I came up with this for the 74 cycle delay:
                samcop_write_register(samcop, SAMCOP_SDIPRE, sdi_psc);
                /* wait for the prescribed time that the card requires to init */
                if ((clock_rate / sdi_psc) > 1000000UL)
                        ndelay(sdi_psc * 1000000000UL / clock_rate * SAMCOP_CARD_INIT_CYCLES);
                else
                        udelay(sdi_psc * 1000000UL / clock_rate * SAMCOP_CARD_INIT_CYCLES);