i2c: altera: Fix potential integer overflow

commit 54498e8070e19e74498a72c7331348143e7e1f8c upstream.

Factor out 100 from the equation and do 32-bit arithmetic (3 * clk_mhz / 10)
instead of 64-bit.

Notice that clk_mhz is MHz, so the multiplication will never wrap 32 bits
and there is no need for div_u64().

Addresses-Coverity: 1458369 ("Unintentional integer overflow")
Fixes: 0560ad576268 ("i2c: altera: Add Altera I2C Controller driver")
Suggested-by: David Laight <David.Laight@ACULAB.COM>
Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Reviewed-by: Thor Thayer <thor.thayer@linux.intel.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/i2c/busses/i2c-altera.c b/drivers/i2c/busses/i2c-altera.c
index f5e1941e65b5a2dd6cebfd8a2f60798e258b986b..a1cdcfc74acf6f8d55d23e20c2adb4b92a388784 100644 (file)
--- a/drivers/i2c/busses/i2c-altera.c
+++ b/drivers/i2c/busses/i2c-altera.c
@@ -182,7 +182,7 @@ static void altr_i2c_init(struct altr_i2c_dev *idev)
        /* SCL Low Time */
        writel(t_low, idev->base + ALTR_I2C_SCL_LOW);
        /* SDA Hold Time, 300ns */
-       writel(div_u64(300 * clk_mhz, 1000), idev->base + ALTR_I2C_SDA_HOLD);
+       writel(3 * clk_mhz / 10, idev->base + ALTR_I2C_SDA_HOLD);
 
        /* Mask all master interrupt bits */
        altr_i2c_int_enable(idev, ALTR_I2C_ALL_IRQ, false);