};
/* Deals with DMA transactions */
+
+struct pl011_sgbuf {
+ struct scatterlist sg;
+ char *buf;
+};
+
+struct pl011_dmarx_data {
+ struct dma_chan *chan;
+ struct completion complete;
+ bool use_buf_b;
+ struct pl011_sgbuf sgbuf_a;
+ struct pl011_sgbuf sgbuf_b;
+ dma_cookie_t cookie;
+ bool running;
+};
+
struct pl011_dmatx_data {
struct dma_chan *chan;
struct scatterlist sg;
char type[12];
#ifdef CONFIG_DMA_ENGINE
/* DMA stuff */
- bool using_dma;
+ bool using_tx_dma;
+ bool using_rx_dma;
+ struct pl011_dmarx_data dmarx;
struct pl011_dmatx_data dmatx;
#endif
};
+/*
+ * Reads up to 256 characters from the FIFO or until it's empty and
+ * inserts them into the TTY layer. Returns the number of characters
+ * read from the FIFO.
+ */
+static int pl011_fifo_to_tty(struct uart_amba_port *uap)
+{
+ u16 status, ch;
+ unsigned int flag, max_count = 256;
+ int fifotaken = 0;
+
+ while (max_count--) {
+ status = readw(uap->port.membase + UART01x_FR);
+ if (status & UART01x_FR_RXFE)
+ break;
+
+ /* Take chars from the FIFO and update status */
+ ch = readw(uap->port.membase + UART01x_DR) |
+ UART_DUMMY_DR_RX;
+ flag = TTY_NORMAL;
+ uap->port.icount.rx++;
+ fifotaken++;
+
+ if (unlikely(ch & UART_DR_ERROR)) {
+ if (ch & UART011_DR_BE) {
+ ch &= ~(UART011_DR_FE | UART011_DR_PE);
+ uap->port.icount.brk++;
+ if (uart_handle_break(&uap->port))
+ continue;
+ } else if (ch & UART011_DR_PE)
+ uap->port.icount.parity++;
+ else if (ch & UART011_DR_FE)
+ uap->port.icount.frame++;
+ if (ch & UART011_DR_OE)
+ uap->port.icount.overrun++;
+
+ ch &= uap->port.read_status_mask;
+
+ if (ch & UART011_DR_BE)
+ flag = TTY_BREAK;
+ else if (ch & UART011_DR_PE)
+ flag = TTY_PARITY;
+ else if (ch & UART011_DR_FE)
+ flag = TTY_FRAME;
+ }
+
+ if (uart_handle_sysrq_char(&uap->port, ch & 255))
+ continue;
+
+ uart_insert_char(&uap->port, ch, UART011_DR_OE, ch, flag);
+ }
+
+ return fifotaken;
+}
+
+
/*
* All the DMA operation mode stuff goes inside this ifdef.
