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spi/bitbang: Factor out message transfer from message pump loop
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In order to make it easier to convert to transfer_one_message() lift the
code that does the actual message transfer out of the work function that
implements the message pump. This should have no functional impact, it's
just a simple code motion patch.

Signed-off-by: Mark Brown <[email protected]>
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@broonie
broonie committed Jul 15, 2013
1 parent 874b315 commit 91b3085
Showing 1 changed file with 104 additions and 95 deletions.
199 changes: 104 additions & 95 deletions drivers/spi/spi-bitbang.c
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Original file line number Diff line number Diff line change
Expand Up @@ -255,117 +255,126 @@ static int spi_bitbang_bufs(struct spi_device *spi, struct spi_transfer *t)
* Drivers can provide word-at-a-time i/o primitives, or provide
* transfer-at-a-time ones to leverage dma or fifo hardware.
*/
static void bitbang_work(struct work_struct *work)
static int spi_bitbang_transfer_one(struct spi_device *spi,
struct spi_message *m)
{
struct spi_bitbang *bitbang =
container_of(work, struct spi_bitbang, work);
unsigned long flags;
struct spi_message *m, *_m;
struct spi_bitbang *bitbang;
unsigned nsecs;
struct spi_transfer *t = NULL;
unsigned tmp;
unsigned cs_change;
int status;
int do_setup = -1;

spin_lock_irqsave(&bitbang->lock, flags);
bitbang->busy = 1;
list_for_each_entry_safe(m, _m, &bitbang->queue, queue) {
struct spi_device *spi;
unsigned nsecs;
struct spi_transfer *t = NULL;
unsigned tmp;
unsigned cs_change;
int status;
int do_setup = -1;
bitbang = spi_master_get_devdata(spi->master);

list_del(&m->queue);
spin_unlock_irqrestore(&bitbang->lock, flags);
/* FIXME this is made-up ... the correct value is known to
* word-at-a-time bitbang code, and presumably chipselect()
* should enforce these requirements too?
*/
nsecs = 100;

/* FIXME this is made-up ... the correct value is known to
* word-at-a-time bitbang code, and presumably chipselect()
* should enforce these requirements too?
*/
nsecs = 100;
tmp = 0;
cs_change = 1;
status = 0;

spi = m->spi;
tmp = 0;
cs_change = 1;
status = 0;
list_for_each_entry (t, &m->transfers, transfer_list) {

list_for_each_entry (t, &m->transfers, transfer_list) {

/* override speed or wordsize? */
if (t->speed_hz || t->bits_per_word)
do_setup = 1;

/* init (-1) or override (1) transfer params */
if (do_setup != 0) {
status = bitbang->setup_transfer(spi, t);
if (status < 0)
break;
if (do_setup == -1)
do_setup = 0;
}

/* set up default clock polarity, and activate chip;
* this implicitly updates clock and spi modes as
* previously recorded for this device via setup().
* (and also deselects any other chip that might be
* selected ...)
*/
if (cs_change) {
bitbang->chipselect(spi, BITBANG_CS_ACTIVE);
ndelay(nsecs);
}
cs_change = t->cs_change;
if (!t->tx_buf && !t->rx_buf && t->len) {
status = -EINVAL;
break;
}
/* override speed or wordsize? */
if (t->speed_hz || t->bits_per_word)
do_setup = 1;

/* transfer data. the lower level code handles any
* new dma mappings it needs. our caller always gave
* us dma-safe buffers.
*/
if (t->len) {
/* REVISIT dma API still needs a designated
* DMA_ADDR_INVALID; ~0 might be better.
*/
if (!m->is_dma_mapped)
t->rx_dma = t->tx_dma = 0;
status = bitbang->txrx_bufs(spi, t);
}
if (status > 0)
m->actual_length += status;
if (status != t->len) {
/* always report some kind of error */
if (status >= 0)
status = -EREMOTEIO;
/* init (-1) or override (1) transfer params */
if (do_setup != 0) {
status = bitbang->setup_transfer(spi, t);
if (status < 0)
break;
}
status = 0;

/* protocol tweaks before next transfer */
if (t->delay_usecs)
udelay(t->delay_usecs);

if (cs_change && !list_is_last(&t->transfer_list, &m->transfers)) {
/* sometimes a short mid-message deselect of the chip
* may be needed to terminate a mode or command
*/
ndelay(nsecs);
bitbang->chipselect(spi, BITBANG_CS_INACTIVE);
ndelay(nsecs);
}
if (do_setup == -1)
do_setup = 0;
}

m->status = status;
m->complete(m->context);
/* set up default clock polarity, and activate chip;
* this implicitly updates clock and spi modes as
* previously recorded for this device via setup().
* (and also deselects any other chip that might be
* selected ...)
*/
if (cs_change) {
bitbang->chipselect(spi, BITBANG_CS_ACTIVE);
ndelay(nsecs);
}
cs_change = t->cs_change;
if (!t->tx_buf && !t->rx_buf && t->len) {
status = -EINVAL;
break;
}

/* normally deactivate chipselect ... unless no error and
* cs_change has hinted that the next message will probably
* be for this chip too.
/* transfer data. the lower level code handles any
* new dma mappings it needs. our caller always gave
* us dma-safe buffers.
*/
if (!(status == 0 && cs_change)) {
if (t->len) {
/* REVISIT dma API still needs a designated
* DMA_ADDR_INVALID; ~0 might be better.
*/
if (!m->is_dma_mapped)
t->rx_dma = t->tx_dma = 0;
status = bitbang->txrx_bufs(spi, t);
}
if (status > 0)
m->actual_length += status;
if (status != t->len) {
/* always report some kind of error */
if (status >= 0)
status = -EREMOTEIO;
break;
}
status = 0;

/* protocol tweaks before next transfer */
if (t->delay_usecs)
udelay(t->delay_usecs);

if (cs_change && !list_is_last(&t->transfer_list, &m->transfers)) {
/* sometimes a short mid-message deselect of the chip
* may be needed to terminate a mode or command
*/
ndelay(nsecs);
bitbang->chipselect(spi, BITBANG_CS_INACTIVE);
ndelay(nsecs);
}
}

m->status = status;
m->complete(m->context);

/* normally deactivate chipselect ... unless no error and
* cs_change has hinted that the next message will probably
* be for this chip too.
*/
if (!(status == 0 && cs_change)) {
ndelay(nsecs);
bitbang->chipselect(spi, BITBANG_CS_INACTIVE);
ndelay(nsecs);
}

return status;
}

static void bitbang_work(struct work_struct *work)
{
struct spi_bitbang *bitbang =
container_of(work, struct spi_bitbang, work);
unsigned long flags;
struct spi_message *m, *_m;

spin_lock_irqsave(&bitbang->lock, flags);
bitbang->busy = 1;
list_for_each_entry_safe(m, _m, &bitbang->queue, queue) {
list_del(&m->queue);
spin_unlock_irqrestore(&bitbang->lock, flags);

spi_bitbang_transfer_one(m->spi, m);

spin_lock_irqsave(&bitbang->lock, flags);
}
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