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  */
  47 static unsigned long ilsel_level_map;
  48
  49 static inline unsigned int ilsel_offset(unsigned int bit)
  50 {
  51         return ILSEL_LEVELS - bit - 1;
  52 }
  53
  54 static inline unsigned long mk_ilsel_addr(unsigned int bit)
  55 {
  56         return ILSEL_BASE + ((ilsel_offset(bit) >> 1) & ~0x1);
  57 }
  58
  59 static inline unsigned int mk_ilsel_shift(unsigned int bit)
  60 {
  61         return (ilsel_offset(bit) & 0x3) << 2;
  62 }
  63
  64 static 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  */
  95 int 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 }
 112 EXPORT_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  */
 125 int 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 }
 136 EXPORT_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  */
 144 void 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 }
 159 EXPORT_SYMBOL_GPL(ilsel_disable);