1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  *  Support for Versatile FPGA-based IRQ controllers
4  */
5 #include <linux/bitops.h>
6 #include <linux/irq.h>
7 #include <linux/io.h>
8 #include <linux/irqchip.h>
9 #include <linux/irqchip/chained_irq.h>
10 #include <linux/irqdomain.h>
11 #include <linux/module.h>
12 #include <linux/of.h>
13 #include <linux/of_address.h>
14 #include <linux/of_irq.h>
15 #include <linux/seq_file.h>
16 
17 #include <asm/exception.h>
18 #include <asm/mach/irq.h>
19 
20 #define IRQ_STATUS		0x00
21 #define IRQ_RAW_STATUS		0x04
22 #define IRQ_ENABLE_SET		0x08
23 #define IRQ_ENABLE_CLEAR	0x0c
24 #define INT_SOFT_SET		0x10
25 #define INT_SOFT_CLEAR		0x14
26 #define FIQ_STATUS		0x20
27 #define FIQ_RAW_STATUS		0x24
28 #define FIQ_ENABLE		0x28
29 #define FIQ_ENABLE_SET		0x28
30 #define FIQ_ENABLE_CLEAR	0x2C
31 
32 #define PIC_ENABLES             0x20	/* set interrupt pass through bits */
33 
34 /**
35  * struct fpga_irq_data - irq data container for the FPGA IRQ controller
36  * @base: memory offset in virtual memory
37  * @domain: IRQ domain for this instance
38  * @valid: mask for valid IRQs on this controller
39  * @used_irqs: number of active IRQs on this controller
40  */
41 struct fpga_irq_data {
42 	void __iomem *base;
43 	u32 valid;
44 	struct irq_domain *domain;
45 	u8 used_irqs;
46 };
47 
48 /* we cannot allocate memory when the controllers are initially registered */
49 static struct fpga_irq_data fpga_irq_devices[CONFIG_VERSATILE_FPGA_IRQ_NR];
50 static int fpga_irq_id;
51 
fpga_irq_mask(struct irq_data * d)52 static void fpga_irq_mask(struct irq_data *d)
53 {
54 	struct fpga_irq_data *f = irq_data_get_irq_chip_data(d);
55 	u32 mask = 1 << d->hwirq;
56 
57 	writel(mask, f->base + IRQ_ENABLE_CLEAR);
58 }
59 
fpga_irq_unmask(struct irq_data * d)60 static void fpga_irq_unmask(struct irq_data *d)
61 {
62 	struct fpga_irq_data *f = irq_data_get_irq_chip_data(d);
63 	u32 mask = 1 << d->hwirq;
64 
65 	writel(mask, f->base + IRQ_ENABLE_SET);
66 }
67 
fpga_irq_print_chip(struct irq_data * d,struct seq_file * p)68 static void fpga_irq_print_chip(struct irq_data *d, struct seq_file *p)
69 {
70 	struct fpga_irq_data *f = irq_data_get_irq_chip_data(d);
71 
72 	seq_printf(p, irq_domain_get_of_node(f->domain)->name);
73 }
74 
75 static const struct irq_chip fpga_chip = {
76 	.irq_ack	= fpga_irq_mask,
77 	.irq_mask	= fpga_irq_mask,
78 	.irq_unmask	= fpga_irq_unmask,
79 	.irq_print_chip	= fpga_irq_print_chip,
80 };
81 
fpga_irq_handle(struct irq_desc * desc)82 static void fpga_irq_handle(struct irq_desc *desc)
83 {
84 	struct irq_chip *chip = irq_desc_get_chip(desc);
85 	struct fpga_irq_data *f = irq_desc_get_handler_data(desc);
86 	u32 status;
87 
88 	chained_irq_enter(chip, desc);
89 
90 	status = readl(f->base + IRQ_STATUS);
91 	if (status == 0) {
92 		do_bad_IRQ(desc);
93 		goto out;
94 	}
95 
96 	do {
97 		unsigned int irq = ffs(status) - 1;
98 
99 		status &= ~(1 << irq);
100 		generic_handle_domain_irq(f->domain, irq);
101 	} while (status);
102 
103 out:
104 	chained_irq_exit(chip, desc);
105 }
106 
107 /*
108  * Handle each interrupt in a single FPGA IRQ controller.  Returns non-zero
109  * if we've handled at least one interrupt.  This does a single read of the
110  * status register and handles all interrupts in order from LSB first.
111  */
handle_one_fpga(struct fpga_irq_data * f,struct pt_regs * regs)112 static int handle_one_fpga(struct fpga_irq_data *f, struct pt_regs *regs)
113 {
114 	int handled = 0;
115 	int irq;
116 	u32 status;
117 
118 	while ((status  = readl(f->base + IRQ_STATUS))) {
119 		irq = ffs(status) - 1;
120 		generic_handle_domain_irq(f->domain, irq);
121 		handled = 1;
122 	}
123 
124 	return handled;
125 }
126 
127 /*
128  * Keep iterating over all registered FPGA IRQ controllers until there are
129  * no pending interrupts.
