main: invoke jtag_interface_quit() explicitly
[fw/openocd] / src / jtag / presto.c
index 084ae91799e91230d4392395579638b26c8a1739..f4e689c2a527f7eb229ab517c184c362e518b88e 100644 (file)
 
 #if IS_CYGWIN == 1
 #include "windows.h"
-#undef ERROR
 #endif
 
-#include "replacements.h"
-
-/* project specific includes */
-#include "log.h"
-#include "types.h"
-#include "jtag.h"
-#include "configuration.h"
+#include "interface.h"
 #include "time_support.h"
 #include "bitq.h"
 
-/* system includes */
-#include <string.h>
-#include <stdlib.h>
-#include <unistd.h>
-
-#include <sys/time.h>
-#include <time.h>
 
 /* PRESTO access library includes */
 #if BUILD_PRESTO_FTD2XX == 1
 #include <ftd2xx.h>
 #elif BUILD_PRESTO_LIBFTDI == 1
 #include <ftdi.h>
+#else
+#error "BUG: either FTD2XX and LIBFTDI has to be used"
 #endif
 
-
-int presto_jtag_speed(int speed);
-int presto_jtag_register_commands(struct command_context_s *cmd_ctx);
-int presto_jtag_init(void);
-int presto_jtag_quit(void);
-
-jtag_interface_t presto_interface =
-{
-       .name = "presto",
-       .execute_queue = bitq_execute_queue,
-       .support_pathmove = 1,
-       .speed = presto_jtag_speed,
-       .register_commands = presto_jtag_register_commands,
-       .init = presto_jtag_init,
-       .quit = presto_jtag_quit,
-};
-
-
-int presto_bitq_out(int tms, int tdi, int tdo_req);
-int presto_bitq_flush(void);
-int presto_bitq_sleep(unsigned long us);
-int presto_bitq_reset(int trst, int srst);
-int presto_bitq_in_rdy(void);
-int presto_bitq_in(void);
-
-bitq_interface_t presto_bitq =
-{
-       .out = presto_bitq_out,
-       .flush = presto_bitq_flush,
-       .sleep = presto_bitq_sleep,
-       .reset = presto_bitq_reset,
-       .in_rdy = presto_bitq_in_rdy,
-       .in = presto_bitq_in,
-};
-
-
 /* -------------------------------------------------------------------------- */
 
-
 #define FT_DEVICE_NAME_LEN 64
 #define FT_DEVICE_SERNUM_LEN 64
 
@@ -99,8 +50,7 @@ bitq_interface_t presto_bitq =
 
 #define BUFFER_SIZE (64*62)
 
-typedef struct presto_s
-{
+struct presto {
 #if BUILD_PRESTO_FTD2XX == 1
        FT_HANDLE handle;
        FT_STATUS status;
@@ -108,13 +58,13 @@ typedef struct presto_s
        struct ftdi_context ftdic;
        int retval;
 #endif
-       
+
        char serial[FT_DEVICE_SERNUM_LEN];
 
-       u8 buff_out[BUFFER_SIZE];
+       uint8_t buff_out[BUFFER_SIZE];
        int buff_out_pos;
 
-       u8 buff_in[BUFFER_SIZE];
+       uint8_t buff_in[BUFFER_SIZE];
        int buff_in_exp; /* expected in buffer length */
        int buff_in_len; /* length of data received */
        int buff_in_pos;
@@ -124,256 +74,316 @@ typedef struct presto_s
 
        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;
 
-} presto_t;
+       int jtag_speed;
+};
 
-presto_t presto_state;
-presto_t *presto = &presto_state;
+static struct presto presto_state;
+static struct presto *presto = &presto_state;
 
-u8 presto_init_seq[] =
+static uint8_t presto_init_seq[] =
 {
        0x80, 0xA0, 0xA8, 0xB0, 0xC0, 0xE0
 };
 
