| static const char *addr_of_char(unsigned char ch) |
| { |
| static const char byte[] = { |
| 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, |
| 0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f, |
| 0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17, |
| 0x18, 0x19, 0x1a, 0x1b, 0x1c, 0x1d, 0x1e, 0x1f, |
| 0x20, 0x21, 0x22, 0x23, 0x24, 0x25, 0x26, 0x27, |
| 0x28, 0x29, 0x2a, 0x2b, 0x2c, 0x2d, 0x2e, 0x2f, |
| 0x30, 0x31, 0x32, 0x33, 0x34, 0x35, 0x36, 0x37, |
| 0x38, 0x39, 0x3a, 0x3b, 0x3c, 0x3d, 0x3e, 0x3f, |
| 0x40, 0x41, 0x42, 0x43, 0x44, 0x45, 0x46, 0x47, |
| 0x48, 0x49, 0x4a, 0x4b, 0x4c, 0x4d, 0x4e, 0x4f, |
| 0x50, 0x51, 0x52, 0x53, 0x54, 0x55, 0x56, 0x57, |
| 0x58, 0x59, 0x5a, 0x5b, 0x5c, 0x5d, 0x5e, 0x5f, |
| 0x60, 0x61, 0x62, 0x63, 0x64, 0x65, 0x66, 0x67, |
| 0x68, 0x69, 0x6a, 0x6b, 0x6c, 0x6d, 0x6e, 0x6f, |
| 0x70, 0x71, 0x72, 0x73, 0x74, 0x75, 0x76, 0x77, |
| 0x78, 0x79, 0x7a, 0x7b, 0x7c, 0x7d, 0x7e, 0x7f, |
| 0x80, 0x81, 0x82, 0x83, 0x84, 0x85, 0x86, 0x87, |
| 0x88, 0x89, 0x8a, 0x8b, 0x8c, 0x8d, 0x8e, 0x8f, |
| 0x90, 0x91, 0x92, 0x93, 0x94, 0x95, 0x96, 0x97, |
| 0x98, 0x99, 0x9a, 0x9b, 0x9c, 0x9d, 0x9e, 0x9f, |
| 0xa0, 0xa1, 0xa2, 0xa3, 0xa4, 0xa5, 0xa6, 0xa7, |
| 0xa8, 0xa9, 0xaa, 0xab, 0xac, 0xad, 0xae, 0xaf, |
| 0xb0, 0xb1, 0xb2, 0xb3, 0xb4, 0xb5, 0xb6, 0xb7, |
| 0xb8, 0xb9, 0xba, 0xbb, 0xbc, 0xbd, 0xbe, 0xbf, |
| 0xc0, 0xc1, 0xc2, 0xc3, 0xc4, 0xc5, 0xc6, 0xc7, |
| 0xc8, 0xc9, 0xca, 0xcb, 0xcc, 0xcd, 0xce, 0xcf, |
| 0xd0, 0xd1, 0xd2, 0xd3, 0xd4, 0xd5, 0xd6, 0xd7, |
| 0xd8, 0xd9, 0xda, 0xdb, 0xdc, 0xdd, 0xde, 0xdf, |
| 0xe0, 0xe1, 0xe2, 0xe3, 0xe4, 0xe5, 0xe6, 0xe7, |
| 0xe8, 0xe9, 0xea, 0xeb, 0xec, 0xed, 0xee, 0xef, |
| 0xf0, 0xf1, 0xf2, 0xf3, 0xf4, 0xf5, 0xf6, 0xf7, |
| 0xf8, 0xf9, 0xfa, 0xfb, 0xfc, 0xfd, 0xfe, 0xff, |
| }; |
| return byte + ch; |
| } |
| |
| static void console_tx_byte(unsigned char ch) |
| { |
| asm volatile( |
| "int $0x80" |
| : |
| : "a" (4), "b" (1), "c" (addr_of_char(ch)), "d" (1)); |
| } |
| |
| static void console_tx_string(const char *str) |
| { |
| unsigned char ch; |
| while((ch = *str++) != '\0') { |
| console_tx_byte(ch); |
| } |
| } |
| |
| |
| |
| static int smbus_read_byte(unsigned device, unsigned address) |
| { |
| static const unsigned char dimm[] = { |
| 0x80, 0x08, 0x07, 0x0d, 0x0a, 0x02, 0x48, 0x00, 0x04, 0x60, 0x70, 0x02, 0x82, 0x08, 0x08, 0x01, |
| 0x0e, 0x04, 0x0c, 0x01, 0x02, 0x20, 0x00, 0x75, 0x70, 0x00, 0x00, 0x48, 0x30, 0x48, 0x2a, 0x40, |
| 0x80, 0x80, 0x45, 0x45, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, |
| 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x33, |
| 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, |
| 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, |
| 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, |
| 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, |
| 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, |
| 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, |
| 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, |
| 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, |
| 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, |
| 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, |
| 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, |
