[PATCH 3.18 45/85] w1: mxc_w1: Enable clock before calling clk_get_rate() on it

[Greg Kroah-Hartman]

3.18-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Stefan Potyra <stefan.pot...@elektrobit.com>

commit 955bc61328dc0a297fb3baccd84e9d3aee501ed8 upstream.

According to the API, you may only call clk_get_rate() after actually
enabling it.

Found by Linux Driver Verification project (linuxtesting.org).

Fixes: a5fd9139f74c ("w1: add 1-wire master driver for i.MX27 / i.MX31")
Signed-off-by: Stefan Potyra <stefan.pot...@elektrobit.com>
Acked-by: Evgeniy Polyakov <z...@ioremap.net>
Cc: stable <sta...@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>

---
 drivers/w1/masters/mxc_w1.c |   20 +++++++++++++-------
 1 file changed, 13 insertions(+), 7 deletions(-)

--- a/drivers/w1/masters/mxc_w1.c
+++ b/drivers/w1/masters/mxc_w1.c
@@ -113,6 +113,10 @@ static int mxc_w1_probe(struct platform_
        if (IS_ERR(mdev->clk))
                return PTR_ERR(mdev->clk);
 
+       err = clk_prepare_enable(mdev->clk);
+       if (err)
+               return err;
+
        clkrate = clk_get_rate(mdev->clk);
        if (clkrate < 10000000)
                dev_warn(&pdev->dev,
@@ -126,12 +130,10 @@ static int mxc_w1_probe(struct platform_
 
        res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
        mdev->regs = devm_ioremap_resource(&pdev->dev, res);
-       if (IS_ERR(mdev->regs))
-               return PTR_ERR(mdev->regs);
-
-       err = clk_prepare_enable(mdev->clk);
-       if (err)
-               return err;
+       if (IS_ERR(mdev->regs)) {
+               err = PTR_ERR(mdev->regs);
+               goto out_disable_clk;
+       }
 
        /* Software reset 1-Wire module */
        writeb(MXC_W1_RESET_RST, mdev->regs + MXC_W1_RESET);
@@ -147,8 +149,12 @@ static int mxc_w1_probe(struct platform_
 
        err = w1_add_master_device(&mdev->bus_master);
        if (err)
-               clk_disable_unprepare(mdev->clk);
+               goto out_disable_clk;
+
+       return 0;
 
+out_disable_clk:
+       clk_disable_unprepare(mdev->clk);
        return err;
 }