* This assumes that you have a generic DMA device interface,
#define PL011_DMA_BUFFER_SIZE PAGE_SIZE
+static int pl011_sgbuf_init(struct dma_chan *chan, struct pl011_sgbuf *sg,
+ enum dma_data_direction dir)
+{
+ sg->buf = kmalloc(PL011_DMA_BUFFER_SIZE, GFP_KERNEL);
+ if (!sg->buf)
+ return -ENOMEM;
+
+ sg_init_one(&sg->sg, sg->buf, PL011_DMA_BUFFER_SIZE);
+
+ if (dma_map_sg(chan->device->dev, &sg->sg, 1, dir) != 1) {
+ kfree(sg->buf);
+ return -EINVAL;
+ }
+ return 0;
+}
+
+static void pl011_sgbuf_free(struct dma_chan *chan, struct pl011_sgbuf *sg,
+ enum dma_data_direction dir)
+{
+ if (sg->buf) {
+ dma_unmap_sg(chan->device->dev, &sg->sg, 1, dir);
+ kfree(sg->buf);
+ }
+}
+
static void pl011_dma_probe_initcall(struct uart_amba_port *uap)
{
/* DMA is the sole user of the platform data right now */
return;
}
- /* Try to acquire a generic DMA engine slave channel */
+ /* Try to acquire a generic DMA engine slave TX channel */
dma_cap_zero(mask);
dma_cap_set(DMA_SLAVE, mask);
dev_info(uap->port.dev, "DMA channel TX %s\n",
dma_chan_name(uap->dmatx.chan));
+
+ /* Optionally make use of an RX channel as well */
+ if (plat->dma_rx_param) {
+ struct dma_slave_config rx_conf = {
+ .src_addr = uap->port.mapbase + UART01x_DR,
+ .src_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE,
+ .direction = DMA_FROM_DEVICE,
+ .src_maxburst = uap->fifosize >> 1,
+ };
+
+ chan = dma_request_channel(mask, plat->dma_filter, plat->dma_rx_param);
+ if (!chan) {
+ dev_err(uap->port.dev, "no RX DMA channel!\n");
+ return;
+ }
+
+ dmaengine_slave_config(chan, &rx_conf);
+ uap->dmarx.chan = chan;
+
+ dev_info(uap->port.dev, "DMA channel RX %s\n",
+ dma_chan_name(uap->dmarx.chan));
+ }
}
#ifndef MODULE
/* TODO: remove the initcall if it has not yet executed */
if (uap->dmatx.chan)
dma_release_channel(uap->dmatx.chan);
+ if (uap->dmarx.chan)
+ dma_release_channel(uap->dmarx.chan);
}
-
/* Forward declare this for the refill routine */
static int pl011_dma_tx_refill(struct uart_amba_port *uap);
*/
static bool pl011_dma_tx_irq(struct uart_amba_port *uap)
{
- if (!uap->using_dma)
+ if (!uap->using_tx_dma)
return false;
/*
{
u16 dmacr;
- if (!uap->using_dma)
+ if (!uap->using_tx_dma)
return false;
if (!uap->port.x_char) {
{
struct uart_amba_port *uap = (struct uart_amba_port *)port;
- if (!uap->using_dma)
+ if (!uap->using_tx_dma)
return;
/* Avoid deadlock with the DMA engine callback */
}
}
+static void pl011_dma_rx_callback(void *data);
+
+static int pl011_dma_rx_trigger_dma(struct uart_amba_port *uap)
+{
+ struct dma_chan *rxchan = uap->dmarx.chan;
+ struct dma_device *dma_dev;
+ struct pl011_dmarx_data *dmarx = &uap->dmarx;
+ struct dma_async_tx_descriptor *desc;
+ struct pl011_sgbuf *sgbuf;
+
+ if (!rxchan)
+ return -EIO;
+
+ /* Start the RX DMA job */
+ sgbuf = uap->dmarx.use_buf_b ?
+ &uap->dmarx.sgbuf_b : &uap->dmarx.sgbuf_a;
+ dma_dev = rxchan->device;
+ desc = rxchan->device->device_prep_slave_sg(rxchan, &sgbuf->sg, 1,
+ DMA_FROM_DEVICE,
+ DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
+ /*
+ * If the DMA engine is busy and cannot prepare a
+ * channel, no big deal, the driver will fall back
+ * to interrupt mode as a result of this error code.
+ */
+ if (!desc) {
+ uap->dmarx.running = false;
+ dmaengine_terminate_all(rxchan);
+ return -EBUSY;
+ }
+
+ /* Some data to go along to the callback */
+ desc->callback = pl011_dma_rx_callback;
+ desc->callback_param = uap;
+ dmarx->cookie = dmaengine_submit(desc);
+ dma_async_issue_pending(rxchan);
+
+ uap->dmacr |= UART011_RXDMAE;
+ writew(uap->dmacr, uap->port.membase + UART011_DMACR);
+ uap->dmarx.running = true;
+
+ uap->im &= ~UART011_RXIM;
+ writew(uap->im, uap->port.membase + UART011_IMSC);
+
+ return 0;
+}
+
+/*
+ * This is called when either the DMA job is complete, or
+ * the FIFO timeout interrupt occurred. This must be called
+ * with the port spinlock uap->port.lock held.
