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OpenCloudOS-Kernel/drivers/tty/serial/arc_uart.c

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/*
* ARC On-Chip(fpga) UART Driver
*
* Copyright (C) 2010-2012 Synopsys, Inc. (www.synopsys.com)
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*
* vineetg: July 10th 2012
* -Decoupled the driver from arch/arc
* +Using platform_get_resource() for irq/membase (thx to bfin_uart.c)
* +Using early_platform_xxx() for early console (thx to mach-shmobile/xxx)
*
* Vineetg: Aug 21st 2010
* -Is uart_tx_stopped() not done in tty write path as it has already been
* taken care of, in serial core
*
* Vineetg: Aug 18th 2010
* -New Serial Core based ARC UART driver
* -Derived largely from blackfin driver albiet with some major tweaks
*
* TODO:
* -check if sysreq works
*/
#if defined(CONFIG_SERIAL_ARC_CONSOLE) && defined(CONFIG_MAGIC_SYSRQ)
#define SUPPORT_SYSRQ
#endif
#include <linux/module.h>
#include <linux/serial.h>
#include <linux/console.h>
#include <linux/sysrq.h>
#include <linux/platform_device.h>
#include <linux/tty.h>
#include <linux/tty_flip.h>
#include <linux/serial_core.h>
#include <linux/io.h>
/*************************************
* ARC UART Hardware Specs
************************************/
#define ARC_UART_TX_FIFO_SIZE 1
/*
* UART Register set (this is not a Standards Compliant IP)
* Also each reg is Word aligned, but only 8 bits wide
*/
#define R_ID0 0
#define R_ID1 4
#define R_ID2 8
#define R_ID3 12
#define R_DATA 16
#define R_STS 20
#define R_BAUDL 24
#define R_BAUDH 28
/* Bits for UART Status Reg (R/W) */
#define RXIENB 0x04 /* Receive Interrupt Enable */
#define TXIENB 0x40 /* Transmit Interrupt Enable */
#define RXEMPTY 0x20 /* Receive FIFO Empty: No char receivede */
#define TXEMPTY 0x80 /* Transmit FIFO Empty, thus char can be written into */
#define RXFULL 0x08 /* Receive FIFO full */
#define RXFULL1 0x10 /* Receive FIFO has space for 1 char (tot space=4) */
#define RXFERR 0x01 /* Frame Error: Stop Bit not detected */
#define RXOERR 0x02 /* OverFlow Err: Char recv but RXFULL still set */
/* Uart bit fiddling helpers: lowest level */
#define RBASE(uart, reg) (uart->port.membase + reg)
#define UART_REG_SET(u, r, v) writeb((v), RBASE(u, r))
#define UART_REG_GET(u, r) readb(RBASE(u, r))
#define UART_REG_OR(u, r, v) UART_REG_SET(u, r, UART_REG_GET(u, r) | (v))
#define UART_REG_CLR(u, r, v) UART_REG_SET(u, r, UART_REG_GET(u, r) & ~(v))
/* Uart bit fiddling helpers: API level */
#define UART_SET_DATA(uart, val) UART_REG_SET(uart, R_DATA, val)
#define UART_GET_DATA(uart) UART_REG_GET(uart, R_DATA)
#define UART_SET_BAUDH(uart, val) UART_REG_SET(uart, R_BAUDH, val)
#define UART_SET_BAUDL(uart, val) UART_REG_SET(uart, R_BAUDL, val)
#define UART_CLR_STATUS(uart, val) UART_REG_CLR(uart, R_STS, val)
#define UART_GET_STATUS(uart) UART_REG_GET(uart, R_STS)
#define UART_ALL_IRQ_DISABLE(uart) UART_REG_CLR(uart, R_STS, RXIENB|TXIENB)
#define UART_RX_IRQ_DISABLE(uart) UART_REG_CLR(uart, R_STS, RXIENB)
#define UART_TX_IRQ_DISABLE(uart) UART_REG_CLR(uart, R_STS, TXIENB)
