rtc: jz4740: Add support for JZ4760 SoC

The WENR feature (set a magic value to enable RTC registers read-write)
first appeared on the JZ4760; the JZ4780 came much later.

Since it would be dangerous to specify a newer SoC's compatible string as
the fallback of an older SoC's compatible string, we add support for the
"ingenic,jz4760-rtc" compatible string in the driver.

This will permit to support the JZ4770 by having:
compatible = "ingenic,jz4770-rtc", "ingenic,jz4760-rtc";

Instead of doing:
compatible = "ingenic,jz4770-rtc", "ingenic,jz4780-rtc";

Signed-off-by: Paul Cercueil <paul@crapouillou.net>
Link: https://lore.kernel.org/r/20200311182318.22154-1-paul@crapouillou.net
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

drivers/rtc/rtc-jz4740.c

@@ -46,6 +46,7 @@
 
 enum jz4740_rtc_type {
 	ID_JZ4740,
+	ID_JZ4760,
 	ID_JZ4780,
 };
 
@@ -106,7 +107,7 @@ static inline int jz4740_rtc_reg_write(struct jz4740_rtc *rtc, size_t reg,
 {
 	int ret = 0;
 
-	if (rtc->type >= ID_JZ4780)
+	if (rtc->type >= ID_JZ4760)
 		ret = jz4780_rtc_enable_write(rtc);
 	if (ret == 0)
 		ret = jz4740_rtc_wait_write_ready(rtc);
@@ -298,6 +299,7 @@ static void jz4740_rtc_power_off(void)
 
 static const struct of_device_id jz4740_rtc_of_match[] = {
 	{ .compatible = "ingenic,jz4740-rtc", .data = (void *)ID_JZ4740 },
+	{ .compatible = "ingenic,jz4760-rtc", .data = (void *)ID_JZ4760 },
 	{ .compatible = "ingenic,jz4780-rtc", .data = (void *)ID_JZ4780 },
 	{},
 };