iio: frequency: ad9172: implement sysref oneshot sequence

Support for performing oneshot sequence as laid out in
section "jesd204b serial data interface" and sync procedure
of datasheet rev C [1] for device. In addition to the already implemented
sysref_enable step, the other steps are also required for a sync to take
place.

Feature is here implemented for subclass 1 operation with jesd-fsm
enabled.

[1] https://www.analog.com/media/en/technical-documentation/data-sheets/ad9171.pdf
Signed-off-by: Tomas Melin <tomas.melin@vaisala.com>

Author: vai-tomme

drivers/iio/frequency/ad9172.c

@@ -67,6 +67,7 @@ struct ad9172_state {
 	u32 clock_output_config;
 	u32 scrambling;
 	u32 sysref_mode;
+	u32 sysref_err_win;
 	bool pll_bypass;
 	signal_type_t syncoutb_type;
 	signal_coupling_t sysref_coupling;
@@ -928,6 +929,9 @@ static int ad9172_parse_dt(struct spi_device *spi, struct ad9172_state *st)
 	if (of_property_read_u32(np, "adi,sysref-mode", &st->sysref_mode))
 		st->sysref_mode = SYSREF_CONT;
 
+	st->sysref_err_win = 0;
+	of_property_read_u32(np, "adi,sysref-error-window", &st->sysref_err_win);
+
 	/*Logic lane configuration*/
 	ret = of_property_read_u8_array(np,"adi,logic-lanes-mapping",
 				      st->logic_lanes, sizeof(st->logic_lanes));
@@ -1001,6 +1005,15 @@ static int ad9172_jesd204_link_enable(struct jesd204_dev *jdev,
 
 	ad917x_jesd_set_sysref_enable(&st->dac_h, !!st->jesd_subclass);
 
+	if (lnk->subclass == JESD204_SUBCLASS_1 &&
+	    st->sysref_mode == SYSREF_ONESHOT) {
+		ret = ad917x_jesd_oneshot_sync(&st->dac_h, st->sysref_err_win);
+		if (ret) {
+			dev_err(dev, "Failed to set oneshot sync (%d)\n", ret);
+			return ret;
+		}
+	}
+
 	/*Enable Link*/
 	ret = ad917x_jesd_enable_link(&st->dac_h, JESD_LINK_ALL,
 		reason == JESD204_STATE_OP_REASON_INIT);
@@ -1021,6 +1034,7 @@ static int ad9172_jesd204_link_running(struct jesd204_dev *jdev,
 	struct ad9172_state *st = priv->st;
 	unsigned long lane_rate_khz;
 	int ret;
+	bool done;
 
 	if (reason != JESD204_STATE_OP_REASON_INIT)
 		return JESD204_STATE_CHANGE_DONE;
@@ -1040,6 +1054,20 @@ static int ad9172_jesd204_link_running(struct jesd204_dev *jdev,
 		return ret;
 	}
 
+	if (lnk->subclass == JESD204_SUBCLASS_1 &&
+	    st->sysref_mode == SYSREF_ONESHOT) {
+		ret = ad917x_jesd_get_sync_rotation_done(&st->dac_h, &done);
+		if (ret) {
+			dev_err(dev, "Failed sync rotation read (%d)\n", ret);
+			return ret;
+		}
+
+		if (!done) {
+			dev_err(dev, "JESD204 sync rotation check failed\n");
+			return JESD204_STATE_CHANGE_ERROR;
+		}
+	}
+
 	return JESD204_STATE_CHANGE_DONE;
 }
 

drivers/iio/frequency/ad917x/AD917x.h

@@ -473,6 +473,27 @@ int ad917x_jesd_set_sysref_enable(ad917x_handle_t *h, uint8_t en);
  */
 int ad917x_jesd_get_sysref_enable(ad917x_handle_t *h, uint8_t *en);
 
+/**
+ * \brief Configure SYSREF for oneshot sync
+ *
+ * Configure SYSREF oneshot sequence to align LMFC on next SYSREF
+ * rising edge signal.
+ *
+ * \param h          Pointer to the AD917X device reference handle.
+ * \param err_window Error window in DAC clock cycles for SYSREF
+ *                   jitter.
+ */
+int ad917x_jesd_oneshot_sync(ad917x_handle_t *h, u8 err_window);
+
+/**
+ * \brief Check if sync rotation has happened
+ *
+ * Checks if SYSREF to LMFC synchronization logic has completed.
+ *
+ * \param h     Pointer to the AD917X device reference handle.
+ * \param *done Return value indicating if rotation has completed.
+ */
+int ad917x_jesd_get_sync_rotation_done(ad917x_handle_t *h, bool *done);
 
 /**
  * \brief Set the LMFC Delay and Variance for the JESD Links

drivers/iio/frequency/ad917x/ad917x_jesd_api.c

@@ -243,6 +243,51 @@ int ad917x_jesd_get_cfg_param(ad917x_handle_t *h,
 	return API_ERROR_OK;
 }
 
+int ad917x_jesd_oneshot_sync(ad917x_handle_t *h, u8 err_window)
+{
+	int err;
+	u8 mode;
+
+	if (!h)
+		return API_ERROR_INVALID_HANDLE_PTR;
+
+	err = ad917x_register_write(h, AD917X_SYSREF_ERR_WINDOW_REG,
+				    AD917X_SYSREF_ERR_WIN(err_window));
+	if (err)
+		return err;
+
+	err = ad917x_register_read(h, AD917X_SYSREF_MODE_REG, &mode);
+	if (err)
+		return err;
+
+	if (mode & AD917X_SYSREF_MODE_ONESHOT) {
+		err = ad917x_register_write(h, AD917X_SYSREF_MODE_REG,
+					    mode & ~AD917X_SYSREF_MODE_ONESHOT);
+		if (err)
+			return err;
+	}
+
+	return ad917x_register_write(h, AD917X_SYSREF_MODE_REG,
+				     mode | AD917X_SYSREF_MODE_ONESHOT);
+}
+
+int ad917x_jesd_get_sync_rotation_done(ad917x_handle_t *h, bool *done)
+{
+	int err;
+	u8 mode;
+
+	if (!h)
+		return API_ERROR_INVALID_HANDLE_PTR;
+
+	err = ad917x_register_read(h, AD917X_SYSREF_MODE_REG, &mode);
+	if (err)
+		return err;
+
+	*done = (mode & AD917X_SYNC_ROTATION_DONE);
+
+	return 0;
+}
+
 int ad917x_jesd_set_sysref_enable(ad917x_handle_t *h, uint8_t en)
 {
 	int err;

drivers/iio/frequency/ad917x/ad917x_reg.h

@@ -47,6 +47,14 @@ int ad917x_register_read_block(ad917x_handle_t *h,
 #define AD917X_MAINDAC_PAGE_0         BIT(6)
 #define AD917X_MAINDAC_PAGE_1         BIT(7)
 
+#define AD917X_SYSREF_ERR_WINDOW_REG  0x039
+#define AD917X_SYSREF_ERR_WIN(x)      (((x) & 0x7F) << 0)
+
+#define AD917X_SYSREF_MODE_REG        0x03A
+#define AD917X_SYNC_ROTATION_DONE     BIT(4)
+#define AD917X_SYSREF_MODE_ONESHOT    BIT(1)
+#define AD917X_SYSREF_MODE_CONTINUOUS BIT(0)
+
 #define AD917X_SYSREF_ROTATION_REG    0x03B
 #define AD917X_SYNC_LOGIC_EN          BIT(7)
 #define AD917X_SYNC_RSV_EN            BIT(6)