1 #include <cpu/amd/gx2def.h>
3 static void sdram_set_registers(const struct mem_controller *ctrl)
8 /* Section 6.1.3, LX processor databooks, BIOS Initialization Sequence
9 * Section 4.1.4, GX/CS5535 GeodeROM Porting guide */
10 static void sdram_enable(int controllers, const struct mem_controller *ctrl)
15 /* 2. clock gating for PMode */
16 msr = rdmsr(0x20002004);
19 wrmsr(0x20002004, msr);
20 /* undocmented bits in GX, in LX there are
21 * 8 bits in PM1_UP_DLY */
22 msr = rdmsr(0x2000001a);
24 wrmsr(0x2000001a, msr);
25 //print_debug("sdram_enable step 2\r\n");
27 /* 3. release CKE mask to enable CKE */
28 msr = rdmsr(0x2000001d);
29 msr.lo &= ~(0x03 << 8);
30 wrmsr(0x2000201d, msr);
31 //print_debug("sdram_enable step 3\r\n");
33 /* 4. set and clear REF_TST 16 times, more shouldn't hurt
34 * why this is before EMRS and MRS ? */
35 for (i = 0; i < 19; i++) {
36 msr = rdmsr(0x20000018);
37 msr.lo |= (0x01 << 3);
38 wrmsr(0x20000018, msr);
39 msr.lo &= ~(0x01 << 3);
40 wrmsr(0x20000018, msr);
42 //print_debug("sdram_enable step 4\r\n");
44 /* 5. set refresh interval */
45 msr = rdmsr(0x20000018);
46 msr.lo &= ~(0xffff << 8);
47 msr.lo |= (0x34 << 8);
48 wrmsr(0x20000018, msr);
49 /* set refresh staggering to 4 SDRAM clocks */
50 msr = rdmsr(0x20000018);
51 msr.lo &= ~(0x03 << 6);
52 msr.lo |= (0x00 << 6);
53 wrmsr(0x20000018, msr);
54 //print_debug("sdram_enable step 5\r\n");
56 /* 6. enable DLL, load Extended Mode Register by set and clear PROG_DRAM */
57 msr = rdmsr(0x20000018);
58 msr.lo |= ((0x01 << 28) | 0x01);
59 wrmsr(0x20000018, msr);
60 msr.lo &= ~((0x01 << 28) | 0x01);
61 wrmsr(0x20000018, msr);
62 //print_debug("sdram_enable step 6\r\n");
64 /* 7. Reset DLL, Bit 27 is undocumented in GX datasheet,
65 * it is documented in LX datasheet */
66 /* load Mode Register by set and clear PROG_DRAM */
67 msr = rdmsr(0x20000018);
68 msr.lo |= ((0x01 << 27) | 0x01);
69 wrmsr(0x20000018, msr);
70 msr.lo &= ~((0x01 << 27) | 0x01);
71 wrmsr(0x20000018, msr);
72 //print_debug("sdram_enable step 7\r\n");
74 /* 8. load Mode Register by set and clear PROG_DRAM */
75 msr = rdmsr(0x20000018);
77 wrmsr(0x20000018, msr);
79 wrmsr(0x20000018, msr);
80 //print_debug("sdram_enable step 8\r\n");
83 for (i = 0; i < 200; i++)
87 msr = rdmsr(0x2000001f);
90 wrmsr(0x2000001f, msr);
92 /* set delay control */
93 msr = rdmsr(0x4c00000f);
96 wrmsr(0x4c00000f, msr);
98 /* DRAM working now?? */