Hello list,

the attached patch fixes several issues in presto.c
- lower jtag speeds (higher divisor) was used, TDI was not changed on falling 
TCK edge as it should
- reset signal was release upon any TMS transition, making it impossible to use 
reset halt
- added khz() and speed_div() functions

and bitq.c
- TAP state changed to TLR when SRST goes active with srst_pulls_trst, as in 
all other drivers

Please commit
  Pavel
Index: src/jtag/bitq.c
===================================================================
--- src/jtag/bitq.c     (revision 714)
+++ src/jtag/bitq.c     (working copy)
@@ -283,6 +283,10 @@
 #ifdef _DEBUG_JTAG_IO_
                                LOG_DEBUG("reset trst: %i srst %i", 
cmd->cmd.reset->trst, cmd->cmd.reset->srst);
 #endif
+                               if ((cmd->cmd.reset->trst == 1) || 
(cmd->cmd.reset->srst && (jtag_reset_config & RESET_SRST_PULLS_TRST)))
+                               {
+                                       cur_state = TAP_TLR;
+                               }
                                bitq_interface->reset(cmd->cmd.reset->trst, 
cmd->cmd.reset->srst);
                                if (bitq_interface->in_rdy()) bitq_in_proc();
                                break;
Index: src/jtag/presto.c
===================================================================
--- src/jtag/presto.c   (revision 714)
+++ src/jtag/presto.c   (working copy)
@@ -51,6 +51,8 @@
 
 
 int presto_jtag_speed(int speed);
+int presto_jtag_khz(int khz, int *jtag_speed);
+int presto_jtag_speed_div(int speed, int *khz);
 int presto_jtag_register_commands(struct command_context_s *cmd_ctx);
 int presto_jtag_init(void);
 int presto_jtag_quit(void);
@@ -60,6 +62,8 @@
        .name = "presto",
        .execute_queue = bitq_execute_queue,
        .speed = presto_jtag_speed,
+       .khz = presto_jtag_khz,
+       .speed_div = presto_jtag_speed_div,
        .register_commands = presto_jtag_register_commands,
        .init = presto_jtag_init,
        .quit = presto_jtag_quit,
@@ -121,10 +125,13 @@
 
        int jtag_tms; /* last tms state */
        int jtag_tck; /* last tck state */
+       int jtag_rst; /* last trst state */
 
        int jtag_tdi_data;
        int jtag_tdi_count;
 
+       int jtag_speed;
+       
 } presto_t;
 
 presto_t presto_state;
@@ -422,9 +429,12 @@
 
        presto->jtag_tms=0;
        presto->jtag_tck=0;
+       presto->jtag_rst=0;
        presto->jtag_tdi_data=0;
        presto->jtag_tdi_count=0;
 
+       presto->jtag_speed=0;
+       
 #if BUILD_PRESTO_FTD2XX == 1
        return presto_open_ftd2xx(req_serial);
 #elif BUILD_PRESTO_LIBFTDI == 1
@@ -567,81 +577,95 @@
 /* -------------------------------------------------------------------------- 
*/
 
 
+int presto_tdi_flush(void)
+{
+       if (presto->jtag_tdi_count == 0)
+               return 0;
+
+       if (presto->jtag_tck == 0)
+       {
+               LOG_ERROR("BUG: unexpected TAP condition, TCK low");
+               return -1;
+       }
+
+       presto->jtag_tdi_data |= (presto->jtag_tdi_count - 1) << 4;
+       presto_sendbyte(presto->jtag_tdi_data);
+       presto->jtag_tdi_count = 0;
+       presto->jtag_tdi_data = 0;
+       
+       return 0;
+}
+
+
+int presto_tck_idle(void)
+{
+       if (presto->jtag_tck == 1)
+       {
+               presto_sendbyte(0xCA);
+               presto->jtag_tck = 0;
+       }
+       
+       return 0;
+}
+
+
+/* -------------------------------------------------------------------------- 
*/
+
+
 int presto_bitq_out(int tms, int tdi, int tdo_req)
 {
-       unsigned char cmdparam;
+       int i;
+       unsigned char cmd;
 
        if (presto->jtag_tck == 0)
        {
-               presto_sendbyte(0xA4); /* jtag activity */
-               presto->jtag_tck = 1; /* clock remains high after the function 
returns */
-               /* do just a single tick first, accelerated shifting needs 
TCK=1 */
+               presto_sendbyte(0xA4); /* LED idicator - JTAG active */
        }
-       else if (!tdo_req && tms == presto->jtag_tms)
+       else if (presto->jtag_speed == 0 && !tdo_req && tms == presto->jtag_tms)
        {
-               if (presto->jtag_tdi_count == 0)
-                       presto->jtag_tdi_data = (tdi != 0);
-               else
-                       presto->jtag_tdi_data |= (tdi != 0) << 
presto->jtag_tdi_count;
+               presto->jtag_tdi_data |= (tdi != 0) << presto->jtag_tdi_count;
 
                if (++presto->jtag_tdi_count == 4)
-               {
-                       presto->jtag_tdi_data |= (presto->jtag_tdi_count - 1) 
<< 4;
-                       presto_sendbyte(presto->jtag_tdi_data);
-                       presto->jtag_tdi_count = 0;
-               }
+                       presto_tdi_flush();
+
                return 0;
        }
 
