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