/* * st-asc.c: ST Asynchronous serial controller (ASC) driver * * Copyright (C) 2003-2013 STMicroelectronics (R&D) Limited * * 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. * */ #if defined(CONFIG_SERIAL_ST_ASC_CONSOLE) && defined(CONFIG_MAGIC_SYSRQ) #define SUPPORT_SYSRQ #endif #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #define DRIVER_NAME "st-asc" #define ASC_SERIAL_NAME "ttyAS" #define ASC_FIFO_SIZE 16 #define ASC_MAX_PORTS 8 struct asc_port { struct uart_port port; struct clk *clk; unsigned int hw_flow_control:1; unsigned int force_m1:1; }; static struct asc_port asc_ports[ASC_MAX_PORTS]; static struct uart_driver asc_uart_driver; /*---- UART Register definitions ------------------------------*/ /* Register offsets */ #define ASC_BAUDRATE 0x00 #define ASC_TXBUF 0x04 #define ASC_RXBUF 0x08 #define ASC_CTL 0x0C #define ASC_INTEN 0x10 #define ASC_STA 0x14 #define ASC_GUARDTIME 0x18 #define ASC_TIMEOUT 0x1C #define ASC_TXRESET 0x20 #define ASC_RXRESET 0x24 #define ASC_RETRIES 0x28 /* ASC_RXBUF */ #define ASC_RXBUF_PE 0x100 #define ASC_RXBUF_FE 0x200 /** * Some of status comes from higher bits of the character and some come from * the status register. Combining both of them in to single status using dummy * bits. */ #define ASC_RXBUF_DUMMY_RX 0x10000 #define ASC_RXBUF_DUMMY_BE 0x20000 #define ASC_RXBUF_DUMMY_OE 0x40000 /* ASC_CTL */ #define ASC_CTL_MODE_MSK 0x0007 #define ASC_CTL_MODE_8BIT 0x0001 #define ASC_CTL_MODE_7BIT_PAR 0x0003 #define ASC_CTL_MODE_9BIT 0x0004 #define ASC_CTL_MODE_8BIT_WKUP 0x0005 #define ASC_CTL_MODE_8BIT_PAR 0x0007 #define ASC_CTL_STOP_MSK 0x0018 #define ASC_CTL_STOP_HALFBIT 0x0000 #define ASC_CTL_STOP_1BIT 0x0008 #define ASC_CTL_STOP_1_HALFBIT 0x0010 #define ASC_CTL_STOP_2BIT 0x0018 #define ASC_CTL_PARITYODD 0x0020 #define ASC_CTL_LOOPBACK 0x0040 #define ASC_CTL_RUN 0x0080 #define ASC_CTL_RXENABLE 0x0100 #define ASC_CTL_SCENABLE 0x0200 #define ASC_CTL_FIFOENABLE 0x0400 #define ASC_CTL_CTSENABLE 0x0800 #define ASC_CTL_BAUDMODE 0x1000 /* ASC_GUARDTIME */ #define ASC_GUARDTIME_MSK 0x00FF /* ASC_INTEN */ #define ASC_INTEN_RBE 0x0001 #define ASC_INTEN_TE 0x0002 #define ASC_INTEN_THE 0x0004 #define ASC_INTEN_PE 0x0008 #define ASC_INTEN_FE 0x0010 #define ASC_INTEN_OE 0x0020 #define ASC_INTEN_TNE 0x0040 #define ASC_INTEN_TOI 0x0080 #define ASC_INTEN_RHF 0x0100 /* ASC_RETRIES */ #define ASC_RETRIES_MSK 0x00FF /* ASC_RXBUF */ #define ASC_RXBUF_MSK 0x03FF /* ASC_STA */ #define ASC_STA_RBF 0x0001 #define ASC_STA_TE 0x0002 #define ASC_STA_THE 0x0004 #define ASC_STA_PE 0x0008 #define ASC_STA_FE 0x0010 #define ASC_STA_OE 0x0020 #define ASC_STA_TNE 0x0040 #define ASC_STA_TOI 0x0080 #define ASC_STA_RHF 0x0100 #define ASC_STA_TF 0x0200 #define ASC_STA_NKD 0x0400 /* ASC_TIMEOUT */ #define ASC_TIMEOUT_MSK 0x00FF /* ASC_TXBUF */ #define ASC_TXBUF_MSK 0x01FF /*---- Inline function definitions ---------------------------*/ static inline struct asc_port *to_asc_port(struct uart_port *port) { return container_of(port, struct asc_port, port); } static inline u32 asc_in(struct uart_port *port, u32 offset) { #ifdef readl_relaxed return readl_relaxed(port->membase + offset); #else return readl(port->membase + offset); #endif } static inline void asc_out(struct uart_port *port, u32 offset, u32 value) { #ifdef writel_relaxed writel_relaxed(value, port->membase + offset); #else writel(value, port->membase + offset); #endif } /* * Some simple utility functions to enable and