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path: root/drivers/spi/spi-pxa2xx-dma.c
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Diffstat (limited to 'drivers/spi/spi-pxa2xx-dma.c')
-rw-r--r--drivers/spi/spi-pxa2xx-dma.c392
1 files changed, 392 insertions, 0 deletions
diff --git a/drivers/spi/spi-pxa2xx-dma.c b/drivers/spi/spi-pxa2xx-dma.c
new file mode 100644
index 0000000..c735c5a
--- /dev/null
+++ b/drivers/spi/spi-pxa2xx-dma.c
@@ -0,0 +1,392 @@
+/*
+ * PXA2xx SPI DMA engine support.
+ *
+ * Copyright (C) 2013, Intel Corporation
+ * Author: Mika Westerberg <mika.westerberg@linux.intel.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <linux/init.h>
+#include <linux/device.h>
+#include <linux/dma-mapping.h>
+#include <linux/dmaengine.h>
+#include <linux/pxa2xx_ssp.h>
+#include <linux/scatterlist.h>
+#include <linux/sizes.h>
+#include <linux/spi/spi.h>
+#include <linux/spi/pxa2xx_spi.h>
+
+#include "spi-pxa2xx.h"
+
+static int pxa2xx_spi_map_dma_buffer(struct driver_data *drv_data,
+ enum dma_data_direction dir)
+{
+ int i, nents, len = drv_data->len;
+ struct scatterlist *sg;
+ struct device *dmadev;
+ struct sg_table *sgt;
+ void *buf, *pbuf;
+
+ /*
+ * Some DMA controllers have problems transferring buffers that are
+ * not multiple of 4 bytes. So we truncate the transfer so that it
+ * is suitable for such controllers, and handle the trailing bytes
+ * manually after the DMA completes.
+ *
+ * REVISIT: It would be better if this information could be
+ * retrieved directly from the DMA device in a similar way than
+ * ->copy_align etc. is done.
+ */
+ len = ALIGN(drv_data->len, 4);
+
+ if (dir == DMA_TO_DEVICE) {
+ dmadev = drv_data->tx_chan->device->dev;
+ sgt = &drv_data->tx_sgt;
+ buf = drv_data->tx;
+ drv_data->tx_map_len = len;
+ } else {
+ dmadev = drv_data->rx_chan->device->dev;
+ sgt = &drv_data->rx_sgt;
+ buf = drv_data->rx;
+ drv_data->rx_map_len = len;
+ }
+
+ nents = DIV_ROUND_UP(len, SZ_2K);
+ if (nents != sgt->nents) {
+ int ret;
+
+ sg_free_table(sgt);
+ ret = sg_alloc_table(sgt, nents, GFP_KERNEL);
+ if (ret)
+ return ret;
+ }
+
+ pbuf = buf;
+ for_each_sg(sgt->sgl, sg, sgt->nents, i) {
+ size_t bytes = min_t(size_t, len, SZ_2K);
+
+ if (buf)
+ sg_set_buf(sg, pbuf, bytes);
+ else
+ sg_set_buf(sg, drv_data->dummy, bytes);
+
+ pbuf += bytes;
+ len -= bytes;
+ }
+
+ nents = dma_map_sg(dmadev, sgt->sgl, sgt->nents, dir);
+ if (!nents)
+ return -ENOMEM;
+
+ return nents;
+}
+
+static void pxa2xx_spi_unmap_dma_buffer(struct driver_data *drv_data,
+ enum dma_data_direction dir)
+{
+ struct device *dmadev;
+ struct sg_table *sgt;
+
+ if (dir == DMA_TO_DEVICE) {
+ dmadev = drv_data->tx_chan->device->dev;
+ sgt = &drv_data->tx_sgt;
+ } else {
+ dmadev = drv_data->rx_chan->device->dev;
+ sgt = &drv_data->rx_sgt;
+ }
+
+ dma_unmap_sg(dmadev, sgt->sgl, sgt->nents, dir);
+}
+
+static void pxa2xx_spi_unmap_dma_buffers(struct driver_data *drv_data)
+{
+ if (!drv_data->dma_mapped)
+ return;
+
+ pxa2xx_spi_unmap_dma_buffer(drv_data, DMA_FROM_DEVICE);
+ pxa2xx_spi_unmap_dma_buffer(drv_data, DMA_TO_DEVICE);
+
+ drv_data->dma_mapped = 0;
+}
+
+static void pxa2xx_spi_dma_transfer_complete(struct driver_data *drv_data,
+ bool error)
+{
+ struct spi_message *msg = drv_data->cur_msg;
+
+ /*
+ * It is possible that one CPU is handling ROR interrupt and other
+ * just gets DMA completion. Calling pump_transfers() twice for the
+ * same transfer leads to problems thus we prevent concurrent calls
+ * by using ->dma_running.
