]> git.sur5r.net Git - openocd/blobdiff - src/jtag/presto.c
- added patch to change pathmove handling
[openocd] / src / jtag / presto.c
index fe54b1312fd95c7ac317a221f222946b9459e2ca..1e21c22bde8073d0e704a8431dbbee4f4a3315b3 100644 (file)
 #include <sys/time.h>
 #include <time.h>
 
-#include "ftd2xx.h"
+/* PRESTO access library includes */
+#if BUILD_PRESTO_FTD2XX == 1
+#include <ftd2xx.h>
+#elif BUILD_PRESTO_LIBFTDI == 1
+#include <ftdi.h>
+#endif
 
 
 int presto_jtag_speed(int speed);
@@ -56,7 +61,6 @@ 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,
@@ -67,7 +71,7 @@ jtag_interface_t presto_interface =
 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 rst, int en);
+int presto_bitq_reset(int trst, int srst);
 int presto_bitq_in_rdy(void);
 int presto_bitq_in(void);
 
@@ -89,25 +93,27 @@ bitq_interface_t presto_bitq =
 #define FT_DEVICE_SERNUM_LEN 64
 
 #define PRESTO_VID_PID 0x0403f1a0
-
-#define PRST_OK 0
-#define PRST_ERR 1
-#define PRST_TIMEOUT 2
+#define PRESTO_VID (0x0403)
+#define PRESTO_PID (0xf1a0)
 
 #define BUFFER_SIZE (64*62)
 
-
 typedef struct presto_s
 {
+#if BUILD_PRESTO_FTD2XX == 1
        FT_HANDLE handle;
        FT_STATUS status;
+#elif BUILD_PRESTO_LIBFTDI == 1
+       struct ftdi_context ftdic;
+       int retval;
+#endif
        
        char serial[FT_DEVICE_SERNUM_LEN];
 
-       BYTE buff_out[BUFFER_SIZE];
+       u8 buff_out[BUFFER_SIZE];
        int buff_out_pos;
 
-       BYTE buff_in[BUFFER_SIZE];
+       u8 buff_in[BUFFER_SIZE];
        int buff_in_exp; /* expected in buffer length */
        int buff_in_len; /* length of data received */
        int buff_in_pos;
@@ -124,18 +130,90 @@ typedef struct presto_s
 } presto_t;
 
 presto_t presto_state;
-presto_t *presto=&presto_state;
+presto_t *presto = &presto_state;
 
-BYTE presto_init_seq[] =
+u8 presto_init_seq[] =
 {
-       0x80,   0xA0,   0xA8,   0xB0,   0xC0,   0xE0
+       0x80, 0xA0, 0xA8, 0xB0, 0xC0, 0xE0
 };
 
+int presto_write(u8 *buf, int size, u32* bytes_written)
+{
+#if BUILD_PRESTO_FTD2XX == 1
+       DWORD dw_bytes_written;
+       if ((presto->status = FT_Write(presto->handle, buf, size, &dw_bytes_written)) != FT_OK)
+       {
+               *bytes_written = dw_bytes_written;
+               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
+       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));
+               return ERROR_JTAG_DEVICE_ERROR;
+       }
+       else
+       {
+               *bytes_written = retval;
+               return ERROR_OK;        
+       }
+#endif
+}
 
-int presto_open(char *req_serial)
+int presto_read(u8* buf, int size, u32* bytes_read)
+{
+#if BUILD_PRESTO_FTD2XX == 1
+       DWORD dw_bytes_read;
+       int timeout = 5;
+       *bytes_read = 0;
+
+       while ((*bytes_read < size) && timeout--)
+       {
+               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; 
+       }
+#elif BUILD_PRESTO_LIBFTDI == 1
+       int timeout = 100;
+       *bytes_read = 0;
+       
+       while ((*bytes_read < size) && timeout--)
+       {
+               if ((presto->retval = ftdi_read_data(&presto->ftdic, buf + *bytes_read, size - *bytes_read)) < 0)
+               {
+                       *bytes_read = 0;
+                       ERROR("ftdi_read_data: %s", ftdi_get_error_string(&presto->ftdic));
+                       return ERROR_JTAG_DEVICE_ERROR;
+               }
+               *bytes_read += retval;
+       }
+#endif
+
+       if (*bytes_read < size)
+       {
+               ERROR("couldn't read the requested number of bytes from PRESTO (%i < %i)", *bytes_read, size);
+               return ERROR_JTAG_DEVICE_ERROR;
+       }
+       
+       return ERROR_OK;
+}
+
+#if BUILD_PRESTO_FTD2XX == 1
+int presto_open_ftd2xx(char *req_serial)
 {
        int i;
-       int result;
        DWORD numdevs;
        DWORD vidpid;
        char devname[FT_DEVICE_NAME_LEN];
@@ -144,91 +222,205 @@ int presto_open(char *req_serial)
        BYTE presto_data;
        unsigned long ftbytes;
 
