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7#include <linux/tty.h>
8#include <linux/tty_flip.h>
9#include <linux/serial_reg.h>
10#include <linux/dma-mapping.h>
11
12#include "8250.h"
13
14static void __dma_tx_complete(void *param)
15{
16 struct uart_8250_port *p = param;
17 struct uart_8250_dma *dma = p->dma;
18 struct circ_buf *xmit = &p->port.state->xmit;
19 unsigned long flags;
20 int ret;
21
22 dma_sync_single_for_cpu(dma->txchan->device->dev, dma->tx_addr,
23 UART_XMIT_SIZE, DMA_TO_DEVICE);
24
25 spin_lock_irqsave(&p->port.lock, flags);
26
27 dma->tx_running = 0;
28
29 xmit->tail += dma->tx_size;
30 xmit->tail &= UART_XMIT_SIZE - 1;
31 p->port.icount.tx += dma->tx_size;
32
33 if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
34 uart_write_wakeup(&p->port);
35
36 ret = serial8250_tx_dma(p);
37 if (ret)
38 serial8250_set_THRI(p);
39
40 spin_unlock_irqrestore(&p->port.lock, flags);
41}
42
43static void __dma_rx_complete(void *param)
44{
45 struct uart_8250_port *p = param;
46 struct uart_8250_dma *dma = p->dma;
47 struct tty_port *tty_port = &p->port.state->port;
48 struct dma_tx_state state;
49 int count;
50
51 dma->rx_running = 0;
52 dmaengine_tx_status(dma->rxchan, dma->rx_cookie, &state);
53
54 count = dma->rx_size - state.residue;
55
56 tty_insert_flip_string(tty_port, dma->rx_buf, count);
57 p->port.icount.rx += count;
58
59 tty_flip_buffer_push(tty_port);
60}
61
62int serial8250_tx_dma(struct uart_8250_port *p)
63{
64 struct uart_8250_dma *dma = p->dma;
65 struct circ_buf *xmit = &p->port.state->xmit;
66 struct dma_async_tx_descriptor *desc;
67 int ret;
68
69 if (dma->tx_running)
70 return 0;
71
72 if (uart_tx_stopped(&p->port) || uart_circ_empty(xmit)) {
73
74 serial8250_rpm_put_tx(p);
75 return 0;
76 }
77
78 dma->tx_size = CIRC_CNT_TO_END(xmit->head, xmit->tail, UART_XMIT_SIZE);
79
80 desc = dmaengine_prep_slave_single(dma->txchan,
81 dma->tx_addr + xmit->tail,
82 dma->tx_size, DMA_MEM_TO_DEV,
83 DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
84 if (!desc) {
85 ret = -EBUSY;
86 goto err;
87 }
88
89 dma->tx_running = 1;
90 desc->callback = __dma_tx_complete;
91 desc->callback_param = p;
92
93 dma->tx_cookie = dmaengine_submit(desc);
94
95 dma_sync_single_for_device(dma->txchan->device->dev, dma->tx_addr,
96 UART_XMIT_SIZE, DMA_TO_DEVICE);
97
98 dma_async_issue_pending(dma->txchan);
99 if (dma->tx_err) {
100 dma->tx_err = 0;
101 serial8250_clear_THRI(p);
102 }
103 return 0;
104err:
105 dma->tx_err = 1;
106 return ret;
107}
108
109int serial8250_rx_dma(struct uart_8250_port *p)
110{
111 struct uart_8250_dma *dma = p->dma;
112 struct dma_async_tx_descriptor *desc;
113
114 if (dma->rx_running)
115 return 0;
116
117 desc = dmaengine_prep_slave_single(dma->rxchan, dma->rx_addr,
118 dma->rx_size, DMA_DEV_TO_MEM,
119 DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
120 if (!desc)
121 return -EBUSY;
122
123 dma->rx_running = 1;
124 desc->callback = __dma_rx_complete;
125 desc->callback_param = p;
126
127 dma->rx_cookie = dmaengine_submit(desc);
128
129 dma_async_issue_pending(dma->rxchan);
130
131 return 0;
132}
133
134void serial8250_rx_dma_flush(struct uart_8250_port *p)
135{
136 struct uart_8250_dma *dma = p->dma;
137
138 if (dma->rx_running) {
139 dmaengine_pause(dma->rxchan);
140 __dma_rx_complete(p);
141 dmaengine_terminate_async(dma->rxchan);
142 }
143}
144EXPORT_SYMBOL_GPL(serial8250_rx_dma_flush);
145
146int serial8250_request_dma(struct uart_8250_port *p)
147{
148 struct uart_8250_dma *dma = p->dma;
149 phys_addr_t rx_dma_addr = dma->rx_dma_addr ?
