bcm63xx: fix spi transfer handling
authorJonas Gorski <jogo@openwrt.org>
Sat, 24 Nov 2012 14:19:09 +0000 (14:19 +0000)
committerJonas Gorski <jogo@openwrt.org>
Sat, 24 Nov 2012 14:19:09 +0000 (14:19 +0000)
* Accept transfers without bits_per_word set.

* Work around the inability of the hardware of keeping CS asserted.

Signed-off-by: Jonas Gorski <jogo@openwrt.org>
SVN-Revision: 34320

target/linux/brcm63xx/patches-3.3/109-bcm63xx-fix-transfer-bits_per_words-check.patch [new file with mode: 0644]
target/linux/brcm63xx/patches-3.3/110-spi-bcm63xx-fix-multi-transfer-messages.patch [new file with mode: 0644]
target/linux/brcm63xx/patches-3.3/404-bcm963xx_flashmap.patch
target/linux/brcm63xx/patches-3.6/106-bcm63xx-fix-transfer-bits_per_words-check.patch [new file with mode: 0644]
target/linux/brcm63xx/patches-3.6/107-spi-bcm63xx-fix-multi-transfer-messages.patch [new file with mode: 0644]

diff --git a/target/linux/brcm63xx/patches-3.3/109-bcm63xx-fix-transfer-bits_per_words-check.patch b/target/linux/brcm63xx/patches-3.3/109-bcm63xx-fix-transfer-bits_per_words-check.patch
new file mode 100644 (file)
index 0000000..37d9d49
--- /dev/null
@@ -0,0 +1,29 @@
+From fbef4dff80be6254e36ab5b9c655d248a3991ded Mon Sep 17 00:00:00 2001
+From: Jonas Gorski <jonas.gorski@gmail.com>
+Date: Sat, 24 Nov 2012 12:08:22 +0100
+Subject: [PATCH 3.7] spi/bcm63xx: fix transfer bits_per_words check
+
+Transfers often do not have bits_per_words set, so use the spi device's
+bits_per_words in this case.
+
+This fixes the driver rejecting valid transfers e.g. generated by
+spi_write() or spi_read().
+
+Cc: stable@vger.kernel.org
+Signed-off-by: Jonas Gorski <jonas.gorski@gmail.com>
+---
+ drivers/spi/spi-bcm63xx.c |    3 ++-
+ 1 file changed, 2 insertions(+), 1 deletion(-)
+
+--- a/drivers/spi/spi-bcm63xx.c
++++ b/drivers/spi/spi-bcm63xx.c
+@@ -103,7 +103,8 @@ static int bcm63xx_spi_check_transfer(st
+ {
+       u8 bits_per_word;
+-      bits_per_word = (t) ? t->bits_per_word : spi->bits_per_word;
++      bits_per_word = (t && t->bits_per_word) ?
++                      t->bits_per_word : spi->bits_per_word;
+       if (bits_per_word != 8) {
+               dev_err(&spi->dev, "%s, unsupported bits_per_word=%d\n",
+                       __func__, bits_per_word);
diff --git a/target/linux/brcm63xx/patches-3.3/110-spi-bcm63xx-fix-multi-transfer-messages.patch b/target/linux/brcm63xx/patches-3.3/110-spi-bcm63xx-fix-multi-transfer-messages.patch
new file mode 100644 (file)
index 0000000..941de48
--- /dev/null
@@ -0,0 +1,279 @@
+From 0f2ae1e1282ff64f74a5e36f7da874f94911225e Mon Sep 17 00:00:00 2001
+From: Jonas Gorski <jonas.gorski@gmail.com>
+Date: Wed, 14 Nov 2012 22:22:33 +0100
+Subject: [PATCH] spi/bcm63xx: fix multi transfer messages
+
+The BCM63XX SPI controller does not support keeping CS asserted after
+sending its buffer. This breaks common usages like spi_write_then_read,
+where it is expected to be kept active during the whole transfers.
+
+Work around this by combining the transfers into one if the buffer
+allows. For spi_write_then_read, use the prepend byte feature to write
+to "prepend" the write if it is less than 15 bytes, allowing the whole
+fifo size for the read.
