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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>
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Heikki Krogerus
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Greg Kroah-Hartman
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Jan 16, 2013
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -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" | ||
|
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| 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; | ||
|
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| dma->tx_running = 0; | ||
|
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| dma_sync_single_for_cpu(dma->txchan->device->dev, dma->tx_addr, | ||
| UART_XMIT_SIZE, DMA_TO_DEVICE); | ||
|
|
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| 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; | ||
|
|
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| dma_sync_single_for_cpu(dma->rxchan->device->dev, dma->rx_addr, | ||
| dma->rx_size, DMA_FROM_DEVICE); | ||
|
|
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| 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); | ||
| } | ||
|
|
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| 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; | ||
| } | ||
|
|
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| dma->tx_size = CIRC_CNT_TO_END(xmit->head, xmit->tail, UART_XMIT_SIZE); | ||
|
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| 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; | ||
|
|
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| dma->tx_running = 1; | ||
|
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| desc->callback = __dma_tx_complete; | ||
| desc->callback_param = p; | ||
|
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| dma->tx_cookie = dmaengine_submit(desc); | ||
|
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| dma_sync_single_for_device(dma->txchan->device->dev, dma->tx_addr, | ||
| UART_XMIT_SIZE, DMA_TO_DEVICE); | ||
|
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| dma_async_issue_pending(dma->txchan); | ||
|
|
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| 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; | ||
|
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||
| /* | ||
| * 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; | ||
| } | ||
|
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||
| 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; | ||
|
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| desc->callback = __dma_rx_complete; | ||
| desc->callback_param = p; | ||
|
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| dma->rx_cookie = dmaengine_submit(desc); | ||
|
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| dma_sync_single_for_device(dma->rxchan->device->dev, dma->rx_addr, | ||
| dma->rx_size, DMA_FROM_DEVICE); | ||
|
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| dma_async_issue_pending(dma->rxchan); | ||
|
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| 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; | ||
|
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| dma->rxconf.src_addr = p->port.mapbase + UART_RX; | ||
| dma->txconf.dst_addr = p->port.mapbase + UART_TX; | ||
|
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| dma_cap_zero(mask); | ||
| dma_cap_set(DMA_SLAVE, mask); | ||
|
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| /* Get a channel for RX */ | ||
| dma->rxchan = dma_request_channel(mask, dma->fn, dma->rx_param); | ||
| if (!dma->rxchan) | ||
| return -ENODEV; | ||
|
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| dmaengine_slave_config(dma->rxchan, &dma->rxconf); | ||
|
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| /* 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; | ||
| } | ||
|
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| dmaengine_slave_config(dma->txchan, &dma->txconf); | ||
|
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| /* RX buffer */ | ||
| if (!dma->rx_size) | ||
| dma->rx_size = PAGE_SIZE; | ||
|
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| 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); | ||
|
|
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| dev_dbg_ratelimited(p->port.dev, "got both dma channels\n"); | ||
|
|
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| return 0; | ||
| } | ||
| EXPORT_SYMBOL_GPL(serial8250_request_dma); | ||
|
|
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| void serial8250_release_dma(struct uart_8250_port *p) | ||
| { | ||
| struct uart_8250_dma *dma = p->dma; | ||
|
|
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| 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; | ||
|
|
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| /* 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; | ||
|
|
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| dev_dbg_ratelimited(p->port.dev, "dma channels released\n"); | ||
| } | ||
| EXPORT_SYMBOL_GPL(serial8250_release_dma); |
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