SPI read errors are reported even with the board sitting idle.
Fixes have been posted to linux-spi mailing list but not merged yet, so
we'll just pull the patches and apply them locally:

*001-spi-qup-Add-DMA-capabilities.patch is pulled from:
 http://marc.info/?l=linux-spi&m=140381685115859&w=2

*002-v3-spi-qup-Fix-incorrect-block-transfers.patch is pulled from:
 http://marc.info/?l=linux-spi&m=141211211011539&w=2

Signed-off-by: Mathieu Olivari <[email protected]>
---
 .../patches/001-spi-qup-Add-DMA-capabilities.patch | 522 +++++++++++++++++++++
 ...-v3-spi-qup-Fix-incorrect-block-transfers.patch | 376 +++++++++++++++
 2 files changed, 898 insertions(+)
 create mode 100644 
target/linux/ipq806x/patches/001-spi-qup-Add-DMA-capabilities.patch
 create mode 100644 
target/linux/ipq806x/patches/002-v3-spi-qup-Fix-incorrect-block-transfers.patch

diff --git 
a/target/linux/ipq806x/patches/001-spi-qup-Add-DMA-capabilities.patch 
b/target/linux/ipq806x/patches/001-spi-qup-Add-DMA-capabilities.patch
new file mode 100644
index 0000000..62badd5
--- /dev/null
+++ b/target/linux/ipq806x/patches/001-spi-qup-Add-DMA-capabilities.patch
@@ -0,0 +1,522 @@
+Content-Type: text/plain; charset="utf-8"
+MIME-Version: 1.0
+Content-Transfer-Encoding: 7bit
+Subject: spi: qup: Add DMA capabilities
+From: Andy Gross <[email protected]>
+X-Patchwork-Id: 4432401
+Message-Id: <[email protected]>
+To: Mark Brown <[email protected]>
+Cc: [email protected], Sagar Dharia <[email protected]>,
+       Daniel Sneddon <[email protected]>,
+       Bjorn Andersson <[email protected]>,
+       "Ivan T. Ivanov" <[email protected]>,
+       [email protected], [email protected],
+       [email protected], Andy Gross <[email protected]>
+Date: Thu, 26 Jun 2014 16:06:21 -0500
+
+This patch adds DMA capabilities to the spi-qup driver.  If DMA channels are
+present, the QUP will use DMA instead of block mode for transfers to/from SPI
+peripherals for transactions larger than the length of a block.
+
+Signed-off-by: Andy Gross <[email protected]>
+
+---
+.../devicetree/bindings/spi/qcom,spi-qup.txt       |   10 +
+ drivers/spi/spi-qup.c                              |  361 ++++++++++++++++++--
+ 2 files changed, 350 insertions(+), 21 deletions(-)
+
+--- a/Documentation/devicetree/bindings/spi/qcom,spi-qup.txt
++++ b/Documentation/devicetree/bindings/spi/qcom,spi-qup.txt
+@@ -27,6 +27,11 @@ Optional properties:
+ - spi-max-frequency: Specifies maximum SPI clock frequency,
+                      Units - Hz. Definition as per
+                      Documentation/devicetree/bindings/spi/spi-bus.txt
++- dmas :             Two DMA channel specifiers following the convention 
outlined
++                     in bindings/dma/dma.txt
++- dma-names:         Names for the dma channels, if present. There must be at
++                     least one channel named "tx" for transmit and named "rx" 
for
++                     receive.
+ - num-cs:     total number of chipselects
+ - cs-gpios:   should specify GPIOs used for chipselects.
+               The gpios will be referred to as reg = <index> in the SPI child
+@@ -51,6 +56,10 @@ Example:
+               clocks = <&gcc GCC_BLSP2_QUP2_SPI_APPS_CLK>, <&gcc 
GCC_BLSP2_AHB_CLK>;
+               clock-names = "core", "iface";
+ 
++              dmas = <&blsp2_bam 2>,
++                      <&blsp2_bam 3>;
++              dma-names = "rx", "tx";
++
+               pinctrl-names = "default";
+               pinctrl-0 = <&spi8_default>;
+ 
+--- a/drivers/spi/spi-qup.c
++++ b/drivers/spi/spi-qup.c
+@@ -22,6 +22,8 @@
+ #include <linux/platform_device.h>
+ #include <linux/pm_runtime.h>
+ #include <linux/spi/spi.h>
++#include <linux/dmaengine.h>
++#include <linux/dma-mapping.h>
+ 
+ #define QUP_CONFIG                    0x0000
+ #define QUP_STATE                     0x0004
+@@ -116,6 +118,8 @@
+ 
+ #define SPI_NUM_CHIPSELECTS           4
+ 
++#define SPI_MAX_XFER                  (SZ_64K - 64)
++
+ /* high speed mode is when bus rate is greater then 26MHz */
+ #define SPI_HS_MIN_RATE                       26000000
+ #define SPI_MAX_RATE                  50000000
+@@ -143,6 +147,17 @@ struct spi_qup {
+       int                     tx_bytes;
+       int                     rx_bytes;
+       int                     qup_v1;
++
++      int                     use_dma;
++
++      struct dma_chan         *rx_chan;
++      struct dma_slave_config rx_conf;
++      struct dma_chan         *tx_chan;
++      struct dma_slave_config tx_conf;
++      dma_addr_t              rx_dma;
++      dma_addr_t              tx_dma;
++      void                    *dummy;
++      atomic_t                dma_outstanding;
+ };
+ 
+ 
+@@ -266,6 +281,221 @@ static void spi_qup_fifo_write(struct sp
