1 /* 2 * 8250_dma.c - DMA Engine API support for 8250.c 3 * 4 * Copyright (C) 2013 Intel Corporation 5 * 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. 10 */ 11 #include <linux/tty.h> 12 #include <linux/tty_flip.h> 13 #include <linux/serial_reg.h> 14 #include <linux/dma-mapping.h> 15 16 #include "8250.h" 17 18 static void __dma_tx_complete(void *param) 19 { 20 struct uart_8250_port *p = param; 21 struct uart_8250_dma *dma = p->dma; 22 struct circ_buf *xmit = &p->port.state->xmit; 23 24 dma->tx_running = 0; 25 26 dma_sync_single_for_cpu(dma->txchan->device->dev, dma->tx_addr, 27 UART_XMIT_SIZE, DMA_TO_DEVICE); 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 if (!uart_circ_empty(xmit) && !uart_tx_stopped(&p->port)) 37 serial8250_tx_dma(p); 38 } 39 40 static void __dma_rx_complete(void *param) 41 { 42 struct uart_8250_port *p = param; 43 struct uart_8250_dma *dma = p->dma; 44 struct tty_port *tty_port = &p->port.state->port; 45 struct dma_tx_state state; 46 int count; 47 48 dma_sync_single_for_cpu(dma->rxchan->device->dev, dma->rx_addr, 49 dma->rx_size, DMA_FROM_DEVICE); 50 51 dmaengine_tx_status(dma->rxchan, dma->rx_cookie, &state); 52 dmaengine_terminate_all(dma->rxchan); 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 62 int 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 68 if (uart_tx_stopped(&p->port) || dma->tx_running || 69 uart_circ_empty(xmit)) 70 return 0; 71 72 dma->tx_size = CIRC_CNT_TO_END(xmit->head, xmit->tail, UART_XMIT_SIZE); 73 74 desc = dmaengine_prep_slave_single(dma->txchan, 75 dma->tx_addr + xmit->tail, 76 dma->tx_size, DMA_MEM_TO_DEV, 77 DMA_PREP_INTERRUPT | DMA_CTRL_ACK); 78 if (!desc) 79 return -EBUSY; 80 81 dma->tx_running = 1; 82 83 desc->callback = __dma_tx_complete; 84 desc->callback_param = p; 85 86 dma->tx_cookie = dmaengine_submit(desc); 87 88 dma_sync_single_for_device(dma->txchan->device->dev, dma->tx_addr, 89 UART_XMIT_SIZE, DMA_TO_DEVICE); 90 91 dma_async_issue_pending(dma->txchan); 92 93 return 0; 94 } 95 EXPORT_SYMBOL_GPL(serial8250_tx_dma); 96 97 int serial8250_rx_dma(struct uart_8250_port *p, unsigned int iir) 98 { 99 struct uart_8250_dma *dma = p->dma; 100 struct dma_async_tx_descriptor *desc; 101 struct dma_tx_state state; 102 int dma_status; 103 104 dma_status = dmaengine_tx_status(dma->rxchan, dma->rx_cookie, &state); 105 106 switch (iir & 0x3f) { 107 case UART_IIR_RLSI: 108 /* 8250_core handles errors and break interrupts */ 109 return -EIO; 110 case UART_IIR_RX_TIMEOUT: 111 /* 112 * If RCVR FIFO trigger level was not reached, complete the 113 * transfer and let 8250_core copy the remaining data. 114 */ 115 if (dma_status == DMA_IN_PROGRESS) { 116 dmaengine_pause(dma->rxchan); 117 __dma_rx_complete(p); 118 } 119 return -ETIMEDOUT; 120 default: 121 break; 122 } 123 124 if (dma_status) 125 return 0; 126 127 desc = dmaengine_prep_slave_single(dma->rxchan, dma->rx_addr, 128 dma->rx_size, DMA_DEV_TO_MEM, 129 DMA_PREP_INTERRUPT | DMA_CTRL_ACK); 130 if (!desc) 131 return -EBUSY; 132 133 desc->callback = __dma_rx_complete; 134 desc->callback_param = p; 135 136 dma->rx_cookie = dmaengine_submit(desc); 137 138 dma_sync_single_for_device(dma->rxchan->device->dev, dma->rx_addr, 139 dma->rx_size, DMA_FROM_DEVICE); 140 141 dma_async_issue_pending(dma->rxchan); 142 143 return 0; 144 } 145 EXPORT_SYMBOL_GPL(serial8250_rx_dma); 146 147 int serial8250_request_dma(struct uart_8250_port *p) 148 { 149 struct uart_8250_dma *dma = p->dma; 150 dma_cap_mask_t mask; 151 152 dma->rxconf.src_addr = p->port.mapbase + UART_RX; 153 dma->txconf.dst_addr = p->port.mapbase + UART_TX; 154 155 dma_cap_zero(mask); 156 dma_cap_set(DMA_SLAVE, mask); 157 158 /* Get a channel for RX */ 159 dma->rxchan = dma_request_slave_channel_compat(mask, 160 dma->fn, dma->rx_param, 161 p->port.dev, "rx"); 162 if (!dma->rxchan) 163 return -ENODEV; 164 165 dmaengine_slave_config(dma->rxchan, &dma->rxconf); 166 167 /* Get a channel for TX */ 168 dma->txchan = dma_request_slave_channel_compat(mask, 169 dma->fn, dma->tx_param, 170 p->port.dev, "tx"); 171 if (!dma->txchan) { 172 dma_release_channel(dma->rxchan); 173 return -ENODEV; 174 } 175 176 dmaengine_slave_config(dma->txchan, &dma->txconf); 177 178 /* RX buffer */ 179 if (!dma->rx_size) 180 dma->rx_size = PAGE_SIZE; 181 182 dma->rx_buf = dma_alloc_coherent(dma->rxchan->device->dev, dma->rx_size, 183 &dma->rx_addr, GFP_KERNEL); 184 if (!dma->rx_buf) { 185 dma_release_channel(dma->rxchan); 186 dma_release_channel(dma->txchan); 187 return -ENOMEM; 188 } 189 190 /* TX buffer */ 191 dma->tx_addr = dma_map_single(dma->txchan->device->dev, 192 p->port.state->xmit.buf, 193 UART_XMIT_SIZE, 194 DMA_TO_DEVICE); 195 196 dev_dbg_ratelimited(p->port.dev, "got both dma channels\n"); 197 198 return 0; 199 } 200 EXPORT_SYMBOL_GPL(serial8250_request_dma); 201 202 void serial8250_release_dma(struct uart_8250_port *p) 203 { 204 struct uart_8250_dma *dma = p->dma; 205 206 if (!dma) 207 return; 208 209 /* Release RX resources */ 210 dmaengine_terminate_all(dma->rxchan); 211 dma_free_coherent(dma->rxchan->device->dev, dma->rx_size, dma->rx_buf, 212 dma->rx_addr); 213 dma_release_channel(dma->rxchan); 214 dma->rxchan = NULL; 215 216 /* Release TX resources */ 217 dmaengine_terminate_all(dma->txchan); 218 dma_unmap_single(dma->txchan->device->dev, dma->tx_addr, 219 UART_XMIT_SIZE, DMA_TO_DEVICE); 220 dma_release_channel(dma->txchan); 221 dma->txchan = NULL; 222 dma->tx_running = 0; 223 224 dev_dbg_ratelimited(p->port.dev, "dma channels released\n"); 225 } 226 EXPORT_SYMBOL_GPL(serial8250_release_dma); 227