-       presto->handle=INVALID_HANDLE_VALUE;
-
-       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->jtag_tms=0;
-       presto->jtag_tck=0;
-       presto->jtag_tdi_data=0;
-       presto->jtag_tdi_count=0;
+       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");
+               exit(-1);
+       }
+#endif
 
-       if (FT_ListDevices(&numdevs, NULL, FT_LIST_NUMBER_ONLY)!=FT_OK) return PRST_ERR;
-       for (i=0; i<numdevs; i++)
+       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;
+       }
+       
+       for (i = 0; i < numdevs; i++)
        {
-               if (FT_Open(i, &(presto->handle))!=FT_OK) continue;
-               if (FT_GetDeviceInfo(presto->handle,&device,&vidpid,presto->serial,devname,NULL)==FT_OK)
+               if (FT_Open(i, &(presto->handle)) != FT_OK)
                {
-                       if (vidpid==PRESTO_VID_PID && (req_serial==NULL || !strcmp(presto->serial,req_serial)))
+                       ERROR("FT_Open failed: %i", (int)presto->status);
+                       continue;
+               }
+                       
+               if (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;
                }
+               
                FT_Close(presto->handle);
-               presto->handle=INVALID_HANDLE_VALUE;
+               presto->handle = (FT_HANDLE)INVALID_HANDLE_VALUE;
        }
 
-       if (presto->handle==INVALID_HANDLE_VALUE) return PRST_ERR;
-
-       if ((presto->status=FT_SetLatencyTimer(presto->handle,1))!=FT_OK) return PRST_ERR;
-       if ((presto->status=FT_SetTimeouts(presto->handle,100,0))!=FT_OK) return PRST_ERR;
-       if ((presto->status=FT_Purge(presto->handle, FT_PURGE_TX|FT_PURGE_RX))!=FT_OK) return PRST_ERR;
+       if (presto->handle == (FT_HANDLE)INVALID_HANDLE_VALUE)
+               return ERROR_JTAG_INIT_FAILED;
+       if ((presto->status = FT_SetLatencyTimer(presto->handle, 1)) != FT_OK)
+               return ERROR_JTAG_INIT_FAILED;
+       if ((presto->status = FT_SetTimeouts(presto->handle, 100, 0)) != FT_OK)
+               return ERROR_JTAG_INIT_FAILED;
+       if ((presto->status = FT_Purge(presto->handle, FT_PURGE_TX | FT_PURGE_RX)) != FT_OK)
+               return ERROR_JTAG_INIT_FAILED;
 
-       presto_data=0xD0;
-       if ((presto->status=FT_Write(presto->handle,&presto_data,1,&ftbytes))!=FT_OK) return PRST_ERR;
-       if ((presto->status=FT_Read(presto->handle,&presto_data,1,&ftbytes))!=FT_OK) return PRST_ERR;
+       presto_data = 0xD0;
+       if ((presto->status = FT_Write(presto->handle, &presto_data, 1, &ftbytes)) != FT_OK)
+               return ERROR_JTAG_INIT_FAILED;
+       if ((presto->status = FT_Read(presto->handle, &presto_data, 1, &ftbytes)) != FT_OK)
+               return ERROR_JTAG_INIT_FAILED;
 
