/*
* mrst_max3110.c - spi uart protocol driver for Maxim 3110
*
* Copyright (c) 2008-2010, Intel Corporation.
*
* This program is free software; you can redistribute it and/or modify it
* under the terms and conditions of the GNU General Public License,
* version 2, as published by the Free Software Foundation.
*
* This program is distributed in the hope 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.,
* 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA.
*/
/*
* Note:
* 1. From Max3110 spec, the Rx FIFO has 8 words, while the Tx FIFO only has
* 1 word. If SPI master controller doesn't support sclk frequency change,
* then the char need be sent out one by one with some delay
*
* 2. Currently only RX available interrrupt is used, no need for waiting TXE
* interrupt for a low speed UART device
*/
#include <linux/module.h>
#include <linux/ioport.h>
#include <linux/irq.h>
#include <linux/init.h>
#include <linux/console.h>
#include <linux/tty.h>
#include <linux/tty_flip.h>
#include <linux/serial_core.h>
#include <linux/serial_reg.h>
#include <linux/kthread.h>
#include <linux/spi/spi.h>
#include "mrst_max3110.h"
#define PR_FMT "mrst_max3110: "
#define UART_TX_NEEDED 1
#define CON_TX_NEEDED 2
#define BIT_IRQ_PENDING 3
struct uart_max3110 {
struct uart_port port;
struct spi_device *spi;
char name[SPI_NAME_SIZE];
wait_queue_head_t wq;
struct task_struct *main_thread;
struct task_struct *read_thread;
struct mutex thread_mutex;;
u32 baud;
u16 cur_conf;
u8 clock;
u8 parity, word_7bits;
u16 irq;
unsigned long uart_flags;
/* console related */
struct circ_buf con_xmit;
};
/* global data structure, may need be removed */
static struct uart_max3110 *pmax;
static void receive_chars(struct uart_max3110 *max,
unsigned char *str, int len);
static int max3110_read_multi(struct uart_max3110 *max, u8 *buf);
static void max3110_con_receive(struct uart_max3110 *max);
static int max3110_write_then_read(struct uart_max3110 *max,
const void *txbuf, void *rxbuf, unsigned len, int always_fast)
{
struct spi_device *spi = max->spi;
struct spi_message message;
struct spi_transfer x;
int ret;
spi_message_init(&message);
memset(&x, 0, sizeof x);
x.len = len;
x.tx_buf = txbuf;
x.rx_buf = rxbuf;
spi_message_add_tail(&x, &message);
if (always_fast)
x.speed_hz = spi->max_speed_hz;
else if (max->baud)
x.speed_hz = max->baud;
/* Do the i/o */
ret = spi_sync(spi, &message);
return ret;
}
/* Write a 16b word to the device */
static int max3110_out(struct uart_max3110 *max, const u16 out)
{
void *buf;
u16 *obuf, *ibuf;
u8 ch;
int ret;
buf = kzalloc(8, GFP_KERNEL | GFP_DMA);
if (!buf)
return -ENOMEM;
obuf = buf;
ibuf = buf + 4;
*obuf = out;
ret = max3110_write_then_read(max, obuf, ibuf, 2, 1);
if (ret) {
pr_warning(PR_FMT "%s(): get err msg %d when sending 0x%x\n",
__func__, ret, out);
goto exit;
}
/* If some valid data is read back */
if (*ibuf & MAX3110_READ_DATA_AVAILABLE) {
ch = *ibuf & 0xff;
receive_chars(max, &ch, 1);
}
exit:
kfree(buf);
return ret;
}
/*
* This is usually used to read data from SPIC RX FIFO, which doesn't
* need any delay like flushing character out.
