1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * arch/sh/boards/mach-x3proto/ilsel.c
4 *
5 * Helper routines for SH-X3 proto board ILSEL.
6 *
7 * Copyright (C) 2007 - 2010 Paul Mundt
8 */
9 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
10
11 #include <linux/init.h>
12 #include <linux/kernel.h>
13 #include <linux/module.h>
14 #include <linux/bitmap.h>
15 #include <linux/io.h>
16 #include <mach/ilsel.h>
17
18 /*
19 * ILSEL is split across:
20 *
21 * ILSEL0 - 0xb8100004 [ Levels 1 - 4 ]
22 * ILSEL1 - 0xb8100006 [ Levels 5 - 8 ]
23 * ILSEL2 - 0xb8100008 [ Levels 9 - 12 ]
24 * ILSEL3 - 0xb810000a [ Levels 13 - 15 ]
25 *
26 * With each level being relative to an ilsel_source_t.
27 */
28 #define ILSEL_BASE 0xb8100004
29 #define ILSEL_LEVELS 15
30
31 /*
32 * ILSEL level map, in descending order from the highest level down.
33 *
34 * Supported levels are 1 - 15 spread across ILSEL0 - ILSEL4, mapping
35 * directly to IRLs. As the IRQs are numbered in reverse order relative
36 * to the interrupt level, the level map is carefully managed to ensure a
37 * 1:1 mapping between the bit position and the IRQ number.
38 *
39 * This careful constructions allows ilsel_enable*() to be referenced
40 * directly for hooking up an ILSEL set and getting back an IRQ which can
41 * subsequently be used for internal accounting in the (optional) disable
42 * path.
43 */
44 static unsigned long ilsel_level_map;
45
46 static inline unsigned int ilsel_offset(unsigned int bit)
47 {
48 return ILSEL_LEVELS - bit - 1;
49 }
50
51 static inline unsigned long mk_ilsel_addr(unsigned int bit)
52 {
53 return ILSEL_BASE + ((ilsel_offset(bit) >> 1) & ~0x1);
54 }
55
56 static inline unsigned int mk_ilsel_shift(unsigned int bit)
57 {
58 return (ilsel_offset(bit) & 0x3) << 2;
59 }
60
61 static void __ilsel_enable(ilsel_source_t set, unsigned int bit)
62 {
63 unsigned int tmp, shift;
64 unsigned long addr;
65
66 pr_notice("enabling ILSEL set %d\n", set);
67
68 addr = mk_ilsel_addr(bit);
69 shift = mk_ilsel_shift(bit);
70
71 pr_debug("%s: bit#%d: addr - 0x%08lx (shift %d, set %d)\n",
72 __func__, bit, addr, shift, set);
73
74 tmp = __raw_readw(addr);
75 tmp &= ~(0xf << shift);
76 tmp |= set << shift;
77 __raw_writew(tmp, addr);
78 }
79
80 /**
81 * ilsel_enable - Enable an ILSEL set.
82 * @set: ILSEL source (see ilsel_source_t enum in include/asm-sh/ilsel.h).
83 *
84 * Enables a given non-aliased ILSEL source (<= ILSEL_KEY) at the highest
85 * available interrupt level. Callers should take care to order callsites
86 * noting descending interrupt levels. Aliasing FPGA and external board
87 * IRQs need to use ilsel_enable_fixed().
88 *
89 * The return value is an IRQ number that can later be taken down with
90 * ilsel_disable().
91 */
92 int ilsel_enable(ilsel_source_t set)
93 {
94 unsigned int bit;
95
96 if (unlikely(set > ILSEL_KEY)) {
97 pr_err("Aliased sources must use ilsel_enable_fixed()\n");
98 return -EINVAL;
99 }
100
101 do {
102 bit = find_first_zero_bit(&ilsel_level_map, ILSEL_LEVELS);
103 } while (test_and_set_bit(bit, &ilsel_level_map));
104
105 __ilsel_enable(set, bit);
106
107 return bit;
108 }
109 EXPORT_SYMBOL_GPL(ilsel_enable);
110
111 /**
112 * ilsel_enable_fixed - Enable an ILSEL set at a fixed interrupt level
113 * @set: ILSEL source (see ilsel_source_t enum in include/asm-sh/ilsel.h).
114 * @level: Interrupt level (1 - 15)
115 *
116 * Enables a given ILSEL source at a fixed interrupt level. Necessary
117 * both for level reservation as well as for aliased sources that only
118 * exist on special ILSEL#s.
119 *
120 * Returns an IRQ number (as ilsel_enable()).
121 */
122 int ilsel_enable_fixed(ilsel_source_t set, unsigned int level)
123 {
124 unsigned int bit = ilsel_offset(level - 1);
125
126 if (test_and_set_bit(bit, &ilsel_level_map))
127 return -EBUSY;
128
129 __ilsel_enable(set, bit);
130
131 return bit;
132 }
133 EXPORT_SYMBOL_GPL(ilsel_enable_fixed);
134
135 /**
136 * ilsel_disable - Disable an ILSEL set
137 * @irq: Bit position for ILSEL set value (retval from enable routines)
138 *
139 * Disable a previously enabled ILSEL set.
140 */
141 void ilsel_disable(unsigned int irq)
142 {
143 unsigned long addr;
144 unsigned int tmp;
145
146 pr_notice("disabling ILSEL set %d\n", irq);
147
148 addr = mk_ilsel_addr(irq);
149
150 tmp = __raw_readw(addr);
151 tmp &= ~(0xf << mk_ilsel_shift(irq));
152 __raw_writew(tmp, addr);
153
154 clear_bit(irq, &ilsel_level_map);
155 }
156 EXPORT_SYMBOL_GPL(ilsel_disable);