drivers/i2c/i2c-smbus.c

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This source file includes following definitions.
smbus_do_alert
smbus_alert
smbalert_work
smbalert_probe
smbalert_remove
i2c_handle_smbus_alert
   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * i2c-smbus.c - SMBus extensions to the I2C protocol
   4  *
   5  * Copyright (C) 2008 David Brownell
   6  * Copyright (C) 2010 Jean Delvare <jdelvare@suse.de>
   7  */
   8 
   9 #include <linux/device.h>
  10 #include <linux/i2c.h>
  11 #include <linux/i2c-smbus.h>
  12 #include <linux/interrupt.h>
  13 #include <linux/kernel.h>
  14 #include <linux/module.h>
  15 #include <linux/of_irq.h>
  16 #include <linux/slab.h>
  17 #include <linux/workqueue.h>
  18 
  19 struct i2c_smbus_alert {
  20         struct work_struct      alert;
  21         struct i2c_client       *ara;           /* Alert response address */
  22 };
  23 
  24 struct alert_data {
  25         unsigned short          addr;
  26         enum i2c_alert_protocol type;
  27         unsigned int            data;
  28 };
  29 
  30 /* If this is the alerting device, notify its driver */
  31 static int smbus_do_alert(struct device *dev, void *addrp)
  32 {
  33         struct i2c_client *client = i2c_verify_client(dev);
  34         struct alert_data *data = addrp;
  35         struct i2c_driver *driver;
  36 
  37         if (!client || client->addr != data->addr)
  38                 return 0;
  39         if (client->flags & I2C_CLIENT_TEN)
  40                 return 0;
  41 
  42         /*
  43          * Drivers should either disable alerts, or provide at least
  44          * a minimal handler.  Lock so the driver won't change.
  45          */
  46         device_lock(dev);
  47         if (client->dev.driver) {
  48                 driver = to_i2c_driver(client->dev.driver);
  49                 if (driver->alert)
  50                         driver->alert(client, data->type, data->data);
  51                 else
  52                         dev_warn(&client->dev, "no driver alert()!\n");
  53         } else
  54                 dev_dbg(&client->dev, "alert with no driver\n");
  55         device_unlock(dev);
  56 
  57         /* Stop iterating after we find the device */
  58         return -EBUSY;
  59 }
  60 
  61 /*
  62  * The alert IRQ handler needs to hand work off to a task which can issue
  63  * SMBus calls, because those sleeping calls can't be made in IRQ context.
  64  */
  65 static irqreturn_t smbus_alert(int irq, void *d)
  66 {
  67         struct i2c_smbus_alert *alert = d;
  68         struct i2c_client *ara;
  69         unsigned short prev_addr = 0;   /* Not a valid address */
  70 
  71         ara = alert->ara;
  72 
  73         for (;;) {
  74                 s32 status;
  75                 struct alert_data data;
  76 
  77                 /*
  78                  * Devices with pending alerts reply in address order, low
  79                  * to high, because of slave transmit arbitration.  After
  80                  * responding, an SMBus device stops asserting SMBALERT#.
  81                  *
  82                  * Note that SMBus 2.0 reserves 10-bit addresses for future
  83                  * use.  We neither handle them, nor try to use PEC here.
