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atmel_serial.c
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/*
* linux/drivers/char/atmel_serial.c
*
* Driver for Atmel AT91 / AT32 Serial ports
* Copyright (C) 2003 Rick Bronson
*
* 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
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*
*/
#include <linux/module.h>
#include <linux/tty.h>
#include <linux/ioport.h>
#include <linux/slab.h>
#include <linux/init.h>
#include <linux/serial.h>
#include <linux/clk.h>
#include <linux/console.h>
#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>
#include <linux/uaccess.h>
#include <asm/io.h>
#include <asm/ioctls.h>
#include <asm/mach/serial_at91.h>
#include <mach/board.h>
#ifdef CONFIG_ARM
#include <mach/cpu.h>
#include <mach/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
#include <linux/serial_core.h>
static void atmel_start_rx(struct uart_port *port);
static void atmel_stop_rx(struct uart_port *port);
#ifdef CONFIG_SERIAL_ATMEL_TTYAT
/* Use device name ttyAT, major 204 and minor 154-169. This is necessary if we
* should coexist with the 8250 driver, such as if we have an external 16C550
* UART. */
#define SERIAL_ATMEL_MAJOR 204
#define MINOR_START 154
#define ATMEL_DEVICENAME "ttyAT"
#else
/* Use device name ttyS, major 4, minor 64-68. This is the usual serial port
* name, but it is legally reserved for the 8250 driver. */
#define SERIAL_ATMEL_MAJOR TTY_MAJOR
#define MINOR_START 64
#define ATMEL_DEVICENAME "ttyS"
#endif
#define ATMEL_ISR_PASS_LIMIT 256
/* UART registers. CR is write-only, hence no GET macro */
#define UART_PUT_CR(port,v) __raw_writel(v, (port)->membase + ATMEL_US_CR)
#define UART_GET_MR(port) __raw_readl((port)->membase + ATMEL_US_MR)
#define UART_PUT_MR(port,v) __raw_writel(v, (port)->membase + ATMEL_US_MR)
#define UART_PUT_IER(port,v) __raw_writel(v, (port)->membase + ATMEL_US_IER)
#define UART_PUT_IDR(port,v) __raw_writel(v, (port)->membase + ATMEL_US_IDR)
#define UART_GET_IMR(port) __raw_readl((port)->membase + ATMEL_US_IMR)
#define UART_GET_CSR(port) __raw_readl((port)->membase + ATMEL_US_CSR)
#define UART_GET_CHAR(port) __raw_readl((port)->membase + ATMEL_US_RHR)
#define UART_PUT_CHAR(port,v) __raw_writel(v, (port)->membase + ATMEL_US_THR)
#define UART_GET_BRGR(port) __raw_readl((port)->membase + ATMEL_US_BRGR)
#define UART_PUT_BRGR(port,v) __raw_writel(v, (port)->membase + ATMEL_US_BRGR)
#define UART_PUT_RTOR(port,v) __raw_writel(v, (port)->membase + ATMEL_US_RTOR)
#define UART_PUT_TTGR(port, v) __raw_writel(v, (port)->membase + ATMEL_US_TTGR)
/* PDC registers */
#define UART_PUT_PTCR(port,v) __raw_writel(v, (port)->membase + ATMEL_PDC_PTCR)
#define UART_GET_PTSR(port) __raw_readl((port)->membase + ATMEL_PDC_PTSR)
#define UART_PUT_RPR(port,v) __raw_writel(v, (port)->membase + ATMEL_PDC_RPR)
#define UART_GET_RPR(port) __raw_readl((port)->membase + ATMEL_PDC_RPR)
#define UART_PUT_RCR(port,v) __raw_writel(v, (port)->membase + ATMEL_PDC_RCR)
#define UART_PUT_RNPR(port,v) __raw_writel(v, (port)->membase + ATMEL_PDC_RNPR)
#define UART_PUT_RNCR(port,v) __raw_writel(v, (port)->membase + ATMEL_PDC_RNCR)
#define UART_PUT_TPR(port,v) __raw_writel(v, (port)->membase + ATMEL_PDC_TPR)
#define UART_PUT_TCR(port,v) __raw_writel(v, (port)->membase + ATMEL_PDC_TCR)
#define UART_GET_TCR(port) __raw_readl((port)->membase + ATMEL_PDC_TCR)
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;
};
#define ATMEL_SERIAL_RINGSIZE 1024
/*
* We wrap our port structure around the generic uart_port.
