watchdog: rzv2h: Make "oscclk" and reset controller optional

Update the rzv2h_wdt driver to make the "oscclk" clock and reset
controller optional.

Use devm_clk_get_optional_prepared() to obtain the "oscclk" clock,
allowing the driver to work on platforms that do not provide this clock,
such as the RZ/T2H SoC.

Similarly, use devm_reset_control_get_optional_exclusive() to allow the
driver to function on platforms that lack a reset controller.

These changes are preparatory steps for supporting the RZ/T2H SoC, which
does not provide an "oscclk" clock or a reset controller.

Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
Reviewed-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@linux-watchdog.org>

Author: prabhakarlad

drivers/watchdog/rzv2h_wdt.c

@@ -230,11 +230,11 @@ static int rzv2h_wdt_probe(struct platform_device *pdev)
 	if (IS_ERR(priv->pclk))
 		return dev_err_probe(dev, PTR_ERR(priv->pclk), "no pclk");
 
-	priv->oscclk = devm_clk_get_prepared(dev, "oscclk");
+	priv->oscclk = devm_clk_get_optional_prepared(dev, "oscclk");
 	if (IS_ERR(priv->oscclk))
 		return dev_err_probe(dev, PTR_ERR(priv->oscclk), "no oscclk");
 
-	priv->rstc = devm_reset_control_get_exclusive(dev, NULL);
+	priv->rstc = devm_reset_control_get_optional_exclusive(dev, NULL);
 	if (IS_ERR(priv->rstc))
 		return dev_err_probe(dev, PTR_ERR(priv->rstc),
 				     "failed to get cpg reset");