diff options
Diffstat (limited to 'drivers')
| -rw-r--r-- | drivers/mmc/host/Kconfig | 11 | ||||
| -rw-r--r-- | drivers/mmc/host/atmel-mci.c | 274 |
2 files changed, 269 insertions, 16 deletions
diff --git a/drivers/mmc/host/Kconfig b/drivers/mmc/host/Kconfig index ea8d7a3490d..1ce21d4c860 100644 --- a/drivers/mmc/host/Kconfig +++ b/drivers/mmc/host/Kconfig @@ -114,6 +114,17 @@ config MMC_ATMELMCI If unsure, say N. +config MMC_ATMELMCI_DMA + bool "Atmel MCI DMA support (EXPERIMENTAL)" + depends on MMC_ATMELMCI && DMA_ENGINE && EXPERIMENTAL + help + Say Y here to have the Atmel MCI driver use a DMA engine to + do data transfers and thus increase the throughput and + reduce the CPU utilization. Note that this is highly + experimental and may cause the driver to lock up. + + If unsure, say N. + config MMC_IMX tristate "Motorola i.MX Multimedia Card Interface support" depends on ARCH_IMX diff --git a/drivers/mmc/host/atmel-mci.c b/drivers/mmc/host/atmel-mci.c index d8ab35175a5..d45dfa25938 100644 --- a/drivers/mmc/host/atmel-mci.c +++ b/drivers/mmc/host/atmel-mci.c @@ -11,6 +11,8 @@ #include <linux/clk.h> #include <linux/debugfs.h> #include <linux/device.h> +#include <linux/dmaengine.h> +#include <linux/dma-mapping.h> #include <linux/err.h> #include <linux/gpio.h> #include <linux/init.h> @@ -33,6 +35,7 @@ #include "atmel-mci-regs.h" #define ATMCI_DATA_ERROR_FLAGS (MCI_DCRCE | MCI_DTOE | MCI_OVRE | MCI_UNRE) +#define ATMCI_DMA_THRESHOLD 16 enum { EVENT_CMD_COMPLETE = 0, @@ -50,6 +53,14 @@ enum atmel_mci_state { STATE_DATA_ERROR, }; +struct atmel_mci_dma { +#ifdef CONFIG_MMC_ATMELMCI_DMA + struct dma_client client; + struct dma_chan *chan; + struct dma_async_tx_descriptor *data_desc; +#endif +}; + /** * struct atmel_mci - MMC controller state shared between all slots * @lock: Spinlock protecting the queue and associated data. @@ -62,6 +73,8 @@ enum atmel_mci_state { * @cmd: The command currently being sent to the card, or NULL. * @data: The data currently being transferred, or NULL if no data * transfer is in progress. + * @dma: DMA client state. + * @data_chan: DMA channel being used for the current data transfer. * @cmd_status: Snapshot of SR taken upon completion of the current * command. Only valid when EVENT_CMD_COMPLETE is pending. * @data_status: Snapshot of SR taken upon completion of the current @@ -126,6 +139,9 @@ struct atmel_mci { struct mmc_command *cmd; struct mmc_data *data; + struct atmel_mci_dma dma; + struct dma_chan *data_chan; + u32 cmd_status; u32 data_status; u32 stop_cmdr; @@ -485,6 +501,144 @@ static void send_stop_cmd(struct atmel_mci *host, struct mmc_data *data) mci_writel(host, IER, MCI_CMDRDY); } +#ifdef CONFIG_MMC_ATMELMCI_DMA +static void atmci_dma_cleanup(struct atmel_mci *host) +{ + struct mmc_data *data = host->data; + + dma_unmap_sg(&host->pdev->dev, data->sg, data->sg_len, + ((data->flags & MMC_DATA_WRITE) + ? DMA_TO_DEVICE : DMA_FROM_DEVICE)); +} + +static void atmci_stop_dma(struct atmel_mci *host) +{ + struct dma_chan *chan = host->data_chan; + + if (chan) { + chan->device->device_terminate_all(chan); + atmci_dma_cleanup(host); + } else { + /* Data transfer was stopped by the interrupt handler */ + atmci_set_pending(host, EVENT_XFER_COMPLETE); + mci_writel(host, IER, MCI_NOTBUSY); + } +} + +/* This function is called by the DMA driver from tasklet context. */ +static void atmci_dma_complete(void *arg) +{ + struct atmel_mci *host = arg; + struct mmc_data *data = host->data; + + dev_vdbg(&host->pdev->dev, "DMA complete\n"); + + atmci_dma_cleanup(host); + + /* + * If the card was removed, data will be NULL. No