        if (ftbytes!=1)
        {
-               if ((presto->status=FT_SetBitMode(presto->handle,0x80,1))!=FT_OK) return PRST_ERR;
-               if ((presto->status=FT_Purge(presto->handle, FT_PURGE_TX|FT_PURGE_RX))!=FT_OK) return PRST_ERR ;
-               if ((presto->status=FT_SetBaudRate(presto->handle,9600))!=FT_OK) return PRST_ERR;
-
-               presto_data=0;
-               for (i=0; i<4*62; i++)
-                       if ((presto->status=FT_Write(presto->handle,&presto_data,1,&ftbytes))!=FT_OK) return PRST_ERR;
+               if ((presto->status = FT_SetBitMode(presto->handle, 0x80, 1)) != FT_OK)
+                       return ERROR_JTAG_INIT_FAILED;
+               if ((presto->status = FT_Purge(presto->handle, FT_PURGE_TX | FT_PURGE_RX)) != FT_OK)
+                       return ERROR_JTAG_INIT_FAILED ;
+               if ((presto->status = FT_SetBaudRate(presto->handle, 9600)) != FT_OK)
+                       return ERROR_JTAG_INIT_FAILED;
+
+               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;
 
                usleep(100000);
 
-               if ((presto->status=FT_SetBitMode(presto->handle,0x00,0))!=FT_OK) return PRST_ERR;
-               if ((presto->status=FT_Purge(presto->handle, FT_PURGE_TX|FT_PURGE_RX))!=FT_OK) return PRST_ERR;
-
-               presto_data=0xD0;
-               if ((presto->status=FT_Write(presto->handle,&presto_data,1,&ftbytes))!=FT_OK) return PRST_ERR;
-               if ((presto->status=FT_Read(presto->handle,&presto_data,1,&ftbytes))!=FT_OK) return PRST_ERR;
-               if (ftbytes!=1) return PRST_ERR;
+               if ((presto->status = FT_SetBitMode(presto->handle, 0x00, 0)) != FT_OK)
+                       return ERROR_JTAG_INIT_FAILED;
+               if ((presto->status = FT_Purge(presto->handle, FT_PURGE_TX | FT_PURGE_RX)) != FT_OK)
+                       return ERROR_JTAG_INIT_FAILED;
+
+               presto_data = 0xD0;
+               if ((presto->status = FT_Write(presto->handle, &presto_data, 1, &ftbytes)) != FT_OK)
+                       return ERROR_JTAG_INIT_FAILED;
+               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;
        }
 
-       if ((presto->status=FT_SetTimeouts(presto->handle,0,0))!=FT_OK) return PRST_ERR;
+       if ((presto->status = FT_SetTimeouts(presto->handle, 0, 0)) != FT_OK)
+               return ERROR_JTAG_INIT_FAILED;
+
+       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;
+
+       return ERROR_OK;
+}
+
+#elif BUILD_PRESTO_LIBFTDI == 1
+int presto_open_libftdi(char *req_serial)
+{
+       u8 presto_data;
+       u32 ftbytes;
+               
+       DEBUG("searching for presto JTAG interface using libftdi");
+
+       /* 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;
+       }
+       
+       if (ftdi_usb_reset(&presto->ftdic) < 0)
+       {
+               ERROR("unable to reset presto device");
+               return ERROR_JTAG_INIT_FAILED;
+       }
 
-       presto->status=FT_Write(presto->handle,&presto_init_seq,sizeof(presto_init_seq),&ftbytes);
-       if (presto->status!=FT_OK) return PRST_ERR;
-       if (ftbytes!=sizeof(presto_init_seq)) return PRST_TIMEOUT;
+       if (ftdi_set_latency_timer(&presto->ftdic, 1) < 0)
+       {
+               ERROR("unable to set latency timer");
+               return ERROR_JTAG_INIT_FAILED;
+       }
 
-       return PRST_OK;
+       if (ftdi_usb_purge_buffers(&presto->ftdic) < 0)
+       {
+               ERROR("unable to purge presto buffer");
+               return ERROR_JTAG_INIT_FAILED;
+       }
+       
+       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;
+       
+       return ERROR_OK;
 }
+#endif /* BUILD_PRESTO_LIBFTDI == 1 */
 
+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->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;
+
+#if BUILD_PRESTO_FTD2XX == 1
+       return presto_open_ftd2xx(req_serial);
+#elif BUILD_PRESTO_LIBFTDI == 1
+       return presto_open_libftdi(req_serial);
+#endif
+}
 
 int presto_close(void)
 {
-       unsigned long ftbytes;
 
-       int result=PRST_OK;
+       int result = ERROR_OK;
 
