spi_mpc83xx: much improved driver

The current driver may cause glitches on SPI CLK line since one must disable
the SPI controller before changing any HW settings.  Fix this by implementing
a local spi_transfer function that won't change speed and/or word size while
CS is active.

While doing that heavy lifting a few other issues were addressed too:
 - Make word size 16 and 32 work too.
 - Honor bits_per_word and speed_hz in spi transaction.
 - Optimize the common path.

This also stops using the "bitbang" framework (except for a few constants).

[Roel Kluin <12o3l@tiscali.nl>: "irq" needs to be signed]
Signed-off-by: Joakim Tjernlund <Joakim.Tjernlund@transmode.se>
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2 files changed, 282 insertions, 130 deletions

diff --git a/drivers/spi/Kconfig b/drivers/spi/Kconfig
index fae9e8f3d092..66ec5d8808de 100644
--- a/drivers/spi/Kconfig
+++ b/drivers/spi/Kconfig
@@ -126,7 +126,6 @@ config SPI_MPC52xx_PSC
 config SPI_MPC83xx
         tristate "Freescale MPC83xx/QUICC Engine SPI controller"
         depends on SPI_MASTER && (PPC_83xx || QUICC_ENGINE) && EXPERIMENTAL
-        select SPI_BITBANG
         help
           This enables using the Freescale MPC83xx and QUICC Engine SPI
           controllers in master mode.
diff --git a/drivers/spi/spi_mpc83xx.c b/drivers/spi/spi_mpc83xx.c
index 189f706b9e4b..6832da6f7109 100644
--- a/drivers/spi/spi_mpc83xx.c
+++ b/drivers/spi/spi_mpc83xx.c
@@ -49,6 +49,7 @@ struct mpc83xx_spi_reg {
 #define SPMODE_LEN(x)           ((x) << 20)
 #define SPMODE_PM(x)            ((x) << 16)
 #define SPMODE_OP               (1 << 14)
+#define SPMODE_CG(x)            ((x) << 7)
 
 /*
  * Default for SPI Mode:
@@ -67,10 +68,6 @@ struct mpc83xx_spi_reg {
 
 /* SPI Controller driver's private data. */
 struct mpc83xx_spi {
-        /* bitbang has to be first */
-        struct spi_bitbang bitbang;
-        struct completion done;
-
         struct mpc83xx_spi_reg __iomem *base;
 
         /* rx & tx bufs from the spi_transfer */
@@ -82,7 +79,7 @@ struct mpc83xx_spi {
         u32(*get_tx) (struct mpc83xx_spi *);
 
         unsigned int count;
-        u32 irq;
+        int irq;
 
         unsigned nsecs;         /* (clock cycle time)/2 */
 
@@ -94,6 +91,25 @@ struct mpc83xx_spi {
 
         void (*activate_cs) (u8 cs, u8 polarity);
         void (*deactivate_cs) (u8 cs, u8 polarity);
+
+        u8 busy;
+
+        struct workqueue_struct *workqueue;
+        struct work_struct work;
+
+        struct list_head queue;
+        spinlock_t lock;
+
+        struct completion done;
+};
+
+struct spi_mpc83xx_cs {
+        /* functions to deal with different sized buffers */
+        void (*get_rx) (u32 rx_data, struct mpc83xx_spi *);
+        u32 (*get_tx) (struct mpc83xx_spi *);
+        u32 rx_shift;           /* RX data reg shift when in qe mode */
+        u32 tx_shift;           /* TX data reg shift when in qe mode */
+        u32 hw_mode;            /* Holds HW mode register settings */
 };
 
 static inline void mpc83xx_spi_write_reg(__be32 __iomem * reg, u32 val)
@@ -137,6 +153,7 @@ static void mpc83xx_spi_chipselect(struct spi_device *spi, int value)
 {
         struct mpc83xx_spi *mpc83xx_spi;
         u8 pol = spi->mode & SPI_CS_HIGH ? 1 : 0;
+        struct spi_mpc83xx_cs   *cs = spi->controller_state;
 
         mpc83xx_spi = spi_master_get_devdata(spi->master);
 
@@ -147,50 +164,26 @@ static void mpc83xx_spi_chipselect(struct spi_device *spi, int value)
 
         if (value == BITBANG_CS_ACTIVE) {
                 u32 regval = mpc83xx_spi_read_reg(&mpc83xx_spi->base->mode);
-                u32 len = spi->bits_per_word;
-                u8 pm;
 