-int presto_write(u8 *buf, int size, u32* bytes_written)
+static int presto_write(uint8_t *buf, uint32_t size)
 {
 #if BUILD_PRESTO_FTD2XX == 1
-       DWORD dw_bytes_written;
-       if ((presto->status = FT_Write(presto->handle, buf, size, &dw_bytes_written)) != FT_OK)
+       DWORD ftbytes;
+       if ((presto->status = FT_Write(presto->handle, buf, size, &ftbytes)) != FT_OK)
        {
-               *bytes_written = dw_bytes_written;
-               ERROR("FT_Write returned: %lu", presto->status);
+               LOG_ERROR("FT_Write returned: %lu", presto->status);
                return ERROR_JTAG_DEVICE_ERROR;
        }
-       else
-       {
-               *bytes_written = dw_bytes_written;
-               return ERROR_OK;        
-       }
+
 #elif BUILD_PRESTO_LIBFTDI == 1
+       uint32_t ftbytes;
        if ((presto->retval = ftdi_write_data(&presto->ftdic, buf, size)) < 0)
        {
-               *bytes_written = 0;
-               ERROR("ftdi_write_data: %s", ftdi_get_error_string(&presto->ftdic));
+               LOG_ERROR("ftdi_write_data: %s", ftdi_get_error_string(&presto->ftdic));
                return ERROR_JTAG_DEVICE_ERROR;
        }
-       else
+       ftbytes = presto->retval;
+#endif
+
+       if (ftbytes != size)
        {
-               *bytes_written = retval;
-               return ERROR_OK;        
+               LOG_ERROR("couldn't write the requested number of bytes to PRESTO (%u < %u)",
+                         (unsigned)ftbytes, (unsigned)size);
+               return ERROR_JTAG_DEVICE_ERROR;
        }
-#endif
+
+       return ERROR_OK;
 }
 
-int presto_read(u8* buf, int size, u32* bytes_read)
+static int presto_read(uint8_t* buf, uint32_t size)
 {
 #if BUILD_PRESTO_FTD2XX == 1
-       DWORD dw_bytes_read;
-       int timeout = 5;
-       *bytes_read = 0;
-
-       while ((*bytes_read < size) && timeout--)
+       DWORD ftbytes;
+       if ((presto->status = FT_Read(presto->handle, buf, size, &ftbytes)) != FT_OK)
        {
-               if ((presto->status = FT_Read(presto->handle, buf + *bytes_read, size - 
-                       *bytes_read, &dw_bytes_read)) != FT_OK)         
-               {
-                       *bytes_read = 0; 
-                       ERROR("FT_Read returned: %lu", presto->status);
-                       return ERROR_JTAG_DEVICE_ERROR;
-               }
-               *bytes_read += dw_bytes_read; 
+               LOG_ERROR("FT_Read returned: %lu", presto->status);
+               return ERROR_JTAG_DEVICE_ERROR;
        }
+
 #elif BUILD_PRESTO_LIBFTDI == 1
-       int timeout = 100;
-       *bytes_read = 0;
-       
-       while ((*bytes_read < size) && timeout--)
+       uint32_t ftbytes = 0;
+
+       struct timeval timeout, now;
+       gettimeofday(&timeout, NULL);
+       timeval_add_time(&timeout, 1, 0); /* one second timeout */
+
+       while (ftbytes < size)
        {
-               if ((presto->retval = ftdi_read_data(&presto->ftdic, buf + *bytes_read, size - *bytes_read)) < 0)
+               if ((presto->retval = ftdi_read_data(&presto->ftdic, buf + ftbytes, size - ftbytes)) < 0)
                {
-                       *bytes_read = 0;
-                       ERROR("ftdi_read_data: %s", ftdi_get_error_string(&presto->ftdic));
+                       LOG_ERROR("ftdi_read_data: %s", ftdi_get_error_string(&presto->ftdic));
                        return ERROR_JTAG_DEVICE_ERROR;
                }
-               *bytes_read += retval;
+               ftbytes += presto->retval;
+
+               gettimeofday(&now, NULL);
+               if ((now.tv_sec > timeout.tv_sec) || ((now.tv_sec == timeout.tv_sec) && (now.tv_usec > timeout.tv_usec)))
+                       break;
        }
 #endif
 
-       if (*bytes_read < size)
+       if (ftbytes != size)
        {
-               ERROR("couldn't read the requested number of bytes from PRESTO (%i < %i)", *bytes_read, size);
+               /* this is just a warning, there might have been timeout when detecting PRESTO, which is not fatal */
+               LOG_WARNING("couldn't read the requested number of bytes from PRESTO (%u < %u)",
+                           (unsigned)ftbytes, (unsigned)size);
                return ERROR_JTAG_DEVICE_ERROR;
        }
-       
+
        return ERROR_OK;
 }
 
 #if BUILD_PRESTO_FTD2XX == 1
-int presto_open_ftd2xx(char *req_serial)
+static int presto_open_ftd2xx(char *req_serial)
 {
-       int i;
+       uint32_t i;
        DWORD numdevs;
        DWORD vidpid;
        char devname[FT_DEVICE_NAME_LEN];
        FT_DEVICE device;
 
