root/arch/powerpc/sysdev/i8259.c

DEFINITIONS

1. i8259_irq
2. i8259_mask_and_ack_irq
3. i8259_set_irq_mask
4. i8259_mask_irq
5. i8259_unmask_irq
6. i8259_host_match
7. i8259_host_map
8. i8259_host_xlate
9. i8259_get_host
10. i8259_init

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * i8259 interrupt controller driver.
   4  */
   5 #undef DEBUG
   6 
   7 #include <linux/ioport.h>
   8 #include <linux/interrupt.h>
   9 #include <linux/kernel.h>
  10 #include <linux/delay.h>
  11 #include <asm/io.h>
  12 #include <asm/i8259.h>
  13 #include <asm/prom.h>
  14 
  15 static volatile void __iomem *pci_intack; /* RO, gives us the irq vector */
  16 
  17 static unsigned char cached_8259[2] = { 0xff, 0xff };
  18 #define cached_A1 (cached_8259[0])
  19 #define cached_21 (cached_8259[1])
  20 
  21 static DEFINE_RAW_SPINLOCK(i8259_lock);
  22 
  23 static struct irq_domain *i8259_host;
  24 
  25 /*
  26  * Acknowledge the IRQ using either the PCI host bridge's interrupt
  27  * acknowledge feature or poll.  How i8259_init() is called determines
  28  * which is called.  It should be noted that polling is broken on some
  29  * IBM and Motorola PReP boxes so we must use the int-ack feature on them.
  30  */
  31 unsigned int i8259_irq(void)
  32 {
  33         int irq;
  34         int lock = 0;
  35 
  36         /* Either int-ack or poll for the IRQ */
  37         if (pci_intack)
  38                 irq = readb(pci_intack);
  39         else {
  40                 raw_spin_lock(&i8259_lock);
  41                 lock = 1;
  42 
  43                 /* Perform an interrupt acknowledge cycle on controller 1. */
  44                 outb(0x0C, 0x20);               /* prepare for poll */
  45                 irq = inb(0x20) & 7;
  46                 if (irq == 2 ) {
  47                         /*
  48                          * Interrupt is cascaded so perform interrupt
  49                          * acknowledge on controller 2.
  50                          */
  51                         outb(0x0C, 0xA0);       /* prepare for poll */
  52                         irq = (inb(0xA0) & 7) + 8;
  53                 }
  54         }
  55 
  56         if (irq == 7) {
  57                 /*
  58                  * This may be a spurious interrupt.
  59                  *
  60                  * Read the interrupt status register (ISR). If the most
  61                  * significant bit is not set then there is no valid
  62                  * interrupt.
  63                  */
  64                 if (!pci_intack)
  65                         outb(0x0B, 0x20);       /* ISR register */
  66                 if(~inb(0x20) & 0x80)
  67                         irq = 0;
  68         } else if (irq == 0xff)
  69                 irq = 0;
  70 
  71         if (lock)
  72                 raw_spin_unlock(&i8259_lock);
  73         return irq;
  74 }
  75 
  76 static void i8259_mask_and_ack_irq(struct irq_data *d)
  77 {
  78         unsigned long flags;
  79 
  80         raw_spin_lock_irqsave(&i8259_lock, flags);
  81         if (d->irq > 7) {
  82                 cached_A1 |= 1 << (d->irq-8);
  83                 inb(0xA1);      /* DUMMY */
  84                 outb(cached_A1, 0xA1);
  85                 outb(0x20, 0xA0);       /* Non-specific EOI */
  86                 outb(0x20, 0x20);       /* Non-specific EOI to cascade */
  87         } else {
  88                 cached_21 |= 1 << d->irq;
  89                 inb(0x21);      /* DUMMY */
  90                 outb(cached_21, 0x21);
  91                 outb(0x20, 0x20);       /* Non-specific EOI */
  92         }
  93         raw_spin_unlock_irqrestore(&i8259_lock, flags);
  94 }
  95 
  96 static void i8259_set_irq_mask(int irq_nr)
  97 {
  98         outb(cached_A1,0xA1);
  99         outb(cached_21,0x21);
 100 }
 101 
 102 static void i8259_mask_irq(struct irq_data *d)
 103 {
 104         unsigned long flags;
 105 
 106         pr_debug("i8259_mask_irq(%d)\n", d->irq);
 107 
 108         raw_spin_lock_irqsave(&i8259_lock, flags);
 109         if (d->irq < 8)
 110                 cached_21 |= 1 << d->irq;
 111         else
 112                 cached_A1 |= 1 << (d->irq-8);
 113         i8259_set_irq_mask(d->irq);
 114         raw_spin_unlock_irqrestore(&i8259_lock, flags);
 115 }
 116 
 117 static void i8259_unmask_irq(struct irq_data *d)
 118 {
 119         unsigned long flags;
 120 
 121         pr_debug("i8259_unmask_irq(%d)\n", d->irq);
 122 
 123         raw_spin_lock_irqsave(&i8259_lock, flags);
 124         if (d->irq < 8)
 125                 cached_21 &= ~(1 << d->irq);
 126         else
 127                 cached_A1 &= ~(1 << (d->irq-8));
 128         i8259_set_irq_mask(d->irq);
 129         raw_spin_unlock_irqrestore(&i8259_lock, flags);
 130 }
 131 
 132 static struct irq_chip i8259_pic = {
 133         .name           = "i8259",
 134         .irq_mask       = i8259_mask_irq,
 135         .irq_disable    = i8259_mask_irq,
 136         .irq_unmask     = i8259_unmask_irq,
 137         .irq_mask_ack   = i8259_mask_and_ack_irq,
 138 };
 139 
 140 static struct resource pic1_iores = {
 141         .name = "8259 (master)",
