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>hifive-unleashed-5.1
Heikki Krogerus
Greg Kroah-Hartman
parent
6a7320c466
commit
9ee4b83e51
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@ -1269,7 +1269,9 @@ static void serial8250_start_tx(struct uart_port *port)
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struct uart_8250_port *up =
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container_of(port, struct uart_8250_port, port);
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if (!(up->ier & UART_IER_THRI)) {
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if (up->dma && !serial8250_tx_dma(up)) {
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return;
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} else if (!(up->ier & UART_IER_THRI)) {
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up->ier |= UART_IER_THRI;
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serial_port_out(port, UART_IER, up->ier);
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@ -1467,6 +1469,7 @@ int serial8250_handle_irq(struct uart_port *port, unsigned int iir)
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unsigned long flags;
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struct uart_8250_port *up =
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container_of(port, struct uart_8250_port, port);
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int dma_err = 0;
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if (iir & UART_IIR_NO_INT)
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return 0;
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@ -1477,8 +1480,13 @@ int serial8250_handle_irq(struct uart_port *port, unsigned int iir)
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DEBUG_INTR("status = %x...", status);
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if (status & (UART_LSR_DR | UART_LSR_BI))
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status = serial8250_rx_chars(up, status);
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if (status & (UART_LSR_DR | UART_LSR_BI)) {
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if (up->dma)
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dma_err = serial8250_rx_dma(up, iir);
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if (!up->dma || dma_err)
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status = serial8250_rx_chars(up, status);
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}
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serial8250_modem_status(up);
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if (status & UART_LSR_THRE)
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serial8250_tx_chars(up);
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@ -2120,6 +2128,18 @@ dont_test_tx_en:
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up->lsr_saved_flags = 0;
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up->msr_saved_flags = 0;
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/*
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* Request DMA channels for both RX and TX.
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*/
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if (up->dma) {
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retval = serial8250_request_dma(up);
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if (retval) {
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pr_warn_ratelimited("ttyS%d - failed to request DMA\n",
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serial_index(port));
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up->dma = NULL;
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}
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}
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/*
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* Finally, enable interrupts. Note: Modem status interrupts
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* are set via set_termios(), which will be occurring imminently
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@ -2153,6 +2173,9 @@ static void serial8250_shutdown(struct uart_port *port)
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up->ier = 0;
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serial_port_out(port, UART_IER, 0);
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if (up->dma)
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serial8250_release_dma(up);
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spin_lock_irqsave(&port->lock, flags);
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if (port->flags & UPF_FOURPORT) {
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/* reset interrupts on the AST Fourport board */
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@ -3217,6 +3240,8 @@ int serial8250_register_8250_port(struct uart_8250_port *up)
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uart->dl_read = up->dl_read;
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if (up->dl_write)
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uart->dl_write = up->dl_write;
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if (up->dma)
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uart->dma = up->dma;
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if (serial8250_isa_config != NULL)
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serial8250_isa_config(0, &uart->port,
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@ -12,6 +12,35 @@
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*/
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#include <linux/serial_8250.h>
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#include <linux/dmaengine.h>
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struct uart_8250_dma {
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dma_filter_fn fn;
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void *rx_param;
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void *tx_param;
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int rx_chan_id;
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int tx_chan_id;
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struct dma_slave_config rxconf;
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struct dma_slave_config txconf;
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struct dma_chan *rxchan;
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struct dma_chan *txchan;
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dma_addr_t rx_addr;
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dma_addr_t tx_addr;
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dma_cookie_t rx_cookie;
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dma_cookie_t tx_cookie;
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void *rx_buf;
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size_t rx_size;
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size_t tx_size;
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unsigned char tx_running:1;
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};
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struct old_serial_port {
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unsigned int uart;
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@ -142,3 +171,24 @@ static inline int is_omap1510_8250(struct uart_8250_port *pt)
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return 0;
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}
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#endif
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#ifdef CONFIG_SERIAL_8250_DMA