        BYTE presto_data;
-       unsigned long ftbytes;
+       DWORD ftbytes;
 
        presto->handle = (FT_HANDLE)INVALID_HANDLE_VALUE;
-       
+
 #if IS_WIN32 == 0
        /* Add non-standard Vid/Pid to the linux driver */
        if ((presto->status = FT_SetVIDPID(PRESTO_VID, PRESTO_PID)) != FT_OK)
        {
-               ERROR("couldn't add PRESTO VID/PID");
+               LOG_ERROR("couldn't add PRESTO VID/PID");
                exit(-1);
        }
 #endif
 
        if ((presto->status = FT_ListDevices(&numdevs, NULL, FT_LIST_NUMBER_ONLY)) != FT_OK)
        {
-               ERROR("FT_ListDevices failed: %i", (int)presto->status);
-               return ERROR_JTAG_INIT_FAILED;
+               LOG_ERROR("FT_ListDevices failed: %i", (int)presto->status);
+               return ERROR_JTAG_DEVICE_ERROR;
        }
-       
+
+       LOG_DEBUG("FTDI devices available: %lu", numdevs);
        for (i = 0; i < numdevs; i++)
        {
-               if (FT_Open(i, &(presto->handle)) != FT_OK)
+               if ((presto->status = FT_Open(i, &(presto->handle))) != FT_OK)
                {
-                       ERROR("FT_Open failed: %i", (int)presto->status);
+                       /* this is not fatal, the device may be legitimately open by other process, hence debug message only */
+                       LOG_DEBUG("FT_Open failed: %i", (int)presto->status);
                        continue;
                }
-                       
-               if (FT_GetDeviceInfo(presto->handle, &device, &vidpid,
-                               presto->serial, devname, NULL) == FT_OK)
+               LOG_DEBUG("FTDI device %i open", (int)i);
+
+               if ((presto->status = FT_GetDeviceInfo(presto->handle, &device, &vidpid,
+                               presto->serial, devname, NULL)) == FT_OK)
                {
                        if (vidpid == PRESTO_VID_PID
                                        && (req_serial == NULL || !strcmp(presto->serial, req_serial)))
                                break;
                }
-               
+               else
+                       LOG_DEBUG("FT_GetDeviceInfo failed: %lu", presto->status);
+
+               LOG_DEBUG("FTDI device %i does not match, closing", (int)i);
                FT_Close(presto->handle);
                presto->handle = (FT_HANDLE)INVALID_HANDLE_VALUE;
        }
 
        if (presto->handle == (FT_HANDLE)INVALID_HANDLE_VALUE)
-               return ERROR_JTAG_INIT_FAILED;
+               return ERROR_JTAG_DEVICE_ERROR; /* presto not open, return */
+
        if ((presto->status = FT_SetLatencyTimer(presto->handle, 1)) != FT_OK)
-               return ERROR_JTAG_INIT_FAILED;
+               return ERROR_JTAG_DEVICE_ERROR;
+
+
        if ((presto->status = FT_SetTimeouts(presto->handle, 100, 0)) != FT_OK)
-               return ERROR_JTAG_INIT_FAILED;
+               return ERROR_JTAG_DEVICE_ERROR;
+
        if ((presto->status = FT_Purge(presto->handle, FT_PURGE_TX | FT_PURGE_RX)) != FT_OK)
-               return ERROR_JTAG_INIT_FAILED;
+               return ERROR_JTAG_DEVICE_ERROR;
 
        presto_data = 0xD0;
        if ((presto->status = FT_Write(presto->handle, &presto_data, 1, &ftbytes)) != FT_OK)
-               return ERROR_JTAG_INIT_FAILED;
+               return ERROR_JTAG_DEVICE_ERROR;
+
+       /* delay between first write/read turnaround (after purge?) necessary under Linux for unknown reason,
+          probably a bug in library threading */
+       usleep(100000);
        if ((presto->status = FT_Read(presto->handle, &presto_data, 1, &ftbytes)) != FT_OK)
-               return ERROR_JTAG_INIT_FAILED;
+               return ERROR_JTAG_DEVICE_ERROR;
 
