sysfs.c: add alarms attribute within every channel

Alarms are raised by some events and are persistent (in sysfs
and in the control blocks) until they are cleared in sysfs.
Clearing is write-1-to-clear (i.e.: write 32 to clear bit 5).

Signed-off-by: Federico Vaga <federico.vaga@gmail.com>
Acked-by: Alessandro Rubini <rubini@gnudd.com>

sysfs.c

@@ -595,6 +595,44 @@ static ssize_t zobj_show_devname(struct device *dev,
 
 }
 
+/*
+ * zobj_show_alarm
+ * It get alarm status from the current control of the channel and it return
+ * the value to sysfs
+ */
+static ssize_t zio_show_alarm(struct device *dev,
+			       struct device_attribute *attr, char *buf)
+{
+	struct zio_channel *chan = to_zio_chan(dev);
+	struct zio_control *ctrl = chan->current_ctrl;
+
+	return sprintf(buf, "%d\n", (ctrl->zio_alarms << 8) | ctrl->drv_alarms);
+}
+
+/*
+ * zio_store_alarm
+ * It get from the user the alarm to clear, then it clears the alarm in the
+ * curren control of the channel
+ */
+static ssize_t zio_store_alarm(struct device *dev,
+			       struct device_attribute *attr,
+			       const char *buf, size_t count)
+{
+	struct zio_channel *chan = to_zio_chan(dev);
+	struct zio_control *ctrl = chan->current_ctrl;
+	uint16_t clr_alarm;
+	long val;
+
+	if (strict_strtol(buf, 0, &val))
+		return -EINVAL;
+
+	clr_alarm = val;
+	ctrl->zio_alarms &= (~((clr_alarm & 0xFF00) >> 8));
+	ctrl->drv_alarms &= (~(clr_alarm & 0xFF));
+
+	return count;
+}
+
 #if ZIO_HAS_BINARY_CONTROL
 /*
  * zobj_read_cur_ctrl
@@ -639,6 +677,7 @@ enum zio_default_attribute_numeration {
 	ZIO_DAN_DNAM,	/* devname */
 	ZIO_DAN_TYPE,	/* devtype */
 	ZIO_DAN_FLUS,	/* flush */
+	ZIO_DAN_ALAR,	/* alarms */
 };
 
 /* default zio attributes */
@@ -655,6 +694,8 @@ static struct device_attribute zio_default_attributes[] = {
 				zobj_show_devname, NULL),
 	[ZIO_DAN_TYPE] = __ATTR(devtype, ZIO_RO_PERM,
 				zobj_show_dev_type, NULL),
+	[ZIO_DAN_ALAR] = __ATTR(alarms, ZIO_RW_PERM,
+				zio_show_alarm, zio_store_alarm),
 	__ATTR_NULL,
 };
 /* default attributes for most of the zio objects */
@@ -675,6 +716,11 @@ static struct attribute *def_cset_attrs_ptr[] = {
 	&zio_default_attributes[ZIO_DAN_CBUF].attr,
 	NULL,
 };
+/* default attributes for channel */
+static struct attribute *def_chan_attrs_ptr[] = {
+	&zio_default_attributes[ZIO_DAN_ALAR].attr,
+	NULL,
+};
 /* default attributes for buffer instance */
 static struct attribute *def_bi_attrs_ptr[] = {
 	&zio_default_attributes[ZIO_DAN_NAME].attr,
@@ -685,6 +731,7 @@ static struct attribute *def_bi_attrs_ptr[] = {
 enum zio_default_attribute_group_enumeration {
 	ZIO_DAG_ALL = 0,	/* Group valid for any ZIO object*/
 	ZIO_DAG_CSET,	/* Only for cset */
+	ZIO_DAG_CHAN,	/* Only for channel */
 	ZIO_DAG_BI,	/* Only for buffer instance */
 	ZIO_DAG_HIE,	/* Only within device hierarchy (dev, cset, chan) */
 };
@@ -697,6 +744,9 @@ static const struct attribute_group zio_groups[] = {
 	[ZIO_DAG_CSET] = {	/* cset only group */
 		.attrs = def_cset_attrs_ptr,
 	},
+	[ZIO_DAG_CHAN] = {
+		.attrs = def_chan_attrs_ptr,
+	},
 	[ZIO_DAG_BI] = {	/* bi only group */
 		.attrs = def_bi_attrs_ptr,
 	},
@@ -720,13 +770,14 @@ static const struct attribute_group *def_cset_groups_ptr[] = {
 /* default groups for channel */
 static const struct attribute_group *def_chan_groups_ptr[] = {
 	&zio_groups[ZIO_DAG_ALL],
+	&zio_groups[ZIO_DAG_CHAN],
 	&zio_groups[ZIO_DAG_HIE],
 	NULL,
 };
 /* default groups for trigger instance */
 static const struct attribute_group *def_ti_groups_ptr[] = {
 	&zio_groups[ZIO_DAG_ALL],
- 	NULL,
+	NULL,
  };
 /* default groups for buffer instance */
 static const struct attribute_group *def_bi_groups_ptr[] = {