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swd: After write low_access, always append 8 clk to move data through SW-DP. 

Especially needed when leaving the debugger or during debug unit power-up.

ARM Debug Interface Architecture Specification ADIv5.0 to ADIv5.2
tells to clock the data through SW-DP to either :
- immediate start a new transaction
- continue to drive idle cycles
- or clock at least 8 idle cycles

Implement last option to favour correctness over slight speed decrease

Implement only for adapters where we assemble the seq_out_parity in our code,
as on firmware, ftdi and jlink. Hopefully the high level adapters do it right.

Reverts 2c33cde63f and
cde7726b87
This commit is contained in:
Uwe Bonnes 2020-11-09 21:36:06 +01:00 committed by UweBonnes
parent 139e5d7e22
commit bf548e92c0
5 changed files with 46 additions and 45 deletions
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2
src/platforms/hosted/jlink.c
View File

@ -90,7 +90,7 @@ static void jlink_print_interfaces(bmp_info_t *info)
DEBUG_INFO(", %s available\n",
(other_interface == JLINK_IF_SWD) ? "SWD": "JTAG");
else
DEBUG_WARN(", %s not available\n",
DEBUG_INFO(", %s not available\n",
((res[0] + 1) == JLINK_IF_SWD) ? "JTAG": "SWD");
}

43
src/platforms/hosted/jlink_adiv5_swdp.c
View File

@ -249,20 +249,19 @@ static uint32_t jlink_adiv5_swdp_low_access(ADIv5_DP_t *dp, uint8_t RnW,
uint8_t res[8];
cmd[0] = CMD_HW_JTAG3;
cmd[1] = 0;
cmd[2] = 13;
cmd[2] = (RnW) ? 11 : 13; /* Turnaround inserted automatically? */
cmd[3] = 0;
cmd[4] = 0xff;
cmd[5] = 0xe3;
cmd[6] = request << 2;
cmd[7] = request >> 6;
cmd[5] = 0xfe;
cmd[6] = request;
cmd[7] = 0x00;
platform_timeout_set(&timeout, 2000);
do {
send_recv(info.usb_link, cmd, 8, res, 2);
send_recv(info.usb_link, NULL, 0, res, 1);
if (res[0] != 0)
send_recv(info.usb_link, NULL, 0, res + 2 , 1);
if (res[2] != 0)
raise_exception(EXCEPTION_ERROR, "Low access setup failed");
ack = res[1] >> 2;
ack &= 7;
ack = res[1] & 7;
} while (ack == SWDP_ACK_WAIT && !platform_timeout_is_expired(&timeout));
if (ack == SWDP_ACK_WAIT)
raise_exception(EXCEPTION_TIMEOUT, "SWDP ACK timeout");
@ -276,17 +275,15 @@ static uint32_t jlink_adiv5_swdp_low_access(ADIv5_DP_t *dp, uint8_t RnW,
if(ack != SWDP_ACK_OK) {
if (cl_debuglevel & BMP_DEBUG_TARGET)
DEBUG_WARN( "Protocol\n");
DEBUG_WARN( "Protocol %d\n", ack);
line_reset(&info);
return 0;
}
cmd[3] = 0;
/* Always prepend an idle cycle (SWDIO = 0)!*/
/* Always append 8 idle cycle (SWDIO = 0)!*/
if(RnW) {
memset(cmd + 4, 0, 10);
cmd[2] = 34;
cmd[2] = 33 + 2; /* 2 idle cycles */
cmd[8] = 0xfe;
cmd[13] = 0;
send_recv(info.usb_link, cmd, 14, res, 5);
send_recv(info.usb_link, NULL, 0, res + 5, 1);
if (res[5] != 0)
@ -294,19 +291,19 @@ static uint32_t jlink_adiv5_swdp_low_access(ADIv5_DP_t *dp, uint8_t RnW,
response = res[0] | res[1] << 8 | res[2] << 16 | res[3] << 24;
int parity = res[4] & 1;
int bit_count = __builtin_popcount (response) + parity;
if (bit_count & 1) /* Give up on parity error */
if (bit_count & 1) /* Give up on parity error */
raise_exception(EXCEPTION_ERROR, "SWDP Parity error");
} else {
cmd[2] = 35;
memset(cmd + 4, 0xff, 5);
cmd[ 9] = ((value << 2) & 0xfc);
cmd[10] = ((value >> 6) & 0xff);
cmd[11] = ((value >> 14) & 0xff);
cmd[12] = ((value >> 22) & 0xff);
cmd[13] = ((value >> 30) & 0x03);
cmd[2] = 33 + 8; /* 8 idle cycle to move data through SW-DP */
memset(cmd + 4, 0xff, 6);
cmd[10] = ((value >> 0) & 0xff);
cmd[11] = ((value >> 8) & 0xff);
cmd[12] = ((value >> 16) & 0xff);
cmd[13] = ((value >> 24) & 0xff);
int bit_count = __builtin_popcount(value);
cmd[13] |= ((bit_count & 1) ? 4 : 0);
send_recv(info.usb_link, cmd, 14, res, 5);
cmd[14] = bit_count & 1;
cmd[15] = 0;
send_recv(info.usb_link, cmd, 16, res, 6);
send_recv(info.usb_link, NULL, 0, res, 1);
if (res[0] != 0)
raise_exception(EXCEPTION_ERROR, "Low access write failed");