-       if (ftbytes!=1)
+       if (ftbytes != 1)
        {
-               if ((presto->status = FT_SetBitMode(presto->handle, 0x80, 1)) != FT_OK)
-                       return ERROR_JTAG_INIT_FAILED;
+               LOG_DEBUG("PRESTO reset");
+
                if ((presto->status = FT_Purge(presto->handle, FT_PURGE_TX | FT_PURGE_RX)) != FT_OK)
-                       return ERROR_JTAG_INIT_FAILED ;
+                       return ERROR_JTAG_DEVICE_ERROR;
+               if ((presto->status = FT_SetBitMode(presto->handle, 0x80, 1)) != FT_OK)
+                       return ERROR_JTAG_DEVICE_ERROR;
                if ((presto->status = FT_SetBaudRate(presto->handle, 9600)) != FT_OK)
-                       return ERROR_JTAG_INIT_FAILED;
+                       return ERROR_JTAG_DEVICE_ERROR;
 
                presto_data = 0;
                for (i = 0; i < 4 * 62; i++)
-                       if ((presto->status=FT_Write(presto->handle, &presto_data, 1, &ftbytes)) != FT_OK)
-                               return ERROR_JTAG_INIT_FAILED;
+                       if ((presto->status = FT_Write(presto->handle, &presto_data, 1, &ftbytes)) != FT_OK)
+                               return ERROR_JTAG_DEVICE_ERROR;
 
                usleep(100000);
 
                if ((presto->status = FT_SetBitMode(presto->handle, 0x00, 0)) != FT_OK)
-                       return ERROR_JTAG_INIT_FAILED;
+                       return ERROR_JTAG_DEVICE_ERROR;
+
                if ((presto->status = FT_Purge(presto->handle, FT_PURGE_TX | FT_PURGE_RX)) != FT_OK)
-                       return ERROR_JTAG_INIT_FAILED;
+                       return ERROR_JTAG_DEVICE_ERROR;
 
                presto_data = 0xD0;
                if ((presto->status = FT_Write(presto->handle, &presto_data, 1, &ftbytes)) != FT_OK)
-                       return ERROR_JTAG_INIT_FAILED;
+                       return ERROR_JTAG_DEVICE_ERROR;
+
+               /* delay between first write/read turnaround (after purge?) necessary under Linux for unknown reason,
+                  probably a bug in library threading */
+               usleep(100000);
                if ((presto->status = FT_Read(presto->handle, &presto_data, 1, &ftbytes)) != FT_OK)
-                       return ERROR_JTAG_INIT_FAILED;
-               if (ftbytes!=1)
-                       return ERROR_JTAG_INIT_FAILED;
+                       return ERROR_JTAG_DEVICE_ERROR;
+
+               if (ftbytes != 1)
+               {
+                       LOG_DEBUG("PRESTO not responding");
+                       return ERROR_JTAG_DEVICE_ERROR;
+               }
        }
 
        if ((presto->status = FT_SetTimeouts(presto->handle, 0, 0)) != FT_OK)
-               return ERROR_JTAG_INIT_FAILED;
+               return ERROR_JTAG_DEVICE_ERROR;
+
 
        presto->status = FT_Write(presto->handle, &presto_init_seq, sizeof(presto_init_seq), &ftbytes);
-       if (presto->status != FT_OK)
-               return ERROR_JTAG_INIT_FAILED;
-       if (ftbytes != sizeof(presto_init_seq))
-               return ERROR_JTAG_INIT_FAILED;
+       if (presto->status != FT_OK || ftbytes != sizeof(presto_init_seq))
+               return ERROR_JTAG_DEVICE_ERROR;
 
        return ERROR_OK;
 }
 
 #elif BUILD_PRESTO_LIBFTDI == 1
-int presto_open_libftdi(char *req_serial)
+static int presto_open_libftdi(char *req_serial)
 {
-       u8 presto_data;
-       u32 ftbytes;
-               
-       DEBUG("searching for presto JTAG interface using libftdi");
+       uint8_t presto_data;
+
+       LOG_DEBUG("searching for PRESTO using libftdi");
+
+       /* initialize FTDI context structure */
+       if (ftdi_init(&presto->ftdic) < 0)
+       {
+               LOG_ERROR("unable to init libftdi: %s", presto->ftdic.error_str);
+               return ERROR_JTAG_DEVICE_ERROR;
+       }
 
        /* context, vendor id, product id */
        if (ftdi_usb_open_desc(&presto->ftdic, PRESTO_VID, PRESTO_PID, NULL, req_serial) < 0)
        {
-               ERROR("unable to open presto: %s", presto->ftdic.error_str);
-               return ERROR_JTAG_INIT_FAILED;
+               LOG_ERROR("unable to open PRESTO: %s", presto->ftdic.error_str);
+               return ERROR_JTAG_DEVICE_ERROR;
        }
-       
+
        if (ftdi_usb_reset(&presto->ftdic) < 0)
        {
-               ERROR("unable to reset presto device");
-               return ERROR_JTAG_INIT_FAILED;
+               LOG_ERROR("unable to reset PRESTO device");
+               return ERROR_JTAG_DEVICE_ERROR;
        }
 
