swim: abstract the transport in stm8 target

SWIM is implemented by (ab)using the HLA API. This was acceptable
when OpenOCD code did not provided a clear separation between
transports and related APIs. Still today SWIM in OpenOCD is only
supported by STLink, so the decision to re-use the HLA API was the
simpler way to implement it.
After commit efd1d64222 ("adapter: switch from struct
jtag_interface to adapter_driver") the transports API are better
split and SWIM can be implemented as a separate set of API. This
would open the possibility to extend OpenOCD for other adapters
that provide SWIM, e.g. versaloon, or through SPI emulation [1].

Introduce a new set of files swim.[ch] to handle the SWIM API.
Beside the API that almost match the transport low-level data
communication (system_reset, read_mem, write_mem), add a further
API reconnect. Today, inside HLA STLink code, the reconnect is
implemented by hacking the HLA API state(). Please notice that
due to this hack the return type is incorrect; stlink_usb_state()
returns ERROR_OK in SWIM mode, while its return type is enum
target_state. Ignore the type mismatch and still call the HLA API
state in the new SWIM API reconnect. Further commit will fix it.

[1] http://kuku.eu.org/?projects/stm8spi/stm8spi

Change-Id: I52018e1e2200cbd41af8e5031f7b35dc761b61d6
Signed-off-by: Antonio Borneo <borneo.antonio@gmail.com>
Reviewed-on: http://openocd.zylin.com/5528
Tested-by: jenkins

src/jtag/Makefile.am

@@ -56,6 +56,7 @@ endif
 	%D%/interface.c \
 	%D%/interfaces.c \
 	%D%/tcl.c \
+	%D%/swim.c \
 	%D%/commands.h \
 	%D%/driver.h \
 	%D%/interface.h \
@@ -65,6 +66,7 @@ endif
 	%D%/minidriver/minidriver_imp.h \
 	%D%/minidummy/jtag_minidriver.h \
 	%D%/swd.h \
+	%D%/swim.h \
 	%D%/tcl.h \
 	$(JTAG_SRCS)
 

src/jtag/swim.c

@@ -0,0 +1,51 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+
+/*
+ * Copyright (C) 2020 by Antonio Borneo <borneo.antonio@gmail.com
+ *
+ * SWIM (Single Wire Interface Module) is a low-pin-count debug protocol
+ * used by STMicroelectronics MCU family STM8 and documented in UM470
+ * https://www.st.com/resource/en/user_manual/cd00173911.pdf
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#include "interface.h"
+#include "swim.h"
+#include "jtag/hla/hla_transport.h"
+#include "jtag/hla/hla_interface.h"
+#include "jtag/hla/hla_layout.h"
+
+extern struct adapter_driver *adapter_driver;
+
+int swim_system_reset(void)
+{
+	assert(adapter_driver->hla_if);
+
+	return adapter_driver->hla_if->layout->api->reset(adapter_driver->hla_if->handle);
+}
+
+int swim_read_mem(uint32_t addr, uint32_t size, uint32_t count,
+				  uint8_t *buffer)
+{
+	assert(adapter_driver->hla_if);
+
+	return adapter_driver->hla_if->layout->api->read_mem(adapter_driver->hla_if->handle, addr, size, count, buffer);
+}
+
+int swim_write_mem(uint32_t addr, uint32_t size, uint32_t count,
+				   const uint8_t *buffer)
+{
+	assert(adapter_driver->hla_if);
+
+	return adapter_driver->hla_if->layout->api->write_mem(adapter_driver->hla_if->handle, addr, size, count, buffer);
+}
+
+int swim_reconnect(void)
+{
+	assert(adapter_driver->hla_if);
+
+	return adapter_driver->hla_if->layout->api->state(adapter_driver->hla_if->handle);
+}

src/jtag/swim.h

@@ -0,0 +1,65 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+
+/*
+ * Copyright (C) 2020 by Antonio Borneo <borneo.antonio@gmail.com
+ */
+
+/**
+ * @file
+ * This file implements support for STMicroelectronics debug protocol SWIM
+ * (Single Wire Interface Module).
+ */
+
+#ifndef OPENOCD_JTAG_SWIM_H
+#define OPENOCD_JTAG_SWIM_H
+
+struct swim_driver {
+	/**
+	 * Send SRST (system reset) command to target.
+	 *
+	 * @return ERROR_OK on success, else a fault code.
+	 */
+	int (*srst)(void);
+
+	/**
+	 * Read target memory through ROTF (read on-the-fly) command.
+	 *
+	 * @param addr Start address to read data from target memory.
+	 * @param size Size in bytes of data units, 1, 2 or 4.
+	 * @param count Number of units (size units, not bytes) to read.
+	 * @param buffer Data buffer to receive data.
+	 * @return ERROR_OK on success, else a fault code.
+	 */
+	int (*read_mem)(uint32_t addr, uint32_t size, uint32_t count,
+					uint8_t *buffer);
+
+	/**
+	 * Write target memory through WOTF (write on-the-fly) command.
+	 *
+	 * @param addr Start address to write data to target memory.
+	 * @param size Size in bytes of data units, 1, 2 or 4.
+	 * @param count Number of units (size units, not bytes) to write.
+	 * @param buffer Data buffer to write.
+	 * @return ERROR_OK on success, else a fault code.
+	 */
+	int (*write_mem)(uint32_t addr, uint32_t size, uint32_t count,
+					 const uint8_t *buffer);
+
+	/**
+	 * Reconnect to the target.
+	 * Should be reworked to be more generic and not linked to current
+	 * implementation in stlink driver.
+	 *
+	 * @return ERROR_OK on success, else a fault code.
+	 */
+	int (*reconnect)(void);
+};
+
+int swim_system_reset(void);
+int swim_read_mem(uint32_t addr, uint32_t size, uint32_t count,
+				  uint8_t *buffer);
+int swim_write_mem(uint32_t addr, uint32_t size, uint32_t count,
+				   const uint8_t *buffer);
+int swim_reconnect(void);
+
+#endif /* OPENOCD_JTAG_SWIM_H */

