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Date: Thu, 10 Jan 2013 11:25:11 +0200
From: Heikki Krogerus <heikki.krogerus@...ux.intel.com>
To: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc: Alan Cox <alan@...ux.intel.com>, Jamie Iles <jamie@...ieiles.com>,
linux-serial@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCHv3 7/8] serial: 8250: Add support for dmaengine
Add support for dmaengine API. The drivers can implement the
struct uart_8250_dma member in struct uart_8250_port and
8250.c can take care of the rest.
Signed-off-by: Heikki Krogerus <heikki.krogerus@...ux.intel.com>
---
drivers/tty/serial/8250/8250.c | 31 +++++-
drivers/tty/serial/8250/8250.h | 50 +++++++++
drivers/tty/serial/8250/8250_dma.c | 213 ++++++++++++++++++++++++++++++++++++
drivers/tty/serial/8250/Kconfig | 8 ++
drivers/tty/serial/8250/Makefile | 1 +
include/linux/serial_8250.h | 4 +
6 files changed, 304 insertions(+), 3 deletions(-)
create mode 100644 drivers/tty/serial/8250/8250_dma.c
diff --git a/drivers/tty/serial/8250/8250.c b/drivers/tty/serial/8250/8250.c
index da3f828..f952993 100644
--- a/drivers/tty/serial/8250/8250.c
+++ b/drivers/tty/serial/8250/8250.c
@@ -1335,7 +1335,9 @@ static void serial8250_start_tx(struct uart_port *port)
struct uart_8250_port *up =
container_of(port, struct uart_8250_port, port);
- if (!(up->ier & UART_IER_THRI)) {
+ if (up->dma && !serial8250_tx_dma(up)) {
+ return;
+ } else if (!(up->ier & UART_IER_THRI)) {
up->ier |= UART_IER_THRI;
serial_port_out(port, UART_IER, up->ier);
@@ -1536,6 +1538,7 @@ int serial8250_handle_irq(struct uart_port *port, unsigned int iir)
unsigned long flags;
struct uart_8250_port *up =
container_of(port, struct uart_8250_port, port);
+ int dma_err = 0;
if (iir & UART_IIR_NO_INT)
return 0;
@@ -1546,8 +1549,13 @@ int serial8250_handle_irq(struct uart_port *port, unsigned int iir)
DEBUG_INTR("status = %x...", status);
- if (status & (UART_LSR_DR | UART_LSR_BI))
- status = serial8250_rx_chars(up, status);
+ if (status & (UART_LSR_DR | UART_LSR_BI)) {
+ if (up->dma)
+ dma_err = serial8250_rx_dma(up, iir);
+
+ if (!up->dma || dma_err)
+ status = serial8250_rx_chars(up, status);
+ }
serial8250_modem_status(up);
if (status & UART_LSR_THRE)
serial8250_tx_chars(up);
@@ -2190,6 +2198,18 @@ dont_test_tx_en:
up->msr_saved_flags = 0;
/*
+ * Request DMA channels for both RX and TX.
+ */
+ if (up->dma) {
+ retval = serial8250_request_dma(up);
+ if (retval) {
+ pr_warn_ratelimited("ttyS%d - failed to request DMA\n",
+ serial_index(port));
+ up->dma = NULL;
+ }
+ }
+
+ /*
* Finally, enable interrupts. Note: Modem status interrupts
* are set via set_termios(), which will be occurring imminently
* anyway, so we don't enable them here.