        if (ftdi_set_latency_timer(&presto->ftdic, 1) < 0)
        {
-               ERROR("unable to set latency timer");
-               return ERROR_JTAG_INIT_FAILED;
+               LOG_ERROR("unable to set latency timer");
+               return ERROR_JTAG_DEVICE_ERROR;
        }
 
        if (ftdi_usb_purge_buffers(&presto->ftdic) < 0)
        {
-               ERROR("unable to purge presto buffer");
-               return ERROR_JTAG_INIT_FAILED;
+               LOG_ERROR("unable to purge PRESTO buffers");
+               return ERROR_JTAG_DEVICE_ERROR;
        }
-       
+
        presto_data = 0xD0;
-       if ((presto->retval = presto_write(&presto_data, 1, &ftbytes)) != ERROR_OK)
-               return ERROR_JTAG_INIT_FAILED;
-       if ((presto->retval = presto_read(&presto_data, 1, &ftbytes)) != ERROR_OK)
-               return ERROR_JTAG_INIT_FAILED;
-       
+       if (presto_write(&presto_data, 1) != ERROR_OK)
+       {
+               LOG_ERROR("error writing to PRESTO");
+               return ERROR_JTAG_DEVICE_ERROR;
+       }
+
+       if (presto_read(&presto_data, 1) != ERROR_OK)
+       {
+               LOG_DEBUG("no response from PRESTO, retrying");
+
+               if (ftdi_usb_purge_buffers(&presto->ftdic) < 0)
+                       return ERROR_JTAG_DEVICE_ERROR;
+
+               presto_data = 0xD0;
+               if (presto_write(&presto_data, 1) != ERROR_OK)
+                       return ERROR_JTAG_DEVICE_ERROR;
+
+               if (presto_read(&presto_data, 1) != ERROR_OK)
+               {
+                       LOG_ERROR("no response from PRESTO, giving up");
+                       return ERROR_JTAG_DEVICE_ERROR;
+               }
+       }
+
+       if (presto_write(presto_init_seq, sizeof(presto_init_seq)) != ERROR_OK)
+       {
+               LOG_ERROR("error writing PRESTO init sequence");
+               return ERROR_JTAG_DEVICE_ERROR;
+       }
+
        return ERROR_OK;
 }
 #endif /* BUILD_PRESTO_LIBFTDI == 1 */
 
-int presto_open(char *req_serial)
+static int presto_open(char *req_serial)
 {
-       presto->buff_out_pos=0;
-       presto->buff_in_pos=0;
-       presto->buff_in_len=0;
-       presto->buff_in_exp=0;
+       presto->buff_out_pos = 0;
+       presto->buff_in_pos = 0;
+       presto->buff_in_len = 0;
+       presto->buff_in_exp = 0;
 
-       presto->total_out=0;
-       presto->total_in=0;
+       presto->total_out = 0;
+       presto->total_in = 0;
 
-       presto->jtag_tms=0;
-       presto->jtag_tck=0;
-       presto->jtag_tdi_data=0;
-       presto->jtag_tdi_count=0;
+       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);
@@ -382,80 +392,72 @@ int presto_open(char *req_serial)
 #endif
 }
 
-int presto_close(void)
+static int presto_close(void)
 {
 
        int result = ERROR_OK;
 
-#if BUID_PRESTO_FTD2XX == 1
+#if BUILD_PRESTO_FTD2XX == 1
        unsigned long ftbytes;
 
        if (presto->handle == (FT_HANDLE)INVALID_HANDLE_VALUE)
                return result;
 
-       presto->status = FT_Write(presto->handle, &presto_init_seq, sizeof(presto_init_seq), &ftbytes);
+       presto->status = FT_Purge(presto->handle, FT_PURGE_TX | FT_PURGE_RX);
        if (presto->status != FT_OK)
-               result = PRST_ERR;
-       if (ftbytes != sizeof(presto_init_seq))
-               result = PRST_TIMEOUT;
+               result = ERROR_JTAG_DEVICE_ERROR;
+
+       presto->status = FT_Write(presto->handle, &presto_init_seq, sizeof(presto_init_seq), &ftbytes);
+       if (presto->status != FT_OK || ftbytes != sizeof(presto_init_seq))
+               result = ERROR_JTAG_DEVICE_ERROR;
 
        if ((presto->status = FT_SetLatencyTimer(presto->handle, 16)) != FT_OK)
-               result = PRST_ERR;
+               result = ERROR_JTAG_DEVICE_ERROR;
 
