Add TDO readout functionnality in CMD_CLK (dirtyjtag#77)

Woolfy025 · Dec 13, 2022 · b69bb88 · b69bb88
1 parent bef4f6e
commit b69bb88
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Showing 3 changed files with 49 additions and 20 deletions.
diff --git a/src/cmd.c b/src/cmd.c
@@ -40,8 +40,11 @@ enum CommandIdentifier {
 };
 
 enum CommandModifier {
+  // CMD_XFER
   NO_READ = 0x80,
-  EXTEND_LENGTH = 0x40
+  EXTEND_LENGTH = 0x40,
+  // CMD_CLK
+  READOUT = 0x80,
 };
 
 enum SignalIdentifier {
@@ -108,10 +111,11 @@ static void cmd_getsig(usbd_device *usbd_dev);
  *
  * CMD_CLK sends clock pulses with specific TMS and TDI state.
  *
+ * @param usbd_dev USB device
  * @param commands Command data
+ * @param readout Enable TDO readout
  */
-static void cmd_clk(const uint8_t *commands);
-
+ static void cmd_clk(usbd_device *usbd_dev, const uint8_t *commands, bool readout);
 
 uint8_t cmd_handle(usbd_device *usbd_dev, const usbd_transfer *transfer) {
   uint8_t *commands= (uint8_t*)transfer->buffer;
@@ -143,8 +147,12 @@ uint8_t cmd_handle(usbd_device *usbd_dev, const usbd_transfer *transfer) {
       break;
 
     case CMD_CLK:
-      cmd_clk(commands);
-      commands += 2;
+      cmd_clk(usbd_dev, commands, !!(*commands & READOUT));
+      if (*commands & READOUT) {
+        return 0;
+      } else {
+        commands += 2;
+      }
       break;
 
     default:
@@ -231,11 +239,15 @@ static void cmd_getsig(usbd_device *usbd_dev) {
   usb_send(usbd_dev, &signal_status, 1);
 }
 
-static void cmd_clk(const uint8_t *commands) {
+static void cmd_clk(usbd_device *usbd_dev, const uint8_t *commands, bool readout) {
   uint8_t signals, clk_pulses;
 
   signals = commands[1];
   clk_pulses = commands[2];
 
-  jtag_strobe(clk_pulses, signals & SIG_TMS, signals & SIG_TDI);
+  uint8_t readout_val = jtag_strobe(clk_pulses, signals & SIG_TMS, signals & SIG_TDI);
+
+  if (readout) {
+    usb_send(usbd_dev, &readout_val, 1);
+  }
 }
diff --git a/src/jtag.c b/src/jtag.c
@@ -341,27 +341,34 @@ void jtag_transfer_internal(uint16_t length, const uint8_t *in, uint8_t *out) {
 
 }
 
-void jtag_strobe(uint8_t pulses, bool tms, bool tdi) {
-  /* Set TMS state */
+bool jtag_strobe(uint8_t pulses, bool tms, bool tdi) {
+  bool ret;
+
+  // Set initial TDI/TMS state
   jtag_set_tms(tms);
   jtag_set_tdi(tdi);
-  if (max_frequency)
-  {
-    while (pulses)
-    {
+
+  if (!pulses) {
+    ret = jtag_get_tdo();
+  } else if (max_frequency) {
+    pulses--;
+    while (pulses) {
+      pulses--;
       //double the writes to slow down the clock rate
       GPIO_BSRR(JTAG_PORT_TCK) = JTAG_PIN_TCK;
       GPIO_BSRR(JTAG_PORT_TCK) = JTAG_PIN_TCK;
       GPIO_BSRR(JTAG_PORT_TCK) = JTAG_PIN_TCK << 16;
       GPIO_BSRR(JTAG_PORT_TCK) = JTAG_PIN_TCK << 16;
-      pulses--;
     }
-  }
-  else
-  {
+    GPIO_BSRR(JTAG_PORT_TCK) = JTAG_PIN_TCK;
+    GPIO_BSRR(JTAG_PORT_TCK) = JTAG_PIN_TCK;
+    ret = jtag_get_tdo();
+    GPIO_BSRR(JTAG_PORT_TCK) = JTAG_PIN_TCK << 16;
+    GPIO_BSRR(JTAG_PORT_TCK) = JTAG_PIN_TCK << 16;
+  } else {
+    pulses--;
     timer_set_counter(TIM2,0);
-    while (pulses)
-    {
+    while (pulses) {
       TIM_SR(TIM2) = ~TIM_SR_UIF;
       GPIO_BSRR(JTAG_PORT_TCK) = JTAG_PIN_TCK;
       while (!(TIM_SR(TIM2) & TIM_SR_UIF));
@@ -370,7 +377,16 @@ void jtag_strobe(uint8_t pulses, bool tms, bool tdi) {
       pulses--;
       while (!(TIM_SR(TIM2) & TIM_SR_UIF));
     }
+    TIM_SR(TIM2) = ~TIM_SR_UIF;
+    GPIO_BSRR(JTAG_PORT_TCK) = JTAG_PIN_TCK;
+    while (!(TIM_SR(TIM2) & TIM_SR_UIF));
+    TIM_SR(TIM2) = ~TIM_SR_UIF;
+    ret = jtag_get_tdo();
+    GPIO_BSRR(JTAG_PORT_TCK) = JTAG_PIN_TCK << 16;
+    while (!(TIM_SR(TIM2) & TIM_SR_UIF));
   }
+
+  return ret;
 }
 
 #if USE_SPI1

diff --git a/src/jtag.h b/src/jtag.h
@@ -99,8 +99,9 @@ void jtag_transfer(uint16_t length, const uint8_t *in,
  * @param pulses Number of clock pulses
  * @param tms Logic state of TMS
  * @param tdi Logic state of TDI
+ * @return Last TDO state
  */
-void jtag_strobe(uint8_t pulses, bool tms, bool tdi);
+bool jtag_strobe(uint8_t pulses, bool tms, bool tdi);
 
 #define F_CPU 72000000UL
 #define HW_stlinkv2 0