disable interrupts. * Note that these need to be called with interrupts disabled. */ static inline void asc_disable_tx_interrupts(struct uart_port *port) { u32 intenable = asc_in(port, ASC_INTEN) & ~ASC_INTEN_THE; asc_out(port, ASC_INTEN, intenable); (void)asc_in(port, ASC_INTEN); /* Defeat bus write posting */ } static inline void asc_enable_tx_interrupts(struct uart_port *port) { u32 intenable = asc_in(port, ASC_INTEN) | ASC_INTEN_THE; asc_out(port, ASC_INTEN, intenable); } static inline void asc_disable_rx_interrupts(struct uart_port *port) { u32 intenable = asc_in(port, ASC_INTEN) & ~ASC_INTEN_RBE; asc_out(port, ASC_INTEN, intenable); (void)asc_in(port, ASC_INTEN); /* Defeat bus write posting */ } static inline void asc_enable_rx_interrupts(struct uart_port *port) { u32 intenable = asc_in(port, ASC_INTEN) | ASC_INTEN_RBE; asc_out(port, ASC_INTEN, intenable); } static inline u32 asc_txfifo_is_empty(struct uart_port *port) { return asc_in(port, ASC_STA) & ASC_STA_TE; } static inline u32 asc_txfifo_is_half_empty(struct uart_port *port) { return asc_in(port, ASC_STA) & ASC_STA_THE; } static inline const char *asc_port_name(struct uart_port *port) { return to_platform_device(port->dev)->name; } /*----------------------------------------------------------------------*/ /* * This section contains code to support the use of the ASC as a * generic serial port. */ static inline unsigned asc_hw_txroom(struct uart_port *port) { u32 status = asc_in(port, ASC_STA); if (status & ASC_STA_THE) return port->fifosize / 2; else if (!(status & ASC_STA_TF)) return 1; return 0; } /* * Start transmitting chars. * This is called from both interrupt and task level. * Either way interrupts are disabled. */ static void asc_transmit_chars(struct uart_port *port) { struct circ_buf *xmit = &port->state->xmit; int txroom; unsigned char c; txroom = asc_hw_txroom(port); if ((txroom != 0) && port->x_char) { c = port->x_char; port->x_char = 0; asc_out(port, ASC_TXBUF, c); port->icount.tx++; txroom = asc_hw_txroom(port); } if (uart_tx_stopped(port)) { /* * We should try and stop the hardware here, but I * don't think the ASC has any way to do that. */ asc_disable_tx_interrupts(port); return; } if (uart_circ_empty(xmit)) { asc_disable_tx_interrupts(port); return; } if (txroom == 0) return; do { c = xmit->buf[xmit->tail]; xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1); asc_out(port, ASC_TXBUF, c); port->icount.tx++; txroom--; } while ((txroom > 0) && (!uart_circ_empty(xmit))); if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS) uart_write_wakeup(port); if (uart_circ_empty(xmit)) asc_disable_tx_interrupts(port); } static void asc_receive_chars(struct uart_port *port) { struct tty_port *tport = &port->state->port; unsigned long status; unsigned long c = 0; char flag; if (port->irq_wake) pm_wakeup_event(tport->tty->dev, 0); while ((status = asc_in(port, ASC_STA)) & ASC_STA_RBF) { c = asc_in(port, ASC_RXBUF) | ASC_RXBUF_DUMMY_RX; flag = TTY_NORMAL; port->icount.rx++; if ((c & (ASC_RXBUF_FE | ASC_RXBUF_PE)) || status & ASC_STA_OE) { if (c & ASC_RXBUF_FE) { if (c == (ASC_RXBUF_FE | ASC_RXBUF_DUMMY_RX)) { port->icount.brk++; if (uart_handle_break(port)) continue; c |= ASC_RXBUF_DUMMY_BE; } else { port->icount.frame++; } } else if (c & ASC_RXBUF_PE) { port->icount.parity++; } /* * Reading any data from the RX FIFO clears the * overflow error condition. */ if (status & ASC_STA_OE) { port->icount.overrun++; c |= ASC_RXBUF_DUMMY_OE; } c &= port->read_status_mask; if (c & ASC_RXBUF_DUMMY_BE) flag = TTY_BREAK; else if (c & ASC_RXBUF_PE) flag = TTY_PARITY; else if (c & ASC_RXBUF_FE) flag = TTY_FRAME; } if (uart_handle_sysrq_char(port, c & 0xff)) continue; uart_insert_char(port, c, ASC_RXBUF_DUMMY_OE, c & 0xff, flag); } /* Tell the rest of the system the news. New characters! */ tty_flip_buffer_push(tport); } static irqreturn_t asc_interrupt(int irq, void *ptr) { struct uart_port *port = ptr; u32 status; spin_lock(&port->lock); status = asc_in(port, ASC_STA); if (status & ASC_STA_RBF) { /* Receive FIFO not empty */ asc_receive_chars(port); } if ((status & ASC_STA_THE) && (asc_in(port, ASC_INTEN) & ASC_INTEN_THE)) { /* Transmitter FIFO at least half empty */ asc_transmit_chars(port); } spin_unlock(&port->lock); return IRQ_HANDLED; } /*----------------------------------------------------------------------*/ /* * UART Functions */ static unsigned int asc_tx_empty(struct uart_port *port) { return asc_txfifo_is_empty(port) ? TIOCSER_TEMT : 0; } static void asc_set_mctrl(struct uart_port *port, unsigned int mctrl) { /* * This routine is used for seting signals of: DTR, DCD, CTS/RTS * We use ASC's hardware for CTS/RTS, so don't need any for that. * Some boards have DTR and DCD implemented using PIO pins, * code to do this should be hooked in here. */ } static unsigned int asc_get_mctrl(struct uart_port *port) { /* * This routine is used for geting signals of: DTR, DCD, DSR, RI, * and CTS/RTS */ return TIOCM_CAR | TIOCM_DSR | TIOCM_CTS; } /* There are probably characters waiting to be transmitted. */ static void asc_start_tx(struct uart_port *port) { struct circ_buf *xmit = &port->state->xmit; if (!uart_circ_empty(xmit)) asc_enable_tx_interrupts(port); } /* Transmit stop */ static void asc_stop_tx(struct uart_port *port) { asc_disable_tx_interrupts(port); } /* Receive stop */ static void asc_stop_rx(struct uart_port *port) { asc_disable_rx_interrupts(port); } /* Handle breaks - ignored by us */ static void asc_break_ctl(struct uart_port *port, int break_state) { /* Nothing here yet .. */ } /* * Enable port for reception. */ static int asc_startup(struct uart_port *port) { if (request_irq(port->irq, asc_interrupt, IRQF_NO_SUSPEND, asc_port_name(port), port)) { dev_err(port->dev, "cannot allocate irq.\n"); return -ENODEV; } asc_transmit_chars(port); asc_enable_rx_interrupts(port); return 0; } static void asc_shutdown(struct uart_port *port) { asc_disable_tx_interrupts(port); asc_disable_rx_interrupts(port); free_irq(port->irq, port); } static void asc_pm(struct uart_port *port, unsigned int state, unsigned int oldstate) { struct asc_port *ascport = to_asc_port(port); unsigned long flags = 0; u32 ctl; switch (state) { case UART_PM_STATE_ON: clk_prepare_enable(ascport->clk); break; case UART_PM_STATE_OFF: /* * Disable the ASC baud rate generator, which is as close as * we can come to turning it off. Note this is not called with * the port spinlock held. */ spin_lock_irqsave(&port->lock, flags); ctl = asc_in(port, ASC_CTL) & ~ASC_CTL_RUN; asc_out(port, ASC_CTL, ctl); spin_unlock_irqrestore(&port->lock, flags); clk_disable_unprepare(ascport->clk); break; } } static void asc_set_termios(struct uart_port *port, struct ktermios *termios, struct ktermios *old) { struct asc_port *ascport = to_asc_port(port); unsigned int baud; u32 ctrl_val; tcflag_t cflag; unsigned long flags; /* Update termios to reflect hardware capabilities */ termios->c_cflag &= ~(CMSPAR | (ascport->hw_flow_control ? 