diff options
Diffstat (limited to 'drivers/tty/metag_da.c')
| -rw-r--r-- | drivers/tty/metag_da.c | 677 |
1 files changed, 677 insertions, 0 deletions
diff --git a/drivers/tty/metag_da.c b/drivers/tty/metag_da.c new file mode 100644 index 00000000000..7332e2ca461 --- /dev/null +++ b/drivers/tty/metag_da.c @@ -0,0 +1,677 @@ +/* + * dashtty.c - tty driver for Dash channels interface. + * + * Copyright (C) 2007,2008,2012 Imagination Technologies + * + * This file is subject to the terms and conditions of the GNU General Public + * License. See the file COPYING in the main directory of this archive + * for more details. + * + */ + +#include <linux/atomic.h> +#include <linux/completion.h> +#include <linux/console.h> +#include <linux/delay.h> +#include <linux/export.h> +#include <linux/init.h> +#include <linux/kernel.h> +#include <linux/kthread.h> +#include <linux/mutex.h> +#include <linux/sched.h> +#include <linux/serial.h> +#include <linux/slab.h> +#include <linux/spinlock.h> +#include <linux/string.h> +#include <linux/timer.h> +#include <linux/tty.h> +#include <linux/tty_driver.h> +#include <linux/tty_flip.h> +#include <linux/uaccess.h> + +#include <asm/da.h> + +/* Channel error codes */ +#define CONAOK 0 +#define CONERR 1 +#define CONBAD 2 +#define CONPRM 3 +#define CONADR 4 +#define CONCNT 5 +#define CONCBF 6 +#define CONCBE 7 +#define CONBSY 8 + +/* Default channel for the console */ +#define CONSOLE_CHANNEL 1 + +#define NUM_TTY_CHANNELS 6 + +/* Auto allocate */ +#define DA_TTY_MAJOR 0 + +/* A speedy poll rate helps the userland debug process connection response. + * But, if you set it too high then no other userland processes get much + * of a look in. + */ +#define DA_TTY_POLL (HZ / 50) + +/* + * A short put delay improves latency but has a high throughput overhead + */ +#define DA_TTY_PUT_DELAY (HZ / 100) + +static atomic_t num_channels_need_poll = ATOMIC_INIT(0); + +static struct timer_list poll_timer; + +static struct tty_driver *channel_driver; + +static struct timer_list put_timer; +static struct task_struct *dashtty_thread; + +#define RX_BUF_SIZE 1024 + +enum { + INCHR = 1, + OUTCHR, + RDBUF, + WRBUF, + RDSTAT +}; + +/** + * struct dashtty_port - Wrapper struct for dashtty tty_port. + * @port: TTY port data + * @rx_lock: Lock for rx_buf. + * This protects between the poll timer and user context. + * It's also held during read SWITCH operations. + * @rx_buf: Read buffer + * @xmit_lock: Lock for xmit_*, and port.xmit_buf. + * This protects between user context and kernel thread. + * It's also held during write SWITCH operations. + * @xmit_cnt: Size of xmit buffer contents + * @xmit_head: Head of xmit buffer where data is written + * @xmit_tail: Tail of xmit buffer where data is read + * @xmit_empty: Completion for xmit buffer being empty + */ +struct dashtty_port { + struct tty_port port; + spinlock_t rx_lock; + void *rx_buf; + struct mutex xmit_lock; + unsigned int xmit_cnt; + unsigned int xmit_head; + unsigned int xmit_tail; + struct completion xmit_empty; +}; + +static struct dashtty_port dashtty_ports[NUM_TTY_CHANNELS]; + +static atomic_t dashtty_xmit_cnt = ATOMIC_INIT(0); +static wait_queue_head_t dashtty_waitqueue; + +/* + * Low-level DA channel access routines + */ +static int chancall(int in_bios_function, int in_channel, + int in_arg2, void *in_arg3, + void *in_arg4) +{ + register int bios_function asm("D1Ar1") = in_bios_function; + register int channel asm("D0Ar2") = in_channel; + register int arg2 asm("D1Ar3") = in_arg2; + register