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