22
src/platforms/hosted/libftdi_swdptap.c
View File

@ -361,9 +361,19 @@ static void swdptap_seq_out(uint32_t MS, int ticks)
}
}
/* ARM Debug Interface Architecture Specification ADIv5.0 to ADIv5.2
* tells to clock the data through SW-DP to either :
* - immediate start a new transaction
* - continue to drive idle cycles
* - or clock at least 8 idle cycles
*
* Implement last option to favour correctness over
* slight speed decrease
*/
static void swdptap_seq_out_parity(uint32_t MS, int ticks)
{
int parity = __builtin_parity(MS & ((1LL << ticks) - 1)) & 1;
(void) ticks;
int parity = __builtin_parity(MS) & 1;
unsigned int index = 0;
swdptap_turnaround(SWDIO_STATUS_DRIVE);
if (do_mpsse) {
@ -373,26 +383,26 @@ static void swdptap_seq_out_parity(uint32_t MS, int ticks)
DI[2] = (MS >> 16) & 0xff;
DI[3] = (MS >> 24) & 0xff;
DI[4] = parity;
libftdi_jtagtap_tdi_tdo_seq(NULL, 0, DI, ticks + 1);
DI[5] = 0;
libftdi_jtagtap_tdi_tdo_seq(NULL, 0, DI, 32 + 1 + 8);
} else {
uint8_t cmd[32];
int steps = ticks;
while (steps) {
cmd[index++] = MPSSE_TMS_SHIFT;
cmd[index++] = 6;
if (steps >= 7) {
cmd[index++] = 6;
cmd[index++] = MS & 0x7f;
MS >>= 7;
steps -= 7;
} else {
cmd[index++] = steps - 1;
cmd[index++] = MS & 0x7f;
cmd[index++] = (MS & 0x7f) | (parity << 4);
steps = 0;
}
}
cmd[index++] = MPSSE_TMS_SHIFT;
cmd[index++] = 4;
cmd[index++] = 0;
cmd[index++] = parity;
libftdi_buffer_write(cmd, index);
}
}

20
src/target/adiv5_swdp.c
View File

@ -169,19 +169,17 @@ uint32_t firmware_swdp_low_access(ADIv5_DP_t *dp, uint8_t RnW,
raise_exception(EXCEPTION_ERROR, "SWDP Parity error");
} else {
swd_proc.swdptap_seq_out_parity(value, 32);
/* RM0377 Rev. 8 Chapter 27.5.4 for STM32L0x1 states:
* Because of the asynchronous clock domains SWCLK and HCLK,
* two extra SWCLK cycles are needed after a write transaction
* (after the parity bit) to make the write effective
* internally. These cycles should be applied while driving
* the line low (IDLE state)
* This is particularly important when writing the CTRL/STAT
* for a power-up request. If the next transaction (requiring
* a power-up) occurs immediately, it will fail.
/* ARM Debug Interface Architecture Specification ADIv5.0 to ADIv5.2
* tells to clock the data through SW-DP to either :
* - immediate start a new transaction
* - continue to drive idle cycles
* - or clock at least 8 idle cycles
*
* Implement last option to favour correctness over
* slight speed decrease
*/
swd_proc.swdptap_seq_out(0, 2);
swd_proc.swdptap_seq_out(0, 8);
}
return response;
}

4
src/target/cortexm.c
View File

@ -535,8 +535,6 @@ void cortexm_detach(target *t)
target_mem_write32(t, CORTEXM_DEMCR, ap->ap_cortexm_demcr);
/* Disable debug */
target_mem_write32(t, CORTEXM_DHCSR, CORTEXM_DHCSR_DBGKEY);
/* Add some clock cycles to get the CPU running again.*/
target_mem_read32(t, 0);
}
enum { DB_DHCSR, DB_DCRSR, DB_DCRDR, DB_DEMCR };
@ -836,8 +834,6 @@ static void cortexm_halt_resume(target *t, bool step)
target_mem_write32(t, CORTEXM_ICIALLU, 0);
target_mem_write32(t, CORTEXM_DHCSR, dhcsr);
/* Add some clock cycles to get the CPU running again.*/
target_mem_read32(t, 0);
}
static int cortexm_fault_unwind(target *t)