*/
struct atmel_uart_port {
struct uart_port uart; /* uart */
struct clk *clk; /* uart clock */
int may_wakeup; /* cached value of device_may_wakeup for times we need to disable it */
u32 backup_imr; /* IMR saved during suspend */
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;
struct circ_buf rx_ring;
struct serial_rs485 rs485; /* rs485 settings */
unsigned int tx_done_mask;
};
static struct atmel_uart_port atmel_ports[ATMEL_MAX_UART];
#ifdef SUPPORT_SYSRQ
static struct console atmel_console;
#endif
static inline struct atmel_uart_port *
to_atmel_uart_port(struct uart_port *uart)
{
return container_of(uart, struct atmel_uart_port, uart);
}
#ifdef CONFIG_SERIAL_ATMEL_PDC
static bool atmel_use_dma_rx(struct uart_port *port)
{
struct atmel_uart_port *atmel_port = to_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 = to_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
/* Enable or disable the rs485 support */
void atmel_config_rs485(struct uart_port *port, struct serial_rs485 *rs485conf)
{
struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
unsigned int mode;
spin_lock(&port->lock);
/* Disable interrupts */
UART_PUT_IDR(port, atmel_port->tx_done_mask);
mode = UART_GET_MR(port);
/* Resetting serial mode to RS232 (0x0) */
mode &= ~ATMEL_US_USMODE;
atmel_port->rs485 = *rs485conf;
if (rs485conf->flags & SER_RS485_ENABLED) {
dev_dbg(port->dev, "Setting UART to RS485\n");
atmel_port->tx_done_mask = ATMEL_US_TXEMPTY;
if (rs485conf->flags & SER_RS485_RTS_AFTER_SEND)
UART_PUT_TTGR(port, rs485conf->delay_rts_after_send);
mode |= ATMEL_US_USMODE_RS485;
} else {
dev_dbg(port->dev, "Setting UART to RS232\n");
if (atmel_use_dma_tx(port))
atmel_port->tx_done_mask = ATMEL_US_ENDTX |
ATMEL_US_TXBUFE;
else
atmel_port->tx_done_mask = ATMEL_US_TXRDY;
}
UART_PUT_MR(port, mode);
/* Enable interrupts */
UART_PUT_IER(port, atmel_port->tx_done_mask);
spin_unlock(&port->lock);
}
/*
* Return TIOCSER_TEMT when transmitter FIFO and Shift register is empty.
*/
static u_int atmel_tx_empty(struct uart_port *port)
{
return (UART_GET_CSR(port) & ATMEL_US_TXEMPTY) ? TIOCSER_TEMT : 0;
}
/*
* Set state of the modem control output lines
*/
static void atmel_set_mctrl(struct uart_port *port, u_int mctrl)
{
unsigned int control = 0;
unsigned int mode;
struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
#ifdef CONFIG_ARCH_AT91RM9200
if (cpu_is_at91rm9200()) {
/*
* AT91RM9200 Errata #39: RTS0 is not internally connected
* to PA21. We need to drive the pin manually.
*/
if (port->mapbase == AT91RM9200_BASE_US0) {
if (mctrl & TIOCM_RTS)
at91_set_gpio_value(AT91_PIN_PA21, 0);
else
at91_set_gpio_value(AT91_PIN_PA21, 1);
}
}
#endif
if (mctrl & TIOCM_RTS)
control |= ATMEL_US_RTSEN;
else
control |= ATMEL_US_RTSDIS;
if (mctrl & TIOCM_DTR)
control |= ATMEL_US_DTREN;
else
control |= ATMEL_US_DTRDIS;
UART_PUT_CR(port, control);
/* Local loopback mode? */
mode = UART_GET_MR(port) & ~ATMEL_US_CHMODE;
if (mctrl & TIOCM_LOOP)
mode |= ATMEL_US_CHMODE_LOC_LOOP;
else
mode |= ATMEL_US_CHMODE_NORMAL;
/* Resetting serial mode to RS232 (0x0) */
mode &= ~ATMEL_US_USMODE;
if (atmel_port->rs485.flags & SER_RS485_ENABLED) {
dev_dbg(port->dev, "Setting UART to RS485\n");
if (atmel_port->rs485.flags & SER_RS485_RTS_AFTER_SEND)
UART_PUT_TTGR(port,
atmel_port->rs485.delay_rts_after_send);
mode |= ATMEL_US_USMODE_RS485;
} else {
dev_dbg(port->dev, "Setting UART to RS232\n");
}
UART_PUT_MR(port, mode);
}
/*
* Get state of the modem control input lines
*/
static u_int atmel_get_mctrl(struct uart_port *port)
{
unsigned int status, ret = 0;
status = UART_GET_CSR(port);
/*
* The control signals are active low.
