aboutsummaryrefslogtreecommitdiff
path: root/drivers/irqchip/irq-bcm2835.c
blob: 16c78f1c5ef25ad4121b1ee7e2b7fab30cedce95 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
/*
 * Copyright 2010 Broadcom
 * Copyright 2012 Simon Arlott, Chris Boot, Stephen Warren
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * Quirk 1: Shortcut interrupts don't set the bank 1/2 register pending bits
 *
 * If an interrupt fires on bank 1 that isn't in the shortcuts list, bit 8
 * on bank 0 is set to signify that an interrupt in bank 1 has fired, and
 * to look in the bank 1 status register for more information.
 *
 * If an interrupt fires on bank 1 that _is_ in the shortcuts list, its
 * shortcut bit in bank 0 is set as well as its interrupt bit in the bank 1
 * status register, but bank 0 bit 8 is _not_ set.
 *
 * Quirk 2: You can't mask the register 1/2 pending interrupts
 *
 * In a proper cascaded interrupt controller, the interrupt lines with
 * cascaded interrupt controllers on them are just normal interrupt lines.
 * You can mask the interrupts and get on with things. With this controller
 * you can't do that.
 *
 * Quirk 3: The shortcut interrupts can't be (un)masked in bank 0
 *
 * Those interrupts that have shortcuts can only be masked/unmasked in
 * their respective banks' enable/disable registers. Doing so in the bank 0
 * enable/disable registers has no effect.
 *
 * The FIQ control register:
 *  Bits 0-6: IRQ (index in order of interrupts from banks 1, 2, then 0)
 *  Bit    7: Enable FIQ generation
 *  Bits  8+: Unused
 *
 * An interrupt must be disabled before configuring it for FIQ generation
 * otherwise both handlers will fire at the same time!
 */

#include <linux/io.h>
#include <linux/slab.h>
#include <linux/of_address.h>
#include <linux/of_irq.h>
#include <linux/irqdomain.h>
#include <linux/irqchip/bcm2835.h>

#include <asm/exception.h>

/* Put the bank and irq (32 bits) into the hwirq */
#define MAKE_HWIRQ(b, n)	((b << 5) | (n))
#define HWIRQ_BANK(i)		(i >> 5)
#define HWIRQ_BIT(i)		BIT(i & 0x1f)

#define NR_IRQS_BANK0		8
#define BANK0_HWIRQ_MASK	0xff
/* Shortcuts can't be disabled so any unknown new ones need to be masked */
#define SHORTCUT1_MASK		0x00007c00
#define SHORTCUT2_MASK		0x001f8000
#define SHORTCUT_SHIFT		10
#define BANK1_HWIRQ		BIT(8)
#define BANK2_HWIRQ		BIT(9)
#define BANK0_VALID_MASK	(BANK0_HWIRQ_MASK | BANK1_HWIRQ | BANK2_HWIRQ \
					| SHORTCUT1_MASK | SHORTCUT2_MASK)

#define REG_FIQ_CONTROL		0x0c

#define NR_BANKS		3
#define IRQS_PER_BANK		32

static int reg_pending[] __initconst = { 0x00, 0x04, 0x08 };
static int reg_enable[] __initconst = { 0x18, 0x10, 0x14 };
static int reg_disable[] __initconst = { 0x24, 0x1c, 0x20 };
static int bank_irqs[] __initconst = { 8, 32, 32 };

static const int shortcuts[] = {
	7, 9, 10, 18, 19,		/* Bank 1 */
	21, 22, 23, 24, 25, 30		/* Bank 2 */
};

struct armctrl_ic {
	void __iomem *base;
	void __iomem *pending[NR_BANKS];
	void __iomem *enable[NR_BANKS];
	void __iomem *disable[NR_BANKS];
	struct irq_domain *domain;
};

static struct armctrl_ic intc __read_mostly;

static void armctrl_mask_irq(struct irq_data *d)
{
	writel_relaxed(HWIRQ_BIT(d->hwirq), intc.disable[HWIRQ_BANK(d->hwirq)]);
}

static void armctrl_unmask_irq(struct irq_data *d)
{
	writel_relaxed(HWIRQ_BIT(d->hwirq), intc.enable[HWIRQ_BANK(d->hwirq)]);
}

