gpio: mvebu: Add clk support to prevent lockup

The kirkwood SoC GPIO cores use the runit clock. Add code to
clk_prepare_enable() runit, otherwise there is a danger of locking up
the SoC by accessing the GPIO registers when runit clock is not
ticking.

Reported-by: Simon Baatz <gmbnomis@gmail.com>
Signed-off-by: Andrew Lunn <andrew@lunn.ch>
Tested-by: Simon Baatz <gmbnomis@gmail.com>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Jason Cooper <jason@lakedaemon.net>

1 files changed, 7 insertions, 0 deletions

diff --git a/drivers/gpio/gpio-mvebu.c b/drivers/gpio/gpio-mvebu.c
index 7472182967ce..61a6fde6c089 100644
--- a/drivers/gpio/gpio-mvebu.c
+++ b/drivers/gpio/gpio-mvebu.c
@@ -42,6 +42,7 @@
 #include <linux/io.h>
 #include <linux/of_irq.h>
 #include <linux/of_device.h>
+#include <linux/clk.h>
 #include <linux/pinctrl/consumer.h>
 
 /*
@@ -496,6 +497,7 @@ static int mvebu_gpio_probe(struct platform_device *pdev)
         struct resource *res;
         struct irq_chip_generic *gc;
         struct irq_chip_type *ct;
+        struct clk *clk;
         unsigned int ngpios;
         int soc_variant;
         int i, cpu, id;
@@ -529,6 +531,11 @@ static int mvebu_gpio_probe(struct platform_device *pdev)
                 return id;
         }
 
+        clk = devm_clk_get(&pdev->dev, NULL);
+        /* Not all SoCs require a clock.*/
+        if (!IS_ERR(clk))
+                clk_prepare_enable(clk);
+
         mvchip->soc_variant = soc_variant;
         mvchip->chip.label = dev_name(&pdev->dev);
         mvchip->chip.dev = &pdev->dev;