src/target/stm8.c

@@ -27,9 +27,7 @@
 #include "hello.h"
 #include "jtag/interface.h"
 #include "jtag/jtag.h"
-#include "jtag/hla/hla_transport.h"
+#include "jtag/swim.h"
-#include "jtag/hla/hla_interface.h"
-#include "jtag/hla/hla_layout.h"
 #include "register.h"
 #include "breakpoints.h"
 #include "algorithm.h"
@@ -180,68 +178,31 @@ struct stm8_comparator {
 	enum hw_break_type type;
 };
 
-static inline struct hl_interface_s *target_to_adapter(struct target *target)
-{
-	return target->tap->priv;
-}
-
 static int stm8_adapter_read_memory(struct target *target,
 		uint32_t addr, int size, int count, void *buf)
 {
-	int ret;
+	return swim_read_mem(addr, size, count, buf);
-	struct hl_interface_s *adapter = target_to_adapter(target);
-
-	ret = adapter->layout->api->read_mem(adapter->handle,
-		addr, size, count, buf);
-	if (ret != ERROR_OK)
-		return ret;
-	return ERROR_OK;
 }
 
 static int stm8_adapter_write_memory(struct target *target,
 		uint32_t addr, int size, int count, const void *buf)
 {
-	int ret;
+	return swim_write_mem(addr, size, count, buf);
-	struct hl_interface_s *adapter = target_to_adapter(target);
-
-	ret = adapter->layout->api->write_mem(adapter->handle,
-		addr, size, count, buf);
-	if (ret != ERROR_OK)
-		return ret;
-	return ERROR_OK;
 }
 
 static int stm8_write_u8(struct target *target,
 		uint32_t addr, uint8_t val)
 {
-	int ret;
 	uint8_t buf[1];
-	struct hl_interface_s *adapter = target_to_adapter(target);
 
 	buf[0] = val;
-	ret =  adapter->layout->api->write_mem(adapter->handle, addr, 1, 1, buf);
+	return swim_write_mem(addr, 1, 1, buf);
-	if (ret != ERROR_OK)
-		return ret;
-	return ERROR_OK;
 }
 
 static int stm8_read_u8(struct target *target,
 		uint32_t addr, uint8_t *val)
 {
-	int ret;
+	return swim_read_mem(addr, 1, 1, val);
-	struct hl_interface_s *adapter = target_to_adapter(target);
-
-	ret =  adapter->layout->api->read_mem(adapter->handle, addr, 1, 1, val);
-	if (ret != ERROR_OK)
-		return ret;
-	return ERROR_OK;
-}
-
-static int stm8_set_speed(struct target *target, int speed)
-{
-	struct hl_interface_s *adapter = target_to_adapter(target);
-	adapter->layout->api->speed(adapter->handle, speed, 0);
-	return ERROR_OK;
 }
 
 /*
@@ -924,7 +885,6 @@ static int stm8_halt(struct target *target)
 static int stm8_reset_assert(struct target *target)
 {
 	int res = ERROR_OK;
-	struct hl_interface_s *adapter = target_to_adapter(target);
 	struct stm8_common *stm8 = target_to_stm8(target);
 	bool use_srst_fallback = true;
 
@@ -942,7 +902,7 @@ static int stm8_reset_assert(struct target *target)
 
 	if (use_srst_fallback) {
 		LOG_DEBUG("Hardware srst not supported, falling back to swim reset");
-		res = adapter->layout->api->reset(adapter->handle);
+		res = swim_system_reset();
 		if (res != ERROR_OK)
 			return res;
 	}
@@ -1696,7 +1656,7 @@ static int stm8_examine(struct target *target)
 	uint8_t csr1, csr2;
 	/* get pointers to arch-specific information */
 	struct stm8_common *stm8 = target_to_stm8(target);
-	struct hl_interface_s *adapter = target_to_adapter(target);
+	enum reset_types jtag_reset_config = jtag_get_reset_config();
 
 	if (!target_was_examined(target)) {
 		if (!stm8->swim_configured) {
@@ -1710,20 +1670,23 @@ static int stm8_examine(struct target *target)
 			retval = stm8_write_u8(target, SWIM_CSR, SAFE_MASK + SWIM_DM + HS);
 			if (retval != ERROR_OK)
 				return retval;
-			retval = stm8_set_speed(target, 1);
+			jtag_config_khz(1);
-			if (retval == ERROR_OK)
+			stm8->swim_configured = true;
-				stm8->swim_configured = true;
 			/*
 				Now is the time to deassert reset if connect_under_reset.
 				Releasing reset line will cause the option bytes to load.
 				The core will still be stalled.
 			*/
-			if (adapter->param.connect_under_reset)
+			if (jtag_reset_config & RESET_CNCT_UNDER_SRST) {
-				stm8_reset_deassert(target);
+				if (jtag_reset_config & RESET_SRST_NO_GATING)
+					stm8_reset_deassert(target);
+				else
+					LOG_WARNING("\'srst_nogate\' reset_config option is required");
+			}
 		} else {
 			LOG_INFO("trying to reconnect");
 
-			retval = adapter->layout->api->state(adapter->handle);
+			retval = swim_reconnect();
 			if (retval != ERROR_OK) {
 				LOG_ERROR("reconnect failed");
 				return ERROR_FAIL;