atmel_serial: add DMA support
This patch is based on the DMA-patch by Chip Coldwell for the AT91/AT32 serial USARTS, with some tweaks to make it apply neatly on top of the other patches in this series. The RX and TX code has been moved to a tasklet and reworked a bit. Instead of depending on the ENDRX and TIMEOUT bits in CSR, we simply grab as much data as we can from the DMA buffers. I think this closes a race where the ENDRX bit is set after we read CSR but before we read RPR, although I haven't confirmed this. Similarly, the two TX handlers (ENDTX and TXBUFE) have been combined into one. Since the current code only uses a single TX buffer, there's no point in handling those interrupts separately. This also fixes a DMA sync bug in the original patch. [linux@bohmer.net: rebased onto irq-splitup patch] [hskinnemoen@atmel.com: moved to tasklet, fixed dma bug, misc cleanups] [hskinnemoen@atmel.com: atmel_serial dma: Misc fixes and cleanups] Signed-off-by: Remy Bohmer <linux@bohmer.net> Signed-off-by: Haavard Skinnemoen <hskinnemoen@atmel.com> Cc: Andrew Victor <linux@maxim.org.za> Tested-by: Marc Pignat <marc.pignat@hevs.ch> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
parent
1ecc26bd27
commit
a66706158d
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@ -380,6 +380,21 @@ config SERIAL_ATMEL_CONSOLE
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console is the device which receives all kernel messages and
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warnings and which allows logins in single user mode).
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config SERIAL_ATMEL_PDC
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bool "Support DMA transfers on AT91 / AT32 serial port"
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depends on SERIAL_ATMEL
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default y
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help
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Say Y here if you wish to use the PDC to do DMA transfers to
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and from the Atmel AT91 / AT32 serial port. In order to
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actually use DMA transfers, make sure that the use_dma_tx
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and use_dma_rx members in the atmel_uart_data struct is set
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appropriately for each port.
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Note that break and error handling currently doesn't work
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properly when DMA is enabled. Make sure that ports where
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this matters don't use DMA.
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config SERIAL_ATMEL_TTYAT
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bool "Install as device ttyATn instead of ttySn"
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depends on SERIAL_ATMEL=y
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@ -7,6 +7,8 @@
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* Based on drivers/char/serial_sa1100.c, by Deep Blue Solutions Ltd.
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* Based on drivers/char/serial.c, by Linus Torvalds, Theodore Ts'o.
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*
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* DMA support added by Chip Coldwell.
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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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@ -33,6 +35,7 @@
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#include <linux/sysrq.h>
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#include <linux/tty_flip.h>
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#include <linux/platform_device.h>
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#include <linux/dma-mapping.h>
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#include <linux/atmel_pdc.h>
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#include <linux/atmel_serial.h>
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@ -46,6 +49,10 @@
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#include <asm/arch/gpio.h>
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#endif
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#define PDC_BUFFER_SIZE 512
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/* Revisit: We should calculate this based on the actual port settings */
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#define PDC_RX_TIMEOUT (3 * 10) /* 3 bytes */
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#if defined(CONFIG_SERIAL_ATMEL_CONSOLE) && defined(CONFIG_MAGIC_SYSRQ)
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#define SUPPORT_SYSRQ
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#endif
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@ -103,6 +110,13 @@
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static int (*atmel_open_hook)(struct uart_port *);
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static void (*atmel_close_hook)(struct uart_port *);
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struct atmel_dma_buffer {
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unsigned char *buf;
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dma_addr_t dma_addr;
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unsigned int dma_size;
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unsigned int ofs;
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};
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struct atmel_uart_char {
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u16 status;
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u16 ch;
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@ -119,6 +133,13 @@ struct atmel_uart_port {
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unsigned short suspended; /* is port suspended? */
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int break_active; /* break being received */
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short use_dma_rx; /* enable PDC receiver */
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short pdc_rx_idx; /* current PDC RX buffer */
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struct atmel_dma_buffer pdc_rx[2]; /* PDC receier */
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short use_dma_tx; /* enable PDC transmitter */
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struct atmel_dma_buffer pdc_tx; /* PDC transmitter */
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struct tasklet_struct tasklet;
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unsigned int irq_status;
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unsigned int irq_status_prev;
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@ -132,6 +153,32 @@ static struct atmel_uart_port atmel_ports[ATMEL_MAX_UART];
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static struct console atmel_console;
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#endif
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#ifdef CONFIG_SERIAL_ATMEL_PDC
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static bool atmel_use_dma_rx(struct uart_port *port)
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{
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struct atmel_uart_port *atmel_port = (struct atmel_uart_port *)port;
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return atmel_port->use_dma_rx;
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}
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static bool atmel_use_dma_tx(struct uart_port *port)
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{
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struct atmel_uart_port *atmel_port = (struct atmel_uart_port *)port;
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return atmel_port->use_dma_tx;
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}
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#else
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static bool atmel_use_dma_rx(struct uart_port *port)
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{
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return false;
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}
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static bool atmel_use_dma_tx(struct uart_port *port)
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{
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return false;
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}
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#endif
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/*
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* Return TIOCSER_TEMT when transmitter FIFO and Shift register is empty.
