1 files changed, 84 insertions, 20 deletions

diff --git a/drivers/spi/spi_bitbang.c b/drivers/spi/spi_bitbang.c
index f037e5593269..dd2f950b21a7 100644
--- a/drivers/spi/spi_bitbang.c
+++ b/drivers/spi/spi_bitbang.c
@@ -138,6 +138,45 @@ static unsigned bitbang_txrx_32(
         return t->len - count;
 }
 
+int spi_bitbang_setup_transfer(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;
+        if (hz) {
+                cs->nsecs = (1000000000/2) / hz;
+                if (cs->nsecs > (MAX_UDELAY_MS * 1000 * 1000))
+                        return -EINVAL;
+        }
+
+        return 0;
+}
+EXPORT_SYMBOL_GPL(spi_bitbang_setup_transfer);
+
 /**
  * spi_bitbang_setup - default setup for per-word I/O loops
  */
@@ -145,8 +184,16 @@ 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)
+        bitbang = spi_master_get_devdata(spi->master);
+
+        /* REVISIT: some systems will want to support devices using lsb-first
+         * bit encodings on the wire.  In pure software that would be trivial,
+         * just bitbang_txrx_le_cphaX() routines shifting the other way, and
+         * some hardware controllers also have this support.
+         */
+        if ((spi->mode & SPI_LSB_FIRST) != 0)
                 return -EINVAL;
 
         if (!cs) {
@@ -155,32 +202,20 @@ int spi_bitbang_setup(struct spi_device *spi)
                         return -ENOMEM;
                 spi->controller_state = cs;
         }
-        bitbang = spi_master_get_devdata(spi->master);
 
         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 = spi_bitbang_setup_transfer(spi, NULL);
+        if (retval < 0)
+                return retval;
 
-        dev_dbg(&spi->dev, "%s, mode %d, %u bits/w, %u nsec\n",
+        dev_dbg(&spi->dev, "%s, mode %d, %u bits/w, %u nsec/bit\n",
                         __FUNCTION__, spi->mode & (SPI_CPOL | SPI_CPHA),
                         spi->bits_per_word, 2 * cs->nsecs);
 
@@ -246,6 +281,8 @@ 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 +299,7 @@ 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 +307,20 @@ 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 +377,10 @@ 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.
@@ -348,6 +404,7 @@ int spi_bitbang_transfer(struct spi_device *spi, struct spi_message *m)
 {
         struct spi_bitbang      *bitbang;
         unsigned long           flags;
+        int                     status = 0;
 
         m->actual_length = 0;
         m->status = -EINPROGRESS;
@@ -357,11 +414,15 @@ int spi_bitbang_transfer(struct spi_device *spi, struct spi_message *m)
                 return -ESHUTDOWN;
 
         spin_lock_irqsave(&bitbang->lock, flags);
-        list_add_tail(&m->queue, &bitbang->queue);
-        queue_work(bitbang->workqueue, &bitbang->work);
+        if (!spi->max_speed_hz)
+                status = -ENETDOWN;
+        else {
+                list_add_tail(&m->queue, &bitbang->queue);
+                queue_work(bitbang->workqueue, &bitbang->work);
+        }
         spin_unlock_irqrestore(&bitbang->lock, flags);
 
-        return 0;
+        return status;
 }
 EXPORT_SYMBOL_GPL(spi_bitbang_transfer);
 
@@ -406,6 +467,9 @@ int spi_bitbang_start(struct spi_bitbang *bitbang)
                 bitbang->use_dma = 0;
                 bitbang->txrx_bufs = spi_bitbang_bufs;
                 if (!bitbang->master->setup) {
+                        if (!bitbang->setup_transfer)
+                                bitbang->setup_transfer =
+                                         spi_bitbang_setup_transfer;
                         bitbang->master->setup = spi_bitbang_setup;
                         bitbang->master->cleanup = spi_bitbang_cleanup;
                 }