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extern int serial8250_tx_dma(struct uart_8250_port *);
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extern int serial8250_rx_dma(struct uart_8250_port *, unsigned int iir);
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extern int serial8250_request_dma(struct uart_8250_port *);
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extern void serial8250_release_dma(struct uart_8250_port *);
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#else
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static inline int serial8250_tx_dma(struct uart_8250_port *p)
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{
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return -1;
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}
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static inline int serial8250_rx_dma(struct uart_8250_port *p, unsigned int iir)
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{
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return -1;
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}
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static inline int serial8250_request_dma(struct uart_8250_port *p)
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{
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return -1;
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}
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static inline void serial8250_release_dma(struct uart_8250_port *p) { }
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#endif
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@ -0,0 +1,213 @@
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/*
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* 8250_dma.c - DMA Engine API support for 8250.c
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*
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* Copyright (C) 2013 Intel Corporation
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*/
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#include <linux/tty.h>
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#include <linux/tty_flip.h>
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#include <linux/serial_reg.h>
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#include <linux/dma-mapping.h>
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#include "8250.h"
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static void __dma_tx_complete(void *param)
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{
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struct uart_8250_port *p = param;
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struct uart_8250_dma *dma = p->dma;
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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,
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UART_XMIT_SIZE, DMA_TO_DEVICE);
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xmit->tail += dma->tx_size;
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xmit->tail &= UART_XMIT_SIZE - 1;
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p->port.icount.tx += dma->tx_size;
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if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
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uart_write_wakeup(&p->port);
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if (!uart_circ_empty(xmit) && !uart_tx_stopped(&p->port)) {
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serial8250_tx_dma(p);
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uart_write_wakeup(&p->port);
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}
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}
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static void __dma_rx_complete(void *param)
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{
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struct uart_8250_port *p = param;
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struct uart_8250_dma *dma = p->dma;
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struct tty_struct *tty = p->port.state->port.tty;
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struct dma_tx_state state;
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dma_sync_single_for_cpu(dma->rxchan->device->dev, dma->rx_addr,
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dma->rx_size, DMA_FROM_DEVICE);
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dmaengine_tx_status(dma->rxchan, dma->rx_cookie, &state);
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dmaengine_terminate_all(dma->rxchan);
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tty_insert_flip_string(tty, dma->rx_buf, dma->rx_size - state.residue);
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p->port.icount.rx += dma->rx_size - state.residue;
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tty_flip_buffer_push(tty);
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}
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int serial8250_tx_dma(struct uart_8250_port *p)
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{
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struct uart_8250_dma *dma = p->dma;
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struct circ_buf *xmit = &p->port.state->xmit;
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struct dma_async_tx_descriptor *desc;
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if (dma->tx_running) {
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uart_write_wakeup(&p->port);
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return -EBUSY;
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}
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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,
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dma->tx_addr + xmit->tail,
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dma->tx_size, DMA_MEM_TO_DEV,
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DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
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if (!desc)
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return -EBUSY;
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dma->tx_running = 1;
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desc->callback = __dma_tx_complete;
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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,
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UART_XMIT_SIZE, DMA_TO_DEVICE);
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dma_async_issue_pending(dma->txchan);
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return 0;
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}
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EXPORT_SYMBOL_GPL(serial8250_tx_dma);
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int serial8250_rx_dma(struct uart_8250_port *p, unsigned int iir)
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{
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struct uart_8250_dma *dma = p->dma;
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struct dma_async_tx_descriptor *desc;
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struct dma_tx_state state;
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int dma_status;
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/*
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* If RCVR FIFO trigger level was not reached, complete the transfer and
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* let 8250.c copy the remaining data.