#define UART_ALL_IRQ_ENABLE(uart) UART_REG_OR(uart, R_STS, RXIENB|TXIENB)
#define UART_RX_IRQ_ENABLE(uart) UART_REG_OR(uart, R_STS, RXIENB)
#define UART_TX_IRQ_ENABLE(uart) UART_REG_OR(uart, R_STS, TXIENB)
#define ARC_SERIAL_DEV_NAME "ttyARC"
struct arc_uart_port {
struct uart_port port;
unsigned long baud;
int is_emulated; /* H/w vs. Instruction Set Simulator */
};
#define to_arc_port(uport) container_of(uport, struct arc_uart_port, port)
static struct arc_uart_port arc_uart_ports[CONFIG_SERIAL_ARC_NR_PORTS];
#ifdef CONFIG_SERIAL_ARC_CONSOLE
static struct console arc_console;
#endif
#define DRIVER_NAME "arc-uart"
static struct uart_driver arc_uart_driver = {
.owner = THIS_MODULE,
.driver_name = DRIVER_NAME,
.dev_name = ARC_SERIAL_DEV_NAME,
.major = 0,
.minor = 0,
.nr = CONFIG_SERIAL_ARC_NR_PORTS,
#ifdef CONFIG_SERIAL_ARC_CONSOLE
.cons = &arc_console,
#endif
};
static void arc_serial_stop_rx(struct uart_port *port)
{
struct arc_uart_port *uart = to_arc_port(port);
UART_RX_IRQ_DISABLE(uart);
}
static void arc_serial_stop_tx(struct uart_port *port)
{
struct arc_uart_port *uart = to_arc_port(port);
while (!(UART_GET_STATUS(uart) & TXEMPTY))
cpu_relax();
UART_TX_IRQ_DISABLE(uart);
}
/*
* Return TIOCSER_TEMT when transmitter is not busy.
*/
static unsigned int arc_serial_tx_empty(struct uart_port *port)
{
struct arc_uart_port *uart = to_arc_port(port);
unsigned int stat;
stat = UART_GET_STATUS(uart);
if (stat & TXEMPTY)
return TIOCSER_TEMT;
return 0;
}
/*
* Driver internal routine, used by both tty(serial core) as well as tx-isr
* -Called under spinlock in either cases
* -also tty->stopped / tty->hw_stopped has already been checked
* = by uart_start( ) before calling us
* = tx_ist checks that too before calling
*/
static void arc_serial_tx_chars(struct arc_uart_port *uart)
{
struct circ_buf *xmit = &uart->port.state->xmit;
int sent = 0;
unsigned char ch;
if (unlikely(uart->port.x_char)) {
UART_SET_DATA(uart, uart->port.x_char);
uart->port.icount.tx++;
uart->port.x_char = 0;
sent = 1;
} else if (xmit->tail != xmit->head) { /* TODO: uart_circ_empty */
ch = xmit->buf[xmit->tail];
xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
uart->port.icount.tx++;
while (!(UART_GET_STATUS(uart) & TXEMPTY))
cpu_relax();
UART_SET_DATA(uart, ch);
sent = 1;
}
/*
* If num chars in xmit buffer are too few, ask tty layer for more.
* By Hard ISR to schedule processing in software interrupt part
*/
if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
uart_write_wakeup(&uart->port);
if (sent)
UART_TX_IRQ_ENABLE(uart);
}
/*
* port is locked and interrupts are disabled
* uart_start( ) calls us under the port spinlock irqsave
*/
static void arc_serial_start_tx(struct uart_port *port)
{
struct arc_uart_port *uart = to_arc_port(port);
arc_serial_tx_chars(uart);
}
static void arc_serial_rx_chars(struct arc_uart_port *uart)
{
struct tty_struct *tty = tty_port_tty_get(&uart->port.state->port);
unsigned int status, ch, flg = 0;
if (!tty)
return;
/*
* UART has 4 deep RX-FIFO. Driver's recongnition of this fact
* is very subtle. Here's how ...
