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Linux/drivers/irqchip/irq-bcm2835.c

  1 /*
  2  * Copyright 2010 Broadcom
  3  * Copyright 2012 Simon Arlott, Chris Boot, Stephen Warren
  4  *
  5  * This program is free software; you can redistribute it and/or modify
  6  * it under the terms of the GNU General Public License as published by
  7  * the Free Software Foundation; either version 2 of the License, or
  8  * (at your option) any later version.
  9  *
 10  * This program is distributed in the hope that it will be useful,
 11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
 12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 13  * GNU General Public License for more details.
 14  *
 15  * Quirk 1: Shortcut interrupts don't set the bank 1/2 register pending bits
 16  *
 17  * If an interrupt fires on bank 1 that isn't in the shortcuts list, bit 8
 18  * on bank 0 is set to signify that an interrupt in bank 1 has fired, and
 19  * to look in the bank 1 status register for more information.
 20  *
 21  * If an interrupt fires on bank 1 that _is_ in the shortcuts list, its
 22  * shortcut bit in bank 0 is set as well as its interrupt bit in the bank 1
 23  * status register, but bank 0 bit 8 is _not_ set.
 24  *
 25  * Quirk 2: You can't mask the register 1/2 pending interrupts
 26  *
 27  * In a proper cascaded interrupt controller, the interrupt lines with
 28  * cascaded interrupt controllers on them are just normal interrupt lines.
 29  * You can mask the interrupts and get on with things. With this controller
 30  * you can't do that.
 31  *
 32  * Quirk 3: The shortcut interrupts can't be (un)masked in bank 0
 33  *
 34  * Those interrupts that have shortcuts can only be masked/unmasked in
 35  * their respective banks' enable/disable registers. Doing so in the bank 0
 36  * enable/disable registers has no effect.
 37  *
 38  * The FIQ control register:
 39  *  Bits 0-6: IRQ (index in order of interrupts from banks 1, 2, then 0)
 40  *  Bit    7: Enable FIQ generation
 41  *  Bits  8+: Unused
 42  *
 43  * An interrupt must be disabled before configuring it for FIQ generation
 44  * otherwise both handlers will fire at the same time!
 45  */
 46 
 47 #include <linux/io.h>
 48 #include <linux/slab.h>
 49 #include <linux/of_address.h>
 50 #include <linux/of_irq.h>
 51 #include <linux/irqchip.h>
 52 #include <linux/irqdomain.h>
 53 
 54 #include <asm/exception.h>
 55 
 56 /* Put the bank and irq (32 bits) into the hwirq */
 57 #define MAKE_HWIRQ(b, n)        ((b << 5) | (n))
 58 #define HWIRQ_BANK(i)           (i >> 5)
 59 #define HWIRQ_BIT(i)            BIT(i & 0x1f)
 60 
 61 #define NR_IRQS_BANK0           8
 62 #define BANK0_HWIRQ_MASK        0xff
 63 /* Shortcuts can't be disabled so any unknown new ones need to be masked */
 64 #define SHORTCUT1_MASK          0x00007c00
 65 #define SHORTCUT2_MASK          0x001f8000
 66 #define SHORTCUT_SHIFT          10
 67 #define BANK1_HWIRQ             BIT(8)
 68 #define BANK2_HWIRQ             BIT(9)
 69 #define BANK0_VALID_MASK        (BANK0_HWIRQ_MASK | BANK1_HWIRQ | BANK2_HWIRQ \
 70                                         | SHORTCUT1_MASK | SHORTCUT2_MASK)
 71 
 72 #define REG_FIQ_CONTROL         0x0c
 73 
 74 #define NR_BANKS                3
 75 #define IRQS_PER_BANK           32
 76 
 77 static const int reg_pending[] __initconst = { 0x00, 0x04, 0x08 };
 78 static const int reg_enable[] __initconst = { 0x18, 0x10, 0x14 };
 79 static const int reg_disable[] __initconst = { 0x24, 0x1c, 0x20 };
 80 static const int bank_irqs[] __initconst = { 8, 32, 32 };
 81 
 82 static const int shortcuts[] = {
 83         7, 9, 10, 18, 19,               /* Bank 1 */
 84         21, 22, 23, 24, 25, 30          /* Bank 2 */
 85 };
 86 
 87 struct armctrl_ic {
 88         void __iomem *base;
 89         void __iomem *pending[NR_BANKS];
 90         void __iomem *enable[NR_BANKS];
 91         void __iomem *disable[NR_BANKS];
 92         struct irq_domain *domain;
 93 };
 94 
 95 static struct armctrl_ic intc __read_mostly;
 96 static void __exception_irq_entry bcm2835_handle_irq(
 97         struct pt_regs *regs);
 98 static void bcm2836_chained_handle_irq(struct irq_desc *desc);
 99 
100 static void armctrl_mask_irq(struct irq_data *d)
101 {
102         writel_relaxed(HWIRQ_BIT(d->hwirq), intc.disable[HWIRQ_BANK(d->hwirq)]);
103 }
104 
105 static void armctrl_unmask_irq(struct irq_data *d)
106 {
107         writel_relaxed(HWIRQ_BIT(d->hwirq), intc.enable[HWIRQ_BANK(d->hwirq)]);
108 }
109 
110 static struct irq_chip armctrl_chip = {
111         .name = "ARMCTRL-level",
112         .irq_mask = armctrl_mask_irq,
113         .irq_unmask = armctrl_unmask_irq
114 };
115 
116 static int armctrl_xlate(struct irq_domain *d, struct device_node *ctrlr,
117         const u32 *intspec, unsigned int intsize,
118         unsigned long *out_hwirq, unsigned int *out_type)
119 {
120         if (WARN_ON(intsize != 2))
121                 return -EINVAL;
122 
