1 files changed, 326 insertions, 0 deletions

diff --git a/arch/alpha/kernel/srmcons.c b/arch/alpha/kernel/srmcons.c
new file mode 100644
index 000000000000..3b30d4f1fc42
--- /dev/null
+++ b/arch/alpha/kernel/srmcons.c
@@ -0,0 +1,326 @@
+/*
+ *      linux/arch/alpha/kernel/srmcons.c
+ *
+ * Callback based driver for SRM Console console device.
+ * (TTY driver and console driver)
+ */
+
+#include <linux/config.h>
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/console.h>
+#include <linux/delay.h>
+#include <linux/mm.h>
+#include <linux/slab.h>
+#include <linux/spinlock.h>
+#include <linux/timer.h>
+#include <linux/tty.h>
+#include <linux/tty_driver.h>
+#include <linux/tty_flip.h>
+
+#include <asm/console.h>
+#include <asm/uaccess.h>
+
+
+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) {
+                spin_lock_irqsave(&srmconsp_lock, flags);
+
+                srmconsp = kmalloc(sizeof(*srmconsp), GFP_KERNEL);
+                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 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 __init
+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,
+        .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;
+        }
+}