0 : CRTSCTS)); port->uartclk = clk_get_rate(ascport->clk); baud = uart_get_baud_rate(port, termios, old, 0, port->uartclk/16); cflag = termios->c_cflag; spin_lock_irqsave(&port->lock, flags); /* read control register */ ctrl_val = asc_in(port, ASC_CTL); /* stop serial port and reset value */ asc_out(port, ASC_CTL, (ctrl_val & ~ASC_CTL_RUN)); ctrl_val = ASC_CTL_RXENABLE | ASC_CTL_FIFOENABLE; /* reset fifo rx & tx */ asc_out(port, ASC_TXRESET, 1); asc_out(port, ASC_RXRESET, 1); /* set character length */ if ((cflag & CSIZE) == CS7) { ctrl_val |= ASC_CTL_MODE_7BIT_PAR; } else { ctrl_val |= (cflag & PARENB) ? ASC_CTL_MODE_8BIT_PAR : ASC_CTL_MODE_8BIT; } /* set stop bit */ ctrl_val |= (cflag & CSTOPB) ? ASC_CTL_STOP_2BIT : ASC_CTL_STOP_1BIT; /* odd parity */ if (cflag & PARODD) ctrl_val |= ASC_CTL_PARITYODD; /* hardware flow control */ if ((cflag & CRTSCTS)) ctrl_val |= ASC_CTL_CTSENABLE; if ((baud < 19200) && !ascport->force_m1) { asc_out(port, ASC_BAUDRATE, (port->uartclk / (16 * baud))); } else { /* * MODE 1: recommended for high bit rates (above 19.2K) * * baudrate * 16 * 2^16 * ASCBaudRate = ------------------------ * inputclock * * To keep maths inside 64bits, we divide inputclock by 16. */ u64 dividend = (u64)baud * (1 << 16); do_div(dividend, port->uartclk / 16); asc_out(port, ASC_BAUDRATE, dividend); ctrl_val |= ASC_CTL_BAUDMODE; } uart_update_timeout(port, cflag, baud); ascport->port.read_status_mask = ASC_RXBUF_DUMMY_OE; if (termios->c_iflag & INPCK) ascport->port.read_status_mask |= ASC_RXBUF_FE | ASC_RXBUF_PE; if (termios->c_iflag & (IGNBRK | BRKINT | PARMRK)) ascport->port.read_status_mask |= ASC_RXBUF_DUMMY_BE; /* * Characters to ignore */ ascport->port.ignore_status_mask = 0; if (termios->c_iflag & IGNPAR) ascport->port.ignore_status_mask |= ASC_RXBUF_FE | ASC_RXBUF_PE; if (termios->c_iflag & IGNBRK) { ascport->port.ignore_status_mask |= ASC_RXBUF_DUMMY_BE; /* * If we're ignoring parity and break indicators, * ignore overruns too (for real raw support). */ if (termios->c_iflag & IGNPAR) ascport->port.ignore_status_mask |= ASC_RXBUF_DUMMY_OE; } /* * Ignore all characters if CREAD is not set. */ if (!(termios->c_cflag & CREAD)) ascport->port.ignore_status_mask |= ASC_RXBUF_DUMMY_RX; /* Set the timeout */ asc_out(port, ASC_TIMEOUT, 20); /* write final value and enable port */ asc_out(port, ASC_CTL, (ctrl_val | ASC_CTL_RUN)); spin_unlock_irqrestore(&port->lock, flags); } static const char *asc_type(struct uart_port *port) { return (port->type == PORT_ASC) ? DRIVER_NAME : NULL; } static void asc_release_port(struct uart_port *port) { } static int asc_request_port(struct uart_port *port) { return 0; } /* * Called when the port is opened, and UPF_BOOT_AUTOCONF flag is set * Set type field if successful */ static void asc_config_port(struct uart_port *port, int flags) { if ((flags & UART_CONFIG_TYPE)) port->type = PORT_ASC; } static int asc_verify_port(struct uart_port *port, struct serial_struct *ser) { /* No user changeable parameters */ return -EINVAL; } #ifdef CONFIG_CONSOLE_POLL /* * Console polling routines for writing and reading from the uart while * in an interrupt or debug context (i.e. kgdb). */ static int asc_get_poll_char(struct uart_port *port) { if (!