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c942fddf | 1 | // SPDX-License-Identifier: GPL-2.0-or-later |
b5527a77 JD |
2 | /* |
3 | * i2c-smbus.c - SMBus extensions to the I2C protocol | |
4 | * | |
5 | * Copyright (C) 2008 David Brownell | |
7c81c60f | 6 | * Copyright (C) 2010 Jean Delvare <jdelvare@suse.de> |
b5527a77 JD |
7 | */ |
8 | ||
b5527a77 | 9 | #include <linux/device.h> |
b5527a77 JD |
10 | #include <linux/i2c.h> |
11 | #include <linux/i2c-smbus.h> | |
62c874ab WS |
12 | #include <linux/interrupt.h> |
13 | #include <linux/kernel.h> | |
14 | #include <linux/module.h> | |
69d17246 | 15 | #include <linux/of_irq.h> |
5a0e3ad6 | 16 | #include <linux/slab.h> |
62c874ab | 17 | #include <linux/workqueue.h> |
b5527a77 JD |
18 | |
19 | struct i2c_smbus_alert { | |
b5527a77 JD |
20 | struct work_struct alert; |
21 | struct i2c_client *ara; /* Alert response address */ | |
22 | }; | |
23 | ||
24 | struct alert_data { | |
25 | unsigned short addr; | |
e456cd37 BT |
26 | enum i2c_alert_protocol type; |
27 | unsigned int data; | |
b5527a77 JD |
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; | |
0acc2b32 | 35 | struct i2c_driver *driver; |
b5527a77 JD |
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 | |
0acc2b32 | 44 | * a minimal handler. Lock so the driver won't change. |
b5527a77 | 45 | */ |
f635a1e7 | 46 | device_lock(dev); |
0acc2b32 LPC |
47 | if (client->dev.driver) { |
48 | driver = to_i2c_driver(client->dev.driver); | |
49 | if (driver->alert) | |
e456cd37 | 50 | driver->alert(client, data->type, data->data); |
b5527a77 JD |
51 | else |
52 | dev_warn(&client->dev, "no driver alert()!\n"); | |
53 | } else | |
54 | dev_dbg(&client->dev, "alert with no driver\n"); | |
f635a1e7 | 55 | device_unlock(dev); |
b5527a77 JD |
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 | */ | |
9b9f2b8b | 65 | static irqreturn_t smbus_alert(int irq, void *d) |
b5527a77 | 66 | { |
9b9f2b8b | 67 | struct i2c_smbus_alert *alert = d; |
b5527a77 | 68 | struct i2c_client *ara; |
b5527a77 | 69 | |
b5527a77 JD |
70 | ara = alert->ara; |
71 | ||
72 | for (;;) { | |
73 | s32 status; | |
74 | struct alert_data data; | |
75 | ||
76 | /* | |
77 | * Devices with pending alerts reply in address order, low | |
78 | * to high, because of slave transmit arbitration. After | |
79 | * responding, an SMBus device stops asserting SMBALERT#. | |
80 | * | |
edc9102a | 81 | * Note that SMBus 2.0 reserves 10-bit addresses for future |
b5527a77 JD |
82 | * use. We neither handle them, nor try to use PEC here. |
83 | */ | |
84 | status = i2c_smbus_read_byte(ara); | |
85 | if (status < 0) | |
86 | break; | |
87 | ||
e456cd37 | 88 | data.data = status & 1; |
b5527a77 | 89 | data.addr = status >> 1; |
e456cd37 | 90 | data.type = I2C_PROTOCOL_SMBUS_ALERT; |
b5527a77 | 91 | |
b5527a77 | 92 | dev_dbg(&ara->dev, "SMBALERT# from dev 0x%02x, flag %d\n", |
e456cd37 | 93 | data.addr, data.data); |
b5527a77 JD |
94 | |
95 | /* Notify driver for the device which issued the alert */ | |
96 | device_for_each_child(&ara->adapter->dev, &data, | |
97 | smbus_do_alert); | |
b5527a77 JD |
98 | } |
99 | ||
9b9f2b8b | 100 | return IRQ_HANDLED; |
b5527a77 JD |
101 | } |
102 | ||
9b9f2b8b | 103 | static void smbalert_work(struct work_struct *work) |
b5527a77 | 104 | { |
9b9f2b8b PR |
105 | struct i2c_smbus_alert *alert; |
106 | ||
107 | alert = container_of(work, struct i2c_smbus_alert, alert); | |
