can: rcar_can: support all input clocks

When writing the driver, I didn't give enough attention to the possible sources
of the CAN clock: although the value of the CLKR register was specified by the
platform data, the driver only handled one case, that is CAN clock being
sourced from the clkp1 clock, the same that clocks the whole CAN module. In
order to fix that overlook, we'll have to handle the CAN clock separately from
the peripheral clock (however, clkp1 will be specified for a CAN device only
once)...

Signed-off-by: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

drivers/net/can/rcar_can.c

@@ -87,6 +87,7 @@ struct rcar_can_priv {
 	struct napi_struct napi;
 	struct rcar_can_regs __iomem *regs;
 	struct clk *clk;
+	struct clk *can_clk;
 	u8 tx_dlc[RCAR_CAN_FIFO_DEPTH];
 	u32 tx_head;
 	u32 tx_tail;
@@ -505,14 +506,20 @@ static int rcar_can_open(struct net_device *ndev)
 
 	err = clk_prepare_enable(priv->clk);
 	if (err) {
-		netdev_err(ndev, "clk_prepare_enable() failed, error %d\n",
+		netdev_err(ndev, "failed to enable periperal clock, error %d\n",
 			   err);
 		goto out;
 	}
+	err = clk_prepare_enable(priv->can_clk);
+	if (err) {
+		netdev_err(ndev, "failed to enable CAN clock, error %d\n",
+			   err);
+		goto out_clock;
+	}
 	err = open_candev(ndev);
 	if (err) {
 		netdev_err(ndev, "open_candev() failed, error %d\n", err);
-		goto out_clock;
+		goto out_can_clock;
 	}
 	napi_enable(&priv->napi);
 	err = request_irq(ndev->irq, rcar_can_interrupt, 0, ndev->name, ndev);
@@ -527,6 +534,8 @@ static int rcar_can_open(struct net_device *ndev)
 out_close:
 	napi_disable(&priv->napi);
 	close_candev(ndev);
+out_can_clock:
+	clk_disable_unprepare(priv->can_clk);
 out_clock:
 	clk_disable_unprepare(priv->clk);
 out:
@@ -565,6 +574,7 @@ static int rcar_can_close(struct net_device *ndev)
 	rcar_can_stop(ndev);
 	free_irq(ndev->irq, ndev);
 	napi_disable(&priv->napi);
+	clk_disable_unprepare(priv->can_clk);
 	clk_disable_unprepare(priv->clk);
 	close_candev(ndev);
 	can_led_event(ndev, CAN_LED_EVENT_STOP);
@@ -715,6 +725,12 @@ static int rcar_can_get_berr_counter(const struct net_device *dev,
 	return 0;
 }
 
+static const char * const clock_names[] = {
+	[CLKR_CLKP1]	= "clkp1",
+	[CLKR_CLKP2]	= "clkp2",
+	[CLKR_CLKEXT]	= "can_clk",
+};
+
 static int rcar_can_probe(struct platform_device *pdev)
 {
 	struct rcar_can_platform_data *pdata;
@@ -722,6 +738,7 @@ static int rcar_can_probe(struct platform_device *pdev)
 	struct net_device *ndev;
 	struct resource *mem;
 	void __iomem *addr;
+	u32 clock_select;
 	int err = -ENODEV;
 	int irq;
 
@@ -730,6 +747,7 @@ static int rcar_can_probe(struct platform_device *pdev)
 		dev_err(&pdev->dev, "No platform data provided!\n");
 		goto fail;
 	}
+	clock_select = pdata->clock_select;
 
 	irq = platform_get_irq(pdev, 0);
 	if (!irq) {
@@ -753,10 +771,22 @@ static int rcar_can_probe(struct platform_device *pdev)
 
 	priv = netdev_priv(ndev);
 
-	priv->clk = devm_clk_get(&pdev->dev, NULL);
+	priv->clk = devm_clk_get(&pdev->dev, "clkp1");
 	if (IS_ERR(priv->clk)) {
 		err = PTR_ERR(priv->clk);
-		dev_err(&pdev->dev, "cannot get clock: %d\n", err);
+		dev_err(&pdev->dev, "cannot get peripheral clock: %d\n", err);
+		goto fail_clk;
+	}
+
+	if (clock_select >= ARRAY_SIZE(clock_names)) {
+		err = -EINVAL;
+		dev_err(&pdev->dev, "invalid CAN clock selected\n");
+		goto fail_clk;
+	}
+	priv->can_clk = devm_clk_get(&pdev->dev, clock_names[clock_select]);
+	if (IS_ERR(priv->can_clk)) {
+		err = PTR_ERR(priv->can_clk);
+		dev_err(&pdev->dev, "cannot get CAN clock: %d\n", err);
 		goto fail_clk;
 	}
 
@@ -765,8 +795,8 @@ static int rcar_can_probe(struct platform_device *pdev)
 	ndev->flags |= IFF_ECHO;
 	priv->ndev = ndev;
 	priv->regs = addr;
-	priv->clock_select = pdata->clock_select;
-	priv->can.clock.freq = clk_get_rate(priv->clk);
+	priv->clock_select = clock_select;
+	priv->can.clock.freq = clk_get_rate(priv->can_clk);
 	priv->can.bittiming_const = &rcar_can_bittiming_const;
 	priv->can.do_set_mode = rcar_can_do_set_mode;
 	priv->can.do_get_berr_counter = rcar_can_get_berr_counter;