*/
if (!(status & ATMEL_US_DCD))
ret |= TIOCM_CD;
if (!(status & ATMEL_US_CTS))
ret |= TIOCM_CTS;
if (!(status & ATMEL_US_DSR))
ret |= TIOCM_DSR;
if (!(status & ATMEL_US_RI))
ret |= TIOCM_RI;
return ret;
}
/*
* Stop transmitting.
*/
static void atmel_stop_tx(struct uart_port *port)
{
struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
if (atmel_use_dma_tx(port)) {
/* disable PDC transmit */
UART_PUT_PTCR(port, ATMEL_PDC_TXTDIS);
}
/* Disable interrupts */
UART_PUT_IDR(port, atmel_port->tx_done_mask);
if (atmel_port->rs485.flags & SER_RS485_ENABLED)
atmel_start_rx(port);
}
/*
* Start transmitting.
*/
static void atmel_start_tx(struct uart_port *port)
{
struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
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;
if (atmel_port->rs485.flags & SER_RS485_ENABLED)
atmel_stop_rx(port);
/* re-enable PDC transmit */
UART_PUT_PTCR(port, ATMEL_PDC_TXTEN);
}
/* Enable interrupts */
UART_PUT_IER(port, atmel_port->tx_done_mask);
}
/*
* start receiving - port is in process of being opened.
*/
static void atmel_start_rx(struct uart_port *port)
{
UART_PUT_CR(port, ATMEL_US_RSTSTA); /* reset status and receiver */
if (atmel_use_dma_rx(port)) {
/* enable PDC controller */
UART_PUT_IER(port, ATMEL_US_ENDRX | ATMEL_US_TIMEOUT |
port->read_status_mask);
UART_PUT_PTCR(port, ATMEL_PDC_RXTEN);
} else {
UART_PUT_IER(port, ATMEL_US_RXRDY);
}
}
/*
* Stop receiving - port is in process of being closed.
*/
static void atmel_stop_rx(struct uart_port *port)
{
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 |
port->read_status_mask);
} else {
UART_PUT_IDR(port, ATMEL_US_RXRDY);
}
}
/*
* Enable modem status interrupts
*/
static void atmel_enable_ms(struct uart_port *port)
{
UART_PUT_IER(port, ATMEL_US_RIIC | ATMEL_US_DSRIC
| ATMEL_US_DCDIC | ATMEL_US_CTSIC);
}
/*
* Control the transmission of a break signal
*/
static void atmel_break_ctl(struct uart_port *port, int break_state)
{
if (break_state != 0)
UART_PUT_CR(port, ATMEL_US_STTBRK); /* start break */
else
UART_PUT_CR(port, ATMEL_US_STPBRK); /* stop break */
}
/*
* Stores the incoming character in the ring buffer
*/
static void
atmel_buffer_rx_char(struct uart_port *port, unsigned int status,
unsigned int ch)
{
struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
struct circ_buf *ring = &atmel_port->rx_ring;
struct atmel_uart_char *c;
if (!CIRC_SPACE(ring->head, ring->tail, ATMEL_SERIAL_RINGSIZE))
/* Buffer overflow, ignore char */
return;
c = &((struct atmel_uart_char *)ring->buf)[ring->head];
c->status = status;
c->ch = ch;
/* Make sure the character is stored before we update head. */
smp_wmb();
ring->head = (ring->head + 1) & (ATMEL_SERIAL_RINGSIZE - 1);
}
/*
* 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)
{
struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
unsigned int status, ch;
status = UART_GET_CSR(port);
while (status & ATMEL_US_RXRDY) {
ch = UART_GET_CHAR(port);
/*
* note that the error handling code is
* out of the main execution path
*/
if (unlikely(status & (ATMEL_US_PARE | ATMEL_US_FRAME
| ATMEL_US_OVRE | ATMEL_US_RXBRK)
|| atmel_port->break_active)) {
/* clear error */
UART_PUT_CR(port, ATMEL_US_RSTSTA);
if (status & ATMEL_US_RXBRK
&& !atmel_port->break_active) {
atmel_port->break_active = 1;
UART_PUT_IER(port, ATMEL_US_RXBRK);
} else {
/*
* This is either the end-of-break
* condition or we've received at
* least one character without RXBRK
* being set. In both cases, the next
* RXBRK will indicate start-of-break.
