diff options
Diffstat (limited to 'drivers/serial')
| -rw-r--r-- | drivers/serial/Kconfig | 15 | ||||
| -rw-r--r-- | drivers/serial/atmel_serial.c | 392 |
2 files changed, 383 insertions, 24 deletions
diff --git a/drivers/serial/Kconfig b/drivers/serial/Kconfig index 84a054d7e98..b82595cf13e 100644 --- a/drivers/serial/Kconfig +++ b/drivers/serial/Kconfig @@ -380,6 +380,21 @@ config SERIAL_ATMEL_CONSOLE console is the device which receives all kernel messages and warnings and which allows logins in single user mode). +config SERIAL_ATMEL_PDC + bool "Support DMA transfers on AT91 / AT32 serial port" + depends on SERIAL_ATMEL + default y + help + Say Y here if you wish to use the PDC to do DMA transfers to + and from the Atmel AT91 / AT32 serial port. In order to + actually use DMA transfers, make sure that the use_dma_tx + and use_dma_rx members in the atmel_uart_data struct is set + appropriately for each port. + + Note that break and error handling currently doesn't work + properly when DMA is enabled. Make sure that ports where + this matters don't use DMA. + config SERIAL_ATMEL_TTYAT bool "Install as device ttyATn instead of ttySn" depends on SERIAL_ATMEL=y diff --git a/drivers/serial/atmel_serial.c b/drivers/serial/atmel_serial.c index f0f6ea3a9ee..d15ab224328 100644 --- a/drivers/serial/atmel_serial.c +++ b/drivers/serial/atmel_serial.c @@ -7,6 +7,8 @@ * Based on drivers/char/serial_sa1100.c, by Deep Blue Solutions Ltd. * Based on drivers/char/serial.c, by Linus Torvalds, Theodore Ts'o. * + * DMA support added by Chip Coldwell. + * * 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 @@ -33,6 +35,7 @@ #include <linux/sysrq.h> #include <linux/tty_flip.h> #include <linux/platform_device.h> +#include <linux/dma-mapping.h> #include <linux/atmel_pdc.h> #include <linux/atmel_serial.h> @@ -46,6 +49,10 @@ #include <asm/arch/gpio.h> #endif +#define PDC_BUFFER_SIZE 512 +/* Revisit: We should calculate this based on the actual port settings */ +#define PDC_RX_TIMEOUT (3 * 10) /* 3 bytes */ + #if defined(CONFIG_SERIAL_ATMEL_CONSOLE) && defined(CONFIG_MAGIC_SYSRQ) #define SUPPORT_SYSRQ #endif @@ -103,6 +110,13 @@ static int (*atmel_open_hook)(struct uart_port *); static void (*atmel_close_hook)(struct uart_port *); +struct atmel_dma_buffer { + unsigned char *buf; + dma_addr_t dma_addr; + unsigned int dma_size; + unsigned int ofs; +}; + struct atmel_uart_char { u16 status; u16 ch; @@ -119,6 +133,13 @@ struct atmel_uart_port { unsigned short suspended; /* is port suspended? */ int break_active; /* break being received */ + short use_dma_rx; /* enable PDC receiver */ + short pdc_rx_idx; /* current PDC RX buffer */ + struct atmel_dma_buffer pdc_rx[2]; /* PDC receier */ + + short use_dma_tx; /* enable PDC transmitter */ + struct atmel_dma_buffer pdc_tx; /* PDC transmitter */ + struct tasklet_struct tasklet; unsigned int irq_status; unsigned int irq_status_prev; @@ -132,6 +153,32 @@ static struct atmel_uart_port atmel_ports[ATMEL_MAX_UART]; static struct console atmel_console; #endif +#ifdef CONFIG_SERIAL_ATMEL_PDC +static bool atmel_use_dma_rx(struct uart_port *port) +{ + struct atmel_uart_port *atmel_port = (struct