i2c: designware_i2c.c: Add support for the "i2c probe" command

i2c_probe() is changed to reinit the i2c bus upon read failure.
This is naturally the case upon i2c bus probing.

Also, some printf messages upon read failure are removed. As they
would interfere with the "i2c probe" command.

Additionally, i2c_set_bus_speed() now returns 0, so that the
"i2c speed" command can be used.

Signed-off-by: Stefan Roese <sr@denx.de>
Cc: Amit Virdi <amit.virdi@st.com>
Cc: Vipin Kumar <vipin.kumar@st.com>

drivers/i2c/designware_i2c.c

@@ -90,7 +90,7 @@ static void set_speed(int i2c_spd)
  *
  * Set the i2c speed.
  */
-void i2c_set_bus_speed(int speed)
+int i2c_set_bus_speed(int speed)
 {
 	if (speed >= I2C_MAX_SPEED)
 		set_speed(IC_SPEED_MODE_MAX);
@@ -98,6 +98,8 @@ void i2c_set_bus_speed(int speed)
 		set_speed(IC_SPEED_MODE_FAST);
 	else
 		set_speed(IC_SPEED_MODE_STANDARD);
+
+	return 0;
 }
 
 /*
@@ -215,10 +217,8 @@ static int check_params(uint addr, int alen, uchar *buffer, int len)
 
 static int i2c_xfer_init(uchar chip, uint addr)
 {
-	if (i2c_wait_for_bb()) {
-		printf("Timed out waiting for bus\n");
+	if (i2c_wait_for_bb())
 		return 1;
-	}
 
 	i2c_setaddress(chip);
 	writel(addr, &i2c_regs_p->ic_cmd_data);
@@ -282,7 +282,6 @@ int i2c_read(uchar chip, uint addr, int alen, uchar *buffer, int len)
 			start_time_rx = get_timer(0);
 
 		} else if (get_timer(start_time_rx) > I2C_BYTE_TO) {
-				printf("Timed out. i2c read Failed\n");
 				return 1;
 		}
 	}
@@ -334,9 +333,14 @@ int i2c_write(uchar chip, uint addr, int alen, uchar *buffer, int len)
 int i2c_probe(uchar chip)
 {
 	u32 tmp;
+	int ret;
 
 	/*
 	 * Try to read the first location of the chip.
 	 */
-	return i2c_read(chip, 0, 1, (uchar *)&tmp, 1);
+	ret = i2c_read(chip, 0, 1, (uchar *)&tmp, 1);
+	if (ret)
+		i2c_init(CONFIG_SYS_I2C_SPEED, CONFIG_SYS_I2C_SLAVE);
+
+	return ret;
 }