diff options
Diffstat (limited to 'drivers/spi')
| -rw-r--r-- | drivers/spi/spi-atmel.c | 587 |
1 files changed, 566 insertions, 21 deletions
diff --git a/drivers/spi/spi-atmel.c b/drivers/spi/spi-atmel.c index 3625951e5df..787bd2c22bc 100644 --- a/drivers/spi/spi-atmel.c +++ b/drivers/spi/spi-atmel.c @@ -15,11 +15,13 @@ #include <linux/platform_device.h> #include <linux/delay.h> #include <linux/dma-mapping.h> +#include <linux/dmaengine.h> #include <linux/err.h> #include <linux/interrupt.h> #include <linux/spi/spi.h> #include <linux/slab.h> #include <linux/platform_data/atmel.h> +#include <linux/platform_data/dma-atmel.h> #include <linux/of.h> #include <linux/io.h> @@ -182,6 +184,22 @@ #define spi_writel(port,reg,value) \ __raw_writel((value), (port)->regs + SPI_##reg) +/* use PIO for small transfers, avoiding DMA setup/teardown overhead and + * cache operations; better heuristics consider wordsize and bitrate. + */ +#define DMA_MIN_BYTES 16 + +struct atmel_spi_dma { + struct dma_chan *chan_rx; + struct dma_chan *chan_tx; + struct scatterlist sgrx; + struct scatterlist sgtx; + struct dma_async_tx_descriptor *data_desc_rx; + struct dma_async_tx_descriptor *data_desc_tx; + + struct at_dma_slave dma_slave; +}; + struct atmel_spi_caps { bool is_spi2; bool has_wdrbt; @@ -206,16 +224,23 @@ struct atmel_spi { u8 stopping; struct list_head queue; + struct tasklet_struct tasklet; struct spi_transfer *current_transfer; unsigned long current_remaining_bytes; struct spi_transfer *next_transfer; unsigned long next_remaining_bytes; int done_status; + /* scratch buffer */ void *buffer; dma_addr_t buffer_dma; struct atmel_spi_caps caps; + + bool use_dma; + bool use_pdc; + /* dmaengine data */ + struct atmel_spi_dma dma; }; /* Controller-specific per-slave state */ @@ -284,6 +309,7 @@ static void cs_activate(struct atmel_spi *as, struct spi_device *spi) | SPI_BIT(MODFDIS) | SPI_BIT(MSTR)); } + mr = spi_readl(as, MR); gpio_set_value(asd->npcs_pin, active); } else { @@ -344,6 +370,12 @@ static void atmel_spi_unlock(struct atmel_spi *as) spin_unlock_irqrestore(&as->lock, as->flags); } +static inline bool atmel_spi_use_dma(struct atmel_spi *as, + struct spi_transfer *xfer) +{ + return as->use_dma && xfer->len >= DMA_MIN_BYTES; +} + static inline int atmel_spi_xfer_is_last(struct spi_message *msg, struct spi_transfer *xfer) { @@ -355,6 +387,265 @@ static inline int atmel_spi_xfer_can_be_chained(struct spi_transfer *xfer) return xfer->delay_usecs == 0 && !xfer->cs_change; } +static int atmel_spi_dma_slave_config(struct atmel_spi *as, + struct dma_slave_config *slave_config, + u8 bits_per_word) +{ + int err = 0; + + if (bits_per_word > 8) { + slave_config->dst_addr_width = DMA_SLAVE_BUSWIDTH_2_BYTES; + slave_config->src_addr_width = DMA_SLAVE_BUSWIDTH_2_BYTES; + } else { + slave_config->dst_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE; + slave_config->src_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE; + } + + slave_config->dst_addr = (dma_addr_t)as->phybase + SPI_TDR; + slave_config->src_addr = (dma_addr_t)as->phybase + SPI_RDR; + slave_config->src_maxburst = 1; + slave_config->dst_maxburst = 1; + slave_config->device_fc = false; + + slave_config->direction = DMA_MEM_TO_DEV; + if (dmaengine_slave_config(as->dma.chan_tx, slave_config)) { + dev_err(&as->pdev->dev, + "failed to configure tx