diff options
Diffstat (limited to 'drivers/spi/spi-pxa2xx-dma.c')
| -rw-r--r-- | drivers/spi/spi-pxa2xx-dma.c | 392 |
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 000000000000..c735c5a008a2 --- /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; +} |