+ */
+static void pl011_dma_rx_chars(struct uart_amba_port *uap,
+ u32 pending, bool use_buf_b,
+ bool readfifo)
+{
+ struct tty_struct *tty = uap->port.state->port.tty;
+ struct pl011_sgbuf *sgbuf = use_buf_b ?
+ &uap->dmarx.sgbuf_b : &uap->dmarx.sgbuf_a;
+ struct device *dev = uap->dmarx.chan->device->dev;
+ int dma_count = 0;
+ u32 fifotaken = 0; /* only used for vdbg() */
+
+ /* Pick everything from the DMA first */
+ if (pending) {
+ /* Sync in buffer */
+ dma_sync_sg_for_cpu(dev, &sgbuf->sg, 1, DMA_FROM_DEVICE);
+
+ /*
+ * First take all chars in the DMA pipe, then look in the FIFO.
+ * Note that tty_insert_flip_buf() tries to take as many chars
+ * as it can.
+ */
+ dma_count = tty_insert_flip_string(uap->port.state->port.tty,
+ sgbuf->buf, pending);
+
+ /* Return buffer to device */
+ dma_sync_sg_for_device(dev, &sgbuf->sg, 1, DMA_FROM_DEVICE);
+
+ uap->port.icount.rx += dma_count;
+ if (dma_count < pending)
+ dev_warn(uap->port.dev,
+ "couldn't insert all characters (TTY is full?)\n");
+ }
+
+ /*
+ * Only continue with trying to read the FIFO if all DMA chars have
+ * been taken first.
+ */
+ if (dma_count == pending && readfifo) {
+ /* Clear any error flags */
+ writew(UART011_OEIS | UART011_BEIS | UART011_PEIS | UART011_FEIS,
+ uap->port.membase + UART011_ICR);
+
+ /*
+ * If we read all the DMA'd characters, and we had an
+ * incomplete buffer, that could be due to an rx error, or
+ * maybe we just timed out. Read any pending chars and check
+ * the error status.
+ *
+ * Error conditions will only occur in the FIFO, these will
+ * trigger an immediate interrupt and stop the DMA job, so we
+ * will always find the error in the FIFO, never in the DMA
+ * buffer.
+ */
+ fifotaken = pl011_fifo_to_tty(uap);
+ }
+
+ spin_unlock(&uap->port.lock);
+ dev_vdbg(uap->port.dev,
+ "Took %d chars from DMA buffer and %d chars from the FIFO\n",
+ dma_count, fifotaken);
+ tty_flip_buffer_push(tty);
+ spin_lock(&uap->port.lock);
+}
+
+static void pl011_dma_rx_irq(struct uart_amba_port *uap)
+{
+ struct pl011_dmarx_data *dmarx = &uap->dmarx;
+ struct dma_chan *rxchan = dmarx->chan;
+ struct pl011_sgbuf *sgbuf = dmarx->use_buf_b ?
+ &dmarx->sgbuf_b : &dmarx->sgbuf_a;
+ size_t pending;
+ struct dma_tx_state state;
+ enum dma_status dmastat;
+
+ /*
+ * Pause the transfer so we can trust the current counter,
+ * do this before we pause the PL011 block, else we may
+ * overflow the FIFO.
+ */
+ if (dmaengine_pause(rxchan))
+ dev_err(uap->port.dev, "unable to pause DMA transfer\n");
+ dmastat = rxchan->device->device_tx_status(rxchan,
+ dmarx->cookie, &state);
+ if (dmastat != DMA_PAUSED)
+ dev_err(uap->port.dev, "unable to pause DMA transfer\n");
+
+ /* Disable RX DMA - incoming data will wait in the FIFO */
+ uap->dmacr &= ~UART011_RXDMAE;
+ writew(uap->dmacr, uap->port.membase + UART011_DMACR);
+ uap->dmarx.running = false;
+
+ pending = sgbuf->sg.length - state.residue;
+ BUG_ON(pending > PL011_DMA_BUFFER_SIZE);
+ /* Then we terminate the transfer - we now know our residue */
+ dmaengine_terminate_all(rxchan);
+
+ /*
+ * This will take the chars we have so far and insert
+ * into the framework.
