i2c-bfin-twi: fix CLKDIV calculation

Calculation of the CLKDIV speed setting should be done using base 10 math
rather than base 2.  We also avoid exceeding the spec due to integer
truncation and a 50% duty cycle.

Signed-off-by: Sonic Zhang <sonic.zhang@analog.com>
Signed-off-by: Mike Frysinger <vapier@gentoo.org>
Signed-off-by: Ben Dooks <ben-linux@fluff.org>

drivers/i2c/busses/i2c-bfin-twi.c

@@ -693,13 +693,13 @@ static int i2c_bfin_twi_probe(struct platform_device *pdev)
 	}
 
 	/* Set TWI internal clock as 10MHz */
-	write_CONTROL(iface, ((get_sclk() / 1024 / 1024 + 5) / 10) & 0x7F);
+	write_CONTROL(iface, ((get_sclk() / 1000 / 1000 + 5) / 10) & 0x7F);
 
 	/*
 	 * We will not end up with a CLKDIV=0 because no one will specify
-	 * 20kHz SCL or less in Kconfig now. (5 * 1024 / 20 = 0x100)
+	 * 20kHz SCL or less in Kconfig now. (5 * 1000 / 20 = 250)
 	 */
-	clkhilow = 5 * 1024 / CONFIG_I2C_BLACKFIN_TWI_CLK_KHZ;
+	clkhilow = ((10 * 1000 / CONFIG_I2C_BLACKFIN_TWI_CLK_KHZ) + 1) / 2;
 
 	/* Set Twi interface clock as specified */
 	write_CLKDIV(iface, (clkhilow << 8) | clkhilow);