(asc_in(port, ASC_STA) & ASC_STA_RBF)) return NO_POLL_CHAR; return asc_in(port, ASC_RXBUF); } static void asc_put_poll_char(struct uart_port *port, unsigned char c) { while (!asc_txfifo_is_half_empty(port)) cpu_relax(); asc_out(port, ASC_TXBUF, c); } #endif /* CONFIG_CONSOLE_POLL */ /*---------------------------------------------------------------------*/ static struct uart_ops asc_uart_ops = { .tx_empty = asc_tx_empty, .set_mctrl = asc_set_mctrl, .get_mctrl = asc_get_mctrl, .start_tx = asc_start_tx, .stop_tx = asc_stop_tx, .stop_rx = asc_stop_rx, .break_ctl = asc_break_ctl, .startup = asc_startup, .shutdown = asc_shutdown, .set_termios = asc_set_termios, .type = asc_type, .release_port = asc_release_port, .request_port = asc_request_port, .config_port = asc_config_port, .verify_port = asc_verify_port, .pm = asc_pm, #ifdef CONFIG_CONSOLE_POLL .poll_get_char = asc_get_poll_char, .poll_put_char = asc_put_poll_char, #endif /* CONFIG_CONSOLE_POLL */ }; static int asc_init_port(struct asc_port *ascport, struct platform_device *pdev) { struct uart_port *port = &ascport->port; struct resource *res; port->iotype = UPIO_MEM; port->flags = UPF_BOOT_AUTOCONF; port->ops = &asc_uart_ops; port->fifosize = ASC_FIFO_SIZE; port->dev = &pdev->dev; port->irq = platform_get_irq(pdev, 0); res = platform_get_resource(pdev, IORESOURCE_MEM, 0); port->membase = devm_ioremap_resource(&pdev->dev, res); if (IS_ERR(port->membase)) return PTR_ERR(port->membase); port->mapbase = res->start; spin_lock_init(&port->lock); ascport->clk = devm_clk_get(&pdev->dev, NULL); if (WARN_ON(IS_ERR(ascport->clk))) return -EINVAL; /* ensure that clk rate is correct by enabling the clk */ clk_prepare_enable(ascport->clk); ascport->port.uartclk = clk_get_rate(ascport->clk); WARN_ON(ascport->port.uartclk == 0); clk_disable_unprepare(ascport->clk); return 0; } static struct asc_port *asc_of_get_asc_port(struct platform_device *pdev) { struct device_node *np = pdev->dev.of_node; int id; if (!np) return NULL; id = of_alias_get_id(np, ASC_SERIAL_NAME); if (id < 0) id = 0; if (WARN_ON(id >= ASC_MAX_PORTS)) return NULL; asc_ports[id].hw_flow_control = of_property_read_bool(np, "st,hw-flow-control"); asc_ports[id].force_m1 = of_property_read_bool(np, "st,force_m1"); asc_ports[id].port.line = id; return &asc_ports[id]; } #ifdef CONFIG_OF static struct of_device_id asc_match[] = { { .compatible = "st,asc", }, {}, }; MODULE_DEVICE_TABLE(of, asc_match); #endif static int asc_serial_probe(struct platform_device *pdev) { int ret; struct asc_port *ascport; ascport = asc_of_get_asc_port(pdev); if (!ascport) return -ENODEV; ret = asc_init_port(ascport, pdev); if (ret) return ret; ret = uart_add_one_port(&asc_uart_driver, &ascport->port); if (ret) return ret; platform_set_drvdata(pdev, &ascport->port); return 0; } static int asc_serial_remove(struct platform_device *pdev) { struct uart_port *port = platform_get_drvdata(pdev); return uart_remove_one_port(&asc_uart_driver, port); } #ifdef CONFIG_PM_SLEEP static int asc_serial_suspend(struct device *dev) { struct platform_device *pdev = to_platform_device(dev); struct uart_port *port = platform_get_drvdata(pdev); return uart_suspend_port(&asc_uart_driver, port); } static int asc_serial_resume(struct device *dev) { struct platform_device *pdev = to_platform_device(dev); struct uart_port *port = platform_get_drvdata(pdev); return uart_resume_port(&asc_uart_driver, port); } #endif /* CONFIG_PM_SLEEP */ /*----------------------------------------------------------------------*/ #ifdef CONFIG_SERIAL_ST_ASC_CONSOLE static void asc_console_putchar(struct uart_port *port, int