static struct irq_chip armctrl_chip = {
	.name = "ARMCTRL-level",
	.irq_mask = armctrl_mask_irq,
	.irq_unmask = armctrl_unmask_irq
};

static int armctrl_xlate(struct irq_domain *d, struct device_node *ctrlr,
	const u32 *intspec, unsigned int intsize,
	unsigned long *out_hwirq, unsigned int *out_type)
{
	if (WARN_ON(intsize != 2))
		return -EINVAL;

	if (WARN_ON(intspec[0] >= NR_BANKS))
		return -EINVAL;

	if (WARN_ON(intspec[1] >= IRQS_PER_BANK))
		return -EINVAL;

	if (WARN_ON(intspec[0] == 0 && intspec[1] >= NR_IRQS_BANK0))
		return -EINVAL;

	*out_hwirq = MAKE_HWIRQ(intspec[0], intspec[1]);
	*out_type = IRQ_TYPE_NONE;
	return 0;
}

static struct irq_domain_ops armctrl_ops = {
	.xlate = armctrl_xlate
};

static int __init armctrl_of_init(struct device_node *node,
	struct device_node *parent)
{
	void __iomem *base;
	int irq, b, i;

	base = of_iomap(node, 0);
	if (!base)
		panic("%s: unable to map IC registers\n",
			node->full_name);

	intc.domain = irq_domain_add_linear(node, MAKE_HWIRQ(NR_BANKS, 0),
			&armctrl_ops, NULL);
	if (!intc.domain)
		panic("%s: unable to create IRQ domain\n", node->full_name);

	for (b = 0; b < NR_BANKS; b++) {
		intc.pending[b] = base + reg_pending[b];
		intc.enable[b] = base + reg_enable[b];
		intc.disable[b] = base + reg_disable[b];

		for (i = 0; i < bank_irqs[b]; i++) {
			irq = irq_create_mapping(intc.domain, MAKE_HWIRQ(b, i));
			BUG_ON(irq <= 0);
			irq_set_chip_and_handler(irq, &armctrl_chip,
				handle_level_irq);
			set_irq_flags(irq, IRQF_VALID | IRQF_PROBE);
		}
	}
	return 0;
}

static struct of_device_id irq_of_match[] __initconst = {
	{ .compatible = "brcm,bcm2835-armctrl-ic", .data = armctrl_of_init },
	{ }
};

void __init bcm2835_init_irq(void)
{
	of_irq_init(irq_of_match);
}

/*
 * Handle each interrupt across the entire interrupt controller.  This reads the
 * status register before handling each interrupt, which is necessary given that
 * handle_IRQ may briefly re-enable interrupts for soft IRQ handling.
 */

static void armctrl_handle_bank(int bank, struct pt_regs *regs)
{
	u32 stat, irq;

	while ((stat = readl_relaxed(intc.pending[bank]))) {
		irq = MAKE_HWIRQ(bank, ffs(stat) - 1);
		handle_IRQ(irq_linear_revmap(intc.domain, irq), regs);
	}
}

static void armctrl_handle_shortcut(int bank, struct pt_regs *regs,
	u32 stat)
{
	u32 irq = MAKE_HWIRQ(bank, shortcuts[ffs(stat >> SHORTCUT_SHIFT) - 1]);
	handle_IRQ(irq_linear_revmap(intc.domain, irq), regs);
}

asmlinkage void __exception_irq_entry bcm2835_handle_irq(
	struct pt_regs *regs)
{
	u32 stat, irq;

	while ((stat = readl_relaxed(intc.pending[0]) & BANK0_VALID_MASK)) {
		if (stat & BANK0_HWIRQ_MASK) {
			irq = MAKE_HWIRQ(0, ffs(stat & BANK0_HWIRQ_MASK) - 1);
			handle_IRQ(irq_linear_revmap(intc.domain, irq), regs);
		} else if (stat & SHORTCUT1_MASK) {
			armctrl_handle_shortcut(1, regs, stat & SHORTCUT1_MASK);
		} else if (stat & SHORTCUT2_MASK) {
			armctrl_handle_shortcut(2, regs, stat & SHORTCUT2_MASK);
		} else if (stat & BANK1_HWIRQ) {
			armctrl_handle_bank(1, regs);
		} else if (stat & BANK2_HWIRQ) {
			armctrl_handle_bank(2, regs);
		} else {
			BUG();
		}
	}
}