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path: root/drivers/spi/spi-pxa2xx-pxadma.c
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-rw-r--r--drivers/spi/spi-pxa2xx-pxadma.c490
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 00000000000..2916efc7cfe
--- /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;
+}