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*/
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if ((iir & 0x3f) == UART_IIR_RX_TIMEOUT) {
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dma_status = dmaengine_tx_status(dma->rxchan, dma->rx_cookie,
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&state);
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if (dma_status == DMA_IN_PROGRESS) {
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dmaengine_pause(dma->rxchan);
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__dma_rx_complete(p);
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}
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return -ETIMEDOUT;
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}
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desc = dmaengine_prep_slave_single(dma->rxchan, dma->rx_addr,
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dma->rx_size, DMA_DEV_TO_MEM,
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DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
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if (!desc)
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return -EBUSY;
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desc->callback = __dma_rx_complete;
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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,
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dma->rx_size, DMA_FROM_DEVICE);
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dma_async_issue_pending(dma->rxchan);
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return 0;
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}
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EXPORT_SYMBOL_GPL(serial8250_rx_dma);
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int serial8250_request_dma(struct uart_8250_port *p)
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{
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struct uart_8250_dma *dma = p->dma;
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dma_cap_mask_t mask;
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dma->rxconf.src_addr = p->port.mapbase + UART_RX;
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dma->txconf.dst_addr = p->port.mapbase + UART_TX;
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dma_cap_zero(mask);
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dma_cap_set(DMA_SLAVE, mask);
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/* Get a channel for RX */
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dma->rxchan = dma_request_channel(mask, dma->fn, dma->rx_param);
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if (!dma->rxchan)
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return -ENODEV;
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dmaengine_slave_config(dma->rxchan, &dma->rxconf);
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/* Get a channel for TX */
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dma->txchan = dma_request_channel(mask, dma->fn, dma->tx_param);
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if (!dma->txchan) {
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dma_release_channel(dma->rxchan);
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return -ENODEV;
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}
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dmaengine_slave_config(dma->txchan, &dma->txconf);
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/* RX buffer */
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if (!dma->rx_size)
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dma->rx_size = PAGE_SIZE;
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dma->rx_buf = dma_alloc_coherent(dma->rxchan->device->dev, dma->rx_size,
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&dma->rx_addr, GFP_KERNEL);
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if (!dma->rx_buf) {
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dma_release_channel(dma->rxchan);
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dma_release_channel(dma->txchan);
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return -ENOMEM;
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}
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/* TX buffer */
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dma->tx_addr = dma_map_single(dma->txchan->device->dev,
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p->port.state->xmit.buf,
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UART_XMIT_SIZE,
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DMA_TO_DEVICE);
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dev_dbg_ratelimited(p->port.dev, "got both dma channels\n");
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return 0;
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}
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EXPORT_SYMBOL_GPL(serial8250_request_dma);
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void serial8250_release_dma(struct uart_8250_port *p)
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{
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struct uart_8250_dma *dma = p->dma;
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if (!dma)
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return;
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/* Release RX resources */
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dmaengine_terminate_all(dma->rxchan);
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dma_free_coherent(dma->rxchan->device->dev, dma->rx_size, dma->rx_buf,
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dma->rx_addr);
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dma_release_channel(dma->rxchan);
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dma->rxchan = NULL;
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/* Release TX resources */
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dmaengine_terminate_all(dma->txchan);
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dma_unmap_single(dma->txchan->device->dev, dma->tx_addr,
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UART_XMIT_SIZE, DMA_TO_DEVICE);
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dma_release_channel(dma->txchan);
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dma->txchan = NULL;
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dma->tx_running = 0;
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dev_dbg_ratelimited(p->port.dev, "dma channels released\n");
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}
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EXPORT_SYMBOL_GPL(serial8250_release_dma);
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@ -84,6 +84,14 @@ config SERIAL_8250_GSC
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depends on SERIAL_8250 && GSC
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default SERIAL_8250
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config SERIAL_8250_DMA
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bool "DMA support for 16550 compatible UART controllers" if EXPERT
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depends on SERIAL_8250 && DMADEVICES=y
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default SERIAL_8250
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help
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This builds DMA support that can be used with 8250/16650
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compatible UART controllers that support DMA signaling.
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config SERIAL_8250_PCI
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tristate "8250/16550 PCI device support" if EXPERT
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depends on SERIAL_8250 && PCI
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@ -5,6 +5,7 @@
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obj-$(CONFIG_SERIAL_8250) += 8250_core.o
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8250_core-y := 8250.o
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8250_core-$(CONFIG_SERIAL_8250_PNP) += 8250_pnp.o
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8250_core-$(CONFIG_SERIAL_8250_DMA) += 8250_dma.o
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obj-$(CONFIG_SERIAL_8250_GSC) += 8250_gsc.o
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obj-$(CONFIG_SERIAL_8250_PCI) += 8250_pci.o
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obj-$(CONFIG_SERIAL_8250_HP300) += 8250_hp300.o
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@ -59,6 +59,8 @@ enum {
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PLAT8250_DEV_SM501,
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};
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struct uart_8250_dma;
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/*
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* This should be used by drivers which want to register
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* their own 8250 ports without registering their own
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@ -91,6 +93,8 @@ struct uart_8250_port {
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#define MSR_SAVE_FLAGS UART_MSR_ANY_DELTA
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unsigned char msr_saved_flags;
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struct uart_8250_dma *dma;
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/* 8250 specific callbacks */
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int (*dl_read)(struct uart_8250_port *);
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void (*dl_write)(struct uart_8250_port *, int);
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