From d562853d3ecc31806412635adcc590b33621b0c0 Mon Sep 17 00:00:00 2001 From: Greg Kroah-Hartman Date: Tue, 26 Jan 2016 15:17:08 -0800 Subject: [PATCH] greybus: svc watchdog: allow it to be enabled/disabled from userspace Sometimes you want to disable the SVC watchdog without having to patch your kernel, so provide a sysfs file to do this. This can let us do power measurements, and let the firmware developers not go crazy worrying that the kernel is going to reset their chips with no notice. Signed-off-by: Greg Kroah-Hartman --- .../greybus/Documentation/sysfs-bus-greybus | 8 +++ drivers/staging/greybus/svc.c | 32 ++++++++++ drivers/staging/greybus/svc.h | 3 + drivers/staging/greybus/svc_watchdog.c | 60 ++++++++++++++++--- 4 files changed, 94 insertions(+), 9 deletions(-) diff --git a/drivers/staging/greybus/Documentation/sysfs-bus-greybus b/drivers/staging/greybus/Documentation/sysfs-bus-greybus index 1550b7f8d776..4493605186b0 100644 --- a/drivers/staging/greybus/Documentation/sysfs-bus-greybus +++ b/drivers/staging/greybus/Documentation/sysfs-bus-greybus @@ -163,3 +163,11 @@ KernelVersion: 4.XX Contact: Greg Kroah-Hartman Description: The version number of the firmware in the SVC device. + +What: /sys/bus/greybus/device/N-svc/watchdog +Date: October 2016 +KernelVersion: 4.XX +Contact: Greg Kroah-Hartman +Description: + If the SVC watchdog is enabled or not. Writing 0 to this + file will disable the watchdog, writing 1 will enable it. diff --git a/drivers/staging/greybus/svc.c b/drivers/staging/greybus/svc.c index b9e5b8565010..eeb251e28441 100644 --- a/drivers/staging/greybus/svc.c +++ b/drivers/staging/greybus/svc.c @@ -70,10 +70,42 @@ static ssize_t intf_eject_store(struct device *dev, } static DEVICE_ATTR_WO(intf_eject); +static ssize_t watchdog_show(struct device *dev, struct device_attribute *attr, + char *buf) +{ + struct gb_svc *svc = to_gb_svc(dev); + + return sprintf(buf, "%s\n", + gb_svc_watchdog_enabled(svc) ? "enabled" : "disabled"); +} + +static ssize_t watchdog_store(struct device *dev, + struct device_attribute *attr, const char *buf, + size_t len) +{ + struct gb_svc *svc = to_gb_svc(dev); + int retval; + bool user_request; + + retval = strtobool(buf, &user_request); + if (retval) + return retval; + + if (user_request) + retval = gb_svc_watchdog_enable(svc); + else + retval = gb_svc_watchdog_disable(svc); + if (retval) + return retval; + return len; +} +static DEVICE_ATTR_RW(watchdog); + static struct attribute *svc_attrs[] = { &dev_attr_endo_id.attr, &dev_attr_ap_intf_id.attr, &dev_attr_intf_eject.attr, + &dev_attr_watchdog.attr, NULL, }; ATTRIBUTE_GROUPS(svc); diff --git a/drivers/staging/greybus/svc.h b/drivers/staging/greybus/svc.h index 0f81e97a2e88..b9fb93ea56be 100644 --- a/drivers/staging/greybus/svc.h +++ b/drivers/staging/greybus/svc.h @@ -61,6 +61,9 @@ int gb_svc_intf_set_power_mode(struct gb_svc *svc, u8 intf_id, u8 hs_series, int gb_svc_ping(struct gb_svc *svc); int gb_svc_watchdog_create(struct gb_svc *svc); void gb_svc_watchdog_destroy(struct gb_svc *svc); +bool gb_svc_watchdog_enabled(struct gb_svc *svc); +int gb_svc_watchdog_enable(struct gb_svc *svc); +int gb_svc_watchdog_disable(struct gb_svc *svc); int gb_svc_protocol_init(void); void gb_svc_protocol_exit(void); diff --git a/drivers/staging/greybus/svc_watchdog.c b/drivers/staging/greybus/svc_watchdog.c index edb73efd53f7..9bd68f4f4cf7 100644 --- a/drivers/staging/greybus/svc_watchdog.c +++ b/drivers/staging/greybus/svc_watchdog.c @@ -15,7 +15,7 @@ struct gb_svc_watchdog { struct delayed_work work; struct gb_svc *svc; - bool finished; + bool enabled; }; static struct delayed_work reset_work; @@ -65,11 +65,16 @@ static void do_work(struct work_struct *work) INIT_DELAYED_WORK(&reset_work, greybus_reset); queue_delayed_work(system_wq, &reset_work, HZ/2); - return; + + /* + * Disable ourselves, we don't want to trip again unless + * userspace wants us to. + */ + watchdog->enabled = false; } /* resubmit our work to happen again, if we are still "alive" */ - if (!watchdog->finished) + if (watchdog->enabled) queue_delayed_work(system_wq, &watchdog->work, SVC_WATCHDOG_PERIOD); } @@ -85,14 +90,12 @@ int gb_svc_watchdog_create(struct gb_svc *svc) if (!watchdog) return -ENOMEM; - watchdog->finished = false; + watchdog->enabled = false; watchdog->svc = svc; INIT_DELAYED_WORK(&watchdog->work, do_work); svc->watchdog = watchdog; - queue_delayed_work(system_wq, &watchdog->work, - SVC_WATCHDOG_PERIOD); - return 0; + return gb_svc_watchdog_enable(svc); } void gb_svc_watchdog_destroy(struct gb_svc *svc) @@ -102,8 +105,47 @@ void gb_svc_watchdog_destroy(struct gb_svc *svc) if (!watchdog) return; - watchdog->finished = true; - cancel_delayed_work_sync(&watchdog->work); + gb_svc_watchdog_disable(svc); svc->watchdog = NULL; kfree(watchdog); } + +bool gb_svc_watchdog_enabled(struct gb_svc *svc) +{ + if (!svc || !svc->watchdog) + return false; + return svc->watchdog->enabled; +} + +int gb_svc_watchdog_enable(struct gb_svc *svc) +{ + struct gb_svc_watchdog *watchdog; + + if (!svc->watchdog) + return -ENODEV; + + watchdog = svc->watchdog; + if (watchdog->enabled) + return 0; + + watchdog->enabled = true; + queue_delayed_work(system_wq, &watchdog->work, + SVC_WATCHDOG_PERIOD); + return 0; +} + +int gb_svc_watchdog_disable(struct gb_svc *svc) +{ + struct gb_svc_watchdog *watchdog; + + if (!svc->watchdog) + return -ENODEV; + + watchdog = svc->watchdog; + if (!watchdog->enabled) + return 0; + + watchdog->enabled = false; + cancel_delayed_work_sync(&watchdog->work); + return 0; +} -- 2.20.1