DJTAG2 protocol implementation

re-arraged the code in each jtag_transfer functions to open the timing window as much as possible.
Woolfy025 · Dec 13, 2022 · e71a6d6 · e71a6d6
1 parent 1920231
commit e71a6d6
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Showing 3 changed files with 54 additions and 27 deletions.
diff --git a/src/cmd.c b/src/cmd.c
@@ -20,6 +20,7 @@
 */
 
 #include <stdint.h>
+#include <stdbool.h>
 #include <string.h>
 #include <unicore-mx/usbd/usbd.h>
 #include <unicore-mx/stm32/gpio.h>
@@ -38,6 +39,11 @@ enum CommandIdentifier {
   CMD_CLK = 0x06
 };
 
+enum CommandModifier {
+  NO_READ = 0x80,
+  EXTEND_LENGTH = 0x40
+};
+
 enum SignalIdentifier {
   SIG_TCK = 1 << 1,
   SIG_TDI = 1 << 2,
@@ -77,7 +83,7 @@ static void cmd_freq(const uint8_t *commands);
  * @param usbd_dev USB device
  * @param commands Command data
  */
-static void cmd_xfer(usbd_device *usbd_dev, const uint8_t *commands);
+static void cmd_xfer(usbd_device *usbd_dev, const uint8_t *commands, bool extend_length, bool no_read);
 
 /**
  * @brief Handle CMD_SETSIG command
@@ -106,13 +112,12 @@ static void cmd_getsig(usbd_device *usbd_dev);
  */
 static void cmd_clk(const uint8_t *commands);
 
-uint8_t cmd_handle(usbd_device *usbd_dev, const usbd_transfer *transfer) {
-  uint8_t *commands;
 
-  commands = (uint8_t*)transfer->buffer;
+uint8_t cmd_handle(usbd_device *usbd_dev, const usbd_transfer *transfer) {
+  uint8_t *commands= (uint8_t*)transfer->buffer;
 
   while (*commands != CMD_STOP) {
-    switch (*commands) {
+    switch ((*commands)&0x0F) {
     case CMD_INFO:
       cmd_info(usbd_dev);
       break;
@@ -123,8 +128,8 @@ uint8_t cmd_handle(usbd_device *usbd_dev, const usbd_transfer *transfer) {
       break;
 
     case CMD_XFER:
-      cmd_xfer(usbd_dev, commands);
-      return 0;
+      cmd_xfer(usbd_dev, commands, *commands & EXTEND_LENGTH, *commands & NO_READ);
+      return !!(*commands & NO_READ);
       break;
 
     case CMD_SETSIG:
@@ -154,7 +159,7 @@ uint8_t cmd_handle(usbd_device *usbd_dev, const usbd_transfer *transfer) {
 }
 
 static void cmd_info(usbd_device *usbd_dev) {
-  char info_string[64] = "DJTAG1\n";
+  char info_string[64] = "DJTAG2\n";
 
   usb_send(usbd_dev, (uint8_t*)info_string, 64);
 }
@@ -163,22 +168,34 @@ static void cmd_freq(const uint8_t *commands) {
   jtag_set_frequency((commands[1] << 8) | commands[2]);
 }
 
-static void cmd_xfer(usbd_device *usbd_dev, const uint8_t *commands) {
-  uint8_t transferred_bits;
-  uint8_t output_buffer[32];
+static void cmd_xfer(usbd_device *usbd_dev, const uint8_t *commands, bool extend_length, bool no_read) {
+  uint16_t transferred_bits;
+  uint8_t output_buffer[64];
 
   /* Fill the output buffer with zeroes */
-  memset(output_buffer, 0, 32);
+  if (!no_read) {
+    memset(output_buffer, 0, sizeof(output_buffer));
+  }
 
   /* This is the number of transfered bits in one transfer command */
   transferred_bits = commands[1];
-
+  if (extend_length) {
+    transferred_bits += 256;
+    // Ensure we don't do over-read
+    if (transferred_bits > 62*8) {
+      return;
+    }
+  }
   jtag_transfer(transferred_bits, commands+2, output_buffer);
 
   /* Send the transfer response back to host */
-  usb_send(usbd_dev, output_buffer, 32);
+  if (!no_read) {
+    usb_send(usbd_dev, output_buffer, (transferred_bits + 7)/8);
+  }
 }
 
+
+
 static void cmd_setsig(const uint8_t *commands) {
   uint8_t signal_mask, signal_status;
 

diff --git a/src/jtag.c b/src/jtag.c
@@ -249,7 +249,7 @@ void jtag_set_srst(uint8_t value) {
 
 
 
