power/reset: at91-reset: get and use slow clock

Commit dca1a4b5ff6e ("clk: at91: keep slow clk enabled to prevent system
hang") added a workaround for the slow clock as it is not properly handled
by its users.

Get and use the slow clock as it is necessary for the at91 reset
controller.

Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
Signed-off-by: Sebastian Reichel <sre@kernel.org>

diff --git a/drivers/power/reset/at91-reset.c b/drivers/power/reset/at91-reset.c
index 6374f5c9ee91b02b6df62a062b185e091153d92c..3d9c43a66806c630082c7c9a0c2aad8d79a20f0d 100644 (file)
--- a/drivers/power/reset/at91-reset.c
+++ b/drivers/power/reset/at91-reset.c
@@ -11,6 +11,7 @@
  * warranty of any kind, whether express or implied.
  */
 
+#include <linux/clk.h>
 #include <linux/io.h>
 #include <linux/module.h>
 #include <linux/of_address.h>
@@ -46,6 +47,7 @@ enum reset_type {
 };
 
 static void __iomem *at91_ramc_base[2], *at91_rstc_base;
+static struct clk *sclk;
 
 /*
 * unless the SDRAM is cleanly shutdown before we hit the
@@ -205,9 +207,21 @@ static int __init at91_reset_probe(struct platform_device *pdev)
        match = of_match_node(at91_reset_of_match, pdev->dev.of_node);
        at91_restart_nb.notifier_call = match->data;
 
+       sclk = devm_clk_get(&pdev->dev, NULL);
+       if (IS_ERR(sclk))
+               return PTR_ERR(sclk);
+
+       ret = clk_prepare_enable(sclk);
+       if (ret) {
+               dev_err(&pdev->dev, "Could not enable slow clock\n");
+               return ret;
+       }
+
        ret = register_restart_handler(&at91_restart_nb);
-       if (ret)
+       if (ret) {
+               clk_disable_unprepare(sclk);
                return ret;
+       }
 
        at91_reset_status(pdev);
 
@@ -217,6 +231,7 @@ static int __init at91_reset_probe(struct platform_device *pdev)
 static int __exit at91_reset_remove(struct platform_device *pdev)
 {
        unregister_restart_handler(&at91_restart_nb);
+       clk_disable_unprepare(sclk);
 
        return 0;
 }