+
+Signed-off-by: Jonas Gorski <jonas.gorski@gmail.com>
+---
+Tested on a SPI conntected switch which required keeping CS active between
+the register read command and reading the register contents.
+
+Based on Mark's spi/next.
+
+Not sure if this is stable material, as it's quite invasive.
+
+ drivers/spi/spi-bcm63xx.c |  172 ++++++++++++++++++++++++++++++---------------
+ 1 file changed, 117 insertions(+), 55 deletions(-)
+
+--- a/drivers/spi/spi-bcm63xx.c
++++ b/drivers/spi/spi-bcm63xx.c
+@@ -38,6 +38,8 @@
+ #define PFX           KBUILD_MODNAME
+ #define DRV_VER               "0.1.2"
++#define BCM63XX_SPI_MAX_PREPEND               15
++
+ struct bcm63xx_spi {
+       struct completion       done;
+@@ -50,16 +52,10 @@ struct bcm63xx_spi {
+       unsigned int            msg_type_shift;
+       unsigned int            msg_ctl_width;
+-      /* Data buffers */
+-      const unsigned char     *tx_ptr;
+-      unsigned char           *rx_ptr;
+-
+       /* data iomem */
+       u8 __iomem              *tx_io;
+       const u8 __iomem        *rx_io;
+-      int                     remaining_bytes;
+-
+       struct clk              *clk;
+       struct platform_device  *pdev;
+ };
+@@ -184,50 +180,60 @@ static int bcm63xx_spi_setup(struct spi_
+       return 0;
+ }
+-/* Fill the TX FIFO with as many bytes as possible */
+-static void bcm63xx_spi_fill_tx_fifo(struct bcm63xx_spi *bs)
+-{
+-      u8 size;
+-
+-      /* Fill the Tx FIFO with as many bytes as possible */
+-      size = bs->remaining_bytes < bs->fifo_size ? bs->remaining_bytes :
+-              bs->fifo_size;
+-      memcpy_toio(bs->tx_io, bs->tx_ptr, size);
+-      bs->remaining_bytes -= size;
+-}
+-
+ static unsigned int bcm63xx_txrx_bufs(struct spi_device *spi,
+-                                      struct spi_transfer *t)
++                                      struct spi_transfer *first,
++                                      unsigned int n_transfers)
+ {
+       struct bcm63xx_spi *bs = spi_master_get_devdata(spi->master);
+       u16 msg_ctl;
+       u16 cmd;
++      unsigned int i, timeout, total_len = 0, prepend_len = 0, len = 0;
++      struct spi_transfer *t = first;
++      u8 rx_tail;
++      bool do_rx = false;
++      bool do_tx = false;
+       /* Disable the CMD_DONE interrupt */
+       bcm_spi_writeb(bs, 0, SPI_INT_MASK);
+-      dev_dbg(&spi->dev, "txrx: tx %p, rx %p, len %d\n",
+-              t->tx_buf, t->rx_buf, t->len);
++      if (n_transfers > 1 && t->tx_buf && t->len <= BCM63XX_SPI_MAX_PREPEND)
++              prepend_len = t->len;
++
++      /* prepare the buffer */
++      for (i = 0; i < n_transfers; i++) {
++              if (t->tx_buf) {
++                      do_tx = true;
++                      memcpy_toio(bs->tx_io + total_len, t->tx_buf, t->len);
++
++                      /* don't prepend more than one tx */
++                      if (t != first)
++                              prepend_len = 0;
++              }
++
++              if (t->rx_buf) {
++                      do_rx = true;
++                      if (t == first)
++                              prepend_len = 0;