  84                  */
  85                 status = i2c_smbus_read_byte(ara);
  86                 if (status < 0)
  87                         break;
  88 
  89                 data.data = status & 1;
  90                 data.addr = status >> 1;
  91                 data.type = I2C_PROTOCOL_SMBUS_ALERT;
  92 
  93                 if (data.addr == prev_addr) {
  94                         dev_warn(&ara->dev, "Duplicate SMBALERT# from dev "
  95                                 "0x%02x, skipping\n", data.addr);
  96                         break;
  97                 }
  98                 dev_dbg(&ara->dev, "SMBALERT# from dev 0x%02x, flag %d\n",
  99                         data.addr, data.data);
 100 
 101                 /* Notify driver for the device which issued the alert */
 102                 device_for_each_child(&ara->adapter->dev, &data,
 103                                       smbus_do_alert);
 104                 prev_addr = data.addr;
 105         }
 106 
 107         return IRQ_HANDLED;
 108 }
 109 
 110 static void smbalert_work(struct work_struct *work)
 111 {
 112         struct i2c_smbus_alert *alert;
 113 
 114         alert = container_of(work, struct i2c_smbus_alert, alert);
 115 
 116         smbus_alert(0, alert);
 117 
 118 }
 119 
 120 /* Setup SMBALERT# infrastructure */
 121 static int smbalert_probe(struct i2c_client *ara,
 122                           const struct i2c_device_id *id)
 123 {
 124         struct i2c_smbus_alert_setup *setup = dev_get_platdata(&ara->dev);
 125         struct i2c_smbus_alert *alert;
 126         struct i2c_adapter *adapter = ara->adapter;
 127         int res, irq;
 128 
 129         alert = devm_kzalloc(&ara->dev, sizeof(struct i2c_smbus_alert),
 130                              GFP_KERNEL);
 131         if (!alert)
 132                 return -ENOMEM;
 133 
 134         if (setup) {
 135                 irq = setup->irq;
 136         } else {
 137                 irq = of_irq_get_byname(adapter->dev.of_node, "smbus_alert");
 138                 if (irq <= 0)
 139                         return irq;
 140         }
 141 
 142         INIT_WORK(&alert->alert, smbalert_work);
 143         alert->ara = ara;
 144 
 145         if (irq > 0) {
 146                 res = devm_request_threaded_irq(&ara->dev, irq,
 147                                                 NULL, smbus_alert,
 148                                                 IRQF_SHARED | IRQF_ONESHOT,
 149                                                 "smbus_alert", alert);
 150                 if (res)
 151                         return res;
 152         }
 153 
 154         i2c_set_clientdata(ara, alert);
 155         dev_info(&adapter->dev, "supports SMBALERT#\n");
 156 
 157         return 0;
 158 }
 159 
 160 /* IRQ and memory resources are managed so they are freed automatically */
 161 static int smbalert_remove(struct i2c_client *ara)
 162 {
 163         struct i2c_smbus_alert *alert = i2c_get_clientdata(ara);
 164 
 165         cancel_work_sync(&alert->alert);
 166         return 0;
 167 }
 168 
 169 static const struct i2c_device_id smbalert_ids[] = {
 170         { "smbus_alert", 0 },
 171         { /* LIST END */ }
 172 };
 173 MODULE_DEVICE_TABLE(i2c, smbalert_ids);
 174 
 175 static struct i2c_driver smbalert_driver = {
 176         .driver = {
 177                 .name   = "smbus_alert",
 178         },
 179         .probe          = smbalert_probe,
 180         .remove         = smbalert_remove,
 181         .id_table       = smbalert_ids,
 182 };
 183 
 184 /**
 185  * i2c_handle_smbus_alert - Handle an SMBus alert
 186  * @ara: the ARA client on the relevant adapter
 187  * Context: can't sleep
 188  *
 189  * Helper function to be called from an I2C bus driver's interrupt
 190  * handler. It will schedule the alert work, in turn calling the
 191  * corresponding I2C device driver's alert function.
 192  *
 193  * It is assumed that ara is a valid i2c client previously returned by
 194  * i2c_setup_smbus_alert().
 195  */
 196 int i2c_handle_smbus_alert(struct i2c_client *ara)
 197 {
 198         struct i2c_smbus_alert *alert = i2c_get_clientdata(ara);
 199 
 200         return schedule_work(&alert->alert);
 201 }
 202 EXPORT_SYMBOL_GPL(i2c_handle_smbus_alert);
 203 
 204 module_i2c_driver(smbalert_driver);
 205 
 206 MODULE_AUTHOR("Jean Delvare <jdelvare@suse.de>");
 207 MODULE_DESCRIPTION("SMBus protocol extensions support");
 208 MODULE_LICENSE("GPL");
/* [<][>][^][v][top][bottom][index][help] */
root/drivers/i2c/i2c-smbus.c

DEFINITIONS