| 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, |
| |
| 0x80, 0x08, 0x07, 0x0d, 0x0a, 0x02, 0x48, 0x00, 0x04, 0x60, 0x70, 0x02, 0x82, 0x08, 0x08, 0x01, |
| 0x0e, 0x04, 0x0c, 0x01, 0x02, 0x20, 0x00, 0x75, 0x70, 0x00, 0x00, 0x48, 0x30, 0x48, 0x2a, 0x40, |
| 0x80, 0x80, 0x45, 0x45, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, |
| 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x33, |
| 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, |
| 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, |
| 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, |
| 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, |
| 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, |
| 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, |
| 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, |
| 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, |
| 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, |
| 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, |
| 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, |
| 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, |
| }; |
| return dimm[(device << 8) + address]; |
| } |
| |
| #define SMBUS_MEM_DEVICE_START 0x00 |
| #define SMBUS_MEM_DEVICE_END 0x00 |
| #define SMBUS_MEM_DEVICE_INC 1 |
| |
| |
| static void spd_set_memclk(void) |
| { |
| /* Compute the minimum cycle time for these dimms */ |
| unsigned min_cycle_time, min_latency; |
| unsigned device; |
| unsigned value; |
| |
| value = 0x50; |
| min_cycle_time = 0x75; |
| min_latency = 2; |
| device = 0; |
| |
| /* Compute the least latency with the fastest clock supported |
| * by both the memory controller and the dimms. |
| */ |
| for(device = SMBUS_MEM_DEVICE_START; |
| device <= SMBUS_MEM_DEVICE_END; |
| device += SMBUS_MEM_DEVICE_INC) |
| { |
| int new_cycle_time, new_latency; |
| int index; |
| int latencies; |
| int latency; |
| |
| /* First find the supported CAS latencies |
| * Byte 18 for DDR SDRAM is interpreted: |
| * bit 0 == CAS Latency = 1.0 |
| * bit 1 == CAS Latency = 1.5 |
| * bit 2 == CAS Latency = 2.0 |
| * bit 3 == CAS Latency = 2.5 |
| * bit 4 == CAS Latency = 3.0 |
| * bit 5 == CAS Latency = 3.5 |
| * bit 6 == TBD |
| * bit 7 == TBD |
| */ |
| new_cycle_time = 0xa0; |
| new_latency = 5; |
| |
| latencies = smbus_read_byte(device, 18); |
| |
| /* Compute the lowest cas latency supported */ |
| latency = __builtin_bsr(latencies) -2; |
| |
| /* Loop through and find a fast clock with a low latency */ |
| for(index = 0; index < 3; index++, latency++) { |
| int value; |
| if ((latency < 2) || (latency > 4) || |
| (!(latencies & (1 << latency)))) { |
| continue; |
| } |
| value = smbus_read_byte(device, index); |
| if (value < 0) continue; |
| |
| /* Only increase the latency if we decreas the clock */ |
| if ((value >= min_cycle_time) && (value < new_cycle_time)) { |
| new_cycle_time = value; |
| new_latency = latency; |
| console_tx_byte(device); |
| |
| } |
| } |
| console_tx_string("Transmitting this string causes problems\n"); |
| /* Does min_latency need to be increased? */ |
| if (new_cycle_time > min_cycle_time) { |
| min_cycle_time = new_cycle_time; |
| } |
| /* Does min_cycle_time need to be increased? */ |
| if (new_latency > min_latency) { |
| min_latency = new_latency; |
| } |
| } |
| } |