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");