diff options
Diffstat (limited to 'drivers/spi/pxa2xx_spi.c')
| -rw-r--r-- | drivers/spi/pxa2xx_spi.c | 116 |
1 files changed, 91 insertions, 25 deletions
diff --git a/drivers/spi/pxa2xx_spi.c b/drivers/spi/pxa2xx_spi.c index 34c7c987568..d47d3636227 100644 --- a/drivers/spi/pxa2xx_spi.c +++ b/drivers/spi/pxa2xx_spi.c @@ -47,9 +47,10 @@ MODULE_ALIAS("platform:pxa2xx-spi"); #define MAX_BUSES 3 -#define DMA_INT_MASK (DCSR_ENDINTR | DCSR_STARTINTR | DCSR_BUSERR) -#define RESET_DMA_CHANNEL (DCSR_NODESC | DMA_INT_MASK) -#define IS_DMA_ALIGNED(x) (((u32)(x)&0x07)==0) +#define DMA_INT_MASK (DCSR_ENDINTR | DCSR_STARTINTR | DCSR_BUSERR) +#define RESET_DMA_CHANNEL (DCSR_NODESC | DMA_INT_MASK) +#define IS_DMA_ALIGNED(x) ((((u32)(x)) & 0x07) == 0) +#define MAX_DMA_LEN 8191 /* * for testing SSCR1 changes that require SSP restart, basically @@ -144,7 +145,6 @@ struct driver_data { size_t tx_map_len; u8 n_bytes; u32 dma_width; - int cs_change; int (*write)(struct driver_data *drv_data); int (*read)(struct driver_data *drv_data); irqreturn_t (*transfer_handler)(struct driver_data *drv_data); @@ -406,8 +406,45 @@ static void giveback(struct driver_data *drv_data) struct spi_transfer, transfer_list); + /* Delay if requested before any change in chip select */ + if (last_transfer->delay_usecs) + udelay(last_transfer->delay_usecs); + + /* Drop chip select UNLESS cs_change is true or we are returning + * a message with an error, or next message is for another chip + */ if (!last_transfer->cs_change) drv_data->cs_control(PXA2XX_CS_DEASSERT); + else { + struct spi_message *next_msg; + + /* Holding of cs was hinted, but we need to make sure + * the next message is for the same chip. Don't waste + * time with the following tests unless this was hinted. + * + * We cannot postpone this until pump_messages, because + * after calling msg->complete (below) the driver that + * sent the current message could be unloaded, which + * could invalidate the cs_control() callback... + */ + + /* get a pointer to the next message, if any */ + spin_lock_irqsave(&drv_data->lock, flags); + if (list_empty(&drv_data->queue)) + next_msg = NULL; + else + next_msg = list_entry(drv_data->queue.next, + struct spi_message, queue); + spin_unlock_irqrestore(&drv_data->lock, flags); + + /* see if the next and current messages point + * to the same chip + */ + if (next_msg && next_msg->spi != msg->spi) + next_msg = NULL; + if (!next_msg || msg->state == ERROR_STATE) + drv_data->cs_control(PXA2XX_CS_DEASSERT); + } msg->state = NULL; if (msg->complete) @@ -490,10 +527,9 @@ static void dma_transfer_complete(struct driver_data *drv_data) msg->actual_length += drv_data->len - (drv_data->rx_end - drv_data->rx); - /* Release chip select if requested, transfer delays are - * handled in pump_transfers */ - if (drv_data->cs_change) - drv_data->cs_control(PXA2XX_CS_DEASSERT); + /* Transfer delays and chip select release are + * handled in pump_transfers or giveback + */ /* Move to next transfer */ msg->state = next_transfer(drv_data); @@ -602,10 +638,9 @@ static void int_transfer_complete(struct driver_data *drv_data) drv_data->cur_msg->actual_length += drv_data->len - (drv_data->rx_end - drv_data->rx); - /* Release chip select if requested, transfer delays are - * handled in pump_transfers */ - if (drv_data->cs_change) - drv_data->cs_control(PXA2XX_CS_DEASSERT); + /* Transfer delays and chip select release are + * handled in pump_transfers or giveback + */ /* Move to next transfer */ drv_data->cur_msg->state = next_transfer(drv_data); @@ -840,23 +875,40 @@ static void pump_transfers(unsigned long data) return; } - /* Delay if requested at end of transfer*/ + /* Delay if requested at end of transfer before CS change */ if (message->state == RUNNING_STATE) { previous = list_entry(transfer->transfer_list.prev, struct spi_transfer, transfer_list); if (previous->delay_usecs) udelay(previous->delay_usecs); + + /* Drop chip select only if cs_change is requested */ + if (previous->cs_change) + drv_data->cs_control(PXA2XX_CS_DEASSERT); } - /* Check transfer length */ - if (transfer->len > 8191) - { - dev_warn(&drv_data->pdev->dev, "pump_transfers: transfer " - "length greater than 8191\n"); - message->status = -EINVAL; - giveback(drv_data); - return; + /* Check for transfers that need multiple DMA segments */ + if (transfer->len > MAX_DMA_LEN && chip->enable_dma) { + + /* reject already-mapped transfers; PIO won't always work */ + if (message->is_dma_mapped + || transfer->rx_dma || transfer->tx_dma) { + dev_err(&drv_data->pdev->dev, + "pump_transfers: mapped transfer length " + "of %u is greater than %d\n", + transfer->len, MAX_DMA_LEN); + message->status = -EINVAL; + giveback(drv_data); + return; + } + + /* warn ... we force this to PIO mode */ + if (printk_ratelimit()) + dev_warn(&message->spi->dev, "pump_transfers: " + "DMA disabled for transfer length %ld " + "greater than %d\n", + (long)drv_data->len, MAX_DMA_LEN); } /* Setup the transfer state based on the type of transfer */ @@ -878,7 +930,6 @@ static void pump_transfers(unsigned long data) drv_data->len = transfer->len & DCMD_LENGTH; drv_data->write = drv_data->tx ? chip->write : null_writer; drv_data->read = drv_data->rx ? chip->read : null_reader; - drv_data->cs_change = transfer->cs_change; /* Change speed and bit per word on a per transfer */ cr0 = chip->cr0; @@ -925,7 +976,7 @@ static void pump_transfers(unsigned long data) &dma_thresh)) if (printk_ratelimit()) dev_warn(&message->spi->dev, - "pump_transfer: " + "pump_transfers: " "DMA burst size reduced to " "match bits_per_word\n"); } @@ -939,8 +990,23 @@ static void pump_transfers(unsigned long data) message->state = RUNNING_STATE; - /* Try to map dma buffer and do a dma transfer if successful */ - if ((drv_data->dma_mapped = map_dma_buffers(drv_data))) { + /* Try to map dma buffer and do a dma transfer if successful, but + * only if the length is non-zero and less than MAX_DMA_LEN. + * + * Zero-length non-descriptor DMA is illegal on PXA2xx; force use + * of PIO instead. Care is needed above because the transfer may + * have have been passed with buffers that are already dma mapped. + * A zero-length transfer in PIO mode will not try to write/read + * to/from the buffers + * + * REVISIT large transfers are exactly where we most want to be + * using DMA. If this happens much, split those transfers into + * multiple DMA segments rather than forcing PIO. + */ + drv_data->dma_mapped = 0; + if (drv_data->len > 0 && drv_data->len <= MAX_DMA_LEN) + drv_data->dma_mapped = map_dma_buffers(drv_data); + if (drv_data->dma_mapped) { /* Ensure we have the correct interrupt handler */ drv_data->transfer_handler = dma_transfer; |