diff options
Diffstat (limited to 'drivers')
| -rw-r--r-- | drivers/spi/mxs_spi.c | 96 |
1 files changed, 65 insertions, 31 deletions
diff --git a/drivers/spi/mxs_spi.c b/drivers/spi/mxs_spi.c index 5fa7f2b..168dbe4 100644 --- a/drivers/spi/mxs_spi.c +++ b/drivers/spi/mxs_spi.c @@ -56,7 +56,6 @@ struct mxs_spi_slave { uint32_t max_khz; uint32_t mode; struct mxs_ssp_regs *regs; - struct mxs_dma_desc *desc; }; static inline struct mxs_spi_slave *to_mxs_slave(struct spi_slave *slave) @@ -84,7 +83,6 @@ struct spi_slave *spi_setup_slave(unsigned int bus, unsigned int cs, uint32_t addr; struct mxs_ssp_regs *ssp_regs; int reg; - struct mxs_dma_desc *desc; if (!spi_cs_is_valid(bus, cs)) { printf("mxs_spi: invalid bus %d / chip select %d\n", bus, cs); @@ -95,10 +93,6 @@ struct spi_slave *spi_setup_slave(unsigned int bus, unsigned int cs, if (!mxs_slave) return NULL; - desc = mxs_dma_desc_alloc(); - if (!desc) - goto err_desc; - if (mxs_dma_init_channel(bus)) goto err_init; @@ -109,7 +103,6 @@ struct spi_slave *spi_setup_slave(unsigned int bus, unsigned int cs, mxs_slave->max_khz = max_hz / 1000; mxs_slave->mode = mode; mxs_slave->regs = (struct mxs_ssp_regs *)addr; - mxs_slave->desc = desc; ssp_regs = mxs_slave->regs; reg = readl(&ssp_regs->hw_ssp_ctrl0); @@ -120,8 +113,6 @@ struct spi_slave *spi_setup_slave(unsigned int bus, unsigned int cs, return &mxs_slave->slave; err_init: - mxs_dma_desc_free(desc); -err_desc: free(mxs_slave); return NULL; } @@ -129,7 +120,6 @@ err_desc: void spi_free_slave(struct spi_slave *slave) { struct mxs_spi_slave *mxs_slave = to_mxs_slave(slave); - mxs_dma_desc_free(mxs_slave->desc); free(mxs_slave); } @@ -228,19 +218,24 @@ static int mxs_spi_xfer_pio(struct mxs_spi_slave *slave, static int mxs_spi_xfer_dma(struct mxs_spi_slave *slave, char *data, int length, int write, unsigned long flags) { - struct mxs_dma_desc *desc = slave->desc; + const int xfer_max_sz = 0xff00; + const int desc_count = DIV_ROUND_UP(length, xfer_max_sz) + 1; struct mxs_ssp_regs *ssp_regs = slave->regs; - uint32_t ctrl0 = SSP_CTRL0_DATA_XFER; + struct mxs_dma_desc *dp; + uint32_t ctrl0; uint32_t cache_data_count; int dmach; + int tl; + + ALLOC_CACHE_ALIGN_BUFFER(struct mxs_dma_desc, desc, desc_count); + + memset(desc, 0, sizeof(struct mxs_dma_desc) * desc_count); - memset(desc, 0, sizeof(struct mxs_dma_desc)); - desc->address = (dma_addr_t)desc; + ctrl0 = readl(&ssp_regs->hw_ssp_ctrl0); + ctrl0 |= SSP_CTRL0_DATA_XFER; if (flags & SPI_XFER_BEGIN) ctrl0 |= SSP_CTRL0_LOCK_CS; - if (flags & SPI_XFER_END) - ctrl0 |= SSP_CTRL0_IGNORE_CRC; if (!write) ctrl0 |= SSP_CTRL0_READ; @@ -251,27 +246,66 @@ static int mxs_spi_xfer_dma(struct mxs_spi_slave *slave, else cache_data_count = length; - if (!write) { - slave->desc->cmd.data = MXS_DMA_DESC_COMMAND_DMA_WRITE; - slave->desc->cmd.address = (dma_addr_t)data; - } else { - slave->desc->cmd.data = MXS_DMA_DESC_COMMAND_DMA_READ; - slave->desc->cmd.address = (dma_addr_t)data; - + if (write) /* Flush data to DRAM so DMA can pick them up */ flush_dcache_range((uint32_t)data, (uint32_t)(data + cache_data_count)); - } - slave->desc->cmd.data |= MXS_DMA_DESC_IRQ | MXS_DMA_DESC_DEC_SEM | - (length << MXS_DMA_DESC_BYTES_OFFSET) | - (1 << MXS_DMA_DESC_PIO_WORDS_OFFSET) | - MXS_DMA_DESC_WAIT4END; + dmach = MXS_DMA_CHANNEL_AHB_APBH_SSP0 + slave->slave.bus; - slave->desc->cmd.pio_words[0] = ctrl0; + dp = desc; + while (length) { + dp->address = (dma_addr_t)dp; + dp->cmd.address = (dma_addr_t)data; + + /* + * This is correct, even though it does indeed look insane. + * I hereby have to, wholeheartedly, thank Freescale Inc., + * for always inventing insane hardware and keeping me busy + * and employed ;-) + */ + if (write) + dp->cmd.data = MXS_DMA_DESC_COMMAND_DMA_READ; + else + dp->cmd.data = MXS_DMA_DESC_COMMAND_DMA_WRITE; + + /* + * The DMA controller can transfer large chunks (64kB) at + * time by setting the transfer length to 0. Setting tl to + * 0x10000 will overflow below and make .data contain 0. + * Otherwise, 0xff00 is the transfer maximum. + */ + if (length >= 0x10000) + tl = 0x10000; + else + tl = min(length, xfer_max_sz); + + dp->cmd.data |= + (tl << MXS_DMA_DESC_BYTES_OFFSET) | + (1 << MXS_DMA_DESC_PIO_WORDS_OFFSET) | + MXS_DMA_DESC_HALT_ON_TERMINATE | + MXS_DMA_DESC_TERMINATE_FLUSH; + dp->cmd.pio_words[0] = ctrl0; + + data += tl; + length -= tl; + + mxs_dma_desc_append(dmach, dp); + + dp++; + } + + dp->address = (dma_addr_t)dp; + dp->cmd.address = (dma_addr_t)0; + dp->cmd.data = MXS_DMA_DESC_COMMAND_NO_DMAXFER | + (1 << MXS_DMA_DESC_PIO_WORDS_OFFSET) | + MXS_DMA_DESC_IRQ | MXS_DMA_DESC_DEC_SEM; + if (flags & SPI_XFER_END) { + ctrl0 &= ~SSP_CTRL0_LOCK_CS; + dp->cmd.pio_words[0] = ctrl0 | SSP_CTRL0_IGNORE_CRC; + } + mxs_dma_desc_append(dmach, dp); - dmach = MXS_DMA_CHANNEL_AHB_APBH_SSP0 + slave->slave.bus; - mxs_dma_desc_append(dmach, slave->desc); if (mxs_dma_go(dmach)) return -EINVAL; |