From 225109957a74c571c49e860fcc4e81fa6df1079d Mon Sep 17 00:00:00 2001 From: Feng Tang Date: Wed, 16 Jun 2010 14:46:09 +0100 Subject: mrst_max3110: add UART driver for Max3110 on Moorestown This driver enable the max3110 device, it can be used as a system console. the IRQ needs be enabled if user want a better performance. MRST max3110 works in 3.684MHz clock, which supports 230400 as its maximum rate. Signed-off-by: Feng Tang Signed-off-by: Alan Cox Signed-off-by: Greg Kroah-Hartman --- drivers/serial/mrst_max3110.c | 844 ++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 844 insertions(+) create mode 100644 drivers/serial/mrst_max3110.c (limited to 'drivers/serial/mrst_max3110.c') diff --git a/drivers/serial/mrst_max3110.c b/drivers/serial/mrst_max3110.c new file mode 100644 index 000000000000..273e7cbe74cd --- /dev/null +++ b/drivers/serial/mrst_max3110.c @@ -0,0 +1,844 @@ +/* + * max3110.c - spi uart protocol driver for Maxim 3110 on Moorestown + * + * Copyright (C) Intel 2008 Feng Tang + * + * 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 availabe interrrupt is used, no need for waiting TXE + * interrupt for a low speed UART device + */ + +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#include +#include +#include +#include +#include + +#include "mrst_max3110.h" + +#define PR_FMT "mrst_max3110: " + +struct uart_max3110 { + struct uart_port port; + struct spi_device *spi; + char *name; + + wait_queue_head_t wq; + struct task_struct *main_thread; + struct task_struct *read_thread; + int mthread_up; + spinlock_t lock; + + u32 baud; + u16 cur_conf; + u8 clock; + u8 parity, word_7bits; + + atomic_t uart_tx_need; + + /* console related */ + struct circ_buf con_xmit; + atomic_t con_tx_need; + + /* irq related */ + u16 irq; + atomic_t irq_pending; +}; + +/* global data structure, may need be removed */ +struct uart_max3110 *pmax; +static inline void receive_char(struct uart_max3110 *max, u8 ch); +static void receive_chars(struct uart_max3110 *max, + unsigned char *str, int len); +static int max3110_read_multi(struct uart_max3110 *max, int len, u8 *buf); +static void max3110_console_receive(struct uart_max3110 *max); + +int max3110_write_then_read(struct uart_max3110 *max, + const u8 *txbuf, u8 *rxbuf, unsigned len, int always_fast) +{ + struct spi_device *spi = max->spi; + struct spi_message message; + struct spi_transfer x; + int ret; + + if (!txbuf || !rxbuf) + return -EINVAL; + + 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 = 3125000; + else if (max->baud) + x.speed_hz = max->baud; + + /* Do the i/o */ + ret = spi_sync(spi, &message); + return ret; +} + +/* Write a u16 to the device, and return one u16 read back */ +int max3110_out(struct uart_max3110 *max, const u16 out) +{ + u16 tmp; + int ret; + + ret = max3110_write_then_read(max, (u8 *)&out, (u8 *)&tmp, 2, 1); + if (ret) + return ret; + + /* If some valid data is read back */ + if (tmp & MAX3110_READ_DATA_AVAILABLE) + receive_char(max, (tmp & 0xff)); + + return ret; +} + +#define MAX_READ_LEN 20 +/* + * This is usually used to read data from SPIC RX FIFO, which doesn't + * need any delay like flushing character out. It returns how many + * valide bytes are read back + */ +static int max3110_read_multi(struct uart_max3110 *max, int len, u8 *buf) +{ + u16 out[MAX_READ_LEN], in[MAX_READ_LEN]; + u8 *pbuf, valid_str[MAX_READ_LEN]; + int i, j, bytelen; + + if (len > MAX_READ_LEN) { + pr_err(PR_FMT "read len %d is too large\n", len); + return 0; + } + + bytelen = len * 2; + memset(out, 0, bytelen); + memset(in, 0, bytelen); + + if (max3110_write_then_read(max, (u8 *)out, (u8 *)in, bytelen, 1)) + return 0; + + /* If caller don't provide a buffer, then handle received char */ + pbuf = buf ? buf : valid_str; + + for (i = 0, j = 0; i < len; i++) { + if (in[i] & MAX3110_READ_DATA_AVAILABLE) + pbuf[j++] = (u8)(in[i] & 0xff); + } + + if (j && (pbuf == valid_str)) + receive_chars(max, valid_str, j); + + 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); + } + + if (!atomic_read(&max->con_tx_need)) { + atomic_set(&max->con_tx_need, 1); + wake_up_process(max->main_thread); + } +} + +/* + * 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); +} + +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 (!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, +}; + +#define MRST_CONSOLE (&serial_m3110_console) + +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 inline void send_circ_buf(struct uart_max3110 *max, + struct circ_buf *xmit) +{ + int len, left = 0; + u16 obuf[WORDS_PER_XFER], ibuf[WORDS_PER_XFER]; + u8 valid_str[WORDS_PER_XFER]; + int i, j; + + while (!uart_circ_empty(xmit)) { + left = uart_circ_chars_pending(xmit); + while (left) { + len = (left >= WORDS_PER_XFER) ? WORDS_PER_XFER : left; + + memset(obuf, 0, len * 2); + memset(ibuf, 0, len * 2); + for (i = 0; i < len; i++) { + obuf[i] = (u8)xmit->buf[xmit->tail] | WD_TAG; + xmit->tail = (xmit->tail + 1) & + (UART_XMIT_SIZE - 1); + } + max3110_write_then_read(max, (u8 *)obuf, + (u8 *)ibuf, len * 2, 0); + + for (i = 0, j = 0; i < len; i++) { + if (ibuf[i] & MAX3110_READ_DATA_AVAILABLE) + valid_str[j++] = (u8)(ibuf[i] & 0xff); + } + + if (j) + receive_chars(max, valid_str, j); + + max->port.icount.tx += len; + left -= len; + } + } +} + +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 (!atomic_read(&max->uart_tx_need)) { + atomic_set(&max->uart_tx_need, 1); + 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; /* receive some char before the tty is opened */ + + while (len) { + usable = tty_buffer_request_room(tty, len); + if (usable) { + tty_insert_flip_string(tty, str, usable); + str += usable; + port->icount.rx += usable; + tty_flip_buffer_push(tty); + } + len -= usable; + } +} + +static inline void receive_char(struct uart_max3110 *max, u8 ch) +{ + receive_chars(max, &ch, 1); +} + +static void max3110_console_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, 8, pbuf); + + if (num) { + loop = 10; + pbuf += num; + total += num; + + if (total >= 500) { + 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, (atomic_read(&max->irq_pending) || + atomic_read(&max->con_tx_need) || + atomic_read(&max->uart_tx_need)) || + kthread_should_stop()); + max->mthread_up = 1; + +#ifdef CONFIG_MRST_MAX3110_IRQ + if (atomic_read(&max->irq_pending)) { + max3110_console_receive(max); + atomic_set(&max->irq_pending, 0); + } +#endif + + /* first handle console output */ + if (atomic_read(&max->con_tx_need)) { + send_circ_buf(max, xmit); + atomic_set(&max->con_tx_need, 0); + } + + /* handle uart output */ + if (atomic_read(&max->uart_tx_need)) { + transmit_char(max); + atomic_set(&max->uart_tx_need, 0); + } + max->mthread_up = 0; + } while (!kthread_should_stop()); + + return ret; +} + +#ifdef CONFIG_MRST_MAX3110_IRQ +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 (!atomic_read(&max->irq_pending)) { + atomic_inc(&max->irq_pending); + wake_up_process(max->main_thread); + } + return IRQ_HANDLED; +} +#else +/* 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 (!max->mthread_up) + max3110_console_receive(max); + + set_current_state(TASK_INTERRUPTIBLE); + schedule_timeout(HZ / 20); + } while (!kthread_should_stop()); + + return 0; +} +#endif + +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"); + + /* firstly disable all IRQ and config it to 115200, 8n1 */ + config = WC_TAG | WC_FIFO_ENABLE + | WC_1_STOPBITS + | WC_8BIT_WORD + | WC_BAUD_DR2; + ret = max3110_out(max, config); + + /* as we use thread to handle tx/rx, need set low latency */ + port->state->port.tty->low_latency = 1; + +#ifdef CONFIG_MRST_MAX3110_IRQ + ret = request_irq(max->irq, serial_m3110_irq, + IRQ_TYPE_EDGE_FALLING, "max3110", max); + if (ret) + return ret; + + /* enable RX IRQ only */ + config |= WC_RXA_IRQ_ENABLE; + max3110_out(max, config); +#else + /* if IRQ is disabled, start a read thread for input data */ + max->read_thread = + kthread_run(max3110_read_thread, max, "max3110_read"); +#endif + + 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; + } + +#ifdef CONFIG_MRST_MAX3110_IRQ + free_irq(max->irq, max); +#endif + + /* 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) +{ + /* give it fake type */ + port->type = PORT_PXA; +} + +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: + 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; + 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 (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) { + 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, /* must have */ + .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 = MRST_CONSOLE, +}; + +static int serial_m3110_suspend(struct spi_device *spi, pm_message_t state) +{ + return 0; +} + +static int serial_m3110_resume(struct spi_device *spi) +{ + return 0; +} + +static struct dw_spi_chip spi0_uart = { + .poll_mode = 1, + .enable_dma = 0, + .type = SPI_FRF_SPI, +}; + +static int serial_m3110_probe(struct spi_device *spi) +{ + struct uart_max3110 *max; + int ret; + unsigned char *buffer; + + max = kzalloc(sizeof(*max), GFP_KERNEL); + if (!max) + return -ENOMEM; + + /* set spi info */ + spi->mode = SPI_MODE_0; + spi->bits_per_word = 16; + max->clock = MAX3110_HIGH_CLK; + spi->controller_data = &spi0_uart; + + spi_setup(spi); + + max->port.type = PORT_PXA; /* need apply for a max3110 type */ + 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; + max->name = spi->modalias; /* use spi name as the name */ + max->irq = (u16)spi->irq; + + spin_lock_init(&max->lock); + + max->word_7bits = 0; + max->parity = 0; + max->baud = 0; + + max->cur_conf = 0; + atomic_set(&max->irq_pending, 0); + + buffer = (unsigned char *)__get_free_page(GFP_KERNEL); + if (!buffer) { + ret = -ENOMEM; + goto err_get_page; + } + max->con_xmit.buf = (unsigned char *)buffer; + max->con_xmit.head = 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; + } + + 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: + pmax = NULL; + kfree(max); + return ret; +} + +static int max3110_remove(struct spi_device *dev) +{ + struct uart_max3110 *max = pmax; + + if (!pmax) + return 0; + + pmax = NULL; + 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(max3110_remove), + .suspend = serial_m3110_suspend, + .resume = serial_m3110_resume, +}; + + +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; +} + +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"); +MODULE_ALIAS("max3110-uart"); -- cgit From 99dd3f6b7e2ef5179f67503a401a99141708687a Mon Sep 17 00:00:00 2001 From: "jianwei.yang" Date: Wed, 16 Jun 2010 14:46:49 +0100 Subject: max3110 sanity check a register MAX3111 is the SPI/UART IC installed on the MRST SPI Port Card as a serial debug goal, and the SPI Port Card will be frequently mounted and unmounted from the main board by developers depending whether debug serial is required or not. As the MAX3111 has no subvendor or product id registers