rtc: rx8025: add support for EPSON RX8035.

The RX8035 is a newer model from EPSON which is
very similar in operation to the RX8025.

The changes mirror similar ones that will be
in Linux 5.15:
https://lore.kernel.org/all/20210709044518.28769-2-matt@traverse.com.au/

The UBOOT_DRIVER ID has also been corrected, previously
it declared itself as rx8010sj_rtc which is a different driver.

Signed-off-by: Mathew McBride <matt@traverse.com.au>

diff --git a/drivers/rtc/rx8025.c b/drivers/rtc/rx8025.c
index 36e5b01..09bf365 100644 (file)
--- a/drivers/rtc/rx8025.c
+++ b/drivers/rtc/rx8025.c
@@ -24,6 +24,11 @@
 #endif
 /*---------------------------------------------------------------------*/
 
+enum rx_model {
+       model_rx_8025,
+       model_rx_8035,
+};
+
 /*
  * RTC register addresses
  */
@@ -64,6 +69,20 @@
 
 static int rtc_write(struct udevice *dev, uchar reg, uchar val);
 
+static int rx8025_is_osc_stopped(enum rx_model model, int ctrl2)
+{
+       int xstp = ctrl2 & RTC_CTL2_BIT_XST;
+       /* XSTP bit has different polarity on RX-8025 vs RX-8035.
+        * RX-8025: 0 == oscillator stopped
+        * RX-8035: 1 == oscillator stopped
+        */
+
+       if (model == model_rx_8025)
+               xstp = !xstp;
+
+       return xstp;
+}
+
 /*
  * Get the current time from the RTC
  */
@@ -101,8 +120,7 @@ static int rx8025_rtc_get(struct udevice *dev, struct rtc_time *tmp)
                printf("RTC: voltage drop detected\n");
                rel = -1;
        }
-
-       if (!(ctl2 & RTC_CTL2_BIT_XST)) {
+       if (rx8025_is_osc_stopped(dev->driver_data, ctl2)) {
                printf("RTC: oscillator stop detected\n");
                rel = -1;
        }
@@ -180,7 +198,11 @@ static int rx8025_rtc_reset(struct udevice *dev)
 
        ctl2 = rtc_read(RTC_CTL2_REG_ADDR);
        ctl2 &= ~(RTC_CTL2_BIT_PON | RTC_CTL2_BIT_VDET);
-       ctl2 |= RTC_CTL2_BIT_XST | RTC_CTL2_BIT_VDSL;
+
+       if (dev->driver_data == model_rx_8035)
+               ctl2 &= ~(RTC_CTL2_BIT_XST);
+       else
+               ctl2 |= RTC_CTL2_BIT_XST;
 
        return rtc_write(dev, RTC_CTL2_REG_ADDR, ctl2);
 }
@@ -223,11 +245,12 @@ static const struct rtc_ops rx8025_rtc_ops = {
 };
 
 static const struct udevice_id rx8025_rtc_ids[] = {
-       { .compatible = "epson,rx8025" },
+       { .compatible = "epson,rx8025", .data = model_rx_8025 },
+       { .compatible = "epson,rx8035", .data = model_rx_8035 },
        { }
 };
 
-U_BOOT_DRIVER(rx8010sj_rtc) = {
+U_BOOT_DRIVER(rx8025_rtc) = {
        .name     = "rx8025_rtc",
        .id           = UCLASS_RTC,
        .probe    = rx8025_probe,