drivers/gpu/drm/nouveau/core/subdev/bios/i2c.c

/*
 * Copyright 2012 Red Hat Inc.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
 * THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR ANY CLAIM, DAMAGES OR
 * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
 * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
 * OTHER DEALINGS IN THE SOFTWARE.
 *
 * Authors: Ben Skeggs
 */


#include "subdev/bios.h"
#include "subdev/bios/dcb.h"
#include "subdev/bios/i2c.h"

u16
dcb_i2c_table(struct nouveau_bios *bios, u8 *ver, u8 *hdr, u8 *cnt, u8 *len)
{
	u16 i2c = 0x0000;
	u16 dcb = dcb_table(bios, ver, hdr, cnt, len);
	if (dcb) {
		if (*ver >= 0x15)
			i2c = nv_ro16(bios, dcb + 2);
		if (*ver >= 0x30)
			i2c = nv_ro16(bios, dcb + 4);
	}

	if (i2c && *ver >= 0x30) {
		*ver = nv_ro08(bios, i2c + 0);
		*hdr = nv_ro08(bios, i2c + 1);
		*cnt = nv_ro08(bios, i2c + 2);
		*len = nv_ro08(bios, i2c + 3);
	} else {
		*ver = *ver; /* use DCB version */
		*hdr = 0;
		*cnt = 16;
		*len = 4;
	}

	return i2c;
}

u16
dcb_i2c_entry(struct nouveau_bios *bios, u8 idx, u8 *ver, u8 *len)
{
	u8  hdr, cnt;
	u16 i2c = dcb_i2c_table(bios, ver, &hdr, &cnt, len);
	if (i2c && idx < cnt)
		return i2c + hdr + (idx * *len);
	return 0x0000;
}

int
dcb_i2c_parse(struct nouveau_bios *bios, u8 idx, struct dcb_i2c_entry *info)
{
	u8  ver, len;
	u16 ent = dcb_i2c_entry(bios, idx, &ver, &len);
	if (ent) {
		info->type  = nv_ro08(bios, ent + 3);
		info->share = DCB_I2C_UNUSED;
		if (ver < 0x30) {
			info->type &= 0x07;
			if (info->type == 0x07)
				info->type = DCB_I2C_UNUSED;
		}

		switch (info->type) {
		case DCB_I2C_NV04_BIT:
			info->drive = nv_ro08(bios, ent + 0);
			info->sense = nv_ro08(bios, ent + 1);
			return 0;
		case DCB_I2C_NV4E_BIT:
			info->drive = nv_ro08(bios, ent + 1);
			return 0;
		case DCB_I2C_NVIO_BIT:
		case DCB_I2C_NVIO_AUX:
			info->drive = nv_ro08(bios, ent + 0) & 0x0f;
			if (nv_ro08(bios, ent + 1) & 0x01) {
				info->share  = nv_ro08(bios, ent + 1) >> 1;
				info->share &= 0x0f;
			}
			return 0;
		case DCB_I2C_UNUSED:
			return 0;
		default:
			nv_warn(bios, "unknown i2c type %d\n", info->type);
			info->type = DCB_I2C_UNUSED;
			return 0;
		}
	}

	if (bios->bmp_offset && idx < 2) {
		/* BMP (from v4.0 has i2c info in the structure, it's in a
		 * fixed location on earlier VBIOS
		 */
		if (nv_ro08(bios, bios->bmp_offset + 5) < 4)
			ent = 0x0048;
		else
			ent = 0x0036 + bios->bmp_offset;

		if (idx == 0) {
			info->drive = nv_ro08(bios, ent + 4);
			if (!info->drive) info->drive = 0x3f;
			info->sense = nv_ro08(bios, ent + 5);
			if (!info->sense) info->sense = 0x3e;
		} else
		if (idx == 1) {
			info->drive = nv_ro08(bios, ent + 6);
			if (!info->drive) info->drive = 0x37;
			info->sense = nv_ro08(bios, ent + 7);
			if (!info->sense) info->sense = 0x36;
		}

		info->type  = DCB_I2C_NV04_BIT;
		info->share = DCB_I2C_UNUSED;
		return 0;
	}

	return -ENOENT;
}