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hosted/jlink: rewrite frequency commands with proper interface handling
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@perigoso @rg-silva
perigoso authored and rg-silva committed Jul 27, 2023
1 parent 61ad322 commit 8872d2a
Showing 1 changed file with 106 additions and 39 deletions.
145 changes: 106 additions & 39 deletions src/platforms/hosted/jlink.c
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Original file line number Diff line number Diff line change
Expand Up @@ -48,9 +48,12 @@ typedef struct jlink {
uint32_t hw_version; /* Hardware version */
uint32_t capabilities; /* Bitfield of supported capabilities */
uint32_t available_interfaces; /* Bitfield of available interfaces */
uint32_t base_frequency; /* Base frequency of the interface */
uint16_t min_divisor; /* Minimum divisor for the interface */
uint16_t current_divisor; /* Current divisor for the interface */

struct jlink_interface_frequency {
uint32_t base; /* Base frequency of the interface */
uint16_t min_divisor; /* Minimum divisor for the interface */
uint16_t current_divisor; /* Current divisor for the interface */
} interface_frequency[JLINK_INTERFACE_MAX];
} jlink_s;

jlink_s jlink;
Expand Down Expand Up @@ -382,53 +385,116 @@ static bool jlink_get_interfaces(void)
return true;
}

static bool jlink_get_interface_frequency(void)
static bool jlink_get_interface_frequency(const uint8_t interface)
{
/*
* Fixme: this is not strictly correct, the reported base frequency and min divisor depend on the
* interface selected, but we don't know which one is selected at this point, we are assuming JTAG
* and that JTAG is the only interface that supports frequency info/set.
* Unfortunately, this does not look like it's documented on the docs we have access to.
*/

if (jlink.capabilities & JLINK_CAPABILITY_INTERFACE_FREQUENCY) {
uint8_t buffer[6U];
if (!jlink_simple_query(JLINK_CMD_INTERFACE_GET_BASE_FREQUENCY, buffer, sizeof(buffer)))
if (!(jlink.capabilities & JLINK_CAPABILITY_INTERFACE_FREQUENCY)) {
DEBUG_WARN("J-Link does not support interface frequency commands\n");
return false;
}

/* If the requested interface is invalid, bail out */
if (!jlink_interface_available(interface))
return false;

/* If the base frequency is non-zero, we've already read the frequency info for the requested interface and can skip the query */
if (jlink.interface_frequency[interface].base != 0U)
return true;

/* Get the selected interface */
const uint8_t selected_interface = jlink_selected_interface();

if (selected_interface != interface) {
/* If the selected interface doesn't match the requested interface, select it, let's hope this doesn't mess something up elsewhere */
DEBUG_WARN("Trying to get frequency for interface %s but it is not selected, selecting it\n",
jlink_interface_to_string(interface));

/* select the requested interface */
if (!jlink_select_interface(interface))
return false;
}

/* Get the frequency info for the selected interface */
uint8_t buffer[6U];
if (!jlink_simple_query(JLINK_CMD_INTERFACE_GET_BASE_FREQUENCY, buffer, sizeof(buffer)))
return false;

struct jlink_interface_frequency *const interface_frequency = &jlink.interface_frequency[interface];

jlink.base_frequency = read_le4(buffer, JLINK_INTERFACE_BASE_FREQUENCY_OFFSET);
jlink.min_divisor = read_le2(buffer, JLINK_INTERFACE_MIN_DIV_OFFSET);
jlink.current_divisor = jlink.min_divisor;
interface_frequency->base = read_le4(buffer, JLINK_INTERFACE_BASE_FREQUENCY_OFFSET);
interface_frequency->min_divisor = read_le2(buffer, JLINK_INTERFACE_MIN_DIV_OFFSET);

DEBUG_INFO("Base frequency: %uHz\n\tMinimum divisor: %u\n", jlink.base_frequency, jlink.min_divisor);
} else
DEBUG_WARN("J-Link does not support frequency info command\n");
/* This is an assumption, if the J-Link was configured before we started, this may not be true, but we have no way to know */
interface_frequency->current_divisor = interface_frequency->min_divisor;

DEBUG_INFO("%s interface frequency:\n\tBase frequency: %uHz\n\tMinimum divisor: %u\n",
jlink_interface_to_string(interface), interface_frequency->base, interface_frequency->min_divisor);

// Restoring the selected interface seemed to cause issues sometimes (unsure if culprit)
// so we don't do it for now, it didn't seem to be necessary, saving in case it proves to be necessary later
// if (selected_interface != interface) {
// /* If the selected interface didn't match the requested interface, restore the selected interface */
// DEBUG_WARN("Restoring selected interface to %s\n", jlink_interface_to_string(selected_interface));

// /* select the requested interface, we don't consider this a critical failure, as we got what we wanted */
// if (!jlink_select_interface(selected_interface))
// DEBUG_ERROR("Failed to restore selected interface to %s\n", jlink_interface_to_string(selected_interface));
// }

return true;
}

bool jlink_set_jtag_frequency(const uint32_t frequency)
bool jlink_set_interface_frequency(const uint8_t interface, const uint32_t frequency)
{
/* Fixme: see note on jlink_get_interface_frequency */
if (!(jlink.capabilities & JLINK_CAPABILITY_INTERFACE_FREQUENCY)) {
DEBUG_WARN("J-Link does not support interface frequency command\n");
return false;
}

