LXR linux/arch/sh/boards/mach-x3proto/ilsel.c

   1/*
   2 * arch/sh/boards/mach-x3proto/ilsel.c
   3 *
   4 * Helper routines for SH-X3 proto board ILSEL.
   5 *
   6 * Copyright (C) 2007 - 2010  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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  13
  14#include <linux/init.h>
  15#include <linux/kernel.h>
  16#include <linux/module.h>
  17#include <linux/bitmap.h>
  18#include <linux/io.h>
  19#include <mach/ilsel.h>
  20
  21/*
  22 * ILSEL is split across:
  23 *
  24 *      ILSEL0 - 0xb8100004 [ Levels  1 -  4 ]
  25 *      ILSEL1 - 0xb8100006 [ Levels  5 -  8 ]
  26 *      ILSEL2 - 0xb8100008 [ Levels  9 - 12 ]
  27 *      ILSEL3 - 0xb810000a [ Levels 13 - 15 ]
  28 *
  29 * With each level being relative to an ilsel_source_t.
  30 */
  31#define ILSEL_BASE      0xb8100004
  32#define ILSEL_LEVELS    15
  33
  34/*
  35 * ILSEL level map, in descending order from the highest level down.
  36 *
  37 * Supported levels are 1 - 15 spread across ILSEL0 - ILSEL4, mapping
  38 * directly to IRLs. As the IRQs are numbered in reverse order relative
  39 * to the interrupt level, the level map is carefully managed to ensure a
  40 * 1:1 mapping between the bit position and the IRQ number.
  41 *
  42 * This careful constructions allows ilsel_enable*() to be referenced
  43 * directly for hooking up an ILSEL set and getting back an IRQ which can
  44 * subsequently be used for internal accounting in the (optional) disable
  45 * path.
  46 */
  47static unsigned long ilsel_level_map;
  48
  49static inline unsigned int ilsel_offset(unsigned int bit)
  50{
  51        return ILSEL_LEVELS - bit - 1;
  52}
  53
  54static inline unsigned long mk_ilsel_addr(unsigned int bit)
  55{
  56        return ILSEL_BASE + ((ilsel_offset(bit) >> 1) & ~0x1);
  57}
  58
  59static inline unsigned int mk_ilsel_shift(unsigned int bit)
  60{
  61        return (ilsel_offset(bit) & 0x3) << 2;
  62}
  63
  64static void __ilsel_enable(ilsel_source_t set, unsigned int bit)
  65{
  66        unsigned int tmp, shift;
  67        unsigned long addr;
  68
  69        pr_notice("enabling ILSEL set %d\n", set);
  70
  71        addr = mk_ilsel_addr(bit);
  72        shift = mk_ilsel_shift(bit);
  73
  74        pr_debug("%s: bit#%d: addr - 0x%08lx (shift %d, set %d)\n",
  75                 __func__, bit, addr, shift, set);
  76
  77        tmp = __raw_readw(addr);
  78        tmp &= ~(0xf << shift);
  79        tmp |= set << shift;
  80        __raw_writew(tmp, addr);
  81}
  82
  83/**
  84 * ilsel_enable - Enable an ILSEL set.
  85 * @set: ILSEL source (see ilsel_source_t enum in include/asm-sh/ilsel.h).
  86 *
  87 * Enables a given non-aliased ILSEL source (<= ILSEL_KEY) at the highest
  88 * available interrupt level. Callers should take care to order callsites
  89 * noting descending interrupt levels. Aliasing FPGA and external board
  90 * IRQs need to use ilsel_enable_fixed().
  91 *
  92 * The return value is an IRQ number that can later be taken down with
  93 * ilsel_disable().
  94 */
  95int ilsel_enable(ilsel_source_t set)
  96{
  97        unsigned int bit;
  98
  99        if (unlikely(set > ILSEL_KEY)) {
 100                pr_err("Aliased sources must use ilsel_enable_fixed()\n");
 101                return -EINVAL;
 102        }
 103
 104        do {
 105                bit = find_first_zero_bit(&ilsel_level_map, ILSEL_LEVELS);
 106        } while (test_and_set_bit(bit, &ilsel_level_map));
 107
 108        __ilsel_enable(set, bit);
 109
 110        return bit;
 111}
 112EXPORT_SYMBOL_GPL(ilsel_enable);
 113
 114/**
 115 * ilsel_enable_fixed - Enable an ILSEL set at a fixed interrupt level
 116 * @set: ILSEL source (see ilsel_source_t enum in include/asm-sh/ilsel.h).
 117 * @level: Interrupt level (1 - 15)
 118 *
 119 * Enables a given ILSEL source at a fixed interrupt level. Necessary
 120 * both for level reservation as well as for aliased sources that only
 121 * exist on special ILSEL#s.
 122 *
 123 * Returns an IRQ number (as ilsel_enable()).
 124 */
 125int ilsel_enable_fixed(ilsel_source_t set, unsigned int level)
 126{
 127        unsigned int bit = ilsel_offset(level - 1);
 128
 129        if (test_and_set_bit(bit, &ilsel_level_map))
 130                return -EBUSY;
 131
 132        __ilsel_enable(set, bit);
 133
 134        return bit;
 135}
 136EXPORT_SYMBOL_GPL(ilsel_enable_fixed);
 137
 138/**
 139 * ilsel_disable - Disable an ILSEL set
 140 * @irq: Bit position for ILSEL set value (retval from enable routines)
 141 *
 142 * Disable a previously enabled ILSEL set.
 143 */
 144void ilsel_disable(unsigned int irq)
 145{
 146        unsigned long addr;
 147        unsigned int tmp;
 148
 149        pr_notice("disabling ILSEL set %d\n", irq);
 150
 151        addr = mk_ilsel_addr(irq);
 152
 153        tmp = __raw_readw(addr);
 154        tmp &= ~(0xf << mk_ilsel_shift(irq));
 155        __raw_writew(tmp, addr);
 156
 157        clear_bit(irq, &ilsel_level_map);
 158}
 159EXPORT_SYMBOL_GPL(ilsel_disable);
 160