123         if (WARN_ON(intspec[0] >= NR_BANKS))
124                 return -EINVAL;
125 
126         if (WARN_ON(intspec[1] >= IRQS_PER_BANK))
127                 return -EINVAL;
128 
129         if (WARN_ON(intspec[0] == 0 && intspec[1] >= NR_IRQS_BANK0))
130                 return -EINVAL;
131 
132         *out_hwirq = MAKE_HWIRQ(intspec[0], intspec[1]);
133         *out_type = IRQ_TYPE_NONE;
134         return 0;
135 }
136 
137 static const struct irq_domain_ops armctrl_ops = {
138         .xlate = armctrl_xlate
139 };
140 
141 static int __init armctrl_of_init(struct device_node *node,
142                                   struct device_node *parent,
143                                   bool is_2836)
144 {
145         void __iomem *base;
146         int irq, b, i;
147 
148         base = of_iomap(node, 0);
149         if (!base)
150                 panic("%s: unable to map IC registers\n",
151                         node->full_name);
152 
153         intc.domain = irq_domain_add_linear(node, MAKE_HWIRQ(NR_BANKS, 0),
154                         &armctrl_ops, NULL);
155         if (!intc.domain)
156                 panic("%s: unable to create IRQ domain\n", node->full_name);
157 
158         for (b = 0; b < NR_BANKS; b++) {
159                 intc.pending[b] = base + reg_pending[b];
160                 intc.enable[b] = base + reg_enable[b];
161                 intc.disable[b] = base + reg_disable[b];
162 
163                 for (i = 0; i < bank_irqs[b]; i++) {
164                         irq = irq_create_mapping(intc.domain, MAKE_HWIRQ(b, i));
165                         BUG_ON(irq <= 0);
166                         irq_set_chip_and_handler(irq, &armctrl_chip,
167                                 handle_level_irq);
168                         irq_set_probe(irq);
169                 }
170         }
171 
172         if (is_2836) {
173                 int parent_irq = irq_of_parse_and_map(node, 0);
174 
175                 if (!parent_irq) {
176                         panic("%s: unable to get parent interrupt.\n",
177                               node->full_name);
178                 }
179                 irq_set_chained_handler(parent_irq, bcm2836_chained_handle_irq);
180         } else {
181                 set_handle_irq(bcm2835_handle_irq);
182         }
183 
184         return 0;
185 }
186 
187 static int __init bcm2835_armctrl_of_init(struct device_node *node,
188                                           struct device_node *parent)
189 {
190         return armctrl_of_init(node, parent, false);
191 }
192 
193 static int __init bcm2836_armctrl_of_init(struct device_node *node,
194                                           struct device_node *parent)
195 {
196         return armctrl_of_init(node, parent, true);
197 }
198 
199 
200 /*
201  * Handle each interrupt across the entire interrupt controller.  This reads the
202  * status register before handling each interrupt, which is necessary given that
203  * handle_IRQ may briefly re-enable interrupts for soft IRQ handling.
204  */
205 
206 static u32 armctrl_translate_bank(int bank)
207 {
208         u32 stat = readl_relaxed(intc.pending[bank]);
209 
210         return MAKE_HWIRQ(bank, ffs(stat) - 1);
211 }
212 
213 static u32 armctrl_translate_shortcut(int bank, u32 stat)
214 {
215         return MAKE_HWIRQ(bank, shortcuts[ffs(stat >> SHORTCUT_SHIFT) - 1]);
216 }
217 
218 static u32 get_next_armctrl_hwirq(void)
219 {
220         u32 stat = readl_relaxed(intc.pending[0]) & BANK0_VALID_MASK;
221 
222         if (stat == 0)
223                 return ~0;
224         else if (stat & BANK0_HWIRQ_MASK)
225                 return MAKE_HWIRQ(0, ffs(stat & BANK0_HWIRQ_MASK) - 1);
226         else if (stat & SHORTCUT1_MASK)
227                 return armctrl_translate_shortcut(1, stat & SHORTCUT1_MASK);
228         else if (stat & SHORTCUT2_MASK)
229                 return armctrl_translate_shortcut(2, stat & SHORTCUT2_MASK);
230         else if (stat & BANK1_HWIRQ)
231                 return armctrl_translate_bank(1);
232         else if (stat & BANK2_HWIRQ)
233                 return armctrl_translate_bank(2);
234         else
235                 BUG();
236 }
237 
238 static void __exception_irq_entry bcm2835_handle_irq(
239         struct pt_regs *regs)
240 {
241         u32 hwirq;
242 
243         while ((hwirq = get_next_armctrl_hwirq()) != ~0)
244                 handle_domain_irq(intc.domain, hwirq, regs);
245 }
246 
247 static void bcm2836_chained_handle_irq(struct irq_desc *desc)
248 {
249         u32 hwirq;
250 
251         while ((hwirq = get_next_armctrl_hwirq()) != ~0)
252                 generic_handle_irq(irq_linear_revmap(intc.domain, hwirq));
253 }
254 
255 IRQCHIP_DECLARE(bcm2835_armctrl_ic, "brcm,bcm2835-armctrl-ic",
256                 bcm2835_armctrl_of_init);
257 IRQCHIP_DECLARE(bcm2836_armctrl_ic, "brcm,bcm2836-armctrl-ic",
258                 bcm2836_armctrl_of_init);
259 

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