*
* Return how many valide bytes are read back
*/
static int max3110_read_multi(struct uart_max3110 *max, u8 *rxbuf)
{
void *buf;
u16 *obuf, *ibuf;
u8 *pbuf, valid_str[M3110_RX_FIFO_DEPTH];
int i, j, blen;
blen = M3110_RX_FIFO_DEPTH * sizeof(u16);
buf = kzalloc(blen * 2, GFP_KERNEL | GFP_DMA);
if (!buf) {
pr_warning(PR_FMT "%s(): fail to alloc dma buffer\n", __func__);
return 0;
}
/* tx/rx always have the same length */
obuf = buf;
ibuf = buf + blen;
if (max3110_write_then_read(max, obuf, ibuf, blen, 1)) {
kfree(buf);
return 0;
}
/* If caller doesn't provide a buffer, then handle received char */
pbuf = rxbuf ? rxbuf : valid_str;
for (i = 0, j = 0; i < M3110_RX_FIFO_DEPTH; i++) {
if (ibuf[i] & MAX3110_READ_DATA_AVAILABLE)
pbuf[j++] = ibuf[i] & 0xff;
}
if (j && (pbuf == valid_str))
receive_chars(max, valid_str, j);
kfree(buf);
return j;
}
static void serial_m3110_con_putchar(struct uart_port *port, int ch)
{
struct uart_max3110 *max =
container_of(port, struct uart_max3110, port);
struct circ_buf *xmit = &max->con_xmit;
if (uart_circ_chars_free(xmit)) {
xmit->buf[xmit->head] = (char)ch;
xmit->head = (xmit->head + 1) & (PAGE_SIZE - 1);
}
}
/*
* Print a string to the serial port trying not to disturb
* any possible real use of the port...
*
* The console_lock must be held when we get here.
*/
static void serial_m3110_con_write(struct console *co,
const char *s, unsigned int count)
{
if (!pmax)
return;
uart_console_write(&pmax->port, s, count, serial_m3110_con_putchar);
if (!test_and_set_bit(CON_TX_NEEDED, &pmax->uart_flags))
wake_up_process(pmax->main_thread);
}
static int __init
serial_m3110_con_setup(struct console *co, char *options)
{
struct uart_max3110 *max = pmax;
int baud = 115200;
int bits = 8;
int parity = 'n';
int flow = 'n';
pr_info(PR_FMT "setting up console\n");
if (co->index == -1)
co->index = 0;
if (!max) {
pr_err(PR_FMT "pmax is NULL, return");
return -ENODEV;
}
if (options)
uart_parse_options(options, &baud, &parity, &bits, &flow);
return uart_set_options(&max->port, co, baud, parity, bits, flow);
}
static struct tty_driver *serial_m3110_con_device(struct console *co,
int *index)
{
struct uart_driver *p = co->data;
*index = co->index;
return p->tty_driver;
}
static struct uart_driver serial_m3110_reg;
static struct console serial_m3110_console = {
.name = "ttyS",
.write = serial_m3110_con_write,
.device = serial_m3110_con_device,
.setup = serial_m3110_con_setup,
.flags = CON_PRINTBUFFER,
.index = -1,
.data = &serial_m3110_reg,
};
static unsigned int serial_m3110_tx_empty(struct uart_port *port)
{
return 1;
}
static void serial_m3110_stop_tx(struct uart_port *port)
{
return;
}
/* stop_rx will be called in spin_lock env */
static void serial_m3110_stop_rx(struct uart_port *port)
{
return;
}
#define WORDS_PER_XFER 128
static void send_circ_buf(struct uart_max3110 *max,
struct circ_buf *xmit)
{
void *buf;
u16 *obuf, *ibuf;
u8 valid_str[WORDS_PER_XFER];
int i, j, len, blen, dma_size, left, ret = 0;
dma_size = WORDS_PER_XFER * sizeof(u16) * 2;
buf = kzalloc(dma_size, GFP_KERNEL | GFP_DMA);
if (!buf)
return;
obuf = buf;
ibuf = buf + dma_size/2;
while (!uart_circ_empty(xmit)) {
left = uart_circ_chars_pending(xmit);
while (left) {
len = min(left, WORDS_PER_XFER);
blen = len * sizeof(u16);
