i2c: bcm2835: Store pointer to bus clock

The commit bebff81fb8b9 ("i2c: bcm2835: Model Divider in CCF") introduced
a NULL pointer dereference on driver unload. It seems that we can't fetch
the bus clock via devm_clk_get in bcm2835_i2c_remove. As an alternative
approach store a pointer to the bus clock in the private driver structure.

Fixes: bebff81fb8b9 ("i2c: bcm2835: Model Divider in CCF")
Signed-off-by: Stefan Wahren <[e-mail]>
Signed-off-by: Wolfram Sang <[e-mail]>

drivers/i2c/busses/i2c-bcm2835.c

···
 	struct i2c_adapter adapter;
 	struct completion completion;
 	struct i2c_msg *curr_msg;
+	struct clk *bus_clk;
 	int num_msgs;
 	u32 msg_err;
 	u8 *msg_buf;
···
 	struct resource *mem, *irq;
 	int ret;
 	struct i2c_adapter *adap;
-	struct clk *bus_clk;
 	struct clk *mclk;
 	u32 bus_clk_rate;
 
···
 		return PTR_ERR(mclk);
 	}
 
-	bus_clk = bcm2835_i2c_register_div(&pdev->dev, mclk, i2c_dev);
+	i2c_dev->bus_clk = bcm2835_i2c_register_div(&pdev->dev, mclk, i2c_dev);
 
-	if (IS_ERR(bus_clk)) {
+	if (IS_ERR(i2c_dev->bus_clk)) {
 		dev_err(&pdev->dev, "Could not register clock\n");
-		return PTR_ERR(bus_clk);
+		return PTR_ERR(i2c_dev->bus_clk);
 	}
 
 	ret = of_property_read_u32(pdev->dev.of_node, "clock-frequency",
···
 		bus_clk_rate = 100000;
 	}
 
-	ret = clk_set_rate_exclusive(bus_clk, bus_clk_rate);
+	ret = clk_set_rate_exclusive(i2c_dev->bus_clk, bus_clk_rate);
 	if (ret < 0) {
 		dev_err(&pdev->dev, "Could not set clock frequency\n");
 		return ret;
 	}
 
-	ret = clk_prepare_enable(bus_clk);
+	ret = clk_prepare_enable(i2c_dev->bus_clk);
 	if (ret) {
 		dev_err(&pdev->dev, "Couldn't prepare clock");
 		return ret;
···
 static int bcm2835_i2c_remove(struct platform_device *pdev)
 {
 	struct bcm2835_i2c_dev *i2c_dev = platform_get_drvdata(pdev);
-	struct clk *bus_clk = devm_clk_get(i2c_dev->dev, "div");
 
-	clk_rate_exclusive_put(bus_clk);
-	clk_disable_unprepare(bus_clk);
+	clk_rate_exclusive_put(i2c_dev->bus_clk);
+	clk_disable_unprepare(i2c_dev->bus_clk);
 
 	free_irq(i2c_dev->irq, i2c_dev);
 	i2c_del_adapter(&i2c_dev->adapter);