++              }
+-      /* Transmitter is inhibited */
+-      bs->tx_ptr = t->tx_buf;
+-      bs->rx_ptr = t->rx_buf;
+-
+-      if (t->tx_buf) {
+-              bs->remaining_bytes = t->len;
+-              bcm63xx_spi_fill_tx_fifo(bs);
++              total_len += t->len;
++
++              t = list_entry(t->transfer_list.next, struct spi_transfer,
++                             transfer_list);
+       }
++      len = total_len - prepend_len;
++
+       init_completion(&bs->done);
+       /* Fill in the Message control register */
+-      msg_ctl = (t->len << SPI_BYTE_CNT_SHIFT);
++      msg_ctl = (len << SPI_BYTE_CNT_SHIFT);
+-      if (t->rx_buf && t->tx_buf)
++      if (do_rx && do_tx && prepend_len == 0)
+               msg_ctl |= (SPI_FD_RW << bs->msg_type_shift);
+-      else if (t->rx_buf)
++      else if (do_rx)
+               msg_ctl |= (SPI_HD_R << bs->msg_type_shift);
+-      else if (t->tx_buf)
++      else if (do_tx)
+               msg_ctl |= (SPI_HD_W << bs->msg_type_shift);
+       switch (bs->msg_ctl_width) {
+@@ -245,14 +251,41 @@ static unsigned int bcm63xx_txrx_bufs(st
+       /* Issue the transfer */
+       cmd = SPI_CMD_START_IMMEDIATE;
+-      cmd |= (0 << SPI_CMD_PREPEND_BYTE_CNT_SHIFT);
++      cmd |= (prepend_len << SPI_CMD_PREPEND_BYTE_CNT_SHIFT);
+       cmd |= (spi->chip_select << SPI_CMD_DEVICE_ID_SHIFT);
+       bcm_spi_writew(bs, cmd, SPI_CMD);
+       /* Enable the CMD_DONE interrupt */
+       bcm_spi_writeb(bs, SPI_INTR_CMD_DONE, SPI_INT_MASK);
+-      return t->len - bs->remaining_bytes;
++      timeout = wait_for_completion_timeout(&bs->done, HZ);
++      if (!timeout)
++              return -ETIMEDOUT;
++
++      /* read out all data */
++      rx_tail = bcm_spi_readb(bs, SPI_RX_TAIL);
++
++      if (do_rx && rx_tail != len)
++              return -EINVAL;
++
++      if (!rx_tail)
++              return total_len;
++
++      len = 0;
++      t = first;
++      /* Read out all the data */
++      for (i = 0; i < n_transfers; i++) {
++              if (t->rx_buf)
++                      memcpy_fromio(t->rx_buf, bs->rx_io + len, t->len);
++
++              if (t != first || prepend_len == 0)
++                      len += t->len;
++
++              t = list_entry(t->transfer_list.next, struct spi_transfer,
++                             transfer_list);
++      }
++
++      return total_len;
+ }
+ static int bcm63xx_spi_prepare_transfer(struct spi_master *master)
+@@ -277,42 +310,71 @@ static int bcm63xx_spi_transfer_one(stru
+                                       struct spi_message *m)
+ {
+       struct bcm63xx_spi *bs = spi_master_get_devdata(master);
+-      struct spi_transfer *t;
++      struct spi_transfer *t, *first = NULL;
+       struct spi_device *spi = m->spi;
+       int status = 0;
+-      unsigned int timeout = 0;
++      unsigned int n_transfers = 0, total_len = 0;
++      bool can_use_prepend = false;
++      /*
++       * This SPI controller does not support keeping CS active after a
++       * transfer, so we need to combine the transfers into one until we may
++       * deassert CS.