memset(ibuf, 0, blen);
for (i = 0; i < len; i++) {
obuf[i] = (u8)xmit->buf[xmit->tail] | WD_TAG;
xmit->tail = (xmit->tail + 1) &
(UART_XMIT_SIZE - 1);
}
/* Fail to send msg to console is not very critical */
ret = max3110_write_then_read(max, obuf, ibuf, blen, 0);
if (ret)
pr_warning(PR_FMT "%s(): get err msg %d\n",
__func__, ret);
for (i = 0, j = 0; i < len; i++) {
if (ibuf[i] & MAX3110_READ_DATA_AVAILABLE)
valid_str[j++] = ibuf[i] & 0xff;
}
if (j)
receive_chars(max, valid_str, j);
max->port.icount.tx += len;
left -= len;
}
}
kfree(buf);
}
static void transmit_char(struct uart_max3110 *max)
{
struct uart_port *port = &max->port;
struct circ_buf *xmit = &port->state->xmit;
if (uart_circ_empty(xmit) || uart_tx_stopped(port))
return;
send_circ_buf(max, xmit);
if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
uart_write_wakeup(port);
if (uart_circ_empty(xmit))
serial_m3110_stop_tx(port);
}
/*
* This will be called by uart_write() and tty_write, can't
* go to sleep
*/
static void serial_m3110_start_tx(struct uart_port *port)
{
struct uart_max3110 *max =
container_of(port, struct uart_max3110, port);
if (!test_and_set_bit(UART_TX_NEEDED, &max->uart_flags))
wake_up_process(max->main_thread);
}
static void receive_chars(struct uart_max3110 *max, unsigned char *str, int len)
{
struct uart_port *port = &max->port;
struct tty_struct *tty;
int usable;
/* If uart is not opened, just return */
if (!port->state)
return;
tty = port->state->port.tty;
if (!tty)
return;
while (len) {
usable = tty_buffer_request_room(tty, len);
if (usable) {
tty_insert_flip_string(tty, str, usable);
str += usable;
port->icount.rx += usable;
}
len -= usable;
}
tty_flip_buffer_push(tty);
}
/*
* This routine will be used in read_thread or RX IRQ handling,
* it will first do one round buffer read(8 words), if there is some
* valid RX data, will try to read 5 more rounds till all data
* is read out.
*
* Use stack space as data buffer to save some system load, and chose
* 504 Btyes as a threadhold to do a bulk push to upper tty layer when
* receiving bulk data, a much bigger buffer may cause stack overflow
*/
static void max3110_con_receive(struct uart_max3110 *max)
{
int loop = 1, num, total = 0;
u8 recv_buf[512], *pbuf;
pbuf = recv_buf;
do {
num = max3110_read_multi(max, pbuf);
if (num) {
loop = 5;
pbuf += num;
total += num;
if (total >= 504) {
receive_chars(max, recv_buf, total);
pbuf = recv_buf;
total = 0;
}
}
} while (--loop);
if (total)
receive_chars(max, recv_buf, total);
}
static int max3110_main_thread(void *_max)
{
struct uart_max3110 *max = _max;
wait_queue_head_t *wq = &max->wq;
int ret = 0;
struct circ_buf *xmit = &max->con_xmit;
init_waitqueue_head(wq);
pr_info(PR_FMT "start main thread\n");
do {
wait_event_interruptible(*wq, max->uart_flags || kthread_should_stop());
mutex_lock(&max->thread_mutex);
if (test_and_clear_bit(BIT_IRQ_PENDING, &max->uart_flags))
max3110_con_receive(max);
/* first handle console output */
if (test_and_clear_bit(CON_TX_NEEDED, &max->uart_flags))
send_circ_buf(max, xmit);
/* handle uart output */
if (test_and_clear_bit(UART_TX_NEEDED, &max->uart_flags))
transmit_char(max);
mutex_unlock(&max->thread_mutex);
} while (!kthread_should_stop());
return ret;
}