+       }
+ }
+ 
++static void qup_dma_callback(void *data)
++{
++      struct spi_qup *controller = data;
++
++      if (atomic_dec_and_test(&controller->dma_outstanding))
++              complete(&controller->done);
++}
++
++static int spi_qup_do_dma(struct spi_qup *controller, struct spi_transfer 
*xfer)
++{
++      struct dma_async_tx_descriptor *rxd, *txd;
++      dma_cookie_t rx_cookie, tx_cookie;
++      u32 xfer_len, rx_align = 0, tx_align = 0, n_words;
++      struct scatterlist tx_sg[2], rx_sg[2];
++      int ret = 0;
++      u32 bytes_to_xfer = xfer->len;
++      u32 offset = 0;
++      u32 rx_nents = 0, tx_nents = 0;
++      dma_addr_t rx_dma = 0, tx_dma = 0, rx_dummy_dma = 0, tx_dummy_dma = 0;
++
++
++      if (xfer->rx_buf) {
++              rx_dma = dma_map_single(controller->dev, xfer->rx_buf,
++                      xfer->len, DMA_FROM_DEVICE);
++
++              if (dma_mapping_error(controller->dev, rx_dma)) {
++                      ret = -ENOMEM;
++                      return ret;
++              }
++
++              /* check to see if we need dummy buffer for leftover bytes */
++              rx_align = xfer->len % controller->in_blk_sz;
++              if (rx_align) {
++                      rx_dummy_dma = dma_map_single(controller->dev,
++                              controller->dummy, controller->in_fifo_sz,
++                              DMA_FROM_DEVICE);
++
++                      if (dma_mapping_error(controller->dev, rx_dummy_dma)) {
++                              ret = -ENOMEM;
++                              goto err_map_rx_dummy;
++                      }
++              }
++      }
++
++      if (xfer->tx_buf) {
++              tx_dma = dma_map_single(controller->dev,
++                      (void *)xfer->tx_buf, xfer->len, DMA_TO_DEVICE);
++
++              if (dma_mapping_error(controller->dev, tx_dma)) {
++                      ret = -ENOMEM;
++                      goto err_map_tx;
++              }
++
++              /* check to see if we need dummy buffer for leftover bytes */
++              tx_align = xfer->len % controller->out_blk_sz;
++              if (tx_align) {
++                      memcpy(controller->dummy + SZ_1K,
++                              xfer->tx_buf + xfer->len - tx_align,
++                              tx_align);
++                      memset(controller->dummy + SZ_1K + tx_align, 0,
++                              controller->out_blk_sz - tx_align);
++
++                      tx_dummy_dma = dma_map_single(controller->dev,
++                              controller->dummy + SZ_1K,
++                              controller->out_blk_sz, DMA_TO_DEVICE);
++
++                      if (dma_mapping_error(controller->dev, tx_dummy_dma)) {
++                              ret = -ENOMEM;
++                              goto err_map_tx_dummy;
++                      }
++              }
++      }
++
++      atomic_set(&controller->dma_outstanding, 0);
++
++      while (bytes_to_xfer > 0) {
++              xfer_len = min_t(u32, bytes_to_xfer, SPI_MAX_XFER);
++              n_words = DIV_ROUND_UP(xfer_len, controller->w_size);
++
++              /* write out current word count to controller */
++              writel_relaxed(n_words, controller->base + QUP_MX_INPUT_CNT);
++              writel_relaxed(n_words, controller->base + QUP_MX_OUTPUT_CNT);
++
++              reinit_completion(&controller->done);
++
++              if (xfer->tx_buf) {
++                      /* recalc align for each transaction */
++                      tx_align = xfer_len % controller->out_blk_sz;
++
++                      if (tx_align)
++                              tx_nents = 2;
++                      else
++                              tx_nents = 1;
++
++                      /* initialize scatterlists */
++                      sg_init_table(tx_sg, tx_nents);
++                      sg_dma_len(&tx_sg[0]) = xfer_len - tx_align;
++                      sg_dma_address(&tx_sg[0]) = tx_dma + offset;
++
++                      /* account for non block size transfer */
++                      if (tx_align) {
++                              sg_dma_len(&tx_sg[1]) = controller->out_blk_sz;
++                              sg_dma_address(&tx_sg[1]) = tx_dummy_dma;
++                      }
++
++                      txd = dmaengine_prep_slave_sg(controller->tx_chan,
++                                      tx_sg, tx_nents, DMA_MEM_TO_DEV, 0);
++                      if (!txd) {
++                              ret = -ENOMEM;
++                              goto err_unmap;
++                      }
++
++                      atomic_inc(&controller->dma_outstanding);
++
++                      txd->callback = qup_dma_callback;