-                if (len == 32)
-                        len = 0;
-                else
-                        len = len - 1;
-
-                /* mask out bits we are going to set */
-                regval &= ~(SPMODE_CP_BEGIN_EDGECLK | SPMODE_CI_INACTIVEHIGH
-                                | SPMODE_LEN(0xF) | SPMODE_DIV16
-                                | SPMODE_PM(0xF) | SPMODE_REV | SPMODE_LOOP);
-
-                if (spi->mode & SPI_CPHA)
-                        regval |= SPMODE_CP_BEGIN_EDGECLK;
-                if (spi->mode & SPI_CPOL)
-                        regval |= SPMODE_CI_INACTIVEHIGH;
-                if (!(spi->mode & SPI_LSB_FIRST))
-                        regval |= SPMODE_REV;
-                if (spi->mode & SPI_LOOP)
-                        regval |= SPMODE_LOOP;
-
-                regval |= SPMODE_LEN(len);
-
-                if ((mpc83xx_spi->spibrg / spi->max_speed_hz) >= 64) {
-                        pm = mpc83xx_spi->spibrg / (spi->max_speed_hz * 64) - 1;
-                        if (pm > 0x0f) {
-                                dev_err(&spi->dev, "Requested speed is too "
-                                        "low: %d Hz. Will use %d Hz instead.\n",
-                                        spi->max_speed_hz,
-                                        mpc83xx_spi->spibrg / 1024);
-                                pm = 0x0f;
-                        }
-                        regval |= SPMODE_PM(pm) | SPMODE_DIV16;
-                } else {
-                        pm = mpc83xx_spi->spibrg / (spi->max_speed_hz * 4);
-                        if (pm)
-                                pm--;
-                        regval |= SPMODE_PM(pm);
+                mpc83xx_spi->rx_shift = cs->rx_shift;
+                mpc83xx_spi->tx_shift = cs->tx_shift;
+                mpc83xx_spi->get_rx = cs->get_rx;
+                mpc83xx_spi->get_tx = cs->get_tx;
+
+                if (cs->hw_mode != regval) {
+                        unsigned long flags;
+                        void *tmp_ptr = &mpc83xx_spi->base->mode;
+
+                        regval = cs->hw_mode;
+                        /* Turn off IRQs locally to minimize time that
+                         * SPI is disabled
+                         */
+                        local_irq_save(flags);
+                        /* Turn off SPI unit prior changing mode */
+                        mpc83xx_spi_write_reg(tmp_ptr, regval & ~SPMODE_ENABLE);
+                        mpc83xx_spi_write_reg(tmp_ptr, regval);
+                        local_irq_restore(flags);
                 }
-
-                /* Turn off SPI unit prior changing mode */
-                mpc83xx_spi_write_reg(&mpc83xx_spi->base->mode, 0);
-                mpc83xx_spi_write_reg(&mpc83xx_spi->base->mode, regval);
                 if (mpc83xx_spi->activate_cs)
                         mpc83xx_spi->activate_cs(spi->chip_select, pol);
         }
@@ -201,8 +194,9 @@ int mpc83xx_spi_setup_transfer(struct spi_device *spi, struct spi_transfer *t)
 {
         struct mpc83xx_spi *mpc83xx_spi;
         u32 regval;
-        u8 bits_per_word;
+        u8 bits_per_word, pm;
         u32 hz;
+        struct spi_mpc83xx_cs   *cs = spi->controller_state;
 
         mpc83xx_spi = spi_master_get_devdata(spi->master);
 
@@ -223,61 +217,191 @@ int mpc83xx_spi_setup_transfer(struct spi_device *spi, struct spi_transfer *t)
             || ((bits_per_word > 16) && (bits_per_word != 32)))
                 return -EINVAL;
 