static irqreturn_t serial_m3110_irq(int irq, void *dev_id)
{
struct uart_max3110 *max = dev_id;
/* max3110's irq is a falling edge, not level triggered,
* so no need to disable the irq */
if (!test_and_set_bit(BIT_IRQ_PENDING, &max->uart_flags))
wake_up_process(max->main_thread);
return IRQ_HANDLED;
}
/* if don't use RX IRQ, then need a thread to polling read */
static int max3110_read_thread(void *_max)
{
struct uart_max3110 *max = _max;
pr_info(PR_FMT "start read thread\n");
do {
/*
* If can't acquire the mutex, it means the main thread
* is running which will also perform the rx job
*/
if (mutex_trylock(&max->thread_mutex)) {
max3110_con_receive(max);
mutex_unlock(&max->thread_mutex);
}
set_current_state(TASK_INTERRUPTIBLE);
schedule_timeout(HZ / 20);
} while (!kthread_should_stop());
return 0;
}
static int serial_m3110_startup(struct uart_port *port)
{
struct uart_max3110 *max =
container_of(port, struct uart_max3110, port);
u16 config = 0;
int ret = 0;
if (port->line != 0) {
pr_err(PR_FMT "uart port startup failed\n");
return -1;
}
/* Disable all IRQ and config it to 115200, 8n1 */
config = WC_TAG | WC_FIFO_ENABLE
| WC_1_STOPBITS
| WC_8BIT_WORD
| WC_BAUD_DR2;
/* as we use thread to handle tx/rx, need set low latency */
port->state->port.tty->low_latency = 1;
if (max->irq) {
max->read_thread = NULL;
ret = request_irq(max->irq, serial_m3110_irq,
IRQ_TYPE_EDGE_FALLING, "max3110", max);
if (ret) {
max->irq = 0;
pr_err(PR_FMT "unable to allocate IRQ, polling\n");
} else {
/* Enable RX IRQ only */
config |= WC_RXA_IRQ_ENABLE;
}
}
if (max->irq == 0) {
/* If IRQ is disabled, start a read thread for input data */
max->read_thread =
kthread_run(max3110_read_thread, max, "max3110_read");
if (IS_ERR(max->read_thread)) {
ret = PTR_ERR(max->read_thread);
max->read_thread = NULL;
pr_err(PR_FMT "Can't create read thread!\n");
return ret;
}
}
ret = max3110_out(max, config);
if (ret) {
if (max->irq)
free_irq(max->irq, max);
if (max->read_thread)
kthread_stop(max->read_thread);
max->read_thread = NULL;
return ret;
}
max->cur_conf = config;
return 0;
}
static void serial_m3110_shutdown(struct uart_port *port)
{
struct uart_max3110 *max =
container_of(port, struct uart_max3110, port);
u16 config;
if (max->read_thread) {
kthread_stop(max->read_thread);
max->read_thread = NULL;
}
if (max->irq)
free_irq(max->irq, max);
/* Disable interrupts from this port */
config = WC_TAG | WC_SW_SHDI;
max3110_out(max, config);
}
static void serial_m3110_release_port(struct uart_port *port)
{
}
static int serial_m3110_request_port(struct uart_port *port)
{
return 0;
}
static void serial_m3110_config_port(struct uart_port *port, int flags)
{
port->type = PORT_MAX3100;
}
static int
serial_m3110_verify_port(struct uart_port *port, struct serial_struct *ser)
{
/* we don't want the core code to modify any port params */
return -EINVAL;
}
static const char *serial_m3110_type(struct uart_port *port)
{
struct uart_max3110 *max =
container_of(port, struct uart_max3110, port);
return max->name;
}
static void
serial_m3110_set_termios(struct uart_port *port, struct ktermios *termios,
struct ktermios *old)
{
struct uart_max3110 *max =
container_of(port, struct uart_max3110, port);
unsigned char cval;
unsigned int baud, parity = 0;
int clk_div = -1;
