REG_IPD
i2c_writel(i2c, REG_INT_ALL, REG_IPD);
i2c_writel(i2c, REG_INT_START, REG_IPD);
i2c_writel(i2c, REG_INT_MBTF, REG_IPD);
i2c_writel(i2c, REG_INT_MBRF | REG_INT_START, REG_IPD);
i2c_writel(i2c, REG_INT_STOP, REG_IPD);
ipd = i2c_readl(i2c, REG_IPD);
i2c_writel(i2c, REG_INT_NAKRCV, REG_IPD);