diff options
Diffstat (limited to 'drivers')
| -rw-r--r-- | drivers/spi/mxs_spi.c | 117 |
1 files changed, 116 insertions, 1 deletions
diff --git a/drivers/spi/mxs_spi.c b/drivers/spi/mxs_spi.c index 1733203..4ff8474 100644 --- a/drivers/spi/mxs_spi.c +++ b/drivers/spi/mxs_spi.c @@ -31,17 +31,32 @@ #include <asm/arch/clock.h> #include <asm/arch/imx-regs.h> #include <asm/arch/sys_proto.h> +#include <asm/arch/dma.h> #define MXS_SPI_MAX_TIMEOUT 1000000 #define MXS_SPI_PORT_OFFSET 0x2000 #define MXS_SSP_CHIPSELECT_MASK 0x00300000 #define MXS_SSP_CHIPSELECT_SHIFT 20 +#define MXSSSP_SMALL_TRANSFER 512 + +/* + * CONFIG_MXS_SPI_DMA_ENABLE: Experimental mixed PIO/DMA support for MXS SPI + * host. Use with utmost caution! + * + * Enabling this is not yet recommended since this + * still doesn't support transfers to/from unaligned + * addresses. Therefore this driver will not work + * for example with saving environment. This is + * caused by DMA alignment constraints on MXS. + */ + struct mxs_spi_slave { struct spi_slave slave; uint32_t max_khz; uint32_t mode; struct mx28_ssp_regs *regs; + struct mxs_dma_desc *desc; }; static inline struct mxs_spi_slave *to_mxs_slave(struct spi_slave *slave) @@ -69,6 +84,7 @@ struct spi_slave *spi_setup_slave(unsigned int bus, unsigned int cs, uint32_t addr; struct mx28_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); @@ -79,6 +95,13 @@ 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; + addr = MXS_SSP0_BASE + (bus * MXS_SPI_PORT_OFFSET); mxs_slave->slave.bus = bus; @@ -86,6 +109,7 @@ 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 mx28_ssp_regs *)addr; + mxs_slave->desc = desc; ssp_regs = mxs_slave->regs; reg = readl(&ssp_regs->hw_ssp_ctrl0); @@ -94,11 +118,18 @@ struct spi_slave *spi_setup_slave(unsigned int bus, unsigned int cs, writel(reg, &ssp_regs->hw_ssp_ctrl0); return &mxs_slave->slave; + +err_init: + mxs_dma_desc_free(desc); +err_desc: + free(mxs_slave); + return NULL; } 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); } @@ -195,15 +226,81 @@ 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; + struct mx28_ssp_regs *ssp_regs = slave->regs; + uint32_t ctrl0 = SSP_CTRL0_DATA_XFER; + uint32_t cache_data_count; + int dmach; + + memset(desc, 0, sizeof(struct mxs_dma_desc)); + desc->address = (dma_addr_t)desc; + + 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; + + writel(length, &ssp_regs->hw_ssp_xfer_size); + + if (length % ARCH_DMA_MINALIGN) + cache_data_count = roundup(length, ARCH_DMA_MINALIGN); + 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; + + /* 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; + + slave->desc->cmd.pio_words[0] = ctrl0; + + dmach = MXS_DMA_CHANNEL_AHB_APBH_SSP0 + slave->slave.bus; + mxs_dma_desc_append(dmach, slave->desc); + if (mxs_dma_go(dmach)) + return -EINVAL; + + /* The data arrived into DRAM, invalidate cache over them */ + if (!write) { + invalidate_dcache_range((uint32_t)data, + (uint32_t)(data + cache_data_count)); + } + + return 0; +} + int spi_xfer(struct spi_slave *slave, unsigned int bitlen, const void *dout, void *din, unsigned long flags) { struct mxs_spi_slave *mxs_slave = to_mxs_slave(slave); + struct mx28_ssp_regs *ssp_regs = mxs_slave->regs; int len = bitlen / 8; char dummy; int write = 0; char *data = NULL; +#ifdef CONFIG_MXS_SPI_DMA_ENABLE + int dma = 1; +#else + int dma = 0; +#endif + if (bitlen == 0) { if (flags & SPI_XFER_END) { din = (void *)&dummy; @@ -227,5 +324,23 @@ int spi_xfer(struct spi_slave *slave, unsigned int bitlen, write = 0; } - return mxs_spi_xfer_pio(mxs_slave, data, len, write, flags); + /* + * Check for alignment, if the buffer is aligned, do DMA transfer, + * PIO otherwise. This is a temporary workaround until proper bounce + * buffer is in place. + */ + if (dma) { + if (((uint32_t)data) & (ARCH_DMA_MINALIGN - 1)) + dma = 0; + if (((uint32_t)len) & (ARCH_DMA_MINALIGN - 1)) + dma = 0; + } + + if (!dma || (len < MXSSSP_SMALL_TRANSFER)) { + writel(SSP_CTRL1_DMA_ENABLE, &ssp_regs->hw_ssp_ctrl1_clr); + return mxs_spi_xfer_pio(mxs_slave, data, len, write, flags); + } else { + writel(SSP_CTRL1_DMA_ENABLE, &ssp_regs->hw_ssp_ctrl1_set); + return mxs_spi_xfer_dma(mxs_slave, data, len, write, flags); + } } |