*/
UART_PUT_IDR(port, ATMEL_US_RXBRK);
status &= ~ATMEL_US_RXBRK;
atmel_port->break_active = 0;
}
}
atmel_buffer_rx_char(port, status, ch);
status = UART_GET_CSR(port);
}
tasklet_schedule(&atmel_port->tasklet);
}
/*
* Transmit characters (called from tasklet with TXRDY interrupt
* disabled)
*/
static void atmel_tx_chars(struct uart_port *port)
{
struct circ_buf *xmit = &port->state->xmit;
struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
if (port->x_char && UART_GET_CSR(port) & atmel_port->tx_done_mask) {
UART_PUT_CHAR(port, port->x_char);
port->icount.tx++;
port->x_char = 0;
}
if (uart_circ_empty(xmit) || uart_tx_stopped(port))
return;
while (UART_GET_CSR(port) & atmel_port->tx_done_mask) {
UART_PUT_CHAR(port, xmit->buf[xmit->tail]);
xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
port->icount.tx++;
if (uart_circ_empty(xmit))
break;
}
if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
uart_write_wakeup(port);
if (!uart_circ_empty(xmit))
/* Enable interrupts */
UART_PUT_IER(port, atmel_port->tx_done_mask);
}
/*
* receive interrupt handler.
*/
static void
atmel_handle_receive(struct uart_port *port, unsigned int pending)
{
struct atmel_uart_port *atmel_port = to_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);
else if (pending & ATMEL_US_RXBRK) {
/*
* End of break detected. If it came along with a
* character, atmel_rx_chars will handle it.
*/
UART_PUT_CR(port, ATMEL_US_RSTSTA);
UART_PUT_IDR(port, ATMEL_US_RXBRK);
atmel_port->break_active = 0;
}
}
/*
* transmit interrupt handler. (Transmit is IRQF_NODELAY safe)
*/
static void
atmel_handle_transmit(struct uart_port *port, unsigned int pending)
{
struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
if (pending & atmel_port->tx_done_mask) {
/* Either PDC or interrupt transmission */
UART_PUT_IDR(port, atmel_port->tx_done_mask);
tasklet_schedule(&atmel_port->tasklet);
}
}
/*
* status flags interrupt handler.
*/
static void
atmel_handle_status(struct uart_port *port, unsigned int pending,
unsigned int status)
{
struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
if (pending & (ATMEL_US_RIIC | ATMEL_US_DSRIC | ATMEL_US_DCDIC
| ATMEL_US_CTSIC)) {
atmel_port->irq_status = status;
tasklet_schedule(&atmel_port->tasklet);
}
}
/*
* Interrupt handler
*/
static irqreturn_t atmel_interrupt(int irq, void *dev_id)
{
struct uart_port *port = dev_id;
unsigned int status, pending, pass_counter = 0;
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);
return pass_counter ? IRQ_HANDLED : IRQ_NONE;
}
/*
* Called from tasklet with ENDTX and TXBUFE interrupts disabled.
