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

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Date:   Mon,  9 Jul 2018 15:49:29 +0530
From:   Srinath Mannam <srinath.mannam@...adcom.com>
To:     wim@...ux-watchdog.org, linux@...ck-us.net
Cc:     ray.jui@...adcom.com, vladimir.olovyannikov@...adcom.com,
        vikram.prakash@...adcom.com, scott.branden@...adcom.com,
        sudeep.holla@....com, linux-watchdog@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Srinath Mannam <srinath.mannam@...adcom.com>
Subject: [RFC PATCH v2] watchdog: sp805: Add clock-frequency property

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.mannam@...adcom.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