+/*
+ * Do 0-length transaction using bit-banging through IIC_DIRECTCNTL register.
+ */
+
+/* Wait for SCL and/or SDA to be high */
+static int iic_dc_wait(volatile struct iic_regs __iomem *iic, u8 mask)
+{
+ unsigned long x = jiffies + HZ / 28 + 2;
+ while ((in_8(&iic->directcntl) & mask) != mask){
+ if (unlikely(time_after(jiffies, x)))
+ return -1;
+ cond_resched();
+ }
+ return 0;
+}
+
+static int iic_smbus_quick(struct ibm_iic_private* dev, const struct i2c_msg* p)
+{
+ volatile struct iic_regs __iomem *iic = dev->vaddr;
+ const struct i2c_timings* t = &timings[dev->fast_mode ? 1 : 0];
+ u8 mask, v, sda;
+ int i, res;
+
+ /* Only 7-bit addresses are supported */
+ if (unlikely(p->flags & I2C_M_TEN)){
+ DBG("%d: smbus_quick - 10 bit addresses are not supported\n",
+ dev->idx);
+ return -EINVAL;
+ }
+
+ DBG("%d: smbus_quick(0x%02x)\n", dev->idx, p->addr);
+
+ /* Reset IIC interface */
+ out_8(&iic->xtcntlss, XTCNTLSS_SRST);
+
+ /* Wait for bus to become free */
+ out_8(&iic->directcntl, DIRCNTL_SDAC | DIRCNTL_SCC);
+ if (unlikely(iic_dc_wait(iic, DIRCNTL_MSDA | DIRCNTL_MSC)))
+ goto err;
+ ndelay(t->buf);
+
+ /* START */
+ out_8(&iic->directcntl, DIRCNTL_SCC);
+ sda = 0;
+ ndelay(t->hd_sta);
+
+ /* Send address */
+ v = (u8)((p->addr << 1) | ((p->flags & I2C_M_RD) ? 1 : 0));
+ for (i = 0, mask = 0x80; i < 8; ++i, mask >>= 1){
+ out_8(&iic->directcntl, sda);
+ ndelay(t->low / 2);
+ sda = (v & mask) ? DIRCNTL_SDAC : 0;
+ out_8(&iic->directcntl, sda);
+ ndelay(t->low / 2);
+
+ out_8(&iic->directcntl, DIRCNTL_SCC | sda);
+ if (unlikely(iic_dc_wait(iic, DIRCNTL_MSC)))
+ goto err;
+ ndelay(t->high);
+ }
+
+ /* ACK */
+ out_8(&iic->directcntl, sda);
+ ndelay(t->low / 2);
+ out_8(&iic->directcntl, DIRCNTL_SDAC);
+ ndelay(t->low / 2);
+ out_8(&iic->directcntl, DIRCNTL_SDAC | DIRCNTL_SCC);
+ if (unlikely(iic_dc_wait(iic, DIRCNTL_MSC)))
+ goto err;
+ res = (in_8(&iic->directcntl) & DIRCNTL_MSDA) ? -EREMOTEIO : 1;
+ ndelay(t->high);
+
+ /* STOP */
+ out_8(&iic->directcntl, 0);
+ ndelay(t->low);
+ out_8(&iic->directcntl, DIRCNTL_SCC);
+ if (unlikely(iic_dc_wait(iic, DIRCNTL_MSC)))
+ goto err;
+ ndelay(t->su_sto);
+ out_8(&iic->directcntl, DIRCNTL_SDAC | DIRCNTL_SCC);
+
+ ndelay(t->buf);
+
+ DBG("%d: smbus_quick -> %s\n", dev->idx, res ? "NACK" : "ACK");
+out:
+ /* Remove reset */
+ out_8(&iic->xtcntlss, 0);
+
+ /* Reinitialize interface */
+ iic_dev_init(dev);
+
+ return res;
+err:
+ DBG("%d: smbus_quick - bus is stuck\n", dev->idx);
+ res = -EREMOTEIO;
+ goto out;
+}
+