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-rw-r--r--arch/alpha/kernel/srmcons.c289
1 files changed, 289 insertions, 0 deletions
diff --git a/arch/alpha/kernel/srmcons.c b/arch/alpha/kernel/srmcons.c
new file mode 100644
index 000000000..6dc952b0d
--- /dev/null
+++ b/arch/alpha/kernel/srmcons.c
@@ -0,0 +1,289 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * linux/arch/alpha/kernel/srmcons.c
+ *
+ * Callback based driver for SRM Console console device.
+ * (TTY driver and console driver)
+ */
+
+#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 <linux/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_port port;
+ struct timer_list timer;
+} srmcons_singleton;
+
+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_port *port)
+{
+ srmcons_result result;
+ int count = 0, loops = 0;
+
+ do {
+ result.as_long = callback_getc(0);
+ if (result.bits.status < 2) {
+ tty_insert_flip_char(port, (char)result.bits.c, 0);
+ count++;
+ }
+ } while((result.bits.status & 1) && (++loops < 10));
+
+ if (count)
+ tty_flip_buffer_push(port);
+
+ return count;
+}
+
+static void
+srmcons_receive_chars(struct timer_list *t)
+{
+ struct srmcons_private *srmconsp = from_timer(srmconsp, t, timer);
+ struct tty_port *port = &srmconsp->port;
+ unsigned long flags;
+ int incr = 10;
+
+ local_irq_save(flags);
+ if (spin_trylock(&srmcons_callback_lock)) {
+ if (!srmcons_do_receive_chars(port))
+ incr = 100;
+ spin_unlock(&srmcons_callback_lock);
+ }
+
+ spin_lock(&port->lock);
+ if (port->tty)
+ mod_timer(&srmconsp->timer, jiffies + incr);
+ spin_unlock(&port->lock);
+
+ local_irq_restore(flags);
+}
+
+/* called with callback_lock held */
+static int
+srmcons_do_write(struct tty_port *port, 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 port was provided
+ */
+ if (port)
+ srmcons_do_receive_chars(port);
+ }
+
+ 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->port, (const char *) buf, count);
+ spin_unlock_irqrestore(&srmcons_callback_lock, flags);
+
+ return count;
+}
+
+static unsigned int
+srmcons_write_room(struct tty_struct *tty)
+{
+ return 512;
+}
+
+static int
+srmcons_open(struct tty_struct *tty, struct file *filp)
+{
+ struct srmcons_private *srmconsp = &srmcons_singleton;
+ struct tty_port *port = &srmconsp->port;
+ unsigned long flags;
+
+ spin_lock_irqsave(&port->lock, flags);
+
+ if (!port->tty) {
+ tty->driver_data = srmconsp;
+ tty->port = port;
+ port->tty = tty; /* XXX proper refcounting */
+ mod_timer(&srmconsp->timer, jiffies + 10);
+ }
+
+ spin_unlock_irqrestore(&port->lock, flags);
+
+ return 0;
+}
+
+static void
+srmcons_close(struct tty_struct *tty, struct file *filp)
+{
+ struct srmcons_private *srmconsp = tty->driver_data;
+ struct tty_port *port = &srmconsp->port;
+ unsigned long flags;
+
+ spin_lock_irqsave(&port->lock, flags);
+
+ if (tty->count == 1) {
+ port->tty = NULL;
+ del_timer(&srmconsp->timer);
+ }
+
+ spin_unlock_irqrestore(&port->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,
+};
+
+static int __init
+srmcons_init(void)
+{
+ timer_setup(&srmcons_singleton.timer, srmcons_receive_chars, 0);
+ if (srm_is_registered_console) {
+ struct tty_driver *driver;
+ int err;
+
+ driver = tty_alloc_driver(MAX_SRM_CONSOLE_DEVICES, 0);
+ if (IS_ERR(driver))
+ return PTR_ERR(driver);
+
+ tty_port_init(&srmcons_singleton.port);
+
+ 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);
+ tty_port_link_device(&srmcons_singleton.port, driver, 0);
+ err = tty_register_driver(driver);
+ if (err) {
+ tty_driver_kref_put(driver);
+ tty_port_destroy(&srmcons_singleton.port);
+ return err;
+ }
+ srmcons_driver = driver;
+ }
+
+ return -ENODEV;
+}
+device_initcall(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;
+ }
+}