[RFC PATCH v2] watchdog: sp805: Add clock-frequency property

[Srinath Mannam]

When using ACPI node, binding clock devices are
not available as device tree, So clock-frequency
property given in _DSD object of ACPI device is
used to calculate Watchdog rate.

Signed-off-by: Srinath Mannam <srinath.man...@broadcom.com>
---
 drivers/watchdog/sp805_wdt.c | 34 ++++++++++++++++++++++++++--------
 1 file changed, 26 insertions(+), 8 deletions(-)

diff --git a/drivers/watchdog/sp805_wdt.c b/drivers/watchdog/sp805_wdt.c
index 9849db0..ad5ed64 100644
--- a/drivers/watchdog/sp805_wdt.c
+++ b/drivers/watchdog/sp805_wdt.c
@@ -11,6 +11,7 @@
  * warranty of any kind, whether express or implied.
  */
 
+#include <linux/acpi.h>
 #include <linux/device.h>
 #include <linux/resource.h>
 #include <linux/amba/bus.h>
@@ -22,6 +23,7 @@
 #include <linux/math64.h>
 #include <linux/module.h>
 #include <linux/moduleparam.h>
+#include <linux/of.h>
 #include <linux/pm.h>
 #include <linux/slab.h>
 #include <linux/spinlock.h>
@@ -65,6 +67,7 @@ struct sp805_wdt {
        spinlock_t                      lock;
        void __iomem                    *base;
        struct clk                      *clk;
+       u64                             rate;
        struct amba_device              *adev;
        unsigned int                    load_val;
 };
@@ -80,7 +83,7 @@ static int wdt_setload(struct watchdog_device *wdd, unsigned 
int timeout)
        struct sp805_wdt *wdt = watchdog_get_drvdata(wdd);
        u64 load, rate;
 
-       rate = clk_get_rate(wdt->clk);
+       rate = wdt->rate;
 
        /*
         * sp805 runs counter with given value twice, after the end of first
@@ -106,9 +109,7 @@ static int wdt_setload(struct watchdog_device *wdd, 
unsigned int timeout)
 static unsigned int wdt_timeleft(struct watchdog_device *wdd)
 {
        struct sp805_wdt *wdt = watchdog_get_drvdata(wdd);
-       u64 load, rate;
-
-       rate = clk_get_rate(wdt->clk);
+       u64 load;
 
        spin_lock(&wdt->lock);
        load = readl_relaxed(wdt->base + WDTVALUE);
@@ -118,7 +119,7 @@ static unsigned int wdt_timeleft(struct watchdog_device 
*wdd)
                load += wdt->load_val + 1;
        spin_unlock(&wdt->lock);
 
-       return div_u64(load, rate);
+       return div_u64(load, wdt->rate);
 }
 
 static int
@@ -228,10 +229,27 @@ sp805_wdt_probe(struct amba_device *adev, const struct 
amba_id *id)
        if (IS_ERR(wdt->base))
                return PTR_ERR(wdt->base);
 
-       wdt->clk = devm_clk_get(&adev->dev, NULL);
-       if (IS_ERR(wdt->clk)) {
+       if (adev->dev.of_node) {
+               wdt->clk = devm_clk_get(&adev->dev, NULL);
+               if (IS_ERR(wdt->clk)) {
+                       ret = PTR_ERR(wdt->clk);
+                       wdt->clk = NULL;
+               } else
+                       wdt->rate = clk_get_rate(wdt->clk);
+       } else if (has_acpi_companion(&adev->dev)) {
+               /*
+                * When Driver probe with ACPI device, clock devices
+                * are not available, so watchdog rate get from
+                * clock-frequency property given in _DSD object.
+                */
+               device_property_read_u64(&adev->dev, "clock-frequency",
+                               &wdt->rate);
+               if (!wdt->rate)
+                       ret = -ENODEV;
+       }
+
+       if (ret) {
                dev_warn(&adev->dev, "Clock not found\n");
-               ret = PTR_ERR(wdt->clk);
                goto err;
        }
 
-- 
2.7.4