dma channel\n"); + err = -EINVAL; + } + + slave_config->direction = DMA_DEV_TO_MEM; + if (dmaengine_slave_config(as->dma.chan_rx, slave_config)) { + dev_err(&as->pdev->dev, + "failed to configure rx dma channel\n"); + err = -EINVAL; + } + + return err; +} + +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 atmel_spi_configure_dma(struct atmel_spi *as) +{ + struct at_dma_slave *sdata = &as->dma.dma_slave; + struct dma_slave_config slave_config; + int err; + + if (sdata && sdata->dma_dev) { + dma_cap_mask_t mask; + + /* Try to grab two DMA channels */ + dma_cap_zero(mask); + dma_cap_set(DMA_SLAVE, mask); + as->dma.chan_tx = dma_request_channel(mask, filter, sdata); + if (as->dma.chan_tx) + as->dma.chan_rx = + dma_request_channel(mask, filter, sdata); + } + if (!as->dma.chan_rx || !as->dma.chan_tx) { + dev_err(&as->pdev->dev, + "DMA channel not available, SPI unable to use DMA\n"); + err = -EBUSY; + goto error; + } + + err = atmel_spi_dma_slave_config(as, &slave_config, 8); + if (err) + goto error; + + dev_info(&as->pdev->dev, + "Using %s (tx) and %s (rx) for DMA transfers\n", + dma_chan_name(as->dma.chan_tx), + dma_chan_name(as->dma.chan_rx)); + return 0; +error: + if (as->dma.chan_rx) + dma_release_channel(as->dma.chan_rx); + if (as->dma.chan_tx) + dma_release_channel(as->dma.chan_tx); + return err; +} + +static void atmel_spi_stop_dma(struct atmel_spi *as) +{ + if (as->dma.chan_rx) + as->dma.chan_rx->device->device_control(as->dma.chan_rx, + DMA_TERMINATE_ALL, 0); + if (as->dma.chan_tx) + as->dma.chan_tx->device->device_control(as->dma.chan_tx, + DMA_TERMINATE_ALL, 0); +} + +static void atmel_spi_release_dma(struct atmel_spi *as) +{ + if (as->dma.chan_rx) + dma_release_channel(as->dma.chan_rx); + if (as->dma.chan_tx) + dma_release_channel(as->dma.chan_tx); +} + +/* This function is called by the DMA driver from tasklet context */ +static void dma_callback(void *data) +{ + struct spi_master *master = data; + struct atmel_spi *as = spi_master_get_devdata(master); + + /* trigger SPI tasklet */ + tasklet_schedule(&as->tasklet); +} + +/* + * Next transfer using PIO. + * lock is held, spi tasklet is blocked + */ +static void atmel_spi_next_xfer_pio(struct spi_master *master, + struct spi_transfer *xfer) +{ + struct atmel_spi *as = spi_master_get_devdata(master); + + dev_vdbg(master->dev.parent, "atmel_spi_next_xfer_pio\n"); + + as->current_remaining_bytes = xfer->len; + + /* Make sure data is not remaining in RDR */ + spi_readl(as, RDR); + while (spi_readl(as, SR) & SPI_BIT(RDRF)) { + spi_readl(as, RDR); + cpu_relax(); + } + + if (xfer->tx_buf) + spi_writel(as, TDR, *(u8 *)(xfer->tx_buf)); + else + spi_writel(as, TDR, 0); + + dev_dbg(master->dev.parent, + " start pio xfer %p: len %u tx %p rx %p\n", + xfer, xfer->len, xfer->tx_buf, xfer->rx_buf); + + /* Enable relevant interrupts */ + spi_writel(as, IER, SPI_BIT(RDRF) | SPI_BIT(OVRES)); +} + +/* + * Submit next transfer for DMA. + * lock is held, spi tasklet is blocked + */ +static int atmel_spi_next_xfer_dma_submit(struct spi_master *master, + struct spi_transfer *xfer, + u32 *plen) +{ + struct atmel_spi *as = spi_master_get_devdata(master); + struct dma_chan *rxchan = as->dma.chan_rx; + struct dma_chan *txchan = as->dma.chan_tx; + struct dma_async_tx_descriptor *rxdesc; + struct dma_async_tx_descriptor *txdesc; + struct dma_slave_config