forked from Minki/linux
spi/bcm63xx: work around inability to keep CS up
This SPI controller does not support keeping CS asserted after sending a transfer. Since messages expected on this SPI controller are rather short, we can work around it for normal use cases by sending all transfers at once in a big full duplex stream. This means that we cannot change the speed between transfers if they require CS to be kept asserted, but these would have been rejected before anyway because of the inability of keeping CS asserted. Signed-off-by: Jonas Gorski <jogo@openwrt.org> Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
This commit is contained in:
Jonas Gorski
Grant Likely
parent
32310aaf5c
commit
b17de07606
@ -37,6 +37,8 @@
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#define PFX KBUILD_MODNAME
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#define BCM63XX_SPI_MAX_PREPEND 15
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struct bcm63xx_spi {
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struct completion done;
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@ -169,13 +171,17 @@ static int bcm63xx_spi_setup(struct spi_device *spi)
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return 0;
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}
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static int bcm63xx_txrx_bufs(struct spi_device *spi, struct spi_transfer *t)
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static int bcm63xx_txrx_bufs(struct spi_device *spi, struct spi_transfer *first,
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unsigned int num_transfers)
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{
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struct bcm63xx_spi *bs = spi_master_get_devdata(spi->master);
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u16 msg_ctl;
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u16 cmd;
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u8 rx_tail;
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unsigned int timeout = 0;
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unsigned int i, timeout = 0, prepend_len = 0, len = 0;
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struct spi_transfer *t = first;
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bool do_rx = false;
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bool do_tx = false;
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/* Disable the CMD_DONE interrupt */
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bcm_spi_writeb(bs, 0, SPI_INT_MASK);
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@ -183,19 +189,45 @@ static int bcm63xx_txrx_bufs(struct spi_device *spi, struct spi_transfer *t)
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dev_dbg(&spi->dev, "txrx: tx %p, rx %p, len %d\n",
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t->tx_buf, t->rx_buf, t->len);
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if (t->tx_buf)
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memcpy_toio(bs->tx_io, t->tx_buf, t->len);
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if (num_transfers > 1 && t->tx_buf && t->len <= BCM63XX_SPI_MAX_PREPEND)
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prepend_len = t->len;
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/* prepare the buffer */
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for (i = 0; i < num_transfers; i++) {
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if (t->tx_buf) {
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do_tx = true;
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memcpy_toio(bs->tx_io + len, t->tx_buf, t->len);
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/* don't prepend more than one tx */
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if (t != first)
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prepend_len = 0;
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}
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if (t->rx_buf) {
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do_rx = true;
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/* prepend is half-duplex write only */
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if (t == first)
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prepend_len = 0;
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}
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len += t->len;
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t = list_entry(t->transfer_list.next, struct spi_transfer,
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transfer_list);
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}
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len -= prepend_len;
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init_completion(&bs->done);
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/* Fill in the Message control register */
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msg_ctl = (t->len << SPI_BYTE_CNT_SHIFT);
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msg_ctl = (len << SPI_BYTE_CNT_SHIFT);
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if (t->rx_buf && t->tx_buf)
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if (do_rx && do_tx && prepend_len == 0)
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msg_ctl |= (SPI_FD_RW << bs->msg_type_shift);
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else if (t->rx_buf)
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else if (do_rx)
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msg_ctl |= (SPI_HD_R << bs->msg_type_shift);
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else if (t->tx_buf)
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else if (do_tx)
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msg_ctl |= (SPI_HD_W << bs->msg_type_shift);
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switch (bs->msg_ctl_width) {
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@ -209,7 +241,7 @@ static int bcm63xx_txrx_bufs(struct spi_device *spi, struct spi_transfer *t)
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/* Issue the transfer */
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cmd = SPI_CMD_START_IMMEDIATE;
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cmd |= (0 << SPI_CMD_PREPEND_BYTE_CNT_SHIFT);
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cmd |= (prepend_len << SPI_CMD_PREPEND_BYTE_CNT_SHIFT);
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cmd |= (spi->chip_select << SPI_CMD_DEVICE_ID_SHIFT);
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bcm_spi_writew(bs, cmd, SPI_CMD);
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@ -223,9 +255,25 @@ static int bcm63xx_txrx_bufs(struct spi_device *spi, struct spi_transfer *t)
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/* read out all data */
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rx_tail = bcm_spi_readb(bs, SPI_RX_TAIL);
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if (do_rx && rx_tail != len)
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return -EIO;
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if (!rx_tail)
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return 0;
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len = 0;
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t = first;
