linux-kernel - [PATCH 1/2] watchdog: of_xilinx_wdt: Add support for reading freq via CCF

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Message-Id: <d081ea43fc2b3b75cae2e19716920e1bb6c81328.1502105061.git.michal.simek@xilinx.com>
Date:   Mon,  7 Aug 2017 13:24:22 +0200
From:   Michal Simek <michal.simek@...inx.com>
To:     linux-kernel@...r.kernel.org, monstr@...str.eu
Cc:     Maulik Jodhani <maulik.jodhani@...inx.com>,
        Sören Brinkmann <soren.brinkmann@...inx.com>,
        Guenter Roeck <linux@...ck-us.net>,
        linux-watchdog@...r.kernel.org, Wim Van Sebroeck <wim@...ana.be>,
        linux-arm-kernel@...ts.infradead.org
Subject: [PATCH 1/2] watchdog: of_xilinx_wdt: Add support for reading freq via CCF

From: Maulik Jodhani <maulik.jodhani@...inx.com>

Improve CLK handling in the code to read freq via CCF.
Also disable CLK asap and add clk handling code to start and stop.

Signed-off-by: Maulik Jodhani <maulik.jodhani@...inx.com>
Signed-off-by: Michal Simek <michal.simek@...inx.com>
---

 drivers/watchdog/of_xilinx_wdt.c | 45 ++++++++++++++++++++++++++++------------
 1 file changed, 32 insertions(+), 13 deletions(-)

diff --git a/drivers/watchdog/of_xilinx_wdt.c b/drivers/watchdog/of_xilinx_wdt.c
index fae7fe929ea3..41edeb93a327 100644
--- a/drivers/watchdog/of_xilinx_wdt.c
+++ b/drivers/watchdog/of_xilinx_wdt.c
@@ -51,9 +51,16 @@ struct xwdt_device {
 
 static int xilinx_wdt_start(struct watchdog_device *wdd)
 {
+	int ret;
 	u32 control_status_reg;
 	struct xwdt_device *xdev = watchdog_get_drvdata(wdd);
 
+	ret = clk_enable(xdev->clk);
+	if (ret) {
+		dev_err(wdd->parent, "Failed to enable clock\n");
+		return ret;
+	}
+
 	spin_lock(&xdev->spinlock);
 
 	/* Clean previous status and enable the watchdog timer */
@@ -85,6 +92,9 @@ static int xilinx_wdt_stop(struct watchdog_device *wdd)
 	iowrite32(0, xdev->base + XWT_TWCSR1_OFFSET);
 
 	spin_unlock(&xdev->spinlock);
+
+	clk_disable(xdev->clk);
+
 	pr_info("Stopped!\n");
 
 	return 0;
@@ -167,11 +177,6 @@ static int xwdt_probe(struct platform_device *pdev)
 	if (IS_ERR(xdev->base))
 		return PTR_ERR(xdev->base);
 
-	rc = of_property_read_u32(pdev->dev.of_node, "clock-frequency", &pfreq);
-	if (rc)
-		dev_warn(&pdev->dev,
-			 "The watchdog clock frequency cannot be obtained\n");
-
 	rc = of_property_read_u32(pdev->dev.of_node, "xlnx,wdt-interval",
 				  &xdev->wdt_interval);
 	if (rc)
@@ -186,6 +191,26 @@ static int xwdt_probe(struct platform_device *pdev)
 
 	watchdog_set_nowayout(xilinx_wdt_wdd, enable_once);
 
+	xdev->clk = devm_clk_get(&pdev->dev, NULL);
+	if (IS_ERR(xdev->clk)) {
+		if (PTR_ERR(xdev->clk) != -ENOENT)
+			return PTR_ERR(xdev->clk);
+
+		/*
+		 * Clock framework support is optional, continue on
+		 * anyways if we don't find a matching clock.
+		 */
+		xdev->clk = NULL;
+
+		rc = of_property_read_u32(pdev->dev.of_node, "clock-frequency",
+					  &pfreq);
+		if (rc)
+			dev_warn(&pdev->dev,
+				 "The watchdog clock freq cannot be obtained\n");
+	} else {
+		pfreq = clk_get_rate(xdev->clk);
+	}
+
 	/*
 	 * Twice of the 2^wdt_interval / freq  because the first wdt overflow is
 	 * ignored (interrupt), reset is only generated at second wdt overflow
@@ -197,14 +222,6 @@ static int xwdt_probe(struct platform_device *pdev)
 	spin_lock_init(&xdev->spinlock);
 	watchdog_set_drvdata(xilinx_wdt_wdd, xdev);
 
-	xdev->clk = devm_clk_get(&pdev->dev, NULL);
-	if (IS_ERR(xdev->clk)) {
-		if (PTR_ERR(xdev->clk) == -ENOENT)
-			xdev->clk = NULL;
-		else
-			return PTR_ERR(xdev->clk);
-	}
-
 	rc = clk_prepare_enable(xdev->clk);
 	if (rc) {
 		dev_err(&pdev->dev, "unable to enable clock\n");
@@ -223,6 +240,8 @@ static int xwdt_probe(struct platform_device *pdev)
 		goto err_clk_disable;
 	}
 
+	clk_disable(xdev->clk);
+
 	dev_info(&pdev->dev, "Xilinx Watchdog Timer at %p with timeout %ds\n",
 		 xdev->base, xilinx_wdt_wdd->timeout);
 
-- 
1.9.1