+ */
+ pl011_dma_rx_chars(uap, pending, dmarx->use_buf_b, true);
+
+ /* Switch buffer & re-trigger DMA job */
+ dmarx->use_buf_b = !dmarx->use_buf_b;
+ if (pl011_dma_rx_trigger_dma(uap)) {
+ dev_dbg(uap->port.dev, "could not retrigger RX DMA job "
+ "fall back to interrupt mode\n");
+ uap->im |= UART011_RXIM;
+ writew(uap->im, uap->port.membase + UART011_IMSC);
+ }
+}
+
+static void pl011_dma_rx_callback(void *data)
+{
+ struct uart_amba_port *uap = data;
+ struct pl011_dmarx_data *dmarx = &uap->dmarx;
+ bool lastbuf = dmarx->use_buf_b;
+ int ret;
+
+ /*
+ * This completion interrupt occurs typically when the
+ * RX buffer is totally stuffed but no timeout has yet
+ * occurred. When that happens, we just want the RX
+ * routine to flush out the secondary DMA buffer while
+ * we immediately trigger the next DMA job.
+ */
+ spin_lock_irq(&uap->port.lock);
+ uap->dmarx.running = false;
+ dmarx->use_buf_b = !lastbuf;
+ ret = pl011_dma_rx_trigger_dma(uap);
+
+ pl011_dma_rx_chars(uap, PL011_DMA_BUFFER_SIZE, lastbuf, false);
+ spin_unlock_irq(&uap->port.lock);
+ /*
+ * Do this check after we picked the DMA chars so we don't
+ * get some IRQ immediately from RX.
+ */
+ if (ret) {
+ dev_dbg(uap->port.dev, "could not retrigger RX DMA job "
+ "fall back to interrupt mode\n");
+ uap->im |= UART011_RXIM;
+ writew(uap->im, uap->port.membase + UART011_IMSC);
+ }
+}
+
+/*
+ * Stop accepting received characters, when we're shutting down or
+ * suspending this port.
+ * Locking: called with port lock held and IRQs disabled.
+ */
+static inline void pl011_dma_rx_stop(struct uart_amba_port *uap)
+{
+ /* FIXME. Just disable the DMA enable */
+ uap->dmacr &= ~UART011_RXDMAE;
+ writew(uap->dmacr, uap->port.membase + UART011_DMACR);
+}
static void pl011_dma_startup(struct uart_amba_port *uap)
{
+ int ret;
+
if (!uap->dmatx.chan)
return;
/* The DMA buffer is now the FIFO the TTY subsystem can use */
uap->port.fifosize = PL011_DMA_BUFFER_SIZE;
- uap->using_dma = true;
+ uap->using_tx_dma = true;
+
+ if (!uap->dmarx.chan)
+ goto skip_rx;
+
+ /* Allocate and map DMA RX buffers */
+ ret = pl011_sgbuf_init(uap->dmarx.chan, &uap->dmarx.sgbuf_a,
+ DMA_FROM_DEVICE);
+ if (ret) {
+ dev_err(uap->port.dev, "failed to init DMA %s: %d\n",
+ "RX buffer A", ret);
+ goto skip_rx;
+ }
+
+ ret = pl011_sgbuf_init(uap->dmarx.chan, &uap->dmarx.sgbuf_b,
+ DMA_FROM_DEVICE);
+ if (ret) {
+ dev_err(uap->port.dev, "failed to init DMA %s: %d\n",
+ "RX buffer B", ret);
+ pl011_sgbuf_free(uap->dmarx.chan, &uap->dmarx.sgbuf_a,
+ DMA_FROM_DEVICE);
+ goto skip_rx;
+ }
+ uap->using_rx_dma = true;
+
+skip_rx:
/* Turn on DMA error (RX/TX will be enabled on demand) */
uap->dmacr |= UART011_DMAONERR;
