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/* chain_commands.c -- JTAG protocol bridge between GDB and Advanced debug module.
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/* chain_commands.c -- JTAG protocol bridge between GDB and Advanced debug module.
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Copyright(C) Nathan Yawn, nyawn@opencores.net
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Copyright(C) 2008 - 2010 Nathan Yawn, nyawn@opencores.net
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based on code from jp2 by Marko Mlinar, markom@opencores.org
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based on code from jp2 by Marko Mlinar, markom@opencores.org
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This file contains functions which perform mid-level transactions
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This file contains functions which perform mid-level transactions
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on a JTAG, such as setting a value in the TAP IR
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on a JTAG, such as setting a value in the TAP IR
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or doing a burst write on the JTAG chain.
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or doing a burst write on the JTAG chain.
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// There is no way to automatically determine the length of the IR registers -
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// There is no way to automatically determine the length of the IR registers -
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// this must be read from a BSDL file, if IDCODE is supported.
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// this must be read from a BSDL file, if IDCODE is supported.
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// When IDCODE is not supported, IR length of the target device must be entered on the command line.
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// When IDCODE is not supported, IR length of the target device must be entered on the command line.
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#define ALLOC_SIZE 64
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#define ALLOC_SIZE 64
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#define MAX_DEVICES 1024
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int jtag_enumerate_chain(uint32_t **id_array, int *num_devices)
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int jtag_enumerate_chain(uint32_t **id_array, int *num_devices)
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{
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{
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uint32_t invalid_code = 0x7f; // Shift this out, we know we're done when we get it back
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uint32_t invalid_code = 0x7f; // Shift this out, we know we're done when we get it back
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const unsigned int done_code = 0x3f; // invalid_code is altered, we keep this for comparison (minus the start bit)
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const unsigned int done_code = 0x3f; // invalid_code is altered, we keep this for comparison (minus the start bit)
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int devindex = 0; // which device we are currently trying to detect
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int devindex = 0; // which device we are currently trying to detect
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printf("Enumerating JTAG chain...\n");
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printf("Enumerating JTAG chain...\n");
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// Putting a limit on the # of devices supported has the useful side effect
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// Putting a limit on the # of devices supported has the useful side effect
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// of insuring we still exit in error cases (we never get the 0x7f manuf. id)
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// of insuring we still exit in error cases (we never get the 0x7f manuf. id)
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while(devindex < max_devices) {
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while(devindex < MAX_DEVICES) {
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// get 1 bit. 0 = BYPASS, 1 = start of IDCODE
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// get 1 bit. 0 = BYPASS, 1 = start of IDCODE
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err |= jtag_read_write_bit(invalid_code&0x01, &start_bit);
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err |= jtag_read_write_bit(invalid_code&0x01, &start_bit);
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invalid_code >>= 1;
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invalid_code >>= 1;
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if(start_bit == 0) {
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if(start_bit == 0) {
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if(err) // Don't try to keep probing if we get a comm. error
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if(err) // Don't try to keep probing if we get a comm. error
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return err;
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return err;
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}
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}
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if(devindex >= max_devices)
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if(devindex >= MAX_DEVICES)
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printf("WARNING: maximum supported devices on JTAG chain (%i) exceeded.\n", max_devices);
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printf("WARNING: maximum supported devices on JTAG chain (%i) exceeded.\n", MAX_DEVICES);
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// Put in IDLE mode
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// Put in IDLE mode
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err |= jtag_write_bit(TMS); /* EXIT1_DR */
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err |= jtag_write_bit(TMS); /* EXIT1_DR */
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err |= jtag_write_bit(TMS); /* UPDATE_DR */
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err |= jtag_write_bit(TMS); /* UPDATE_DR */
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err |= jtag_write_bit(0); /* IDLE */
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err |= jtag_write_bit(0); /* IDLE */
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