can: flexcan: flexcan_get_berr_counter(): switch on clocks before accessing ecr register

The funcion flexcan_get_berr_counter() may be called from userspace even if the
interface is down, this the clocks are disabled. This patch switches on the
clocks before accessing the ecr register.

Reported-by: Ashutosh Singh <ashuleapyear@gmail.com>
Signed-off-by: Stefan Agner <stefan@agner.ch>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

1 files changed, 27 insertions, 3 deletions

diff --git a/drivers/net/can/flexcan.c b/drivers/net/can/flexcan.c
index f425ec2c7839..6bfe24aefea0 100644
--- a/drivers/net/can/flexcan.c
+++ b/drivers/net/can/flexcan.c
@@ -378,8 +378,9 @@ static int flexcan_chip_softreset(struct flexcan_priv *priv)
         return 0;
 }
 
-static int flexcan_get_berr_counter(const struct net_device *dev,
-                                    struct can_berr_counter *bec)
+
+static int __flexcan_get_berr_counter(const struct net_device *dev,
+                                      struct can_berr_counter *bec)
 {
         const struct flexcan_priv *priv = netdev_priv(dev);
         struct flexcan_regs __iomem *regs = priv->base;
@@ -391,6 +392,29 @@ static int flexcan_get_berr_counter(const struct net_device *dev,
         return 0;
 }
 
+static int flexcan_get_berr_counter(const struct net_device *dev,
+                                    struct can_berr_counter *bec)
+{
+        const struct flexcan_priv *priv = netdev_priv(dev);
+        int err;
+
+        err = clk_prepare_enable(priv->clk_ipg);
+        if (err)
+                return err;
+
+        err = clk_prepare_enable(priv->clk_per);
+        if (err)
+                goto out_disable_ipg;
+
+        err = __flexcan_get_berr_counter(dev, bec);
+
+        clk_disable_unprepare(priv->clk_per);
+ out_disable_ipg:
+        clk_disable_unprepare(priv->clk_ipg);
+
+        return err;
+}
+
 static int flexcan_start_xmit(struct sk_buff *skb, struct net_device *dev)
 {
         const struct flexcan_priv *priv = netdev_priv(dev);
@@ -503,7 +527,7 @@ static void do_state(struct net_device *dev,
         struct flexcan_priv *priv = netdev_priv(dev);
         struct can_berr_counter bec;
 
-        flexcan_get_berr_counter(dev, &bec);
+        __flexcan_get_berr_counter(dev, &bec);
 
         switch (priv->can.state) {
         case CAN_STATE_ERROR_ACTIVE: