diff options
Diffstat (limited to 'drivers/spi/spi-pxa2xx-pxadma.c')
| -rw-r--r-- | drivers/spi/spi-pxa2xx-pxadma.c | 490 |
1 files changed, 490 insertions, 0 deletions
diff --git a/drivers/spi/spi-pxa2xx-pxadma.c b/drivers/spi/spi-pxa2xx-pxadma.c new file mode 100644 index 000000000000..2916efc7cfe5 --- /dev/null +++ b/drivers/spi/spi-pxa2xx-pxadma.c @@ -0,0 +1,490 @@ +/* + * PXA2xx SPI private DMA support. + * + * Copyright (C) 2005 Stephen Street / StreetFire Sound Labs + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, write to the Free Software + * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. + */ + +#include <linux/init.h> +#include <linux/delay.h> +#include <linux/device.h> +#include <linux/dma-mapping.h> +#include <linux/pxa2xx_ssp.h> +#include <linux/spi/spi.h> +#include <linux/spi/pxa2xx_spi.h> + +#include "spi-pxa2xx.h" + +#define DMA_INT_MASK (DCSR_ENDINTR | DCSR_STARTINTR | DCSR_BUSERR) +#define RESET_DMA_CHANNEL (DCSR_NODESC | DMA_INT_MASK) + +bool pxa2xx_spi_dma_is_possible(size_t len) +{ + /* 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. + */ + return len > 0 && len <= MAX_DMA_LEN; +} + +int pxa2xx_spi_map_dma_buffers(struct driver_data *drv_data) +{ + struct spi_message *msg = drv_data->cur_msg; + struct device *dev = &msg->spi->dev; + + if (!drv_data->cur_chip->enable_dma) + return 0; + + if (msg->is_dma_mapped) + return drv_data->rx_dma && drv_data->tx_dma; + + if (!IS_DMA_ALIGNED(drv_data->rx) || !IS_DMA_ALIGNED(drv_data->tx)) + return 0; + + /* Modify setup if rx buffer is null */ + if (drv_data->rx == NULL) { + *drv_data->null_dma_buf = 0; + drv_data->rx = drv_data->null_dma_buf; + drv_data->rx_map_len = 4; + } else + drv_data->rx_map_len = drv_data->len; + + + /* Modify setup if tx buffer is null */ + if (drv_data->tx == NULL) { + *drv_data->null_dma_buf = 0; + drv_data->tx = drv_data->null_dma_buf; + drv_data->tx_map_len = 4; + } else + drv_data->tx_map_len = drv_data->len; + + /* Stream map the tx buffer. Always do DMA_TO_DEVICE first + * so we flush the cache *before* invalidating it, in case + * the tx and rx buffers overlap. + */ + drv_data->tx_dma = dma_map_single(dev, drv_data->tx, + drv_data->tx_map_len, DMA_TO_DEVICE); + if (dma_mapping_error(dev, drv_data->tx_dma)) + return 0; + + /* Stream map the rx buffer */ + drv_data->rx_dma = dma_map_single(dev, drv_data->rx, + drv_data->rx_map_len, DMA_FROM_DEVICE); + if (dma_mapping_error(dev, drv_data->rx_dma)) { + dma_unmap_single(dev, drv_data->tx_dma, + drv_data->tx_map_len, DMA_TO_DEVICE); + return 0; + } + + return 1; +} + +static void pxa2xx_spi_unmap_dma_buffers(struct driver_data *drv_data) +{ + struct device *dev; + + if (!drv_data->dma_mapped) + return; + + if (!drv_data->cur_msg->is_dma_mapped) { + dev = &drv_data->cur_msg->spi->dev; + dma_unmap_single(dev, drv_data->rx_dma, + drv_data->rx_map_len, DMA_FROM_DEVICE); + dma_unmap_single(dev, drv_data->tx_dma, + drv_data->tx_map_len, DMA_TO_DEVICE); + } + + drv_data->dma_mapped = 0; +} + +static int wait_ssp_rx_stall(void const __iomem *ioaddr) +{ + unsigned long limit = loops_per_jiffy << 1; + + while ((read_SSSR(ioaddr) & SSSR_BSY) && --limit) + cpu_relax(); + + return limit; +} + +static int wait_dma_channel_stop(int channel) +{ + unsigned long limit = loops_per_jiffy << 1; + + while (!(DCSR(channel) & DCSR_STOPSTATE) && --limit) + cpu_relax(); + + return limit; +} + +static void pxa2xx_spi_dma_error_stop(struct driver_data *drv_data, + const char *msg) +{ + void __iomem *reg = drv_data->ioaddr; + + /* Stop and reset */ + DCSR(drv_data->rx_channel) = RESET_DMA_CHANNEL; + DCSR(drv_data->tx_channel) = RESET_DMA_CHANNEL; + write_SSSR_CS(drv_data, drv_data->clear_sr); + write_SSCR1(read_SSCR1(reg) & ~drv_data->dma_cr1, reg); + if (!pxa25x_ssp_comp(drv_data)) + write_SSTO(0, reg); + pxa2xx_spi_flush(drv_data); + write_SSCR0(read_SSCR0(reg) & ~SSCR0_SSE, reg); + + pxa2xx_spi_unmap_dma_buffers(drv_data); + + dev_err(&drv_data->pdev->dev, "%s\n", msg); + + drv_data->cur_msg->state = ERROR_STATE; + tasklet_schedule(&drv_data->pump_transfers); +} + +static void pxa2xx_spi_dma_transfer_complete(struct driver_data *drv_data) +{ + void __iomem *reg = drv_data->ioaddr; + struct spi_message *msg = drv_data->cur_msg; + + /* Clear and disable interrupts on SSP and DMA channels*/ + write_SSCR1(read_SSCR1(reg) & ~drv_data->dma_cr1, reg); + write_SSSR_CS(drv_data, drv_data->clear_sr); + DCSR(drv_data->tx_channel) = RESET_DMA_CHANNEL; + DCSR(drv_data->rx_channel) = RESET_DMA_CHANNEL; + + if (wait_dma_channel_stop(drv_data->rx_channel) == 0) + dev_err(&drv_data->pdev->dev, + "dma_handler: dma rx channel stop failed\n"); + + if (wait_ssp_rx_stall(drv_data->ioaddr) == 0) + dev_err(&drv_data->pdev->dev, + "dma_transfer: ssp rx stall failed\n"); + + pxa2xx_spi_unmap_dma_buffers(drv_data); + + /* update the buffer pointer for the amount completed in dma */ + drv_data->rx += drv_data->len - + (DCMD(drv_data->rx_channel) & DCMD_LENGTH); + + /* read trailing data from fifo, it does not matter how many + * bytes are in the fifo just read until buffer is full + * or fifo is empty, which ever occurs first */ + drv_data->read(drv_data); + + /* return count of what was actually read */ + msg->actual_length += drv_data->len - + (drv_data->rx_end - drv_data->rx); + + /* Transfer delays and chip select release are + * handled in pump_transfers or giveback + */ + + /* Move to next transfer */ + msg->state = pxa2xx_spi_next_transfer(drv_data); + + /* Schedule transfer tasklet */ + tasklet_schedule(&drv_data->pump_transfers); +} + +void pxa2xx_spi_dma_handler(int channel, void *data) +{ + struct driver_data *drv_data = data; + u32 irq_status = DCSR(channel) & DMA_INT_MASK; + + if (irq_status & DCSR_BUSERR) { + + if (channel == drv_data->tx_channel) + pxa2xx_spi_dma_error_stop(drv_data, + "dma_handler: bad bus address on tx channel"); + else + pxa2xx_spi_dma_error_stop(drv_data, + "dma_handler: bad bus address on rx channel"); + return; + } + + /* PXA255x_SSP has no timeout interrupt, wait for tailing bytes */ + if ((channel == drv_data->tx_channel) + && (irq_status & DCSR_ENDINTR) + && (drv_data->ssp_type == PXA25x_SSP)) { + + /* Wait for rx to stall */ + if (wait_ssp_rx_stall(drv_data->ioaddr) == 0) + dev_err(&drv_data->pdev->dev, + "dma_handler: ssp rx stall failed\n"); + + /* finish this transfer, start the next */ + pxa2xx_spi_dma_transfer_complete(drv_data); + } +} + +irqreturn_t pxa2xx_spi_dma_transfer(struct driver_data *drv_data) +{ + u32 irq_status; + void __iomem *reg = drv_data->ioaddr; + + irq_status = read_SSSR(reg) & drv_data->mask_sr; + if (irq_status & SSSR_ROR) { + pxa2xx_spi_dma_error_stop(drv_data, + "dma_transfer: fifo overrun"); + return IRQ_HANDLED; + } + + /* Check for false positive timeout */ + if ((irq_status & SSSR_TINT) + && (DCSR(drv_data->tx_channel) & DCSR_RUN)) { + write_SSSR(SSSR_TINT, reg); + return IRQ_HANDLED; + } + + if (irq_status & SSSR_TINT || drv_data->rx == drv_data->rx_end) { + + /* Clear and disable timeout interrupt, do the rest in + * dma_transfer_complete */ + if (!pxa25x_ssp_comp(drv_data)) + write_SSTO(0, reg); + + /* finish this transfer, start the next */ + pxa2xx_spi_dma_transfer_complete(drv_data); + + return IRQ_HANDLED; + } + + /* Opps problem detected */ + return IRQ_NONE; +} + +int pxa2xx_spi_dma_prepare(struct driver_data *drv_data, u32 dma_burst) +{ + u32 dma_width; + + switch (drv_data->n_bytes) { + case 1: + dma_width = DCMD_WIDTH1; + break; + case 2: + dma_width = DCMD_WIDTH2; + break; + default: + dma_width = DCMD_WIDTH4; + break; + } + + /* Setup rx DMA Channel */ + DCSR(drv_data->rx_channel) = RESET_DMA_CHANNEL; + DSADR(drv_data->rx_channel) = drv_data->ssdr_physical; + DTADR(drv_data->rx_channel) = drv_data->rx_dma; + if (drv_data->rx == drv_data->null_dma_buf) + /* No target address increment */ + DCMD(drv_data->rx_channel) = DCMD_FLOWSRC + | dma_width + | dma_burst + | drv_data->len; + else + DCMD(drv_data->rx_channel) = DCMD_INCTRGADDR + | DCMD_FLOWSRC + | dma_width + | dma_burst + | drv_data->len; + + /* Setup tx DMA Channel */ + DCSR(drv_data->tx_channel) = RESET_DMA_CHANNEL; + DSADR(drv_data->tx_channel) = drv_data->tx_dma; + DTADR(drv_data->tx_channel) = drv_data->ssdr_physical; + if (drv_data->tx == drv_data->null_dma_buf) + /* No source address increment */ + DCMD(drv_data->tx_channel) = DCMD_FLOWTRG + | dma_width + | dma_burst + | drv_data->len; + else + DCMD(drv_data->tx_channel) = DCMD_INCSRCADDR + | DCMD_FLOWTRG + | dma_width + | dma_burst + | drv_data->len; + + /* Enable dma end irqs on SSP to detect end of transfer */ + if (drv_data->ssp_type == PXA25x_SSP) + DCMD(drv_data->tx_channel) |= DCMD_ENDIRQEN; + + return 0; +} + +void pxa2xx_spi_dma_start(struct driver_data *drv_data) +{ + DCSR(drv_data->rx_channel) |= DCSR_RUN; + DCSR(drv_data->tx_channel) |= DCSR_RUN; +} + +int pxa2xx_spi_dma_setup(struct driver_data *drv_data) +{ + struct device *dev = &drv_data->pdev->dev; + struct ssp_device *ssp = drv_data->ssp; + + /* Get two DMA channels (rx and tx) */ + drv_data->rx_channel = pxa_request_dma("pxa2xx_spi_ssp_rx", + DMA_PRIO_HIGH, + pxa2xx_spi_dma_handler, + drv_data); + if (drv_data->rx_channel < 0) { + dev_err(dev, "problem (%d) requesting rx channel\n", + drv_data->rx_channel); + return -ENODEV; + } + drv_data->tx_channel = pxa_request_dma("pxa2xx_spi_ssp_tx", + DMA_PRIO_MEDIUM, + pxa2xx_spi_dma_handler, + drv_data); + if (drv_data->tx_channel < 0) { + dev_err(dev, "problem (%d) requesting tx channel\n", + drv_data->tx_channel); + pxa_free_dma(drv_data->rx_channel); + return -ENODEV; + } + + DRCMR(ssp->drcmr_rx) = DRCMR_MAPVLD | drv_data->rx_channel; + DRCMR(ssp->drcmr_tx) = DRCMR_MAPVLD | drv_data->tx_channel; + + return 0; +} + +void pxa2xx_spi_dma_release(struct driver_data *drv_data) +{ + struct ssp_device *ssp = drv_data->ssp; + + DRCMR(ssp->drcmr_rx) = 0; + DRCMR(ssp->drcmr_tx) = 0; + + if (drv_data->tx_channel != 0) + pxa_free_dma(drv_data->tx_channel); + if (drv_data->rx_channel != 0) + pxa_free_dma(drv_data->rx_channel); +} + +void pxa2xx_spi_dma_resume(struct driver_data *drv_data) +{ + if (drv_data->rx_channel != -1) + DRCMR(drv_data->ssp->drcmr_rx) = + DRCMR_MAPVLD | drv_data->rx_channel; + if (drv_data->tx_channel != -1) + DRCMR(drv_data->ssp->drcmr_tx) = + DRCMR_MAPVLD | drv_data->tx_channel; +} + +int pxa2xx_spi_set_dma_burst_and_threshold(struct chip_data *chip, + struct spi_device *spi, + u8 bits_per_word, u32 *burst_code, + u32 *threshold) +{ + struct pxa2xx_spi_chip *chip_info = + (struct pxa2xx_spi_chip *)spi->controller_data; + int bytes_per_word; + int burst_bytes; + int thresh_words; + int req_burst_size; + int retval = 0; + + /* Set the threshold (in registers) to equal the same amount of data + * as represented by burst size (in bytes). The computation below + * is (burst_size rounded up to nearest 8 byte, word or long word) + * divided by (bytes/register); the tx threshold is the inverse of + * the rx, so that there will always be enough data in the rx fifo + * to satisfy a burst, and there will always be enough space in the + * tx fifo to accept a burst (a tx burst will overwrite the fifo if + * there is not enough space), there must always remain enough empty + * space in the rx fifo for any data loaded to the tx fifo. + * Whenever burst_size (in bytes) equals bits/word, the fifo threshold + * will be 8, or half the fifo; + * The threshold can only be set to 2, 4 or 8, but not 16, because + * to burst 16 to the tx fifo, the fifo would have to be empty; + * however, the minimum fifo trigger level is 1, and the tx will + * request service when the fifo is at this level, with only 15 spaces. + */ + + /* find bytes/word */ + if (bits_per_word <= 8) + bytes_per_word = 1; + else if (bits_per_word <= 16) + bytes_per_word = 2; + else + bytes_per_word = 4; + + /* use struct pxa2xx_spi_chip->dma_burst_size if available */ + if (chip_info) + req_burst_size = chip_info->dma_burst_size; + else { + switch (chip->dma_burst_size) { + default: + /* if the default burst size is not set, + * do it now */ + chip->dma_burst_size = DCMD_BURST8; + case DCMD_BURST8: + req_burst_size = 8; + break; + case DCMD_BURST16: + req_burst_size = 16; + break; + case DCMD_BURST32: + req_burst_size = 32; + break; + } + } + if (req_burst_size <= 8) { + *burst_code = DCMD_BURST8; + burst_bytes = 8; + } else if (req_burst_size <= 16) { + if (bytes_per_word == 1) { + /* don't burst more than 1/2 the fifo */ + *burst_code = DCMD_BURST8; + burst_bytes = 8; + retval = 1; + } else { + *burst_code = DCMD_BURST16; + burst_bytes = 16; + } + } else { + if (bytes_per_word == 1) { + /* don't burst more than 1/2 the fifo */ + *burst_code = DCMD_BURST8; + burst_bytes = 8; + retval = 1; + } else if (bytes_per_word == 2) { + /* don't burst more than 1/2 the fifo */ + *burst_code = DCMD_BURST16; + burst_bytes = 16; + retval = 1; + } else { + *burst_code = DCMD_BURST32; + burst_bytes = 32; + } + } + + thresh_words = burst_bytes / bytes_per_word; + + /* thresh_words will be between 2 and 8 */ + *threshold = (SSCR1_RxTresh(thresh_words) & SSCR1_RFT) + | (SSCR1_TxTresh(16-thresh_words) & SSCR1_TFT); + + return retval; +} |