        if ((presto->status = FT_Close(presto->handle)) != FT_OK)
-               result = PRST_ERR;
+               result = ERROR_JTAG_DEVICE_ERROR;
        else
                presto->handle = (FT_HANDLE)INVALID_HANDLE_VALUE;
-       
+
 #elif BUILD_PRESTO_LIBFTDI == 1
-       
-       if ((presto->retval = ftdi_write_data(&presto->ftdic, presto_init_seq, sizeof(presto_init_seq))) < 0)
-       {
+
+       if ((presto->retval = ftdi_write_data(&presto->ftdic, presto_init_seq, sizeof(presto_init_seq))) != sizeof(presto_init_seq))
                result = ERROR_JTAG_DEVICE_ERROR;
-       }
-       
+
        if ((presto->retval = ftdi_set_latency_timer(&presto->ftdic, 16)) < 0)
-       {
                result = ERROR_JTAG_DEVICE_ERROR;
-       }
-       
-       ftdi_deinit(&presto->ftdic);
-       
+
+       if ((presto->retval = ftdi_usb_close(&presto->ftdic)) < 0)
+               result = ERROR_JTAG_DEVICE_ERROR;
+       else
+               ftdi_deinit(&presto->ftdic);
 #endif
 
        return result;
 }
 
-
-int presto_flush(void)
+static int presto_flush(void)
 {
-       u32 ftbytes;
-
        if (presto->buff_out_pos == 0)
                return ERROR_OK;
 
 #if BUILD_PRESTO_FTD2XX == 1
        if (presto->status != FT_OK)
 #elif BUILD_PRESTO_LIBFTDI == 1
-       if (presto->retval != ERROR_OK)
+       if (presto->retval < 0)
 #endif
-               return ERROR_JTAG_DEVICE_ERROR;
-
-
-       if (presto_write(presto->buff_out, presto->buff_out_pos, &ftbytes) != ERROR_OK)
        {
-               presto->buff_out_pos = 0;
+               LOG_DEBUG("error in previous communication, canceling I/O operation");
                return ERROR_JTAG_DEVICE_ERROR;
        }
 
-       presto->total_out += ftbytes;
-
-       if (presto->buff_out_pos != ftbytes)
+       if (presto_write(presto->buff_out, presto->buff_out_pos) != ERROR_OK)
        {
                presto->buff_out_pos = 0;
                return ERROR_JTAG_DEVICE_ERROR;
        }
 
+       presto->total_out += presto->buff_out_pos;
        presto->buff_out_pos = 0;
 
        if (presto->buff_in_exp == 0)
@@ -464,165 +466,174 @@ int presto_flush(void)
        presto->buff_in_pos = 0;
        presto->buff_in_len = 0;
 
-       if (presto_read(presto->buff_in, presto->buff_in_exp, &ftbytes) != ERROR_OK)
-       {
-               presto->buff_in_exp = 0;
-               return ERROR_JTAG_DEVICE_ERROR;
-       }
-
-       presto->total_in += ftbytes;
-
-       if (ftbytes != presto->buff_in_exp)
+       if (presto_read(presto->buff_in, presto->buff_in_exp) != ERROR_OK)
        {
                presto->buff_in_exp = 0;
                return ERROR_JTAG_DEVICE_ERROR;
        }
 
+       presto->total_in += presto->buff_in_exp;
        presto->buff_in_len = presto->buff_in_exp;
        presto->buff_in_exp = 0;
 
        return ERROR_OK;
 }
 
-
-int presto_sendbyte(int data)
+static int presto_sendbyte(int data)
 {
        if (data == EOF) return presto_flush();
 
        if (presto->buff_out_pos < BUFFER_SIZE)
        {
-               presto->buff_out[presto->buff_out_pos++] = (u8)data;
+               presto->buff_out[presto->buff_out_pos++] = (uint8_t)data;
                if (((data & 0xC0) == 0x40) || ((data & 0xD0)== 0xD0))
                        presto->buff_in_exp++;
        }
        else
                return ERROR_JTAG_DEVICE_ERROR;
 
+#if BUILD_PRESTO_FTD2XX == 1
        if (presto->buff_out_pos >= BUFFER_SIZE)
+#elif BUILD_PRESTO_LIBFTDI == 1
+       /* libftdi does not do background read, be sure that USB IN buffer does not overflow (128 bytes only!) */
+       if (presto->buff_out_pos >= BUFFER_SIZE || presto->buff_in_exp == 128)
+#endif
                return presto_flush();
-       
+
        return ERROR_OK;
 }
 