void *arg3 asm("D0Ar4") = in_arg3; + register void *arg4 asm("D1Ar5") = in_arg4; + register int bios_call asm("D0Ar6") = 3; + register int result asm("D0Re0"); + + asm volatile ( + "MSETL [A0StP++], %6,%4,%2\n\t" + "ADD A0StP, A0StP, #8\n\t" + "SWITCH #0x0C30208\n\t" + "GETD %0, [A0StP+#-8]\n\t" + "SUB A0StP, A0StP, #(4*6)+8\n\t" + : "=d" (result) /* outs */ + : "d" (bios_function), + "d" (channel), + "d" (arg2), + "d" (arg3), + "d" (arg4), + "d" (bios_call) /* ins */ + : "memory"); + + return result; +} + +/* + * Attempts to fetch count bytes from channel and returns actual count. + */ +static int fetch_data(unsigned int channel) +{ + struct dashtty_port *dport = &dashtty_ports[channel]; + int received = 0; + + spin_lock_bh(&dport->rx_lock); + /* check the port isn't being shut down */ + if (!dport->rx_buf) + goto unlock; + if (chancall(RDBUF, channel, RX_BUF_SIZE, + (void *)dport->rx_buf, &received) == CONAOK) { + if (received) { + int space; + unsigned char *cbuf; + + space = tty_prepare_flip_string(&dport->port, &cbuf, + received); + + if (space <= 0) + goto unlock; + + memcpy(cbuf, dport->rx_buf, space); + tty_flip_buffer_push(&dport->port); + } + } +unlock: + spin_unlock_bh(&dport->rx_lock); + + return received; +} + +/** + * find_channel_to_poll() - Returns number of the next channel to poll. + * Returns: The number of the next channel to poll, or -1 if none need + * polling. + */ +static int find_channel_to_poll(void) +{ + static int last_polled_channel; + int last = last_polled_channel; + int chan; + struct dashtty_port *dport; + + for (chan = last + 1; ; ++chan) { + if (chan >= NUM_TTY_CHANNELS) + chan = 0; + + dport = &dashtty_ports[chan]; + if (dport->rx_buf) { + last_polled_channel = chan; + return chan; + } + + if (chan == last) + break; + } + return -1; +} + +/** + * put_channel_data() - Write out a block of channel data. + * @chan: DA channel number. + * + * Write a single block of data out to the debug adapter. If the circular buffer + * is wrapped then only the first block is written. + * + * Returns: 1 if the remote buffer was too full to accept data. + * 0 otherwise. + */ +static int put_channel_data(unsigned int chan) +{ + struct dashtty_port *dport; + struct tty_struct *tty; + int number_written; + unsigned int count = 0; + + dport = &dashtty_ports[chan]; + mutex_lock(&dport->xmit_lock); + if (dport->xmit_cnt) { + count = min((unsigned int)(SERIAL_XMIT_SIZE - dport->xmit_tail), + dport->xmit_cnt); + chancall(WRBUF, chan, count, + dport->port.xmit_buf + dport->xmit_tail, + &number_written); + dport->xmit_cnt -= number_written; + if (!dport->xmit_cnt) { + /* reset pointers to avoid wraps */ + dport->xmit_head = 0; + dport->xmit_tail = 0; + complete(&dport->xmit_empty); + } else { + dport->xmit_tail += number_written; + if (dport->xmit_tail >= SERIAL_XMIT_SIZE) + dport->xmit_tail -= SERIAL_XMIT_SIZE; + } + atomic_sub(number_written, &dashtty_xmit_cnt); + } + mutex_unlock(&dport->xmit_lock); + + /* if we've made more data available, wake up tty */ + if (count && number_written) { + tty = tty_port_tty_get(&dport->port); + if (tty) { + tty_wakeup(tty); + tty_kref_put(tty); + } + } + + /* did the write fail? */ + return count && !number_written; +} + +/** + * put_data() - Kernel thread to write out blocks of channel data to DA. + * @arg: Unused. + * + * This kernel thread runs while @dashtty_xmit_cnt != 0, and loops over the + * channels to write out any buffered data. If any of the channels stall due to + * the