serial: max310x: Use clock-names property matching to recognize EXTCLK

Dennis reported that on ACPI-based systems the clock frequency
isn't enough to configure device properly. We have to respect
the clock source as well. To achieve this match the clock-names
property against "osc" to recognize external clock connection.
On DT-based system this doesn't change anything.

Reported-and-tested-by: Dennis Giaya <dgiaya@whoi.edu>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20210723125943.22039-1-andriy.shevchenko@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/tty/serial/max310x.c b/drivers/tty/serial/max310x.c
index 0c1e4df52215391a2b27629207e30a3bd12a3aaf..c2929fefce809dbddd877e0eb6c1151f7e916986 100644 (file)
--- a/drivers/tty/serial/max310x.c
+++ b/drivers/tty/serial/max310x.c
@@ -1271,18 +1271,13 @@ static int max310x_probe(struct device *dev, const struct max310x_devtype *devty
        /* Always ask for fixed clock rate from a property. */
        device_property_read_u32(dev, "clock-frequency", &uartclk);
 
-       s->clk = devm_clk_get_optional(dev, "osc");
+       xtal = device_property_match_string(dev, "clock-names", "osc") < 0;
+       if (xtal)
+               s->clk = devm_clk_get_optional(dev, "xtal");
+       else
+               s->clk = devm_clk_get_optional(dev, "osc");
        if (IS_ERR(s->clk))
                return PTR_ERR(s->clk);
-       if (s->clk) {
-               xtal = false;
-       } else {
-               s->clk = devm_clk_get_optional(dev, "xtal");
-               if (IS_ERR(s->clk))
-                       return PTR_ERR(s->clk);
-
-               xtal = true;
-       }
 
        ret = clk_prepare_enable(s->clk);
        if (ret)