diff options
Diffstat (limited to 'drivers/spi/ep93xx_spi.c')
| -rw-r--r-- | drivers/spi/ep93xx_spi.c | 303 |
1 files changed, 291 insertions, 12 deletions
diff --git a/drivers/spi/ep93xx_spi.c b/drivers/spi/ep93xx_spi.c index d3570071e98f..1cf645479bfe 100644 --- a/drivers/spi/ep93xx_spi.c +++ b/drivers/spi/ep93xx_spi.c @@ -1,7 +1,7 @@ /* * Driver for Cirrus Logic EP93xx SPI controller. * - * Copyright (c) 2010 Mika Westerberg + * Copyright (C) 2010-2011 Mika Westerberg * * Explicit FIFO handling code was inspired by amba-pl022 driver. * @@ -21,13 +21,16 @@ #include <linux/err.h> #include <linux/delay.h> #include <linux/device.h> +#include <linux/dmaengine.h> #include <linux/bitops.h> #include <linux/interrupt.h> #include <linux/platform_device.h> #include <linux/workqueue.h> #include <linux/sched.h> +#include <linux/scatterlist.h> #include <linux/spi/spi.h> +#include <mach/dma.h> #include <mach/ep93xx_spi.h> #define SSPCR0 0x0000 @@ -71,6 +74,7 @@ * @pdev: pointer to platform device * @clk: clock for the controller * @regs_base: pointer to ioremap()'d registers + * @sspdr_phys: physical address of the SSPDR register * @irq: IRQ number used by the driver * @min_rate: minimum clock rate (in Hz) supported by the controller * @max_rate: maximum clock rate (in Hz) supported by the controller @@ -84,6 +88,14 @@ * @rx: current byte in transfer to receive * @fifo_level: how full is FIFO (%0..%SPI_FIFO_SIZE - %1). Receiving one * frame decreases this level and sending one frame increases it. + * @dma_rx: RX DMA channel + * @dma_tx: TX DMA channel + * @dma_rx_data: RX parameters passed to the DMA engine + * @dma_tx_data: TX parameters passed to the DMA engine + * @rx_sgt: sg table for RX transfers + * @tx_sgt: sg table for TX transfers + * @zeropage: dummy page used as RX buffer when only TX buffer is passed in by + * the client * * This structure holds EP93xx SPI controller specific information. When * @running is %true, driver accepts transfer requests from protocol drivers. @@ -100,6 +112,7 @@ struct ep93xx_spi { const struct platform_device *pdev; struct clk *clk; void __iomem *regs_base; + unsigned long sspdr_phys; int irq; unsigned long min_rate; unsigned long max_rate; @@ -112,6 +125,13 @@ struct ep93xx_spi { size_t tx; size_t rx; size_t fifo_level; + struct dma_chan *dma_rx; + struct dma_chan *dma_tx; + struct ep93xx_dma_data dma_rx_data; + struct ep93xx_dma_data dma_tx_data; + struct sg_table rx_sgt; + struct sg_table tx_sgt; + void *zeropage; }; /** @@ -496,14 +516,195 @@ static int ep93xx_spi_read_write(struct ep93xx_spi *espi) espi->fifo_level++; } - if (espi->rx == t->len) { - msg->actual_length += t->len; + if (espi->rx == t->len) return 0; - } return -EINPROGRESS; } +static void ep93xx_spi_pio_transfer(struct ep93xx_spi *espi) +{ + /* + * Now everything is set up for the current transfer. We prime the TX + * FIFO, enable interrupts, and wait for the transfer to complete. + */ + if (ep93xx_spi_read_write(espi)) { + ep93xx_spi_enable_interrupts(espi); + wait_for_completion(&espi->wait); + } +} + +/** + * ep93xx_spi_dma_prepare() - prepares a DMA transfer + * @espi: ep93xx SPI controller struct + * @dir: DMA transfer direction + * + * Function configures the DMA, maps the buffer and prepares the DMA + * descriptor. Returns a valid DMA descriptor in case of success and ERR_PTR + * in case of failure. + */ +static struct dma_async_tx_descriptor * +ep93xx_spi_dma_prepare(struct ep93xx_spi *espi, enum dma_data_direction dir) +{ + struct spi_transfer *t = espi->current_msg->state; + struct dma_async_tx_descriptor *txd; + enum dma_slave_buswidth buswidth; + struct dma_slave_config conf; + struct scatterlist *sg; + struct sg_table *sgt; + struct dma_chan *chan; + const void *buf, *pbuf; + size_t len = t->len; + int i, ret, nents; + + if (bits_per_word(espi) > 8) + buswidth = DMA_SLAVE_BUSWIDTH_2_BYTES; + else + buswidth = DMA_SLAVE_BUSWIDTH_1_BYTE; + + memset(&conf, 0, sizeof(conf)); + conf.direction = dir; + + if (dir == DMA_FROM_DEVICE) { + chan = espi->dma_rx; + buf = t->rx_buf; + sgt = &espi->rx_sgt; + + conf.src_addr = espi->sspdr_phys; + conf.src_addr_width = buswidth; + } else { + chan = espi->dma_tx; + buf = t->tx_buf; + sgt = &espi->tx_sgt; + + conf.dst_addr = espi->sspdr_phys; + conf.dst_addr_width = buswidth; + } + + ret = dmaengine_slave_config(chan, &conf); + if (ret) + return ERR_PTR(ret); + + /* + * We need to split the transfer into PAGE_SIZE'd chunks. This is + * because we are using @espi->zeropage to provide a zero RX buffer + * for the TX transfers and we have only allocated one page for that. + * + * For performance reasons we allocate a new sg_table only when + * needed. Otherwise we will re-use the current one. Eventually the + * last sg_table is released in ep93xx_spi_release_dma(). + */ + + nents = DIV_ROUND_UP(len, PAGE_SIZE); + if (nents != sgt->nents) { + sg_free_table(sgt); + + ret = sg_alloc_table(sgt, nents, GFP_KERNEL); + if (ret) + return ERR_PTR(ret); + } + + pbuf = buf; + for_each_sg(sgt->sgl, sg, sgt->nents, i) { + size_t bytes = min_t(size_t, len, PAGE_SIZE); + + if (buf) { + sg_set_page(sg, virt_to_page(pbuf), bytes, + offset_in_page(pbuf)); + } else { + sg_set_page(sg, virt_to_page(espi->zeropage), + bytes, 0); + } + + pbuf += bytes; + len -= bytes; + } + + if (WARN_ON(len)) { + dev_warn(&espi->pdev->dev, "len = %d expected 0!", len); + return ERR_PTR(-EINVAL); + } + + nents = dma_map_sg(chan->device->dev, sgt->sgl, sgt->nents, dir); + if (!nents) + return ERR_PTR(-ENOMEM); + + txd = chan->device->device_prep_slave_sg(chan, sgt->sgl, nents, + dir, DMA_CTRL_ACK); + if (!txd) { + dma_unmap_sg(chan->device->dev, sgt->sgl, sgt->nents, dir); + return ERR_PTR(-ENOMEM); + } + return txd; +} + +/** + * ep93xx_spi_dma_finish() - finishes with a DMA transfer + * @espi: ep93xx SPI controller struct + * @dir: DMA transfer direction + * + * Function finishes with the DMA transfer. After this, the DMA buffer is + * unmapped. + */ +static void ep93xx_spi_dma_finish(struct ep93xx_spi *espi, + enum dma_data_direction dir) +{ + struct dma_chan *chan; + struct sg_table *sgt; + + if (dir == DMA_FROM_DEVICE) { + chan = espi->dma_rx; + sgt = &espi->rx_sgt; + } else { + chan = espi->dma_tx; + sgt = &espi->tx_sgt; + } + + dma_unmap_sg(chan->device->dev, sgt->sgl, sgt->nents, dir); +} + +static void ep93xx_spi_dma_callback(void *callback_param) +{ + complete(callback_param); +} + +static void ep93xx_spi_dma_transfer(struct ep93xx_spi *espi) +{ + struct spi_message *msg = espi->current_msg; + struct dma_async_tx_descriptor *rxd, *txd; + + rxd = ep93xx_spi_dma_prepare(espi, DMA_FROM_DEVICE); + if (IS_ERR(rxd)) { + dev_err(&espi->pdev->dev, "DMA RX failed: %ld\n", PTR_ERR(rxd)); + msg->status = PTR_ERR(rxd); + return; + } + + txd = ep93xx_spi_dma_prepare(espi, DMA_TO_DEVICE); + if (IS_ERR(txd)) { + ep93xx_spi_dma_finish(espi, DMA_FROM_DEVICE); + dev_err(&espi->pdev->dev, "DMA TX failed: %ld\n", PTR_ERR(rxd)); + msg->status = PTR_ERR(txd); + return; + } + + /* We are ready when RX is done */ + rxd->callback = ep93xx_spi_dma_callback; + rxd->callback_param = &espi->wait; + + /* Now submit both descriptors and wait while they finish */ + dmaengine_submit(rxd); + dmaengine_submit(txd); + + dma_async_issue_pending(espi->dma_rx); + dma_async_issue_pending(espi->dma_tx); + + wait_for_completion(&espi->wait); + + ep93xx_spi_dma_finish(espi, DMA_TO_DEVICE); + ep93xx_spi_dma_finish(espi, DMA_FROM_DEVICE); +} + /** * ep93xx_spi_process_transfer() - processes one SPI transfer * @espi: ep93xx SPI controller struct @@ -556,13 +757,14 @@ static void ep93xx_spi_process_transfer(struct ep93xx_spi *espi, espi->tx = 0; /* - * Now everything is set up for the current transfer. We prime the TX - * FIFO, enable interrupts, and wait for the transfer to complete. + * There is no point of setting up DMA for the transfers which will + * fit into the FIFO and can be transferred with a single interrupt. + * So in these cases we will be using PIO and don't bother for DMA. */ - if (ep93xx_spi_read_write(espi)) { - ep93xx_spi_enable_interrupts(espi); - wait_for_completion(&espi->wait); - } + if (espi->dma_rx && t->len > SPI_FIFO_SIZE) + ep93xx_spi_dma_transfer(espi); + else + ep93xx_spi_pio_transfer(espi); /* * In case of error during transmit, we bail out from processing @@ -571,6 +773,8 @@ static void ep93xx_spi_process_transfer(struct ep93xx_spi *espi, if (msg->status) return; + msg->actual_length += t->len; + /* * After this transfer is finished, perform any possible * post-transfer actions requested by the protocol driver. @@ -752,6 +956,75 @@ static irqreturn_t ep93xx_spi_interrupt(int irq, void *dev_id) return IRQ_HANDLED; } +static bool ep93xx_spi_dma_filter(struct dma_chan *chan, void *filter_param) +{ + if (ep93xx_dma_chan_is_m2p(chan)) + return false; + + chan->private = filter_param; + return true; +} + +static int ep93xx_spi_setup_dma(struct ep93xx_spi *espi) +{ + dma_cap_mask_t mask; + int ret; + + espi->zeropage = (void *)get_zeroed_page(GFP_KERNEL); + if (!espi->zeropage) + return -ENOMEM; + + dma_cap_zero(mask); + dma_cap_set(DMA_SLAVE, mask); + + espi->dma_rx_data.port = EP93XX_DMA_SSP; + espi->dma_rx_data.direction = DMA_FROM_DEVICE; + espi->dma_rx_data.name = "ep93xx-spi-rx"; + + espi->dma_rx = dma_request_channel(mask, ep93xx_spi_dma_filter, + &espi->dma_rx_data); + if (!espi->dma_rx) { + ret = -ENODEV; + goto fail_free_page; + } + + espi->dma_tx_data.port = EP93XX_DMA_SSP; + espi->dma_tx_data.direction = DMA_TO_DEVICE; + espi->dma_tx_data.name = "ep93xx-spi-tx"; + + espi->dma_tx = dma_request_channel(mask, ep93xx_spi_dma_filter, + &espi->dma_tx_data); + if (!espi->dma_tx) { + ret = -ENODEV; + goto fail_release_rx; + } + + return 0; + +fail_release_rx: + dma_release_channel(espi->dma_rx); + espi->dma_rx = NULL; +fail_free_page: + free_page((unsigned long)espi->zeropage); + + return ret; +} + +static void ep93xx_spi_release_dma(struct ep93xx_spi *espi) +{ + if (espi->dma_rx) { + dma_release_channel(espi->dma_rx); + sg_free_table(&espi->rx_sgt); + } + if (espi->dma_tx) { + dma_release_channel(espi->dma_tx); + sg_free_table(&espi->tx_sgt); + } + + if (espi->zeropage) + free_page((unsigned long)espi->zeropage); +} + static int __init ep93xx_spi_probe(struct platform_device *pdev) { struct spi_master *master; @@ -818,6 +1091,7 @@ static int __init ep93xx_spi_probe(struct platform_device *pdev) goto fail_put_clock; } + espi->sspdr_phys = res->start + SSPDR; espi->regs_base = ioremap(res->start, resource_size(res)); if (!espi->regs_base) { dev_err(&pdev->dev, "failed to map resources\n"); @@ -832,10 +1106,13 @@ static int __init ep93xx_spi_probe(struct platform_device *pdev) goto fail_unmap_regs; } + if (info->use_dma && ep93xx_spi_setup_dma(espi)) + dev_warn(&pdev->dev, "DMA setup failed. Falling back to PIO\n"); + espi->wq = create_singlethread_workqueue("ep93xx_spid"); if (!espi->wq) { dev_err(&pdev->dev, "unable to create workqueue\n"); - goto fail_free_irq; + goto fail_free_dma; } INIT_WORK(&espi->msg_work, ep93xx_spi_work); INIT_LIST_HEAD(&espi->msg_queue); @@ -857,7 +1134,8 @@ static int __init ep93xx_spi_probe(struct platform_device *pdev) fail_free_queue: destroy_workqueue(espi->wq); -fail_free_irq: +fail_free_dma: + ep93xx_spi_release_dma(espi); free_irq(espi->irq, espi); fail_unmap_regs: iounmap(espi->regs_base); @@ -901,6 +1179,7 @@ static int __exit ep93xx_spi_remove(struct platform_device *pdev) } spin_unlock_irq(&espi->lock); + ep93xx_spi_release_dma(espi); free_irq(espi->irq, espi); iounmap(espi->regs_base); res = platform_get_resource(pdev, IORESOURCE_MEM, 0); |