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*/
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@ -213,6 +260,11 @@ static u_int atmel_get_mctrl(struct uart_port *port)
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*/
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static void atmel_stop_tx(struct uart_port *port)
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{
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if (atmel_use_dma_tx(port)) {
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/* disable PDC transmit */
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UART_PUT_PTCR(port, ATMEL_PDC_TXTDIS);
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UART_PUT_IDR(port, ATMEL_US_ENDTX | ATMEL_US_TXBUFE);
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} else
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UART_PUT_IDR(port, ATMEL_US_TXRDY);
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}
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@ -221,6 +273,16 @@ static void atmel_stop_tx(struct uart_port *port)
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*/
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static void atmel_start_tx(struct uart_port *port)
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{
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if (atmel_use_dma_tx(port)) {
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if (UART_GET_PTSR(port) & ATMEL_PDC_TXTEN)
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/* The transmitter is already running. Yes, we
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really need this.*/
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return;
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UART_PUT_IER(port, ATMEL_US_ENDTX | ATMEL_US_TXBUFE);
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/* re-enable PDC transmit */
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UART_PUT_PTCR(port, ATMEL_PDC_TXTEN);
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} else
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UART_PUT_IER(port, ATMEL_US_TXRDY);
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}
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@ -229,6 +291,11 @@ static void atmel_start_tx(struct uart_port *port)
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*/
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static void atmel_stop_rx(struct uart_port *port)
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{
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if (atmel_use_dma_rx(port)) {
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/* disable PDC receive */
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UART_PUT_PTCR(port, ATMEL_PDC_RXTDIS);
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UART_PUT_IDR(port, ATMEL_US_ENDRX | ATMEL_US_TIMEOUT);
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} else
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UART_PUT_IDR(port, ATMEL_US_RXRDY);
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}
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@ -277,6 +344,27 @@ atmel_buffer_rx_char(struct uart_port *port, unsigned int status,
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ring->head = (ring->head + 1) & (ATMEL_SERIAL_RINGSIZE - 1);
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}
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/*
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* Deal with parity, framing and overrun errors.
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*/
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static void atmel_pdc_rxerr(struct uart_port *port, unsigned int status)
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{
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/* clear error */
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UART_PUT_CR(port, ATMEL_US_RSTSTA);
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if (status & ATMEL_US_RXBRK) {
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/* ignore side-effect */
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status &= ~(ATMEL_US_PARE | ATMEL_US_FRAME);
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port->icount.brk++;
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}
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if (status & ATMEL_US_PARE)
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port->icount.parity++;
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if (status & ATMEL_US_FRAME)
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port->icount.frame++;
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if (status & ATMEL_US_OVRE)
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port->icount.overrun++;
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}
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/*
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* Characters received (called from interrupt handler)
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*/
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@ -364,6 +452,25 @@ atmel_handle_receive(struct uart_port *port, unsigned int pending)
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{
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struct atmel_uart_port *atmel_port = (struct atmel_uart_port *)port;
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if (atmel_use_dma_rx(port)) {
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/*
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* PDC receive. Just schedule the tasklet and let it
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* figure out the details.
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*
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* TODO: We're not handling error flags correctly at
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* the moment.