 142         .start = 0x20,
 143         .end = 0x21,
 144         .flags = IORESOURCE_IO | IORESOURCE_BUSY,
 145 };
 146 
 147 static struct resource pic2_iores = {
 148         .name = "8259 (slave)",
 149         .start = 0xa0,
 150         .end = 0xa1,
 151         .flags = IORESOURCE_IO | IORESOURCE_BUSY,
 152 };
 153 
 154 static struct resource pic_edgectrl_iores = {
 155         .name = "8259 edge control",
 156         .start = 0x4d0,
 157         .end = 0x4d1,
 158         .flags = IORESOURCE_IO | IORESOURCE_BUSY,
 159 };
 160 
 161 static int i8259_host_match(struct irq_domain *h, struct device_node *node,
 162                             enum irq_domain_bus_token bus_token)
 163 {
 164         struct device_node *of_node = irq_domain_get_of_node(h);
 165         return of_node == NULL || of_node == node;
 166 }
 167 
 168 static int i8259_host_map(struct irq_domain *h, unsigned int virq,
 169                           irq_hw_number_t hw)
 170 {
 171         pr_debug("i8259_host_map(%d, 0x%lx)\n", virq, hw);
 172 
 173         /* We block the internal cascade */
 174         if (hw == 2)
 175                 irq_set_status_flags(virq, IRQ_NOREQUEST);
 176 
 177         /* We use the level handler only for now, we might want to
 178          * be more cautious here but that works for now
 179          */
 180         irq_set_status_flags(virq, IRQ_LEVEL);
 181         irq_set_chip_and_handler(virq, &i8259_pic, handle_level_irq);
 182         return 0;
 183 }
 184 
 185 static int i8259_host_xlate(struct irq_domain *h, struct device_node *ct,
 186                             const u32 *intspec, unsigned int intsize,
 187                             irq_hw_number_t *out_hwirq, unsigned int *out_flags)
 188 {
 189         static unsigned char map_isa_senses[4] = {
 190                 IRQ_TYPE_LEVEL_LOW,
 191                 IRQ_TYPE_LEVEL_HIGH,
 192                 IRQ_TYPE_EDGE_FALLING,
 193                 IRQ_TYPE_EDGE_RISING,
 194         };
 195 
 196         *out_hwirq = intspec[0];
 197         if (intsize > 1 && intspec[1] < 4)
 198                 *out_flags = map_isa_senses[intspec[1]];
 199         else
 200                 *out_flags = IRQ_TYPE_NONE;
 201 
 202         return 0;
 203 }
 204 
 205 static const struct irq_domain_ops i8259_host_ops = {
 206         .match = i8259_host_match,
 207         .map = i8259_host_map,
 208         .xlate = i8259_host_xlate,
 209 };
 210 
 211 struct irq_domain *i8259_get_host(void)
 212 {
 213         return i8259_host;
 214 }
 215 
 216 /**
 217  * i8259_init - Initialize the legacy controller
 218  * @node: device node of the legacy PIC (can be NULL, but then, it will match
 219  *        all interrupts, so beware)
 220  * @intack_addr: PCI interrupt acknowledge (real) address which will return
 221  *               the active irq from the 8259
 222  */
 223 void i8259_init(struct device_node *node, unsigned long intack_addr)
 224 {
 225         unsigned long flags;
 226 
 227         /* initialize the controller */
 228         raw_spin_lock_irqsave(&i8259_lock, flags);
 229 
 230         /* Mask all first */
 231         outb(0xff, 0xA1);
 232         outb(0xff, 0x21);
 233 
 234         /* init master interrupt controller */
 235         outb(0x11, 0x20); /* Start init sequence */
 236         outb(0x00, 0x21); /* Vector base */
 237         outb(0x04, 0x21); /* edge triggered, Cascade (slave) on IRQ2 */
 238         outb(0x01, 0x21); /* Select 8086 mode */
 239 
 240         /* init slave interrupt controller */
 241         outb(0x11, 0xA0); /* Start init sequence */
 242         outb(0x08, 0xA1); /* Vector base */
 243         outb(0x02, 0xA1); /* edge triggered, Cascade (slave) on IRQ2 */
 244         outb(0x01, 0xA1); /* Select 8086 mode */
 245 
 246         /* That thing is slow */
 247         udelay(100);
 248 
 249         /* always read ISR */
 250         outb(0x0B, 0x20);
 251         outb(0x0B, 0xA0);
 252 
 253         /* Unmask the internal cascade */
 254         cached_21 &= ~(1 << 2);
 255 
 256         /* Set interrupt masks */
 257         outb(cached_A1, 0xA1);
 258         outb(cached_21, 0x21);
 259 
 260         raw_spin_unlock_irqrestore(&i8259_lock, flags);
 261 
 262         /* create a legacy host */
 263         i8259_host = irq_domain_add_legacy_isa(node, &i8259_host_ops, NULL);
 264         if (i8259_host == NULL) {
 265                 printk(KERN_ERR "i8259: failed to allocate irq host !\n");
 266                 return;
 267         }
 268 
 269         /* reserve our resources */
 270         /* XXX should we continue doing that ? it seems to cause problems
 271          * with further requesting of PCI IO resources for that range...
 272          * need to look into it.
 273          */
 274         request_resource(&ioport_resource, &pic1_iores);
 275         request_resource(&ioport_resource, &pic2_iores);
 276         request_resource(&ioport_resource, &pic_edgectrl_iores);
 277 
 278         if (intack_addr != 0)
 279                 pci_intack = ioremap(intack_addr, 1);
 280 
 281         printk(KERN_INFO "i8259 legacy interrupt controller initialized\n");
 282 }