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path: root/drivers/spi/spi_bitbang.c
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Diffstat (limited to 'drivers/spi/spi_bitbang.c')
-rw-r--r--drivers/spi/spi_bitbang.c104
1 files changed, 84 insertions, 20 deletions
diff --git a/drivers/spi/spi_bitbang.c b/drivers/spi/spi_bitbang.c
index f037e559326..dd2f950b21a 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;
}