openwrt/target/linux/layerscape/patches-5.4/808-i2c-0006-MLK-20368-i2c-imx-Coverity-fix-divide-by-zero-warnin.patch

From 2c2c7e16ad0401f85dd8ff9bc0789fa10e715c0e Mon Sep 17 00:00:00 2001
From: Clark Wang <xiaoning.wang@nxp.com>
Date: Tue, 15 Jan 2019 10:04:30 +0800
Subject: [PATCH] MLK-20368 i2c-imx: Coverity: fix divide by zero warning

"i2c_clk_rate / 2" might be zero when the i2c_clk_rate gets the clock is
0 or 1, so add a judgment to avoid the denominator is equal to 0.

Signed-off-by: Clark Wang <xiaoning.wang@nxp.com>
[Arul: Add support to check return value everywhere in the driver]
Signed-off-by: Arulpandiyan Vadivel <arulpandiyan_vadivel@mentor.com>

Signed-off-by: Shrikant Bobade <Shrikant_Bobade@mentor.com>
(cherry picked from commit d382de595bffc0975ab7c0582e08dd4f7afc0c1a)
(cherry picked from commit 456caa9ba270ca8f4f962918a0625d1a8348f316)
---
 drivers/i2c/busses/i2c-imx.c | 31 +++++++++++++++++++++++++------
 1 file changed, 25 insertions(+), 6 deletions(-)

--- a/drivers/i2c/busses/i2c-imx.c
+++ b/drivers/i2c/busses/i2c-imx.c
@@ -492,16 +492,24 @@ static int i2c_imx_acked(struct imx_i2c_
 	return 0;
 }
 
-static void i2c_imx_set_clk(struct imx_i2c_struct *i2c_imx,
+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;
 	int i;
 
-	/* 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.
+	 */
+
+	/* Divider value calculation */
+	if (!(i2c_clk_rate / 2))
+		return -EINVAL;
 
 	i2c_imx->cur_clk = i2c_clk_rate;
 
@@ -532,20 +540,23 @@ static void i2c_imx_set_clk(struct imx_i
 	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,
 				     unsigned long action, void *data)
 {
+	int ret = 0;
 	struct clk_notifier_data *ndata = data;
 	struct imx_i2c_struct *i2c_imx = container_of(nb,
 						      struct imx_i2c_struct,
 						      clk_change_nb);
 
 	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)
@@ -555,6 +566,10 @@ static int i2c_imx_start(struct imx_i2c_
 
 	dev_dbg(&i2c_imx->adapter.dev, "<%s>\n", __func__);
 
+	result = i2c_imx_set_clk(i2c_imx, clk_get_rate(i2c_imx->clk));
+	if (result)
+		return result;
+
 	imx_i2c_write_reg(i2c_imx->ifdr, i2c_imx, IMX_I2C_IFDR);
 	/* Enable I2C controller */
 	imx_i2c_write_reg(i2c_imx->hwdata->i2sr_clr_opcode, i2c_imx, IMX_I2C_I2SR);
@@ -1175,7 +1190,11 @@ static int i2c_imx_probe(struct platform
 		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;
+	}
 
 	/*
 	 * This limit caused by an i.MX7D hardware issue(e7805 in Errata).