* Upon getting a RX-Intr, such that RX-EMPTY=0, meaning data available,
* driver reads the DATA Reg and keeps doing that in a loop, until
* RX-EMPTY=1. Multiple chars being avail, with a single Interrupt,
* before RX-EMPTY=0, implies some sort of buffering going on in the
* controller, which is indeed the Rx-FIFO.
*/
while (!((status = UART_GET_STATUS(uart)) & RXEMPTY)) {
ch = UART_GET_DATA(uart);
uart->port.icount.rx++;
if (unlikely(status & (RXOERR | RXFERR))) {
if (status & RXOERR) {
uart->port.icount.overrun++;
flg = TTY_OVERRUN;
UART_CLR_STATUS(uart, RXOERR);
}
if (status & RXFERR) {
uart->port.icount.frame++;
flg = TTY_FRAME;
UART_CLR_STATUS(uart, RXFERR);
}
} else
flg = TTY_NORMAL;
if (unlikely(uart_handle_sysrq_char(&uart->port, ch)))
goto done;
uart_insert_char(&uart->port, status, RXOERR, ch, flg);
done:
tty_flip_buffer_push(tty);
}
tty_kref_put(tty);
}
/*
* A note on the Interrupt handling state machine of this driver
*
* kernel printk writes funnel thru the console driver framework and in order
* to keep things simple as well as efficient, it writes to UART in polled
* mode, in one shot, and exits.
*
* OTOH, Userland output (via tty layer), uses interrupt based writes as there
* can be undeterministic delay between char writes.
*
* Thus Rx-interrupts are always enabled, while tx-interrupts are by default
* disabled.
*
* When tty has some data to send out, serial core calls driver's start_tx
* which
* -checks-if-tty-buffer-has-char-to-send
* -writes-data-to-uart
* -enable-tx-intr
*
* Once data bits are pushed out, controller raises the Tx-room-avail-Interrupt.
* The first thing Tx ISR does is disable further Tx interrupts (as this could
* be the last char to send, before settling down into the quiet polled mode).
* It then calls the exact routine used by tty layer write to send out any
* more char in tty buffer. In case of sending, it re-enables Tx-intr. In case
* of no data, it remains disabled.
* This is how the transmit state machine is dynamically switched on/off
*/
static irqreturn_t arc_serial_isr(int irq, void *dev_id)
{
struct arc_uart_port *uart = dev_id;
unsigned int status;
status = UART_GET_STATUS(uart);
/*
* Single IRQ for both Rx (data available) Tx (room available) Interrupt
* notifications from the UART Controller.
* To demultiplex between the two, we check the relevant bits
*/
if ((status & RXIENB) && !(status & RXEMPTY)) {
/* already in ISR, no need of xx_irqsave */
spin_lock(&uart->port.lock);
arc_serial_rx_chars(uart);
spin_unlock(&uart->port.lock);
}
if ((status & TXIENB) && (status & TXEMPTY)) {
/* Unconditionally disable further Tx-Interrupts.
* will be enabled by tx_chars() if needed.