++                      txd->callback_param = controller;
++
++                      tx_cookie = dmaengine_submit(txd);
++
++                      dma_async_issue_pending(controller->tx_chan);
++              }
++
++              if (xfer->rx_buf) {
++                      /* recalc align for each transaction */
++                      rx_align = xfer_len % controller->in_blk_sz;
++
++                      if (rx_align)
++                              rx_nents = 2;
++                      else
++                              rx_nents = 1;
++
++                      /* initialize scatterlists */
++                      sg_init_table(rx_sg, rx_nents);
++                      sg_dma_address(&rx_sg[0]) = rx_dma + offset;
++                      sg_dma_len(&rx_sg[0]) = xfer_len - rx_align;
++
++                      /* account for non block size transfer */
++                      if (rx_align) {
++                              sg_dma_len(&rx_sg[1]) = controller->in_blk_sz;
++                              sg_dma_address(&rx_sg[1]) = rx_dummy_dma;
++                      }
++
++                      rxd = dmaengine_prep_slave_sg(controller->rx_chan,
++                                      rx_sg, rx_nents, DMA_DEV_TO_MEM, 0);
++                      if (!rxd) {
++                              ret = -ENOMEM;
++                              goto err_unmap;
++                      }
++
++                      atomic_inc(&controller->dma_outstanding);
++
++                      rxd->callback = qup_dma_callback;
++                      rxd->callback_param = controller;
++
++                      rx_cookie = dmaengine_submit(rxd);
++
++                      dma_async_issue_pending(controller->rx_chan);
++              }
++
++              if (spi_qup_set_state(controller, QUP_STATE_RUN)) {
++                      dev_warn(controller->dev, "cannot set EXECUTE state\n");
++                      goto err_unmap;
++              }
++
++              if (!wait_for_completion_timeout(&controller->done,
++                      msecs_to_jiffies(1000))) {
++                      ret = -ETIMEDOUT;
++
++                      /* clear out all the DMA transactions */
++                      if (xfer->tx_buf)
++                              dmaengine_terminate_all(controller->tx_chan);
++                      if (xfer->rx_buf)
++                              dmaengine_terminate_all(controller->rx_chan);
++
++                      goto err_unmap;
++              }
++
++              if (rx_align)
++                      memcpy(xfer->rx_buf + offset + xfer->len - rx_align,
++                              controller->dummy, rx_align);
++
++              /* adjust remaining bytes to transfer */
++              bytes_to_xfer -= xfer_len;
++              offset += xfer_len;
++
++
++              /* reset mini-core state so we can program next transaction */
++              if (spi_qup_set_state(controller, QUP_STATE_RESET)) {
++                      dev_err(controller->dev, "cannot set RESET state\n");
++                      goto err_unmap;
++              }
++      }
++
++      ret = 0;
++
++err_unmap:
++      if (tx_align)
++              dma_unmap_single(controller->dev, tx_dummy_dma,
++                      controller->out_fifo_sz, DMA_TO_DEVICE);
++err_map_tx_dummy:
++      if (xfer->tx_buf)
++              dma_unmap_single(controller->dev, tx_dma, xfer->len,
++                      DMA_TO_DEVICE);
++err_map_tx:
++      if (rx_align)
++              dma_unmap_single(controller->dev, rx_dummy_dma,
++                      controller->in_fifo_sz, DMA_FROM_DEVICE);
++err_map_rx_dummy:
++      if (xfer->rx_buf)
++              dma_unmap_single(controller->dev, rx_dma, xfer->len,
++                      DMA_FROM_DEVICE);
++
++      return ret;
++}
++
+ static irqreturn_t spi_qup_qup_irq(int irq, void *dev_id)
+ {
+       struct spi_qup *controller = dev_id;
+@@ -315,11 +545,13 @@ static irqreturn_t spi_qup_qup_irq(int i
+               error = -EIO;
+       }
+ 
+-      if (opflags & QUP_OP_IN_SERVICE_FLAG)
+-              spi_qup_fifo_read(controller, xfer);
++      if (!controller->use_dma) {
++              if (opflags & QUP_OP_IN_SERVICE_FLAG)
++                      spi_qup_fifo_read(controller, xfer);
+ 
+-      if (opflags & QUP_OP_OUT_SERVICE_FLAG)
+-              spi_qup_fifo_write(controller, xfer);
++              if (opflags & QUP_OP_OUT_SERVICE_FLAG)
++                      spi_qup_fifo_write(controller, xfer);
++      }
+ 
+       spin_lock_irqsave(&controller->lock, flags);
+       controller->error = error;
+@@ -339,6 +571,8 @@ static int spi_qup_io_config(struct spi_
+       struct spi_qup *controller = spi_master_get_devdata(spi->master);
+       u32 config, iomode, mode;
