1/*
2 * Multiplexed-IRQs driver for TS-4800's FPGA
3 *
4 * Copyright (c) 2015 - Savoir-faire Linux
5 *
6 * This file is licensed under the terms of the GNU General Public
7 * License version 2. This program is licensed "as is" without any
8 * warranty of any kind, whether express or implied.
9 */
10
11#include <linux/interrupt.h>
12#include <linux/io.h>
13#include <linux/irq.h>
14#include <linux/irqchip.h>
15#include <linux/irqchip/chained_irq.h>
16#include <linux/irqdomain.h>
17#include <linux/module.h>
18#include <linux/of.h>
19#include <linux/of_address.h>
20#include <linux/of_irq.h>
21#include <linux/platform_device.h>
22
23#define IRQ_MASK        0x4
24#define IRQ_STATUS      0x8
25
26struct ts4800_irq_data {
27	void __iomem            *base;
28	struct irq_domain       *domain;
29	struct irq_chip         irq_chip;
30};
31
32static void ts4800_irq_mask(struct irq_data *d)
33{
34	struct ts4800_irq_data *data = irq_data_get_irq_chip_data(d);
35	u16 reg = readw(data->base + IRQ_MASK);
36	u16 mask = 1 << d->hwirq;
37
38	writew(reg | mask, data->base + IRQ_MASK);
39}
40
41static void ts4800_irq_unmask(struct irq_data *d)
42{
43	struct ts4800_irq_data *data = irq_data_get_irq_chip_data(d);
44	u16 reg = readw(data->base + IRQ_MASK);
45	u16 mask = 1 << d->hwirq;
46
47	writew(reg & ~mask, data->base + IRQ_MASK);
48}
49
50static int ts4800_irqdomain_map(struct irq_domain *d, unsigned int irq,
51				irq_hw_number_t hwirq)
52{
53	struct ts4800_irq_data *data = d->host_data;
54
55	irq_set_chip_and_handler(irq, &data->irq_chip, handle_simple_irq);
56	irq_set_chip_data(irq, data);
57	irq_set_noprobe(irq);
58
59	return 0;
60}
61
62static const struct irq_domain_ops ts4800_ic_ops = {
63	.map = ts4800_irqdomain_map,
64	.xlate = irq_domain_xlate_onecell,
65};
66
67static void ts4800_ic_chained_handle_irq(struct irq_desc *desc)
68{
69	struct ts4800_irq_data *data = irq_desc_get_handler_data(desc);
70	struct irq_chip *chip = irq_desc_get_chip(desc);
71	u16 status = readw(data->base + IRQ_STATUS);
72
73	chained_irq_enter(chip, desc);
74
75	if (unlikely(status == 0)) {
76		handle_bad_irq(desc);
77		goto out;
78	}
79
80	do {
81		unsigned int bit = __ffs(status);
82		int irq = irq_find_mapping(data->domain, bit);
83
84		status &= ~(1 << bit);
85		generic_handle_irq(irq);
86	} while (status);
87
88out:
89	chained_irq_exit(chip, desc);
90}
91
92static int ts4800_ic_probe(struct platform_device *pdev)
93{
94	struct device_node *node = pdev->dev.of_node;
95	struct ts4800_irq_data *data;
96	struct irq_chip *irq_chip;
97	struct resource *res;
98	int parent_irq;
99
100	data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
101	if (!data)
102		return -ENOMEM;
103
104	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
105	data->base = devm_ioremap_resource(&pdev->dev, res);
106	if (IS_ERR(data->base))
107		return PTR_ERR(data->base);
108
109	writew(0xFFFF, data->base + IRQ_MASK);
110
111	parent_irq = irq_of_parse_and_map(node, 0);
112	if (!parent_irq) {
113		dev_err(&pdev->dev, "failed to get parent IRQ\n");
114		return -EINVAL;
115	}
116
117	irq_chip = &data->irq_chip;
118	irq_chip->name = dev_name(&pdev->dev);
119	irq_chip->irq_mask = ts4800_irq_mask;
120	irq_chip->irq_unmask = ts4800_irq_unmask;
121
122	data->domain = irq_domain_add_linear(node, 8, &ts4800_ic_ops, data);
123	if (!data->domain) {
124		dev_err(&pdev->dev, "cannot add IRQ domain\n");
125		return -ENOMEM;
126	}
127
128	irq_set_chained_handler_and_data(parent_irq,
129					 ts4800_ic_chained_handle_irq, data);
130
131	platform_set_drvdata(pdev, data);
132
133	return 0;
134}
135
136static int ts4800_ic_remove(struct platform_device *pdev)
137{
138	struct ts4800_irq_data *data = platform_get_drvdata(pdev);
139
140	irq_domain_remove(data->domain);
141
142	return 0;
143}
144
145static const struct of_device_id ts4800_ic_of_match[] = {
146	{ .compatible = "technologic,ts4800-irqc", },
147	{},
148};
149MODULE_DEVICE_TABLE(of, ts4800_ic_of_match);
150
151static struct platform_driver ts4800_ic_driver = {
152	.probe  = ts4800_ic_probe,
153	.remove = ts4800_ic_remove,
154	.driver = {
155		.name = "ts4800-irqc",
156		.of_match_table = ts4800_ic_of_match,
157	},
158};
159module_platform_driver(ts4800_ic_driver);
160
161MODULE_AUTHOR("Damien Riegel <damien.riegel@savoirfairelinux.com>");
162MODULE_LICENSE("GPL v2");
163MODULE_ALIAS("platform:ts4800_irqc");
164