+ */
+ if (atomic_dec_and_test(&drv_data->dma_running)) {
+ void __iomem *reg = drv_data->ioaddr;
+
+ /*
+ * If the other CPU is still handling the ROR interrupt we
+ * might not know about the error yet. So we re-check the
+ * ROR bit here before we clear the status register.
+ */
+ if (!error) {
+ u32 status = read_SSSR(reg) & drv_data->mask_sr;
+ error = status & SSSR_ROR;
+ }
+
+ /* Clear status & disable interrupts */
+ write_SSCR1(read_SSCR1(reg) & ~drv_data->dma_cr1, reg);
+ write_SSSR_CS(drv_data, drv_data->clear_sr);
+ if (!pxa25x_ssp_comp(drv_data))
+ write_SSTO(0, reg);
+
+ if (!error) {
+ pxa2xx_spi_unmap_dma_buffers(drv_data);
+
+ /* Handle the last bytes of unaligned transfer */
+ drv_data->tx += drv_data->tx_map_len;
+ drv_data->write(drv_data);
+
+ drv_data->rx += drv_data->rx_map_len;
+ drv_data->read(drv_data);
+
+ msg->actual_length += drv_data->len;
+ msg->state = pxa2xx_spi_next_transfer(drv_data);
+ } else {
+ /* In case we got an error we disable the SSP now */
+ write_SSCR0(read_SSCR0(reg) & ~SSCR0_SSE, reg);
+
+ msg->state = ERROR_STATE;
+ }
+
+ tasklet_schedule(&drv_data->pump_transfers);
+ }
+}
+
+static void pxa2xx_spi_dma_callback(void *data)
+{
+ pxa2xx_spi_dma_transfer_complete(data, false);
+}
+
+static struct dma_async_tx_descriptor *
+pxa2xx_spi_dma_prepare_one(struct driver_data *drv_data,
+ enum dma_transfer_direction dir)
+{
+ struct pxa2xx_spi_master *pdata = drv_data->master_info;
+ struct chip_data *chip = drv_data->cur_chip;
+ enum dma_slave_buswidth width;
+ struct dma_slave_config cfg;
+ struct dma_chan *chan;
+ struct sg_table *sgt;
+ int nents, ret;
+
+ switch (drv_data->n_bytes) {
+ case 1:
+ width = DMA_SLAVE_BUSWIDTH_1_BYTE;
+ break;
+ case 2:
+ width = DMA_SLAVE_BUSWIDTH_2_BYTES;
+ break;
+ default:
+ width = DMA_SLAVE_BUSWIDTH_4_BYTES;
+ break;
+ }
+
+ memset(&cfg, 0, sizeof(cfg));
+ cfg.direction = dir;
+
+ if (dir == DMA_MEM_TO_DEV) {
+ cfg.dst_addr = drv_data->ssdr_physical;
+ cfg.dst_addr_width = width;
+ cfg.dst_maxburst = chip->dma_burst_size;
+ cfg.slave_id = pdata->tx_slave_id;
+
+ sgt = &drv_data->tx_sgt;
+ nents = drv_data->tx_nents;
+ chan = drv_data->tx_chan;
+ } else {
+ cfg.src_addr = drv_data->ssdr_physical;
+ cfg.src_addr_width = width;
+ cfg.src_maxburst = chip->dma_burst_size;
+ cfg.slave_id = pdata->rx_slave_id;
+
+ sgt = &drv_data->rx_sgt;
+ nents = drv_data->rx_nents;
+ chan = drv_data->rx_chan;
+ }
+
+ ret = dmaengine_slave_config(chan, &cfg);
+ if (ret) {
+ dev_warn(&drv_data->pdev->dev, "DMA slave config failed\n");
+ return NULL;
+ }
+
+ return dmaengine_prep_slave_sg(chan, sgt->sgl, nents, dir,
+ DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
+}
+
+static bool pxa2xx_spi_dma_filter(struct dma_chan *chan, void *param)
+{
+ const struct pxa2xx_spi_master *pdata = param;
+
+ return chan->chan_id == pdata->tx_chan_id ||
+ chan->chan_id == pdata->rx_chan_id;
+}
+
+bool pxa2xx_spi_dma_is_possible(size_t len)
+{
+ return len <= MAX_DMA_LEN;
+}
+
+int pxa2xx_spi_map_dma_buffers(struct driver_data *drv_data)
+{
+ const struct chip_data *chip = drv_data->cur_chip;
+ int ret;
+
+ if (!chip->enable_dma)
+ return 0;
+
+ /* Don't bother with DMA if we can't do even a single burst */
+ if (drv_data->len < chip->dma_burst_size)
+ return 0;
+
+ ret = pxa2xx_spi_map_dma_buffer(drv_data, DMA_TO_DEVICE);
+ if (ret <= 0) {