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*/
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if (pending & (ATMEL_US_ENDRX | ATMEL_US_TIMEOUT)) {
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UART_PUT_IDR(port, (ATMEL_US_ENDRX
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| ATMEL_US_TIMEOUT));
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tasklet_schedule(&atmel_port->tasklet);
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}
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if (pending & (ATMEL_US_RXBRK | ATMEL_US_OVRE |
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ATMEL_US_FRAME | ATMEL_US_PARE))
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atmel_pdc_rxerr(port, pending);
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}
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/* Interrupt receive */
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if (pending & ATMEL_US_RXRDY)
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atmel_rx_chars(port);
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@ -386,11 +493,19 @@ atmel_handle_transmit(struct uart_port *port, unsigned int pending)
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{
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struct atmel_uart_port *atmel_port = (struct atmel_uart_port *)port;
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if (atmel_use_dma_tx(port)) {
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/* PDC transmit */
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if (pending & (ATMEL_US_ENDTX | ATMEL_US_TXBUFE)) {
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UART_PUT_IDR(port, ATMEL_US_ENDTX | ATMEL_US_TXBUFE);
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tasklet_schedule(&atmel_port->tasklet);
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}
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} else {
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/* Interrupt transmit */
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if (pending & ATMEL_US_TXRDY) {
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UART_PUT_IDR(port, ATMEL_US_TXRDY);
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tasklet_schedule(&atmel_port->tasklet);
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}
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}
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}
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/*
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@ -417,22 +532,65 @@ static irqreturn_t atmel_interrupt(int irq, void *dev_id)
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struct uart_port *port = dev_id;
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unsigned int status, pending, pass_counter = 0;
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do {
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status = UART_GET_CSR(port);
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pending = status & UART_GET_IMR(port);
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while (pending) {
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if (!pending)
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break;
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atmel_handle_receive(port, pending);
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atmel_handle_status(port, pending, status);
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atmel_handle_transmit(port, pending);
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} while (pass_counter++ < ATMEL_ISR_PASS_LIMIT);
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if (pass_counter++ > ATMEL_ISR_PASS_LIMIT)
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break;
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status = UART_GET_CSR(port);
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pending = status & UART_GET_IMR(port);
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}
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return IRQ_HANDLED;
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}
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/*
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* Called from tasklet with ENDTX and TXBUFE interrupts disabled.
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*/
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static void atmel_tx_dma(struct uart_port *port)
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{
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struct atmel_uart_port *atmel_port = (struct atmel_uart_port *)port;
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struct circ_buf *xmit = &port->info->xmit;
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struct atmel_dma_buffer *pdc = &atmel_port->pdc_tx;
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int count;
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xmit->tail += pdc->ofs;
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xmit->tail &= UART_XMIT_SIZE - 1;
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port->icount.tx += pdc->ofs;
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pdc->ofs = 0;
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if (!uart_circ_empty(xmit)) {
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/* more to transmit - setup next transfer */
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/* disable PDC transmit */
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UART_PUT_PTCR(port, ATMEL_PDC_TXTDIS);
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dma_sync_single_for_device(port->dev,
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pdc->dma_addr,
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pdc->dma_size,
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DMA_TO_DEVICE);
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count = CIRC_CNT_TO_END(xmit->head, xmit->tail, UART_XMIT_SIZE);
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pdc->ofs = count;
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UART_PUT_TPR(port, pdc->dma_addr + xmit->tail);
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UART_PUT_TCR(port, count);
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/* re-enable PDC transmit and interrupts */
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UART_PUT_PTCR(port, ATMEL_PDC_TXTEN);
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UART_PUT_IER(port, ATMEL_US_ENDTX | ATMEL_US_TXBUFE);
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} else {
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/* nothing left to transmit - disable the transmitter */
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/* disable PDC transmit */
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UART_PUT_PTCR(port, ATMEL_PDC_TXTDIS);
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}
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if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
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uart_write_wakeup(port);
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}
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static void atmel_rx_from_ring(struct uart_port *port)
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{
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struct atmel_uart_port *atmel_port = (struct atmel_uart_port *)port;
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@ -501,6 +659,82 @@ static void atmel_rx_from_ring(struct uart_port *port)
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spin_lock(&port->lock);
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}
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static void atmel_rx_from_dma(struct uart_port *port)
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{
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struct atmel_uart_port *atmel_port = (struct atmel_uart_port *)port;
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struct tty_struct *tty = port->info->tty;
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struct atmel_dma_buffer *pdc;
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int rx_idx = atmel_port->pdc_rx_idx;
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unsigned int head;
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unsigned int tail;
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unsigned int count;
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do {
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/* Reset the UART timeout early so that we don't miss one */
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UART_PUT_CR(port, ATMEL_US_STTTO);
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pdc = &atmel_port->pdc_rx[rx_idx];
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head = UART_GET_RPR(port) - pdc->dma_addr;
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tail = pdc->ofs;
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/* If the PDC has switched buffers, RPR won't contain
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* any address within the current buffer. Since head
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* is unsigned, we just need a one-way comparison to
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* find out.
