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);
157