atmel_uart_port *)port; + + return atmel_port->use_dma_rx; +} + +static bool atmel_use_dma_tx(struct uart_port *port) +{ + struct atmel_uart_port *atmel_port = (struct atmel_uart_port *)port; + + return atmel_port->use_dma_tx; +} +#else +static bool atmel_use_dma_rx(struct uart_port *port) +{ + return false; +} + +static bool atmel_use_dma_tx(struct uart_port *port) +{ + return false; +} +#endif + /* * Return TIOCSER_TEMT when transmitter FIFO and Shift register is empty. */ @@ -213,7 +260,12 @@ static u_int atmel_get_mctrl(struct uart_port *port) */ static void atmel_stop_tx(struct uart_port *port) { - UART_PUT_IDR(port, ATMEL_US_TXRDY); + if (atmel_use_dma_tx(port)) { + /* disable PDC transmit */ + UART_PUT_PTCR(port, ATMEL_PDC_TXTDIS); + UART_PUT_IDR(port, ATMEL_US_ENDTX | ATMEL_US_TXBUFE); + } else + UART_PUT_IDR(port, ATMEL_US_TXRDY); } /* @@ -221,7 +273,17 @@ static void atmel_stop_tx(struct uart_port *port) */ static void atmel_start_tx(struct uart_port *port) { - UART_PUT_IER(port, ATMEL_US_TXRDY); + if (atmel_use_dma_tx(port)) { + if (UART_GET_PTSR(port) & ATMEL_PDC_TXTEN) + /* The transmitter is already running. Yes, we + really need this.*/ + return; + + UART_PUT_IER(port, ATMEL_US_ENDTX | ATMEL_US_TXBUFE); + /* re-enable PDC transmit */ + UART_PUT_PTCR(port, ATMEL_PDC_TXTEN); + } else + UART_PUT_IER(port, ATMEL_US_TXRDY); } /* @@ -229,7 +291,12 @@ static void atmel_start_tx(struct uart_port *port) */ static void atmel_stop_rx(struct uart_port *port) { - UART_PUT_IDR(port, ATMEL_US_RXRDY); + if (atmel_use_dma_rx(port)) { + /* disable PDC receive */ + UART_PUT_PTCR(port, ATMEL_PDC_RXTDIS); + UART_PUT_IDR(port, ATMEL_US_ENDRX | ATMEL_US_TIMEOUT); + } else + UART_PUT_IDR(port, ATMEL_US_RXRDY); } /* @@ -278,6 +345,27 @@ atmel_buffer_rx_char(struct uart_port *port, unsigned int status, } /* + * Deal with parity, framing and overrun errors. + */ +static void atmel_pdc_rxerr(struct uart_port *port, unsigned int status) +{ + /* clear error */ + UART_PUT_CR(port, ATMEL_US_RSTSTA); + + if (status & ATMEL_US_RXBRK) { + /* ignore side-effect */ + status &= ~(ATMEL_US_PARE | ATMEL_US_FRAME); + port->icount.brk++; + } + if (status & ATMEL_US_PARE) + port->icount.parity++; + if (status & ATMEL_US_FRAME) + port->icount.frame++; + if (status & ATMEL_US_OVRE) + port->icount.overrun++; +} + +/* * Characters received (called from interrupt handler) */ static void atmel_rx_chars(struct uart_port *port) @@ -364,6 +452,25 @@ atmel_handle_receive(struct uart_port *port, unsigned int pending) { struct atmel_uart_port *atmel_port = (struct atmel_uart_port *)port; + if (atmel_use_dma_rx(port)) { + /* + * PDC receive. Just schedule the tasklet and let it + * figure out the details. + * + * TODO: We're not handling error flags correctly at + * the moment. + */ + if (pending & (ATMEL_US_ENDRX | ATMEL_US_TIMEOUT)) { + UART_PUT_IDR(port, (ATMEL_US_ENDRX + | ATMEL_US_TIMEOUT)); + tasklet_schedule(&atmel_port->tasklet); + } + + if (pending & (ATMEL_US_RXBRK | ATMEL_US_OVRE | + ATMEL_US_FRAME | ATMEL_US_PARE)) + atmel_pdc_rxerr(port, pending); + } + /* Interrupt receive */ if (pending & ATMEL_US_RXRDY) atmel_rx_chars(port); @@ -386,10 +493,18 @@ atmel_handle_transmit(struct uart_port *port, unsigned int pending) { struct atmel_uart_port *atmel_port = (struct atmel_uart_port *)port; - /* Interrupt transmit */ - if (pending & ATMEL_US_TXRDY) { - UART_PUT_IDR(port, ATMEL_US_TXRDY); - tasklet_schedule(&atmel_port->tasklet); + if (atmel_use_dma_tx(port)) { + /* PDC transmit */ + if (pending & (ATMEL_US_ENDTX | ATMEL_US_TXBUFE)) { + UART_PUT_IDR(port, ATMEL_US_ENDTX | ATMEL_US_TXBUFE); + tasklet_schedule(&atmel_port->tasklet); + } + } else { + /* Interrupt transmit */ + if (pending & ATMEL_US_TXRDY) { + UART_PUT_IDR(port, ATMEL_US_TXRDY); + tasklet_schedule(&atmel_port->tasklet); + } } } @@ -417,20 +532,63 @@ static irqreturn_t atmel_interrupt(int irq, void *dev_id) struct uart_port *port = dev_id; unsigned int status, pending, pass_counter = 0; - status = UART_GET_CSR(port); - pending = status & UART_GET_IMR(port); - while (pending) { + do { + status = UART_GET_CSR(port); + pending = status & UART_GET_IMR(port); + if (!pending) + break; + atmel_handle_receive(port, pending); atmel_handle_status(port, pending, status); atmel_handle_transmit(port, pending); + } while (pass_counter++ < ATMEL_ISR_PASS_LIMIT); - if (pass_counter++ > ATMEL_ISR_PASS_LIMIT) - break; + return IRQ_HANDLED; +} - status = UART_GET_CSR(port); - pending = status & UART_GET_IMR(port); +/* + * Called from tasklet with ENDTX and TXBUFE interrupts disabled. + */ +static void atmel_tx_dma(struct uart_port *port) +{ + struct atmel_uart_port *atmel_port = (struct atmel_uart_port *)port; + struct circ_buf *xmit = &port->info->xmit; + struct atmel_dma_buffer *pdc = &atmel_port->pdc_tx; + int count; + + xmit->tail += pdc->ofs; + xmit->tail &= UART_XMIT_SIZE - 1; + + port->icount.tx += pdc->ofs; + pdc->ofs = 0; + + if (!uart_circ_empty(xmit)) { + /* more to transmit - setup next transfer */ + + /* disable PDC transmit */ + UART_PUT_PTCR(port, ATMEL_PDC_TXTDIS); + dma_sync_single_for_device(port->dev, + pdc->dma_addr, + pdc->dma_size, + DMA_TO_DEVICE); + + count = CIRC_CNT_TO_END(xmit->head, xmit->tail, UART_XMIT_SIZE); + pdc->ofs = count; + + UART_PUT_TPR(port, pdc->dma_addr + xmit->tail); + UART_PUT_TCR(port, count); + /* re-enable PDC transmit and interrupts */ + UART_PUT_PTCR(port, ATMEL_PDC_TXTEN); + UART_PUT_IER(port, ATMEL_US_ENDTX | ATMEL_US_TXBUFE); + } else { + /* nothing left to transmit - disable the transmitter */ + + /* disable PDC transmit */ + UART_PUT_PTCR(port, ATMEL_PDC_TXTDIS); } - return IRQ_HANDLED; + + if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS) + uart_write_wakeup(port); } static void atmel_rx_from_ring(struct uart_port *port) @@ -501,6 +659,82 @@ static void atmel_rx_from_ring(struct uart_port *port) spin_lock(&port->lock); } +static void atmel_rx_from_dma(struct uart_port *port) +{ + struct atmel_uart_port *atmel_port = (struct atmel_uart_port *)port; + struct tty_struct *tty = port->info->tty; + struct atmel_dma_buffer *pdc; + int rx_idx = atmel_port->pdc_rx_idx; + unsigned int head; + unsigned int tail; + unsigned int count; + + do { + /* Reset the UART timeout early so that we don't miss one */ + UART_PUT_CR(port, ATMEL_US_STTTO); + + pdc = &atmel_port->pdc_rx[rx_idx]; + head = UART_GET_RPR(port) - pdc->dma_addr; + tail = pdc->ofs; + + /* If the PDC has switched buffers, RPR won't contain + * any address within the current buffer. Since head + * is unsigned, we just need a one-way comparison to + * find out. + * + * In this case, we just need to consume the entire + * buffer and resubmit it for DMA. This will clear the + * ENDRX bit as well, so that we can safely re-enable + * all interrupts below. + */ + head = min(head, pdc->dma_size); + + if (likely(head != tail)) { + dma_sync_single_for_cpu(port->dev, pdc->dma_addr, + pdc->dma_size, DMA_FROM_DEVICE); + + /* + * head will only wrap around when we recycle + * the DMA buffer, and when that happens, we + * explicitly set tail to 0. So head will + * always be greater than tail. + */ + count = head - tail; + + tty_insert_flip_string(tty, pdc->buf + pdc->ofs, count); + + dma_sync_single_for_device(port->dev, pdc->dma_addr, + pdc->dma_size, DMA_FROM_DEVICE); + + port->icount.rx += count; + pdc->ofs = head; + } + + /* + * If the current buffer is full, we need to check if + * the next one contains any additional data. + */ + if (head >= pdc->dma_size) { + pdc->ofs = 0; + UART_PUT_RNPR(port, pdc->dma_addr); + UART_PUT_RNCR(port, pdc->dma_size); + + rx_idx = !rx_idx; + atmel_port->pdc_rx_idx = rx_idx; + } + } while (head >= pdc->dma_size); + + /* + * Drop the lock here since it might end up calling + * uart_start(), which takes the lock. + */ + spin_unlock(&port->lock); + tty_flip_buffer_push(tty); + spin_lock(&port->lock); + + UART_PUT_IER(port, ATMEL_US_ENDRX | ATMEL_US_TIMEOUT); +} + /* * tasklet handling tty stuff outside the interrupt handler. */ @@ -514,7 +748,10 @@ static void atmel_tasklet_func(unsigned long data) /* The interrupt handler does not take the lock */ spin_lock(&port->lock); - atmel_tx_chars(port); + if (atmel_use_dma_tx(port)) + atmel_tx_dma(port); + else + atmel_tx_chars(port); status = atmel_port->irq_status; status_change = status ^ atmel_port->irq_status_prev; @@ -536,7 +773,10 @@ static void atmel_tasklet_func(unsigned long data) atmel_port->irq_status_prev = status; } - atmel_rx_from_ring(port); + if (atmel_use_dma_rx(port)) + atmel_rx_from_dma(port); + else + atmel_rx_from_ring(port); spin_unlock(&port->lock); } @@ -546,6 +786,7 @@ static void atmel_tasklet_func(unsigned long data) */ static int atmel_startup(struct uart_port *port) { + struct atmel_uart_port *atmel_port = (struct atmel_uart_port *)port; int retval; /* @@ -566,6 +807,56 @@ static int atmel_startup(struct uart_port *port) } /* + * Initialize DMA (if necessary) + */ + if (atmel_use_dma_rx(port)) { + int i; + + for (i = 0; i < 2; i++) { + struct atmel_dma_buffer *pdc = &atmel_port->pdc_rx[i]; + + pdc->buf = kmalloc(PDC_BUFFER_SIZE, GFP_KERNEL); + if (pdc->buf == NULL) { + if (i != 0) { + dma_unmap_single(port->dev, + atmel_port->pdc_rx[0].dma_addr, + PDC_BUFFER_SIZE, + DMA_FROM_DEVICE); + kfree(atmel_port->pdc_rx[0].buf); + } + free_irq(port->irq, port); + return -ENOMEM; + } + pdc->dma_addr = dma_map_single(port->dev, + pdc->buf, + PDC_BUFFER_SIZE, + DMA_FROM_DEVICE); + pdc->dma_size = PDC_BUFFER_SIZE; + pdc->ofs = 0; + } + + atmel_port->pdc_rx_idx = 0; + + UART_PUT_RPR(port, atmel_port->pdc_rx[0].dma_addr); + UART_PUT_RCR(port, PDC_BUFFER_SIZE); + + UART_PUT_RNPR(port, atmel_port->pdc_rx[1].dma_addr); + UART_PUT_RNCR(port, PDC_BUFFER_SIZE); + } + if (atmel_use_dma_tx(port)) { + struct atmel_dma_buffer *pdc = &atmel_port->pdc_tx; + struct circ_buf *xmit = &port->info->xmit; + + pdc->buf = xmit->buf; + pdc->dma_addr = dma_map_single(port->dev, + pdc->buf, + UART_XMIT_SIZE, + DMA_TO_DEVICE); + pdc->dma_size = UART_XMIT_SIZE; + pdc->ofs = 0; + } + + /* * If there is a specific "open" function (to register * control line interrupts) */ @@ -584,8 +875,18 @@ static int atmel_startup(struct uart_port *port) /* enable xmit & rcvr */ UART_PUT_CR(port, ATMEL_US_TXEN | ATMEL_US_RXEN); - /* enable receive only */ - UART_PUT_IER(port, ATMEL_US_RXRDY); + if (atmel_use_dma_rx(port)) { + /* set UART timeout */ + UART_PUT_RTOR(port, PDC_RX_TIMEOUT); + UART_PUT_CR(port, ATMEL_US_STTTO); + + UART_PUT_IER(port, ATMEL_US_ENDRX | ATMEL_US_TIMEOUT); + /* enable PDC controller */ + UART_PUT_PTCR(port, ATMEL_PDC_RXTEN); + } else { + /* enable receive only */ + UART_PUT_IER(port, ATMEL_US_RXRDY); + } return 0; } @@ -595,6 +896,38 @@ static int atmel_startup(struct uart_port *port) */ static void atmel_shutdown(struct uart_port *port) { + struct atmel_uart_port *atmel_port = (struct atmel_uart_port *)port; + /* + * Ensure everything is stopped. + */ + atmel_stop_rx(port); + atmel_stop_tx(port); + + /* + * Shut-down the DMA. + */ + if (atmel_use_dma_rx(port)) { + int i; + + for (i = 0; i < 2; i++) { + struct atmel_dma_buffer *pdc = &atmel_port->pdc_rx[i]; + + dma_unmap_single(port->dev, + pdc->dma_addr, + pdc->dma_size, + DMA_FROM_DEVICE); + kfree(pdc->buf); + } + } + if (atmel_use_dma_tx(port)) { + struct atmel_dma_buffer *pdc = &atmel_port->pdc_tx; + + dma_unmap_single(port->dev, + pdc->dma_addr, + pdc->dma_size, + DMA_TO_DEVICE); + } + /* * Disable all interrupts, port and break condition. */ @@ -706,6 +1039,10 @@ static void atmel_set_termios(struct uart_port *port, struct ktermios *termios, if (termios->c_iflag & (BRKINT | PARMRK)) port->read_status_mask |= ATMEL_US_RXBRK; + if (atmel_use_dma_rx(port)) + /* need to enable error interrupts */ + UART_PUT_IER(port, port->read_status_mask); + /* * Characters to ignore */ @@ -891,6 +1228,11 @@ static void __devinit atmel_init_port(struct atmel_uart_port *atmel_port, clk_enable(atmel_port->clk); port->uartclk = clk_get_rate(atmel_port->clk); } + + atmel_port->use_dma_rx = data->use_dma_rx; + atmel_port->use_dma_tx = data->use_dma_tx; + if (atmel_use_dma_tx(port)) + port->fifosize = PDC_BUFFER_SIZE; } /* @@ -1125,11 +1467,13 @@ static int __devinit atmel_serial_probe(struct platform_device *pdev) port = &atmel_ports[pdev->id]; atmel_init_port(port, pdev); - ret = -ENOMEM; - data = kmalloc(ATMEL_SERIAL_RINGSIZE, GFP_KERNEL); - if (!data) - goto err_alloc_ring; - port->rx_ring.buf = data; + if (!atmel_use_dma_rx(&port->uart)) { + ret = -ENOMEM; + data = kmalloc(ATMEL_SERIAL_RINGSIZE, GFP_KERNEL); + if (!data) + goto err_alloc_ring; + port->rx_ring.buf = data; + } ret = uart_add_one_port(&atmel_uart, &port->uart); if (ret) |