@@ -20,6 +20,7 @@
#include <linux/vt_kern.h>
#include <linux/input.h>
#include <linux/module.h>
+#include <linux/platform_device.h>
#define MAX_CONFIG_LEN 40
@@ -27,6 +28,7 @@ static struct kgdb_io kgdboc_io_ops;
/* -1 = init not run yet, 0 = unconfigured, 1 = configured. */
static int configured = -1;
+DEFINE_MUTEX(config_mutex);
static char config[MAX_CONFIG_LEN];
static struct kparam_string kps = {
@@ -38,6 +40,8 @@ static int kgdboc_use_kms; /* 1 if we use kernel mode switching */
static struct tty_driver *kgdb_tty_driver;
static int kgdb_tty_line;
+static struct platform_device *kgdboc_pdev;
+
#ifdef CONFIG_KDB_KEYBOARD
static int kgdboc_reset_connect(struct input_handler *handler,
struct input_dev *dev,
@@ -133,11 +137,13 @@ static void kgdboc_unregister_kbd(void)
static void cleanup_kgdboc(void)
{
+ if (configured != 1)
+ return;
+
if (kgdb_unregister_nmi_console())
return;
kgdboc_unregister_kbd();
- if (configured == 1)
- kgdb_unregister_io_module(&kgdboc_io_ops);
+ kgdb_unregister_io_module(&kgdboc_io_ops);
}
static int configure_kgdboc(void)
@@ -198,20 +204,79 @@ static int configure_kgdboc(void)
kgdb_unregister_io_module(&kgdboc_io_ops);
noconfig:
kgdboc_unregister_kbd();
- config[0] = 0;
configured = 0;
- cleanup_kgdboc();
return err;
}
+static int kgdboc_probe(struct platform_device *pdev)
+{
+ int ret = 0;
+
+ mutex_lock(&config_mutex);
+ if (configured != 1) {
+ ret = configure_kgdboc();
+
+ /* Convert "no device" to "defer" so we'll keep trying */
+ if (ret == -ENODEV)
+ ret = -EPROBE_DEFER;
+ }
+ mutex_unlock(&config_mutex);
+
+ return ret;
+}
+
+static struct platform_driver kgdboc_platform_driver = {
+ .probe = kgdboc_probe,
+ .driver = {
+ .name = "kgdboc",
+ .suppress_bind_attrs = true,
+ },
+};
+
static int __init init_kgdboc(void)
{
- /* Already configured? */
- if (configured == 1)
+ int ret;
+
+ /*
+ * kgdboc is a little bit of an odd "platform_driver". It can be
+ * up and running long before the platform_driver object is
+ * created and thus doesn't actually store anything in it. There's
+ * only one instance of kgdb so anything is stored as global state.
+ * The platform_driver is only created so that we can leverage the
+ * kernel's mechanisms (like -EPROBE_DEFER) to call us when our
+ * underlying tty is ready. Here we init our platform driver and
+ * then create the single kgdboc instance.
+ */
+ ret = platform_driver_register(&kgdboc_platform_driver);
+ if (ret)
+ return ret;
+
+ kgdboc_pdev = platform_device_alloc("kgdboc", PLATFORM_DEVID_NONE);
+ if (!kgdboc_pdev) {
+ ret = -ENOMEM;
+ goto err_did_register;
+ }
+
+ ret = platform_device_add(kgdboc_pdev);
+ if (!ret)
return 0;
- return configure_kgdboc();
+ platform_device_put(kgdboc_pdev);
+
+err_did_register:
+ platform_driver_unregister(&kgdboc_platform_driver);
+ return ret;
+}
+
+static void exit_kgdboc(void)
+{
+ mutex_lock(&config_mutex);
+ cleanup_kgdboc();
+ mutex_unlock(&config_mutex);
+
+ platform_device_unregister(kgdboc_pdev);
+ platform_driver_unregister(&kgdboc_platform_driver);
}
static int kgdboc_get_char(void)
@@ -234,24 +299,20 @@ static int param_set_kgdboc_var(const char *kmessage,
const struct kernel_param *kp)
{
size_t len = strlen(kmessage);
+ int ret = 0;
if (len >= MAX_CONFIG_LEN) {
pr_err("config string too long\n");
return -ENOSPC;
}
- /* Only copy in the string if the init function has not run yet */
- if (configured < 0) {
- strcpy(config, kmessage);
- return 0;
- }
-
if (kgdb_connected) {
pr_err("Cannot reconfigure while KGDB is connected.\n");
-
return -EBUSY;
}
+ mutex_lock(&config_mutex);
+
strcpy(config, kmessage);
/* Chop out \n char as a result of echo */
if (len && config[len - 1] == '\n')
@@ -260,8 +321,30 @@ static int param_set_kgdboc_var(const char *kmessage,
if (configured == 1)
cleanup_kgdboc();
- /* Go and configure with the new params. */
- return configure_kgdboc();
+ /*
+ * Configure with the new params as long as init already ran.
+ * Note that we can get called before init if someone loads us
+ * with "modprobe kgdboc kgdboc=..." or if they happen to use the
+ * the odd syntax of "kgdboc.kgdboc=..." on the kernel command.
+ */
+ if (configured >= 0)
+ ret = configure_kgdboc();
+
+ /*
+ * If we couldn't configure then clear out the config. Note that
+ * specifying an invalid config on the kernel command line vs.
+ * through sysfs have slightly different behaviors. If we fail
+ * to configure what was specified on the kernel command line
+ * we'll leave it in the 'config' and return -EPROBE_DEFER from
+ * our probe. When specified through sysfs userspace is
+ * responsible for loading the tty driver before setting up.
+ */
+ if (ret)
+ config[0] = '\0';
+
+ mutex_unlock(&config_mutex);
+
+ return ret;
}
static int dbg_restore_graphics;
@@ -320,15 +403,8 @@ __setup("kgdboc=", kgdboc_option_setup);
/* This is only available if kgdboc is a built in for early debugging */
static int __init kgdboc_early_init(char *opt)
{
- /* save the first character of the config string because the
- * init routine can destroy it.
- */
- char save_ch;
-
kgdboc_option_setup(opt);
- save_ch = config[0];
- init_kgdboc();
- config[0] = save_ch;
+ configure_kgdboc();
return 0;
}
@@ -336,7 +412,7 @@ early_param("ekgdboc", kgdboc_early_init);
#endif /* CONFIG_KGDB_SERIAL_CONSOLE */
module_init(init_kgdboc);
-module_exit(cleanup_kgdboc);
+module_exit(exit_kgdboc);
module_param_call(kgdboc, param_set_kgdboc_var, param_get_string, &kps, 0644);
MODULE_PARM_DESC(kgdboc, "<serial_device>[,baud]");
MODULE_DESCRIPTION("KGDB Console TTY Driver");