3 files changed, 77 insertions, 14 deletions

diff --git a/drivers/spi/spi_bitbang.c b/drivers/spi/spi_bitbang.c
index f037e5593269..0525c99118c3 100644
--- a/drivers/spi/spi_bitbang.c
+++ b/drivers/spi/spi_bitbang.c
@@ -138,6 +138,43 @@ static unsigned bitbang_txrx_32(
         return t->len - count;
 }
 
+static int
+bitbang_transfer_setup(struct spi_device *spi, struct spi_transfer *t)
+{
+        struct spi_bitbang_cs   *cs = spi->controller_state;
+        u8                      bits_per_word;
+        u32                     hz;
+
+        if (t) {
+                bits_per_word = t->bits_per_word;
+                hz = t->speed_hz;
+        } else {
+                bits_per_word = 0;
+                hz = 0;
+        }
+
+        /* spi_transfer level calls that work per-word */
+        if (!bits_per_word)
+                bits_per_word = spi->bits_per_word;
+        if (bits_per_word <= 8)
+                cs->txrx_bufs = bitbang_txrx_8;
+        else if (bits_per_word <= 16)
+                cs->txrx_bufs = bitbang_txrx_16;
+        else if (bits_per_word <= 32)
+                cs->txrx_bufs = bitbang_txrx_32;
+        else
+                return -EINVAL;
+
+        /* nsecs = (clock period)/2 */
+        if (!hz)
+                hz = spi->max_speed_hz;
+        cs->nsecs = (1000000000/2) / hz;
+        if (cs->nsecs > MAX_UDELAY_MS * 1000)
+                return -EINVAL;
+
+        return 0;
+}
+
 /**
  * spi_bitbang_setup - default setup for per-word I/O loops
  */
@@ -145,6 +182,7 @@ int spi_bitbang_setup(struct spi_device *spi)
 {
         struct spi_bitbang_cs   *cs = spi->controller_state;
         struct spi_bitbang      *bitbang;
+        int                     retval;
 
         if (!spi->max_speed_hz)
                 return -EINVAL;
@@ -160,25 +198,14 @@ int spi_bitbang_setup(struct spi_device *spi)
         if (!spi->bits_per_word)
                 spi->bits_per_word = 8;
 
-        /* spi_transfer level calls that work per-word */
-        if (spi->bits_per_word <= 8)
-                cs->txrx_bufs = bitbang_txrx_8;
-        else if (spi->bits_per_word <= 16)
-                cs->txrx_bufs = bitbang_txrx_16;
-        else if (spi->bits_per_word <= 32)
-                cs->txrx_bufs = bitbang_txrx_32;
-        else
-                return -EINVAL;
-
         /* per-word shift register access, in hardware or bitbanging */
         cs->txrx_word = bitbang->txrx_word[spi->mode & (SPI_CPOL|SPI_CPHA)];
         if (!cs->txrx_word)
                 return -EINVAL;
 
-        /* nsecs = (clock period)/2 */
-        cs->nsecs = (1000000000/2) / (spi->max_speed_hz);
-        if (cs->nsecs > MAX_UDELAY_MS * 1000)
-                return -EINVAL;
+        retval = bitbang_transfer_setup(spi, NULL);
+        if (retval < 0)
+                return retval;
 
         dev_dbg(&spi->dev, "%s, mode %d, %u bits/w, %u nsec\n",
                         __FUNCTION__, spi->mode & (SPI_CPOL | SPI_CPHA),
@@ -246,6 +273,8 @@ static void bitbang_work(void *_bitbang)
                 unsigned                tmp;
                 unsigned                cs_change;
                 int                     status;
+                int                     (*setup_transfer)(struct spi_device *,
+                                                struct spi_transfer *);
 
                 m = container_of(bitbang->queue.next, struct spi_message,
                                 queue);
@@ -262,6 +291,7 @@ static void bitbang_work(void *_bitbang)
                 tmp = 0;
                 cs_change = 1;
                 status = 0;
+                setup_transfer = NULL;
 
                 list_for_each_entry (t, &m->transfers, transfer_list) {
                         if (bitbang->shutdown) {
@@ -269,6 +299,20 @@ static void bitbang_work(void *_bitbang)
                                 break;
                         }
 
