drivers/gpu/drm/nouveau/nvkm/subdev/fb/sddr3.c

Source file repositories/reference/linux-study-clean/drivers/gpu/drm/nouveau/nvkm/subdev/fb/sddr3.c

File Facts

System
Linux kernel
Corpus path
drivers/gpu/drm/nouveau/nvkm/subdev/fb/sddr3.c
Extension
.c
Size
3397 bytes
Lines
121
Domain
Driver Families
Bucket
drivers/gpu
Inferred role
Driver Families: implementation source
Status
source implementation candidate

Why This File Exists

Repeatable hardware-adapter layer. Deep compatibility for every driver is out of scope; this atlas records patterns, probe lifecycles, bus glue, IRQ/DMA usage, and links back to core abstractions.

Dependency Surface

Detected Declarations

Annotated Snippet

struct ramxlat {
	int id;
	u8 enc;
};

static inline int
ramxlat(const struct ramxlat *xlat, int id)
{
	while (xlat->id >= 0) {
		if (xlat->id == id)
			return xlat->enc;
		xlat++;
	}
	return -EINVAL;
}

static const struct ramxlat
ramddr3_cl[] = {
	{ 5, 2 }, { 6, 4 }, { 7, 6 }, { 8, 8 }, { 9, 10 }, { 10, 12 },
	{ 11, 14 },
	/* the below are mentioned in some, but not all, ddr3 docs */
	{ 12, 1 }, { 13, 3 }, { 14, 5 },
	{ -1 }
};

static const struct ramxlat
ramddr3_wr[] = {
	{ 5, 1 }, { 6, 2 }, { 7, 3 }, { 8, 4 }, { 10, 5 }, { 12, 6 },
	/* the below are mentioned in some, but not all, ddr3 docs */
	{ 14, 7 }, { 15, 7 }, { 16, 0 },
	{ -1 }
};

static const struct ramxlat
ramddr3_cwl[] = {
	{ 5, 0 }, { 6, 1 }, { 7, 2 }, { 8, 3 },
	/* the below are mentioned in some, but not all, ddr3 docs */
	{ 9, 4 }, { 10, 5 },
	{ -1 }
};

int
nvkm_sddr3_calc(struct nvkm_ram *ram)
{
	int CWL, CL, WR, DLL = 0, ODT = 0;

	DLL = !ram->next->bios.ramcfg_DLLoff;

	switch (ram->next->bios.timing_ver) {
	case 0x10:
		if (ram->next->bios.timing_hdr < 0x17) {
			/* XXX: NV50: Get CWL from the timing register */
			return -ENOSYS;
		}
		CWL = ram->next->bios.timing_10_CWL;
		CL  = ram->next->bios.timing_10_CL;
		WR  = ram->next->bios.timing_10_WR;
		ODT = ram->next->bios.timing_10_ODT;
		break;
	case 0x20:
		CWL = (ram->next->bios.timing[1] & 0x00000f80) >> 7;
		CL  = (ram->next->bios.timing[1] & 0x0000001f) >> 0;
		WR  = (ram->next->bios.timing[2] & 0x007f0000) >> 16;
		/* XXX: Get these values from the VBIOS instead */
		ODT =   (ram->mr[1] & 0x004) >> 2 |
			(ram->mr[1] & 0x040) >> 5 |
		        (ram->mr[1] & 0x200) >> 7;
		break;
	default:
		return -ENOSYS;
	}

	CWL = ramxlat(ramddr3_cwl, CWL);
	CL  = ramxlat(ramddr3_cl, CL);
	WR  = ramxlat(ramddr3_wr, WR);
	if (CL < 0 || CWL < 0 || WR < 0)
		return -EINVAL;

	ram->mr[0] &= ~0xf74;
	ram->mr[0] |= (WR & 0x07) << 9;
	ram->mr[0] |= (CL & 0x0e) << 3;
	ram->mr[0] |= (CL & 0x01) << 2;

	ram->mr[1] &= ~0x245;
	ram->mr[1] |= (ODT & 0x1) << 2;
	ram->mr[1] |= (ODT & 0x2) << 5;
	ram->mr[1] |= (ODT & 0x4) << 7;
	ram->mr[1] |= !DLL;

	ram->mr[2] &= ~0x038;

Annotation

Implementation Notes