-
-int presto_getbyte(void)
+#if 0
+static int presto_getbyte(void)
 {
        if (presto->buff_in_pos < presto->buff_in_len)
                return presto->buff_in[presto->buff_in_pos++];
 
        if (presto->buff_in_exp == 0)
                return -1;
-       
+
        if (presto_flush() != ERROR_OK)
                return -1;
 
-       if (presto->buff_in_pos<presto->buff_in_len)
+       if (presto->buff_in_pos < presto->buff_in_len)
                return presto->buff_in[presto->buff_in_pos++];
 
        return -1;
 }
-
+#endif
 
 /* -------------------------------------------------------------------------- */
 
-
-int presto_bitq_out(int tms, int tdi, int tdo_req)
+static int presto_tdi_flush(void)
 {
-       unsigned char cmdparam;
+       if (presto->jtag_tdi_count == 0)
+               return 0;
 
        if (presto->jtag_tck == 0)
        {
-               presto_sendbyte(0xA4);
-               presto->jtag_tck = 1;
+               LOG_ERROR("BUG: unexpected TAP condition, TCK low");
+               return -1;
        }
 
-       else if (!tdo_req && tms == presto->jtag_tms)
+       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;
+}
+
+static int presto_tck_idle(void)
+{
+       if (presto->jtag_tck == 1)
        {
-               if (presto->jtag_tdi_count == 0)
-                       presto->jtag_tdi_data = (tdi != 0);
-               else
-                       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;
-               }
-               return 0;
+               presto_sendbyte(0xCA);
+               presto->jtag_tck = 0;
        }
 
-       if (presto->jtag_tdi_count)
+       return 0;
+}
+
+/* -------------------------------------------------------------------------- */
+
+static int presto_bitq_out(int tms, int tdi, int tdo_req)
+{
+       int i;
+       unsigned char cmd;
+
+       if (presto->jtag_tck == 0)
        {
-               presto->jtag_tdi_data |= (presto->jtag_tdi_count - 1) << 4;
-               presto_sendbyte(presto->jtag_tdi_data);
-               presto->jtag_tdi_count = 0;
+               presto_sendbyte(0xA4); /* LED idicator - JTAG active */
        }
+       else if (presto->jtag_speed == 0 && !tdo_req && tms == presto->jtag_tms)
+       {
+               presto->jtag_tdi_data |= (tdi != 0) << presto->jtag_tdi_count;
 
-       if (tdi)
-               cmdparam = 0x0B;
-       else
-               cmdparam = 0x0A;
+               if (++presto->jtag_tdi_count == 4)
+                       presto_tdi_flush();
+
+               return 0;
+       }
 
-       presto_sendbyte( 0xC0 | cmdparam);
+       presto_tdi_flush();
+
+       cmd = tdi ? 0xCB : 0xCA;
+       presto_sendbyte(cmd);
 
        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)
+static 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_sendbyte(0xCA);
-       presto->jtag_tck = 0;
+       presto_tdi_flush();
+       presto_tck_idle();
 
-       presto_sendbyte(0xA0);
+       presto_sendbyte(0xA0); /* LED idicator - JTAG idle */
 
        return presto_flush();
 }
 
-
-int presto_bitq_in_rdy(void)
+static int presto_bitq_in_rdy(void)
 {
-       if (presto->buff_in_pos>=presto->buff_in_len)
+       if (presto->buff_in_pos >= presto->buff_in_len)
                return 0;
        return presto->buff_in_len-presto->buff_in_pos;
 }
 
-
-int presto_bitq_in(void)
+static int presto_bitq_in(void)
 {
-       if (presto->buff_in_pos>=presto->buff_in_len)
+       if (presto->buff_in_pos >= presto->buff_in_len)
                return -1;
        if (presto->buff_in[presto->buff_in_pos++]&0x08) return 1;
        return 0;
 }
 
-
-int presto_bitq_sleep(unsigned long us)
+static int presto_bitq_sleep(unsigned long us)
 {
        long waits;
 
+       presto_tdi_flush();
+       presto_tck_idle();
+
        if (us > 100000)
        {
                presto_bitq_flush();
@@ -637,83 +648,133 @@ int presto_bitq_sleep(unsigned long us)
        return 0;
 }
 
-
-int presto_bitq_reset(int trst, int srst)
+static int presto_bitq_reset(int trst, int srst)
 {
-       unsigned char cmd;
+       presto_tdi_flush();
+       presto_tck_idle();
 
-       cmd = 0xE8;
-       if (presto->jtag_tms)
-               cmd |= 0x04;
+       /* add a delay after possible TCK transition */
+       presto_sendbyte(0x80);
+       presto_sendbyte(0x80);
 
