bitbang: split jtag and swd operations

The split in OpenOCD between SWD and JTAG has been already fully
implemented. The bitbang driver still keeps a single API write()
to drive the output lines.

Introduce a new SWD specific API swd_write().
Move the existing SWD bitbang drivers to the new API by extracting
the available conditional implementation.
Cleanup some function prototype.
Remove the now unused global swd_mode, handled implicitly.
Rename bitbang_exchange() as bitbang_swd_exchange() to track its
scope for SWD only.

Change-Id: Ie53080b941cb1ac7a34a1f80bad8bee4e304454d
Signed-off-by: Antonio Borneo <borneo.antonio@gmail.com>
Reviewed-on: http://openocd.zylin.com/5555
Tested-by: jenkins

5 files changed, 33 insertions, 42 deletions

diff --git a/src/jtag/drivers/bcm2835gpio.c b/src/jtag/drivers/bcm2835gpio.c
index f547d93a4..77ae5668f 100644
--- a/src/jtag/drivers/bcm2835gpio.c
+++ b/src/jtag/drivers/bcm2835gpio.c
@@ -54,6 +54,7 @@ static int bcm2835gpio_write(int tck, int tms, int tdi);
 
 static int bcm2835_swdio_read(void);
 static void bcm2835_swdio_drive(bool is_output);
+static int bcm2835gpio_swd_write(int swclk, int swdio);
 
 static int bcm2835gpio_init(void);
 static int bcm2835gpio_quit(void);
@@ -63,6 +64,7 @@ static struct bitbang_interface bcm2835gpio_bitbang = {
 	.write = bcm2835gpio_write,
 	.swdio_read = bcm2835_swdio_read,
 	.swdio_drive = bcm2835_swdio_drive,
+	.swd_write = bcm2835gpio_swd_write,
 	.blink = NULL
 };
 
@@ -108,10 +110,10 @@ static int bcm2835gpio_write(int tck, int tms, int tdi)
 	return ERROR_OK;
 }
 
-static int bcm2835gpio_swd_write(int tck, int tms, int tdi)
+static int bcm2835gpio_swd_write(int swclk, int swdio)
 {
-	uint32_t set = tck<<swclk_gpio | tdi<<swdio_gpio;
-	uint32_t clear = !tck<<swclk_gpio | !tdi<<swdio_gpio;
+	uint32_t set = swclk << swclk_gpio | swdio << swdio_gpio;
+	uint32_t clear = !swclk << swclk_gpio | !swdio << swdio_gpio;
 
 	GPIO_SET = set;
 	GPIO_CLR = clear;
@@ -533,10 +535,6 @@ static int bcm2835gpio_init(void)
 		  "tdo %d trst %d srst %d", tck_gpio_mode, tms_gpio_mode,
 		  tdi_gpio_mode, tdo_gpio_mode, trst_gpio_mode, srst_gpio_mode);
 
-	if (swd_mode) {
-		bcm2835gpio_bitbang.write = bcm2835gpio_swd_write;
-	}
-
 	return ERROR_OK;
 }
 
diff --git a/src/jtag/drivers/bitbang.c b/src/jtag/drivers/bitbang.c
index e5df3cf40..4417e1258 100644
--- a/src/jtag/drivers/bitbang.c
+++ b/src/jtag/drivers/bitbang.c
@@ -382,28 +382,24 @@ int bitbang_execute_queue(void)
 	return retval;
 }
 
-
-bool swd_mode;
 static int queued_retval;
 
 static int bitbang_swd_init(void)
 {
 	LOG_DEBUG("bitbang_swd_init");
-	swd_mode = true;
 	return ERROR_OK;
 }
 
-static void bitbang_exchange(bool rnw, uint8_t buf[], unsigned int offset, unsigned int bit_cnt)
+static void bitbang_swd_exchange(bool rnw, uint8_t buf[], unsigned int offset, unsigned int bit_cnt)
 {
-	LOG_DEBUG("bitbang_exchange");
-	int tdi;
+	LOG_DEBUG("bitbang_swd_exchange");
 
 	for (unsigned int i = offset; i < bit_cnt + offset; i++) {
 		int bytec = i/8;
 		int bcval = 1 << (i % 8);
-		tdi = !rnw && (buf[bytec] & bcval);
+		int swdio = !rnw && (buf[bytec] & bcval);
 
-		bitbang_interface->write(0, 0, tdi);
+		bitbang_interface->swd_write(0, swdio);
 
 		if (rnw && buf) {
 			if (bitbang_interface->swdio_read())
@@ -412,7 +408,7 @@ static void bitbang_exchange(bool rnw, uint8_t buf[], unsigned int offset, unsig
 				buf[bytec] &= ~bcval;
 		}
 
-		bitbang_interface->write(1, 0, tdi);
+		bitbang_interface->swd_write(1, swdio);
 	}
 }
 
