net: dsa: Add support for reporting switch chip temperatures

Some switches provide chip temperature data.
Add support for reporting it through the hwmon subsystem.

Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

3 files changed, 158 insertions, 0 deletions

diff --git a/include/net/dsa.h b/include/net/dsa.h
index b76559293535..55e75e7e8d41 100644
--- a/include/net/dsa.h
+++ b/include/net/dsa.h
@@ -139,6 +139,14 @@ struct dsa_switch {
          */
         struct device           *master_dev;
 
+#ifdef CONFIG_NET_DSA_HWMON
+        /*
+         * Hardware monitoring information
+         */
+        char                    hwmon_name[IFNAMSIZ + 8];
+        struct device           *hwmon_dev;
+#endif
+
         /*
          * Slave mii_bus and devices for the individual ports.
          */
@@ -242,6 +250,14 @@ struct dsa_switch_driver {
                            struct ethtool_eee *e);
         int     (*get_eee)(struct dsa_switch *ds, int port,
                            struct ethtool_eee *e);
+
+#ifdef CONFIG_NET_DSA_HWMON
+        /* Hardware monitoring */
+        int     (*get_temp)(struct dsa_switch *ds, int *temp);
+        int     (*get_temp_limit)(struct dsa_switch *ds, int *temp);
+        int     (*set_temp_limit)(struct dsa_switch *ds, int temp);
+        int     (*get_temp_alarm)(struct dsa_switch *ds, bool *alarm);
+#endif
 };
 
 void register_switch_driver(struct dsa_switch_driver *type);
diff --git a/net/dsa/Kconfig b/net/dsa/Kconfig
index a585fd6352eb..5f8ac404535b 100644
--- a/net/dsa/Kconfig
+++ b/net/dsa/Kconfig
@@ -11,6 +11,17 @@ config NET_DSA
 
 if NET_DSA
 
+config NET_DSA_HWMON
+        bool "Distributed Switch Architecture HWMON support"
+        default y
+        depends on HWMON && !(NET_DSA=y && HWMON=m)
+        ---help---
+          Say Y if you want to expose thermal sensor data on switches supported
+          by the Distributed Switch Architecture.
+
+          Some of those switches contain thermal sensors. This data is available
+          via the hwmon sysfs interface and exposes the onboard sensors.
+
 # tagging formats
 config NET_DSA_TAG_BRCM
         bool
diff --git a/net/dsa/dsa.c b/net/dsa/dsa.c
index 22f34cf4cb27..5edbbca89f1f 100644
--- a/net/dsa/dsa.c
+++ b/net/dsa/dsa.c
@@ -9,6 +9,9 @@
  * (at your option) any later version.
  */
 
+#include <linux/ctype.h>
+#include <linux/device.h>
+#include <linux/hwmon.h>
 #include <linux/list.h>
 #include <linux/platform_device.h>
 #include <linux/slab.h>
@@ -17,6 +20,7 @@
 #include <linux/of.h>
 #include <linux/of_mdio.h>
 #include <linux/of_platform.h>
+#include <linux/sysfs.h>
 #include "dsa_priv.h"
 
 char dsa_driver_version[] = "0.1";
@@ -71,6 +75,104 @@ dsa_switch_probe(struct device *host_dev, int sw_addr, char **_name)
         return ret;
 }
 