-       if (trst || srst)
-               cmd |= 0x02;
+       presto->jtag_rst = trst || srst;
+       presto_sendbyte((presto->jtag_rst ? 0xEA : 0xE8) | (presto->jtag_tms ? 0x04 : 0));
 
-       presto_sendbyte(cmd);
        return 0;
 }
 
+static struct bitq_interface presto_bitq = {
+               .out = &presto_bitq_out,
+               .flush = &presto_bitq_flush,
+               .sleep = &presto_bitq_sleep,
+               .reset = &presto_bitq_reset,
+               .in_rdy = &presto_bitq_in_rdy,
+               .in = &presto_bitq_in,
+       };
 
 /* -------------------------------------------------------------------------- */
 
+static int presto_jtag_khz(int khz, int *jtag_speed)
+{
+       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(int speed)
+static int presto_jtag_speed_div(int speed, int *khz)
 {
-       jtag_speed = speed;
-       return ERROR_OK;
+       if ((speed < 0) || (speed > 1000))
+       {
+               *khz = 0;
+               return ERROR_INVALID_ARGUMENTS;
+       }
+
+       if (speed == 0) *khz = 3000;
+       else *khz = 1000/speed;
+
+       return 0;
 }
 
+static int presto_jtag_speed(int speed)
+{
+       int khz;
+
+       if (presto_jtag_speed_div(speed, &khz))
+       {
+               return ERROR_INVALID_ARGUMENTS;
+       }
+
+       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;
+}
 
-char *presto_serial;
+static char *presto_serial;
 
-int presto_handle_serial_command(struct command_context_s *cmd_ctx, char *cmd, char **args, int argc)
+COMMAND_HANDLER(presto_handle_serial_command)
 {
-       if (argc == 1)
+       if (CMD_ARGC == 1)
        {
                if (presto_serial)
                        free(presto_serial);
-               presto_serial = strdup(args[0]);
+               presto_serial = strdup(CMD_ARGV[0]);
        }
        else
        {
-               ERROR("expected exactly one argument to presto_serial <serial-number>");
+               LOG_ERROR("expected exactly one argument to presto_serial <serial-number>");
        }
 
        return ERROR_OK;
 }
 
+static const struct command_registration presto_command_handlers[] = {
+       {
+               .name = "presto_serial",
+               .handler = &presto_handle_serial_command,
+               .mode = COMMAND_CONFIG,
+               .help = "configure serial port",
+               .usage = "<devname>",
+       },
+       COMMAND_REGISTRATION_DONE
+};
 
-int presto_jtag_register_commands(struct command_context_s *cmd_ctx)
-{
-       register_command(cmd_ctx, NULL, "presto_serial", presto_handle_serial_command,
-               COMMAND_CONFIG, NULL);
-       return ERROR_OK;
-}
-
-
-int presto_jtag_init(void)
+static int presto_jtag_init(void)
 {
        if (presto_open(presto_serial) != ERROR_OK)
        {
                presto_close();
                if (presto_serial != NULL)
-                       ERROR("Cannot open PRESTO, serial number '%s'", presto_serial);
+                       LOG_ERROR("Cannot open PRESTO, serial number '%s'", presto_serial);
                else
-                       ERROR("Cannot open PRESTO");
+                       LOG_ERROR("Cannot open PRESTO");
                return ERROR_JTAG_INIT_FAILED;
        }
-       INFO("PRESTO open, serial number '%s'", presto->serial);
-       
+       LOG_INFO("PRESTO open, serial number '%s'", presto->serial);
+
+       /* use JTAG speed setting from configuration file */
+       presto_jtag_speed(jtag_get_speed());
+
        bitq_interface = &presto_bitq;
        return ERROR_OK;
 }
 
-
-int presto_jtag_quit(void)
+static int presto_jtag_quit(void)
 {
        bitq_cleanup();
        presto_close();
-       INFO("PRESTO closed");
+       LOG_INFO("PRESTO closed");
 
        if (presto_serial)
        {
@@ -723,3 +784,17 @@ int presto_jtag_quit(void)
 
        return ERROR_OK;
 }
+
+struct jtag_interface presto_interface = {
+               .name = "presto",
+
+               .commands = presto_command_handlers,
+
+               .execute_queue = &bitq_execute_queue,
+               .speed = &presto_jtag_speed,
+               .khz = &presto_jtag_khz,
+               .speed_div = &presto_jtag_speed_div,
+
+               .init = &presto_jtag_init,
+               .quit = &presto_jtag_quit,
+       };