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/* Read out all the data */
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if (rx_tail)
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memcpy_fromio(t->rx_ptr, bs->rx_io, rx_tail);
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for (i = 0; i < num_transfers; i++) {
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if (t->rx_buf)
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memcpy_fromio(t->rx_buf, bs->rx_io + len, t->len);
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if (t != first || prepend_len == 0)
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len += t->len;
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t = list_entry(t->transfer_list.next, struct spi_transfer,
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transfer_list);
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}
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return 0;
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}
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@ -252,19 +300,48 @@ static int bcm63xx_spi_transfer_one(struct spi_master *master,
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struct spi_message *m)
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{
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struct bcm63xx_spi *bs = spi_master_get_devdata(master);
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struct spi_transfer *t;
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struct spi_transfer *t, *first = NULL;
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struct spi_device *spi = m->spi;
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int status = 0;
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unsigned int n_transfers = 0, total_len = 0;
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bool can_use_prepend = false;
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/*
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* This SPI controller does not support keeping CS active after a
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* transfer.
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* Work around this by merging as many transfers we can into one big
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* full-duplex transfers.
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*/
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list_for_each_entry(t, &m->transfers, transfer_list) {
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status = bcm63xx_spi_check_transfer(spi, t);
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if (status < 0)
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goto exit;
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if (!first)
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first = t;
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n_transfers++;
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total_len += t->len;
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if (n_transfers == 2 && !first->rx_buf && !t->tx_buf &&
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first->len <= BCM63XX_SPI_MAX_PREPEND)
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can_use_prepend = true;
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else if (can_use_prepend && t->tx_buf)
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can_use_prepend = false;
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/* we can only transfer one fifo worth of data */
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if (t->len > bs->fifo_size) {
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if ((can_use_prepend &&
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total_len > (bs->fifo_size + BCM63XX_SPI_MAX_PREPEND)) ||
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(!can_use_prepend && total_len > bs->fifo_size)) {
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dev_err(&spi->dev, "unable to do transfers larger than FIFO size (%i > %i)\n",
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t->len, bs->fifo_size);
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total_len, bs->fifo_size);
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status = -EINVAL;
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goto exit;
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}
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/* all combined transfers have to have the same speed */
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if (t->speed_hz != first->speed_hz) {
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dev_err(&spi->dev, "unable to change speed between transfers\n");
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status = -EINVAL;
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goto exit;
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}
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@ -276,22 +353,23 @@ static int bcm63xx_spi_transfer_one(struct spi_master *master,
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goto exit;
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}
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if (!t->cs_change &&
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!list_is_last(&t->transfer_list, &m->transfers)) {
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dev_err(&spi->dev, "unable to keep CS asserted between transfers\n");
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status = -EINVAL;
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goto exit;
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if (t->cs_change ||
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list_is_last(&t->transfer_list, &m->transfers)) {
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/* configure adapter for a new transfer */
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bcm63xx_spi_setup_transfer(spi, first);
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/* send the data */
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status = bcm63xx_txrx_bufs(spi, first, n_transfers);
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if (status)
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goto exit;
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m->actual_length += total_len;
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first = NULL;
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n_transfers = 0;
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total_len = 0;
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can_use_prepend = false;
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}
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/* configure adapter for a new transfer */
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bcm63xx_spi_setup_transfer(spi, t);
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/* send the data */
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status = bcm63xx_txrx_bufs(spi, t);
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if (status)
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goto exit;
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m->actual_length += t->len;
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}
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exit:
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m->status = status;
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