/* * Serial Port driver for a NWP uart device * * Copyright (C) 2008 IBM Corp., Benjamin Krill <ben@codiert.org> * * 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. * */ #include <linux/init.h> #include <linux/export.h> #include <linux/console.h> #include <linux/serial.h> #include <linux/serial_reg.h> #include <linux/serial_core.h> #include <linux/tty.h> #include <linux/tty_flip.h> #include <linux/irqreturn.h> #include <linux/mutex.h> #include <linux/of_platform.h> #include <linux/of_device.h> #include <linux/nwpserial.h> #include <asm/prom.h> #include <asm/dcr.h> #define NWPSERIAL_NR 2 #define NWPSERIAL_STATUS_RXVALID 0x1 #define NWPSERIAL_STATUS_TXFULL 0x2 struct nwpserial_port { struct uart_port port; dcr_host_t dcr_host; unsigned int ier; unsigned int mcr; }; static DEFINE_MUTEX(nwpserial_mutex); static struct nwpserial_port nwpserial_ports[NWPSERIAL_NR]; static void wait_for_bits(struct nwpserial_port *up, int bits) { unsigned int status, tmout = 10000; /* Wait up to 10ms for the character(s) to be sent. */ do { status = dcr_read(up->dcr_host, UART_LSR); if (--tmout == 0) break; udelay(1); } while ((status & bits) != bits); } #ifdef CONFIG_SERIAL_OF_PLATFORM_NWPSERIAL_CONSOLE static void nwpserial_console_putchar(struct uart_port *port, int c) { struct nwpserial_port *up; up = container_of(port, struct nwpserial_port, port); /* check if tx buffer is full */ wait_for_bits(up, UART_LSR_THRE); dcr_write(up->dcr_host, UART_TX, c); up->port.icount.tx++; } static void nwpserial_console_write(struct console *co, const char *s, unsigned int count) { struct nwpserial_port *up = &nwpserial_ports[co->index]; unsigned long flags; int locked = 1; if (oops_in_progress) locked = spin_trylock_irqsave(&up->port.lock, flags); else spin_lock_irqsave(&up->port.lock, flags); /* save and disable interrupt */ up->ier = dcr_read(up->dcr_host, UART_IER); dcr_write(up->dcr_host, UART_IER, up->ier & ~UART_IER_RDI); uart_console_write(&up->port, s, count, nwpserial_console_putchar); /* wait for transmitter to become empty */ while ((dcr_read(up->dcr_host, UART_LSR) & UART_LSR_THRE) == 0) cpu_relax(); /* restore interrupt state */ dcr_write(up->dcr_host, UART_IER, up->ier); if (locked) spin_unlock_irqrestore(&up->port.lock, flags); } static struct uart_driver nwpserial_reg; static struct console nwpserial_console = { .name = "ttySQ", .write = nwpserial_console_write, .device = uart_console_device, .flags = CON_PRINTBUFFER, .index = -1, .data = &nwpserial_reg, }; #define NWPSERIAL_CONSOLE (&nwpserial_console) #else #define NWPSERIAL_CONSOLE NULL #endif /* CONFIG_SERIAL_OF_PLATFORM_NWPSERIAL_CONSOLE */ /**************************************************************************/ static int nwpserial_request_port(struct uart_port *port) { return 0; } static void nwpserial_release_port(struct uart_port *port) { /* N/A */ } static void nwpserial_config_port(struct uart_port *port, int flags) { port->type = PORT_NWPSERIAL; } static irqreturn_t nwpserial_interrupt(int irq, void *dev_id) { struct nwpserial_port *up = dev_id; struct tty_struct *tty = up->port.state->port.tty; irqreturn_t ret; unsigned int iir; unsigned char ch; spin_lock(&up->port.lock); /* check if the uart was the interrupt source. */ iir = dcr_read(up->dcr_host, UART_IIR); if (!iir) { ret = IRQ_NONE; goto out; } do { up->port.icount.rx++; ch = dcr_read(up->dcr_host, UART_RX); if (up->port.ignore_status_mask != NWPSERIAL_STATUS_RXVALID) tty_insert_flip_char(tty, ch, TTY_NORMAL); } while (dcr_read(up->dcr_host, UART_LSR) & UART_LSR_DR); tty_flip_buffer_push(tty); ret = IRQ_HANDLED; /* clear interrupt */ dcr_write(up->dcr_host, UART_IIR, 1); out: spin_unlock(&up->port.lock); return ret; } static int nwpserial_startup(struct uart_port *port) { struct nwpserial_port *up; int err; up = container_of(port, struct nwpserial_port, port); /* disable flow control by default */ up->mcr = dcr_read(up->dcr_host, UART_MCR) & ~UART_MCR_AFE; dcr_write(up->dcr_host, UART_MCR, up->mcr); /* register interrupt handler */ err = request_irq(up->port.irq, nwpserial_interrupt, IRQF_SHARED, "nwpserial", up); if (err) return err; /* enable interrupts */ up->ier = UART_IER_RDI; dcr_write(up->dcr_host, UART_IER, up->ier); /* enable receiving */ up->port.ignore_status_mask &= ~NWPSERIAL_STATUS_RXVALID; return 0; } static void nwpserial_shutdown(struct uart_port *port) { struct nwpserial_port *up; up = container_of(port, struct nwpserial_port, port); /* disable receiving */ up->port.ignore_status_mask |= NWPSERIAL_STATUS_RXVALID; /* disable interrupts from this port */ up->ier = 0; dcr_write(up->dcr_host, UART_IER, up->ier); /* free irq */ free_irq(up->port.irq, port); } static int nwpserial_verify_port(struct uart_port *port, struct serial_struct *ser) { return -EINVAL; } static const char *nwpserial_type(struct uart_port *port) { return port->type == PORT_NWPSERIAL ? "nwpserial" : NULL; } static void nwpserial_set_termios(struct uart_port *port, struct ktermios *termios, struct ktermios *old) { struct nwpserial_port *up; up = container_of(port, struct nwpserial_port, port); up->port.read_status_mask = NWPSERIAL_STATUS_RXVALID | NWPSERIAL_STATUS_TXFULL; up->port.ignore_status_mask = 0; /* ignore all characters if CREAD is not set */ if ((termios->c_cflag & CREAD) == 0) up->port.ignore_status_mask |= NWPSERIAL_STATUS_RXVALID; /* Copy back the old hardware settings */ if (old) tty_termios_copy_hw(termios, old); } static void nwpserial_break_ctl(struct uart_port *port, int ctl) { /* N/A */ } static void nwpserial_enable_ms(struct uart_port *port) { /* N/A */ } static void nwpserial_stop_rx(struct uart_port *port) { struct nwpserial_port *up; up = container_of(port, struct nwpserial_port, port); /* don't forward any more data (like !CREAD) */ up->port.ignore_status_mask = NWPSERIAL_STATUS_RXVALID; } static void nwpserial_putchar(struct nwpserial_port *up, unsigned char c) { /* check if tx buffer is full */ wait_for_bits(up, UART_LSR_THRE); dcr_write(up->dcr_host, UART_TX, c); up->port.icount.tx++; } static void nwpserial_start_tx(struct uart_port *port) { struct nwpserial_port *up; struct circ_buf *xmit; up = container_of(port, struct nwpserial_port, port); xmit = &up->port.state->xmit; if (port->x_char) { nwpserial_putchar(up, up->port.x_char); port->x_char = 0; } while (!(uart_circ_empty(xmit) || uart_tx_stopped(&up->port))) { nwpserial_putchar(up, xmit->buf[xmit->tail]); xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE-1); } } static unsigned int nwpserial_get_mctrl(struct uart_port *port) { return 0; } static void nwpserial_set_mctrl(struct uart_port *port, unsigned int mctrl) { /* N/A */ } static void nwpserial_stop_tx(struct uart_port *port) { /* N/A */ } static unsigned int nwpserial_tx_empty(struct uart_port *port) { struct nwpserial_port *up; unsigned long flags; int ret; up = container_of(port, struct nwpserial_port, port); spin_lock_irqsave(&up->port.lock, flags); ret = dcr_read(up->dcr_host, UART_LSR); spin_unlock_irqrestore(&up->port.lock, flags); return ret & UART_LSR_TEMT ? TIOCSER_TEMT : 0; } static struct uart_ops nwpserial_pops = { .tx_empty = nwpserial_tx_empty, .set_mctrl = nwpserial_set_mctrl, .get_mctrl = nwpserial_get_mctrl, .stop_tx = nwpserial_stop_tx, .start_tx = nwpserial_start_tx, .stop_rx = nwpserial_stop_rx, .enable_ms = nwpserial_enable_ms, .break_ctl = nwpserial_break_ctl, .startup = nwpserial_startup, .shutdown = nwpserial_shutdown, .set_termios = nwpserial_set_termios, .type = nwpserial_type, .release_port = nwpserial_release_port, .request_port = nwpserial_request_port, .config_port = nwpserial_config_port, .verify_port = nwpserial_verify_port, }; static struct uart_driver nwpserial_reg = { .owner = THIS_MODULE, .driver_name = "nwpserial", .dev_name = "ttySQ", .major = TTY_MAJOR, .minor = 68, .nr = NWPSERIAL_NR, .cons = NWPSERIAL_CONSOLE, }; int nwpserial_register_port(struct uart_port *port) { struct nwpserial_port *up = NULL; int ret = -1; int i; static int first = 1; int dcr_len; int dcr_base; struct device_node *dn; mutex_lock(&nwpserial_mutex); dn = port->dev->of_node; if (dn == NULL) goto out; /* get dcr base. */ dcr_base = dcr_resource_start(dn, 0); /* find matching entry */ for (i = 0; i < NWPSERIAL_NR; i++) if (nwpserial_ports[i].port.iobase == dcr_base) { up = &nwpserial_ports[i]; break; } /* we didn't find a mtching entry, search for a free port */ if (up == NULL) for (i = 0; i < NWPSERIAL_NR; i++) if (nwpserial_ports[i].port.type == PORT_UNKNOWN && nwpserial_ports[i].port.iobase == 0) { up = &nwpserial_ports[i]; break; } if (up == NULL) { ret = -EBUSY; goto out; } if (first) uart_register_driver(&nwpserial_reg); first = 0; up->port.membase = port->membase; up->port.irq = port->irq; up->port.uartclk = port->uartclk; up->port.fifosize = port->fifosize; up->port.regshift = port->regshift; up->port.iotype = port->iotype; up->port.flags = port->flags; up->port.mapbase = port->mapbase; up->port.private_data = port->private_data; if (port->dev) up->port.dev = port->dev; if (up->port.iobase != dcr_base) { up->port.ops = &nwpserial_pops; up->port.fifosize = 16; spin_lock_init(&up->port.lock); up->port.iobase = dcr_base; dcr_len = dcr_resource_len(dn, 0); up->dcr_host = dcr_map(dn, dcr_base, dcr_len); if (!DCR_MAP_OK(up->dcr_host)) { printk(KERN_ERR "Cannot map DCR resources for NWPSERIAL"); goto out; } } ret = uart_add_one_port(&nwpserial_reg, &up->port); if (ret == 0) ret = up->port.line; out: mutex_unlock(&nwpserial_mutex); return ret; } EXPORT_SYMBOL(nwpserial_register_port); void nwpserial_unregister_port(int line) { struct nwpserial_port *up = &nwpserial_ports[line]; mutex_lock(&nwpserial_mutex); uart_remove_one_port(&nwpserial_reg, &up->port); up->port.type = PORT_UNKNOWN; mutex_unlock(&nwpserial_mutex); } EXPORT_SYMBOL(nwpserial_unregister_port); #ifdef CONFIG_SERIAL_OF_PLATFORM_NWPSERIAL_CONSOLE static int __init nwpserial_console_init(void) { struct nwpserial_port *up = NULL; struct device_node *dn; const char *name; int dcr_base; int dcr_len; int i; /* search for a free port */ for (i = 0; i < NWPSERIAL_NR; i++) if (nwpserial_ports[i].port.type == PORT_UNKNOWN) { up = &nwpserial_ports[i]; break; } if (up == NULL) return -1; name = of_get_property(of_chosen, "linux,stdout-path", NULL); if (name == NULL) return -1; dn = of_find_node_by_path(name); if (!dn) return -1; spin_lock_init(&up->port.lock); up->port.ops = &nwpserial_pops; up->port.type = PORT_NWPSERIAL; up->port.fifosize = 16; dcr_base = dcr_resource_start(dn, 0); dcr_len = dcr_resource_len(dn, 0); up->port.iobase = dcr_base; up->dcr_host = dcr_map(dn, dcr_base, dcr_len); if (!DCR_MAP_OK(up->dcr_host)) { printk("Cannot map DCR resources for SERIAL"); return -1; } register_console(&nwpserial_console); return 0; } console_initcall(nwpserial_console_init); #endif /* CONFIG_SERIAL_OF_PLATFORM_NWPSERIAL_CONSOLE */