*/
UART_TX_IRQ_DISABLE(uart);
spin_lock(&uart->port.lock);
if (!uart_tx_stopped(&uart->port))
arc_serial_tx_chars(uart);
spin_unlock(&uart->port.lock);
}
return IRQ_HANDLED;
}
static unsigned int arc_serial_get_mctrl(struct uart_port *port)
{
/*
* Pretend we have a Modem status reg and following bits are
* always set, to satify the serial core state machine
* (DSR) Data Set Ready
* (CTS) Clear To Send
* (CAR) Carrier Detect
*/
return TIOCM_CTS | TIOCM_DSR | TIOCM_CAR;
}
static void arc_serial_set_mctrl(struct uart_port *port, unsigned int mctrl)
{
/* MCR not present */
}
/* Enable Modem Status Interrupts */
static void arc_serial_enable_ms(struct uart_port *port)
{
/* MSR not present */
}
static void arc_serial_break_ctl(struct uart_port *port, int break_state)
{
/* ARC UART doesn't support sending Break signal */
}
static int arc_serial_startup(struct uart_port *port)
{
struct arc_uart_port *uart = to_arc_port(port);
/* Before we hook up the ISR, Disable all UART Interrupts */
UART_ALL_IRQ_DISABLE(uart);
if (request_irq(uart->port.irq, arc_serial_isr, 0, "arc uart rx-tx",
uart)) {
dev_warn(uart->port.dev, "Unable to attach ARC UART intr\n");
return -EBUSY;
}
UART_RX_IRQ_ENABLE(uart); /* Only Rx IRQ enabled to begin with */
return 0;
}
/* This is not really needed */
static void arc_serial_shutdown(struct uart_port *port)
{
struct arc_uart_port *uart = to_arc_port(port);
free_irq(uart->port.irq, uart);
}
static void
arc_serial_set_termios(struct uart_port *port, struct ktermios *new,
struct ktermios *old)
{
struct arc_uart_port *uart = to_arc_port(port);
unsigned int baud, uartl, uarth, hw_val;
unsigned long flags;
/*
* Use the generic handler so that any specially encoded baud rates
* such as SPD_xx flags or "%B0" can be handled
* Max Baud I suppose will not be more than current 115K * 4
* Formula for ARC UART is: hw-val = ((CLK/(BAUD*4)) -1)
* spread over two 8-bit registers
*/
baud = uart_get_baud_rate(port, new, old, 0, 460800);
hw_val = port->uartclk / (uart->baud * 4) - 1;
uartl = hw_val & 0xFF;
uarth = (hw_val >> 8) & 0xFF;
/*
* UART ISS(Instruction Set simulator) emulation has a subtle bug:
* A existing value of Baudh = 0 is used as a indication to startup
* it's internal state machine.
* Thus if baudh is set to 0, 2 times, it chokes.
* This happens with BAUD=115200 and the formaula above
* Until that is fixed, when running on ISS, we will set baudh to !0
*/
if (uart->is_emulated)
uarth = 1;
spin_lock_irqsave(&port->lock, flags);
UART_ALL_IRQ_DISABLE(uart);
UART_SET_BAUDL(uart, uartl);
UART_SET_BAUDH(uart, uarth);
UART_RX_IRQ_ENABLE(uart);
/*
* UART doesn't support Parity/Hardware Flow Control;
* Only supports 8N1 character size
*/
new->c_cflag &= ~(CMSPAR|CRTSCTS|CSIZE);
new->c_cflag |= CS8;
if (old)
tty_termios_copy_hw(new, old);
/* Don't rewrite B0 */
if (tty_termios_baud_rate(new))
tty_termios_encode_baud_rate(new, baud, baud);
uart_update_timeout(port, new->c_cflag, baud);
spin_unlock_irqrestore(&port->lock, flags);
}
static const char *arc_serial_type(struct uart_port *port)
{
struct arc_uart_port *uart = to_arc_port(port);
return uart->port.type == PORT_ARC ? DRIVER_NAME : NULL;
}
static void arc_serial_release_port(struct uart_port *port)
{
}
static int arc_serial_request_port(struct uart_port *port)
{
return 0;
}
/*
* Verify the new serial_struct (for TIOCSSERIAL).
*/
static int
arc_serial_verify_port(struct uart_port *port, struct serial_struct *ser)
{
if (port->type != PORT_UNKNOWN && ser->type != PORT_ARC)
return -EINVAL;
return 0;
}
/*
* Configure/autoconfigure the port.