ch) { unsigned int timeout = 1000000; /* Wait for upto 1 second in case flow control is stopping us. */ while (--timeout && !asc_txfifo_is_half_empty(port)) udelay(1); asc_out(port, ASC_TXBUF, ch); } /* * Print a string to the serial port trying not to disturb * any possible real use of the port... */ static void asc_console_write(struct console *co, const char *s, unsigned count) { struct uart_port *port = &asc_ports[co->index].port; unsigned long flags; unsigned long timeout = 1000000; int locked = 1; u32 intenable; local_irq_save(flags); if (port->sysrq) locked = 0; /* asc_interrupt has already claimed the lock */ else if (oops_in_progress) locked = spin_trylock(&port->lock); else spin_lock(&port->lock); /* * Disable interrupts so we don't get the IRQ line bouncing * up and down while interrupts are disabled. */ intenable = asc_in(port, ASC_INTEN); asc_out(port, ASC_INTEN, 0); (void)asc_in(port, ASC_INTEN); /* Defeat bus write posting */ uart_console_write(port, s, count, asc_console_putchar); while (--timeout && !asc_txfifo_is_empty(port)) udelay(1); asc_out(port, ASC_INTEN, intenable); if (locked) spin_unlock(&port->lock); local_irq_restore(flags); } static int asc_console_setup(struct console *co, char *options) { struct asc_port *ascport; int baud = 9600; int bits = 8; int parity = 'n'; int flow = 'n'; if (co->index >= ASC_MAX_PORTS) return -ENODEV; ascport = &asc_ports[co->index]; /* * This driver does not support early console initialization * (use ARM early printk support instead), so we only expect * this to be called during the uart port registration when the * driver gets probed and the port should be mapped at that point. */ if (ascport->port.mapbase == 0 || ascport->port.membase == NULL) return -ENXIO; if (options) uart_parse_options(options, &baud, &parity, &bits, &flow); return uart_set_options(&ascport->port, co, baud, parity, bits, flow); } static struct console asc_console = { .name = ASC_SERIAL_NAME, .device = uart_console_device, .write = asc_console_write, .setup = asc_console_setup, .flags = CON_PRINTBUFFER, .index = -1, .data = &asc_uart_driver, }; #define ASC_SERIAL_CONSOLE (&asc_console) #else #define ASC_SERIAL_CONSOLE NULL #endif /* CONFIG_SERIAL_ST_ASC_CONSOLE */ static struct uart_driver asc_uart_driver = { .owner = THIS_MODULE, .driver_name = DRIVER_NAME, .dev_name = ASC_SERIAL_NAME, .major = 0, .minor = 0, .nr = ASC_MAX_PORTS, .cons = ASC_SERIAL_CONSOLE, }; static const struct dev_pm_ops asc_serial_pm_ops = { SET_SYSTEM_SLEEP_PM_OPS(asc_serial_suspend, asc_serial_resume) }; static struct platform_driver asc_serial_driver = { .probe = asc_serial_probe, .remove = asc_serial_remove, .driver = { .name = DRIVER_NAME, .pm = &asc_serial_pm_ops, .of_match_table = of_match_ptr(asc_match), }, }; static int __init asc_init(void) { int ret; static char banner[] __initdata = KERN_INFO "STMicroelectronics ASC driver initialized\n"; printk(banner); ret = uart_register_driver(&asc_uart_driver); if (ret) return ret; ret = platform_driver_register(&asc_serial_driver); if (ret) uart_unregister_driver(&asc_uart_driver); return ret; } static void __exit asc_exit(void) { platform_driver_unregister(&asc_serial_driver); uart_unregister_driver(&asc_uart_driver); } module_init(asc_init); module_exit(asc_exit); MODULE_ALIAS("platform:" DRIVER_NAME); MODULE_AUTHOR("STMicroelectronics (R&D) Limited"); MODULE_DESCRIPTION("STMicroelectronics ASC serial port driver"); MODULE_LICENSE("GPL");