slave_config; + dma_cookie_t cookie; + u32 len = *plen; + + dev_vdbg(master->dev.parent, "atmel_spi_next_xfer_dma_submit\n"); + + /* Check that the channels are available */ + if (!rxchan || !txchan) + return -ENODEV; + + /* release lock for DMA operations */ + atmel_spi_unlock(as); + + /* prepare the RX dma transfer */ + sg_init_table(&as->dma.sgrx, 1); + if (xfer->rx_buf) { + as->dma.sgrx.dma_address = xfer->rx_dma + xfer->len - *plen; + } else { + as->dma.sgrx.dma_address = as->buffer_dma; + if (len > BUFFER_SIZE) + len = BUFFER_SIZE; + } + + /* prepare the TX dma transfer */ + sg_init_table(&as->dma.sgtx, 1); + if (xfer->tx_buf) { + as->dma.sgtx.dma_address = xfer->tx_dma + xfer->len - *plen; + } else { + as->dma.sgtx.dma_address = as->buffer_dma; + if (len > BUFFER_SIZE) + len = BUFFER_SIZE; + memset(as->buffer, 0, len); + } + + sg_dma_len(&as->dma.sgtx) = len; + sg_dma_len(&as->dma.sgrx) = len; + + *plen = len; + + if (atmel_spi_dma_slave_config(as, &slave_config, 8)) + goto err_exit; + + /* Send both scatterlists */ + rxdesc = rxchan->device->device_prep_slave_sg(rxchan, + &as->dma.sgrx, + 1, + DMA_FROM_DEVICE, + DMA_PREP_INTERRUPT | DMA_CTRL_ACK, + NULL); + if (!rxdesc) + goto err_dma; + + txdesc = txchan->device->device_prep_slave_sg(txchan, + &as->dma.sgtx, + 1, + DMA_TO_DEVICE, + DMA_PREP_INTERRUPT | DMA_CTRL_ACK, + NULL); + if (!txdesc) + goto err_dma; + + dev_dbg(master->dev.parent, + " start dma xfer %p: len %u tx %p/%08x rx %p/%08x\n", + xfer, xfer->len, xfer->tx_buf, xfer->tx_dma, + xfer->rx_buf, xfer->rx_dma); + + /* Enable relevant interrupts */ + spi_writel(as, IER, SPI_BIT(OVRES)); + + /* Put the callback on the RX transfer only, that should finish last */ + rxdesc->callback = dma_callback; + rxdesc->callback_param = master; + + /* Submit and fire RX and TX with TX last so we're ready to read! */ + cookie = rxdesc->tx_submit(rxdesc); + if (dma_submit_error(cookie)) + goto err_dma; + cookie = txdesc->tx_submit(txdesc); + if (dma_submit_error(cookie)) + goto err_dma; + rxchan->device->device_issue_pending(rxchan); + txchan->device->device_issue_pending(txchan); + + /* take back lock */ + atmel_spi_lock(as); + return 0; + +err_dma: + spi_writel(as, IDR, SPI_BIT(OVRES)); + atmel_spi_stop_dma(as); +err_exit: + atmel_spi_lock(as); + return -ENOMEM; +} + static void atmel_spi_next_xfer_data(struct spi_master *master, struct spi_transfer *xfer, dma_addr_t *tx_dma, @@ -372,6 +663,7 @@ static void atmel_spi_next_xfer_data(struct spi_master *master, if (len > BUFFER_SIZE) len = BUFFER_SIZE; } + if (xfer->tx_buf) *tx_dma = xfer->tx_dma + xfer->len - *plen; else { @@ -387,10 +679,10 @@ static void atmel_spi_next_xfer_data(struct spi_master *master, } /* - * Submit next transfer for DMA. + * Submit next transfer for PDC. * lock is held, spi irq is blocked */ -static void atmel_spi_next_xfer(struct spi_master *master, +static void atmel_spi_pdc_next_xfer(struct spi_master *master, struct spi_message *msg) { struct atmel_spi *as = spi_master_get_devdata(master); @@ -487,6 +779,48 @@ static void atmel_spi_next_xfer(struct spi_master *master, spi_writel(as, PTCR, SPI_BIT(TXTEN) | SPI_BIT(RXTEN)); } +/* + * Choose way to submit next transfer and start it. + * lock is held, spi tasklet is blocked + */ +static void atmel_spi_dma_next_xfer(struct spi_master *master, + struct spi_message *msg) +{ + struct atmel_spi *as = spi_master_get_devdata(master); + struct spi_transfer *xfer; + u32 remaining, len; + + remaining = as->current_remaining_bytes; + if (remaining) { + xfer = as->current_transfer; + len = remaining; + } else { + if (!as->current_transfer) + xfer = list_entry(msg->transfers.next, + struct spi_transfer, transfer_list); + else + xfer = list_entry( + as->current_transfer->transfer_list.next, + struct spi_transfer, transfer_list); + + as->current_transfer = xfer; + len = xfer->len; + } + + if (atmel_spi_use_dma(as, xfer)) { + u32 total = len; + if (!atmel_spi_next_xfer_dma_submit(master, xfer, &len)) { + as->current_remaining_bytes = total - len; + return; + } else { + dev_err(&msg->spi->dev, "unable to use DMA, fallback to PIO\n"); + } + } + + /* use PIO if error appened using DMA */ + atmel_spi_next_xfer_pio(master, xfer); +} + static void atmel_spi_next_message(struct spi_master *master) { struct atmel_spi *as = spi_master_get_devdata(master); @@ -511,7 +845,10 @@ static void atmel_spi_next_message(struct spi_master *master) } else cs_activate(as, spi); - atmel_spi_next_xfer(master, msg); + if (as->use_pdc) + atmel_spi_pdc_next_xfer(master, msg); + else + atmel_spi_dma_next_xfer(master, msg); } /* @@ -564,6 +901,11 @@ static void atmel_spi_dma_unmap_xfer(struct spi_master *master, xfer->len, DMA_FROM_DEVICE); } +static void atmel_spi_disable_pdc_transfer(struct atmel_spi *as) +{ + spi_writel(as, PTCR, SPI_BIT(RXTDIS) | SPI_BIT(TXTDIS)); +} + static void atmel_spi_msg_done(struct spi_master *master, struct atmel_spi *as, struct spi_message *msg, int stay) @@ -589,14 +931,183 @@ atmel_spi_msg_done(struct spi_master *master, struct atmel_spi *as, as->done_status = 0; /* continue if needed */ - if (list_empty(&as->queue) || as->stopping) - spi_writel(as, PTCR, SPI_BIT(RXTDIS) | SPI_BIT(TXTDIS)); - else + if (list_empty(&as->queue) || as->stopping) { + if (as->use_pdc) + atmel_spi_disable_pdc_transfer(as); + } else { atmel_spi_next_message(master); + } +} + +/* Called from IRQ + * lock is held + * + * Must update "current_remaining_bytes" to keep track of data + * to transfer. + */ +static void +atmel_spi_pump_pio_data(struct atmel_spi *as, struct spi_transfer *xfer) +{ + u8 *txp; + u8 *rxp; + unsigned long xfer_pos = xfer->len - as->current_remaining_bytes; + + if (xfer->rx_buf) { + rxp = ((u8 *)xfer->rx_buf) + xfer_pos; + *rxp = spi_readl(as, RDR); + } else { + spi_readl(as, RDR); + } + + as->current_remaining_bytes--; + + if (as->current_remaining_bytes) { + if (xfer->tx_buf) { + txp = ((u8 *)xfer->tx_buf) + xfer_pos + 1; + spi_writel(as, TDR, *txp); + } else { + spi_writel(as, TDR, 0); + } + } +} + +/* Tasklet + * Called from DMA callback + pio transfer and overrun IRQ. + */ +static void atmel_spi_tasklet_func(unsigned long data) +{ + struct spi_master *master = (struct spi_master *)data; + struct atmel_spi *as = spi_master_get_devdata(master); + struct spi_message *msg; + struct spi_transfer *xfer; + + dev_vdbg(master->dev.parent, "atmel_spi_tasklet_func\n"); + + atmel_spi_lock(as); + + xfer = as->current_transfer; + + if (xfer == NULL) + /* already been there */ + goto tasklet_out; + + msg = list_entry(as->queue.next, struct spi_message, queue); + + if (as->current_remaining_bytes == 0) { + if (as->done_status < 0) { + /* error happened (overrun) */ + if (atmel_spi_use_dma(as, xfer)) + atmel_spi_stop_dma(as); + } else { + /* only update length if no error */ + msg->actual_length += xfer->len; + } + + if (atmel_spi_use_dma(as, xfer)) + if (!msg->is_dma_mapped) + atmel_spi_dma_unmap_xfer(master, xfer); + + if (xfer->delay_usecs) + udelay(xfer->delay_usecs); + + if (atmel_spi_xfer_is_last(msg, xfer) || as->done_status < 0) { + /* report completed (or erroneous) message */ + atmel_spi_msg_done(master, as, msg, xfer->cs_change); + } else { + if (xfer->cs_change) { + cs_deactivate(as, msg->spi); + udelay(1); + cs_activate(as, msg->spi); + } + + /* + * Not done yet. Submit the next transfer. + * + * FIXME handle protocol options for xfer + */ + atmel_spi_dma_next_xfer(master, msg); + } + } else { + /* + * Keep going, we still have data to send in + * the current transfer. + */ + atmel_spi_dma_next_xfer(master, msg); + } + +tasklet_out: + atmel_spi_unlock(as); +} + +/* Interrupt + * + * No need for locking in this Interrupt handler: done_status is the + * only information modified. What we need is the update of this field + * before tasklet runs. This is ensured by using barrier. + */ +static irqreturn_t +atmel_spi_pio_interrupt(int irq, void *dev_id) +{ + struct spi_master *master = dev_id; + struct atmel_spi *as = spi_master_get_devdata(master); + u32 status, pending, imr; + struct spi_transfer *xfer; + int ret = IRQ_NONE; + + imr = spi_readl(as, IMR); + status = spi_readl(as, SR); + pending = status & imr; + + if (pending & SPI_BIT(OVRES)) { + ret = IRQ_HANDLED; + spi_writel(as, IDR, SPI_BIT(OVRES)); + dev_warn(master->dev.parent, "overrun\n"); + + /* + * When we get an overrun, we disregard the current + * transfer. Data will not be copied back from any + * bounce buffer and msg->actual_len will not be + * updated with the last xfer. + * + * We will also not process any remaning transfers in + * the message. + * + * All actions are done in tasklet with done_status indication + */ + as->done_status = -EIO; + smp_wmb(); + + /* Clear any overrun happening while cleaning up */ + spi_readl(as, SR); + + tasklet_schedule(&as->tasklet); + + } else if (pending & SPI_BIT(RDRF)) { + atmel_spi_lock(as); + + if (as->current_remaining_bytes) { + ret = IRQ_HANDLED; + xfer = as->current_transfer; + atmel_spi_pump_pio_data(as, xfer); + if (!as->current_remaining_bytes) { + /* no more data to xfer, kick tasklet */ + spi_writel(as, IDR, pending); + tasklet_schedule(&as->tasklet); + } + } + + atmel_spi_unlock(as); + } else { + WARN_ONCE(pending, "IRQ not handled, pending = %x\n", pending); + ret = IRQ_HANDLED; + spi_writel(as, IDR, pending); + } + + return ret; } static irqreturn_t -atmel_spi_interrupt(int irq, void *dev_id) +atmel_spi_pdc_interrupt(int irq, void *dev_id) { struct spi_master *master = dev_id; struct atmel_spi *as = spi_master_get_devdata(master); @@ -697,14 +1208,14 @@ atmel_spi_interrupt(int irq, void *dev_id) * * FIXME handle protocol options for xfer */ - atmel_spi_next_xfer(master, msg); + atmel_spi_pdc_next_xfer(master, msg); } } else { /* * Keep going, we still have data to send in * the current transfer. */ - atmel_spi_next_xfer(master, msg); + atmel_spi_pdc_next_xfer(master, msg); } } @@ -875,13 +1386,10 @@ static int atmel_spi_transfer(struct spi_device *spi, struct spi_message *msg) /* * DMA map early, for performance (empties