diff options
Diffstat (limited to 'util/romcc/tests/simple_test56.c')
| -rw-r--r-- | util/romcc/tests/simple_test56.c | 43 |
1 files changed, 43 insertions, 0 deletions
diff --git a/util/romcc/tests/simple_test56.c b/util/romcc/tests/simple_test56.c new file mode 100644 index 0000000000..831ee9a4ca --- /dev/null +++ b/util/romcc/tests/simple_test56.c @@ -0,0 +1,43 @@ + +static void spd_enable_refresh(void) +{ + /* + * Effects: Uses serial presence detect to set the + * refresh rate in the DRAMC register. + * see spd_set_dramc for the other values. + * FIXME: Check for illegal/unsupported ram configurations and abort + */ + static const unsigned char refresh_rates[] = { + 0x01, /* Normal 15.625 us -> 15.6 us */ + 0x05, /* Reduced(.25X) 3.9 us -> 7.8 us */ + 0x05, /* Reduced(.5X) 7.8 us -> 7.8 us */ + 0x02, /* Extended(2x) 31.3 us -> 31.2 us */ + 0x03, /* Extended(4x) 62.5 us -> 62.4 us */ + 0x04, /* Extended(8x) 125 us -> 124.8 us */ + }; + /* Find the first dimm and assume the rest are the same */ + int byte; + unsigned device; + unsigned refresh_rate; + byte = -1; + device = 0x50; + while ((byte < 0) && (device <= 0x57)) { + byte = __builtin_inl(device); + device += 1; + } + if (byte < 0) { + /* We couldn't find anything we must have no memory */ + while(1); + } + byte &= 0x7f; + /* Default refresh rate be conservative */ + refresh_rate = 5; + /* see if the ram refresh is a supported one */ + if (byte < 6) { + refresh_rate = refresh_rates[byte]; + } + byte = __builtin_inb(0x57); + byte &= 0xf8; + byte |= refresh_rate; + __builtin_outb(byte, 0x57); +} |