-        mpc83xx_spi->rx_shift = 0;
-        mpc83xx_spi->tx_shift = 0;
+        if (!hz)
+                hz = spi->max_speed_hz;
+
+        cs->rx_shift = 0;
+        cs->tx_shift = 0;
         if (bits_per_word <= 8) {
-                mpc83xx_spi->get_rx = mpc83xx_spi_rx_buf_u8;
-                mpc83xx_spi->get_tx = mpc83xx_spi_tx_buf_u8;
+                cs->get_rx = mpc83xx_spi_rx_buf_u8;
+                cs->get_tx = mpc83xx_spi_tx_buf_u8;
                 if (mpc83xx_spi->qe_mode) {
-                        mpc83xx_spi->rx_shift = 16;
-                        mpc83xx_spi->tx_shift = 24;
+                        cs->rx_shift = 16;
+                        cs->tx_shift = 24;
                 }
         } else if (bits_per_word <= 16) {
-                mpc83xx_spi->get_rx = mpc83xx_spi_rx_buf_u16;
-                mpc83xx_spi->get_tx = mpc83xx_spi_tx_buf_u16;
+                cs->get_rx = mpc83xx_spi_rx_buf_u16;
+                cs->get_tx = mpc83xx_spi_tx_buf_u16;
                 if (mpc83xx_spi->qe_mode) {
-                        mpc83xx_spi->rx_shift = 16;
-                        mpc83xx_spi->tx_shift = 16;
+                        cs->rx_shift = 16;
+                        cs->tx_shift = 16;
                 }
         } else if (bits_per_word <= 32) {
-                mpc83xx_spi->get_rx = mpc83xx_spi_rx_buf_u32;
-                mpc83xx_spi->get_tx = mpc83xx_spi_tx_buf_u32;
+                cs->get_rx = mpc83xx_spi_rx_buf_u32;
+                cs->get_tx = mpc83xx_spi_tx_buf_u32;
         } else
                 return -EINVAL;
 
         if (mpc83xx_spi->qe_mode && spi->mode & SPI_LSB_FIRST) {
-                mpc83xx_spi->tx_shift = 0;
+                cs->tx_shift = 0;
                 if (bits_per_word <= 8)
-                        mpc83xx_spi->rx_shift = 8;
+                        cs->rx_shift = 8;
                 else
-                        mpc83xx_spi->rx_shift = 0;
+                        cs->rx_shift = 0;
         }
 
-        /* nsecs = (clock period)/2 */
-        if (!hz)
-                hz = spi->max_speed_hz;
-        mpc83xx_spi->nsecs = (1000000000 / 2) / hz;
-        if (mpc83xx_spi->nsecs > MAX_UDELAY_MS * 1000)
-                return -EINVAL;
+        mpc83xx_spi->rx_shift = cs->rx_shift;
+        mpc83xx_spi->tx_shift = cs->tx_shift;
+        mpc83xx_spi->get_rx = cs->get_rx;
+        mpc83xx_spi->get_tx = cs->get_tx;
 
         if (bits_per_word == 32)
                 bits_per_word = 0;
         else
                 bits_per_word = bits_per_word - 1;
 
-        regval = mpc83xx_spi_read_reg(&mpc83xx_spi->base->mode);
-
         /* mask out bits we are going to set */
-        regval &= ~(SPMODE_LEN(0xF) | SPMODE_REV);
-        regval |= SPMODE_LEN(bits_per_word);
-        if (!(spi->mode & SPI_LSB_FIRST))
-                regval |= SPMODE_REV;
+        cs->hw_mode &= ~(SPMODE_LEN(0xF) | SPMODE_DIV16
+                                  | SPMODE_PM(0xF));
+
+        cs->hw_mode |= SPMODE_LEN(bits_per_word);
+
+        if ((mpc83xx_spi->spibrg / hz) >= 64) {
+                pm = mpc83xx_spi->spibrg / (hz * 64) - 1;
+                if (pm > 0x0f) {
+                        dev_err(&spi->dev, "Requested speed is too "
+                                "low: %d Hz. Will use %d Hz instead.\n",
+                                hz, mpc83xx_spi->spibrg / 1024);
+                        pm = 0x0f;
+                }
+                cs->hw_mode |= SPMODE_PM(pm) | SPMODE_DIV16;
+        } else {
+                pm = mpc83xx_spi->spibrg / (hz * 4);
+                if (pm)
+                        pm--;
+                cs->hw_mode |= SPMODE_PM(pm);
+        }
+        regval =  mpc83xx_spi_read_reg(&mpc83xx_spi->base->mode);
+        if (cs->hw_mode != regval) {
+                unsigned long flags;
+                void *tmp_ptr = &mpc83xx_spi->base->mode;
+
+                regval = cs->hw_mode;
+                /* Turn off IRQs locally to minimize time
+                 * that SPI is disabled
+                 */
+                local_irq_save(flags);
+                /* Turn off SPI unit prior changing mode */
+                mpc83xx_spi_write_reg(tmp_ptr, regval & ~SPMODE_ENABLE);
+                mpc83xx_spi_write_reg(tmp_ptr, regval);
+                local_irq_restore(flags);
+        }
+        return 0;
+}
 
