diff options
Diffstat (limited to 'drivers/spi/spi_bitbang.c')
| -rw-r--r-- | drivers/spi/spi_bitbang.c | 77 |
1 files changed, 63 insertions, 14 deletions
diff --git a/drivers/spi/spi_bitbang.c b/drivers/spi/spi_bitbang.c index f037e559326..0525c99118c 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; } |