++       */
+       list_for_each_entry(t, &m->transfers, transfer_list) {
+-              unsigned int len = t->len;
+-              u8 rx_tail;
+-
+               status = bcm63xx_spi_check_transfer(spi, t);
+               if (status < 0)
+                       goto exit;
+-              /* configure adapter for a new transfer */
+-              bcm63xx_spi_setup_transfer(spi, t);
++              if (!first)
++                      first = t;
+-              while (len) {
+-                      /* send the data */
+-                      len -= bcm63xx_txrx_bufs(spi, t);
+-
+-                      timeout = wait_for_completion_timeout(&bs->done, HZ);
+-                      if (!timeout) {
+-                              status = -ETIMEDOUT;
+-                              goto exit;
+-                      }
++              n_transfers++;
++              total_len += t->len;
++
++              if (n_transfers == 2 && !first->rx_buf && !t->tx_buf &&
++                  first->len <= BCM63XX_SPI_MAX_PREPEND)
++                      can_use_prepend = true;
++              else if (can_use_prepend && t->tx_buf)
++                      can_use_prepend = false;
++
++              if ((can_use_prepend &&
++                   total_len > (bs->fifo_size + BCM63XX_SPI_MAX_PREPEND)) ||
++                  (!can_use_prepend && total_len > bs->fifo_size)) {
++                      status = -EINVAL;
++                      goto exit;
++              }
+-                      /* read out all data */
+-                      rx_tail = bcm_spi_readb(bs, SPI_RX_TAIL);
++              /* all transfers have to be made at the same speed */
++              if (t->speed_hz != first->speed_hz) {
++                      status = -EINVAL;
++                      goto exit;
++              }
+-                      /* Read out all the data */
+-                      if (rx_tail)
+-                              memcpy_fromio(bs->rx_ptr, bs->rx_io, rx_tail);
++              /* CS will be deasserted directly after the transfer */
++              if (t->delay_usecs) {
++                      status = -EINVAL;
++                      goto exit;
+               }
+-              m->actual_length += t->len;
++              if (t->cs_change ||
++                  list_is_last(&t->transfer_list, &m->transfers)) {
++                      /* configure adapter for a new transfer */
++                      bcm63xx_spi_setup_transfer(spi, first);
++
++                      status = bcm63xx_txrx_bufs(spi, first, n_transfers);
++                      if (status < 0)
++                              goto exit;
++
++                      m->actual_length += status;
++                      first = NULL;
++                      status = 0;
++                      n_transfers = 0;
++                      total_len = 0;
++                      can_use_prepend = false;
++              }
+       }
++
+ exit:
+       m->status = status;
+       spi_finalize_current_message(master);
index 8338962e5bd9eafcd25c5109a1e6d317c9d6d5ed..8f91623c8abb0ddacbbd575031740dbb2f191a2c 100644 (file)
@@ -23,7 +23,7 @@ Signed-off-by: Axel Gembe <ago@bastart.eu.org>
        .width                  = 2,
 --- a/drivers/mtd/redboot.c
 +++ b/drivers/mtd/redboot.c
-@@ -75,6 +75,7 @@ static int parse_redboot_partitions(stru
+@@ -72,6 +72,7 @@ static int parse_redboot_partitions(stru
        int nulllen = 0;
        int numslots;
        unsigned long offset;
@@ -31,7 +31,7 @@ Signed-off-by: Axel Gembe <ago@bastart.eu.org>
  #ifdef CONFIG_MTD_REDBOOT_PARTS_UNALLOCATED
        static char nullstring[] = "unallocated";
  #endif
-@@ -181,6 +182,16 @@ static int parse_redboot_partitions(stru
+@@ -178,6 +179,16 @@ static int parse_redboot_partitions(stru
                goto out;
        }
  
@@ -48,7 +48,7 @@ Signed-off-by: Axel Gembe <ago@bastart.eu.org>
        for (i = 0; i < numslots; i++) {
                struct fis_list *new_fl, **prev;
  
-@@ -201,10 +212,10 @@ static int parse_redboot_partitions(stru
+@@ -198,10 +209,10 @@ static int parse_redboot_partitions(stru
                        goto out;
                }
                new_fl->img = &buf[i];
diff --git a/target/linux/brcm63xx/patches-3.6/106-bcm63xx-fix-transfer-bits_per_words-check.patch b/target/linux/brcm63xx/patches-3.6/106-bcm63xx-fix-transfer-bits_per_words-check.patch
new file mode 100644 (file)
index 0000000..37d9d49
--- /dev/null
@@ -0,0 +1,29 @@
+From fbef4dff80be6254e36ab5b9c655d248a3991ded Mon Sep 17 00:00:00 2001
+From: Jonas Gorski <jonas.gorski@gmail.com>
+Date: Sat, 24 Nov 2012 12:08:22 +0100
+Subject: [PATCH 3.7] spi/bcm63xx: fix transfer bits_per_words check
+
+Transfers often do not have bits_per_words set, so use the spi device's
+bits_per_words in this case.
