1 /*
2 * Interrupt handling for GE FPGA based PIC
3 *
4 * Author: Martyn Welch <martyn.welch@ge.com>
5 *
6 * 2008 (c) GE Intelligent Platforms Embedded Systems, Inc.
7 *
8 * This file is licensed under the terms of the GNU General Public License
9 * version 2. This program is licensed "as is" without any warranty of any
10 * kind, whether express or implied.
11 */
12
13 #include <linux/stddef.h>
14 #include <linux/kernel.h>
15 #include <linux/init.h>
16 #include <linux/irq.h>
17 #include <linux/irqdomain.h>
18 #include <linux/interrupt.h>
19 #include <linux/of_address.h>
20 #include <linux/of_irq.h>
21 #include <linux/spinlock.h>
22
23 #include <asm/byteorder.h>
24 #include <asm/io.h>
25 #include <asm/irq.h>
26
27 #include "ge_pic.h"
28
29 #define DEBUG
30 #undef DEBUG
31
32 #ifdef DEBUG
33 #define DBG(fmt...) do { printk(KERN_DEBUG "gef_pic: " fmt); } while (0)
34 #else
35 #define DBG(fmt...) do { } while (0)
36 #endif
37
38 #define GEF_PIC_NUM_IRQS 32
39
40 /* Interrupt Controller Interface Registers */
41 #define GEF_PIC_INTR_STATUS 0x0000
42
43 #define GEF_PIC_INTR_MASK(cpu) (0x0010 + (0x4 * cpu))
44 #define GEF_PIC_CPU0_INTR_MASK GEF_PIC_INTR_MASK(0)
45 #define GEF_PIC_CPU1_INTR_MASK GEF_PIC_INTR_MASK(1)
46
47 #define GEF_PIC_MCP_MASK(cpu) (0x0018 + (0x4 * cpu))
48 #define GEF_PIC_CPU0_MCP_MASK GEF_PIC_MCP_MASK(0)
49 #define GEF_PIC_CPU1_MCP_MASK GEF_PIC_MCP_MASK(1)
50
51
52 static DEFINE_RAW_SPINLOCK(gef_pic_lock);
53
54 static void __iomem *gef_pic_irq_reg_base;
55 static struct irq_domain *gef_pic_irq_host;
56 static int gef_pic_cascade_irq;
57
58 /*
59 * Interrupt Controller Handling
60 *
61 * The interrupt controller handles interrupts for most on board interrupts,
62 * apart from PCI interrupts. For example on SBC610:
63 *
64 * 17:31 RO Reserved
65 * 16 RO PCI Express Doorbell 3 Status
66 * 15 RO PCI Express Doorbell 2 Status
67 * 14 RO PCI Express Doorbell 1 Status
68 * 13 RO PCI Express Doorbell 0 Status
69 * 12 RO Real Time Clock Interrupt Status
70 * 11 RO Temperature Interrupt Status
71 * 10 RO Temperature Critical Interrupt Status
72 * 9 RO Ethernet PHY1 Interrupt Status
73 * 8 RO Ethernet PHY3 Interrupt Status
74 * 7 RO PEX8548 Interrupt Status
75 * 6 RO Reserved
76 * 5 RO Watchdog 0 Interrupt Status
77 * 4 RO Watchdog 1 Interrupt Status
78 * 3 RO AXIS Message FIFO A Interrupt Status
79 * 2 RO AXIS Message FIFO B Interrupt Status
80 * 1 RO AXIS Message FIFO C Interrupt Status
81 * 0 RO AXIS Message FIFO D Interrupt Status
82 *
83 * Interrupts can be forwarded to one of two output lines. Nothing
84 * clever is done, so if the masks are incorrectly set, a single input
85 * interrupt could generate interrupts on both output lines!
86 *
87 * The dual lines are there to allow the chained interrupts to be easily
88 * passed into two different cores. We currently do not use this functionality
89 * in this driver.
90 *
91 * Controller can also be configured to generate Machine checks (MCP), again on
92 * two lines, to be attached to two different cores. It is suggested that these
93 * should be masked out.
94 */
95
gef_pic_cascade(struct irq_desc * desc)96 static void gef_pic_cascade(struct irq_desc *desc)
97 {
98 struct irq_chip *chip = irq_desc_get_chip(desc);
99 unsigned int cascade_irq;
100
101 /*
102 * See if we actually have an interrupt, call generic handling code if
103 * we do.
