diff options
Diffstat (limited to 'drivers/spi')
| -rw-r--r-- | drivers/spi/spi.c | 18 | ||||
| -rw-r--r-- | drivers/spi/spi_bitbang.c | 86 |
2 files changed, 60 insertions, 44 deletions
diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c index 3ecedccdb96..cdb242de901 100644 --- a/drivers/spi/spi.c +++ b/drivers/spi/spi.c @@ -557,6 +557,17 @@ int spi_write_then_read(struct spi_device *spi, if ((n_tx + n_rx) > SPI_BUFSIZ) return -EINVAL; + spi_message_init(&message); + memset(x, 0, sizeof x); + if (n_tx) { + x[0].len = n_tx; + spi_message_add_tail(&x[0], &message); + } + if (n_rx) { + x[1].len = n_rx; + spi_message_add_tail(&x[1], &message); + } + /* ... unless someone else is using the pre-allocated buffer */ if (down_trylock(&lock)) { local_buf = kmalloc(SPI_BUFSIZ, GFP_KERNEL); @@ -565,18 +576,11 @@ int spi_write_then_read(struct spi_device *spi, } else local_buf = buf; - memset(x, 0, sizeof x); - memcpy(local_buf, txbuf, n_tx); x[0].tx_buf = local_buf; - x[0].len = n_tx; - x[1].rx_buf = local_buf + n_tx; - x[1].len = n_rx; /* do the i/o */ - message.transfers = x; - message.n_transfer = ARRAY_SIZE(x); status = spi_sync(spi, &message); if (status == 0) { memcpy(rxbuf, x[1].rx_buf, n_rx); diff --git a/drivers/spi/spi_bitbang.c b/drivers/spi/spi_bitbang.c index 44aff198eb9..f037e559326 100644 --- a/drivers/spi/spi_bitbang.c +++ b/drivers/spi/spi_bitbang.c @@ -146,6 +146,9 @@ int spi_bitbang_setup(struct spi_device *spi) struct spi_bitbang_cs *cs = spi->controller_state; struct spi_bitbang *bitbang; + if (!spi->max_speed_hz) + return -EINVAL; + if (!cs) { cs = kzalloc(sizeof *cs, SLAB_KERNEL); if (!cs) @@ -172,13 +175,8 @@ int spi_bitbang_setup(struct spi_device *spi) if (!cs->txrx_word) return -EINVAL; - if (!spi->max_speed_hz) - spi->max_speed_hz = 500 * 1000; - - /* nsecs = max(50, (clock period)/2), be optimistic */ + /* nsecs = (clock period)/2 */ cs->nsecs = (1000000000/2) / (spi->max_speed_hz); - if (cs->nsecs < 50) - cs->nsecs = 50; if (cs->nsecs > MAX_UDELAY_MS * 1000) return -EINVAL; @@ -194,7 +192,7 @@ int spi_bitbang_setup(struct spi_device *spi) /* deselect chip (low or high) */ spin_lock(&bitbang->lock); if (!bitbang->busy) { - bitbang->chipselect(spi, 0); + bitbang->chipselect(spi, BITBANG_CS_INACTIVE); ndelay(cs->nsecs); } spin_unlock(&bitbang->lock); @@ -244,9 +242,9 @@ static void bitbang_work(void *_bitbang) struct spi_message *m; struct spi_device *spi; unsigned nsecs; - struct spi_transfer *t; + struct spi_transfer *t = NULL; unsigned tmp; - unsigned chipselect; + unsigned cs_change; int status; m = container_of(bitbang->queue.next, struct spi_message, @@ -254,37 +252,49 @@ static void bitbang_work(void *_bitbang) list_del_init(&m->queue); spin_unlock_irqrestore(&bitbang->lock, flags); -// FIXME this is made-up -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; spi = m->spi; - t = m->transfers; tmp = 0; - chipselect = 0; + cs_change = 1; status = 0; - for (;;t++) { + list_for_each_entry (t, &m->transfers, transfer_list) { if (bitbang->shutdown) { status = -ESHUTDOWN; break; } - /* set up default clock polarity, and activate chip */ - if (!chipselect) { - bitbang->chipselect(spi, 1); + /* 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; } - /* transfer data */ + /* transfer data. the lower level code handles any + * new dma mappings it needs. our caller always gave + * us dma-safe buffers. + */ if (t->len) { - /* FIXME if bitbang->use_dma, dma_map_single() - * before the transfer, and dma_unmap_single() - * afterwards, for either or both buffers... + /* 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 != t->len) { @@ -299,29 +309,31 @@ nsecs = 100; if (t->delay_usecs) udelay(t->delay_usecs); - tmp++; - if (tmp >= m->n_transfer) - break; - - chipselect = !t->cs_change; - if (chipselect); + if (!cs_change) continue; + if (t->transfer_list.next == &m->transfers) + break; - bitbang->chipselect(spi, 0); - - /* REVISIT do we want the udelay here instead? */ - msleep(1); + /* 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); } - tmp = m->n_transfer - 1; - tmp = m->transfers[tmp].cs_change; - m->status = status; m->complete(m->context); - ndelay(2 * nsecs); - bitbang->chipselect(spi, status == 0 && tmp); - ndelay(nsecs); + /* 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); + } spin_lock_irqsave(&bitbang->lock, flags); } |