1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  * Copyright (C) 2008 Freescale Semiconductor, Inc. All rights reserved.
4  *
5  * Author: John Rigby, <jrigby@freescale.com>
6  *
7  * Description:
8  * MPC5121ADS CPLD irq handling
9  */
10 
11 #undef DEBUG
12 
13 #include <linux/kernel.h>
14 #include <linux/interrupt.h>
15 #include <linux/irq.h>
16 #include <linux/io.h>
17 #include <asm/prom.h>
18 
19 static struct device_node *cpld_pic_node;
20 static struct irq_domain *cpld_pic_host;
21 
22 /*
23  * Bits to ignore in the misc_status register
24  * 0x10 touch screen pendown is hard routed to irq1
25  * 0x02 pci status is read from pci status register
26  */
27 #define MISC_IGNORE 0x12
28 
29 /*
30  * Nothing to ignore in pci status register
31  */
32 #define PCI_IGNORE 0x00
33 
34 struct cpld_pic {
35 	u8 pci_mask;
36 	u8 pci_status;
37 	u8 route;
38 	u8 misc_mask;
39 	u8 misc_status;
40 	u8 misc_control;
41 };
42 
43 static struct cpld_pic __iomem *cpld_regs;
44 
45 static void __iomem *
46 irq_to_pic_mask(unsigned int irq)
47 {
48 	return irq <= 7 ? &cpld_regs->pci_mask : &cpld_regs->misc_mask;
49 }
50 
51 static unsigned int
52 irq_to_pic_bit(unsigned int irq)
53 {
54 	return 1 << (irq & 0x7);
55 }
56 
57 static void
58 cpld_mask_irq(struct irq_data *d)
59 {
60 	unsigned int cpld_irq = (unsigned int)irqd_to_hwirq(d);
61 	void __iomem *pic_mask = irq_to_pic_mask(cpld_irq);
62 
63 	out_8(pic_mask,
64 	      in_8(pic_mask) | irq_to_pic_bit(cpld_irq));
65 }
66 
67 static void
68 cpld_unmask_irq(struct irq_data *d)
69 {
70 	unsigned int cpld_irq = (unsigned int)irqd_to_hwirq(d);
71 	void __iomem *pic_mask = irq_to_pic_mask(cpld_irq);
72 
73 	out_8(pic_mask,
74 	      in_8(pic_mask) & ~irq_to_pic_bit(cpld_irq));
75 }
76 
77 static struct irq_chip cpld_pic = {
78 	.name = "CPLD PIC",
79 	.irq_mask = cpld_mask_irq,
80 	.irq_ack = cpld_mask_irq,
81 	.irq_unmask = cpld_unmask_irq,
82 };
83 
84 static unsigned int
85 cpld_pic_get_irq(int offset, u8 ignore, u8 __iomem *statusp,
86 			    u8 __iomem *maskp)
87 {
88 	u8 status = in_8(statusp);
89 	u8 mask = in_8(maskp);
90 
91 	/* ignore don't cares and masked irqs */
92 	status |= (ignore | mask);
93 
94 	if (status == 0xff)
95 		return ~0;
96 
97 	return ffz(status) + offset;
98 }
99 
100 static void cpld_pic_cascade(struct irq_desc *desc)
101 {
102 	unsigned int hwirq;
103 
104 	hwirq = cpld_pic_get_irq(0, PCI_IGNORE, &cpld_regs->pci_status,
105 		&cpld_regs->pci_mask);
106 	if (hwirq != ~0) {
107 		generic_handle_domain_irq(cpld_pic_host, hwirq);
108 		return;
109 	}
110 
111 	hwirq = cpld_pic_get_irq(8, MISC_IGNORE, &cpld_regs->misc_status,
112 		&cpld_regs->misc_mask);
113 	if (hwirq != ~0) {
114 		generic_handle_domain_irq(cpld_pic_host, hwirq);
115 		return;
116 	}
117 }
118 
119 static int
120 cpld_pic_host_match(struct irq_domain *h, struct device_node *node,
121 		    enum irq_domain_bus_token bus_token)
122 {
123 	return cpld_pic_node == node;
124 }
125 
126 static int
127 cpld_pic_host_map(struct irq_domain *h, unsigned int virq,
128 			     irq_hw_number_t hw)
129 {
130 	irq_set_status_flags(virq, IRQ_LEVEL);
131 	irq_set_chip_and_handler(virq, &cpld_pic, handle_level_irq);
132 	return 0;
133 }
134 
135 static const struct irq_domain_ops cpld_pic_host_ops = {
136 	.match = cpld_pic_host_match,
137 	.map = cpld_pic_host_map,
138 };
139 
140 void __init
141 mpc5121_ads_cpld_map(void)
142 {
143 	struct device_node *np = NULL;
144 
145 	np = of_find_compatible_node(NULL, NULL, "fsl,mpc5121ads-cpld-pic");
146 	if (!np) {
147 		printk(KERN_ERR "CPLD PIC init: can not find cpld-pic node\n");
148 		return;
149 	}
150 
151 	cpld_regs = of_iomap(np, 0);
152 	of_node_put(np);
153 }
154 
155 void __init
156 mpc5121_ads_cpld_pic_init(void)
157 {
158 	unsigned int cascade_irq;
159 	struct device_node *np = NULL;
160 
161 	pr_debug("cpld_ic_init\n");
162 
163 	np = of_find_compatible_node(NULL, NULL, "fsl,mpc5121ads-cpld-pic");
164 	if (!np) {
165 		printk(KERN_ERR "CPLD PIC init: can not find cpld-pic node\n");
166 		return;
167 	}
168 
169 	if (!cpld_regs)
170 		goto end;
171 
172 	cascade_irq = irq_of_parse_and_map(np, 0);
173 	if (!cascade_irq)
174 		goto end;
175 
176 	/*
177 	 * statically route touch screen pendown through 1
178 	 * and ignore it here
179 	 * route all others through our cascade irq
180 	 */
181 	out_8(&cpld_regs->route, 0xfd);
182 	out_8(&cpld_regs->pci_mask, 0xff);
183 	/* unmask pci ints in misc mask */
184 	out_8(&cpld_regs->misc_mask, ~(MISC_IGNORE));
185 
186 	cpld_pic_node = of_node_get(np);
187 
188 	cpld_pic_host = irq_domain_add_linear(np, 16, &cpld_pic_host_ops, NULL);
189 	if (!cpld_pic_host) {
190 		printk(KERN_ERR "CPLD PIC: failed to allocate irq host!\n");
191 		goto end;
192 	}
193 
194 	irq_set_chained_handler(cascade_irq, cpld_pic_cascade);
195 end:
196 	of_node_put(np);
197 }
198