u16 new_conf = max->cur_conf;
switch (termios->c_cflag & CSIZE) {
case CS7:
cval = UART_LCR_WLEN7;
new_conf |= WC_7BIT_WORD;
break;
default:
/* We only support CS7 & CS8 */
termios->c_cflag &= ~CSIZE;
termios->c_cflag |= CS8;
case CS8:
cval = UART_LCR_WLEN8;
new_conf |= WC_8BIT_WORD;
break;
}
baud = uart_get_baud_rate(port, termios, old, 0, 230400);
/* First calc the div for 1.8MHZ clock case */
switch (baud) {
case 300:
clk_div = WC_BAUD_DR384;
break;
case 600:
clk_div = WC_BAUD_DR192;
break;
case 1200:
clk_div = WC_BAUD_DR96;
break;
case 2400:
clk_div = WC_BAUD_DR48;
break;
case 4800:
clk_div = WC_BAUD_DR24;
break;
case 9600:
clk_div = WC_BAUD_DR12;
break;
case 19200:
clk_div = WC_BAUD_DR6;
break;
case 38400:
clk_div = WC_BAUD_DR3;
break;
case 57600:
clk_div = WC_BAUD_DR2;
break;
case 115200:
clk_div = WC_BAUD_DR1;
break;
case 230400:
if (max->clock & MAX3110_HIGH_CLK)
break;
default:
/* Pick the previous baud rate */
baud = max->baud;
clk_div = max->cur_conf & WC_BAUD_DIV_MASK;
tty_termios_encode_baud_rate(termios, baud, baud);
}
if (max->clock & MAX3110_HIGH_CLK) {
clk_div += 1;
/* High clk version max3110 doesn't support B300 */
if (baud == 300) {
baud = 600;
clk_div = WC_BAUD_DR384;
}
if (baud == 230400)
clk_div = WC_BAUD_DR1;
tty_termios_encode_baud_rate(termios, baud, baud);
}
new_conf = (new_conf & ~WC_BAUD_DIV_MASK) | clk_div;
if (unlikely(termios->c_cflag & CMSPAR))
termios->c_cflag &= ~CMSPAR;
if (termios->c_cflag & CSTOPB)
new_conf |= WC_2_STOPBITS;
else
new_conf &= ~WC_2_STOPBITS;
if (termios->c_cflag & PARENB) {
new_conf |= WC_PARITY_ENABLE;
parity |= UART_LCR_PARITY;
} else
new_conf &= ~WC_PARITY_ENABLE;
if (!(termios->c_cflag & PARODD))
parity |= UART_LCR_EPAR;
max->parity = parity;
uart_update_timeout(port, termios->c_cflag, baud);
new_conf |= WC_TAG;
if (new_conf != max->cur_conf) {
if (!max3110_out(max, new_conf)) {
max->cur_conf = new_conf;
max->baud = baud;
}
}
}
/* Don't handle hw handshaking */
static unsigned int serial_m3110_get_mctrl(struct uart_port *port)
{
return TIOCM_DSR | TIOCM_CAR | TIOCM_DSR;
}
static void serial_m3110_set_mctrl(struct uart_port *port, unsigned int mctrl)
{
}
static void serial_m3110_break_ctl(struct uart_port *port, int break_state)
{
}
static void serial_m3110_pm(struct uart_port *port, unsigned int state,
unsigned int oldstate)
{
}
static void serial_m3110_enable_ms(struct uart_port *port)
{
}
struct uart_ops serial_m3110_ops = {
.tx_empty = serial_m3110_tx_empty,
.set_mctrl = serial_m3110_set_mctrl,
.get_mctrl = serial_m3110_get_mctrl,
.stop_tx = serial_m3110_stop_tx,
.start_tx = serial_m3110_start_tx,
.stop_rx = serial_m3110_stop_rx,
.enable_ms = serial_m3110_enable_ms,
.break_ctl = serial_m3110_break_ctl,
.startup = serial_m3110_startup,
.shutdown = serial_m3110_shutdown,
.set_termios = serial_m3110_set_termios,
.pm = serial_m3110_pm,
.type = serial_m3110_type,
.release_port = serial_m3110_release_port,
.request_port = serial_m3110_request_port,
.config_port = serial_m3110_config_port,
.verify_port = serial_m3110_verify_port,
};
static struct uart_driver serial_m3110_reg = {
.owner = THIS_MODULE,
.driver_name = "MRST serial",
.dev_name = "ttyS",
.major = TTY_MAJOR,
.minor = 64,
.nr = 1,
.cons = &serial_m3110_console,
};