+
+This fixes the driver rejecting valid transfers e.g. generated by
+spi_write() or spi_read().
+
+Cc: stable@vger.kernel.org
+Signed-off-by: Jonas Gorski <jonas.gorski@gmail.com>
+---
+ drivers/spi/spi-bcm63xx.c |    3 ++-
+ 1 file changed, 2 insertions(+), 1 deletion(-)
+
+--- a/drivers/spi/spi-bcm63xx.c
++++ b/drivers/spi/spi-bcm63xx.c
+@@ -103,7 +103,8 @@ static int bcm63xx_spi_check_transfer(st
+ {
+       u8 bits_per_word;
+-      bits_per_word = (t) ? t->bits_per_word : spi->bits_per_word;
++      bits_per_word = (t && t->bits_per_word) ?
++                      t->bits_per_word : spi->bits_per_word;
+       if (bits_per_word != 8) {
+               dev_err(&spi->dev, "%s, unsupported bits_per_word=%d\n",
+                       __func__, bits_per_word);
diff --git a/target/linux/brcm63xx/patches-3.6/107-spi-bcm63xx-fix-multi-transfer-messages.patch b/target/linux/brcm63xx/patches-3.6/107-spi-bcm63xx-fix-multi-transfer-messages.patch
new file mode 100644 (file)
index 0000000..2da5044
--- /dev/null
@@ -0,0 +1,279 @@
+From 0f2ae1e1282ff64f74a5e36f7da874f94911225e Mon Sep 17 00:00:00 2001
+From: Jonas Gorski <jonas.gorski@gmail.com>
+Date: Wed, 14 Nov 2012 22:22:33 +0100
+Subject: [PATCH] spi/bcm63xx: fix multi transfer messages
+
+The BCM63XX SPI controller does not support keeping CS asserted after
+sending its buffer. This breaks common usages like spi_write_then_read,
+where it is expected to be kept active during the whole transfers.
+
+Work around this by combining the transfers into one if the buffer
+allows. For spi_write_then_read, use the prepend byte feature to write
+to "prepend" the write if it is less than 15 bytes, allowing the whole
+fifo size for the read.
+
+Signed-off-by: Jonas Gorski <jonas.gorski@gmail.com>
+---
+Tested on a SPI conntected switch which required keeping CS active between
+the register read command and reading the register contents.
+
+Based on Mark's spi/next.
+
+Not sure if this is stable material, as it's quite invasive.
+
+ drivers/spi/spi-bcm63xx.c |  172 ++++++++++++++++++++++++++++++---------------
+ 1 file changed, 117 insertions(+), 55 deletions(-)
+
+--- a/drivers/spi/spi-bcm63xx.c
++++ b/drivers/spi/spi-bcm63xx.c
+@@ -38,6 +38,8 @@
+ #define PFX           KBUILD_MODNAME
+ #define DRV_VER               "0.1.2"
++#define BCM63XX_SPI_MAX_PREPEND               15
++
+ struct bcm63xx_spi {
+       struct completion       done;
+@@ -50,16 +52,10 @@ struct bcm63xx_spi {
+       unsigned int            msg_type_shift;
+       unsigned int            msg_ctl_width;
+-      /* Data buffers */
+-      const unsigned char     *tx_ptr;
+-      unsigned char           *rx_ptr;
+-
+       /* data iomem */
+       u8 __iomem              *tx_io;
+       const u8 __iomem        *rx_io;
+-      int                     remaining_bytes;
+-
+       struct clk              *clk;
+       struct platform_device  *pdev;
+ };
+@@ -184,50 +180,60 @@ static int bcm63xx_spi_setup(struct spi_
+       return 0;
+ }
+-/* Fill the TX FIFO with as many bytes as possible */
+-static void bcm63xx_spi_fill_tx_fifo(struct bcm63xx_spi *bs)
+-{
+-      u8 size;
+-
+-      /* Fill the Tx FIFO with as many bytes as possible */
+-      size = bs->remaining_bytes < bs->fifo_size ? bs->remaining_bytes :
+-              bs->fifo_size;
+-      memcpy_toio(bs->tx_io, bs->tx_ptr, size);
+-      bs->remaining_bytes -= size;
+-}
+-
+ static unsigned int bcm63xx_txrx_bufs(struct spi_device *spi,
+-                                      struct spi_transfer *t)
++                                      struct spi_transfer *first,
++                                      unsigned int n_transfers)