+/* hwmon support ************************************************************/
+
+#ifdef CONFIG_NET_DSA_HWMON
+
+static ssize_t temp1_input_show(struct device *dev,
+                                struct device_attribute *attr, char *buf)
+{
+        struct dsa_switch *ds = dev_get_drvdata(dev);
+        int temp, ret;
+
+        ret = ds->drv->get_temp(ds, &temp);
+        if (ret < 0)
+                return ret;
+
+        return sprintf(buf, "%d\n", temp * 1000);
+}
+static DEVICE_ATTR_RO(temp1_input);
+
+static ssize_t temp1_max_show(struct device *dev,
+                              struct device_attribute *attr, char *buf)
+{
+        struct dsa_switch *ds = dev_get_drvdata(dev);
+        int temp, ret;
+
+        ret = ds->drv->get_temp_limit(ds, &temp);
+        if (ret < 0)
+                return ret;
+
+        return sprintf(buf, "%d\n", temp * 1000);
+}
+
+static ssize_t temp1_max_store(struct device *dev,
+                               struct device_attribute *attr, const char *buf,
+                               size_t count)
+{
+        struct dsa_switch *ds = dev_get_drvdata(dev);
+        int temp, ret;
+
+        ret = kstrtoint(buf, 0, &temp);
+        if (ret < 0)
+                return ret;
+
+        ret = ds->drv->set_temp_limit(ds, DIV_ROUND_CLOSEST(temp, 1000));
+        if (ret < 0)
+                return ret;
+
+        return count;
+}
+static DEVICE_ATTR(temp1_max, S_IRUGO, temp1_max_show, temp1_max_store);
+
+static ssize_t temp1_max_alarm_show(struct device *dev,
+                                    struct device_attribute *attr, char *buf)
+{
+        struct dsa_switch *ds = dev_get_drvdata(dev);
+        bool alarm;
+        int ret;
+
+        ret = ds->drv->get_temp_alarm(ds, &alarm);
+        if (ret < 0)
+                return ret;
+
+        return sprintf(buf, "%d\n", alarm);
+}
+static DEVICE_ATTR_RO(temp1_max_alarm);
+
+static struct attribute *dsa_hwmon_attrs[] = {
+        &dev_attr_temp1_input.attr,     /* 0 */
+        &dev_attr_temp1_max.attr,       /* 1 */
+        &dev_attr_temp1_max_alarm.attr, /* 2 */
+        NULL
+};
+
+static umode_t dsa_hwmon_attrs_visible(struct kobject *kobj,
+                                       struct attribute *attr, int index)
+{
+        struct device *dev = container_of(kobj, struct device, kobj);
+        struct dsa_switch *ds = dev_get_drvdata(dev);
+        struct dsa_switch_driver *drv = ds->drv;
+        umode_t mode = attr->mode;
+
+        if (index == 1) {
+                if (!drv->get_temp_limit)
+                        mode = 0;
+                else if (drv->set_temp_limit)
+                        mode |= S_IWUSR;
+        } else if (index == 2 && !drv->get_temp_alarm) {
+                mode = 0;
+        }
+        return mode;
+}
+
+static const struct attribute_group dsa_hwmon_group = {
+        .attrs = dsa_hwmon_attrs,
+        .is_visible = dsa_hwmon_attrs_visible,
+};
+__ATTRIBUTE_GROUPS(dsa_hwmon);
+
+#endif /* CONFIG_NET_DSA_HWMON */
 
 /* basic switch operations **************************************************/
 static struct dsa_switch *
@@ -225,6 +327,31 @@ dsa_switch_setup(struct dsa_switch_tree *dst, int index,
                 ds->ports[i] = slave_dev;
         }
 
+#ifdef CONFIG_NET_DSA_HWMON
+        /* If the switch provides a temperature sensor,
+         * register with hardware monitoring subsystem.
+         * Treat registration error as non-fatal and ignore it.
+         */
+        if (drv->get_temp) {
+                const char *netname = netdev_name(dst->master_netdev);
+                char hname[IFNAMSIZ + 1];
+                int i, j;
+
+                /* Create valid hwmon 'name' attribute */
+                for (i = j = 0; i < IFNAMSIZ && netname[i]; i++) {
+                        if (isalnum(netname[i]))
+                                hname[j++] = netname[i];
+                }
+                hname[j] = '\0';
+                scnprintf(ds->hwmon_name, sizeof(ds->hwmon_name), "%s_dsa%d",
+                          hname, index);
+                ds->hwmon_dev = hwmon_device_register_with_groups(NULL,
+                                        ds->hwmon_name, ds, dsa_hwmon_groups);
+                if (IS_ERR(ds->hwmon_dev))
+                        ds->hwmon_dev = NULL;
+        }
+#endif /* CONFIG_NET_DSA_HWMON */
+
         return ds;
 
 out_free:
@@ -236,6 +363,10 @@ out:
 
 static void dsa_switch_destroy(struct dsa_switch *ds)
 {
+#ifdef CONFIG_NET_DSA_HWMON
+        if (ds->hwmon_dev)
+                hwmon_device_unregister(ds->hwmon_dev);
+#endif
 }
 
 #ifdef CONFIG_PM_SLEEP