writew(uap->dmacr, uap->port.membase + UART011_DMACR);
if (uap->vendor->dma_threshold)
writew(ST_UART011_DMAWM_RX_16 | ST_UART011_DMAWM_TX_16,
uap->port.membase + ST_UART011_DMAWM);
+
+ if (uap->using_rx_dma) {
+ if (pl011_dma_rx_trigger_dma(uap))
+ dev_dbg(uap->port.dev, "could not trigger initial "
+ "RX DMA job, fall back to interrupt mode\n");
+ }
}
static void pl011_dma_shutdown(struct uart_amba_port *uap)
{
- if (!uap->using_dma)
+ if (!(uap->using_tx_dma || uap->using_rx_dma))
return;
/* Disable RX and TX DMA */
writew(uap->dmacr, uap->port.membase + UART011_DMACR);
spin_unlock_irq(&uap->port.lock);
- /* In theory, this should already be done by pl011_dma_flush_buffer */
- dmaengine_terminate_all(uap->dmatx.chan);
- if (uap->dmatx.queued) {
- dma_unmap_sg(uap->dmatx.chan->device->dev, &uap->dmatx.sg, 1,
- DMA_TO_DEVICE);
- uap->dmatx.queued = false;
+ if (uap->using_tx_dma) {
+ /* In theory, this should already be done by pl011_dma_flush_buffer */
+ dmaengine_terminate_all(uap->dmatx.chan);
+ if (uap->dmatx.queued) {
+ dma_unmap_sg(uap->dmatx.chan->device->dev, &uap->dmatx.sg, 1,
+ DMA_TO_DEVICE);
+ uap->dmatx.queued = false;
+ }
+
+ kfree(uap->dmatx.buf);
+ uap->using_tx_dma = false;
}
- kfree(uap->dmatx.buf);
+ if (uap->using_rx_dma) {
+ dmaengine_terminate_all(uap->dmarx.chan);
+ /* Clean up the RX DMA */
+ pl011_sgbuf_free(uap->dmarx.chan, &uap->dmarx.sgbuf_a, DMA_FROM_DEVICE);
+ pl011_sgbuf_free(uap->dmarx.chan, &uap->dmarx.sgbuf_b, DMA_FROM_DEVICE);
+ uap->using_rx_dma = false;
+ }
+}
- uap->using_dma = false;
+static inline bool pl011_dma_rx_available(struct uart_amba_port *uap)
+{
+ return uap->using_rx_dma;
}
+static inline bool pl011_dma_rx_running(struct uart_amba_port *uap)
+{
+ return uap->using_rx_dma && uap->dmarx.running;
+}
+
+
#else
/* Blank functions if the DMA engine is not available */
static inline void pl011_dma_probe(struct uart_amba_port *uap)
return false;
}
+static inline void pl011_dma_rx_irq(struct uart_amba_port *uap)
+{
+}
+
+static inline void pl011_dma_rx_stop(struct uart_amba_port *uap)
+{
+}
+
+static inline int pl011_dma_rx_trigger_dma(struct uart_amba_port *uap)
+{
+ return -EIO;
+}
+
+static inline bool pl011_dma_rx_available(struct uart_amba_port *uap)
+{
+ return false;
+}
+
+static inline bool pl011_dma_rx_running(struct uart_amba_port *uap)
+{
+ return false;
+}
+
#define pl011_dma_flush_buffer NULL
#endif
uap->im &= ~(UART011_RXIM|UART011_RTIM|UART011_FEIM|
UART011_PEIM|UART011_BEIM|UART011_OEIM);
writew(uap->im, uap->port.membase + UART011_IMSC);
+
+ pl011_dma_rx_stop(uap);
}
static void pl011_enable_ms(struct uart_port *port)
static void pl011_rx_chars(struct uart_amba_port *uap)
{
struct tty_struct *tty = uap->port.state->port.tty;
