can: mscan: improve clock API use

the .get_clock() callback is run from probe() and might allocate
resources, introduce a .put_clock() callback that is run from remove()
to undo any allocation activities

prepare and enable the clocks in open(), disable and unprepare the
clocks in close() if clocks were acquired during probe(), to not assume
knowledge about which activities are done in probe() and remove()

use devm_get_clk() to lookup the SYS and REF clocks, to have the clocks
put upon device shutdown

store pointers to data structures upon successful allocation already
instead of deferral until complete setup, such that subroutines in the
setup sequence may access those data structures as well to track their
resource acquisition

since clock allocation remains optional, the release callback as well as
the enable/disable calls in open/close are optional as well

Cc: linux-can@vger.kernel.org
Cc: netdev@vger.kernel.org
Signed-off-by: Gerhard Sittig <gsi@denx.de>
Signed-off-by: Anatolij Gustschin <agust@denx.de>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

1 files changed, 24 insertions, 1 deletions

diff --git a/drivers/net/can/mscan/mscan.c b/drivers/net/can/mscan/mscan.c
index e6b40954e204..a955ec8c4b97 100644
--- a/drivers/net/can/mscan/mscan.c
+++ b/drivers/net/can/mscan/mscan.c
@@ -573,10 +573,21 @@ static int mscan_open(struct net_device *dev)
 	struct mscan_priv *priv = netdev_priv(dev);
 	struct mscan_regs __iomem *regs = priv->reg_base;
 
+	if (priv->clk_ipg) {
+		ret = clk_prepare_enable(priv->clk_ipg);
+		if (ret)
+			goto exit_retcode;
+	}
+	if (priv->clk_can) {
+		ret = clk_prepare_enable(priv->clk_can);
+		if (ret)
+			goto exit_dis_ipg_clock;
+	}
+
 	/* common open */
 	ret = open_candev(dev);
 	if (ret)
-		return ret;
+		goto exit_dis_can_clock;
 
 	napi_enable(&priv->napi);
 
@@ -604,6 +615,13 @@ exit_free_irq:
 exit_napi_disable:
 	napi_disable(&priv->napi);
 	close_candev(dev);
+exit_dis_can_clock:
+	if (priv->clk_can)
+		clk_disable_unprepare(priv->clk_can);
+exit_dis_ipg_clock:
+	if (priv->clk_ipg)
+		clk_disable_unprepare(priv->clk_ipg);
+exit_retcode:
 	return ret;
 }
 
@@ -621,6 +639,11 @@ static int mscan_close(struct net_device *dev)
 	close_candev(dev);
 	free_irq(dev->irq, dev);
 
+	if (priv->clk_can)
+		clk_disable_unprepare(priv->clk_can);
+	if (priv->clk_ipg)
+		clk_disable_unprepare(priv->clk_ipg);
+
 	return 0;
 }