2 files changed, 75 insertions, 0 deletions

diff --git a/Documentation/hwmon/lm90 b/Documentation/hwmon/lm90
index 08106ad7089c..6a03dd4bcc94 100644
--- a/Documentation/hwmon/lm90
+++ b/Documentation/hwmon/lm90
@@ -173,6 +173,18 @@ The lm90 driver will not update its values more frequently than every
 other second; reading them more often will do no harm, but will return
 'old' values.
 
+SMBus Alert Support
+-------------------
+
+This driver has basic support for SMBus alert. When an alert is received,
+the status register is read and the faulty temperature channel is logged.
+
+The Analog Devices chips (ADM1032 and ADT7461) do not implement the SMBus
+alert protocol properly so additional care is needed: the ALERT output is
+disabled when an alert is received, and is re-enabled only when the alarm
+is gone. Otherwise the chip would block alerts from other chips in the bus
+as long as the alarm is active.
+
 PEC Support
 -----------
 
diff --git a/drivers/hwmon/lm90.c b/drivers/hwmon/lm90.c
index 4cbbf1563de6..7cc2708871ab 100644
--- a/drivers/hwmon/lm90.c
+++ b/drivers/hwmon/lm90.c
@@ -152,6 +152,7 @@ static int lm90_detect(struct i2c_client *client, struct i2c_board_info *info);
 static int lm90_probe(struct i2c_client *client,
                       const struct i2c_device_id *id);
 static void lm90_init_client(struct i2c_client *client);
+static void lm90_alert(struct i2c_client *client, unsigned int flag);
 static int lm90_remove(struct i2c_client *client);
 static struct lm90_data *lm90_update_device(struct device *dev);
 
@@ -186,6 +187,7 @@ static struct i2c_driver lm90_driver = {
         },
         .probe          = lm90_probe,
         .remove         = lm90_remove,
+        .alert          = lm90_alert,
         .id_table       = lm90_id,
         .detect         = lm90_detect,
         .address_list   = normal_i2c,
@@ -204,6 +206,7 @@ struct lm90_data {
         int flags;
 
         u8 config_orig;         /* Original configuration register value */
+        u8 alert_alarms;        /* Which alarm bits trigger ALERT# */
 
         /* registers values */
         s8 temp8[4];    /* 0: local low limit
@@ -806,6 +809,19 @@ static int lm90_probe(struct i2c_client *new_client,
                         new_client->flags &= ~I2C_CLIENT_PEC;
         }
 
+        /* Different devices have different alarm bits triggering the
+         * ALERT# output */
+        switch (data->kind) {
+        case lm90:
+        case lm99:
+        case lm86:
+                data->alert_alarms = 0x7b;
+                break;
+        default:
+                data->alert_alarms = 0x7c;
+                break;
+        }
+
         /* Initialize the LM90 chip */
         lm90_init_client(new_client);
 
@@ -895,6 +911,38 @@ static int lm90_remove(struct i2c_client *client)
         return 0;
 }
 
+static void lm90_alert(struct i2c_client *client, unsigned int flag)
+{
+        struct lm90_data *data = i2c_get_clientdata(client);
+        u8 config, alarms;
+
+        lm90_read_reg(client, LM90_REG_R_STATUS, &alarms);
+        if ((alarms & 0x7f) == 0) {
+                dev_info(&client->dev, "Everything OK\n");
+        } else {
+                if (alarms & 0x61)
+                        dev_warn(&client->dev,
+                                 "temp%d out of range, please check!\n", 1);
+                if (alarms & 0x1a)
+                        dev_warn(&client->dev,
+                                 "temp%d out of range, please check!\n", 2);
+                if (alarms & 0x04)
+                        dev_warn(&client->dev,
+                                 "temp%d diode open, please check!\n", 2);
+
+                /* Disable ALERT# output, because these chips don't implement
+                  SMBus alert correctly; they should only hold the alert line
+                  low briefly. */
+                if ((data->kind == adm1032 || data->kind == adt7461)
+                 && (alarms & data->alert_alarms)) {
+                        dev_dbg(&client->dev, "Disabling ALERT#\n");
+                        lm90_read_reg(client, LM90_REG_R_CONFIG1, &config);
+                        i2c_smbus_write_byte_data(client, LM90_REG_W_CONFIG1,
+                                                  config | 0x80);
+                }
+        }
+}
+
 static int lm90_read16(struct i2c_client *client, u8 regh, u8 regl, u16 *value)
 {
         int err;
@@ -982,6 +1030,21 @@ static struct lm90_data *lm90_update_device(struct device *dev)
                 }
                 lm90_read_reg(client, LM90_REG_R_STATUS, &data->alarms);
 
+                /* Re-enable ALERT# output if it was originally enabled and
+                 * relevant alarms are all clear */
+                if ((data->config_orig & 0x80) == 0
+                 && (data->alarms & data->alert_alarms) == 0) {
+                        u8 config;
+
+                        lm90_read_reg(client, LM90_REG_R_CONFIG1, &config);
+                        if (config & 0x80) {
+                                dev_dbg(&client->dev, "Re-enabling ALERT#\n");
+                                i2c_smbus_write_byte_data(client,
+                                                          LM90_REG_W_CONFIG1,
+                                                          config & ~0x80);
+                        }
+                }
+
                 data->last_updated = jiffies;
                 data->valid = 1;
         }