1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * pmi driver
4 *
5 * (C) Copyright IBM Deutschland Entwicklung GmbH 2005
6 *
7 * PMI (Platform Management Interrupt) is a way to communicate
8 * with the BMC (Baseboard Management Controller) via interrupts.
9 * Unlike IPMI it is bidirectional and has a low latency.
10 *
11 * Author: Christian Krafft <krafft@de.ibm.com>
12 */
13
14#include <linux/interrupt.h>
15#include <linux/slab.h>
16#include <linux/completion.h>
17#include <linux/spinlock.h>
18#include <linux/module.h>
19#include <linux/workqueue.h>
20#include <linux/of_device.h>
21#include <linux/of_platform.h>
22
23#include <asm/io.h>
24#include <asm/pmi.h>
25#include <asm/prom.h>
26
27struct pmi_data {
28	struct list_head	handler;
29	spinlock_t		handler_spinlock;
30	spinlock_t		pmi_spinlock;
31	struct mutex		msg_mutex;
32	pmi_message_t		msg;
33	struct completion	*completion;
34	struct platform_device	*dev;
35	int			irq;
36	u8 __iomem		*pmi_reg;
37	struct work_struct	work;
38};
39
40static struct pmi_data *data;
41
42static irqreturn_t pmi_irq_handler(int irq, void *dev_id)
43{
44	u8 type;
45	int rc;
46
47	spin_lock(&data->pmi_spinlock);
48
49	type = ioread8(data->pmi_reg + PMI_READ_TYPE);
50	pr_debug("pmi: got message of type %d\n", type);
51
52	if (type & PMI_ACK && !data->completion) {
53		printk(KERN_WARNING "pmi: got unexpected ACK message.\n");
54		rc = -EIO;
55		goto unlock;
56	}
57
58	if (data->completion && !(type & PMI_ACK)) {
59		printk(KERN_WARNING "pmi: expected ACK, but got %d\n", type);
60		rc = -EIO;
61		goto unlock;
62	}
63
64	data->msg.type = type;
65	data->msg.data0 = ioread8(data->pmi_reg + PMI_READ_DATA0);
66	data->msg.data1 = ioread8(data->pmi_reg + PMI_READ_DATA1);
67	data->msg.data2 = ioread8(data->pmi_reg + PMI_READ_DATA2);
68	rc = 0;
69unlock:
70	spin_unlock(&data->pmi_spinlock);
71
72	if (rc == -EIO) {
73		rc = IRQ_HANDLED;
74		goto out;
75	}
76
77	if (data->msg.type & PMI_ACK) {
78		complete(data->completion);
79		rc = IRQ_HANDLED;
80		goto out;
81	}
82
83	schedule_work(&data->work);
84
85	rc = IRQ_HANDLED;
86out:
87	return rc;
88}
89
90
91static const struct of_device_id pmi_match[] = {
92	{ .type = "ibm,pmi", .name = "ibm,pmi" },
93	{ .type = "ibm,pmi" },
94	{},
95};
96
97MODULE_DEVICE_TABLE(of, pmi_match);
98
99static void pmi_notify_handlers(struct work_struct *work)
100{
101	struct pmi_handler *handler;
102
103	spin_lock(&data->handler_spinlock);
104	list_for_each_entry(handler, &data->handler, node) {
105		pr_debug("pmi: notifying handler %p\n", handler);
106		if (handler->type == data->msg.type)
107			handler->handle_pmi_message(data->msg);
108	}
109	spin_unlock(&data->handler_spinlock);
110}
111
112static int pmi_of_probe(struct platform_device *dev)
113{
114	struct device_node *np = dev->dev.of_node;
115	int rc;
116
117	if (data) {
118		printk(KERN_ERR "pmi: driver has already been initialized.\n");
119		rc = -EBUSY;
120		goto out;
121	}
122
123	data = kzalloc(sizeof(struct pmi_data), GFP_KERNEL);
124	if (!data) {
125		printk(KERN_ERR "pmi: could not allocate memory.\n");
126		rc = -ENOMEM;
127		goto out;
128	}
129
130	data->pmi_reg = of_iomap(np, 0);
131	if (!data->pmi_reg) {
132		printk(KERN_ERR "pmi: invalid register address.\n");
133		rc = -EFAULT;
134		goto error_cleanup_data;