+ {
+       struct bcm63xx_spi *bs = spi_master_get_devdata(spi->master);
+       u16 msg_ctl;
+       u16 cmd;
++      unsigned int i, timeout, total_len = 0, prepend_len = 0, len = 0;
++      struct spi_transfer *t = first;
++      u8 rx_tail;
++      bool do_rx = false;
++      bool do_tx = false;
+       /* Disable the CMD_DONE interrupt */
+       bcm_spi_writeb(bs, 0, SPI_INT_MASK);
+-      dev_dbg(&spi->dev, "txrx: tx %p, rx %p, len %d\n",
+-              t->tx_buf, t->rx_buf, t->len);
++      if (n_transfers > 1 && t->tx_buf && t->len <= BCM63XX_SPI_MAX_PREPEND)
++              prepend_len = t->len;
++
++      /* prepare the buffer */
++      for (i = 0; i < n_transfers; i++) {
++              if (t->tx_buf) {
++                      do_tx = true;
++                      memcpy_toio(bs->tx_io + total_len, t->tx_buf, t->len);
++
++                      /* don't prepend more than one tx */
++                      if (t != first)
++                              prepend_len = 0;
++              }
++
++              if (t->rx_buf) {
++                      do_rx = true;
++                      if (t == first)
++                              prepend_len = 0;
++              }
+-      /* Transmitter is inhibited */
+-      bs->tx_ptr = t->tx_buf;
+-      bs->rx_ptr = t->rx_buf;
+-
+-      if (t->tx_buf) {
+-              bs->remaining_bytes = t->len;
+-              bcm63xx_spi_fill_tx_fifo(bs);
++              total_len += t->len;
++
++              t = list_entry(t->transfer_list.next, struct spi_transfer,
++                             transfer_list);
+       }
++      len = total_len - prepend_len;
++
+       init_completion(&bs->done);
+       /* Fill in the Message control register */
+-      msg_ctl = (t->len << SPI_BYTE_CNT_SHIFT);
++      msg_ctl = (len << SPI_BYTE_CNT_SHIFT);
+-      if (t->rx_buf && t->tx_buf)
++      if (do_rx && do_tx && prepend_len == 0)
+               msg_ctl |= (SPI_FD_RW << bs->msg_type_shift);
+-      else if (t->rx_buf)
++      else if (do_rx)
+               msg_ctl |= (SPI_HD_R << bs->msg_type_shift);
+-      else if (t->tx_buf)
++      else if (do_tx)
+               msg_ctl |= (SPI_HD_W << bs->msg_type_shift);
+       switch (bs->msg_ctl_width) {
+@@ -241,14 +247,41 @@ static unsigned int bcm63xx_txrx_bufs(st
+       /* Issue the transfer */
+       cmd = SPI_CMD_START_IMMEDIATE;
+-      cmd |= (0 << SPI_CMD_PREPEND_BYTE_CNT_SHIFT);
++      cmd |= (prepend_len << SPI_CMD_PREPEND_BYTE_CNT_SHIFT);
+       cmd |= (spi->chip_select << SPI_CMD_DEVICE_ID_SHIFT);
+       bcm_spi_writew(bs, cmd, SPI_CMD);
+       /* Enable the CMD_DONE interrupt */
+       bcm_spi_writeb(bs, SPI_INTR_CMD_DONE, SPI_INT_MASK);
+-      return t->len - bs->remaining_bytes;
++      timeout = wait_for_completion_timeout(&bs->done, HZ);
++      if (!timeout)
++              return -ETIMEDOUT;
++
++      /* read out all data */
++      rx_tail = bcm_spi_readb(bs, SPI_RX_TAIL);
++
++      if (do_rx && rx_tail != len)
++              return -EINVAL;
++
++      if (!rx_tail)
++              return total_len;
++
++      len = 0;
++      t = first;
++      /* Read out all the data */
++      for (i = 0; i < n_transfers; i++) {
++              if (t->rx_buf)
++                      memcpy_fromio(t->rx_buf, bs->rx_io + len, t->len);
++
++              if (t != first || prepend_len == 0)
++                      len += t->len;
++
++              t = list_entry(t->transfer_list.next, struct spi_transfer,
++                             transfer_list);
++      }
++
++      return total_len;
+ }
+ static int bcm63xx_spi_prepare_transfer(struct spi_master *master)