available, the patch will try to access one register to decide if this IC is present or not. Signed-off-by: Alan Cox Signed-off-by: Greg Kroah-Hartman --- drivers/serial/mrst_max3110.c | 13 +++++++++++-- 1 file changed, 11 insertions(+), 2 deletions(-) (limited to 'drivers/serial/mrst_max3110.c') diff --git a/drivers/serial/mrst_max3110.c b/drivers/serial/mrst_max3110.c index 273e7cbe74cd..f9c01aeb6f80 100644 --- a/drivers/serial/mrst_max3110.c +++ b/drivers/serial/mrst_max3110.c @@ -721,7 +721,7 @@ static int serial_m3110_probe(struct spi_device *spi) struct uart_max3110 *max; int ret; unsigned char *buffer; - + u16 res; max = kzalloc(sizeof(*max), GFP_KERNEL); if (!max) return -ENOMEM; @@ -753,7 +753,16 @@ static int serial_m3110_probe(struct spi_device *spi) max->cur_conf = 0; atomic_set(&max->irq_pending, 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 = (unsigned char *)__get_free_page(GFP_KERNEL); if (!buffer) { ret = -ENOMEM; -- cgit From 68c16b4117cc746a91897d629b61e5f2af18c225 Mon Sep 17 00:00:00 2001 From: Arjan van de Ven Date: Thu, 17 Jun 2010 11:02:06 +0100 Subject: serial: replace open coded mutex with a real mutex in mrst_max3110.c The mrst_max3110.c driver uses an open coded, non atomic variable to create exclusion between two of its worker threads. More than that, while the main thread does a proper set-work-clear sequence, the other thread only does a test, with the result that no actual exclusion is happening. this patch replaces this open coded variable with a proper mutex in addition, the 'lock' spinlock is removed from the per adapter structure, the lock was only ever initialized but never used Signed-off-by: Arjan van de Ven Signed-off-by: Alan Cox Signed-off-by: Greg Kroah-Hartman --- drivers/serial/mrst_max3110.c | 15 ++++++++------- 1 file changed, 8 insertions(+), 7 deletions(-) (limited to 'drivers/serial/mrst_max3110.c') diff --git a/drivers/serial/mrst_max3110.c b/drivers/serial/mrst_max3110.c index f9c01aeb6f80..0341853e0c28 100644 --- a/drivers/serial/mrst_max3110.c +++ b/drivers/serial/mrst_max3110.c @@ -56,8 +56,7 @@ struct uart_max3110 { wait_queue_head_t wq; struct task_struct *main_thread; struct task_struct *read_thread; - int mthread_up; - spinlock_t lock; + struct mutex thread_mutex;; u32 baud; u16 cur_conf; @@ -397,7 +396,8 @@ static int max3110_main_thread(void *_max) atomic_read(&max->con_tx_need) || atomic_read(&max->uart_tx_need)) || kthread_should_stop()); - max->mthread_up = 1; + + mutex_lock(&max->thread_mutex); #ifdef CONFIG_MRST_MAX3110_IRQ if (atomic_read(&max->irq_pending)) { @@ -417,7 +417,7 @@ static int max3110_main_thread(void *_max) transmit_char(max); atomic_set(&max->uart_tx_need, 0); } - max->mthread_up = 0; + mutex_unlock(&max->thread_mutex); } while (!kthread_should_stop()); return ret; @@ -444,8 +444,9 @@ static int max3110_read_thread(void *_max) pr_info(PR_FMT "start read thread\n"); do { - if (!max->mthread_up) - max3110_console_receive(max); + mutex_lock(&max->thread_mutex); + max3110_console_receive(max); + mutex_unlock(&max->thread_mutex); set_current_state(TASK_INTERRUPTIBLE); schedule_timeout(HZ / 20); @@ -745,7 +746,7 @@ static int serial_m3110_probe(struct spi_device *spi) max->name = spi->modalias; /* use spi name as the name */ max->irq = (u16)spi->irq; - spin_lock_init(&max->lock); + mutex_init(&max->thread_mutex); max->word_7bits = 0; max->parity = 0; -- cgit From d6e679b474c096f1125087e789e7af8886de39d3 Mon Sep 17 00:00:00 2001 From: Arjan van de Ven Date: Thu, 17 Jun 2010 11:02:15 +0100 Subject: serial: fix wakup races in the mrst_max3110 driver The mrst_max3110 