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*
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* In this case, we just need to consume the entire
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* buffer and resubmit it for DMA. This will clear the
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* ENDRX bit as well, so that we can safely re-enable
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* all interrupts below.
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*/
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head = min(head, pdc->dma_size);
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if (likely(head != tail)) {
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dma_sync_single_for_cpu(port->dev, pdc->dma_addr,
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pdc->dma_size, DMA_FROM_DEVICE);
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/*
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* head will only wrap around when we recycle
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* the DMA buffer, and when that happens, we
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* explicitly set tail to 0. So head will
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* always be greater than tail.
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*/
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count = head - tail;
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tty_insert_flip_string(tty, pdc->buf + pdc->ofs, count);
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dma_sync_single_for_device(port->dev, pdc->dma_addr,
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pdc->dma_size, DMA_FROM_DEVICE);
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port->icount.rx += count;
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pdc->ofs = head;
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}
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/*
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* If the current buffer is full, we need to check if
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* the next one contains any additional data.
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*/
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if (head >= pdc->dma_size) {
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pdc->ofs = 0;
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UART_PUT_RNPR(port, pdc->dma_addr);
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UART_PUT_RNCR(port, pdc->dma_size);
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rx_idx = !rx_idx;
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atmel_port->pdc_rx_idx = rx_idx;
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}
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} while (head >= pdc->dma_size);
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/*
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* Drop the lock here since it might end up calling
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* uart_start(), which takes the lock.
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*/
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spin_unlock(&port->lock);
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tty_flip_buffer_push(tty);
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spin_lock(&port->lock);
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UART_PUT_IER(port, ATMEL_US_ENDRX | ATMEL_US_TIMEOUT);
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}
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/*
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* tasklet handling tty stuff outside the interrupt handler.
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*/
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@ -514,6 +748,9 @@ static void atmel_tasklet_func(unsigned long data)
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/* The interrupt handler does not take the lock */
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spin_lock(&port->lock);
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if (atmel_use_dma_tx(port))
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atmel_tx_dma(port);
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else
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atmel_tx_chars(port);
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status = atmel_port->irq_status;
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@ -536,6 +773,9 @@ static void atmel_tasklet_func(unsigned long data)
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atmel_port->irq_status_prev = status;
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}
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if (atmel_use_dma_rx(port))
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atmel_rx_from_dma(port);
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else
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atmel_rx_from_ring(port);
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spin_unlock(&port->lock);
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@ -546,6 +786,7 @@ static void atmel_tasklet_func(unsigned long data)
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*/
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static int atmel_startup(struct uart_port *port)
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{
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struct atmel_uart_port *atmel_port = (struct atmel_uart_port *)port;
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int retval;
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/*
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@ -565,6 +806,56 @@ static int atmel_startup(struct uart_port *port)
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return retval;
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}
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/*
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* Initialize DMA (if necessary)
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*/
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if (atmel_use_dma_rx(port)) {
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int i;
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for (i = 0; i < 2; i++) {
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struct atmel_dma_buffer *pdc = &atmel_port->pdc_rx[i];
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pdc->buf = kmalloc(PDC_BUFFER_SIZE, GFP_KERNEL);
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if (pdc->buf == NULL) {
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if (i != 0) {
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dma_unmap_single(port->dev,
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atmel_port->pdc_rx[0].dma_addr,
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PDC_BUFFER_SIZE,
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DMA_FROM_DEVICE);
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kfree(atmel_port->pdc_rx[0].buf);
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}
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free_irq(port->irq, port);
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return -ENOMEM;
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}
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pdc->dma_addr = dma_map_single(port->dev,
|
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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);
|
||||
|
||||
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);
|
||||
|
||||
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)
|
||||
|
|
Loading…
Reference in a new issue