diff options
| -rw-r--r-- | core/init.c | 8 | ||||
| -rw-r--r-- | hw/chiptod.c | 15 |
2 files changed, 16 insertions, 7 deletions
diff --git a/core/init.c b/core/init.c index 2eeba75..9eb8e25 100644 --- a/core/init.c +++ b/core/init.c @@ -972,9 +972,11 @@ void __noreturn __nomcount main_cpu_entry(const void *fdt) cpu_set_sreset_enable(true); /* - * Synchronize time bases. Thi resets all the TB values to a small - * value (so they appear to go backward at this point), and synchronize - * all core timebases to the global ChipTOD network + * Synchronize time bases. Prior to chiptod_init() the timebase + * is free-running at a frequency based on the core clock rather + * than being synchronised to the ChipTOD network. This means + * that the timestamps in early boot might be a little off compared + * to wall clock time. */ chiptod_init(); diff --git a/hw/chiptod.c b/hw/chiptod.c index b9e4774..cacc273 100644 --- a/hw/chiptod.c +++ b/hw/chiptod.c @@ -120,9 +120,6 @@ #define LOCAL_CORE_FIR 0x0104000C #define LFIR_SWITCH_COMPLETE PPC_BIT(18) -/* Magic TB value. One step cycle ahead of sync */ -#define INIT_TB 0x000000000001ff0 - /* Number of iterations for the various timeouts */ #define TIMEOUT_LOOPS 20000000 @@ -775,6 +772,7 @@ static void chiptod_reset_tod_errors(void) static void chiptod_sync_master(void *data) { + uint64_t initial_tb_value; bool *result = data; prlog(PR_DEBUG, "Master sync on CPU PIR 0x%04x...\n", @@ -824,8 +822,17 @@ static void chiptod_sync_master(void *data) goto error; } + /* + * Load the master's current timebase value into the Chip TOD + * network. This is so we have sane timestamps across the whole + * IPL process. The Chip TOD documentation says that the loaded + * value needs to be one STEP before a SYNC. In other words, + * set the low bits to 0x1ff0. + */ + initial_tb_value = (mftb() & ~0x1fff) | 0x1ff0; + /* Chip TOD load initial value */ - if (xscom_writeme(TOD_CHIPTOD_LOAD_TB, INIT_TB)) { + if (xscom_writeme(TOD_CHIPTOD_LOAD_TB, initial_tb_value)) { prerror("XSCOM error setting init TB\n"); goto error; } |