summaryrefslogtreecommitdiff
path: root/drivers/clk/versatile/clk-sp810.c
blob: 64b0129a0216f3b8d7bb524b7b1688c9c0228d68 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
/*
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * Copyright (C) 2013 ARM Limited
 */

#include <linux/amba/sp810.h>
#include <linux/slab.h>
#include <linux/clk.h>
#include <linux/clk-provider.h>
#include <linux/err.h>
#include <linux/of.h>
#include <linux/of_address.h>

#define to_clk_sp810_timerclken(_hw) \
		container_of(_hw, struct clk_sp810_timerclken, hw)

struct clk_sp810;

struct clk_sp810_timerclken {
	struct clk_hw hw;
	struct clk *clk;
	struct clk_sp810 *sp810;
	int channel;
};

struct clk_sp810 {
	struct device_node *node;
	int refclk_index, timclk_index;
	void __iomem *base;
	spinlock_t lock;
	struct clk_sp810_timerclken timerclken[4];
	struct clk *refclk;
	struct clk *timclk;
};

static u8 clk_sp810_timerclken_get_parent(struct clk_hw *hw)
{
	struct clk_sp810_timerclken *timerclken = to_clk_sp810_timerclken(hw);
	u32 val = readl(timerclken->sp810->base + SCCTRL);

	return !!(val & (1 << SCCTRL_TIMERENnSEL_SHIFT(timerclken->channel)));
}

static int clk_sp810_timerclken_set_parent(struct clk_hw *hw, u8 index)
{
	struct clk_sp810_timerclken *timerclken = to_clk_sp810_timerclken(hw);
	struct clk_sp810 *sp810 = timerclken->sp810;
	u32 val, shift = SCCTRL_TIMERENnSEL_SHIFT(timerclken->channel);
	unsigned long flags = 0;

	if (WARN_ON(index > 1))
		return -EINVAL;

	spin_lock_irqsave(&sp810->lock, flags);

	val = readl(sp810->base + SCCTRL);
	val &= ~(1 << shift);
	val |= index << shift;
	writel(val, sp810->base + SCCTRL);

	spin_unlock_irqrestore(&sp810->lock, flags);

	return 0;
}

/*
 * FIXME - setting the parent every time .prepare is invoked is inefficient.
 * This is better handled by a dedicated clock tree configuration mechanism at
 * init-time.  Revisit this later when such a mechanism exists
 */
static int clk_sp810_timerclken_prepare(struct clk_hw *hw)
{
	struct clk_sp810_timerclken *timerclken = to_clk_sp810_timerclken(hw);
	struct clk_sp810 *sp810 = timerclken->sp810;
	struct clk *old_parent = __clk_get_parent(hw->clk);
	struct clk *new_parent;

	if (!sp810->refclk)
		sp810->refclk = of_clk_get(sp810->node, sp810->refclk_index);

	if (!sp810->timclk)
		sp810->timclk = of_clk_get(sp810->node, sp810->timclk_index);

	if (WARN_ON(IS_ERR(sp810->refclk) || IS_ERR(sp810->timclk)))
		return -ENOENT;

	/* Select fastest parent */
	if (clk_get_rate(sp810->refclk) > clk_get_rate(sp810->timclk))
		new_parent = sp810->refclk;
	else
		new_parent = sp810->timclk;

	/* Switch the parent if necessary */
	if (old_parent != new_parent) {
		clk_prepare(new_parent);
		clk_set_parent(hw->clk, new_parent);
		clk_unprepare(old_parent);
	}

	return 0;
}

static void clk_sp810_timerclken_unprepare(struct clk_hw *hw)
{
	struct clk_sp810_timerclken *timerclken = to_clk_sp810_timerclken(hw);
	struct clk_sp810 *sp810 = timerclken->sp810;

	clk_put(sp810->timclk);
	clk_put(sp810->refclk);
}

static const struct clk_ops clk_sp810_timerclken_ops = {
	.prepare = clk_sp810_timerclken_prepare,
	.unprepare = clk_sp810_timerclken_unprepare,
	.get_parent = clk_sp810_timerclken_get_parent,
	.set_parent = clk_sp810_timerclken_set_parent,
};

static struct clk *clk_sp810_timerclken_of_get(struct of_phandle_args *clkspec,
		void *data)
{
	struct clk_sp810 *sp810 = data;

	if (WARN_ON(clkspec->args_count != 1 || clkspec->args[0] >
			ARRAY_SIZE(sp810->timerclken)))
		return NULL;

	return sp810->timerclken[clkspec->args[0]].clk;
}

static void __init clk_sp810_of_setup(struct device_node *node)
{
	struct clk_sp810 *sp810 = kzalloc(sizeof(*sp810), GFP_KERNEL);
	const char *parent_names[2];
	char name[12];
	struct clk_init_data init;
	int i;

	if (!sp810) {
		pr_err("Failed to allocate memory for SP810!\n");
		return;
	}

	sp810->refclk_index = of_property_match_string(node, "clock-names",
			"refclk");
	parent_names[0] = of_clk_get_parent_name(node, sp810->refclk_index);

	sp810->timclk_index = of_property_match_string(node, "clock-names",
			"timclk");
	parent_names[1] = of_clk_get_parent_name(node, sp810->timclk_index);

	if (!parent_names[0] || !parent_names[1]) {
		pr_warn("Failed to obtain parent clocks for SP810!\n");
		return;
	}

	sp810->node = node;
	sp810->base = of_iomap(node, 0);
	spin_lock_init(&sp810->lock);

	init.name = name;
	init.ops = &clk_sp810_timerclken_ops;
	init.flags = CLK_IS_BASIC;
	init.parent_names = parent_names;
	init.num_parents = ARRAY_SIZE(parent_names);

	for (i = 0; i < ARRAY_SIZE(sp810->timerclken); i++) {
		snprintf(name, ARRAY_SIZE(name), "timerclken%d", i);

		sp810->timerclken[i].sp810 = sp810;
		sp810->timerclken[i].channel = i;
		sp810->timerclken[i].hw.init = &init;

		sp810->timerclken[i].clk = clk_register(NULL,
				&sp810->timerclken[i].hw);
		WARN_ON(IS_ERR(sp810->timerclken[i].clk));
	}

	of_clk_add_provider(node, clk_sp810_timerclken_of_get, sp810);
}
CLK_OF_DECLARE(sp810, "arm,sp810", clk_sp810_of_setup);