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| author | David Brownell <dbrownell@users.sourceforge.net> | 2010-01-05 12:55:46 -0800 |
|---|---|---|
| committer | David Brownell <dbrownell@users.sourceforge.net> | 2010-01-05 12:55:46 -0800 |
| commit | adf2a9a267422a2914a50b4a4a35a0e19b25d1c3 (patch) | |
| tree | ec449858330eef5e9185264abde215cf5c598c00 /src | |
| parent | 9d83df72dcbfc791b470b12949890df3f2d1508d (diff) | |
| download | openocd_libswd-adf2a9a267422a2914a50b4a4a35a0e19b25d1c3.tar.gz openocd_libswd-adf2a9a267422a2914a50b4a4a35a0e19b25d1c3.tar.bz2 openocd_libswd-adf2a9a267422a2914a50b4a4a35a0e19b25d1c3.tar.xz openocd_libswd-adf2a9a267422a2914a50b4a4a35a0e19b25d1c3.zip | |
ARM: add comments re DAP assumptions
I think some of these assumptions are not well-founded.
Related, that swjdp_transaction_endcheck() is a bit iffy.
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Diffstat (limited to 'src')
| -rw-r--r-- | src/target/arm_adi_v5.c | 16 |
1 files changed, 14 insertions, 2 deletions
diff --git a/src/target/arm_adi_v5.c b/src/target/arm_adi_v5.c index 82a2a28a..9f260642 100644 --- a/src/target/arm_adi_v5.c +++ b/src/target/arm_adi_v5.c @@ -195,8 +195,12 @@ static int scan_inout_check_u32(struct swjdp_common *swjdp, uint8_t instr, uint8_t reg_addr, uint8_t RnW, uint32_t outvalue, uint32_t *invalue) { + /* Issue the read or write */ adi_jtag_dp_scan_u32(swjdp, instr, reg_addr, RnW, outvalue, NULL, NULL); + /* For reads, collect posted value; RDBUFF has no other effect. + * Assumes read gets acked with OK/FAULT, and CTRL_STAT says "OK". + */ if ((RnW == DPAP_READ) && (invalue != NULL)) adi_jtag_dp_scan_u32(swjdp, JTAG_DP_DPACC, DP_RDBUFF, DPAP_READ, 0, invalue, &swjdp->ack); @@ -235,6 +239,9 @@ int swjdp_transaction_endcheck(struct swjdp_common *swjdp) /* Why??? second time it works??? */ #endif + /* Post CTRL/STAT read; discard any previous posted read value + * but collect its ACK status. + */ scan_inout_check_u32(swjdp, JTAG_DP_DPACC, DP_CTRL_STAT, DPAP_READ, 0, &ctrlstat); if ((retval = jtag_execute_queue()) != ERROR_OK) @@ -787,13 +794,18 @@ int mem_ap_read_buf_u32(struct swjdp_common *swjdp, uint8_t *buffer, int count, DPAP_READ, 0, NULL, NULL); for (readcount = 0; readcount < blocksize - 1; readcount++) { - /* Scan out read instruction and scan in previous value */ + /* Scan out next read; scan in posted value for the + * previous one. Assumes read is acked "OK/FAULT", + * and CTRL_STAT says that meant "OK". + */ adi_jtag_dp_scan(swjdp, JTAG_DP_APACC, AP_REG_DRW, DPAP_READ, 0, buffer + 4 * readcount, &swjdp->ack); } - /* Scan in last value */ + /* Scan in last posted value; RDBUFF has no other effect, + * assuming ack is OK/FAULT and CTRL_STAT says "OK". + */ adi_jtag_dp_scan(swjdp, JTAG_DP_DPACC, DP_RDBUFF, DPAP_READ, 0, buffer + 4 * readcount, &swjdp->ack); |