@@ -423,15 +419,15 @@ static int bitbang_swd_switch_seq(enum swd_special_seq seq)
 	switch (seq) {
 	case LINE_RESET:
 		LOG_DEBUG("SWD line reset");
-		bitbang_exchange(false, (uint8_t *)swd_seq_line_reset, 0, swd_seq_line_reset_len);
+		bitbang_swd_exchange(false, (uint8_t *)swd_seq_line_reset, 0, swd_seq_line_reset_len);
 		break;
 	case JTAG_TO_SWD:
 		LOG_DEBUG("JTAG-to-SWD");
-		bitbang_exchange(false, (uint8_t *)swd_seq_jtag_to_swd, 0, swd_seq_jtag_to_swd_len);
+		bitbang_swd_exchange(false, (uint8_t *)swd_seq_jtag_to_swd, 0, swd_seq_jtag_to_swd_len);
 		break;
 	case SWD_TO_JTAG:
 		LOG_DEBUG("SWD-to-JTAG");
-		bitbang_exchange(false, (uint8_t *)swd_seq_swd_to_jtag, 0, swd_seq_swd_to_jtag_len);
+		bitbang_swd_exchange(false, (uint8_t *)swd_seq_swd_to_jtag, 0, swd_seq_swd_to_jtag_len);
 		break;
 	default:
 		LOG_ERROR("Sequence %d not supported", seq);
@@ -461,10 +457,10 @@ static void bitbang_swd_read_reg(uint8_t cmd, uint32_t *value, uint32_t ap_delay
 		uint8_t trn_ack_data_parity_trn[DIV_ROUND_UP(4 + 3 + 32 + 1 + 4, 8)];
 
 		cmd |= SWD_CMD_START | (1 << 7);
-		bitbang_exchange(false, &cmd, 0, 8);
+		bitbang_swd_exchange(false, &cmd, 0, 8);
 
 		bitbang_interface->swdio_drive(false);
-		bitbang_exchange(true, trn_ack_data_parity_trn, 0, 1 + 3 + 32 + 1 + 1);
+		bitbang_swd_exchange(true, trn_ack_data_parity_trn, 0, 1 + 3 + 32 + 1 + 1);
 		bitbang_interface->swdio_drive(true);
 
 		int ack = buf_get_u32(trn_ack_data_parity_trn, 1, 3);
@@ -488,7 +484,7 @@ static void bitbang_swd_read_reg(uint8_t cmd, uint32_t *value, uint32_t ap_delay
 			if (value)
 				*value = data;
 			if (cmd & SWD_CMD_APnDP)
-				bitbang_exchange(true, NULL, 0, ap_delay_clk);
+				bitbang_swd_exchange(true, NULL, 0, ap_delay_clk);
 			return;
 		 case SWD_ACK_WAIT:
 			LOG_DEBUG("SWD_ACK_WAIT");
@@ -522,12 +518,12 @@ static void bitbang_swd_write_reg(uint8_t cmd, uint32_t value, uint32_t ap_delay
 		buf_set_u32(trn_ack_data_parity_trn, 1 + 3 + 1 + 32, 1, parity_u32(value));
 
 		cmd |= SWD_CMD_START | (1 << 7);
-		bitbang_exchange(false, &cmd, 0, 8);
+		bitbang_swd_exchange(false, &cmd, 0, 8);
 
 		bitbang_interface->swdio_drive(false);
-		bitbang_exchange(true, trn_ack_data_parity_trn, 0, 1 + 3 + 1);
+		bitbang_swd_exchange(true, trn_ack_data_parity_trn, 0, 1 + 3 + 1);
 		bitbang_interface->swdio_drive(true);
-		bitbang_exchange(false, trn_ack_data_parity_trn, 1 + 3 + 1, 32 + 1);
+		bitbang_swd_exchange(false, trn_ack_data_parity_trn, 1 + 3 + 1, 32 + 1);
 
 		int ack = buf_get_u32(trn_ack_data_parity_trn, 1, 3);
 		LOG_DEBUG("%s %s %s reg %X = %08"PRIx32,
@@ -540,7 +536,7 @@ static void bitbang_swd_write_reg(uint8_t cmd, uint32_t value, uint32_t ap_delay
 		switch (ack) {
 		 case SWD_ACK_OK:
 			if (cmd & SWD_CMD_APnDP)
-				bitbang_exchange(true, NULL, 0, ap_delay_clk);
+				bitbang_swd_exchange(true, NULL, 0, ap_delay_clk);
 			return;
 		 case SWD_ACK_WAIT:
 			LOG_DEBUG("SWD_ACK_WAIT");
@@ -563,7 +559,7 @@ static int bitbang_swd_run_queue(void)
 	LOG_DEBUG("bitbang_swd_run_queue");
 	/* A transaction must be followed by another transaction or at least 8 idle cycles to
 	 * ensure that data is clocked through the AP. */
-	bitbang_exchange(true, NULL, 0, 8);
+	bitbang_swd_exchange(true, NULL, 0, 8);
 
 	int retval = queued_retval;
 	queued_retval = ERROR_OK;
diff --git a/src/jtag/drivers/bitbang.h b/src/jtag/drivers/bitbang.h
index 52dfbda30..bc2c506bc 100644
--- a/src/jtag/drivers/bitbang.h
+++ b/src/jtag/drivers/bitbang.h
@@ -62,12 +62,13 @@ struct bitbang_interface {
 
