Add the rt linux 4.1.3-rt3 as base

[kvmfornfv.git] / kernel / drivers / tty / hvc / hvc_dcc.c

diff --git a/kernel/drivers/tty/hvc/hvc_dcc.c b/kernel/drivers/tty/hvc/hvc_dcc.c
new file mode 100644 (file)
index 0000000..809920d
--- /dev/null
+++ b/kernel/drivers/tty/hvc/hvc_dcc.c
@@ -0,0 +1,89 @@
+/* Copyright (c) 2010, 2014 The Linux Foundation. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 and
+ * only version 2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#include <linux/init.h>
+
+#include <asm/dcc.h>
+#include <asm/processor.h>
+
+#include "hvc_console.h"
+
+/* DCC Status Bits */
+#define DCC_STATUS_RX          (1 << 30)
+#define DCC_STATUS_TX          (1 << 29)
+
+static int hvc_dcc_put_chars(uint32_t vt, const char *buf, int count)
+{
+       int i;
+
+       for (i = 0; i < count; i++) {
+               while (__dcc_getstatus() & DCC_STATUS_TX)
+                       cpu_relax();
+
+               __dcc_putchar(buf[i]);
+       }
+
+       return count;
+}
+
+static int hvc_dcc_get_chars(uint32_t vt, char *buf, int count)
+{
+       int i;
+
+       for (i = 0; i < count; ++i)
+               if (__dcc_getstatus() & DCC_STATUS_RX)
+                       buf[i] = __dcc_getchar();
+               else
+                       break;
+
+       return i;
+}
+
+static bool hvc_dcc_check(void)
+{
+       unsigned long time = jiffies + (HZ / 10);
+
+       /* Write a test character to check if it is handled */
+       __dcc_putchar('\n');
+
+       while (time_is_after_jiffies(time)) {
+               if (!(__dcc_getstatus() & DCC_STATUS_TX))
+                       return true;
+       }
+
+       return false;
+}
+
+static const struct hv_ops hvc_dcc_get_put_ops = {
+       .get_chars = hvc_dcc_get_chars,
+       .put_chars = hvc_dcc_put_chars,
+};
+
+static int __init hvc_dcc_console_init(void)
+{
+       if (!hvc_dcc_check())
+               return -ENODEV;
+
+       hvc_instantiate(0, 0, &hvc_dcc_get_put_ops);
+       return 0;
+}
+console_initcall(hvc_dcc_console_init);
+
+static int __init hvc_dcc_init(void)
+{
+       if (!hvc_dcc_check())
+               return -ENODEV;
+
+       hvc_alloc(0, 0, &hvc_dcc_get_put_ops, 128);
+       return 0;
+}
+device_initcall(hvc_dcc_init);