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-rw-r--r--drivers/video/console/dummycon.c146
1 files changed, 146 insertions, 0 deletions
diff --git a/drivers/video/console/dummycon.c b/drivers/video/console/dummycon.c
new file mode 100644
index 0000000000..f1711b2f9f
--- /dev/null
+++ b/drivers/video/console/dummycon.c
@@ -0,0 +1,146 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * linux/drivers/video/dummycon.c -- A dummy console driver
+ *
+ * To be used if there's no other console driver (e.g. for plain VGA text)
+ * available, usually until fbcon takes console over.
+ */
+
+#include <linux/types.h>
+#include <linux/kdev_t.h>
+#include <linux/console.h>
+#include <linux/vt_kern.h>
+#include <linux/screen_info.h>
+#include <linux/init.h>
+#include <linux/module.h>
+
+/*
+ * Dummy console driver
+ */
+
+#if defined(__arm__)
+#define DUMMY_COLUMNS screen_info.orig_video_cols
+#define DUMMY_ROWS screen_info.orig_video_lines
+#else
+/* set by Kconfig. Use 80x25 for 640x480 and 160x64 for 1280x1024 */
+#define DUMMY_COLUMNS CONFIG_DUMMY_CONSOLE_COLUMNS
+#define DUMMY_ROWS CONFIG_DUMMY_CONSOLE_ROWS
+#endif
+
+#ifdef CONFIG_FRAMEBUFFER_CONSOLE_DEFERRED_TAKEOVER
+/* These are both protected by the console_lock */
+static RAW_NOTIFIER_HEAD(dummycon_output_nh);
+static bool dummycon_putc_called;
+
+void dummycon_register_output_notifier(struct notifier_block *nb)
+{
+ WARN_CONSOLE_UNLOCKED();
+
+ raw_notifier_chain_register(&dummycon_output_nh, nb);
+
+ if (dummycon_putc_called)
+ nb->notifier_call(nb, 0, NULL);
+}
+
+void dummycon_unregister_output_notifier(struct notifier_block *nb)
+{
+ WARN_CONSOLE_UNLOCKED();
+
+ raw_notifier_chain_unregister(&dummycon_output_nh, nb);
+}
+
+static void dummycon_putc(struct vc_data *vc, int c, int ypos, int xpos)
+{
+ WARN_CONSOLE_UNLOCKED();
+
+ dummycon_putc_called = true;
+ raw_notifier_call_chain(&dummycon_output_nh, 0, NULL);
+}
+
+static void dummycon_putcs(struct vc_data *vc, const unsigned short *s,
+ int count, int ypos, int xpos)
+{
+ int i;
+
+ if (!dummycon_putc_called) {
+ /* Ignore erases */
+ for (i = 0 ; i < count; i++) {
+ if (s[i] != vc->vc_video_erase_char)
+ break;
+ }
+ if (i == count)
+ return;
+
+ dummycon_putc_called = true;
+ }
+
+ raw_notifier_call_chain(&dummycon_output_nh, 0, NULL);
+}
+
+static int dummycon_blank(struct vc_data *vc, int blank, int mode_switch)
+{
+ /* Redraw, so that we get putc(s) for output done while blanked */
+ return 1;
+}
+#else
+static void dummycon_putc(struct vc_data *vc, int c, int ypos, int xpos) { }
+static void dummycon_putcs(struct vc_data *vc, const unsigned short *s,
+ int count, int ypos, int xpos) { }
+static int dummycon_blank(struct vc_data *vc, int blank, int mode_switch)
+{
+ return 0;
+}
+#endif
+
+static const char *dummycon_startup(void)
+{
+ return "dummy device";
+}
+
+static void dummycon_init(struct vc_data *vc, int init)
+{
+ vc->vc_can_do_color = 1;
+ if (init) {
+ vc->vc_cols = DUMMY_COLUMNS;
+ vc->vc_rows = DUMMY_ROWS;
+ } else
+ vc_resize(vc, DUMMY_COLUMNS, DUMMY_ROWS);
+}
+
+static void dummycon_deinit(struct vc_data *vc) { }
+static void dummycon_clear(struct vc_data *vc, int sy, int sx, int height,
+ int width) { }
+static void dummycon_cursor(struct vc_data *vc, int mode) { }
+
+static bool dummycon_scroll(struct vc_data *vc, unsigned int top,
+ unsigned int bottom, enum con_scroll dir,
+ unsigned int lines)
+{
+ return false;
+}
+
+static int dummycon_switch(struct vc_data *vc)
+{
+ return 0;
+}
+
+/*
+ * The console `switch' structure for the dummy console
+ *
+ * Most of the operations are dummies.
+ */
+
+const struct consw dummy_con = {
+ .owner = THIS_MODULE,
+ .con_startup = dummycon_startup,
+ .con_init = dummycon_init,
+ .con_deinit = dummycon_deinit,
+ .con_clear = dummycon_clear,
+ .con_putc = dummycon_putc,
+ .con_putcs = dummycon_putcs,
+ .con_cursor = dummycon_cursor,
+ .con_scroll = dummycon_scroll,
+ .con_switch = dummycon_switch,
+ .con_blank = dummycon_blank,
+};
+EXPORT_SYMBOL_GPL(dummy_con);