-        /* Turn off SPI unit prior changing mode */
-        mpc83xx_spi_write_reg(&mpc83xx_spi->base->mode, 0);
-        mpc83xx_spi_write_reg(&mpc83xx_spi->base->mode, regval);
+static int mpc83xx_spi_bufs(struct spi_device *spi, struct spi_transfer *t)
+{
+        struct mpc83xx_spi *mpc83xx_spi;
+        u32 word, len, bits_per_word;
 
-        return 0;
+        mpc83xx_spi = spi_master_get_devdata(spi->master);
+
+        mpc83xx_spi->tx = t->tx_buf;
+        mpc83xx_spi->rx = t->rx_buf;
+        bits_per_word = spi->bits_per_word;
+        if (t->bits_per_word)
+                bits_per_word = t->bits_per_word;
+        len = t->len;
+        if (bits_per_word > 8)
+                len /= 2;
+        if (bits_per_word > 16)
+                len /= 2;
+        mpc83xx_spi->count = len;
+        INIT_COMPLETION(mpc83xx_spi->done);
+
+        /* enable rx ints */
+        mpc83xx_spi_write_reg(&mpc83xx_spi->base->mask, SPIM_NE);
+
+        /* transmit word */
+        word = mpc83xx_spi->get_tx(mpc83xx_spi);
+        mpc83xx_spi_write_reg(&mpc83xx_spi->base->transmit, word);
+
+        wait_for_completion(&mpc83xx_spi->done);
+
+        /* disable rx ints */
+        mpc83xx_spi_write_reg(&mpc83xx_spi->base->mask, 0);
+
+        return mpc83xx_spi->count;
+}
+
+static void mpc83xx_spi_work(struct work_struct *work)
+{
+        struct mpc83xx_spi *mpc83xx_spi =
+                container_of(work, struct mpc83xx_spi, work);
+
+        spin_lock_irq(&mpc83xx_spi->lock);
+        mpc83xx_spi->busy = 1;
+        while (!list_empty(&mpc83xx_spi->queue)) {
+                struct spi_message *m;
+                struct spi_device *spi;
+                struct spi_transfer *t = NULL;
+                unsigned cs_change;
+                int status, nsecs = 50;
+
+                m = container_of(mpc83xx_spi->queue.next,
+                                struct spi_message, queue);
+                list_del_init(&m->queue);
+                spin_unlock_irq(&mpc83xx_spi->lock);
+
+                spi = m->spi;
+                cs_change = 1;
+                status = 0;
+                list_for_each_entry(t, &m->transfers, transfer_list) {
+                        if (t->bits_per_word || t->speed_hz) {
+                                /* Don't allow changes if CS is active */
+                                status = -EINVAL;
+
+                                if (cs_change)
+                                        status = mpc83xx_spi_setup_transfer(spi, t);
+                                if (status < 0)
+                                        break;
+                        }
+
+                        if (cs_change)
+                                mpc83xx_spi_chipselect(spi, BITBANG_CS_ACTIVE);
+                        cs_change = t->cs_change;
+                        if (t->len)
+                                status = mpc83xx_spi_bufs(spi, t);
+                        if (status) {
+                                status = -EMSGSIZE;
+                                break;
+                        }
+                        m->actual_length += t->len;
+
+                        if (t->delay_usecs)
+                                udelay(t->delay_usecs);
+
+                        if (cs_change) {
+                                ndelay(nsecs);
+                                mpc83xx_spi_chipselect(spi, BITBANG_CS_INACTIVE);
+                                ndelay(nsecs);
+                        }
+                }
+
+                m->status = status;
+                m->complete(m->context);
+
+                if (status || !cs_change) {
+                        ndelay(nsecs);
+                        mpc83xx_spi_chipselect(spi, BITBANG_CS_INACTIVE);
+                }
+
+                mpc83xx_spi_setup_transfer(spi, NULL);
+
+                spin_lock_irq(&mpc83xx_spi->lock);
+        }
+        mpc83xx_spi->busy = 0;
+        spin_unlock_irq(&mpc83xx_spi->lock);
 }
 
 /* the spi->mode bits understood by this driver: */
@@ -286,9 +410,10 @@ int mpc83xx_spi_setup_transfer(struct spi_device *spi, struct spi_transfer *t)
 
 static int mpc83xx_spi_setup(struct spi_device *spi)
 {
-        struct spi_bitbang *bitbang;
         struct mpc83xx_spi *mpc83xx_spi;
         int retval;
+        u32 hw_mode;
+        struct spi_mpc83xx_cs   *cs = spi->controller_state;
 
         if (spi->mode & ~MODEBITS) {
                 dev_dbg(&spi->dev, "setup: unsupported mode bits %x\n",
@@ -299,63 +424,56 @@ static int mpc83xx_spi_setup(struct spi_device *spi)
         if (!spi->max_speed_hz)
                 return -EINVAL;
 
