+static bool filter(struct dma_chan *chan, void *slave)
+{
+ struct at_dma_slave *sl = slave;
+
+ if (sl->dma_dev == chan->device->dev) {
+ chan->private = sl;
+ return true;
+ } else {
+ return false;
+ }
+}
+
+static int at91_twi_configure_dma(struct at91_twi_dev *dev, u32 phy_addr)
+{
+ int ret = 0;
+ struct at_dma_slave *sdata;
+ struct dma_slave_config slave_config;
+ struct at91_twi_dma *dma = &dev->dma;
+
+ sdata = &dev->pdata->dma_slave;
+
+ memset(&slave_config, 0, sizeof(slave_config));
+ slave_config.src_addr = (dma_addr_t)phy_addr + AT91_TWI_RHR;
+ slave_config.src_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE;
+ slave_config.src_maxburst = 1;
+ slave_config.dst_addr = (dma_addr_t)phy_addr + AT91_TWI_THR;
+ slave_config.dst_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE;
+ slave_config.dst_maxburst = 1;
+ slave_config.device_fc = false;
+
+ if (sdata && sdata->dma_dev) {
+ dma_cap_mask_t mask;
+
+ dma_cap_zero(mask);
+ dma_cap_set(DMA_SLAVE, mask);
+ dma->chan_tx = dma_request_channel(mask, filter, sdata);
+ if (!dma->chan_tx) {
+ dev_err(dev->dev, "no DMA channel available for tx\n");
+ ret = -EBUSY;
+ goto error;
+ }
+ dma->chan_rx = dma_request_channel(mask, filter, sdata);
+ if (!dma->chan_rx) {
+ dev_err(dev->dev, "no DMA channel available for rx\n");
+ ret = -EBUSY;
+ goto error;
+ }
+ } else {
+ ret = -EINVAL;
+ goto error;
+ }
+
+ slave_config.direction = DMA_MEM_TO_DEV;
+ if (dmaengine_slave_config(dma->chan_tx, &slave_config)) {
+ dev_err(dev->dev, "failed to configure tx channel\n");
+ ret = -EINVAL;
+ goto error;
+ }
+
+ slave_config.direction = DMA_DEV_TO_MEM;
+ if (dmaengine_slave_config(dma->chan_rx, &slave_config)) {
+ dev_err(dev->dev, "failed to configure rx channel\n");
+ ret = -EINVAL;
+ goto error;
+ }
+
+ sg_init_table(&dma->sg, 1);
+ dma->buf_mapped = false;
+ dma->xfer_in_progress = false;
+
+ dev_info(dev->dev, "using %s (tx) and %s (rx) for DMA transfers\n",
+ dma_chan_name(dma->chan_tx), dma_chan_name(dma->chan_rx));
+
+ return ret;
+
+error:
+ dev_info(dev->dev, "can't use DMA\n");
+ if (dma->chan_rx)
+ dma_release_channel(dma->chan_rx);
+ if (dma->chan_tx)
+ dma_release_channel(dma->chan_tx);
+ return ret;
+}
+
+static struct at91_twi_pdata *at91_twi_get_driver_data(