-       if (presto->jtag_tdi_count)
-       {
-               presto->jtag_tdi_data |= (presto->jtag_tdi_count - 1) << 4;
-               presto_sendbyte(presto->jtag_tdi_data);
-               presto->jtag_tdi_count = 0;
-       }
+       presto_tdi_flush();
 
-       if (tdi)
-               cmdparam = 0x0B;
-       else
-               cmdparam = 0x0A;
+       cmd = tdi ? 0xCB : 0xCA;
+       presto_sendbyte(cmd);
 
-       presto_sendbyte( 0xC0 | cmdparam);
-
        if (tms != presto->jtag_tms)
        {
-               if (tms)
-                       presto_sendbyte(0xEC);
-               else
-                       presto_sendbyte(0xE8);
+               presto_sendbyte((tms ? 0xEC : 0xE8) | (presto->jtag_rst ? 0x02 
: 0));
                presto->jtag_tms = tms;
        }
 
-       if (tdo_req)
-               presto_sendbyte(0xD4|cmdparam);
-       else
-               presto_sendbyte(0xC4|cmdparam);
+       /* delay with TCK low */
+       for (i=presto->jtag_speed; i>1; i--)
+               presto_sendbyte(cmd);
 
+       cmd |= 0x04;
+       presto_sendbyte(cmd | (tdo_req ? 0x10 : 0));
+
+       /* delay with TCK high */
+       for (i=presto->jtag_speed; i>1; i--)
+               presto_sendbyte(cmd);
+
+       presto->jtag_tck = 1;
+
        return 0;
 }
 
 
 int presto_bitq_flush(void)
 {
-       if (presto->jtag_tdi_count)
-       {
-               presto->jtag_tdi_data |= (presto->jtag_tdi_count - 1) << 4;
-               presto_sendbyte(presto->jtag_tdi_data);
-               presto->jtag_tdi_count = 0;
-       }
+       presto_tdi_flush();
+       presto_tck_idle();
 
-       if (presto->jtag_tck == 1) 
-       {
-               presto_sendbyte(0xCA);
-               presto->jtag_tck = 0;
-       }
+       presto_sendbyte(0xA0); /* LED idicator - JTAG idle */
 
-       presto_sendbyte(0xA0);
-
        return presto_flush();
 }
 
@@ -667,11 +691,8 @@
 {
        long waits;
 
-       if (presto->jtag_tck == 1) 
-       {
-               presto_sendbyte(0xCA);
-               presto->jtag_tck = 0;
-       }
+       presto_tdi_flush();
+       presto_tck_idle();
 
        if (us > 100000)
        {
@@ -690,47 +711,70 @@
 
 int presto_bitq_reset(int trst, int srst)
 {
-       unsigned char cmd;
+       presto_tdi_flush();
+       presto_tck_idle();
 
-       if (presto->jtag_tck == 1) 
-       {
-               presto_sendbyte(0xCA);
-               presto->jtag_tck = 0;
-       }
+       /* add a delay after possible TCK transition */
+       presto_sendbyte(0x80);
+       presto_sendbyte(0x80);
 
-       cmd = 0xE8;
-       if (presto->jtag_tms)
-               cmd |= 0x04;
+       presto->jtag_rst = trst || srst;
+       presto_sendbyte((presto->jtag_rst ? 0xEA : 0xE8) | (presto->jtag_tms ? 
0x04 : 0));
 
-       if (trst || srst)
-               cmd |= 0x02;
-
-       presto_sendbyte(cmd);
        return 0;
 }
 
 
 /* -------------------------------------------------------------------------- 
*/
 
-char *presto_speed_text[4] =
+
+int presto_jtag_khz(int khz, int *jtag_speed)
 {
-       "3 MHz",
-       "1.5 MHz",
-       "750 kHz",
-       "93.75 kHz"
-};
+       if (khz < 0)
+       {
+               *jtag_speed=0;
+               return ERROR_INVALID_ARGUMENTS;
+       }
 
+       if (khz >= 3000) *jtag_speed = 0;
+       else *jtag_speed = (1000+khz-1)/khz;
+       
+       return 0;
+}
+
+
+int presto_jtag_speed_div(int speed, int *khz)
+{
+       if ((speed < 0) || (speed > 1000))
+       {
+               *khz=0;
+               return ERROR_INVALID_ARGUMENTS;
+       }
+
+       if (speed == 0) *khz = 3000;
+       else *khz = 1000/speed;
+       
+       return 0;
+}
+
+
 int presto_jtag_speed(int speed)
 {
-
-       if ((speed < 0) || (speed > 3))
+       int khz;
+       
+       if (presto_jtag_speed_div(speed, &khz))
        {
-               LOG_INFO("valid speed values: 0 (3 MHz), 1 (1.5 MHz), 2 (750 
kHz) and 3 (93.75 kHz)");
                return ERROR_INVALID_ARGUMENTS;
        }
 
-       LOG_INFO("setting speed to %d, max. TCK freq. is %s", speed, 
presto_speed_text[speed]);
-       return presto_sendbyte(0xA8 | speed);
+       presto->jtag_speed = speed;
+       
+       if (khz%1000 == 0)
+               LOG_INFO("setting speed to %d, max. TCK freq. is %d MHz", 
speed, khz/1000);
+       else
+               LOG_INFO("setting speed to %d, max. TCK freq. is %d kHz", 
speed, khz);
+       
+       return 0;
 }
 
 
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