#ifdef CONFIG_PM
static int serial_m3110_suspend(struct spi_device *spi, pm_message_t state)
{
struct uart_max3110 *max = spi_get_drvdata(spi);
disable_irq(max->irq);
uart_suspend_port(&serial_m3110_reg, &max->port);
max3110_out(max, max->cur_conf | WC_SW_SHDI);
return 0;
}
static int serial_m3110_resume(struct spi_device *spi)
{
struct uart_max3110 *max = spi_get_drvdata(spi);
max3110_out(max, max->cur_conf);
uart_resume_port(&serial_m3110_reg, &max->port);
enable_irq(max->irq);
return 0;
}
#else
#define serial_m3110_suspend NULL
#define serial_m3110_resume NULL
#endif
static int __devinit serial_m3110_probe(struct spi_device *spi)
{
struct uart_max3110 *max;
void *buffer;
u16 res;
int ret = 0;
max = kzalloc(sizeof(*max), GFP_KERNEL);
if (!max)
return -ENOMEM;
/* Set spi info */
spi->bits_per_word = 16;
max->clock = MAX3110_HIGH_CLK;
spi_setup(spi);
max->port.type = PORT_MAX3100;
max->port.fifosize = 2; /* Only have 16b buffer */
max->port.ops = &serial_m3110_ops;
max->port.line = 0;
max->port.dev = &spi->dev;
max->port.uartclk = 115200;
max->spi = spi;
strcpy(max->name, spi->modalias);
max->irq = (u16)spi->irq;
mutex_init(&max->thread_mutex);
max->word_7bits = 0;
max->parity = 0;
max->baud = 0;
max->cur_conf = 0;
max->uart_flags = 0;
/* Check if reading configuration register returns something sane */
res = RC_TAG;
ret = max3110_write_then_read(max, (u8 *)&res, (u8 *)&res, 2, 0);
if (ret < 0 || res == 0 || res == 0xffff) {
printk(KERN_ERR "MAX3111 deemed not present (conf reg %04x)",
res);
ret = -ENODEV;
goto err_get_page;
}
buffer = (void *)__get_free_page(GFP_KERNEL);
if (!buffer) {
ret = -ENOMEM;
goto err_get_page;
}
max->con_xmit.buf = buffer;
max->con_xmit.head = 0;
max->con_xmit.tail = 0;
max->main_thread = kthread_run(max3110_main_thread,
max, "max3110_main");
if (IS_ERR(max->main_thread)) {
ret = PTR_ERR(max->main_thread);
goto err_kthread;
}
spi_set_drvdata(spi, max);
pmax = max;
/* Give membase a psudo value to pass serial_core's check */
max->port.membase = (void *)0xff110000;
uart_add_one_port(&serial_m3110_reg, &max->port);
return 0;
err_kthread:
free_page((unsigned long)buffer);
err_get_page:
kfree(max);
return ret;
}
static int __devexit serial_m3110_remove(struct spi_device *dev)
{
struct uart_max3110 *max = spi_get_drvdata(dev);
if (!max)
return 0;
uart_remove_one_port(&serial_m3110_reg, &max->port);
free_page((unsigned long)max->con_xmit.buf);
if (max->main_thread)
kthread_stop(max->main_thread);
kfree(max);
return 0;
}
static struct spi_driver uart_max3110_driver = {
.driver = {
.name = "spi_max3111",
.bus = &spi_bus_type,
.owner = THIS_MODULE,
},
.probe = serial_m3110_probe,
.remove = __devexit_p(serial_m3110_remove),
.suspend = serial_m3110_suspend,
.resume = serial_m3110_resume,
};
static int __init serial_m3110_init(void)
{
int ret = 0;
ret = uart_register_driver(&serial_m3110_reg);
if (ret)
return ret;
ret = spi_register_driver(&uart_max3110_driver);
if (ret)
uart_unregister_driver(&serial_m3110_reg);
return ret;
}
static void __exit serial_m3110_exit(void)
{
spi_unregister_driver(&uart_max3110_driver);
uart_unregister_driver(&serial_m3110_reg);
}
module_init(serial_m3110_init);
module_exit(serial_m3110_exit);
MODULE_LICENSE("GPL v2");
MODULE_ALIAS("max3110-uart");