-        bitbang = spi_master_get_devdata(spi->master);
+        if (!cs) {
+                cs = kzalloc(sizeof *cs, GFP_KERNEL);
+                if (!cs)
+                        return -ENOMEM;
+                spi->controller_state = cs;
+        }
         mpc83xx_spi = spi_master_get_devdata(spi->master);
 
         if (!spi->bits_per_word)
                 spi->bits_per_word = 8;
 
+        hw_mode = cs->hw_mode; /* Save orginal settings */
+        cs->hw_mode = mpc83xx_spi_read_reg(&mpc83xx_spi->base->mode);
+        /* mask out bits we are going to set */
+        cs->hw_mode &= ~(SPMODE_CP_BEGIN_EDGECLK | SPMODE_CI_INACTIVEHIGH
+                         | SPMODE_REV | SPMODE_LOOP);
+
+        if (spi->mode & SPI_CPHA)
+                cs->hw_mode |= SPMODE_CP_BEGIN_EDGECLK;
+        if (spi->mode & SPI_CPOL)
+                cs->hw_mode |= SPMODE_CI_INACTIVEHIGH;
+        if (!(spi->mode & SPI_LSB_FIRST))
+                cs->hw_mode |= SPMODE_REV;
+        if (spi->mode & SPI_LOOP)
+                cs->hw_mode |= SPMODE_LOOP;
+
         retval = mpc83xx_spi_setup_transfer(spi, NULL);
-        if (retval < 0)
+        if (retval < 0) {
+                cs->hw_mode = hw_mode; /* Restore settings */
                 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 Hz\n",
                 __func__, spi->mode & (SPI_CPOL | SPI_CPHA),
-                spi->bits_per_word, 2 * mpc83xx_spi->nsecs);
-
+                spi->bits_per_word, spi->max_speed_hz);
+#if 0 /* Don't think this is needed */
         /* NOTE we _need_ to call chipselect() early, ideally with adapter
          * setup, unless the hardware defaults cooperate to avoid confusion
          * between normal (active low) and inverted chipselects.
          */
 
         /* deselect chip (low or high) */
-        spin_lock(&bitbang->lock);
-        if (!bitbang->busy) {
-                bitbang->chipselect(spi, BITBANG_CS_INACTIVE);
-                ndelay(mpc83xx_spi->nsecs);
-        }
-        spin_unlock(&bitbang->lock);
-
+        spin_lock(&mpc83xx_spi->lock);
+        if (!mpc83xx_spi->busy)
+                mpc83xx_spi_chipselect(spi, BITBANG_CS_INACTIVE);
+        spin_unlock(&mpc83xx_spi->lock);
+#endif
         return 0;
 }
 
-static int mpc83xx_spi_bufs(struct spi_device *spi, struct spi_transfer *t)
-{
-        struct mpc83xx_spi *mpc83xx_spi;
-        u32 word;
-
-        mpc83xx_spi = spi_master_get_devdata(spi->master);
-
-        mpc83xx_spi->tx = t->tx_buf;
-        mpc83xx_spi->rx = t->rx_buf;
-        mpc83xx_spi->count = t->len;
-        INIT_COMPLETION(mpc83xx_spi->done);
-
-        /* enable rx ints */
-        mpc83xx_spi_write_reg(&mpc83xx_spi->base->mask, SPIM_NE);
-
-        /* transmit word */
-        word = mpc83xx_spi->get_tx(mpc83xx_spi);
-        mpc83xx_spi_write_reg(&mpc83xx_spi->base->transmit, word);
-
-        wait_for_completion(&mpc83xx_spi->done);
-
-        /* disable rx ints */
-        mpc83xx_spi_write_reg(&mpc83xx_spi->base->mask, 0);
-
-        return t->len - mpc83xx_spi->count;
-}
-
 irqreturn_t mpc83xx_spi_irq(s32 irq, void *context_data)
 {
         struct mpc83xx_spi *mpc83xx_spi = context_data;
@@ -395,6 +513,28 @@ irqreturn_t mpc83xx_spi_irq(s32 irq, void *context_data)
 