+       int ret, n_words, w_size;
++      size_t dma_align = dma_get_cache_alignment();
++      u32 dma_available = 0;
+ 
+       if (spi->mode & SPI_LOOP && xfer->len > controller->in_fifo_sz) {
+               dev_err(controller->dev, "too big size for loopback %d > %d\n",
+@@ -367,6 +601,11 @@ static int spi_qup_io_config(struct spi_
+       n_words = xfer->len / w_size;
+       controller->w_size = w_size;
+ 
++      if (controller->rx_chan &&
++              IS_ALIGNED((size_t)xfer->tx_buf, dma_align) &&
++              IS_ALIGNED((size_t)xfer->rx_buf, dma_align))
++              dma_available = 1;
++
+       if (n_words <= (controller->in_fifo_sz / sizeof(u32))) {
+               mode = QUP_IO_M_MODE_FIFO;
+               writel_relaxed(n_words, controller->base + QUP_MX_READ_CNT);
+@@ -374,19 +613,31 @@ static int spi_qup_io_config(struct spi_
+               /* must be zero for FIFO */
+               writel_relaxed(0, controller->base + QUP_MX_INPUT_CNT);
+               writel_relaxed(0, controller->base + QUP_MX_OUTPUT_CNT);
+-      } else {
++              controller->use_dma = 0;
++      } else if (!dma_available) {
+               mode = QUP_IO_M_MODE_BLOCK;
+               writel_relaxed(n_words, controller->base + QUP_MX_INPUT_CNT);
+               writel_relaxed(n_words, controller->base + QUP_MX_OUTPUT_CNT);
+               /* must be zero for BLOCK and BAM */
+               writel_relaxed(0, controller->base + QUP_MX_READ_CNT);
+               writel_relaxed(0, controller->base + QUP_MX_WRITE_CNT);
++              controller->use_dma = 0;
++      } else {
++              mode = QUP_IO_M_MODE_DMOV;
++              writel_relaxed(0, controller->base + QUP_MX_READ_CNT);
++              writel_relaxed(0, controller->base + QUP_MX_WRITE_CNT);
++              controller->use_dma = 1;
+       }
+ 
+       iomode = readl_relaxed(controller->base + QUP_IO_M_MODES);
+       /* Set input and output transfer mode */
+       iomode &= ~(QUP_IO_M_INPUT_MODE_MASK | QUP_IO_M_OUTPUT_MODE_MASK);
+-      iomode &= ~(QUP_IO_M_PACK_EN | QUP_IO_M_UNPACK_EN);
++
++      if (!controller->use_dma)
++              iomode &= ~(QUP_IO_M_PACK_EN | QUP_IO_M_UNPACK_EN);
++      else
++              iomode |= QUP_IO_M_PACK_EN | QUP_IO_M_UNPACK_EN;
++
+       iomode |= (mode << QUP_IO_M_OUTPUT_MODE_MASK_SHIFT);
+       iomode |= (mode << QUP_IO_M_INPUT_MODE_MASK_SHIFT);
+ 
+@@ -419,6 +670,14 @@ static int spi_qup_io_config(struct spi_
+       config &= ~(QUP_CONFIG_NO_INPUT | QUP_CONFIG_NO_OUTPUT | QUP_CONFIG_N);
+       config |= xfer->bits_per_word - 1;
+       config |= QUP_CONFIG_SPI_MODE;
++
++      if (controller->use_dma) {
++              if (!xfer->tx_buf)
++                      config |= QUP_CONFIG_NO_OUTPUT;
++              if (!xfer->rx_buf)
++                      config |= QUP_CONFIG_NO_INPUT;
++      }
++
+       writel_relaxed(config, controller->base + QUP_CONFIG);
+ 
+       /* only write to OPERATIONAL_MASK when register is present */
+@@ -452,25 +711,29 @@ static int spi_qup_transfer_one(struct s
+       controller->tx_bytes = 0;
+       spin_unlock_irqrestore(&controller->lock, flags);
+ 
+-      if (spi_qup_set_state(controller, QUP_STATE_RUN)) {
+-              dev_warn(controller->dev, "cannot set RUN state\n");
+-              goto exit;
+-      }
++      if (controller->use_dma) {
++              ret = spi_qup_do_dma(controller, xfer);
++      } else {
++              if (spi_qup_set_state(controller, QUP_STATE_RUN)) {
++                      dev_warn(controller->dev, "cannot set RUN state\n");
++                      goto exit;
++              }
+ 
+-      if (spi_qup_set_state(controller, QUP_STATE_PAUSE)) {
+-              dev_warn(controller->dev, "cannot set PAUSE state\n");
+-              goto exit;
+-      }
++              if (spi_qup_set_state(controller, QUP_STATE_PAUSE)) {
++                      dev_warn(controller->dev, "cannot set PAUSE state\n");
++                      goto exit;
++              }
+ 
+-      spi_qup_fifo_write(controller, xfer);
++              spi_qup_fifo_write(controller, xfer);
+ 
+-      if (spi_qup_set_state(controller, QUP_STATE_RUN)) {
+-              dev_warn(controller->dev, "cannot set EXECUTE state\n");
+-              goto exit;
+-      }
++              if (spi_qup_set_state(controller, QUP_STATE_RUN)) {
++                      dev_warn(controller->dev, "cannot set EXECUTE state\n");
++                      goto exit;
++              }
+ 
+-      if (!wait_for_completion_timeout(&controller->done, timeout))
+-              ret = -ETIMEDOUT;
++              if (!wait_for_completion_timeout(&controller->done, timeout))
++                      ret = -ETIMEDOUT;
++      }
+ exit:
+       spi_qup_set_state(controller, QUP_STATE_RESET);
+       spin_lock_irqsave(&controller->lock, flags);
+@@ -553,6 +816,7 @@ static int spi_qup_probe(struct platform
+       master->transfer_one = spi_qup_transfer_one;
+       master->dev.of_node = pdev->dev.of_node;
+       master->auto_runtime_pm = true;
++      master->dma_alignment = dma_get_cache_alignment();
+ 
+       platform_set_drvdata(pdev, master);
+ 
+@@ -618,6 +882,56 @@ static int spi_qup_probe(struct platform
+                       QUP_ERROR_INPUT_UNDER_RUN | QUP_ERROR_OUTPUT_UNDER_RUN,
+                       base + QUP_ERROR_FLAGS_EN);
+ 
++      /* allocate dma resources, if available */
++      controller->rx_chan = dma_request_slave_channel(&pdev->dev, "rx");
++      if (controller->rx_chan) {
++              controller->tx_chan =
++                      dma_request_slave_channel(&pdev->dev, "tx");
++
++              if (!controller->tx_chan) {
++                      dev_err(&pdev->dev, "Failed to allocate dma tx chan");
++                      dma_release_channel(controller->rx_chan);
++              }
++
++              /* set DMA parameters */
++              controller->rx_conf.device_fc = 1;
++              controller->rx_conf.src_addr = res->start + QUP_INPUT_FIFO;
++              controller->rx_conf.src_maxburst = controller->in_blk_sz;
++
++              controller->tx_conf.device_fc = 1;
++              controller->tx_conf.dst_addr = res->start + QUP_OUTPUT_FIFO;
++              controller->tx_conf.dst_maxburst = controller->out_blk_sz;
++
++              if (dmaengine_slave_config(controller->rx_chan,
++                              &controller->rx_conf)) {
++                      dev_err(&pdev->dev, "failed to configure RX channel\n");
++
++                      dma_release_channel(controller->rx_chan);
++                      dma_release_channel(controller->tx_chan);
++                      controller->tx_chan = NULL;
++                      controller->rx_chan = NULL;
++              } else if (dmaengine_slave_config(controller->tx_chan,
++                              &controller->tx_conf)) {
++                      dev_err(&pdev->dev, "failed to configure TX channel\n");
++
++                      dma_release_channel(controller->rx_chan);
++                      dma_release_channel(controller->tx_chan);
++                      controller->tx_chan = NULL;
++                      controller->rx_chan = NULL;
++              }
++
++              controller->dummy = devm_kmalloc(controller->dev, PAGE_SIZE,
++                      GFP_KERNEL);
++
++              if (!controller->dummy) {
++                      dma_release_channel(controller->rx_chan);
++                      dma_release_channel(controller->tx_chan);
++                      controller->tx_chan = NULL;
++                      controller->rx_chan = NULL;
++              }
++      }
++
++
+       writel_relaxed(0, base + SPI_CONFIG);
+       writel_relaxed(SPI_IO_C_NO_TRI_STATE, base + SPI_IO_CONTROL);
+ 
+@@ -730,6 +1044,11 @@ static int spi_qup_remove(struct platfor
+       if (ret)
+               return ret;
+ 
++      if (controller->rx_chan)
++              dma_release_channel(controller->rx_chan);
++      if (controller->tx_chan)
++              dma_release_channel(controller->tx_chan);
++
+       clk_disable_unprepare(controller->cclk);
+       clk_disable_unprepare(controller->iclk);
+ 
diff --git 
a/target/linux/ipq806x/patches/002-v3-spi-qup-Fix-incorrect-block-transfers.patch
 
b/target/linux/ipq806x/patches/002-v3-spi-qup-Fix-incorrect-block-transfers.patch
new file mode 100644
index 0000000..62ee5b4
--- /dev/null
+++ 
b/target/linux/ipq806x/patches/002-v3-spi-qup-Fix-incorrect-block-transfers.patch
@@ -0,0 +1,376 @@
+Content-Type: text/plain; charset="utf-8"
+MIME-Version: 1.0
+Content-Transfer-Encoding: 7bit
+Subject: [v3] spi: qup: Fix incorrect block transfers
+From: Andy Gross <[email protected]>
+X-Patchwork-Id: 5007321
+Message-Id: <[email protected]>
+To: Mark Brown <[email protected]>
+Cc: [email protected], [email protected],
+       [email protected], [email protected],
+       "Ivan T. Ivanov" <[email protected]>,
+       Bjorn Andersson <[email protected]>,
+       Kumar Gala <[email protected]>, Andy Gross <[email protected]>
+Date: Tue, 30 Sep 2014 16:21:28 -0500
+
+This patch fixes a number of errors with the QUP block transfer mode.  Errors
+manifested themselves as input underruns, output overruns, and timed out
+transactions.
+
+The block mode does not require the priming that occurs in FIFO mode.  At the
+moment that the QUP is placed into the RUN state, the QUP will immediately 
raise
+an interrupt if the request is a write.  Therefore, there is no need to prime
+the pump.
