From 849369d6c66d3054688672f97d31fceb8e8230fb Mon Sep 17 00:00:00 2001 From: root Date: Fri, 25 Dec 2015 04:40:36 +0000 Subject: initial_commit --- arch/alpha/kernel/srmcons.c | 325 ++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 325 insertions(+) create mode 100644 arch/alpha/kernel/srmcons.c (limited to 'arch/alpha/kernel/srmcons.c') diff --git a/arch/alpha/kernel/srmcons.c b/arch/alpha/kernel/srmcons.c new file mode 100644 index 00000000..783f4e50 --- /dev/null +++ b/arch/alpha/kernel/srmcons.c @@ -0,0 +1,325 @@ +/* + * linux/arch/alpha/kernel/srmcons.c + * + * Callback based driver for SRM Console console device. + * (TTY driver and console driver) + */ + +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#include +#include + + +static DEFINE_SPINLOCK(srmcons_callback_lock); +static int srm_is_registered_console = 0; + +/* + * The TTY driver + */ +#define MAX_SRM_CONSOLE_DEVICES 1 /* only support 1 console device */ + +struct srmcons_private { + struct tty_struct *tty; + struct timer_list timer; + spinlock_t lock; +}; + +typedef union _srmcons_result { + struct { + unsigned long c :61; + unsigned long status :3; + } bits; + long as_long; +} srmcons_result; + +/* called with callback_lock held */ +static int +srmcons_do_receive_chars(struct tty_struct *tty) +{ + srmcons_result result; + int count = 0, loops = 0; + + do { + result.as_long = callback_getc(0); + if (result.bits.status < 2) { + tty_insert_flip_char(tty, (char)result.bits.c, 0); + count++; + } + } while((result.bits.status & 1) && (++loops < 10)); + + if (count) + tty_schedule_flip(tty); + + return count; +} + +static void +srmcons_receive_chars(unsigned long data) +{ + struct srmcons_private *srmconsp = (struct srmcons_private *)data; + unsigned long flags; + int incr = 10; + + local_irq_save(flags); + if (spin_trylock(&srmcons_callback_lock)) { + if (!srmcons_do_receive_chars(srmconsp->tty)) + incr = 100; + spin_unlock(&srmcons_callback_lock); + } + + spin_lock(&srmconsp->lock); + if (srmconsp->tty) { + srmconsp->timer.expires = jiffies + incr; + add_timer(&srmconsp->timer); + } + spin_unlock(&srmconsp->lock); + + local_irq_restore(flags); +} + +/* called with callback_lock held */ +static int +srmcons_do_write(struct tty_struct *tty, const char *buf, int count) +{ + static char str_cr[1] = "\r"; + long c, remaining = count; + srmcons_result result; + char *cur; + int need_cr; + + for (cur = (char *)buf; remaining > 0; ) { + need_cr = 0; + /* + * Break it up into reasonable size chunks to allow a chance + * for input to get in + */ + for (c = 0; c < min_t(long, 128L, remaining) && !need_cr; c++) + if (cur[c] == '\n') + need_cr = 1; + + while (c > 0) { + result.as_long = callback_puts(0, cur, c); + c -= result.bits.c; + remaining -= result.bits.c; + cur += result.bits.c; + + /* + * Check for pending input iff a tty was provided + */ + if (tty) + srmcons_do_receive_chars(tty); + } + + while (need_cr) { + result.as_long = callback_puts(0, str_cr, 1); + if (result.bits.c > 0) + need_cr = 0; + } + } + return count; +} + +static int +srmcons_write(struct tty_struct *tty, + const unsigned char *buf, int count) +{ + unsigned long flags; + + spin_lock_irqsave(&srmcons_callback_lock, flags); + srmcons_do_write(tty, (const char *) buf, count); + spin_unlock_irqrestore(&srmcons_callback_lock, flags); + + return count; +} + +static int +srmcons_write_room(struct tty_struct *tty) +{ + return 512; +} + +static int +srmcons_chars_in_buffer(struct tty_struct *tty) +{ + return 0; +} + +static int +srmcons_get_private_struct(struct srmcons_private **ps) +{ + static struct srmcons_private *srmconsp = NULL; + static DEFINE_SPINLOCK(srmconsp_lock); + unsigned long flags; + int retval = 0; + + if (srmconsp == NULL) { + srmconsp = kmalloc(sizeof(*srmconsp), GFP_KERNEL); + spin_lock_irqsave(&srmconsp_lock, flags); + + if (srmconsp == NULL) + retval = -ENOMEM; + else { + srmconsp->tty = NULL; + spin_lock_init(&srmconsp->lock); + init_timer(&srmconsp->timer); + } + + spin_unlock_irqrestore(&srmconsp_lock, flags); + } + + *ps = srmconsp; + return retval; +} + +static int +srmcons_open(struct tty_struct *tty, struct file *filp) +{ + struct srmcons_private *srmconsp; + unsigned long flags; + int retval; + + retval = srmcons_get_private_struct(&srmconsp); + if (retval) + return retval; + + spin_lock_irqsave(&srmconsp->lock, flags); + + if (!srmconsp->tty) { + tty->driver_data = srmconsp; + + srmconsp->tty = tty; + srmconsp->timer.function = srmcons_receive_chars; + srmconsp->timer.data = (unsigned long)srmconsp; + srmconsp->timer.expires = jiffies + 10; + add_timer(&srmconsp->timer); + } + + spin_unlock_irqrestore(&srmconsp->lock, flags); + + return 0; +} + +static void +srmcons_close(struct tty_struct *tty, struct file *filp) +{ + struct srmcons_private *srmconsp = tty->driver_data; + unsigned long flags; + + spin_lock_irqsave(&srmconsp->lock, flags); + + if (tty->count == 1) { + srmconsp->tty = NULL; + del_timer(&srmconsp->timer); + } + + spin_unlock_irqrestore(&srmconsp->lock, flags); +} + + +static struct tty_driver *srmcons_driver; + +static const struct tty_operations srmcons_ops = { + .open = srmcons_open, + .close = srmcons_close, + .write = srmcons_write, + .write_room = srmcons_write_room, + .chars_in_buffer= srmcons_chars_in_buffer, +}; + +static int __init +srmcons_init(void) +{ + if (srm_is_registered_console) { + struct tty_driver *driver; + int err; + + driver = alloc_tty_driver(MAX_SRM_CONSOLE_DEVICES); + if (!driver) + return -ENOMEM; + driver->driver_name = "srm"; + driver->name = "srm"; + driver->major = 0; /* dynamic */ + driver->minor_start = 0; + driver->type = TTY_DRIVER_TYPE_SYSTEM; + driver->subtype = SYSTEM_TYPE_SYSCONS; + driver->init_termios = tty_std_termios; + tty_set_operations(driver, &srmcons_ops); + err = tty_register_driver(driver); + if (err) { + put_tty_driver(driver); + return err; + } + srmcons_driver = driver; + } + + return -ENODEV; +} + +module_init(srmcons_init); + + +/* + * The console driver + */ +static void +srm_console_write(struct console *co, const char *s, unsigned count) +{ + unsigned long flags; + + spin_lock_irqsave(&srmcons_callback_lock, flags); + srmcons_do_write(NULL, s, count); + spin_unlock_irqrestore(&srmcons_callback_lock, flags); +} + +static struct tty_driver * +srm_console_device(struct console *co, int *index) +{ + *index = co->index; + return srmcons_driver; +} + +static int +srm_console_setup(struct console *co, char *options) +{ + return 0; +} + +static struct console srmcons = { + .name = "srm", + .write = srm_console_write, + .device = srm_console_device, + .setup = srm_console_setup, + .flags = CON_PRINTBUFFER | CON_BOOT, + .index = -1, +}; + +void __init +register_srm_console(void) +{ + if (!srm_is_registered_console) { + callback_open_console(); + register_console(&srmcons); + srm_is_registered_console = 1; + } +} + +void __init +unregister_srm_console(void) +{ + if (srm_is_registered_console) { + callback_close_console(); + unregister_console(&srmcons); + srm_is_registered_console = 0; + } +} -- cgit v1.2.3