150 dma->rx_dma_addr : p->port.mapbase;
151 phys_addr_t tx_dma_addr = dma->tx_dma_addr ?
152 dma->tx_dma_addr : p->port.mapbase;
153 dma_cap_mask_t mask;
154 struct dma_slave_caps caps;
155 int ret;
156
157
158 dma->rxconf.direction = DMA_DEV_TO_MEM;
159 dma->rxconf.src_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE;
160 dma->rxconf.src_addr = rx_dma_addr + UART_RX;
161
162 dma->txconf.direction = DMA_MEM_TO_DEV;
163 dma->txconf.dst_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE;
164 dma->txconf.dst_addr = tx_dma_addr + UART_TX;
165
166 dma_cap_zero(mask);
167 dma_cap_set(DMA_SLAVE, mask);
168
169
170 dma->rxchan = dma_request_slave_channel_compat(mask,
171 dma->fn, dma->rx_param,
172 p->port.dev, "rx");
173 if (!dma->rxchan)
174 return -ENODEV;
175
176
177 ret = dma_get_slave_caps(dma->rxchan, &caps);
178 if (ret)
179 goto release_rx;
180 if (!caps.cmd_pause || !caps.cmd_terminate ||
181 caps.residue_granularity == DMA_RESIDUE_GRANULARITY_DESCRIPTOR) {
182 ret = -EINVAL;
183 goto release_rx;
184 }
185
186 dmaengine_slave_config(dma->rxchan, &dma->rxconf);
187
188
189 dma->txchan = dma_request_slave_channel_compat(mask,
190 dma->fn, dma->tx_param,
191 p->port.dev, "tx");
192 if (!dma->txchan) {
193 ret = -ENODEV;
194 goto release_rx;
195 }
196
197
198 ret = dma_get_slave_caps(dma->txchan, &caps);
199 if (ret)
200 goto err;
201 if (!caps.cmd_terminate) {
202 ret = -EINVAL;
203 goto err;
204 }
205
206 dmaengine_slave_config(dma->txchan, &dma->txconf);
207
208
209 if (!dma->rx_size)
210 dma->rx_size = PAGE_SIZE;
211
212 dma->rx_buf = dma_alloc_coherent(dma->rxchan->device->dev, dma->rx_size,
213 &dma->rx_addr, GFP_KERNEL);
214 if (!dma->rx_buf) {
215 ret = -ENOMEM;
216 goto err;
217 }
218
219
220 dma->tx_addr = dma_map_single(dma->txchan->device->dev,
221 p->port.state->xmit.buf,
222 UART_XMIT_SIZE,
223 DMA_TO_DEVICE);
224 if (dma_mapping_error(dma->txchan->device->dev, dma->tx_addr)) {
225 dma_free_coherent(dma->rxchan->device->dev, dma->rx_size,
226 dma->rx_buf, dma->rx_addr);
227 ret = -ENOMEM;
228 goto err;
229 }
230
231 dev_dbg_ratelimited(p->port.dev, "got both dma channels\n");
232
233 return 0;
234err:
235 dma_release_channel(dma->txchan);
236release_rx:
237 dma_release_channel(dma->rxchan);
238 return ret;
239}
240EXPORT_SYMBOL_GPL(serial8250_request_dma);
241
242void serial8250_release_dma(struct uart_8250_port *p)
243{
244 struct uart_8250_dma *dma = p->dma;
245
246 if (!dma)
247 return;
248
249
250 dmaengine_terminate_sync(dma->rxchan);
251 dma_free_coherent(dma->rxchan->device->dev, dma->rx_size, dma->rx_buf,
252 dma->rx_addr);
253 dma_release_channel(dma->rxchan);
254 dma->rxchan = NULL;
255
256
257 dmaengine_terminate_sync(dma->txchan);
258 dma_unmap_single(dma->txchan->device->dev, dma->tx_addr,
259 UART_XMIT_SIZE, DMA_TO_DEVICE);
260 dma_release_channel(dma->txchan);
261 dma->txchan = NULL;
262 dma->tx_running = 0;
263
264 dev_dbg_ratelimited(p->port.dev, "dma channels released\n");
265}
266EXPORT_SYMBOL_GPL(serial8250_release_dma);
267
