2 * 8250_dma.c - DMA Engine API support for 8250.c
4 * Copyright (C) 2013 Intel Corporation
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License as published by
8 * the Free Software Foundation; either version 2 of the License, or
9 * (at your option) any later version.
11 #include <linux/tty.h>
12 #include <linux/tty_flip.h>
13 #include <linux/serial_reg.h>
14 #include <linux/dma-mapping.h>
18 static void __dma_tx_complete(void *param
)
20 struct uart_8250_port
*p
= param
;
21 struct uart_8250_dma
*dma
= p
->dma
;
22 struct circ_buf
*xmit
= &p
->port
.state
->xmit
;
26 dma_sync_single_for_cpu(dma
->txchan
->device
->dev
, dma
->tx_addr
,
27 UART_XMIT_SIZE
, DMA_TO_DEVICE
);
29 spin_lock_irqsave(&p
->port
.lock
, flags
);
33 xmit
->tail
+= dma
->tx_size
;
34 xmit
->tail
&= UART_XMIT_SIZE
- 1;
35 p
->port
.icount
.tx
+= dma
->tx_size
;
37 if (uart_circ_chars_pending(xmit
) < WAKEUP_CHARS
)
38 uart_write_wakeup(&p
->port
);
40 ret
= serial8250_tx_dma(p
);
42 p
->ier
|= UART_IER_THRI
;
43 serial_port_out(&p
->port
, UART_IER
, p
->ier
);
46 spin_unlock_irqrestore(&p
->port
.lock
, flags
);
49 static void __dma_rx_complete(void *param
)
51 struct uart_8250_port
*p
= param
;
52 struct uart_8250_dma
*dma
= p
->dma
;
53 struct tty_port
*tty_port
= &p
->port
.state
->port
;
54 struct dma_tx_state state
;
58 dmaengine_tx_status(dma
->rxchan
, dma
->rx_cookie
, &state
);
60 count
= dma
->rx_size
- state
.residue
;
62 tty_insert_flip_string(tty_port
, dma
->rx_buf
, count
);
63 p
->port
.icount
.rx
+= count
;
65 tty_flip_buffer_push(tty_port
);
68 int serial8250_tx_dma(struct uart_8250_port
*p
)
70 struct uart_8250_dma
*dma
= p
->dma
;
71 struct circ_buf
*xmit
= &p
->port
.state
->xmit
;
72 struct dma_async_tx_descriptor
*desc
;
75 if (uart_tx_stopped(&p
->port
) || dma
->tx_running
||
76 uart_circ_empty(xmit
))
79 dma
->tx_size
= CIRC_CNT_TO_END(xmit
->head
, xmit
->tail
, UART_XMIT_SIZE
);
81 desc
= dmaengine_prep_slave_single(dma
->txchan
,
82 dma
->tx_addr
+ xmit
->tail
,
83 dma
->tx_size
, DMA_MEM_TO_DEV
,
84 DMA_PREP_INTERRUPT
| DMA_CTRL_ACK
);
91 desc
->callback
= __dma_tx_complete
;
92 desc
->callback_param
= p
;
94 dma
->tx_cookie
= dmaengine_submit(desc
);
96 dma_sync_single_for_device(dma
->txchan
->device
->dev
, dma
->tx_addr
,
97 UART_XMIT_SIZE
, DMA_TO_DEVICE
);
99 dma_async_issue_pending(dma
->txchan
);
102 if (p
->ier
& UART_IER_THRI
) {
103 p
->ier
&= ~UART_IER_THRI
;
104 serial_out(p
, UART_IER
, p
->ier
);
113 int serial8250_rx_dma(struct uart_8250_port
*p
)
115 struct uart_8250_dma
*dma
= p
->dma
;
116 struct dma_async_tx_descriptor
*desc
;
121 desc
= dmaengine_prep_slave_single(dma
->rxchan
, dma
->rx_addr
,
122 dma
->rx_size
, DMA_DEV_TO_MEM
,
123 DMA_PREP_INTERRUPT
| DMA_CTRL_ACK
);
128 desc
->callback
= __dma_rx_complete
;
129 desc
->callback_param
= p
;
131 dma
->rx_cookie
= dmaengine_submit(desc
