1/*
2 * File:	htirq.c
3 * Purpose:	Hypertransport Interrupt Capability
4 *
5 * Copyright (C) 2006 Linux Networx
6 * Copyright (C) Eric Biederman <ebiederman@lnxi.com>
7 */
8
9#include <linux/irq.h>
10#include <linux/pci.h>
11#include <linux/spinlock.h>
12#include <linux/export.h>
13#include <linux/slab.h>
14#include <linux/htirq.h>
15
16/* Global ht irq lock.
17 *
18 * This is needed to serialize access to the data port in hypertransport
19 * irq capability.
20 *
21 * With multiple simultaneous hypertransport irq devices it might pay
22 * to make this more fine grained.  But start with simple, stupid, and correct.
23 */
24static DEFINE_SPINLOCK(ht_irq_lock);
25
26struct ht_irq_cfg {
27	struct pci_dev *dev;
28	 /* Update callback used to cope with buggy hardware */
29	ht_irq_update_t *update;
30	unsigned pos;
31	unsigned idx;
32	struct ht_irq_msg msg;
33};
34
35
36void write_ht_irq_msg(unsigned int irq, struct ht_irq_msg *msg)
37{
38	struct ht_irq_cfg *cfg = irq_get_handler_data(irq);
39	unsigned long flags;
40	spin_lock_irqsave(&ht_irq_lock, flags);
41	if (cfg->msg.address_lo != msg->address_lo) {
42		pci_write_config_byte(cfg->dev, cfg->pos + 2, cfg->idx);
43		pci_write_config_dword(cfg->dev, cfg->pos + 4, msg->address_lo);
44	}
45	if (cfg->msg.address_hi != msg->address_hi) {
46		pci_write_config_byte(cfg->dev, cfg->pos + 2, cfg->idx + 1);
47		pci_write_config_dword(cfg->dev, cfg->pos + 4, msg->address_hi);
48	}
49	if (cfg->update)
50		cfg->update(cfg->dev, irq, msg);
51	spin_unlock_irqrestore(&ht_irq_lock, flags);
52	cfg->msg = *msg;
53}
54
55void fetch_ht_irq_msg(unsigned int irq, struct ht_irq_msg *msg)
56{
57	struct ht_irq_cfg *cfg = irq_get_handler_data(irq);
58	*msg = cfg->msg;
59}
60
61void mask_ht_irq(struct irq_data *data)
62{
63	struct ht_irq_cfg *cfg = irq_data_get_irq_handler_data(data);
64	struct ht_irq_msg msg = cfg->msg;
65
66	msg.address_lo |= 1;
67	write_ht_irq_msg(data->irq, &msg);
68}
69
70void unmask_ht_irq(struct irq_data *data)
71{
72	struct ht_irq_cfg *cfg = irq_data_get_irq_handler_data(data);
73	struct ht_irq_msg msg = cfg->msg;
74
75	msg.address_lo &= ~1;
76	write_ht_irq_msg(data->irq, &msg);
77}
78
79/**
80 * __ht_create_irq - create an irq and attach it to a device.
81 * @dev: The hypertransport device to find the irq capability on.
82 * @idx: Which of the possible irqs to attach to.
83 * @update: Function to be called when changing the htirq message
84 *
85 * The irq number of the new irq or a negative error value is returned.
86 */
87int __ht_create_irq(struct pci_dev *dev, int idx, ht_irq_update_t *update)
88{
89	struct ht_irq_cfg *cfg;
90	int max_irq, pos, irq;
91	unsigned long flags;
92	u32 data;
93
94	pos = pci_find_ht_capability(dev, HT_CAPTYPE_IRQ);
95	if (!pos)
96		return -EINVAL;
97
98	/* Verify the idx I want to use is in range */
99	spin_lock_irqsave(&ht_irq_lock, flags);
100	pci_write_config_byte(dev, pos + 2, 1);
101	pci_read_config_dword(dev, pos + 4, &data);
102	spin_unlock_irqrestore(&ht_irq_lock, flags);
103
104	max_irq = (data >> 16) & 0xff;
105	if (idx > max_irq)
106		return -EINVAL;
107
108	cfg = kmalloc(sizeof(*cfg), GFP_KERNEL);
109	if (!cfg)
110		return -ENOMEM;
111
112	cfg->dev = dev;
113	cfg->update = update;
114	cfg->pos = pos;
115	cfg->idx = 0x10 + (idx * 2);
116	/* Initialize msg to a value that will never match the first write. */
117	cfg->msg.address_lo = 0xffffffff;
118	cfg->msg.address_hi = 0xffffffff;
119
120	irq = irq_alloc_hwirq(dev_to_node(&dev->dev));
121	if (!irq) {
122		kfree(cfg);
123		return -EBUSY;
124	}
125	irq_set_handler_data(irq, cfg);
126
127	if (arch_setup_ht_irq(irq, dev) < 0) {
128		ht_destroy_irq(irq);
129		return -EBUSY;
130	}
131
132	return irq;
133}
134EXPORT_SYMBOL(__ht_create_irq);
135
136/**
137 * ht_create_irq - create an irq and attach it to a device.
138 * @dev: The hypertransport device to find the irq capability on.
139 * @idx: Which of the possible irqs to attach to.
140 *
141 * ht_create_irq needs to be called for all hypertransport devices
142 * that generate irqs.
143 *
144 * The irq number of the new irq or a negative error value is returned.
145 */
146int ht_create_irq(struct pci_dev *dev, int idx)
147{
148	return __ht_create_irq(dev, idx, NULL);
149}
150EXPORT_SYMBOL(ht_create_irq);
151
152/**
153 * ht_destroy_irq - destroy an irq created with ht_create_irq
154 * @irq: irq to be destroyed
155 *
156 * This reverses ht_create_irq removing the specified irq from
157 * existence.  The irq should be free before this happens.
158 */
159void ht_destroy_irq(unsigned int irq)
160{
161	struct ht_irq_cfg *cfg;
162
163	cfg = irq_get_handler_data(irq);
164	irq_set_chip(irq, NULL);
165	irq_set_handler_data(irq, NULL);
166	irq_free_hwirq(irq);
167
168	kfree(cfg);
169}
170EXPORT_SYMBOL(ht_destroy_irq);
171