Initial import

1 files changed, 259 insertions, 0 deletions

diff --git a/drivers/tty/serial/8250/8250_dma.c b/drivers/tty/serial/8250/8250_dma.c
new file mode 100644
index 000000000..21d01a491
--- /dev/null
+++ b/drivers/tty/serial/8250/8250_dma.c
@@ -0,0 +1,259 @@
+/*
+ * 8250_dma.c - DMA Engine API support for 8250.c
+ *
+ * Copyright (C) 2013 Intel Corporation
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+#include <linux/tty.h>
+#include <linux/tty_flip.h>
+#include <linux/serial_reg.h>
+#include <linux/dma-mapping.h>
+
+#include "8250.h"
+
+static void __dma_tx_complete(void *param)
+{
+	struct uart_8250_port	*p = param;
+	struct uart_8250_dma	*dma = p->dma;
+	struct circ_buf		*xmit = &p->port.state->xmit;
+	unsigned long	flags;
+	int		ret;
+
+	dma_sync_single_for_cpu(dma->txchan->device->dev, dma->tx_addr,
+				UART_XMIT_SIZE, DMA_TO_DEVICE);
+
+	spin_lock_irqsave(&p->port.lock, flags);
+
+	dma->tx_running = 0;
+
+	xmit->tail += dma->tx_size;
+	xmit->tail &= UART_XMIT_SIZE - 1;
+	p->port.icount.tx += dma->tx_size;
+
+	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
+		uart_write_wakeup(&p->port);
+
+	ret = serial8250_tx_dma(p);
+	if (ret) {
+		p->ier |= UART_IER_THRI;
+		serial_port_out(&p->port, UART_IER, p->ier);
+	}
+
+	spin_unlock_irqrestore(&p->port.lock, flags);
+}
+
+static void __dma_rx_complete(void *param)
+{
+	struct uart_8250_port	*p = param;
+	struct uart_8250_dma	*dma = p->dma;
+	struct tty_port		*tty_port = &p->port.state->port;
+	struct dma_tx_state	state;
+	int			count;
+
+	dma_sync_single_for_cpu(dma->rxchan->device->dev, dma->rx_addr,
+				dma->rx_size, DMA_FROM_DEVICE);
+
+	dma->rx_running = 0;
+	dmaengine_tx_status(dma->rxchan, dma->rx_cookie, &state);
+
+	count = dma->rx_size - state.residue;
+
+	tty_insert_flip_string(tty_port, dma->rx_buf, count);
+	p->port.icount.rx += count;
+
+	tty_flip_buffer_push(tty_port);
+}
+
+int serial8250_tx_dma(struct uart_8250_port *p)
+{
+	struct uart_8250_dma		*dma = p->dma;
+	struct circ_buf			*xmit = &p->port.state->xmit;
+	struct dma_async_tx_descriptor	*desc;
+	int ret;
+
+	if (uart_tx_stopped(&p->port) || dma->tx_running ||
+	    uart_circ_empty(xmit))
+		return 0;
+
+	dma->tx_size = CIRC_CNT_TO_END(xmit->head, xmit->tail, UART_XMIT_SIZE);
+	if (dma->tx_size < p->port.fifosize) {
+		ret = -EINVAL;
+		goto err;
+	}
+
+	desc = dmaengine_prep_slave_single(dma->txchan,
+					   dma->tx_addr + xmit->tail,
+					   dma->tx_size, DMA_MEM_TO_DEV,
+					   DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
+	if (!desc) {
+		ret = -EBUSY;
+		goto err;
+	}
+
+	dma->tx_running = 1;
+	desc->callback = __dma_tx_complete;
+	desc->callback_param = p;
+
+	dma->tx_cookie = dmaengine_submit(desc);
+
+	dma_sync_single_for_device(dma->txchan->device->dev, dma->tx_addr,
+				   UART_XMIT_SIZE, DMA_TO_DEVICE);
+
+	dma_async_issue_pending(dma->txchan);
+	if (dma->tx_err) {
+		dma->tx_err = 0;
+		if (p->ier & UART_IER_THRI) {
+			p->ier &= ~UART_IER_THRI;
+			serial_out(p, UART_IER, p->ier);
+		}
+	}
+	return 0;
+err:
+	dma->tx_err = 1;
+	return ret;
+}
+
+int serial8250_rx_dma(struct uart_8250_port *p, unsigned int iir)
+{
+	struct uart_8250_dma		*dma = p->dma;
+	struct dma_async_tx_descriptor	*desc;
+
+	switch (iir & 0x3f) {
+	case UART_IIR_RLSI:
+		/* 8250_core handles errors and break interrupts */
+		return -EIO;
+	case UART_IIR_RX_TIMEOUT:
+		/*
+		 * If RCVR FIFO trigger level was not reached, complete the
+		 * transfer and let 8250_core copy the remaining data.
