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@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/drivers/tty/serial/8250/8250.c b/drivers/tty/serial/8250/8250.c
index e2ac25a..cb7db5a 100644
--- a/drivers/tty/serial/8250/8250.c
+++ b/drivers/tty/serial/8250/8250.c
@@ -1269,7 +1269,9 @@
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);
@@ -1467,6 +1469,7 @@
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;
@@ -1477,8 +1480,13 @@
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);
@@ -2121,6 +2129,18 @@
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.
@@ -2153,6 +2173,9 @@
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 */
@@ -3217,6 +3240,8 @@
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,