@@ -2222,6 +2242,9 @@ static void serial8250_shutdown(struct uart_port *port)
up->ier = 0;
serial_port_out(port, UART_IER, 0);
+ if (up->dma)
+ serial8250_release_dma(up);
+
spin_lock_irqsave(&port->lock, flags);
if (port->flags & UPF_FOURPORT) {
/* reset interrupts on the AST Fourport board */
@@ -3286,6 +3309,8 @@ int serial8250_register_8250_port(struct uart_8250_port *up)
uart->dl_read = up->dl_read;
if (up->dl_write)
uart->dl_write = up->dl_write;
+ if (up->dma)
+ uart->dma = up->dma;
if (serial8250_isa_config != NULL)
serial8250_isa_config(0, &uart->port,
diff --git a/drivers/tty/serial/8250/8250.h b/drivers/tty/serial/8250/8250.h
index 3b4ea84..363d549 100644
--- a/drivers/tty/serial/8250/8250.h
+++ b/drivers/tty/serial/8250/8250.h
@@ -12,6 +12,35 @@
*/
#include <linux/serial_8250.h>
+#include <linux/dmaengine.h>
+
+struct uart_8250_dma {
+ dma_filter_fn fn;
+ void *rx_param;
+ void *tx_param;
+
+ int rx_chan_id;
+ int tx_chan_id;
+
+ struct dma_slave_config rxconf;
+ struct dma_slave_config txconf;
+
+ struct dma_chan *rxchan;
+ struct dma_chan *txchan;
+
+ dma_addr_t rx_addr;
+ dma_addr_t tx_addr;
+
+ dma_cookie_t rx_cookie;
+ dma_cookie_t tx_cookie;
+
+ void *rx_buf;
+
+ size_t rx_size;
+ size_t tx_size;
+
+ unsigned char tx_running:1;
+};
struct old_serial_port {
unsigned int uart;
@@ -142,3 +171,24 @@ static inline int is_omap1510_8250(struct uart_8250_port *pt)
return 0;
}
#endif
+
+#ifdef CONFIG_SERIAL_8250_DMA
+extern int serial8250_tx_dma(struct uart_8250_port *);
+extern int serial8250_rx_dma(struct uart_8250_port *, unsigned int iir);
+extern int serial8250_request_dma(struct uart_8250_port *);
+extern void serial8250_release_dma(struct uart_8250_port *);
+#else
+static inline int serial8250_tx_dma(struct uart_8250_port *p)
+{
+ return -1;
+}
+static inline int serial8250_rx_dma(struct uart_8250_port *p, unsigned int iir)
+{
+ return -1;
+}
+static inline int serial8250_request_dma(struct uart_8250_port *p)
+{
+ return -1;
+}
+static inline void serial8250_release_dma(struct uart_8250_port *p) { }
+#endif
diff --git a/drivers/tty/serial/8250/8250_dma.c b/drivers/tty/serial/8250/8250_dma.c
new file mode 100644
index 0000000..95516a1
--- /dev/null
+++ b/drivers/tty/serial/8250/8250_dma.c
@@ -0,0 +1,213 @@
+/*
+ * 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;
+
+ dma->tx_running = 0;
+
+ dma_sync_single_for_cpu(dma->txchan->device->dev, dma->tx_addr,
+ UART_XMIT_SIZE, DMA_TO_DEVICE);
+
+ 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);
+
+ if (!uart_circ_empty(xmit) && !uart_tx_stopped(&p->port)) {
+ serial8250_tx_dma(p);
+ uart_write_wakeup(&p->port);
+ }
+}
+
+static void __dma_rx_complete(void *param)
+{
+ struct uart_8250_port *p = param;
+ struct uart_8250_dma *dma = p->dma;
+ struct tty_struct *tty = p->port.state->port.tty;
+ struct dma_tx_state state;
+
+ dma_sync_single_for_cpu(dma->rxchan->device->dev, dma->rx_addr,
+ dma->rx_size, DMA_FROM_DEVICE);
+
+ dmaengine_tx_status(dma->rxchan, dma->rx_cookie, &state);
+ dmaengine_terminate_all(dma->rxchan);
+
+ tty_insert_flip_string(tty, dma->rx_buf, dma->rx_size - state.residue);
+ p->port.icount.rx += dma->rx_size - state.residue;
+
+ tty_flip_buffer_push(tty);
+}
+
+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;
+
+ if (dma->tx_running) {
+ uart_write_wakeup(&p->port);
+ return -EBUSY;
+ }
+
+ dma->tx_size = CIRC_CNT_TO_END(xmit->head, xmit->tail, UART_XMIT_SIZE);
+
+ 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)
+ return -EBUSY;
+
+ 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);
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(serial8250_tx_dma);
+
+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;
+ struct dma_tx_state state;
+ int dma_status;
+
+ /*
+ * If RCVR FIFO trigger level was not reached, complete the transfer and
+ * let 8250.c copy the remaining data.