*/
static void arc_serial_config_port(struct uart_port *port, int flags)
{
struct arc_uart_port *uart = to_arc_port(port);
if (flags & UART_CONFIG_TYPE)
uart->port.type = PORT_ARC;
}
#if defined(CONFIG_CONSOLE_POLL) || defined(CONFIG_SERIAL_ARC_CONSOLE)
static void arc_serial_poll_putchar(struct uart_port *port, unsigned char chr)
{
struct arc_uart_port *uart = to_arc_port(port);
while (!(UART_GET_STATUS(uart) & TXEMPTY))
cpu_relax();
UART_SET_DATA(uart, chr);
}
#endif
#ifdef CONFIG_CONSOLE_POLL
static int arc_serial_poll_getchar(struct uart_port *port)
{
struct arc_uart_port *uart = to_arc_port(port);
unsigned char chr;
while (!(UART_GET_STATUS(uart) & RXEMPTY))
cpu_relax();
chr = UART_GET_DATA(uart);
return chr;
}
#endif
static struct uart_ops arc_serial_pops = {
.tx_empty = arc_serial_tx_empty,
.set_mctrl = arc_serial_set_mctrl,
.get_mctrl = arc_serial_get_mctrl,
.stop_tx = arc_serial_stop_tx,
.start_tx = arc_serial_start_tx,
.stop_rx = arc_serial_stop_rx,
.enable_ms = arc_serial_enable_ms,
.break_ctl = arc_serial_break_ctl,
.startup = arc_serial_startup,
.shutdown = arc_serial_shutdown,
.set_termios = arc_serial_set_termios,
.type = arc_serial_type,
.release_port = arc_serial_release_port,
.request_port = arc_serial_request_port,
.config_port = arc_serial_config_port,
.verify_port = arc_serial_verify_port,
#ifdef CONFIG_CONSOLE_POLL
.poll_put_char = arc_serial_poll_putchar,
.poll_get_char = arc_serial_poll_getchar,
#endif
};
static int
arc_uart_init_one(struct platform_device *pdev, struct arc_uart_port *uart)
{
struct resource *res, *res2;
unsigned long *plat_data;
if (pdev->id < 0 || pdev->id >= CONFIG_SERIAL_ARC_NR_PORTS) {
dev_err(&pdev->dev, "Wrong uart platform device id.\n");
return -ENOENT;
}
plat_data = ((unsigned long *)(pdev->dev.platform_data));
uart->baud = plat_data[0];
res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
if (!res)
return -ENODEV;
res2 = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
if (!res2)
return -ENODEV;
uart->port.mapbase = res->start;
uart->port.membase = ioremap_nocache(res->start, resource_size(res));
if (!uart->port.membase)
/* No point of dev_err since UART itself is hosed here */
return -ENXIO;
uart->port.irq = res2->start;
uart->port.dev = &pdev->dev;
uart->port.iotype = UPIO_MEM;
uart->port.flags = UPF_BOOT_AUTOCONF;
uart->port.line = pdev->id;
uart->port.ops = &arc_serial_pops;
uart->port.uartclk = plat_data[1];
uart->port.fifosize = ARC_UART_TX_FIFO_SIZE;
/*
* uart_insert_char( ) uses it in decideding whether to ignore a
* char or not. Explicitly setting it here, removes the subtelty
*/
uart->port.ignore_status_mask = 0;
/* Real Hardware vs. emulated to work around a bug */
uart->is_emulated = !!plat_data[2];
return 0;
}
#ifdef CONFIG_SERIAL_ARC_CONSOLE
static int arc_serial_console_setup(struct console *co, char *options)
{
struct uart_port *port;
int baud = 115200;
int bits = 8;
int parity = 'n';
int flow = 'n';
if (co->index < 0 || co->index >= CONFIG_SERIAL_ARC_NR_PORTS)
return -ENODEV;
/*
* The uart port backing the console (e.g. ttyARC1) might not have been
* init yet. If so, defer the console setup to after the port.