         return ret;
 }
+static int mpc83xx_spi_transfer(struct spi_device *spi,
+                                struct spi_message *m)
+{
+        struct mpc83xx_spi *mpc83xx_spi = spi_master_get_devdata(spi->master);
+        unsigned long flags;
+
+        m->actual_length = 0;
+        m->status = -EINPROGRESS;
+
+        spin_lock_irqsave(&mpc83xx_spi->lock, flags);
+        list_add_tail(&m->queue, &mpc83xx_spi->queue);
+        queue_work(mpc83xx_spi->workqueue, &mpc83xx_spi->work);
+        spin_unlock_irqrestore(&mpc83xx_spi->lock, flags);
+
+        return 0;
+}
+
+
+static void mpc83xx_spi_cleanup(struct spi_device *spi)
+{
+        kfree(spi->controller_state);
+}
 
 static int __init mpc83xx_spi_probe(struct platform_device *dev)
 {
@@ -426,11 +566,11 @@ static int __init mpc83xx_spi_probe(struct platform_device *dev)
                 ret = -ENODEV;
                 goto free_master;
         }
+        master->setup = mpc83xx_spi_setup;
+        master->transfer = mpc83xx_spi_transfer;
+        master->cleanup = mpc83xx_spi_cleanup;
+
         mpc83xx_spi = spi_master_get_devdata(master);
-        mpc83xx_spi->bitbang.master = spi_master_get(master);
-        mpc83xx_spi->bitbang.chipselect = mpc83xx_spi_chipselect;
-        mpc83xx_spi->bitbang.setup_transfer = mpc83xx_spi_setup_transfer;
-        mpc83xx_spi->bitbang.txrx_bufs = mpc83xx_spi_bufs;
         mpc83xx_spi->activate_cs = pdata->activate_cs;
         mpc83xx_spi->deactivate_cs = pdata->deactivate_cs;
         mpc83xx_spi->qe_mode = pdata->qe_mode;
@@ -445,7 +585,6 @@ static int __init mpc83xx_spi_probe(struct platform_device *dev)
                 mpc83xx_spi->tx_shift = 24;
         }
 
-        mpc83xx_spi->bitbang.master->setup = mpc83xx_spi_setup;
         init_completion(&mpc83xx_spi->done);
 
         mpc83xx_spi->base = ioremap(r->start, r->end - r->start + 1);
@@ -483,11 +622,21 @@ static int __init mpc83xx_spi_probe(struct platform_device *dev)
                 regval |= SPMODE_OP;
 
         mpc83xx_spi_write_reg(&mpc83xx_spi->base->mode, regval);
+        spin_lock_init(&mpc83xx_spi->lock);
+        init_completion(&mpc83xx_spi->done);
+        INIT_WORK(&mpc83xx_spi->work, mpc83xx_spi_work);
+        INIT_LIST_HEAD(&mpc83xx_spi->queue);
 
-        ret = spi_bitbang_start(&mpc83xx_spi->bitbang);
-
-        if (ret != 0)
+        mpc83xx_spi->workqueue = create_singlethread_workqueue(
+                master->dev.parent->bus_id);
+        if (mpc83xx_spi->workqueue == NULL) {
+                ret = -EBUSY;
                 goto free_irq;
+        }
+
+        ret = spi_register_master(master);
+        if (ret < 0)
+                goto unreg_master;
 
         printk(KERN_INFO
                "%s: MPC83xx SPI Controller driver at 0x%p (irq = %d)\n",
@@ -495,6 +644,8 @@ static int __init mpc83xx_spi_probe(struct platform_device *dev)
 
         return ret;
 
+unreg_master:
+        destroy_workqueue(mpc83xx_spi->workqueue);
 free_irq:
         free_irq(mpc83xx_spi->irq, mpc83xx_spi);
 unmap_io:
@@ -515,10 +666,12 @@ static int __exit mpc83xx_spi_remove(struct platform_device *dev)
         master = platform_get_drvdata(dev);
         mpc83xx_spi = spi_master_get_devdata(master);
 
-        spi_bitbang_stop(&mpc83xx_spi->bitbang);
+        flush_workqueue(mpc83xx_spi->workqueue);
+        destroy_workqueue(mpc83xx_spi->workqueue);
+        spi_unregister_master(master);
+
         free_irq(mpc83xx_spi->irq, mpc83xx_spi);
         iounmap(mpc83xx_spi->base);
-        spi_master_put(mpc83xx_spi->bitbang.master);
 
         return 0;
 }