diff options
Diffstat (limited to 'drivers/tty/serial/kgdboc.c')
| -rw-r--r-- | drivers/tty/serial/kgdboc.c | 126 |
1 files changed, 101 insertions, 25 deletions
diff --git a/drivers/tty/serial/kgdboc.c b/drivers/tty/serial/kgdboc.c index bfe5e9e034ec..53e7e43cc596 100644 --- a/drivers/tty/serial/kgdboc.c +++ b/drivers/tty/serial/kgdboc.c @@ -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; +static 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) @@ -200,20 +206,79 @@ nmi_con_failed: 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) @@ -236,24 +301,20 @@ 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') @@ -262,8 +323,30 @@ 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; @@ -322,15 +405,8 @@ __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; } @@ -338,7 +414,7 @@ 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"); |