remote buffer being full, a hold off happens to allow the debugger to + * drain the buffer. + */ +static int put_data(void *arg) +{ + unsigned int chan, stall; + + __set_current_state(TASK_RUNNING); + while (!kthread_should_stop()) { + /* + * For each channel see if there's anything to transmit in the + * port's xmit_buf. + */ + stall = 0; + for (chan = 0; chan < NUM_TTY_CHANNELS; ++chan) + stall += put_channel_data(chan); + + /* + * If some of the buffers are full, hold off for a short while + * to allow them to empty. + */ + if (stall) + msleep(25); + + wait_event_interruptible(dashtty_waitqueue, + atomic_read(&dashtty_xmit_cnt)); + } + + return 0; +} + +/* + * This gets called every DA_TTY_POLL and polls the channels for data + */ +static void dashtty_timer(unsigned long ignored) +{ + int channel; + + /* If there are no ports open do nothing and don't poll again. */ + if (!atomic_read(&num_channels_need_poll)) + return; + + channel = find_channel_to_poll(); + + /* Did we find a channel to poll? */ + if (channel >= 0) + fetch_data(channel); + + mod_timer_pinned(&poll_timer, jiffies + DA_TTY_POLL); +} + +static void add_poll_timer(struct timer_list *poll_timer) +{ + setup_timer(poll_timer, dashtty_timer, 0); + poll_timer->expires = jiffies + DA_TTY_POLL; + + /* + * Always attach the timer to the boot CPU. The DA channels are per-CPU + * so all polling should be from a single CPU. + */ + add_timer_on(poll_timer, 0); +} + +static int dashtty_port_activate(struct tty_port *port, struct tty_struct *tty) +{ + struct dashtty_port *dport = container_of(port, struct dashtty_port, + port); + void *rx_buf; + + /* Allocate the buffer we use for writing data */ + if (tty_port_alloc_xmit_buf(port) < 0) + goto err; + + /* Allocate the buffer we use for reading data */ + rx_buf = kzalloc(RX_BUF_SIZE, GFP_KERNEL); + if (!rx_buf) + goto err_free_xmit; + + spin_lock_bh(&dport->rx_lock); + dport->rx_buf = rx_buf; + spin_unlock_bh(&dport->rx_lock); + + /* + * Don't add the poll timer if we're opening a console. This + * avoids the overhead of polling the Dash but means it is not + * possible to have a login on /dev/console. + * + */ + if (dport != &dashtty_ports[CONSOLE_CHANNEL]) + if (atomic_inc_return(&num_channels_need_poll) == 1) + add_poll_timer(&poll_timer); + + return 0; +err_free_xmit: + tty_port_free_xmit_buf(port); +err: + return -ENOMEM; +} + +static void dashtty_port_shutdown(struct tty_port *port) +{ + struct dashtty_port *dport = container_of(port, struct dashtty_port, + port); + void *rx_buf; + unsigned int count; + + /* stop reading */ + if (dport != &dashtty_ports[CONSOLE_CHANNEL]) + if (atomic_dec_and_test(&num_channels_need_poll)) + del_timer_sync(&poll_timer); + + mutex_lock(&dport->xmit_lock); + count = dport->xmit_cnt; + mutex_unlock(&dport->xmit_lock); + if (count) { + /* + * There's still data to write out, so wake and wait for the + * writer thread to drain the buffer. + */ + del_timer(&put_timer); + wake_up_interruptible(&dashtty_waitqueue); + wait_for_completion(&dport->xmit_empty); + } + + /* Null the read buffer (timer could still be running!) */ + spin_lock_bh(&dport->rx_lock); + rx_buf = dport->rx_buf; + dport->rx_buf = NULL; + spin_unlock_bh(&dport->rx_lock); + /* Free the read buffer */ + kfree(rx_buf); + + /* Free the write buffer */ + tty_port_free_xmit_buf(port); +} + +static const struct tty_port_operations dashtty_port_ops = { + .activate = dashtty_port_activate, + .shutdown = dashtty_port_shutdown, +}; + +static