7, 0) <= LINUX_VERSION_CODE
+static int ocores_i2c_mux_select(struct i2c_mux_core *adap_mux,
+				 u32 num)
+{
+	struct ocores_i2c *i2c = adap_mux->priv;
+#else
 static int ocores_i2c_mux_select(struct i2c_adapter *adap,
 				 void *priv, u32 num)
 {
 	struct ocores_i2c *i2c = priv;
+#endif
 	u8 mux;
 
 	mux = oc_getreg(i2c, OCI2C_OHWR_MUX);
@@ -605,16 +616,25 @@ static int ocores_i2c_mux_select(struct i2c_adapter *adap,
 /**
  * It unlocks the bus so that it can be changed.
  */
+#if  KERNEL_VERSION(4, 7, 0) <= LINUX_VERSION_CODE
+static int ocores_i2c_mux_deselect(struct i2c_mux_core *adap_mux,
+				   u32 num)
+{
+	struct ocores_i2c *i2c = adap_mux->priv;
+        struct device *dev = adap_mux->dev;
+#else
 static int ocores_i2c_mux_deselect(struct i2c_adapter *adap,
 				   void *priv, u32 num)
 {
 	struct ocores_i2c *i2c = priv;
+        struct device *dev = &adap->dev;
+#endif
 	u8 mux;
 
 	/* Unlock bus selection */
 	mux = oc_getreg(i2c, OCI2C_OHWR_MUX);
 	if (unlikely(!(mux & OCI2C_OHWR_MUX_BUSY)))
-		dev_err(&adap->dev, "deselect a bus that was not selected\n");
+		dev_err(dev, "deselect a bus that was not selected\n");
 	mux &= ~OCI2C_OHWR_MUX_BUSY;
 	oc_setreg(i2c, OCI2C_OHWR_MUX, mux);
 
@@ -627,12 +647,40 @@ static int ocores_i2c_mux_deselect(struct i2c_adapter *adap,
  */
 static int ocores_i2c_probe_ohwr(struct ocores_i2c *i2c)
 {
-	int err, i;
+	int i, err = 0;
+
+#if  KERNEL_VERSION(4, 7, 0) <= LINUX_VERSION_CODE
+	i2c->adap_mux = i2c_mux_alloc(&i2c->adap, i2c->adap.dev.parent,
+				      2, sizeof(i2c), 0,
+				      ocores_i2c_mux_select,
+				      ocores_i2c_mux_deselect);
+	if (!i2c->adap_mux) {
+		err = -ENOMEM;
+		goto err_exit;
+	}
+	i2c->adap_mux->priv = i2c;
+	for (i = 0; i < i2c->adap_mux->max_adapters; ++i) {
+		err = i2c_mux_add_adapter(i2c->adap_mux,
+					  0, i, 0);
+		if (err)
+			goto err_add;
+	}
+
+	return 0;
 
+err_add:
+	i2c_mux_del_adapters(i2c->adap_mux);
+err_exit:
+	return err;
+#else /* KERNEL < 4.7 */
 	i2c->n_adap_mux = 2;
 	i2c->adap_mux = devm_kzalloc(&i2c->adap.dev,
 				     sizeof(void *) * i2c->n_adap_mux,
 				     GFP_KERNEL);
+	if (!i2c->adap_mux) {
+		err =  -ENOMEM;
+		goto err_exit;
+	}
 	for (i = 0; i < i2c->n_adap_mux; ++i) {
 		i2c->adap_mux[i] = i2c_add_mux_adapter(&i2c->adap,
 						       i2c->adap.dev.parent,
@@ -652,7 +700,9 @@ static int ocores_i2c_probe_ohwr(struct ocores_i2c *i2c)
 err_add:
 	while (--i >= 0)
 		i2c_del_mux_adapter(i2c->adap_mux[i]);
+err_exit:
 	return err;
+#endif
 }
 
 /**
@@ -660,10 +710,14 @@ err_add:
  */
 static void ocores_i2c_remove_ohwr(struct ocores_i2c *i2c)
 {
+#if  KERNEL_VERSION(4, 7, 0) <= LINUX_VERSION_CODE
+	i2c_mux_del_adapters(i2c->adap_mux);
+#else
 	int i;
 
 	for (i = 0; i < i2c->n_adap_mux; ++i)
 		i2c_del_mux_adapter(i2c->adap_mux[i]);
+#endif
 }
 
 #ifdef CONFIG_OF