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 
26 struct ts4800_irq_data {
27 	void __iomem            *base;
28 	struct irq_domain       *domain;
29 	struct irq_chip         irq_chip;
30 };
31 
ts4800_irq_mask(struct irq_data * d)32 static 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 
ts4800_irq_unmask(struct irq_data * d)41 static 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 
ts4800_irqdomain_map(struct irq_domain * d,unsigned int irq,irq_hw_number_t hwirq)50 static 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 
62 static const struct irq_domain_ops ts4800_ic_ops = {
63 	.map = ts4800_irqdomain_map,
64 	.xlate = irq_domain_xlate_onecell,
65 };
66 
ts4800_ic_chained_handle_irq(struct irq_desc * desc)67 static 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 
88 out:
89 	chained_irq_exit(chip, desc);
90 }
91 
ts4800_ic_probe(struct platform_device * pdev)92 static 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 
ts4800_ic_remove(struct platform_device * pdev)136 static 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 
145 static const struct of_device_id ts4800_ic_of_match[] = {
146 	{ .compatible = "technologic,ts4800-irqc", },
147 	{},
148 };
149 MODULE_DEVICE_TABLE(of, ts4800_ic_of_match);
150 
151 static 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 };
159 module_platform_driver(ts4800_ic_driver);
160 
161 MODULE_AUTHOR("Damien Riegel <damien.riegel@savoirfairelinux.com>");
162 MODULE_LICENSE("GPL v2");
163 MODULE_ALIAS("platform:ts4800_irqc");
164