+ */
+ if ((iir & 0x3f) == UART_IIR_RX_TIMEOUT) {
+ dma_status = dmaengine_tx_status(dma->rxchan, dma->rx_cookie,
+ &state);
+ if (dma_status == DMA_IN_PROGRESS) {
+ dmaengine_pause(dma->rxchan);
+ __dma_rx_complete(p);
+ }
+ return -ETIMEDOUT;
+ }
+
+ 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;
+
+ 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;
+}
+EXPORT_SYMBOL_GPL(serial8250_rx_dma);
+
+int serial8250_request_dma(struct uart_8250_port *p)
+{
+ struct uart_8250_dma *dma = p->dma;
+ dma_cap_mask_t mask;
+
+ dma->rxconf.src_addr = p->port.mapbase + UART_RX;
+ 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_channel(mask, dma->fn, dma->rx_param);
+ if (!dma->rxchan)
+ return -ENODEV;
+
+ dmaengine_slave_config(dma->rxchan, &dma->rxconf);
+
+ /* Get a channel for TX */
+ dma->txchan = dma_request_channel(mask, dma->fn, dma->tx_param);
+ 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) {
+ dma_release_channel(dma->rxchan);
+ dma_release_channel(dma->txchan);
+ return -ENOMEM;
+ }
+
+ /* TX buffer */
+ dma->tx_addr = dma_map_single(dma->txchan->device->dev,
+ p->port.state->xmit.buf,
+ UART_XMIT_SIZE,
+ DMA_TO_DEVICE);
+
+ dev_dbg_ratelimited(p->port.dev, "got both dma channels\n");
+
+ return 0;
+}
+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);
diff --git a/drivers/tty/serial/8250/Kconfig b/drivers/tty/serial/8250/Kconfig
index 11adff1..2748125 100644
--- a/drivers/tty/serial/8250/Kconfig
+++ b/drivers/tty/serial/8250/Kconfig
@@ -84,6 +84,14 @@ config SERIAL_8250_GSC
depends on SERIAL_8250 && GSC
default SERIAL_8250
+config SERIAL_8250_DMA
+ bool "DMA support for 16550 compatible UART controllers" if EXPERT
+ depends on SERIAL_8250 && DMADEVICES=y
+ default SERIAL_8250
+ help
+ This builds DMA support that can be used with 8250/16650
+ compatible UART controllers that support DMA signaling.
+
config SERIAL_8250_PCI
tristate "8250/16550 PCI device support" if EXPERT
depends on SERIAL_8250 && PCI
diff --git a/drivers/tty/serial/8250/Makefile b/drivers/tty/serial/8250/Makefile
index 108fe7f..a23838a 100644
--- a/drivers/tty/serial/8250/Makefile
+++ b/drivers/tty/serial/8250/Makefile
@@ -5,6 +5,7 @@
obj-$(CONFIG_SERIAL_8250) += 8250_core.o
8250_core-y := 8250.o
8250_core-$(CONFIG_SERIAL_8250_PNP) += 8250_pnp.o
+8250_core-$(CONFIG_SERIAL_8250_DMA) += 8250_dma.o
obj-$(CONFIG_SERIAL_8250_GSC) += 8250_gsc.o
obj-$(CONFIG_SERIAL_8250_PCI) += 8250_pci.o
obj-$(CONFIG_SERIAL_8250_HP300) += 8250_hp300.o
diff --git a/include/linux/serial_8250.h b/include/linux/serial_8250.h
index c490d20..af47a8a 100644
--- a/include/linux/serial_8250.h
+++ b/include/linux/serial_8250.h
@@ -59,6 +59,8 @@ enum {
PLAT8250_DEV_SM501,
};
+struct uart_8250_dma;
+
/*
* This should be used by drivers which want to register
* their own 8250 ports without registering their own
@@ -91,6 +93,8 @@ struct uart_8250_port {
#define MSR_SAVE_FLAGS UART_MSR_ANY_DELTA
unsigned char msr_saved_flags;
+ struct uart_8250_dma *dma;
+
/* 8250 specific callbacks */
int (*dl_read)(struct uart_8250_port *);
void (*dl_write)(struct uart_8250_port *, int);
--
1.7.10.4
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