104 */
105 cascade_irq = gef_pic_get_irq();
106
107 if (cascade_irq)
108 generic_handle_irq(cascade_irq);
109
110 chip->irq_eoi(&desc->irq_data);
111 }
112
gef_pic_mask(struct irq_data * d)113 static void gef_pic_mask(struct irq_data *d)
114 {
115 unsigned long flags;
116 unsigned int hwirq = irqd_to_hwirq(d);
117 u32 mask;
118
119 raw_spin_lock_irqsave(&gef_pic_lock, flags);
120 mask = in_be32(gef_pic_irq_reg_base + GEF_PIC_INTR_MASK(0));
121 mask &= ~(1 << hwirq);
122 out_be32(gef_pic_irq_reg_base + GEF_PIC_INTR_MASK(0), mask);
123 raw_spin_unlock_irqrestore(&gef_pic_lock, flags);
124 }
125
gef_pic_mask_ack(struct irq_data * d)126 static void gef_pic_mask_ack(struct irq_data *d)
127 {
128 /* Don't think we actually have to do anything to ack an interrupt,
129 * we just need to clear down the devices interrupt and it will go away
130 */
131 gef_pic_mask(d);
132 }
133
gef_pic_unmask(struct irq_data * d)134 static void gef_pic_unmask(struct irq_data *d)
135 {
136 unsigned long flags;
137 unsigned int hwirq = irqd_to_hwirq(d);
138 u32 mask;
139
140 raw_spin_lock_irqsave(&gef_pic_lock, flags);
141 mask = in_be32(gef_pic_irq_reg_base + GEF_PIC_INTR_MASK(0));
142 mask |= (1 << hwirq);
143 out_be32(gef_pic_irq_reg_base + GEF_PIC_INTR_MASK(0), mask);
144 raw_spin_unlock_irqrestore(&gef_pic_lock, flags);
145 }
146
147 static struct irq_chip gef_pic_chip = {
148 .name = "gefp",
149 .irq_mask = gef_pic_mask,
150 .irq_mask_ack = gef_pic_mask_ack,
151 .irq_unmask = gef_pic_unmask,
152 };
153
154
155 /* When an interrupt is being configured, this call allows some flexibility
156 * in deciding which irq_chip structure is used
157 */
gef_pic_host_map(struct irq_domain * h,unsigned int virq,irq_hw_number_t hwirq)158 static int gef_pic_host_map(struct irq_domain *h, unsigned int virq,
159 irq_hw_number_t hwirq)
160 {
161 /* All interrupts are LEVEL sensitive */
162 irq_set_status_flags(virq, IRQ_LEVEL);
163 irq_set_chip_and_handler(virq, &gef_pic_chip, handle_level_irq);
164
165 return 0;
166 }
167
gef_pic_host_xlate(struct irq_domain * h,struct device_node * ct,const u32 * intspec,unsigned int intsize,irq_hw_number_t * out_hwirq,unsigned int * out_flags)168 static int gef_pic_host_xlate(struct irq_domain *h, struct device_node *ct,
169 const u32 *intspec, unsigned int intsize,
170 irq_hw_number_t *out_hwirq, unsigned int *out_flags)
171 {
172
173 *out_hwirq = intspec[0];
174 if (intsize > 1)
175 *out_flags = intspec[1];
176 else
177 *out_flags = IRQ_TYPE_LEVEL_HIGH;
178
179 return 0;
180 }
181
182 static const struct irq_domain_ops gef_pic_host_ops = {
183 .map = gef_pic_host_map,
184 .xlate = gef_pic_host_xlate,
185 };
186
187
188 /*
189 * Initialisation of PIC, this should be called in BSP
190 */
gef_pic_init(struct device_node * np)191 void __init gef_pic_init(struct device_node *np)
192 {
193 unsigned long flags;
194
195 /* Map the devices registers into memory */
196 gef_pic_irq_reg_base = of_iomap(np, 0);
197
198 raw_spin_lock_irqsave(&gef_pic_lock, flags);
199
200 /* Initialise everything as masked. */
201 out_be32(gef_pic_irq_reg_base + GEF_PIC_CPU0_INTR_MASK, 0);
202 out_be32(gef_pic_irq_reg_base + GEF_PIC_CPU1_INTR_MASK, 0);
203
204 out_be32(gef_pic_irq_reg_base + GEF_PIC_CPU0_MCP_MASK, 0);
205 out_be32(gef_pic_irq_reg_base + GEF_PIC_CPU1_MCP_MASK, 0);
206
207 raw_spin_unlock_irqrestore(&gef_pic_lock, flags);
208
209 /* Map controller */
210 gef_pic_cascade_irq = irq_of_parse_and_map(np, 0);
211 if (!gef_pic_cascade_irq) {
212 printk(KERN_ERR "SBC610: failed to map cascade interrupt");
213 return;
214 }
215
216 /* Setup an irq_domain structure */
217 gef_pic_irq_host = irq_domain_add_linear(np, GEF_PIC_NUM_IRQS,
218 &gef_pic_host_ops, NULL);
219 if (gef_pic_irq_host == NULL)
220 return;
221
222 /* Chain with parent controller */
223 irq_set_chained_handler(gef_pic_cascade_irq, gef_pic_cascade);
224 }
225
226 /*
227 * This is called when we receive an interrupt with apparently comes from this
228 * chip - check, returning the highest interrupt generated or return 0.
229 */
gef_pic_get_irq(void)230 unsigned int gef_pic_get_irq(void)
231 {
232 u32 cause, mask, active;
233 unsigned int virq = 0;
234 int hwirq;
235
236 cause = in_be32(gef_pic_irq_reg_base + GEF_PIC_INTR_STATUS);
237
238 mask = in_be32(gef_pic_irq_reg_base + GEF_PIC_INTR_MASK(0));
239
240 active = cause & mask;
241
242 if (active) {
243 for (hwirq = GEF_PIC_NUM_IRQS - 1; hwirq > -1; hwirq--) {
244 if (active & (0x1 << hwirq))
245 break;
246 }
247 virq = irq_linear_revmap(gef_pic_irq_host,
248 (irq_hw_number_t)hwirq);
249 }
250
251 return virq;
252 }
253
254