- unsigned int status, ch, flag, max_count = 256;
-
- status = readw(uap->port.membase + UART01x_FR);
- while ((status & UART01x_FR_RXFE) == 0 && max_count--) {
- ch = readw(uap->port.membase + UART01x_DR) | UART_DUMMY_DR_RX;
- flag = TTY_NORMAL;
- uap->port.icount.rx++;
-
- /*
- * Note that the error handling code is
- * out of the main execution path
- */
- if (unlikely(ch & UART_DR_ERROR)) {
- if (ch & UART011_DR_BE) {
- ch &= ~(UART011_DR_FE | UART011_DR_PE);
- uap->port.icount.brk++;
- if (uart_handle_break(&uap->port))
- goto ignore_char;
- } else if (ch & UART011_DR_PE)
- uap->port.icount.parity++;
- else if (ch & UART011_DR_FE)
- uap->port.icount.frame++;
- if (ch & UART011_DR_OE)
- uap->port.icount.overrun++;
-
- ch &= uap->port.read_status_mask;
-
- if (ch & UART011_DR_BE)
- flag = TTY_BREAK;
- else if (ch & UART011_DR_PE)
- flag = TTY_PARITY;
- else if (ch & UART011_DR_FE)
- flag = TTY_FRAME;
- }
- if (uart_handle_sysrq_char(&uap->port, ch & 255))
- goto ignore_char;
-
- uart_insert_char(&uap->port, ch, UART011_DR_OE, ch, flag);
+ pl011_fifo_to_tty(uap);
- ignore_char:
- status = readw(uap->port.membase + UART01x_FR);
- }
spin_unlock(&uap->port.lock);
tty_flip_buffer_push(tty);
+ /*
+ * If we were temporarily out of DMA mode for a while,
+ * attempt to switch back to DMA mode again.
+ */
+ if (pl011_dma_rx_available(uap)) {
+ if (pl011_dma_rx_trigger_dma(uap)) {
+ dev_dbg(uap->port.dev, "could not trigger RX DMA job "
+ "fall back to interrupt mode again\n");
+ uap->im |= UART011_RXIM;
+ } else
+ uap->im &= ~UART011_RXIM;
+ writew(uap->im, uap->port.membase + UART011_IMSC);
+ }
spin_lock(&uap->port.lock);
}
UART011_RXIS),
uap->port.membase + UART011_ICR);
- if (status & (UART011_RTIS|UART011_RXIS))
- pl011_rx_chars(uap);
+ if (status & (UART011_RTIS|UART011_RXIS)) {
+ if (pl011_dma_rx_running(uap))
+ pl011_dma_rx_irq(uap);
+ else
+ pl011_rx_chars(uap);
+ }
if (status & (UART011_DSRMIS|UART011_DCDMIS|
UART011_CTSMIS|UART011_RIMIS))
pl011_modem_status(uap);
pl011_dma_startup(uap);
/*
- * Finally, enable interrupts
+ * Finally, enable interrupts, only timeouts when using DMA
+ * if initial RX DMA job failed, start in interrupt mode
+ * as well.
*/
spin_lock_irq(&uap->port.lock);
- uap->im = UART011_RXIM | UART011_RTIM;
+ uap->im = UART011_RTIM;
+ if (!pl011_dma_rx_running(uap))
+ uap->im |= UART011_RXIM;
writew(uap->im, uap->port.membase + UART011_IMSC);
spin_unlock_irq(&uap->port.lock);
.cons = AMBA_CONSOLE,
};
-static int pl011_probe(struct amba_device *dev, struct amba_id *id)
+static int pl011_probe(struct amba_device *dev, const struct amba_id *id)
{
struct uart_amba_port *uap;
struct vendor_data *vendor = id->data;
projects / ~andy / linux / blobdiff