+
+In addition, the block transfers require that whole blocks of data are
+read/written at a time.  The last block of data that completes a transaction 
may
+contain less than a full blocks worth of data.
+
+Each block of data results in an input/output service interrupt accompanied 
with
+a input/output block flag set.  Additional block reads/writes require clearing
+of the service flag.  It is ok to check for additional blocks of data in the
+ISR, but you have to ack every block you transfer.  Imbalanced acks result in
+early return from complete transactions with pending interrupts that still have
+to be ack'd.  The next transaction can be affected by these interrupts.
+Transactions are deemed complete when the MAX_INPUT or MAX_OUTPUT flag are set.
+
+Changes from v2:
+- Added in additional completion check so that transaction done is not
+  prematurely signaled.
+- Fixed various review comments.
+
+Changes from v1:
+- Split out read/write block function.
+- Removed extraneous checks for transfer length
+
+Signed-off-by: Andy Gross <[email protected]>
+
+---
+drivers/spi/spi-qup.c |  201 ++++++++++++++++++++++++++++++++++++-------------
+ 1 file changed, 148 insertions(+), 53 deletions(-)
+
+--- a/drivers/spi/spi-qup.c
++++ b/drivers/spi/spi-qup.c
+@@ -82,6 +82,8 @@
+ #define QUP_IO_M_MODE_BAM             3
+ 
+ /* QUP_OPERATIONAL fields */
++#define QUP_OP_IN_BLOCK_READ_REQ      BIT(13)
++#define QUP_OP_OUT_BLOCK_WRITE_REQ    BIT(12)
+ #define QUP_OP_MAX_INPUT_DONE_FLAG    BIT(11)
+ #define QUP_OP_MAX_OUTPUT_DONE_FLAG   BIT(10)
+ #define QUP_OP_IN_SERVICE_FLAG                BIT(9)
+@@ -147,6 +149,7 @@ struct spi_qup {
+       int                     tx_bytes;
+       int                     rx_bytes;
+       int                     qup_v1;
++      int                     mode;
+ 
+       int                     use_dma;
+ 
+@@ -213,30 +216,14 @@ static int spi_qup_set_state(struct spi_
+       return 0;
+ }
+ 
+-
+-static void spi_qup_fifo_read(struct spi_qup *controller,
+-                          struct spi_transfer *xfer)
++static void spi_qup_fill_read_buffer(struct spi_qup *controller,
++      struct spi_transfer *xfer, u32 data)
+ {
+       u8 *rx_buf = xfer->rx_buf;
+-      u32 word, state;
+-      int idx, shift, w_size;
+-
+-      w_size = controller->w_size;
+-
+-      while (controller->rx_bytes < xfer->len) {
+-
+-              state = readl_relaxed(controller->base + QUP_OPERATIONAL);
+-              if (0 == (state & QUP_OP_IN_FIFO_NOT_EMPTY))
+-                      break;
+-
+-              word = readl_relaxed(controller->base + QUP_INPUT_FIFO);
+-
+-              if (!rx_buf) {
+-                      controller->rx_bytes += w_size;
+-                      continue;
+-              }
++      int idx, shift;
+ 
+-              for (idx = 0; idx < w_size; idx++, controller->rx_bytes++) {
++      if (rx_buf)
++              for (idx = 0; idx < controller->w_size; idx++) {
+                       /*
+                        * The data format depends on bytes per SPI word:
+                        *  4 bytes: 0x12345678
+@@ -244,41 +231,139 @@ static void spi_qup_fifo_read(struct spi
+                        *  1 byte : 0x00000012
+                        */
+                       shift = BITS_PER_BYTE;
+-                      shift *= (w_size - idx - 1);
+-                      rx_buf[controller->rx_bytes] = word >> shift;
++                      shift *= (controller->w_size - idx - 1);
++                      rx_buf[controller->rx_bytes + idx] = data >> shift;
++              }
++
++      controller->rx_bytes += controller->w_size;
++}
++
++static void spi_qup_prepare_write_data(struct spi_qup *controller,
++      struct spi_transfer *xfer, u32 *data)
++{
++      const u8 *tx_buf = xfer->tx_buf;
++      u32 val;
++      int idx;
++
++      *data = 0;
++
++      if (tx_buf)
++              for (idx = 0; idx < controller->w_size; idx++) {
++                      val = tx_buf[controller->tx_bytes + idx];
++                      *data |= val << (BITS_PER_BYTE * (3 - idx));
+               }
++
++      controller->tx_bytes += controller->w_size;
++}
++
++static void spi_qup_fifo_read(struct spi_qup *controller,
++                          struct spi_transfer *xfer)
++{
++      u32 data;
++
++      /* clear service request */
++      writel_relaxed(QUP_OP_IN_SERVICE_FLAG,
++                      controller->base + QUP_OPERATIONAL);
++
++      while (controller->rx_bytes < xfer->len) {
++              if (!(readl_relaxed(controller->base + QUP_OPERATIONAL) &
++                  QUP_OP_IN_FIFO_NOT_EMPTY))
++                      break;
++
