From 6654e2be5e7a6ae3eb9d66174f965a0db19d1172 Mon Sep 17 00:00:00 2001
From: Marc Schink <dev@zapb.de>
Date: Wed, 10 Mar 2021 18:14:29 +0100
Subject: jtag: Add functions to set/clear the TCK signal

Signed-off-by: Marc Schink <dev@zapb.de>
---
 libjaylink/jtag.c       | 90 +++++++++++++++++++++++++++++++++++++++++++++++++
 libjaylink/libjaylink.h |  2 ++
 2 files changed, 92 insertions(+)

diff --git a/libjaylink/jtag.c b/libjaylink/jtag.c
index d51a7c6..d40517c 100644
--- a/libjaylink/jtag.c
+++ b/libjaylink/jtag.c
@@ -36,6 +36,8 @@
 #define CMD_JTAG_SET_TRST	0xdf
 #define CMD_JTAG_CLEAR_TMS	0xc9
 #define CMD_JTAG_SET_TMS	0xca
+#define CMD_JTAG_CLEAR_TCK	0xda
+#define CMD_JTAG_SET_TCK	0xdb
 
 /**
  * Error code indicating that there is not enough free memory on the device to
@@ -347,3 +349,91 @@ JAYLINK_API int jaylink_jtag_set_tms(struct jaylink_device_handle *devh)
 
 	return JAYLINK_OK;
 }
+
+/**
+ * Clear the JTAG test clock (TCK) signal.
+ *
+ * @param[in,out] devh Device handle.
+ *
+ * @retval JAYLINK_OK Success.
+ * @retval JAYLINK_ERR_ARG Invalid arguments.
+ * @retval JAYLINK_ERR_TIMEOUT A timeout occurred.
+ * @retval JAYLINK_ERR_IO Input/output error.
+ * @retval JAYLINK_ERR Other error conditions.
+ *
+ * @since 0.3.0
+ */
+JAYLINK_API int jaylink_jtag_clear_tck(struct jaylink_device_handle *devh)
+{
+	int ret;
+	struct jaylink_context *ctx;
+	uint8_t buf[1];
+
+	if (!devh)
+		return JAYLINK_ERR_ARG;
+
+	ctx = devh->dev->ctx;
+	ret = transport_start_write(devh, 1, true);
+
+	if (ret != JAYLINK_OK) {
+		log_err(ctx, "transport_start_write() failed: %s",
+			jaylink_strerror(ret));
+		return ret;
+	}
+
+	buf[0] = CMD_JTAG_CLEAR_TCK;
+
+	ret = transport_write(devh, buf, 1);
+
+	if (ret != JAYLINK_OK) {
+		log_err(ctx, "transport_write() failed: %s",
+			jaylink_strerror(ret));
+		return ret;
+	}
+
+	return JAYLINK_OK;
+}
+
+/**
+ * Set the JTAG test clock (TCK) signal.
+ *
+ * @param[in,out] devh Device handle.
+ *
+ * @retval JAYLINK_OK Success.
+ * @retval JAYLINK_ERR_ARG Invalid arguments.
+ * @retval JAYLINK_ERR_TIMEOUT A timeout occurred.
+ * @retval JAYLINK_ERR_IO Input/output error.
+ * @retval JAYLINK_ERR Other error conditions.
+ *
+ * @since 0.3.0
+ */
+JAYLINK_API int jaylink_jtag_set_tck(struct jaylink_device_handle *devh)
+{
+	int ret;
+	struct jaylink_context *ctx;
+	uint8_t buf[1];
+
+	if (!devh)
+		return JAYLINK_ERR_ARG;
+
+	ctx = devh->dev->ctx;
+	ret = transport_start_write(devh, 1, true);
+
+	if (ret != JAYLINK_OK) {
+		log_err(ctx, "transport_start_write() failed: %s",
+			jaylink_strerror(ret));
+		return ret;
+	}
+
+	buf[0] = CMD_JTAG_SET_TCK;
+
+	ret = transport_write(devh, buf, 1);
+
+	if (ret != JAYLINK_OK) {
+		log_err(ctx, "transport_write() failed: %s",
+			jaylink_strerror(ret));
+		return ret;
+	}
+
+	return JAYLINK_OK;
+}
diff --git a/libjaylink/libjaylink.h b/libjaylink/libjaylink.h
index 3553aff..23f759b 100644
--- a/libjaylink/libjaylink.h
+++ b/libjaylink/libjaylink.h
@@ -577,6 +577,8 @@ JAYLINK_API int jaylink_jtag_clear_trst(struct jaylink_device_handle *devh);
 JAYLINK_API int jaylink_jtag_set_trst(struct jaylink_device_handle *devh);
 JAYLINK_API int jaylink_jtag_clear_tms(struct jaylink_device_handle *devh);
 JAYLINK_API int jaylink_jtag_set_tms(struct jaylink_device_handle *devh);
+JAYLINK_API int jaylink_jtag_clear_tck(struct jaylink_device_handle *devh);
+JAYLINK_API int jaylink_jtag_set_tck(struct jaylink_device_handle *devh);
 
 /*--- log.c -----------------------------------------------------------------*/
 
-- 
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