point trying + * to send the stop command or waiting for NBUSY in this case. + */ + if (data) { + atmci_set_pending(host, EVENT_XFER_COMPLETE); + tasklet_schedule(&host->tasklet); + + /* + * Regardless of what the documentation says, we have + * to wait for NOTBUSY even after block read + * operations. + * + * When the DMA transfer is complete, the controller + * may still be reading the CRC from the card, i.e. + * the data transfer is still in progress and we + * haven't seen all the potential error bits yet. + * + * The interrupt handler will schedule a different + * tasklet to finish things up when the data transfer + * is completely done. + * + * We may not complete the mmc request here anyway + * because the mmc layer may call back and cause us to + * violate the "don't submit new operations from the + * completion callback" rule of the dma engine + * framework. + */ + mci_writel(host, IER, MCI_NOTBUSY); + } +} + +static int +atmci_submit_data_dma(struct atmel_mci *host, struct mmc_data *data) +{ + struct dma_chan *chan; + struct dma_async_tx_descriptor *desc; + struct scatterlist *sg; + unsigned int i; + enum dma_data_direction direction; + + /* + * We don't do DMA on "complex" transfers, i.e. with + * non-word-aligned buffers or lengths. Also, we don't bother + * with all the DMA setup overhead for short transfers. + */ + if (data->blocks * data->blksz < ATMCI_DMA_THRESHOLD) + return -EINVAL; + if (data->blksz & 3) + return -EINVAL; + + for_each_sg(data->sg, sg, data->sg_len, i) { + if (sg->offset & 3 || sg->length & 3) + return -EINVAL; + } + + /* If we don't have a channel, we can't do DMA */ + chan = host->dma.chan; + if (chan) { + dma_chan_get(chan); + host->data_chan = chan; + } + + if (!chan) + return -ENODEV; + + if (data->flags & MMC_DATA_READ) + direction = DMA_FROM_DEVICE; + else + direction = DMA_TO_DEVICE; + + desc = chan->device->device_prep_slave_sg(chan, + data->sg, data->sg_len, direction, + DMA_PREP_INTERRUPT | DMA_CTRL_ACK); + if (!desc) + return -ENOMEM; + + host->dma.data_desc = desc; + desc->callback = atmci_dma_complete; + desc->callback_param = host; + desc->tx_submit(desc); + + /* Go! */ + chan->device->device_issue_pending(chan); + + return 0; +} + +#else /* CONFIG_MMC_ATMELMCI_DMA */ + +static int atmci_submit_data_dma(struct atmel_mci *host, struct mmc_data *data) +{ + return -ENOSYS; +} + +static void atmci_stop_dma(struct atmel_mci *host) +{ + /* Data transfer was stopped by the interrupt handler */ + atmci_set_pending(host, EVENT_XFER_COMPLETE); + mci_writel(host, IER, MCI_NOTBUSY); +} + +#endif /* CONFIG_MMC_ATMELMCI_DMA */ + /* * Returns a mask of interrupt flags to be enabled after the whole * request has been prepared. @@ -500,24 +654,27 @@ static u32 atmci_submit_data(struct atmel_mci *host, struct mmc_data *data) host->data = data; iflags = ATMCI_DATA_ERROR_FLAGS; + if (atmci_submit_data_dma(host, data)) { + host->data_chan = NULL; - /* - * Errata: MMC data write operation with less than 12 - * bytes is impossible. - * - * Errata: MCI Transmit Data Register (TDR) FIFO - * corruption when length is not multiple of 4. - */ - if (data->blocks * data->blksz < 12 - || (data->blocks * data->blksz) & 3) - host->need_reset = true; + /* + * Errata: MMC data write operation with less than 12 + * bytes is impossible. + * + * Errata: MCI Transmit Data Register (TDR) FIFO + * corruption when length is not multiple of 4. + */ + if (data->blocks * data->blksz < 12 + || (data->blocks * data->blksz) & 3) + host->need_reset = true; - host->sg = data->sg; - host->pio_offset = 0; - if (data->flags & MMC_DATA_READ) - iflags |= MCI_RXRDY; - else - iflags |= MCI_TXRDY; + host->sg = data->sg; + host->pio_offset = 0; + if (data->flags & MMC_DATA_READ) + iflags |= MCI_RXRDY; + else + iflags |= MCI_TXRDY; + } return iflags; } @@ -848,6 +1005,7 @@ static void atmci_command_complete(struct atmel_mci *host, if (cmd->data) { host->data = NULL; + atmci_stop_dma(host); mci_writel(host, IDR, MCI_NOTBUSY | MCI_TXRDY | MCI_RXRDY | ATMCI_DATA_ERROR_FLAGS); @@ -917,6 +1075,7 @@ static void atmci_detect_change(unsigned long data) /* fall through */ case STATE_SENDING_DATA: mrq->data->error = -ENOMEDIUM; + atmci_stop_dma(host); break; case STATE_DATA_BUSY: case STATE_DATA_ERROR: @@ -995,6 +1154,7 @@ static void atmci_tasklet_func(unsigned long priv) case STATE_SENDING_DATA: if (atmci_test_and_clear_pending(host, EVENT_DATA_ERROR)) { + atmci_stop_dma(host); if (data->stop) send_stop_cmd(host, data); state = STATE_DATA_ERROR; @@ -1280,6 +1440,60 @@ static irqreturn_t atmci_detect_interrupt(int irq, void *dev_id) return IRQ_HANDLED; } +#ifdef CONFIG_MMC_ATMELMCI_DMA + +static inline struct atmel_mci * +dma_client_to_atmel_mci(struct dma_client *client) +{ + return container_of(client, struct atmel_mci, dma.client); +} + +static enum dma_state_client atmci_dma_event(struct dma_client *client, + struct dma_chan *chan, enum dma_state state) +{ + struct atmel_mci *host; + enum dma_state_client ret = DMA_NAK; + + host = dma_client_to_atmel_mci(client); + + switch (state) { + case DMA_RESOURCE_AVAILABLE: + spin_lock_bh(&host->lock); + if (!host->dma.chan) { + host->dma.chan = chan; + ret = DMA_ACK; + } + spin_unlock_bh(&host->lock); + + if (ret == DMA_ACK) + dev_info(&host->pdev->dev, + "Using %s for DMA transfers\n", + chan->dev.bus_id); + break; + + case DMA_RESOURCE_REMOVED: + spin_lock_bh(&host->lock); + if (host->dma.chan == chan) { + host->dma.chan = NULL; + ret = DMA_ACK; + } + spin_unlock_bh(&host->lock); + + if (ret == DMA_ACK) + dev_info(&host->pdev->dev, + "Lost %s, falling back to PIO\n", + chan->dev.bus_id); + break; + + default: + break; + } + + + return ret; +} +#endif /* CONFIG_MMC_ATMELMCI_DMA */ + static int __init atmci_init_slot(struct atmel_mci *host, struct mci_slot_pdata *slot_data, unsigned int id, u32 sdc_reg) @@ -1434,6 +1648,25 @@ static int __init atmci_probe(struct platform_device *pdev) if (ret) goto err_request_irq; +#ifdef CONFIG_MMC_ATMELMCI_DMA + if (pdata->dma_slave) { + struct dma_slave *slave = pdata->dma_slave; + + slave->tx_reg = regs->start + MCI_TDR; + slave->rx_reg = regs->start + MCI_RDR; + + /* Try to grab a DMA channel */ + host->dma.client.event_callback = atmci_dma_event; + dma_cap_set(DMA_SLAVE, host->dma.client.cap_mask); + host->dma.client.slave = slave; + + dma_async_client_register(&host->dma.client); + dma_async_client_chan_request(&host->dma.client); + } else { + dev_notice(&pdev->dev, "DMA not available, using PIO\n"); + } +#endif /* CONFIG_MMC_ATMELMCI_DMA */ + platform_set_drvdata(pdev, host); /* We need at least one slot to succeed */ @@ -1462,6 +1695,10 @@ static int __init atmci_probe(struct platform_device *pdev) return 0; err_init_slot: +#ifdef CONFIG_MMC_ATMELMCI_DMA + if (pdata->dma_slave) + dma_async_client_unregister(&host->dma.client); +#endif free_irq(irq, host); err_request_irq: iounmap(host->regs); @@ -1490,6 +1727,11 @@ static int __exit atmci_remove(struct platform_device *pdev) mci_readl(host, SR); clk_disable(host->mck); +#ifdef CONFIG_MMC_ATMELMCI_DMA + if (host->dma.client.slave) + dma_async_client_unregister(&host->dma.client); +#endif + free_irq(platform_get_irq(pdev, 0), host); iounmap(host->regs); |