-       if (presto->handle==INVALID_HANDLE_VALUE) return result;
+#if BUID_PRESTO_FTD2XX == 1
+       unsigned long ftbytes;
 
-       presto->status=FT_Write(presto->handle,&presto_init_seq,sizeof(presto_init_seq),&ftbytes);
-       if (presto->status!=FT_OK) result=PRST_ERR;
-       if (ftbytes!=sizeof(presto_init_seq)) result=PRST_TIMEOUT;
+       if (presto->handle == (FT_HANDLE)INVALID_HANDLE_VALUE)
+               return result;
 
-       if ((presto->status=FT_SetLatencyTimer(presto->handle,16))!=FT_OK) result=PRST_ERR;
+       presto->status = FT_Write(presto->handle, &presto_init_seq, sizeof(presto_init_seq), &ftbytes);
+       if (presto->status != FT_OK)
+               result = PRST_ERR;
+       if (ftbytes != sizeof(presto_init_seq))
+               result = PRST_TIMEOUT;
 
-       if ((presto->status=FT_Close(presto->handle))!=FT_OK) result=PRST_ERR;
-       else presto->handle=INVALID_HANDLE_VALUE;
+       if ((presto->status = FT_SetLatencyTimer(presto->handle, 16)) != FT_OK)
+               result = PRST_ERR;
+
+       if ((presto->status = FT_Close(presto->handle)) != FT_OK)
+               result = PRST_ERR;
+       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)
+       {
+               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);
+       
+#endif
 
        return result;
 }
@@ -236,77 +428,92 @@ int presto_close(void)
 
 int presto_flush(void)
 {
-       unsigned long ftbytes;
+       u32 ftbytes;
 
-       if (presto->buff_out_pos==0) return PRST_OK;
-       if (presto->status!=FT_OK) return PRST_ERR;
+       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)
+#endif
+               return ERROR_JTAG_DEVICE_ERROR;
 
-       if ((presto->status=FT_Write(presto->handle, presto->buff_out, presto->buff_out_pos, &ftbytes))!=FT_OK)
+
+       if (presto_write(presto->buff_out, presto->buff_out_pos, &ftbytes) != ERROR_OK)
        {
-               presto->buff_out_pos=0;
-               return PRST_ERR;
+               presto->buff_out_pos = 0;
+               return ERROR_JTAG_DEVICE_ERROR;
        }
 
-       presto->total_out+=ftbytes;
+       presto->total_out += ftbytes;
 
-       if (presto->buff_out_pos!=ftbytes)
+       if (presto->buff_out_pos != ftbytes)
        {
-               presto->buff_out_pos=0;
-               return PRST_TIMEOUT;
+               presto->buff_out_pos = 0;
+               return ERROR_JTAG_DEVICE_ERROR;
        }
 
-       presto->buff_out_pos=0;
+       presto->buff_out_pos = 0;
 
-       if (presto->buff_in_exp==0) return PRST_OK;
+       if (presto->buff_in_exp == 0)
+               return ERROR_OK;
 
-       presto->buff_in_pos=0;
-       presto->buff_in_len=0;
+       presto->buff_in_pos = 0;
+       presto->buff_in_len = 0;
 
-       if ((presto->status=FT_Read(presto->handle, presto->buff_in, presto->buff_in_exp, &ftbytes))!=FT_OK)
+       if (presto_read(presto->buff_in, presto->buff_in_exp, &ftbytes) != ERROR_OK)
        {
-               presto->buff_in_exp=0;
-               return PRST_ERR;
+               presto->buff_in_exp = 0;
+               return ERROR_JTAG_DEVICE_ERROR;
        }
 
-       presto->total_in+=ftbytes;
+       presto->total_in += ftbytes;
 
-       if (ftbytes!=presto->buff_in_exp)
+       if (ftbytes != presto->buff_in_exp)
        {
-               presto->buff_in_exp=0;
-               return PRST_TIMEOUT;
+               presto->buff_in_exp = 0;
+               return ERROR_JTAG_DEVICE_ERROR;
        }
 
-       presto->buff_in_len=presto->buff_in_exp;
-       presto->buff_in_exp=0;
+       presto->buff_in_len = presto->buff_in_exp;
+       presto->buff_in_exp = 0;
 