 	/** Set direction of SWDIO. */
 	void (*swdio_drive)(bool on);
+
+	/** Set SWCLK and SWDIO to the given value. */
+	int (*swd_write)(int swclk, int swdio);
 };
 
 extern const struct swd_driver bitbang_swd;
 
-extern bool swd_mode;
-
 int bitbang_execute_queue(void);
 
 extern struct bitbang_interface *bitbang_interface;
diff --git a/src/jtag/drivers/imx_gpio.c b/src/jtag/drivers/imx_gpio.c
index debddedfe..b96b433f7 100644
--- a/src/jtag/drivers/imx_gpio.c
+++ b/src/jtag/drivers/imx_gpio.c
@@ -87,6 +87,7 @@ static int imx_gpio_write(int tck, int tms, int tdi);
 
 static int imx_gpio_swdio_read(void);
 static void imx_gpio_swdio_drive(bool is_output);
+static int imx_gpio_swd_write(int swclk, int swdio);
 
 static int imx_gpio_init(void);
 static int imx_gpio_quit(void);
@@ -96,6 +97,7 @@ static struct bitbang_interface imx_gpio_bitbang = {
 	.write = imx_gpio_write,
 	.swdio_read = imx_gpio_swdio_read,
 	.swdio_drive = imx_gpio_swdio_drive,
+	.swd_write = imx_gpio_swd_write,
 	.blink = NULL
 };
 
@@ -143,10 +145,10 @@ static int imx_gpio_write(int tck, int tms, int tdi)
 	return ERROR_OK;
 }
 
-static int imx_gpio_swd_write(int tck, int tms, int tdi)
+static int imx_gpio_swd_write(int swclk, int swdio)
 {
-	tdi ? gpio_set(swdio_gpio) : gpio_clear(swdio_gpio);
-	tck ? gpio_set(swclk_gpio) : gpio_clear(swclk_gpio);
+	swdio ? gpio_set(swdio_gpio) : gpio_clear(swdio_gpio);
+	swclk ? gpio_set(swclk_gpio) : gpio_clear(swclk_gpio);
 
 	for (unsigned int i = 0; i < jtag_delay; i++)
 		asm volatile ("");
@@ -550,10 +552,6 @@ static int imx_gpio_init(void)
 		  "tdo %d trst %d srst %d", tck_gpio_mode, tms_gpio_mode,
 		  tdi_gpio_mode, tdo_gpio_mode, trst_gpio_mode, srst_gpio_mode);
 
-	if (swd_mode) {
-		imx_gpio_bitbang.write = imx_gpio_swd_write;
-	}
-
 	return ERROR_OK;
 }
 
diff --git a/src/jtag/drivers/sysfsgpio.c b/src/jtag/drivers/sysfsgpio.c
index f9470a47b..a58962098 100644
--- a/src/jtag/drivers/sysfsgpio.c
+++ b/src/jtag/drivers/sysfsgpio.c
@@ -230,7 +230,7 @@ static int sysfsgpio_swdio_read(void)
 	return buf[0] != '0';
 }
 
-static void sysfsgpio_swdio_write(int swclk, int swdio)
+static int sysfsgpio_swd_write(int swclk, int swdio)
 {
 	const char one[] = "1";
 	const char zero[] = "0";
@@ -255,6 +255,8 @@ static void sysfsgpio_swdio_write(int swclk, int swdio)
 	last_swdio = swdio;
 	last_swclk = swclk;
 	last_stored = true;
+
+	return ERROR_OK;
 }
 
 /*
@@ -287,11 +289,6 @@ static bb_value_t sysfsgpio_read(void)
  */
 static int sysfsgpio_write(int tck, int tms, int tdi)
 {
-	if (swd_mode) {
-		sysfsgpio_swdio_write(tck, tdi);
-		return ERROR_OK;
-	}
-
 	const char one[] = "1";
 	const char zero[] = "0";
 
@@ -572,6 +569,7 @@ static struct bitbang_interface sysfsgpio_bitbang = {
 	.write = sysfsgpio_write,
 	.swdio_read = sysfsgpio_swdio_read,
 	.swdio_drive = sysfsgpio_swdio_drive,
+	.swd_write = sysfsgpio_swd_write,
 	.blink = 0
 };