*/
port = &arc_uart_ports[co->index].port;
if (!port->membase)
return -ENODEV;
if (options)
uart_parse_options(options, &baud, &parity, &bits, &flow);
/*
* Serial core will call port->ops->set_termios( )
* which will set the baud reg
*/
return uart_set_options(port, co, baud, parity, bits, flow);
}
static void arc_serial_console_putchar(struct uart_port *port, int ch)
{
arc_serial_poll_putchar(port, (unsigned char)ch);
}
/*
* Interrupts are disabled on entering
*/
static void arc_serial_console_write(struct console *co, const char *s,
unsigned int count)
{
struct uart_port *port = &arc_uart_ports[co->index].port;
unsigned long flags;
spin_lock_irqsave(&port->lock, flags);
uart_console_write(port, s, count, arc_serial_console_putchar);
spin_unlock_irqrestore(&port->lock, flags);
}
static struct console arc_console = {
.name = ARC_SERIAL_DEV_NAME,
.write = arc_serial_console_write,
.device = uart_console_device,
.setup = arc_serial_console_setup,
.flags = CON_PRINTBUFFER,
.index = -1,
.data = &arc_uart_driver
};
static __init void early_serial_write(struct console *con, const char *s,
unsigned int n)
{
struct uart_port *port = &arc_uart_ports[con->index].port;
unsigned int i;
for (i = 0; i < n; i++, s++) {
if (*s == '\n')
arc_serial_poll_putchar(port, '\r');
arc_serial_poll_putchar(port, *s);
}
}
static struct __initdata console arc_early_serial_console = {
.name = "early_ARCuart",
.write = early_serial_write,
.flags = CON_PRINTBUFFER | CON_BOOT,
.index = -1
};
static int arc_serial_probe_earlyprintk(struct platform_device *pdev)
{
arc_early_serial_console.index = pdev->id;
arc_uart_init_one(pdev, &arc_uart_ports[pdev->id]);
arc_serial_console_setup(&arc_early_serial_console, NULL);
register_console(&arc_early_serial_console);
return 0;
}
#else
static int arc_serial_probe_earlyprintk(struct platform_device *pdev)
{
return -ENODEV;
}
#endif /* CONFIG_SERIAL_ARC_CONSOLE */
static int arc_serial_probe(struct platform_device *pdev)
{
struct arc_uart_port *uart;
int rc;
if (is_early_platform_device(pdev))
return arc_serial_probe_earlyprintk(pdev);
uart = &arc_uart_ports[pdev->id];
rc = arc_uart_init_one(pdev, uart);
if (rc)
return rc;
return uart_add_one_port(&arc_uart_driver, &uart->port);
}
static int __devexit arc_serial_remove(struct platform_device *pdev)
{
/* This will never be called */
return 0;
}
static struct platform_driver arc_platform_driver = {
.probe = arc_serial_probe,
.remove = arc_serial_remove,
.driver = {
.name = DRIVER_NAME,
.owner = THIS_MODULE,
},
};
#ifdef CONFIG_SERIAL_ARC_CONSOLE
/*
* Register an early platform driver of "earlyprintk" class.
* ARCH platform code installs the driver and probes the early devices
* The installation could rely on user specifying earlyprintk=xyx in cmd line
* or it could be done independently, for all "earlyprintk" class drivers.
* [see arch/arc/plat-arcfpga/platform.c]
*/
early_platform_init("earlyprintk", &arc_platform_driver);
#endif /* CONFIG_SERIAL_ARC_CONSOLE */
static int __init arc_serial_init(void)
{
int ret;
ret = uart_register_driver(&arc_uart_driver);
if (ret)
return ret;
ret = platform_driver_register(&arc_platform_driver);
if (ret)
uart_unregister_driver(&arc_uart_driver);
return ret;
}
static void __exit arc_serial_exit(void)
{
platform_driver_unregister(&arc_platform_driver);
uart_unregister_driver(&arc_uart_driver);
}
module_init(arc_serial_init);
module_exit(arc_serial_exit);
MODULE_LICENSE("GPL");
MODULE_ALIAS("plat-arcfpga/uart");
MODULE_AUTHOR("Vineet Gupta");
MODULE_DESCRIPTION("ARC(Synopsys) On-Chip(fpga) serial driver");
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