int dashtty_install(struct tty_driver *driver, struct tty_struct *tty) +{ + return tty_port_install(&dashtty_ports[tty->index].port, driver, tty); +} + +static int dashtty_open(struct tty_struct *tty, struct file *filp) +{ + return tty_port_open(tty->port, tty, filp); +} + +static void dashtty_close(struct tty_struct *tty, struct file *filp) +{ + return tty_port_close(tty->port, tty, filp); +} + +static void dashtty_hangup(struct tty_struct *tty) +{ + int channel; + struct dashtty_port *dport; + + channel = tty->index; + dport = &dashtty_ports[channel]; + + /* drop any data in the xmit buffer */ + mutex_lock(&dport->xmit_lock); + if (dport->xmit_cnt) { + atomic_sub(dport->xmit_cnt, &dashtty_xmit_cnt); + dport->xmit_cnt = 0; + dport->xmit_head = 0; + dport->xmit_tail = 0; + complete(&dport->xmit_empty); + } + mutex_unlock(&dport->xmit_lock); + + tty_port_hangup(tty->port); +} + +/** + * dashtty_put_timer() - Delayed wake up of kernel thread. + * @ignored: unused + * + * This timer function wakes up the kernel thread if any data exists in the + * buffers. It is used to delay the expensive writeout until the writer has + * stopped writing. + */ +static void dashtty_put_timer(unsigned long ignored) +{ + if (atomic_read(&dashtty_xmit_cnt)) + wake_up_interruptible(&dashtty_waitqueue); +} + +static int dashtty_write(struct tty_struct *tty, const unsigned char *buf, + int total) +{ + int channel, count, block; + struct dashtty_port *dport; + + /* Determine the channel */ + channel = tty->index; + dport = &dashtty_ports[channel]; + + /* + * Write to output buffer. + * + * The reason that we asynchronously write the buffer is because if we + * were to write the buffer synchronously then because DA channels are + * per-CPU the buffer would be written to the channel of whatever CPU + * we're running on. + * + * What we actually want to happen is have all input and output done on + * one CPU. + */ + mutex_lock(&dport->xmit_lock); + /* work out how many bytes we can write to the xmit buffer */ + total = min(total, (int)(SERIAL_XMIT_SIZE - dport->xmit_cnt)); + atomic_add(total, &dashtty_xmit_cnt); + dport->xmit_cnt += total; + /* write the actual bytes (may need splitting if it wraps) */ + for (count = total; count; count -= block) { + block = min(count, (int)(SERIAL_XMIT_SIZE - dport->xmit_head)); + memcpy(dport->port.xmit_buf + dport->xmit_head, buf, block); + dport->xmit_head += block; + if (dport->xmit_head >= SERIAL_XMIT_SIZE) + dport->xmit_head -= SERIAL_XMIT_SIZE; + buf += block; + } + count = dport->xmit_cnt; + /* xmit buffer no longer empty? */ + if (count) + reinit_completion(&dport->xmit_empty); + mutex_unlock(&dport->xmit_lock); + + if (total) { + /* + * If the buffer is full, wake up the kthread, otherwise allow + * some more time for the buffer to fill up a bit before waking + * it. + */ + if (count == SERIAL_XMIT_SIZE) { + del_timer(&put_timer); + wake_up_interruptible(&dashtty_waitqueue); + } else { + mod_timer(&put_timer, jiffies + DA_TTY_PUT_DELAY); + } + } + return total; +} + +static int dashtty_write_room(struct tty_struct *tty) +{ + struct dashtty_port *dport; + int channel; + int room; + + channel = tty->index; + dport = &dashtty_ports[channel]; + + /* report the space in the xmit buffer */ + mutex_lock(&dport->xmit_lock); + room = SERIAL_XMIT_SIZE - dport->xmit_cnt; + mutex_unlock(&dport->xmit_lock); + + return room; +} + +static int dashtty_chars_in_buffer(struct tty_struct *tty) +{ + struct dashtty_port *dport; + int channel; + int