drivers/irqchip/irq-versatile-fpga.c

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