driver had a set of unsafe wakeup sequences along the following line: if (!atomic_read(&foo)) { atomic_set(&foo, 1); wake_up(worker_thread); } and the worker thread would do if (atomic_read(&foo)) { do_work(); atomic_set(&foo, 0); } which can result in various missed wakups due to test-then-set races, as well as due to clear-after-work instead of clear-before-work. This patch fixes these races by using the proper bit test-and-set operations, and by doing clear-before-work. Signed-off-by: Arjan van de Ven Signed-off-by: Alan Cox Signed-off-by: Greg Kroah-Hartman --- drivers/serial/mrst_max3110.c | 46 +++++++++++++++++-------------------------- 1 file changed, 18 insertions(+), 28 deletions(-) (limited to 'drivers/serial/mrst_max3110.c') diff --git a/drivers/serial/mrst_max3110.c b/drivers/serial/mrst_max3110.c index 0341853e0c28..f6ad1ecbff79 100644 --- a/drivers/serial/mrst_max3110.c +++ b/drivers/serial/mrst_max3110.c @@ -48,6 +48,10 @@ #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; @@ -63,15 +67,13 @@ struct uart_max3110 { u8 clock; u8 parity, word_7bits; - atomic_t uart_tx_need; + unsigned long uart_flags; /* console related */ struct circ_buf con_xmit; - atomic_t con_tx_need; /* irq related */ u16 irq; - atomic_t irq_pending; }; /* global data structure, may need be removed */ @@ -176,10 +178,9 @@ static void serial_m3110_con_putchar(struct uart_port *port, int ch) xmit->head = (xmit->head + 1) & (PAGE_SIZE - 1); } - if (!atomic_read(&max->con_tx_need)) { - atomic_set(&max->con_tx_need, 1); + + if (!test_and_set_bit(CON_TX_NEEDED, &max->uart_flags)) wake_up_process(max->main_thread); - } } /* @@ -318,10 +319,8 @@ static void serial_m3110_start_tx(struct uart_port *port) struct uart_max3110 *max = container_of(port, struct uart_max3110, port); - if (!atomic_read(&max->uart_tx_need)) { - atomic_set(&max->uart_tx_need, 1); + 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) @@ -392,32 +391,23 @@ static int max3110_main_thread(void *_max) pr_info(PR_FMT "start main thread\n"); do { - wait_event_interruptible(*wq, (atomic_read(&max->irq_pending) || - atomic_read(&max->con_tx_need) || - atomic_read(&max->uart_tx_need)) || - kthread_should_stop()); + wait_event_interruptible(*wq, max->uart_flags || kthread_should_stop()); mutex_lock(&max->thread_mutex); -#ifdef CONFIG_MRST_MAX3110_IRQ - if (atomic_read(&max->irq_pending)) { + if (test_and_clear_bit(BIT_IRQ_PENDING, &max->uart_flags)) max3110_console_receive(max); - atomic_set(&max->irq_pending, 0); - } -#endif /* first handle console output */ - if (atomic_read(&max->con_tx_need)) { + if (test_and_clear_bit(CON_TX_NEEDED, &max->uart_flags)) send_circ_buf(max, xmit); - atomic_set(&max->con_tx_need, 0); - } /* handle uart output */ - if (atomic_read(&max->uart_tx_need)) { + if (test_and_clear_bit(UART_TX_NEEDED, &max->uart_flags)) transmit_char(max); - atomic_set(&max->uart_tx_need, 0); - } + mutex_unlock(&max->thread_mutex); + } while (!kthread_should_stop()); return ret; @@ -430,10 +420,9 @@ static irqreturn_t serial_m3110_irq(int irq, void *dev_id) /* max3110's irq is a falling edge, not level triggered, * so no need to disable the irq */ - if (!atomic_read(&max->irq_pending)) { - atomic_inc(&max->irq_pending); + if (!test_and_set_bit(BIT_IRQ_PENDING, &max->uart_flags)) wake_up_process(max->main_thread); - } + return IRQ_HANDLED; } #else @@ -753,7 +742,8 @@ static int serial_m3110_probe(struct spi_device *spi) max->baud = 0; max->cur_conf = 0; - atomic_set(&max->irq_pending, 0); + max->uart_flags = 0; + /* Check if reading configuration register returns something sane */ res = RC_TAG; -- cgit