rtc: rx8025: implement RX-8035 support

The RX-8035 is a newer RTC from EPSON that is very
similar to the RX-8025.

The key difference is in the oscillation stop (XSTP)
bit which is inverted on the RX-8035.

Signed-off-by: Mathew McBride <matt@traverse.com.au>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Link: https://lore.kernel.org/r/20210709044518.28769-2-matt@traverse.com.au

diff --git a/drivers/rtc/rtc-rx8025.c b/drivers/rtc/rtc-rx8025.c
index c914091..d38aaf0 100644 (file)
--- a/drivers/rtc/rtc-rx8025.c
+++ b/drivers/rtc/rtc-rx8025.c
@@ -60,14 +60,23 @@
 #define RX8025_ADJ_DATA_MAX    62
 #define RX8025_ADJ_DATA_MIN    -62
 
+enum rx_model {
+       model_rx_unknown,
+       model_rx_8025,
+       model_rx_8035,
+       model_last
+};
+
 static const struct i2c_device_id rx8025_id[] = {
-       { "rx8025", 0 },
+       { "rx8025", model_rx_8025 },
+       { "rx8035", model_rx_8035 },
        { }
 };
 MODULE_DEVICE_TABLE(i2c, rx8025_id);
 
 struct rx8025_data {
        struct rtc_device *rtc;
+       enum rx_model model;
        u8 ctrl1;
 };
 
@@ -100,10 +109,26 @@ static s32 rx8025_write_regs(const struct i2c_client *client,
                                              length, values);
 }
 
+static int rx8025_is_osc_stopped(enum rx_model model, int ctrl2)
+{
+       int xstp = ctrl2 & RX8025_BIT_CTRL2_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;
+}
+
 static int rx8025_check_validity(struct device *dev)
 {
        struct i2c_client *client = to_i2c_client(dev);
+       struct rx8025_data *drvdata = dev_get_drvdata(dev);
        int ctrl2;
+       int xstp;
 
        ctrl2 = rx8025_read_reg(client, RX8025_REG_CTRL2);
        if (ctrl2 < 0)
@@ -117,7 +142,8 @@ static int rx8025_check_validity(struct device *dev)
                return -EINVAL;
        }
 
-       if (!(ctrl2 & RX8025_BIT_CTRL2_XST)) {
+       xstp = rx8025_is_osc_stopped(drvdata->model, ctrl2);
+       if (xstp) {
                dev_warn(dev, "crystal stopped, date is invalid\n");
                return -EINVAL;
        }
@@ -127,6 +153,7 @@ static int rx8025_check_validity(struct device *dev)
 
 static int rx8025_reset_validity(struct i2c_client *client)
 {
+       struct rx8025_data *drvdata = i2c_get_clientdata(client);
        int ctrl2 = rx8025_read_reg(client, RX8025_REG_CTRL2);
 
        if (ctrl2 < 0)
@@ -134,22 +161,28 @@ static int rx8025_reset_validity(struct i2c_client *client)
 
        ctrl2 &= ~(RX8025_BIT_CTRL2_PON | RX8025_BIT_CTRL2_VDET);
 
+       if (drvdata->model == model_rx_8025)
+               ctrl2 |= RX8025_BIT_CTRL2_XST;
+       else
+               ctrl2 &= ~(RX8025_BIT_CTRL2_XST);
+
        return rx8025_write_reg(client, RX8025_REG_CTRL2,
-                               ctrl2 | RX8025_BIT_CTRL2_XST);
+                               ctrl2);
 }
 
 static irqreturn_t rx8025_handle_irq(int irq, void *dev_id)
 {
        struct i2c_client *client = dev_id;
        struct rx8025_data *rx8025 = i2c_get_clientdata(client);
-       int status;
+       int status, xstp;
 
        rtc_lock(rx8025->rtc);
        status = rx8025_read_reg(client, RX8025_REG_CTRL2);
        if (status < 0)
                goto out;
 
-       if (!(status & RX8025_BIT_CTRL2_XST))
+       xstp = rx8025_is_osc_stopped(rx8025->model, status);
+       if (xstp)
                dev_warn(&client->dev, "Oscillation stop was detected,"
                         "you may have to readjust the clock\n");
 
@@ -519,6 +552,9 @@ static int rx8025_probe(struct i2c_client *client,
 
        i2c_set_clientdata(client, rx8025);
 
+       if (id)
+               rx8025->model = id->driver_data;
+
        err = rx8025_init_client(client);
        if (err)
                return err;