b5527a77 | 108 | |
9b9f2b8b | 109 | smbus_alert(0, alert); |
b5527a77 | 110 | |
b5527a77 JD |
111 | } |
112 | ||
113 | /* Setup SMBALERT# infrastructure */ | |
114 | static int smbalert_probe(struct i2c_client *ara, | |
115 | const struct i2c_device_id *id) | |
116 | { | |
6d4028c6 | 117 | struct i2c_smbus_alert_setup *setup = dev_get_platdata(&ara->dev); |
b5527a77 JD |
118 | struct i2c_smbus_alert *alert; |
119 | struct i2c_adapter *adapter = ara->adapter; | |
9b9f2b8b | 120 | int res, irq; |
b5527a77 | 121 | |
71b57845 JL |
122 | alert = devm_kzalloc(&ara->dev, sizeof(struct i2c_smbus_alert), |
123 | GFP_KERNEL); | |
b5527a77 JD |
124 | if (!alert) |
125 | return -ENOMEM; | |
126 | ||
69d17246 PR |
127 | if (setup) { |
128 | irq = setup->irq; | |
129 | } else { | |
130 | irq = of_irq_get_byname(adapter->dev.of_node, "smbus_alert"); | |
131 | if (irq <= 0) | |
132 | return irq; | |
133 | } | |
134 | ||
9b9f2b8b | 135 | INIT_WORK(&alert->alert, smbalert_work); |
b5527a77 JD |
136 | alert->ara = ara; |
137 | ||
9b9f2b8b PR |
138 | if (irq > 0) { |
139 | res = devm_request_threaded_irq(&ara->dev, irq, | |
140 | NULL, smbus_alert, | |
141 | IRQF_SHARED | IRQF_ONESHOT, | |
142 | "smbus_alert", alert); | |
71b57845 | 143 | if (res) |
b5527a77 | 144 | return res; |
b5527a77 JD |
145 | } |
146 | ||
147 | i2c_set_clientdata(ara, alert); | |
9b9f2b8b | 148 | dev_info(&adapter->dev, "supports SMBALERT#\n"); |
b5527a77 JD |
149 | |
150 | return 0; | |
151 | } | |
152 | ||
71b57845 | 153 | /* IRQ and memory resources are managed so they are freed automatically */ |
b5527a77 JD |
154 | static int smbalert_remove(struct i2c_client *ara) |
155 | { | |
156 | struct i2c_smbus_alert *alert = i2c_get_clientdata(ara); | |
157 | ||
158 | cancel_work_sync(&alert->alert); | |
b5527a77 JD |
159 | return 0; |
160 | } | |
161 | ||
162 | static const struct i2c_device_id smbalert_ids[] = { | |
163 | { "smbus_alert", 0 }, | |
164 | { /* LIST END */ } | |
165 | }; | |
166 | MODULE_DEVICE_TABLE(i2c, smbalert_ids); | |
167 | ||
168 | static struct i2c_driver smbalert_driver = { | |
169 | .driver = { | |
170 | .name = "smbus_alert", | |
171 | }, | |
172 | .probe = smbalert_probe, | |
173 | .remove = smbalert_remove, | |
174 | .id_table = smbalert_ids, | |
175 | }; | |
176 | ||
b5527a77 JD |
177 | /** |
178 | * i2c_handle_smbus_alert - Handle an SMBus alert | |
179 | * @ara: the ARA client on the relevant adapter | |
180 | * Context: can't sleep | |
181 | * | |
182 | * Helper function to be called from an I2C bus driver's interrupt | |
183 | * handler. It will schedule the alert work, in turn calling the | |
184 | * corresponding I2C device driver's alert function. | |
185 | * | |
186 | * It is assumed that ara is a valid i2c client previously returned by | |
ed680522 | 187 | * i2c_new_smbus_alert_device(). |
b5527a77 JD |
188 | */ |
189 | int i2c_handle_smbus_alert(struct i2c_client *ara) | |
190 | { | |
191 | struct i2c_smbus_alert *alert = i2c_get_clientdata(ara); | |
192 | ||
193 | return schedule_work(&alert->alert); | |
194 | } | |
195 | EXPORT_SYMBOL_GPL(i2c_handle_smbus_alert); | |
196 | ||
fda2f4af | 197 | module_i2c_driver(smbalert_driver); |
b5527a77 | 198 | |
7c81c60f | 199 | MODULE_AUTHOR("Jean Delvare <jdelvare@suse.de>"); |
b5527a77 JD |
200 | MODULE_DESCRIPTION("SMBus protocol extensions support"); |
201 | MODULE_LICENSE("GPL"); |