130  */
fpga_handle_irq(struct pt_regs * regs)131 static asmlinkage void __exception_irq_entry fpga_handle_irq(struct pt_regs *regs)
132 {
133 	int i, handled;
134 
135 	do {
136 		for (i = 0, handled = 0; i < fpga_irq_id; ++i)
137 			handled |= handle_one_fpga(&fpga_irq_devices[i], regs);
138 	} while (handled);
139 }
140 
fpga_irqdomain_map(struct irq_domain * d,unsigned int irq,irq_hw_number_t hwirq)141 static int fpga_irqdomain_map(struct irq_domain *d, unsigned int irq,
142 		irq_hw_number_t hwirq)
143 {
144 	struct fpga_irq_data *f = d->host_data;
145 
146 	/* Skip invalid IRQs, only register handlers for the real ones */
147 	if (!(f->valid & BIT(hwirq)))
148 		return -EPERM;
149 	irq_set_chip_data(irq, f);
150 	irq_set_chip_and_handler(irq, &fpga_chip, handle_level_irq);
151 	irq_set_probe(irq);
152 	return 0;
153 }
154 
155 static const struct irq_domain_ops fpga_irqdomain_ops = {
156 	.map = fpga_irqdomain_map,
157 	.xlate = irq_domain_xlate_onetwocell,
158 };
159 
fpga_irq_init(void __iomem * base,int parent_irq,u32 valid,struct device_node * node)160 static void __init fpga_irq_init(void __iomem *base, int parent_irq,
161 				 u32 valid, struct device_node *node)
162 {
163 	struct fpga_irq_data *f;
164 	int i;
165 
166 	if (fpga_irq_id >= ARRAY_SIZE(fpga_irq_devices)) {
167 		pr_err("%s: too few FPGA IRQ controllers, increase CONFIG_VERSATILE_FPGA_IRQ_NR\n", __func__);
168 		return;
169 	}
170 	f = &fpga_irq_devices[fpga_irq_id];
171 	f->base = base;
172 	f->valid = valid;
173 
174 	if (parent_irq != -1) {
175 		irq_set_chained_handler_and_data(parent_irq, fpga_irq_handle,
176 						 f);
177 	}
178 
179 	f->domain = irq_domain_add_linear(node, fls(valid),
180 					  &fpga_irqdomain_ops, f);
181 
182 	/* This will allocate all valid descriptors in the linear case */
183 	for (i = 0; i < fls(valid); i++)
184 		if (valid & BIT(i)) {
185 			/* Is this still required? */
186 			irq_create_mapping(f->domain, i);
187 			f->used_irqs++;
188 		}
189 
190 	pr_info("FPGA IRQ chip %d \"%s\" @ %p, %u irqs",
191 		fpga_irq_id, node->name, base, f->used_irqs);
192 	if (parent_irq != -1)
193 		pr_cont(", parent IRQ: %d\n", parent_irq);
194 	else
195 		pr_cont("\n");
196 
197 	fpga_irq_id++;
198 }
199 
200 #ifdef CONFIG_OF
fpga_irq_of_init(struct device_node * node,struct device_node * parent)201 static int __init fpga_irq_of_init(struct device_node *node,
202 				   struct device_node *parent)
203 {
204 	void __iomem *base;
205 	u32 clear_mask;
206 	u32 valid_mask;
207 	int parent_irq;
208 
209 	if (WARN_ON(!node))
210 		return -ENODEV;
211 
212 	base = of_iomap(node, 0);
213 	WARN(!base, "unable to map fpga irq registers\n");
214 
215 	if (of_property_read_u32(node, "clear-mask", &clear_mask))
216 		clear_mask = 0;
217 
218 	if (of_property_read_u32(node, "valid-mask", &valid_mask))
219 		valid_mask = 0;
220 
221 	writel(clear_mask, base + IRQ_ENABLE_CLEAR);
222 	writel(clear_mask, base + FIQ_ENABLE_CLEAR);
223 
224 	/* Some chips are cascaded from a parent IRQ */
225 	parent_irq = irq_of_parse_and_map(node, 0);
226 	if (!parent_irq) {
227 		set_handle_irq(fpga_handle_irq);
228 		parent_irq = -1;
229 	}
230 
231 	fpga_irq_init(base, parent_irq, valid_mask, node);
232 
233 	/*
234 	 * On Versatile AB/PB, some secondary interrupts have a direct
235 	 * pass-thru to the primary controller for IRQs 20 and 22-31 which need
236 	 * to be enabled. See section 3.10 of the Versatile AB user guide.
237 	 */
238 	if (of_device_is_compatible(node, "arm,versatile-sic"))
239 		writel(0xffd00000, base + PIC_ENABLES);
240 
241 	return 0;
242 }
243 IRQCHIP_DECLARE(arm_fpga, "arm,versatile-fpga-irq", fpga_irq_of_init);
244 IRQCHIP_DECLARE(arm_fpga_sic, "arm,versatile-sic", fpga_irq_of_init);
245 #endif
246