+ dev_warn(&drv_data->pdev->dev, "failed to DMA map TX\n");
+ return 0;
+ }
+
+ drv_data->tx_nents = ret;
+
+ ret = pxa2xx_spi_map_dma_buffer(drv_data, DMA_FROM_DEVICE);
+ if (ret <= 0) {
+ pxa2xx_spi_unmap_dma_buffer(drv_data, DMA_TO_DEVICE);
+ dev_warn(&drv_data->pdev->dev, "failed to DMA map RX\n");
+ return 0;
+ }
+
+ drv_data->rx_nents = ret;
+ return 1;
+}
+
+irqreturn_t pxa2xx_spi_dma_transfer(struct driver_data *drv_data)
+{
+ u32 status;
+
+ status = read_SSSR(drv_data->ioaddr) & drv_data->mask_sr;
+ if (status & SSSR_ROR) {
+ dev_err(&drv_data->pdev->dev, "FIFO overrun\n");
+
+ dmaengine_terminate_all(drv_data->rx_chan);
+ dmaengine_terminate_all(drv_data->tx_chan);
+
+ pxa2xx_spi_dma_transfer_complete(drv_data, true);
+ return IRQ_HANDLED;
+ }
+
+ return IRQ_NONE;
+}
+
+int pxa2xx_spi_dma_prepare(struct driver_data *drv_data, u32 dma_burst)
+{
+ struct dma_async_tx_descriptor *tx_desc, *rx_desc;
+
+ tx_desc = pxa2xx_spi_dma_prepare_one(drv_data, DMA_MEM_TO_DEV);
+ if (!tx_desc) {
+ dev_err(&drv_data->pdev->dev,
+ "failed to get DMA TX descriptor\n");
+ return -EBUSY;
+ }
+
+ rx_desc = pxa2xx_spi_dma_prepare_one(drv_data, DMA_DEV_TO_MEM);
+ if (!rx_desc) {
+ dev_err(&drv_data->pdev->dev,
+ "failed to get DMA RX descriptor\n");
+ return -EBUSY;
+ }
+
+ /* We are ready when RX completes */
+ rx_desc->callback = pxa2xx_spi_dma_callback;
+ rx_desc->callback_param = drv_data;
+
+ dmaengine_submit(rx_desc);
+ dmaengine_submit(tx_desc);
+ return 0;
+}
+
+void pxa2xx_spi_dma_start(struct driver_data *drv_data)
+{
+ dma_async_issue_pending(drv_data->rx_chan);
+ dma_async_issue_pending(drv_data->tx_chan);
+
+ atomic_set(&drv_data->dma_running, 1);
+}
+
+int pxa2xx_spi_dma_setup(struct driver_data *drv_data)
+{
+ struct pxa2xx_spi_master *pdata = drv_data->master_info;
+ dma_cap_mask_t mask;
+
+ dma_cap_zero(mask);
+ dma_cap_set(DMA_SLAVE, mask);
+
+ drv_data->dummy = devm_kzalloc(&drv_data->pdev->dev, SZ_2K, GFP_KERNEL);
+ if (!drv_data->dummy)
+ return -ENOMEM;
+
+ drv_data->tx_chan = dma_request_channel(mask, pxa2xx_spi_dma_filter,
+ pdata);
+ if (!drv_data->tx_chan)
+ return -ENODEV;
+
+ drv_data->rx_chan = dma_request_channel(mask, pxa2xx_spi_dma_filter,
+ pdata);
+ if (!drv_data->rx_chan) {
+ dma_release_channel(drv_data->tx_chan);
+ drv_data->tx_chan = NULL;
+ return -ENODEV;
+ }
+
+ return 0;
+}
+
+void pxa2xx_spi_dma_release(struct driver_data *drv_data)
+{
+ if (drv_data->rx_chan) {
+ dmaengine_terminate_all(drv_data->rx_chan);
+ dma_release_channel(drv_data->rx_chan);
+ sg_free_table(&drv_data->rx_sgt);
+ drv_data->rx_chan = NULL;
+ }
+ if (drv_data->tx_chan) {
+ dmaengine_terminate_all(drv_data->tx_chan);
+ dma_release_channel(drv_data->tx_chan);
+ sg_free_table(&drv_data->tx_sgt);
+ drv_data->tx_chan = NULL;
+ }
+}
+
+void pxa2xx_spi_dma_resume(struct driver_data *drv_data)
+{
+}
+
+int pxa2xx_spi_set_dma_burst_and_threshold(struct chip_data *chip,
+ struct spi_device *spi,
+ u8 bits_per_word, u32 *burst_code,
+ u32 *threshold)
+{
+ struct pxa2xx_spi_chip *chip_info = spi->controller_data;
+
+ /*
+ * If the DMA burst size is given in chip_info we use that,
+ * otherwise we use the default. Also we use the default FIFO
+ * thresholds for now.
+ */
+ *burst_code = chip_info ? chip_info->dma_burst_size : 16;
+ *threshold = SSCR1_RxTresh(RX_THRESH_DFLT)
+ | SSCR1_TxTresh(TX_THRESH_DFLT);
+
+ return 0;
+}