*/
static void atmel_tx_dma(struct uart_port *port)
{
struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
struct circ_buf *xmit = &port->state->xmit;
struct atmel_dma_buffer *pdc = &atmel_port->pdc_tx;
int count;
/* nothing left to transmit? */
if (UART_GET_TCR(port))
return;
xmit->tail += pdc->ofs;
xmit->tail &= UART_XMIT_SIZE - 1;
port->icount.tx += pdc->ofs;
pdc->ofs = 0;
/* more to transmit - setup next transfer */
/* disable PDC transmit */
UART_PUT_PTCR(port, ATMEL_PDC_TXTDIS);
if (!uart_circ_empty(xmit) && !uart_tx_stopped(port)) {
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 */
UART_PUT_PTCR(port, ATMEL_PDC_TXTEN);
/* Enable interrupts */
UART_PUT_IER(port, atmel_port->tx_done_mask);
} else {
if (atmel_port->rs485.flags & SER_RS485_ENABLED) {
/* DMA done, stop TX, start RX for RS485 */
atmel_start_rx(port);
}
}
if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
uart_write_wakeup(port);
}
static void atmel_rx_from_ring(struct uart_port *port)
{
struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
struct circ_buf *ring = &atmel_port->rx_ring;
unsigned int flg;
unsigned int status;
while (ring->head != ring->tail) {
struct atmel_uart_char c;
/* Make sure c is loaded after head. */
smp_rmb();
c = ((struct atmel_uart_char *)ring->buf)[ring->tail];
ring->tail = (ring->tail + 1) & (ATMEL_SERIAL_RINGSIZE - 1);
port->icount.rx++;
status = c.status;
flg = TTY_NORMAL;
/*
* note that the error handling code is
* out of the main execution path
*/
if (unlikely(status & (ATMEL_US_PARE | ATMEL_US_FRAME
| ATMEL_US_OVRE | ATMEL_US_RXBRK))) {
if (status & ATMEL_US_RXBRK) {
/* ignore side-effect */
status &= ~(ATMEL_US_PARE | ATMEL_US_FRAME);
port->icount.brk++;
if (uart_handle_break(port))
continue;
}
if (status & ATMEL_US_PARE)
port->icount.parity++;
if (status & ATMEL_US_FRAME)
port->icount.frame++;
if (status & ATMEL_US_OVRE)
port->icount.overrun++;
status &= port->read_status_mask;
if (status & ATMEL_US_RXBRK)
flg = TTY_BREAK;
else if (status & ATMEL_US_PARE)
flg = TTY_PARITY;
else if (status & ATMEL_US_FRAME)
flg = TTY_FRAME;
}
if (uart_handle_sysrq_char(port, c.ch))
continue;
uart_insert_char(port, status, ATMEL_US_OVRE, c.ch, flg);
}
/*
* Drop the lock here since it might end up calling
* uart_start(), which takes the lock.
*/
spin_unlock(&port->lock);
tty_flip_buffer_push(port->state->port.tty);
spin_lock(&port->lock);
}
static void atmel_rx_from_dma(struct uart_port *port)
{
struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
struct tty_struct *tty = port->state->port.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.
*/
static void atmel_tasklet_func(unsigned long data)
{
struct uart_port *port = (struct uart_port *)data;
struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
unsigned int status;
unsigned int status_change;
/* The interrupt handler does not take the lock */
spin_lock(&port->lock);
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;
if (status_change & (ATMEL_US_RI | ATMEL_US_DSR
| ATMEL_US_DCD | ATMEL_US_CTS)) {
/* TODO: All reads to CSR will clear these interrupts! */
if (status_change & ATMEL_US_RI)
port->icount.rng++;
if (status_change & ATMEL_US_DSR)
port->icount.dsr++;
if (status_change & ATMEL_US_DCD)
uart_handle_dcd_change(port, !(status & ATMEL_US_DCD));
if (status_change & ATMEL_US_CTS)
uart_handle_cts_change(port, !(status & ATMEL_US_CTS));
wake_up_interruptible(&port->state->port.delta_msr_wait);
atmel_port->irq_status_prev = status;
}
if (atmel_use_dma_rx(port))
atmel_rx_from_dma(port);
else
atmel_rx_from_ring(port);
spin_unlock(&port->lock);
}
/*
* Perform initialization and enable port for reception
*/
static int atmel_startup(struct uart_port *port)
{
struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
struct tty_struct *tty = port->state->port.tty;
int retval;
/*
* Ensure that no interrupts are enabled otherwise when
* request_irq() is called we could get stuck trying to
* handle an unexpected interrupt
*/
UART_PUT_IDR(port, -1);
/*
* Allocate the IRQ
*/
retval = request_irq(port->irq, atmel_interrupt, IRQF_SHARED,
tty ? tty->name : "atmel_serial", port);
if (retval) {
printk("atmel_serial: atmel_startup - Can't get irq\n");
return retval;
}
/*
* 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->state->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)
*/
if (atmel_open_hook) {
retval = atmel_open_hook(port);
if (retval) {
free_irq(port->irq, port);
return retval;
}
}
/* Save current CSR for comparison in atmel_tasklet_func() */
atmel_port->irq_status_prev = UART_GET_CSR(port);
atmel_port->irq_status = atmel_port->irq_status_prev;
/*
* Finally, enable the serial port
*/
UART_PUT_CR(port, ATMEL_US_RSTSTA | ATMEL_US_RSTRX);
/* 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;
}
/*