-       return PRST_OK;
+       return ERROR_OK;
 }
 
 
 int presto_sendbyte(int data)
 {
-       if (data==EOF) return presto_flush();
+       if (data == EOF) return presto_flush();
 
        if (presto->buff_out_pos < BUFFER_SIZE)
        {
-               presto->buff_out[presto->buff_out_pos++]=(BYTE)data;
-               if (((data&0xC0)==0x40) || ((data&0xD0)==0xD0))
+               presto->buff_out[presto->buff_out_pos++] = (u8)data;
+               if (((data & 0xC0) == 0x40) || ((data & 0xD0)== 0xD0))
                        presto->buff_in_exp++;
        }
-       else return PRST_ERR;
+       else
+               return ERROR_JTAG_DEVICE_ERROR;
 
-       if (presto->buff_out_pos >= BUFFER_SIZE) return presto_flush();
-       return PRST_OK;
+       if (presto->buff_out_pos >= BUFFER_SIZE)
+               return presto_flush();
+       
+       return ERROR_OK;
 }
 
 
 int presto_getbyte(void)
 {
-       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++];
 
-       if (presto->buff_in_exp==0) return -1;
-       if (presto_flush()!=PRST_OK) return -1;
+       if (presto->buff_in_exp == 0)
+               return -1;
+       
+       if (presto_flush() != ERROR_OK)
+               return -1;
 
        if (presto->buff_in_pos<presto->buff_in_len)
                return presto->buff_in[presto->buff_in_pos++];
@@ -322,46 +529,55 @@ int presto_bitq_out(int tms, int tdi, int tdo_req)
 {
        unsigned char cmdparam;
 
-       if (presto->jtag_tck==0)
+       if (presto->jtag_tck == 0)
        {
                presto_sendbyte(0xA4);
-               presto->jtag_tck=1;
+               presto->jtag_tck = 1;
        }
 
-       else if (!tdo_req && tms==presto->jtag_tms)
+       else if (!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;
-               if (++presto->jtag_tdi_count==4)
+               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->jtag_tdi_data |= (presto->jtag_tdi_count - 1) << 4;
                        presto_sendbyte(presto->jtag_tdi_data);
-                       presto->jtag_tdi_count=0;
+                       presto->jtag_tdi_count = 0;
                }
                return 0;
        }
 
        if (presto->jtag_tdi_count)
        {
-               presto->jtag_tdi_data|=(presto->jtag_tdi_count-1)<<4;
+               presto->jtag_tdi_data |= (presto->jtag_tdi_count - 1) << 4;
                presto_sendbyte(presto->jtag_tdi_data);
-               presto->jtag_tdi_count=0;
+               presto->jtag_tdi_count = 0;
        }
 
-       if (tdi) cmdparam=0x0B;
-       else cmdparam=0x0A;
+       if (tdi)
+               cmdparam = 0x0B;
+       else
+               cmdparam = 0x0A;
 
-       presto_sendbyte(0xC0|cmdparam);
+       presto_sendbyte( 0xC0 | cmdparam);
 
-       if (tms!=presto->jtag_tms)
+       if (tms != presto->jtag_tms)
        {
-               if (tms) presto_sendbyte(0xEC);
-               else presto_sendbyte(0xE8);
-               presto->jtag_tms=tms;
+               if (tms)
+                       presto_sendbyte(0xEC);
+               else
+                       presto_sendbyte(0xE8);
+               presto->jtag_tms = tms;
        }
 
-       if (tdo_req) presto_sendbyte(0xD4|cmdparam);
-       else presto_sendbyte(0xC4|cmdparam);
+       if (tdo_req)
+               presto_sendbyte(0xD4 | cmdparam);
+       else
+               presto_sendbyte(0xC4|cmdparam);
 
        return 0;
 }
@@ -371,13 +587,13 @@ int presto_bitq_flush(void)
 {
        if (presto->jtag_tdi_count)
        {
-               presto->jtag_tdi_data|=(presto->jtag_tdi_count-1)<<4;
+               presto->jtag_tdi_data |= (presto->jtag_tdi_count - 1) << 4;
                presto_sendbyte(presto->jtag_tdi_data);
-               presto->jtag_tdi_count=0;
+               presto->jtag_tdi_count = 0;
        }
 
        presto_sendbyte(0xCA);
-       presto->jtag_tck=0;
+       presto->jtag_tck = 0;
 
        presto_sendbyte(0xA0);
 
