linux-kernel - [PATCH] i2c: imx: fix divide by zero warning

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Message-Id: <20241125135019.1612030-1-carlos.song@nxp.com>
Date: Mon, 25 Nov 2024 21:50:19 +0800
From: carlos.song@....com
To: o.rempel@...gutronix.de,
	kernel@...gutronix.de,
	andi.shyti@...nel.org,
	shawnguo@...nel.org,
	s.hauer@...gutronix.de,
	festevam@...il.com,
	frank.li@....com
Cc: linux-i2c@...r.kernel.org,
	imx@...ts.linux.dev,
	linux-arm-kernel@...ts.infradead.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH] i2c: imx: fix divide by zero warning

From: Carlos Song <carlos.song@....com>

Add "i2c_clk_rate / 2" check to avoid "divide by zero warning".
i2c_clk_rate may be zero if i2c clock is disabled.

Signed-off-by: Carlos Song <carlos.song@....com>
Signed-off-by: Clark Wang <xiaoning.wang@....com>
Signed-off-by: Haibo Chen <haibo.chen@....com>
---
 drivers/i2c/busses/i2c-imx.c | 23 +++++++++++++++++------
 1 file changed, 17 insertions(+), 6 deletions(-)

diff --git a/drivers/i2c/busses/i2c-imx.c b/drivers/i2c/busses/i2c-imx.c
index 2c782cdc26bd..5ed4cb61e262 100644
--- a/drivers/i2c/busses/i2c-imx.c
+++ b/drivers/i2c/busses/i2c-imx.c
@@ -623,8 +623,8 @@ static int i2c_imx_acked(struct imx_i2c_struct *i2c_imx)
 	return 0;
 }
 
-static void i2c_imx_set_clk(struct imx_i2c_struct *i2c_imx,
-			    unsigned int i2c_clk_rate)
+static int i2c_imx_set_clk(struct imx_i2c_struct *i2c_imx,
+			   unsigned int i2c_clk_rate)
 {
 	struct imx_i2c_clk_pair *i2c_clk_div = i2c_imx->hwdata->clk_div;
 	unsigned int div;
@@ -639,7 +639,11 @@ static void i2c_imx_set_clk(struct imx_i2c_struct *i2c_imx,
 
 	/* Divider value calculation */
 	if (i2c_imx->cur_clk == i2c_clk_rate)
-		return;
+		return 0;
+
+	/* Keep the denominator of the following program always NOT equal to 0. */
+	if (!(i2c_clk_rate / 2))
+		return -EINVAL;
 
 	i2c_imx->cur_clk = i2c_clk_rate;
 
@@ -670,6 +674,8 @@ static void i2c_imx_set_clk(struct imx_i2c_struct *i2c_imx,
 	dev_dbg(&i2c_imx->adapter.dev, "IFDR[IC]=0x%x, REAL DIV=%d\n",
 		i2c_clk_div[i].val, i2c_clk_div[i].div);
 #endif
+
+	return 0;
 }
 
 static int i2c_imx_clk_notifier_call(struct notifier_block *nb,
@@ -679,11 +685,12 @@ static int i2c_imx_clk_notifier_call(struct notifier_block *nb,
 	struct imx_i2c_struct *i2c_imx = container_of(nb,
 						      struct imx_i2c_struct,
 						      clk_change_nb);
+	int ret = 0;
 
 	if (action & POST_RATE_CHANGE)
-		i2c_imx_set_clk(i2c_imx, ndata->new_rate);
+		ret = i2c_imx_set_clk(i2c_imx, ndata->new_rate);
 
-	return NOTIFY_OK;
+	return notifier_from_errno(ret);
 }
 
 static int i2c_imx_start(struct imx_i2c_struct *i2c_imx, bool atomic)
@@ -1782,7 +1789,11 @@ static int i2c_imx_probe(struct platform_device *pdev)
 		i2c_imx->bitrate = pdata->bitrate;
 	i2c_imx->clk_change_nb.notifier_call = i2c_imx_clk_notifier_call;
 	clk_notifier_register(i2c_imx->clk, &i2c_imx->clk_change_nb);
-	i2c_imx_set_clk(i2c_imx, clk_get_rate(i2c_imx->clk));
+	ret = i2c_imx_set_clk(i2c_imx, clk_get_rate(i2c_imx->clk));
+	if (ret < 0) {
+		dev_err(&pdev->dev, "can't get I2C clock\n");
+		goto clk_notifier_unregister;
+	}
 
 	i2c_imx_reset_regs(i2c_imx);
 
-- 
2.34.1