++              data = readl_relaxed(controller->base + QUP_INPUT_FIFO);
++
++              spi_qup_fill_read_buffer(controller, xfer, data);
+       }
+ }
+ 
+ static void spi_qup_fifo_write(struct spi_qup *controller,
+-                          struct spi_transfer *xfer)
++      struct spi_transfer *xfer)
+ {
+-      const u8 *tx_buf = xfer->tx_buf;
+-      u32 word, state, data;
+-      int idx, w_size;
++      u32 data;
+ 
+-      w_size = controller->w_size;
++      /* clear service request */
++      writel_relaxed(QUP_OP_OUT_SERVICE_FLAG,
++              controller->base + QUP_OPERATIONAL);
+ 
+       while (controller->tx_bytes < xfer->len) {
+ 
+-              state = readl_relaxed(controller->base + QUP_OPERATIONAL);
+-              if (state & QUP_OP_OUT_FIFO_FULL)
++              if (readl_relaxed(controller->base + QUP_OPERATIONAL) &
++                              QUP_OP_OUT_FIFO_FULL)
+                       break;
+ 
+-              word = 0;
+-              for (idx = 0; idx < w_size; idx++, controller->tx_bytes++) {
++              spi_qup_prepare_write_data(controller, xfer, &data);
++              writel_relaxed(data, controller->base + QUP_OUTPUT_FIFO);
+ 
+-                      if (!tx_buf) {
+-                              controller->tx_bytes += w_size;
+-                              break;
+-                      }
++      }
++}
+ 
+-                      data = tx_buf[controller->tx_bytes];
+-                      word |= data << (BITS_PER_BYTE * (3 - idx));
+-              }
++static void spi_qup_block_read(struct spi_qup *controller,
++      struct spi_transfer *xfer)
++{
++      u32 data;
++      u32 reads_per_blk = controller->in_blk_sz >> 2;
++      u32 num_words = (xfer->len - controller->rx_bytes) / controller->w_size;
++      int i;
++
++      do {
++              /* ACK by clearing service flag */
++              writel_relaxed(QUP_OP_IN_SERVICE_FLAG,
++                      controller->base + QUP_OPERATIONAL);
++
++              /* transfer up to a block size of data in a single pass */
++              for (i = 0; num_words && i < reads_per_blk; i++, num_words--) {
++
++                      /* read data and fill up rx buffer */
++                      data = readl_relaxed(controller->base + QUP_INPUT_FIFO);
++                      spi_qup_fill_read_buffer(controller, xfer, data);
++              }
++
++              /* check to see if next block is ready */
++              if (!(readl_relaxed(controller->base + QUP_OPERATIONAL) &
++                      QUP_OP_IN_BLOCK_READ_REQ))
++                      break;
+ 
+-              writel_relaxed(word, controller->base + QUP_OUTPUT_FIFO);
+-      }
++      } while (num_words);
++
++      /*
++       * Due to extra stickiness of the QUP_OP_IN_SERVICE_FLAG during block
++       * reads, it has to be cleared again at the very end
++       */
++      if (readl_relaxed(controller->base + QUP_OPERATIONAL) &
++              QUP_OP_MAX_INPUT_DONE_FLAG)
++              writel_relaxed(QUP_OP_IN_SERVICE_FLAG,
++                      controller->base + QUP_OPERATIONAL);
++
++}
++
++static void spi_qup_block_write(struct spi_qup *controller,
++      struct spi_transfer *xfer)
++{
++      u32 data;
++      u32 writes_per_blk = controller->out_blk_sz >> 2;
++      u32 num_words = (xfer->len - controller->tx_bytes) / controller->w_size;
++      int i;
++
++      do {
++              /* ACK by clearing service flag */
++              writel_relaxed(QUP_OP_OUT_SERVICE_FLAG,
++                      controller->base + QUP_OPERATIONAL);
++
++              /* transfer up to a block size of data in a single pass */
++              for (i = 0; num_words && i < writes_per_blk; i++, num_words--) {
++
++                      /* swizzle the bytes for output and write out */
++                      spi_qup_prepare_write_data(controller, xfer, &data);
++                      writel_relaxed(data,
++                              controller->base + QUP_OUTPUT_FIFO);
++              }
++
++              /* check to see if next block is ready */
++              if (!(readl_relaxed(controller->base + QUP_OPERATIONAL) &
++                      QUP_OP_OUT_BLOCK_WRITE_REQ))
++                      break;
++
++      } while (num_words);
+ }
+ 
+ static void qup_dma_callback(void *data)
+@@ -515,9 +600,9 @@ static irqreturn_t spi_qup_qup_irq(int i
+ 
+       writel_relaxed(qup_err, controller->base + QUP_ERROR_FLAGS);
+       writel_relaxed(spi_err, controller->base + SPI_ERROR_FLAGS);
+-      writel_relaxed(opflags, controller->base + QUP_OPERATIONAL);
+ 
+       if (!xfer) {
++              writel_relaxed(opflags, controller->base + QUP_OPERATIONAL);