-void jtag_transfer_internal(uint8_t length, const uint8_t *in, uint8_t *out) {
+void jtag_transfer_internal(uint16_t length, const uint8_t *in, uint8_t *out) {
   uint32_t xfer_length, xfer_i;
   const uint8_t *xfer_in;
   uint8_t *xfer_out;
@@ -265,13 +265,14 @@ void jtag_transfer_internal(uint8_t length, const uint8_t *in, uint8_t *out) {
     while (xfer_i < xfer_length)
     {
       uint8_t bitmask;
-
       bitmask = 0x80 >> (xfer_i%8) ;
 
       if (xfer_in[xfer_i/8] & bitmask) {
         GPIO_BSRR(JTAG_PORT_TDI) = JTAG_PIN_TDI;
+        GPIO_BSRR(JTAG_PORT_TDI) = JTAG_PIN_TDI;
       } else {
         GPIO_BSRR(JTAG_PORT_TDI) = JTAG_PIN_TDI << 16;
+        GPIO_BSRR(JTAG_PORT_TDI) = JTAG_PIN_TDI << 16;
       }
 
       GPIO_BSRR(JTAG_PORT_TCK) = JTAG_PIN_TCK;
@@ -280,19 +281,21 @@ void jtag_transfer_internal(uint8_t length, const uint8_t *in, uint8_t *out) {
         xfer_out[xfer_i/8] |= bitmask;
       }
 
-      GPIO_BSRR(JTAG_PORT_TCK) = JTAG_PIN_TCK << 16;
-
       xfer_i++;
+
+
+      GPIO_BSRR(JTAG_PORT_TCK) = JTAG_PIN_TCK << 16;
 
     }
   }
   else 
   {
     timer_set_counter(TIM2,0);
+    TIM_SR(TIM2) = ~TIM_SR_UIF;
+
     while (xfer_i < xfer_length)
     {
       uint8_t bitmask;
-      TIM_SR(TIM2) = ~TIM_SR_UIF;
 
       bitmask = 0x80 >> (xfer_i%8) ;
 
@@ -302,6 +305,9 @@ void jtag_transfer_internal(uint8_t length, const uint8_t *in, uint8_t *out) {
         GPIO_BSRR(JTAG_PORT_TDI) = JTAG_PIN_TDI << 16;
       }
 
+      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));
@@ -311,11 +317,13 @@ void jtag_transfer_internal(uint8_t length, const uint8_t *in, uint8_t *out) {
         xfer_out[xfer_i/8] |= bitmask;
       }
 
+      xfer_i++;
+
       GPIO_BSRR(JTAG_PORT_TCK) = JTAG_PIN_TCK << 16;
 
-      xfer_i++;
+
+
 
-      while (!(TIM_SR(TIM2) & TIM_SR_UIF));
 
     }
   }
@@ -330,8 +338,11 @@ void jtag_strobe(uint8_t pulses, bool tms, bool tdi) {
   {
     while (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--;
     }
   }
@@ -352,9 +363,9 @@ void jtag_strobe(uint8_t pulses, bool tms, bool tdi) {
 }
 
 #if USE_SPI1
-void jtag_transfer(uint8_t length, const uint8_t *in, uint8_t *out) {
+void jtag_transfer(uint16_t length, const uint8_t *in, uint8_t *out) {
   uint32_t byte_length = max_frequency ? length/8 : 0;
-  uint8_t remaining_length = max_frequency ? length & 7 : length;
+  uint16_t remaining_length = max_frequency ? length & 7 : length;
   uint32_t xfer_in_i = 0;
   uint32_t xfer_out_i = 0;
 
@@ -398,8 +409,7 @@ void jtag_transfer(uint8_t length, const uint8_t *in, uint8_t *out) {
 }
 
 #else
-void jtag_transfer(uint8_t length, const uint8_t *in, uint8_t *out) {
-
+void jtag_transfer(uint16_t length, const uint8_t *in, uint8_t *out) {
   jtag_transfer_internal(length, in, out);
 }
 

diff --git a/src/jtag.h b/src/jtag.h
@@ -87,7 +87,7 @@ void jtag_set_srst(uint8_t value);
  * @param in Input data
  * @param out Output data
  */
-void jtag_transfer(uint8_t length, const uint8_t *in,
+void jtag_transfer(uint16_t length, const uint8_t *in,
 		   uint8_t *out);
 
 /**
@@ -110,7 +110,7 @@ void jtag_strobe(uint8_t pulses, bool tms, bool tdi);
 #define HW_baite 2
 #define HW_stlinkv2white 3
 
-#if (PLATFORM == HW_bluepill) ||  (PLATFORM == HW_stlinkv2white)
+#if (PLATFORM == HW_bluepill)  || (PLATFORM == HW_stlinkv2white)
 #define USE_SPI1 1
 #else
 #define USE_SPI1 0