+@@ -273,42 +306,71 @@ static int bcm63xx_spi_transfer_one(stru
+                                       struct spi_message *m)
+ {
+       struct bcm63xx_spi *bs = spi_master_get_devdata(master);
+-      struct spi_transfer *t;
++      struct spi_transfer *t, *first = NULL;
+       struct spi_device *spi = m->spi;
+       int status = 0;
+-      unsigned int timeout = 0;
++      unsigned int n_transfers = 0, total_len = 0;
++      bool can_use_prepend = false;
++      /*
++       * This SPI controller does not support keeping CS active after a
++       * transfer, so we need to combine the transfers into one until we may
++       * deassert CS.
++       */
+       list_for_each_entry(t, &m->transfers, transfer_list) {
+-              unsigned int len = t->len;
+-              u8 rx_tail;
+-
+               status = bcm63xx_spi_check_transfer(spi, t);
+               if (status < 0)
+                       goto exit;
+-              /* configure adapter for a new transfer */
+-              bcm63xx_spi_setup_transfer(spi, t);
++              if (!first)
++                      first = t;
+-              while (len) {
+-                      /* send the data */
+-                      len -= bcm63xx_txrx_bufs(spi, t);
+-
+-                      timeout = wait_for_completion_timeout(&bs->done, HZ);
+-                      if (!timeout) {
+-                              status = -ETIMEDOUT;
+-                              goto exit;
+-                      }
++              n_transfers++;
++              total_len += t->len;
++
++              if (n_transfers == 2 && !first->rx_buf && !t->tx_buf &&
++                  first->len <= BCM63XX_SPI_MAX_PREPEND)
++                      can_use_prepend = true;
++              else if (can_use_prepend && t->tx_buf)
++                      can_use_prepend = false;
++
++              if ((can_use_prepend &&
++                   total_len > (bs->fifo_size + BCM63XX_SPI_MAX_PREPEND)) ||
++                  (!can_use_prepend && total_len > bs->fifo_size)) {
++                      status = -EINVAL;
++                      goto exit;
++              }
+-                      /* read out all data */
+-                      rx_tail = bcm_spi_readb(bs, SPI_RX_TAIL);
++              /* all transfers have to be made at the same speed */
++              if (t->speed_hz != first->speed_hz) {
++                      status = -EINVAL;
++                      goto exit;
++              }
+-                      /* Read out all the data */
+-                      if (rx_tail)
+-                              memcpy_fromio(bs->rx_ptr, bs->rx_io, rx_tail);
++              /* CS will be deasserted directly after the transfer */
++              if (t->delay_usecs) {
++                      status = -EINVAL;
++                      goto exit;
+               }
+-              m->actual_length += t->len;
++              if (t->cs_change ||
++                  list_is_last(&t->transfer_list, &m->transfers)) {
++                      /* configure adapter for a new transfer */
++                      bcm63xx_spi_setup_transfer(spi, first);
++
++                      status = bcm63xx_txrx_bufs(spi, first, n_transfers);
++                      if (status < 0)
++                              goto exit;
++
++                      m->actual_length += status;
++                      first = NULL;
++                      status = 0;
++                      n_transfers = 0;
++                      total_len = 0;
++                      can_use_prepend = false;
++              }
+       }
++
+ exit:
+       m->status = status;
+       spi_finalize_current_message(master);