chars; + + channel = tty->index; + dport = &dashtty_ports[channel]; + + /* report the number of bytes in the xmit buffer */ + mutex_lock(&dport->xmit_lock); + chars = dport->xmit_cnt; + mutex_unlock(&dport->xmit_lock); + + return chars; +} + +static const struct tty_operations dashtty_ops = { + .install = dashtty_install, + .open = dashtty_open, + .close = dashtty_close, + .hangup = dashtty_hangup, + .write = dashtty_write, + .write_room = dashtty_write_room, + .chars_in_buffer = dashtty_chars_in_buffer, +}; + +static int __init dashtty_init(void) +{ + int ret; + int nport; + struct dashtty_port *dport; + + if (!metag_da_enabled()) + return -ENODEV; + + channel_driver = tty_alloc_driver(NUM_TTY_CHANNELS, + TTY_DRIVER_REAL_RAW); + if (IS_ERR(channel_driver)) + return PTR_ERR(channel_driver); + + channel_driver->driver_name = "metag_da"; + channel_driver->name = "ttyDA"; + channel_driver->major = DA_TTY_MAJOR; + channel_driver->minor_start = 0; + channel_driver->type = TTY_DRIVER_TYPE_SERIAL; + channel_driver->subtype = SERIAL_TYPE_NORMAL; + channel_driver->init_termios = tty_std_termios; + channel_driver->init_termios.c_cflag |= CLOCAL; + + tty_set_operations(channel_driver, &dashtty_ops); + for (nport = 0; nport < NUM_TTY_CHANNELS; nport++) { + dport = &dashtty_ports[nport]; + tty_port_init(&dport->port); + dport->port.ops = &dashtty_port_ops; + spin_lock_init(&dport->rx_lock); + mutex_init(&dport->xmit_lock); + /* the xmit buffer starts empty, i.e. completely written */ + init_completion(&dport->xmit_empty); + complete(&dport->xmit_empty); + } + + setup_timer(&put_timer, dashtty_put_timer, 0); + + init_waitqueue_head(&dashtty_waitqueue); + dashtty_thread = kthread_create(put_data, NULL, "ttyDA"); + if (IS_ERR(dashtty_thread)) { + pr_err("Couldn't create dashtty thread\n"); + ret = PTR_ERR(dashtty_thread); + goto err_destroy_ports; + } + /* + * Bind the writer thread to the boot CPU so it can't migrate. + * DA channels are per-CPU and we want all channel I/O to be on a single + * predictable CPU. + */ + kthread_bind(dashtty_thread, 0); + wake_up_process(dashtty_thread); + + ret = tty_register_driver(channel_driver); + + if (ret < 0) { + pr_err("Couldn't install dashtty driver: err %d\n", + ret); + goto err_stop_kthread; + } + + return 0; + +err_stop_kthread: + kthread_stop(dashtty_thread); +err_destroy_ports: + for (nport = 0; nport < NUM_TTY_CHANNELS; nport++) { + dport = &dashtty_ports[nport]; + tty_port_destroy(&dport->port); + } + put_tty_driver(channel_driver); + return ret; +} + +static void dashtty_exit(void) +{ + int nport; + struct dashtty_port *dport; + + del_timer_sync(&put_timer); + kthread_stop(dashtty_thread); + del_timer_sync(&poll_timer); + tty_unregister_driver(channel_driver); + for (nport = 0; nport < NUM_TTY_CHANNELS; nport++) { + dport = &dashtty_ports[nport]; + tty_port_destroy(&dport->port); + } + put_tty_driver(channel_driver); +} + +module_init(dashtty_init); +module_exit(dashtty_exit); + +#ifdef CONFIG_DA_CONSOLE + +static void dash_console_write(struct console *co, const char *s, + unsigned int count) +{ + int actually_written; + + chancall(WRBUF, CONSOLE_CHANNEL, count, (void *)s, &actually_written); +} + +static struct tty_driver *dash_console_device(struct console *c, int *index) +{ + *index = c->index; + return channel_driver; +} + +struct console dash_console = { + .name = "ttyDA", + .write = dash_console_write, + .device = dash_console_device, + .flags = CON_PRINTBUFFER, + .index = 1, +}; + +#endif |