+                        /* override or restore speed and wordsize */
+                        if (t->speed_hz || t->bits_per_word) {
+                                setup_transfer = bitbang->setup_transfer;
+                                if (!setup_transfer) {
+                                        status = -ENOPROTOOPT;
+                                        break;
+                                }
+                        }
+                        if (setup_transfer) {
+                                status = setup_transfer(spi, t);
+                                if (status < 0)
+                                        break;
+                        }
+
                         /* set up default clock polarity, and activate chip;
                          * this implicitly updates clock and spi modes as
                          * previously recorded for this device via setup().
@@ -325,6 +369,10 @@ static void bitbang_work(void *_bitbang)
                 m->status = status;
                 m->complete(m->context);
 
+                /* restore speed and wordsize */
+                if (setup_transfer)
+                        setup_transfer(spi, NULL);
+
                 /* normally deactivate chipselect ... unless no error and
                  * cs_change has hinted that the next message will probably
                  * be for this chip too.
@@ -406,6 +454,7 @@ int spi_bitbang_start(struct spi_bitbang *bitbang)
                 bitbang->use_dma = 0;
                 bitbang->txrx_bufs = spi_bitbang_bufs;
                 if (!bitbang->master->setup) {
+                        bitbang->setup_transfer = bitbang_transfer_setup;
                         bitbang->master->setup = spi_bitbang_setup;
                         bitbang->master->cleanup = spi_bitbang_cleanup;
                 }
diff --git a/include/linux/spi/spi.h b/include/linux/spi/spi.h
index b05f1463a267..caa4665e3fa2 100644
--- a/include/linux/spi/spi.h
+++ b/include/linux/spi/spi.h
@@ -31,6 +31,7 @@ extern struct bus_type spi_bus_type;
  * @master: SPI controller used with the device.
  * @max_speed_hz: Maximum clock rate to be used with this chip
  *      (on this board); may be changed by the device's driver.
+ *      The spi_transfer.speed_hz can override this for each transfer.
  * @chip-select: Chipselect, distinguishing chips handled by "master".
  * @mode: The spi mode defines how data is clocked out and in.
  *      This may be changed by the device's driver.
@@ -38,6 +39,7 @@ extern struct bus_type spi_bus_type;
  *      like eight or 12 bits are common.  In-memory wordsizes are
  *      powers of two bytes (e.g. 20 bit samples use 32 bits).
  *      This may be changed by the device's driver.
+ *      The spi_transfer.bits_per_word can override this for each transfer.
  * @irq: Negative, or the number passed to request_irq() to receive
  *      interrupts from this device.
  * @controller_state: Controller's runtime state
@@ -268,6 +270,10 @@ extern struct spi_master *spi_busnum_to_master(u16 busnum);
  * @tx_dma: DMA address of tx_buf, if spi_message.is_dma_mapped
  * @rx_dma: DMA address of rx_buf, if spi_message.is_dma_mapped
  * @len: size of rx and tx buffers (in bytes)
+ * @speed_hz: Select a speed other then the device default for this
+ *      transfer. If 0 the default (from spi_device) is used.
+ * @bits_per_word: select a bits_per_word other then the device default
+ *      for this transfer. If 0 the default (from spi_device) is used.
  * @cs_change: affects chipselect after this transfer completes
  * @delay_usecs: microseconds to delay after this transfer before
  *      (optionally) changing the chipselect status, then starting
@@ -322,7 +328,9 @@ struct spi_transfer {
         dma_addr_t      rx_dma;
 
         unsigned        cs_change:1;
+        u8              bits_per_word;
         u16             delay_usecs;
+        u32             speed_hz;
 
         struct list_head transfer_list;
 };
diff --git a/include/linux/spi/spi_bitbang.h b/include/linux/spi/spi_bitbang.h
index c961fe9bf3eb..c954557b757c 100644
--- a/include/linux/spi/spi_bitbang.h
+++ b/include/linux/spi/spi_bitbang.h
@@ -30,6 +30,12 @@ struct spi_bitbang {
 
         struct spi_master       *master;
 
+        /* setup_transfer() changes clock and/or wordsize to match settings
+         * for this transfer; zeroes restore defaults from spi_device.
+         */
+        int     (*setup_transfer)(struct spi_device *spi,
+                        struct spi_transfer *t);
+
         void    (*chipselect)(struct spi_device *spi, int is_on);
 #define BITBANG_CS_ACTIVE       1       /* normally nCS, active low */
 #define BITBANG_CS_INACTIVE     0