+               dev_err_ratelimited(controller->dev, "unexpected irq %08x %08x 
%08x\n",
+                                   qup_err, spi_err, opflags);
+               return IRQ_HANDLED;
+@@ -546,11 +631,19 @@ static irqreturn_t spi_qup_qup_irq(int i
+       }
+ 
+       if (!controller->use_dma) {
+-              if (opflags & QUP_OP_IN_SERVICE_FLAG)
+-                      spi_qup_fifo_read(controller, xfer);
++              if (opflags & QUP_OP_IN_SERVICE_FLAG) {
++                      if (opflags & QUP_OP_IN_BLOCK_READ_REQ)
++                              spi_qup_block_read(controller, xfer);
++                      else
++                              spi_qup_fifo_read(controller, xfer);
++              }
+ 
+-              if (opflags & QUP_OP_OUT_SERVICE_FLAG)
+-                      spi_qup_fifo_write(controller, xfer);
++              if (opflags & QUP_OP_OUT_SERVICE_FLAG) {
++                      if (opflags & QUP_OP_OUT_BLOCK_WRITE_REQ)
++                              spi_qup_block_write(controller, xfer);
++                      else
++                              spi_qup_fifo_write(controller, xfer);
++              }
+       }
+ 
+       spin_lock_irqsave(&controller->lock, flags);
+@@ -558,7 +651,8 @@ static irqreturn_t spi_qup_qup_irq(int i
+       controller->xfer = xfer;
+       spin_unlock_irqrestore(&controller->lock, flags);
+ 
+-      if (controller->rx_bytes == xfer->len || error)
++      if ((controller->rx_bytes == xfer->len &&
++              (opflags & QUP_OP_MAX_INPUT_DONE_FLAG)) || error)
+               complete(&controller->done);
+ 
+       return IRQ_HANDLED;
+@@ -569,7 +663,7 @@ static irqreturn_t spi_qup_qup_irq(int i
+ static int spi_qup_io_config(struct spi_device *spi, struct spi_transfer 
*xfer)
+ {
+       struct spi_qup *controller = spi_master_get_devdata(spi->master);
+-      u32 config, iomode, mode;
++      u32 config, iomode;
+       int ret, n_words, w_size;
+       size_t dma_align = dma_get_cache_alignment();
+       u32 dma_available = 0;
+@@ -607,7 +701,7 @@ static int spi_qup_io_config(struct spi_
+               dma_available = 1;
+ 
+       if (n_words <= (controller->in_fifo_sz / sizeof(u32))) {
+-              mode = QUP_IO_M_MODE_FIFO;
++              controller->mode = QUP_IO_M_MODE_FIFO;
+               writel_relaxed(n_words, controller->base + QUP_MX_READ_CNT);
+               writel_relaxed(n_words, controller->base + QUP_MX_WRITE_CNT);
+               /* must be zero for FIFO */
+@@ -615,7 +709,7 @@ static int spi_qup_io_config(struct spi_
+               writel_relaxed(0, controller->base + QUP_MX_OUTPUT_CNT);
+               controller->use_dma = 0;
+       } else if (!dma_available) {
+-              mode = QUP_IO_M_MODE_BLOCK;
++              controller->mode = QUP_IO_M_MODE_BLOCK;
+               writel_relaxed(n_words, controller->base + QUP_MX_INPUT_CNT);
+               writel_relaxed(n_words, controller->base + QUP_MX_OUTPUT_CNT);
+               /* must be zero for BLOCK and BAM */
+@@ -623,7 +717,7 @@ static int spi_qup_io_config(struct spi_
+               writel_relaxed(0, controller->base + QUP_MX_WRITE_CNT);
+               controller->use_dma = 0;
+       } else {
+-              mode = QUP_IO_M_MODE_DMOV;
++              controller->mode = QUP_IO_M_MODE_DMOV;
+               writel_relaxed(0, controller->base + QUP_MX_READ_CNT);
+               writel_relaxed(0, controller->base + QUP_MX_WRITE_CNT);
+               controller->use_dma = 1;
+@@ -638,8 +732,8 @@ static int spi_qup_io_config(struct spi_
+       else
+               iomode |= QUP_IO_M_PACK_EN | QUP_IO_M_UNPACK_EN;
+ 
+-      iomode |= (mode << QUP_IO_M_OUTPUT_MODE_MASK_SHIFT);
+-      iomode |= (mode << QUP_IO_M_INPUT_MODE_MASK_SHIFT);
++      iomode |= (controller->mode << QUP_IO_M_OUTPUT_MODE_MASK_SHIFT);
++      iomode |= (controller->mode << QUP_IO_M_INPUT_MODE_MASK_SHIFT);
+ 
+       writel_relaxed(iomode, controller->base + QUP_IO_M_MODES);
+ 
+@@ -724,7 +818,8 @@ static int spi_qup_transfer_one(struct s
+                       goto exit;
+               }
+ 
+-              spi_qup_fifo_write(controller, xfer);
++              if (controller->mode == QUP_IO_M_MODE_FIFO)
++                      spi_qup_fifo_write(controller, xfer);
+ 
+               if (spi_qup_set_state(controller, QUP_STATE_RUN)) {
+                       dev_warn(controller->dev, "cannot set EXECUTE state\n");
+@@ -741,6 +836,7 @@ exit:
+       if (!ret)
+               ret = controller->error;
+       spin_unlock_irqrestore(&controller->lock, flags);
++
+       return ret;
+ }
+ 
-- 
1.9.1
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