linux-kernel - [PATCH] clk: fractional-divider: prevent division by zero

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Date:	Fri, 16 Jan 2015 14:37:50 +0200
From:	Heikki Krogerus <heikki.krogerus@...ux.intel.com>
To:	Mike Turquette <mturquette@...aro.org>,
	Stephen Boyd <sboyd@...eaurora.org>
Cc:	Mika Westerberg <mika.westerberg@...ux.intel.com>,
	Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
	linux-kernel@...r.kernel.org
Subject: [PATCH] clk: fractional-divider: prevent division by zero

Preventing division by zero condition by making sure that
the initial n and m values are not 0.

Signed-off-by: Heikki Krogerus <heikki.krogerus@...ux.intel.com>
---
 drivers/clk/clk-fractional-divider.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/drivers/clk/clk-fractional-divider.c b/drivers/clk/clk-fractional-divider.c
index 82a59d0..dc91da7 100644
--- a/drivers/clk/clk-fractional-divider.c
+++ b/drivers/clk/clk-fractional-divider.c
@@ -104,6 +104,7 @@ struct clk *clk_register_fractional_divider(struct device *dev,
 	struct clk_fractional_divider *fd;
 	struct clk_init_data init;
 	struct clk *clk;
+	u32 val;
 
 	fd = kzalloc(sizeof(*fd), GFP_KERNEL);
 	if (!fd) {
@@ -126,6 +127,14 @@ struct clk *clk_register_fractional_divider(struct device *dev,
 	fd->lock = lock;
 	fd->hw.init = &init;
 
+	/* Prevent division by zero */
+	val = clk_readl(fd->reg);
+	if (!(val & fd->nmask))
+		val |= 1 << fd->nshift;
+	if (!(val & fd->mmask))
+		val |= 1 << fd->mshift;
+	clk_writel(val, fd->reg);
+
 	clk = clk_register(dev, &fd->hw);
 	if (IS_ERR(clk))
 		kfree(fd);
-- 
2.1.4

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