@@ -387,14 +603,16 @@ int presto_bitq_flush(void)
 
 int presto_bitq_in_rdy(void)
 {
-       if (presto->buff_in_pos>=presto->buff_in_len) return 0;
+       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)
 {
-       if (presto->buff_in_pos>=presto->buff_in_len) return -1;
+       if (presto->buff_in_pos>=presto->buff_in_len)
+               return -1;
        if (presto->buff_in[presto->buff_in_pos++]&0x08) return 1;
        return 0;
 }
@@ -404,15 +622,16 @@ int presto_bitq_sleep(unsigned long us)
 {
        long waits;
 
-       if (us>100000)
+       if (us > 100000)
        {
                presto_bitq_flush();
                jtag_sleep(us);
                return 0;
        }
 
-       waits=us/170+2;
-       while (waits--) presto_sendbyte(0x80);
+       waits = us / 170 + 2;
+       while (waits--)
+               presto_sendbyte(0x80);
 
        return 0;
 }
@@ -422,10 +641,12 @@ int presto_bitq_reset(int trst, int srst)
 {
        unsigned char cmd;
 
-       cmd=0xE8;
-       if (presto->jtag_tms) cmd|=0x04;
+       cmd = 0xE8;
+       if (presto->jtag_tms)
+               cmd |= 0x04;
 
-       if (trst || srst) cmd|=0x02;
+       if (trst || srst)
+               cmd |= 0x02;
 
        presto_sendbyte(cmd);
        return 0;
@@ -434,11 +655,26 @@ int presto_bitq_reset(int trst, int srst)
 
 /* -------------------------------------------------------------------------- */
 
+char *presto_speed_text[4] =
+{
+       "3 MHz",
+       "1.5 MHz",
+       "750 kHz",
+       "93.75 kHz"
+};
 
 int presto_jtag_speed(int speed)
 {
-       jtag_speed=speed;
-       return ERROR_OK;
+
+       if ((speed < 0) || (speed > 3))
+       {
+               INFO("valid speed values: 0 (3 MHz), 1 (1.5 MHz), 2 (750 kHz) and 3 (93.75 kHz)");
+               return ERROR_INVALID_ARGUMENTS;
+       }
+
+       jtag_speed = speed;
+       INFO("setting speed to %d, max. TCK freq. is %s", speed, presto_speed_text[speed]);
+       return presto_sendbyte(0xA8 | speed);
 }
 
 
@@ -448,7 +684,8 @@ int presto_handle_serial_command(struct command_context_s *cmd_ctx, char *cmd, c
 {
        if (argc == 1)
        {
-               if (presto_serial) free(presto_serial);
+               if (presto_serial)
+                       free(presto_serial);
                presto_serial = strdup(args[0]);
        }
        else
@@ -470,16 +707,21 @@ int presto_jtag_register_commands(struct command_context_s *cmd_ctx)
 
 int presto_jtag_init(void)
 {
-       if (presto_open(presto_serial)!=0)
+       if (presto_open(presto_serial) != ERROR_OK)
        {
                presto_close();
-               if (presto_serial!=NULL) ERROR("Cannot open PRESTO, serial number %s", presto_serial);
-               else ERROR("Cannot open PRESTO");
+               if (presto_serial != NULL)
+                       ERROR("Cannot open PRESTO, serial number '%s'", presto_serial);
+               else
+                       ERROR("Cannot open PRESTO");
                return ERROR_JTAG_INIT_FAILED;
        }
-       INFO("PRESTO open, serial number %s", presto->serial);
+       INFO("PRESTO open, serial number '%s'", presto->serial);
+       
+       /* use JTAG speed setting from configuration file */
+       presto_jtag_speed(jtag_speed);
        
-       bitq_interface=&presto_bitq;
+       bitq_interface = &presto_bitq;
        return ERROR_OK;
 }
 
@@ -493,7 +735,7 @@ int presto_jtag_quit(void)
        if (presto_serial)
        {
                free(presto_serial);
-               presto_serial=NULL;
+               presto_serial = NULL;
        }
 
        return ERROR_OK;