135	}
136
137	INIT_LIST_HEAD(&data->handler);
138
139	mutex_init(&data->msg_mutex);
140	spin_lock_init(&data->pmi_spinlock);
141	spin_lock_init(&data->handler_spinlock);
142
143	INIT_WORK(&data->work, pmi_notify_handlers);
144
145	data->dev = dev;
146
147	data->irq = irq_of_parse_and_map(np, 0);
148	if (!data->irq) {
149		printk(KERN_ERR "pmi: invalid interrupt.\n");
150		rc = -EFAULT;
151		goto error_cleanup_iomap;
152	}
153
154	rc = request_irq(data->irq, pmi_irq_handler, 0, "pmi", NULL);
155	if (rc) {
156		printk(KERN_ERR "pmi: can't request IRQ %d: returned %d\n",
157				data->irq, rc);
158		goto error_cleanup_iomap;
159	}
160
161	printk(KERN_INFO "pmi: found pmi device at addr %p.\n", data->pmi_reg);
162
163	goto out;
164
165error_cleanup_iomap:
166	iounmap(data->pmi_reg);
167
168error_cleanup_data:
169	kfree(data);
170
171out:
172	return rc;
173}
174
175static int pmi_of_remove(struct platform_device *dev)
176{
177	struct pmi_handler *handler, *tmp;
178
179	free_irq(data->irq, NULL);
180	iounmap(data->pmi_reg);
181
182	spin_lock(&data->handler_spinlock);
183
184	list_for_each_entry_safe(handler, tmp, &data->handler, node)
185		list_del(&handler->node);
186
187	spin_unlock(&data->handler_spinlock);
188
189	kfree(data);
190	data = NULL;
191
192	return 0;
193}
194
195static struct platform_driver pmi_of_platform_driver = {
196	.probe		= pmi_of_probe,
197	.remove		= pmi_of_remove,
198	.driver = {
199		.name = "pmi",
200		.of_match_table = pmi_match,
201	},
202};
203module_platform_driver(pmi_of_platform_driver);
204
205int pmi_send_message(pmi_message_t msg)
206{
207	unsigned long flags;
208	DECLARE_COMPLETION_ONSTACK(completion);
209
210	if (!data)
211		return -ENODEV;
212
213	mutex_lock(&data->msg_mutex);
214
215	data->msg = msg;
216	pr_debug("pmi_send_message: msg is %08x\n", *(u32*)&msg);
217
218	data->completion = &completion;
219
220	spin_lock_irqsave(&data->pmi_spinlock, flags);
221	iowrite8(msg.data0, data->pmi_reg + PMI_WRITE_DATA0);
222	iowrite8(msg.data1, data->pmi_reg + PMI_WRITE_DATA1);
223	iowrite8(msg.data2, data->pmi_reg + PMI_WRITE_DATA2);
224	iowrite8(msg.type, data->pmi_reg + PMI_WRITE_TYPE);
225	spin_unlock_irqrestore(&data->pmi_spinlock, flags);
226
227	pr_debug("pmi_send_message: wait for completion\n");
228
229	wait_for_completion_interruptible_timeout(data->completion,
230						  PMI_TIMEOUT);
231
232	data->completion = NULL;
233
234	mutex_unlock(&data->msg_mutex);
235
236	return 0;
237}
238EXPORT_SYMBOL_GPL(pmi_send_message);
239
240int pmi_register_handler(struct pmi_handler *handler)
241{
242	if (!data)
243		return -ENODEV;
244
245	spin_lock(&data->handler_spinlock);
246	list_add_tail(&handler->node, &data->handler);
247	spin_unlock(&data->handler_spinlock);
248
249	return 0;
250}
251EXPORT_SYMBOL_GPL(pmi_register_handler);
252
253void pmi_unregister_handler(struct pmi_handler *handler)
254{
255	if (!data)
256		return;
257
258	pr_debug("pmi: unregistering handler %p\n", handler);
259
260	spin_lock(&data->handler_spinlock);
261	list_del(&handler->node);
262	spin_unlock(&data->handler_spinlock);
263}
264EXPORT_SYMBOL_GPL(pmi_unregister_handler);
265
266MODULE_LICENSE("GPL");
267MODULE_AUTHOR("Christian Krafft <krafft@de.ibm.com>");
268MODULE_DESCRIPTION("IBM Platform Management Interrupt driver");
269