i2c: thunderx: ACPI support for clock settings

Add support for reading the system clock and the TWSI clock
frequency from ACPI DSDT.

TWSI clock was already covered by using device_property_read().
Signed-off-by: NJan Glauber <jglauber@cavium.com>
Signed-off-by: NWolfram Sang <wsa@the-dreams.de>

drivers/i2c/busses/i2c-thunderx-pcidrv.c

@@ -85,17 +85,23 @@ static void thunder_i2c_clock_enable(struct device *dev, struct octeon_i2c *i2c)
 {
 	int ret;
 
-	i2c->clk = clk_get(dev, NULL);
-	if (IS_ERR(i2c->clk)) {
-		i2c->clk = NULL;
-		goto skip;
+	if (acpi_disabled) {
+		/* DT */
+		i2c->clk = clk_get(dev, NULL);
+		if (IS_ERR(i2c->clk)) {
+			i2c->clk = NULL;
+			goto skip;
+		}
+
+		ret = clk_prepare_enable(i2c->clk);
+		if (ret)
+			goto skip;
+		i2c->sys_freq = clk_get_rate(i2c->clk);
+	} else {
+		/* ACPI */
+		device_property_read_u32(dev, "sclk", &i2c->sys_freq);
 	}
 
-	ret = clk_prepare_enable(i2c->clk);
-	if (ret)
-		goto skip;
-	i2c->sys_freq = clk_get_rate(i2c->clk);
-
 skip:
 	if (!i2c->sys_freq)
 		i2c->sys_freq = SYS_FREQ_DEFAULT;