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parport: add support for the jtag_khz command.

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Add the khz and speed_div functions to the parport interface driver.
Add the parport_toggling_time function that tells the parport driver
how long (in nanoseconds) it takes for the hardware to toggle TCK.

[dbrownell@users.sourceforge.net: tweak doc for clarity, mention
multimeter, and whitespace fixes]

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
This commit is contained in:
Jonas Horberg
2009-11-12 12:39:37 -08:00
committed by David Brownell
parent 5723e54fa9
commit de735d375b
2 changed files with 100 additions and 8 deletions
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72
src/jtag/parport.c
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@@ -105,6 +105,8 @@ static cable_t cables[] =
static char* parport_cable = NULL;
static uint16_t parport_port;
static int parport_exit = 0;
static uint32_t parport_toggling_time_ns = 1000;
static int wait_states;
/* interface variables
*/
@@ -152,7 +154,7 @@ static __inline__ void parport_write_data(void)
static void parport_write(int tck, int tms, int tdi)
{
int i = jtag_get_speed() + 1;
int i = wait_states + 1;
if (tck)
dataport_value |= cable->TCK_MASK;
@@ -204,6 +206,26 @@ static void parport_led(int on)
static int parport_speed(int speed)
{
wait_states = speed;
return ERROR_OK;
}
static int parport_khz(int khz, int* jtag_speed)
{
if (khz == 0) {
LOG_DEBUG("RCLK not supported");
return ERROR_FAIL;
}
*jtag_speed = 499999 / (khz * parport_toggling_time_ns);
return ERROR_OK;
}
static int parport_speed_div(int speed, int* khz)
{
uint32_t denominator = (speed + 1) * parport_toggling_time_ns;
*khz = (499999 + denominator) / denominator;
return ERROR_OK;
}
@@ -364,6 +386,8 @@ static int parport_init(void)
bitbang_interface = &parport_bitbang;
wait_states = jtag_get_speed();
return ERROR_OK;
}
@@ -438,6 +462,32 @@ static int parport_handle_write_on_exit_command(struct command_context_s *cmd_ct
return ERROR_OK;
}
static int
parport_handle_parport_toggling_time_command(struct command_context_s *cmd_ctx,
char *cmd, char **args, int argc)
{
if (argc == 1) {
uint32_t ns;
int retval = parse_u32(args[0], &ns);
if (ERROR_OK != retval)
return retval;
if (ns == 0) {
LOG_ERROR("0 ns is not a valid parport toggling time");
return ERROR_FAIL;
}
parport_toggling_time_ns = ns;
wait_states = jtag_get_speed();
}
command_print(cmd_ctx, "parport toggling time = %" PRIu32 " ns",
parport_toggling_time_ns);
return ERROR_OK;
}
static int parport_register_commands(struct command_context_s *cmd_ctx)
{
register_command(cmd_ctx, NULL, "parport_port",
@@ -455,14 +505,20 @@ static int parport_register_commands(struct command_context_s *cmd_ctx)
"configure the parallel driver to write "
"a known value to the parallel interface");
register_command(cmd_ctx, NULL, "parport_toggling_time",
parport_handle_parport_toggling_time_command, COMMAND_ANY,
"time <ns> it takes for the hardware to toggle TCK");
return ERROR_OK;
}
jtag_interface_t parport_interface = {
.name = "parport",
.register_commands = &parport_register_commands,
.init = &parport_init,
.quit = &parport_quit,
.speed = &parport_speed,
.execute_queue = &bitbang_execute_queue,
};
.name = "parport",
.register_commands = parport_register_commands,
.init = parport_init,
.quit = parport_quit,
.khz = parport_khz,
.speed_div = parport_speed_div,
.speed = parport_speed,
.execute_queue = bitbang_execute_queue,
};