dcache ASAP) and - * better fault reporting. This is a DMA-only driver. - * - * NOTE that if dma_unmap_single() ever starts to do work on - * platforms supported by this driver, we would need to clean - * up mappings for previously-mapped transfers. + * better fault reporting. */ - if (!msg->is_dma_mapped) { + if ((!msg->is_dma_mapped) && (atmel_spi_use_dma(as, xfer) + || as->use_pdc)) { if (atmel_spi_dma_map_xfer(as, xfer) < 0) return -ENOMEM; } @@ -1000,6 +1508,7 @@ static int atmel_spi_probe(struct platform_device *pdev) spin_lock_init(&as->lock); INIT_LIST_HEAD(&as->queue); + as->pdev = pdev; as->regs = ioremap(regs->start, resource_size(regs)); if (!as->regs) @@ -1010,8 +1519,28 @@ static int atmel_spi_probe(struct platform_device *pdev) atmel_get_caps(as); - ret = request_irq(irq, atmel_spi_interrupt, 0, - dev_name(&pdev->dev), master); + as->use_dma = false; + as->use_pdc = false; + if (as->caps.has_dma_support) { + if (atmel_spi_configure_dma(as) == 0) + as->use_dma = true; + } else { + as->use_pdc = true; + } + + if (as->caps.has_dma_support && !as->use_dma) + dev_info(&pdev->dev, "Atmel SPI Controller using PIO only\n"); + + if (as->use_pdc) { + ret = request_irq(irq, atmel_spi_pdc_interrupt, 0, + dev_name(&pdev->dev), master); + } else { + tasklet_init(&as->tasklet, atmel_spi_tasklet_func, + (unsigned long)master); + + ret = request_irq(irq, atmel_spi_pio_interrupt, 0, + dev_name(&pdev->dev), master); + } if (ret) goto out_unmap_regs; @@ -1025,7 +1554,9 @@ static int atmel_spi_probe(struct platform_device *pdev) } else { spi_writel(as, MR, SPI_BIT(MSTR) | SPI_BIT(MODFDIS)); } - spi_writel(as, PTCR, SPI_BIT(RXTDIS) | SPI_BIT(TXTDIS)); + + if (as->use_pdc) + spi_writel(as, PTCR, SPI_BIT(RXTDIS) | SPI_BIT(TXTDIS)); spi_writel(as, CR, SPI_BIT(SPIEN)); /* go! */ @@ -1034,11 +1565,14 @@ static int atmel_spi_probe(struct platform_device *pdev) ret = spi_register_master(master); if (ret) - goto out_reset_hw; + goto out_free_dma; return 0; -out_reset_hw: +out_free_dma: + if (as->use_dma) + atmel_spi_release_dma(as); + spi_writel(as, CR, SPI_BIT(SWRST)); spi_writel(as, CR, SPI_BIT(SWRST)); /* AT91SAM9263 Rev B workaround */ clk_disable(clk); @@ -1046,6 +1580,8 @@ out_reset_hw: out_unmap_regs: iounmap(as->regs); out_free_buffer: + if (!as->use_pdc) + tasklet_kill(&as->tasklet); dma_free_coherent(&pdev->dev, BUFFER_SIZE, as->buffer, as->buffer_dma); out_free: @@ -1064,6 +1600,11 @@ static int atmel_spi_remove(struct platform_device *pdev) /* reset the hardware and block queue progress */ spin_lock_irq(&as->lock); as->stopping = 1; + if (as->use_dma) { + atmel_spi_stop_dma(as); + atmel_spi_release_dma(as); + } + spi_writel(as, CR, SPI_BIT(SWRST)); spi_writel(as, CR, SPI_BIT(SWRST)); /* AT91SAM9263 Rev B workaround */ spi_readl(as, SR); @@ -1072,13 +1613,17 @@ static int atmel_spi_remove(struct platform_device *pdev) /* Terminate remaining queued transfers */ list_for_each_entry(msg, &as->queue, queue) { list_for_each_entry(xfer, &msg->transfers, transfer_list) { - if (!msg->is_dma_mapped) + if (!msg->is_dma_mapped + && (atmel_spi_use_dma(as, xfer) + || as->use_pdc)) atmel_spi_dma_unmap_xfer(master, xfer); } msg->status = -ESHUTDOWN; msg->complete(msg->context); } + if (!as->use_pdc) + tasklet_kill(&as->tasklet); dma_free_coherent(&pdev->dev, BUFFER_SIZE, as->buffer, as->buffer_dma); |