);
133 dma_async_issue_pending(dma
->rxchan
);
138 void serial8250_rx_dma_flush(struct uart_8250_port
*p
)
140 struct uart_8250_dma
*dma
= p
->dma
;
142 if (dma
->rx_running
) {
143 dmaengine_pause(dma
->rxchan
);
144 __dma_rx_complete(p
);
145 dmaengine_terminate_all(dma
->rxchan
);
149 int serial8250_request_dma(struct uart_8250_port
*p
)
151 struct uart_8250_dma
*dma
= p
->dma
;
153 struct dma_slave_caps caps
;
156 /* Default slave configuration parameters */
157 dma
->rxconf
.direction
= DMA_DEV_TO_MEM
;
158 dma
->rxconf
.src_addr_width
= DMA_SLAVE_BUSWIDTH_1_BYTE
;
159 dma
->rxconf
.src_addr
= p
->port
.mapbase
+ UART_RX
;
161 dma
->txconf
.direction
= DMA_MEM_TO_DEV
;
162 dma
->txconf
.dst_addr_width
= DMA_SLAVE_BUSWIDTH_1_BYTE
;
163 dma
->txconf
.dst_addr
= p
->port
.mapbase
+ UART_TX
;
166 dma_cap_set(DMA_SLAVE
, mask
);
168 /* Get a channel for RX */
169 dma
->rxchan
= dma_request_slave_channel_compat(mask
,
170 dma
->fn
, dma
->rx_param
,
175 /* 8250 rx dma requires dmaengine driver to support pause/terminate */
176 ret
= dma_get_slave_caps(dma
->rxchan
, &caps
);
179 if (!caps
.cmd_pause
|| !caps
.cmd_terminate
||
180 caps
.residue_granularity
== DMA_RESIDUE_GRANULARITY_DESCRIPTOR
) {
185 dmaengine_slave_config(dma
->rxchan
, &dma
->rxconf
);
187 /* Get a channel for TX */
188 dma
->txchan
= dma_request_slave_channel_compat(mask
,
189 dma
->fn
, dma
->tx_param
,
196 /* 8250 tx dma requires dmaengine driver to support terminate */
197 ret
= dma_get_slave_caps(dma
->txchan
, &caps
);
200 if (!caps
.cmd_terminate
) {
205 dmaengine_slave_config(dma
->txchan
, &dma
->txconf
);
209 dma
->rx_size
= PAGE_SIZE
;
211 dma
->rx_buf
= dma_alloc_coherent(dma
->rxchan
->device
->dev
, dma
->rx_size
,
212 &dma
->rx_addr
, GFP_KERNEL
);
219 dma
->tx_addr
= dma_map_single(dma
->txchan
->device
->dev
,
220 p
->port
.state
->xmit
.buf
,
223 if (dma_mapping_error(dma
->txchan
->device
->dev
, dma
->tx_addr
)) {
224 dma_free_coherent(dma
->rxchan
->device
->dev
, dma
->rx_size
,
225 dma
->rx_buf
, dma
->rx_addr
);
230 dev_dbg_ratelimited(p
->port
.dev
, "got both dma channels\n");
234 dma_release_channel(dma
->txchan
);
236 dma_release_channel(dma
->rxchan
);
239 EXPORT_SYMBOL_GPL(serial8250_request_dma
);
241 void serial8250_release_dma(struct uart_8250_port
*p
)
243 struct uart_8250_dma
*dma
= p
->dma
;
248 /* Release RX resources */
249 dmaengine_terminate_all(dma
->rxchan
);
250 dma_free_coherent(dma
->rxchan
->device
->dev
, dma
->rx_size
, dma
->rx_buf
,
252 dma_release_channel(dma
->rxchan
);
255 /* Release TX resources */
256 dmaengine_terminate_all(dma
->txchan
);
257 dma_unmap_single(dma
->txchan
->device
->dev
, dma
->tx_addr
,
258 UART_XMIT_SIZE
, DMA_TO_DEVICE
);
259 dma_release_channel(dma
->txchan
);
263 dev_dbg_ratelimited(p
->port
.dev
, "dma channels released\n");
265 EXPORT_SYMBOL_GPL(serial8250_release_dma
);