/* Get the selected interface */
const uint8_t selected_interface = jlink_selected_interface();

if (selected_interface != interface) {
/* If the selected interface doesn't match the requested interface, select it, let's hope this doesn't mess something up elsewhere */
DEBUG_WARN("Trying to set frequency for interface %s but it is not selected, selecting it\n",
jlink_interface_to_string(interface));

if (!(jlink.capabilities & JLINK_CAPABILITY_INTERFACE_FREQUENCY))
/* select the requested interface */
if (!jlink_select_interface(interface))
return false;
}

/* Ensure we have the frequency info for the selected interface */
if (!jlink_get_interface_frequency(interface))
return false;

struct jlink_interface_frequency *const interface_frequency = &jlink.interface_frequency[interface];

/* Find the divisor that gets us closest to the requested frequency */
uint16_t divisor = (jlink.base_frequency + frequency - 1U) / frequency;
uint16_t divisor = (interface_frequency->base + frequency - 1U) / frequency;

/* Bound the divisor to the min divisor */
if (divisor < jlink.min_divisor)
divisor = jlink.min_divisor;
if (divisor < interface_frequency->min_divisor)
divisor = interface_frequency->min_divisor;

/* Get the approximate frequency we'll actually be running at, convert to kHz in the process */
const uint16_t frequency_khz = (jlink.base_frequency / jlink.current_divisor) / 1000U;
const uint16_t frequency_khz = (interface_frequency->base / interface_frequency->current_divisor) / 1000U;

if (!jlink_simple_request_16(JLINK_CMD_INTERFACE_SET_FREQUENCY_KHZ, frequency_khz, NULL, 0))
return false;

/* Update the current divisor for frquency calculations */
jlink.current_divisor = divisor;
/* Update the current divisor for frequency calculations */
interface_frequency->current_divisor = divisor;

// Restoring the selected interface seemed to cause issues sometimes (unsure if culprit)
// so we don't do it for now, it didn't seem to be necessary, saving in case it proves to be necessary later
// if (selected_interface != interface) {
// /* If the selected interface didn't match the requested interface, restore the selected interface */
// DEBUG_WARN("Restoring selected interface to %s\n", jlink_interface_to_string(selected_interface));

// /* select the requested interface, we don't consider this a critical failure, as we got what we wanted */
// if (!jlink_select_interface(selected_interface))
// DEBUG_ERROR("Failed to restore selected interface to %s\n", jlink_interface_to_string(selected_interface));
// }

return true;
}
Expand Down Expand Up @@ -501,8 +567,7 @@ bool jlink_init(void)
libusb_close(info.usb_link->device_handle);
return false;
}
if (!jlink_get_capabilities() || !jlink_get_version() || !jlink_get_interfaces() ||
!jlink_get_interface_frequency()) {
if (!jlink_get_capabilities() || !jlink_get_version() || !jlink_get_interfaces()) {
DEBUG_ERROR("Failed to read J-Link information\n");
libusb_release_interface(info.usb_link->device_handle, info.usb_link->interface);
libusb_close(info.usb_link->device_handle);
Expand Down Expand Up @@ -547,22 +612,24 @@ bool jlink_nrst_get_val(void)

void jlink_max_frequency_set(const uint32_t frequency)
{
/* Fixme: see note on jlink_get_interface_frequency */
const uint8_t bmda_interface = info.is_jtag ? JLINK_INTERFACE_JTAG : JLINK_INTERFACE_SWD;

if (!(jlink.capabilities & JLINK_CAPABILITY_INTERFACE_FREQUENCY) || !info.is_jtag)
return;

jlink_set_jtag_frequency(frequency);
if (!jlink_set_interface_frequency(bmda_interface, frequency))
DEBUG_ERROR("Failed to set J-Link %s interface frequency\n", jlink_interface_to_string(bmda_interface));
}

uint32_t jlink_max_frequency_get(void)
{
/* Fixme: see note on jlink_get_interface_frequency */
const uint8_t bmda_interface = info.is_jtag ? JLINK_INTERFACE_JTAG : JLINK_INTERFACE_SWD;

if (!(jlink.capabilities & JLINK_CAPABILITY_INTERFACE_FREQUENCY) || !info.is_jtag)
/* Ensure we have the frequency info for the requested interface */
if (!jlink_get_interface_frequency(bmda_interface)) {
DEBUG_ERROR("No frequency info available for interface %s\n", jlink_interface_to_string(bmda_interface));
return FREQ_FIXED;
}

return jlink.base_frequency / jlink.current_divisor;
struct jlink_interface_frequency *const interface_frequency = &jlink.interface_frequency[bmda_interface];
return interface_frequency->base / interface_frequency->current_divisor;
}

bool jlink_target_set_power(const bool power)
Expand Down

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