arch/sh/boards/renesas/x3proto/ilsel.c

   1 /*
   2  * arch/sh/boards/renesas/x3proto/ilsel.c
   3  *
   4  * Helper routines for SH-X3 proto board ILSEL.
   5  *
   6  * Copyright (C) 2007 Paul Mundt
   7  *
   8  * This file is subject to the terms and conditions of the GNU General Public
   9  * License.  See the file "COPYING" in the main directory of this archive
  10  * for more details.
  11  */
  12 #include <linux/init.h>
  13 #include <linux/kernel.h>
  14 #include <linux/module.h>
  15 #include <linux/bitmap.h>
  16 #include <linux/io.h>
  17 #include <asm/ilsel.h>
  18
  19 /*
  20  * ILSEL is split across:
  21  *
  22  *      ILSEL0 - 0xb8100004 [ Levels  1 -  4 ]
  23  *      ILSEL1 - 0xb8100006 [ Levels  5 -  8 ]
  24  *      ILSEL2 - 0xb8100008 [ Levels  9 - 12 ]
  25  *      ILSEL3 - 0xb810000a [ Levels 13 - 15 ]
  26  *
  27  * With each level being relative to an ilsel_source_t.
  28  */
  29 #define ILSEL_BASE      0xb8100004
  30 #define ILSEL_LEVELS    15
  31
  32 /*
  33  * ILSEL level map, in descending order from the highest level down.
  34  *
  35  * Supported levels are 1 - 15 spread across ILSEL0 - ILSEL4, mapping
  36  * directly to IRLs. As the IRQs are numbered in reverse order relative
  37  * to the interrupt level, the level map is carefully managed to ensure a
  38  * 1:1 mapping between the bit position and the IRQ number.
  39  *
  40  * This careful constructions allows ilsel_enable*() to be referenced
  41  * directly for hooking up an ILSEL set and getting back an IRQ which can
  42  * subsequently be used for internal accounting in the (optional) disable
  43  * path.
  44  */
  45 static unsigned long ilsel_level_map;
  46
  47 static inline unsigned int ilsel_offset(unsigned int bit)
  48 {
  49         return ILSEL_LEVELS - bit - 1;
  50 }
  51
  52 static inline unsigned long mk_ilsel_addr(unsigned int bit)
  53 {
  54         return ILSEL_BASE + ((ilsel_offset(bit) >> 1) & ~0x1);
  55 }
  56
  57 static inline unsigned int mk_ilsel_shift(unsigned int bit)
  58 {
  59         return (ilsel_offset(bit) & 0x3) << 2;
  60 }
  61
  62 static void __ilsel_enable(ilsel_source_t set, unsigned int bit)
  63 {
  64         unsigned int tmp, shift;
  65         unsigned long addr;
  66
  67         addr = mk_ilsel_addr(bit);
  68         shift = mk_ilsel_shift(bit);
  69
  70         pr_debug("%s: bit#%d: addr - 0x%08lx (shift %d, set %d)\n",
  71                  __func__, bit, addr, shift, set);
  72
  73         tmp = ctrl_inw(addr);
  74         tmp &= ~(0xf << shift);
  75         tmp |= set << shift;
  76         ctrl_outw(tmp, addr);
  77 }
  78
  79 /**
  80  * ilsel_enable - Enable an ILSEL set.
  81  * @set: ILSEL source (see ilsel_source_t enum in include/asm-sh/ilsel.h).
  82  *
  83  * Enables a given non-aliased ILSEL source (<= ILSEL_KEY) at the highest
  84  * available interrupt level. Callers should take care to order callsites
  85  * noting descending interrupt levels. Aliasing FPGA and external board
  86  * IRQs need to use ilsel_enable_fixed().
  87  *
  88  * The return value is an IRQ number that can later be taken down with
  89  * ilsel_disable().
  90  */
  91 int ilsel_enable(ilsel_source_t set)
  92 {
  93         unsigned int bit;
  94
  95         /* Aliased sources must use ilsel_enable_fixed() */
  96         BUG_ON(set > ILSEL_KEY);
  97
  98         do {
  99                 bit = find_first_zero_bit(&ilsel_level_map, ILSEL_LEVELS);
 100         } while (test_and_set_bit(bit, &ilsel_level_map));
 101
 102         __ilsel_enable(set, bit);
 103
 104         return bit;
 105 }
 106 EXPORT_SYMBOL_GPL(ilsel_enable);
 107
 108 /**
 109  * ilsel_enable_fixed - Enable an ILSEL set at a fixed interrupt level
 110  * @set: ILSEL source (see ilsel_source_t enum in include/asm-sh/ilsel.h).
 111  * @level: Interrupt level (1 - 15)
 112  *
 113  * Enables a given ILSEL source at a fixed interrupt level. Necessary
 114  * both for level reservation as well as for aliased sources that only
 115  * exist on special ILSEL#s.
 116  *
 117  * Returns an IRQ number (as ilsel_enable()).
 118  */
 119 int ilsel_enable_fixed(ilsel_source_t set, unsigned int level)
 120 {
 121         unsigned int bit = ilsel_offset(level - 1);
 122
 123         if (test_and_set_bit(bit, &ilsel_level_map))
 124                 return -EBUSY;
 125
 126         __ilsel_enable(set, bit);
 127
 128         return bit;
 129 }
 130 EXPORT_SYMBOL_GPL(ilsel_enable_fixed);
 131
 132 /**
 133  * ilsel_disable - Disable an ILSEL set
 134  * @irq: Bit position for ILSEL set value (retval from enable routines)
 135  *
 136  * Disable a previously enabled ILSEL set.
 137  */
 138 void ilsel_disable(unsigned int irq)
 139 {
 140         unsigned long addr;
 141         unsigned int tmp;
 142
 143         addr = mk_ilsel_addr(irq);
 144
 145         tmp = ctrl_inw(addr);
 146         tmp &= ~(0xf << mk_ilsel_shift(irq));
 147         ctrl_outw(tmp, addr);
 148
 149         clear_bit(irq, &ilsel_level_map);
 150 }
 151 EXPORT_SYMBOL_GPL(ilsel_disable);