+		 */
+		if (dma->rx_running) {
+			dmaengine_pause(dma->rxchan);
+			__dma_rx_complete(p);
+			dmaengine_terminate_all(dma->rxchan);
+		}
+		return -ETIMEDOUT;
+	default:
+		break;
+	}
+
+	if (dma->rx_running)
+		return 0;
+
+	desc = dmaengine_prep_slave_single(dma->rxchan, dma->rx_addr,
+					   dma->rx_size, DMA_DEV_TO_MEM,
+					   DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
+	if (!desc)
+		return -EBUSY;
+
+	dma->rx_running = 1;
+	desc->callback = __dma_rx_complete;
+	desc->callback_param = p;
+
+	dma->rx_cookie = dmaengine_submit(desc);
+
+	dma_sync_single_for_device(dma->rxchan->device->dev, dma->rx_addr,
+				   dma->rx_size, DMA_FROM_DEVICE);
+
+	dma_async_issue_pending(dma->rxchan);
+
+	return 0;
+}
+
+int serial8250_request_dma(struct uart_8250_port *p)
+{
+	struct uart_8250_dma	*dma = p->dma;
+	dma_cap_mask_t		mask;
+
+	/* Default slave configuration parameters */
+	dma->rxconf.direction		= DMA_DEV_TO_MEM;
+	dma->rxconf.src_addr_width	= DMA_SLAVE_BUSWIDTH_1_BYTE;
+	dma->rxconf.src_addr		= p->port.mapbase + UART_RX;
+
+	dma->txconf.direction		= DMA_MEM_TO_DEV;
+	dma->txconf.dst_addr_width	= DMA_SLAVE_BUSWIDTH_1_BYTE;
+	dma->txconf.dst_addr		= p->port.mapbase + UART_TX;
+
+	dma_cap_zero(mask);
+	dma_cap_set(DMA_SLAVE, mask);
+
+	/* Get a channel for RX */
+	dma->rxchan = dma_request_slave_channel_compat(mask,
+						       dma->fn, dma->rx_param,
+						       p->port.dev, "rx");
+	if (!dma->rxchan)
+		return -ENODEV;
+
+	dmaengine_slave_config(dma->rxchan, &dma->rxconf);
+
+	/* Get a channel for TX */
+	dma->txchan = dma_request_slave_channel_compat(mask,
+						       dma->fn, dma->tx_param,
+						       p->port.dev, "tx");
+	if (!dma->txchan) {
+		dma_release_channel(dma->rxchan);
+		return -ENODEV;
+	}
+
+	dmaengine_slave_config(dma->txchan, &dma->txconf);
+
+	/* RX buffer */
+	if (!dma->rx_size)
+		dma->rx_size = PAGE_SIZE;
+
+	dma->rx_buf = dma_alloc_coherent(dma->rxchan->device->dev, dma->rx_size,
+					&dma->rx_addr, GFP_KERNEL);
+	if (!dma->rx_buf)
+		goto err;
+
+	/* TX buffer */
+	dma->tx_addr = dma_map_single(dma->txchan->device->dev,
+					p->port.state->xmit.buf,
+					UART_XMIT_SIZE,
+					DMA_TO_DEVICE);
+	if (dma_mapping_error(dma->txchan->device->dev, dma->tx_addr)) {
+		dma_free_coherent(dma->rxchan->device->dev, dma->rx_size,
+				  dma->rx_buf, dma->rx_addr);
+		goto err;
+	}
+
+	dev_dbg_ratelimited(p->port.dev, "got both dma channels\n");
+
+	return 0;
+err:
+	dma_release_channel(dma->rxchan);
+	dma_release_channel(dma->txchan);
+
+	return -ENOMEM;
+}
+EXPORT_SYMBOL_GPL(serial8250_request_dma);
+
+void serial8250_release_dma(struct uart_8250_port *p)
+{
+	struct uart_8250_dma *dma = p->dma;
+
+	if (!dma)
+		return;
+
+	/* Release RX resources */
+	dmaengine_terminate_all(dma->rxchan);
+	dma_free_coherent(dma->rxchan->device->dev, dma->rx_size, dma->rx_buf,
+			  dma->rx_addr);
+	dma_release_channel(dma->rxchan);
+	dma->rxchan = NULL;
+
+	/* Release TX resources */
+	dmaengine_terminate_all(dma->txchan);
+	dma_unmap_single(dma->txchan->device->dev, dma->tx_addr,
+			 UART_XMIT_SIZE, DMA_TO_DEVICE);
+	dma_release_channel(dma->txchan);
+	dma->txchan = NULL;
+	dma->tx_running = 0;
+
+	dev_dbg_ratelimited(p->port.dev, "dma channels released\n");
+}
+EXPORT_SYMBOL_GPL(serial8250_release_dma);