1/*
2 * This program is free software; you can redistribute it and/or modify
3 * it under the terms of the GNU General Public License version 2 as
4 * published by the Free Software Foundation.
5 *
6 * This program is distributed in the hope that it will be useful,
7 * but WITHOUT ANY WARRANTY; without even the implied warranty of
8 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
9 * GNU General Public License for more details.
10 *
11 * Copyright (C) 2013 ARM Limited
12 */
13
14#include <linux/amba/sp810.h>
15#include <linux/clkdev.h>
16#include <linux/clk-provider.h>
17#include <linux/err.h>
18#include <linux/of.h>
19#include <linux/of_address.h>
20
21#define to_clk_sp810_timerclken(_hw) \
22		container_of(_hw, struct clk_sp810_timerclken, hw)
23
24struct clk_sp810;
25
26struct clk_sp810_timerclken {
27	struct clk_hw hw;
28	struct clk *clk;
29	struct clk_sp810 *sp810;
30	int channel;
31};
32
33struct clk_sp810 {
34	struct device_node *node;
35	int refclk_index, timclk_index;
36	void __iomem *base;
37	spinlock_t lock;
38	struct clk_sp810_timerclken timerclken[4];
39	struct clk *refclk;
40	struct clk *timclk;
41};
42
43static u8 clk_sp810_timerclken_get_parent(struct clk_hw *hw)
44{
45	struct clk_sp810_timerclken *timerclken = to_clk_sp810_timerclken(hw);
46	u32 val = readl(timerclken->sp810->base + SCCTRL);
47
48	return !!(val & (1 << SCCTRL_TIMERENnSEL_SHIFT(timerclken->channel)));
49}
50
51static int clk_sp810_timerclken_set_parent(struct clk_hw *hw, u8 index)
52{
53	struct clk_sp810_timerclken *timerclken = to_clk_sp810_timerclken(hw);
54	struct clk_sp810 *sp810 = timerclken->sp810;
55	u32 val, shift = SCCTRL_TIMERENnSEL_SHIFT(timerclken->channel);
56	unsigned long flags = 0;
57
58	if (WARN_ON(index > 1))
59		return -EINVAL;
60
61	spin_lock_irqsave(&sp810->lock, flags);
62
63	val = readl(sp810->base + SCCTRL);
64	val &= ~(1 << shift);
65	val |= index << shift;
66	writel(val, sp810->base + SCCTRL);
67
68	spin_unlock_irqrestore(&sp810->lock, flags);
69
70	return 0;
71}
72
73/*
74 * FIXME - setting the parent every time .prepare is invoked is inefficient.
75 * This is better handled by a dedicated clock tree configuration mechanism at
76 * init-time.  Revisit this later when such a mechanism exists
77 */
78static int clk_sp810_timerclken_prepare(struct clk_hw *hw)
79{
80	struct clk_sp810_timerclken *timerclken = to_clk_sp810_timerclken(hw);
81	struct clk_sp810 *sp810 = timerclken->sp810;
82	struct clk *old_parent = __clk_get_parent(hw->clk);
83	struct clk *new_parent;
84
85	if (!sp810->refclk)
86		sp810->refclk = of_clk_get(sp810->node, sp810->refclk_index);
87
88	if (!sp810->timclk)
89		sp810->timclk = of_clk_get(sp810->node, sp810->timclk_index);
90
91	if (WARN_ON(IS_ERR(sp810->refclk) || IS_ERR(sp810->timclk)))
92		return -ENOENT;
93
94	/* Select fastest parent */
95	if (clk_get_rate(sp810->refclk) > clk_get_rate(sp810->timclk))
96		new_parent = sp810->refclk;
97	else
98		new_parent = sp810->timclk;
99
100	/* Switch the parent if necessary */
101	if (old_parent != new_parent) {
102		clk_prepare(new_parent);
103		clk_set_parent(hw->clk, new_parent);
104		clk_unprepare(old_parent);
105	}
106
107	return 0;
108}
109
110static void clk_sp810_timerclken_unprepare(struct clk_hw *hw)
111{
112	struct clk_sp810_timerclken *timerclken = to_clk_sp810_timerclken(hw);
113	struct clk_sp810 *sp810 = timerclken->sp810;
114
115	clk_put(sp810->timclk);
116	clk_put(sp810->refclk);
117}
118
119static const struct clk_ops clk_sp810_timerclken_ops = {
120	.prepare = clk_sp810_timerclken_prepare,
121	.unprepare = clk_sp810_timerclken_unprepare,
122	.get_parent = clk_sp810_timerclken_get_parent,
123	.set_parent = clk_sp810_timerclken_set_parent,
124};
125
126static struct clk *clk_sp810_timerclken_of_get(struct of_phandle_args *clkspec,
127		void *data)
128{
129	struct clk_sp810 *sp810 = data;
130
131	if (WARN_ON(clkspec->args_count != 1 || clkspec->args[0] >
132			ARRAY_SIZE(sp810->timerclken)))
133		return NULL;
134
135	return sp810->timerclken[clkspec->args[0]].clk;
136}
137
138void __init clk_sp810_of_setup(struct device_node *node)
139{
140	struct clk_sp810 *sp810 = kzalloc(sizeof(*sp810), GFP_KERNEL);
141	const char *parent_names[2];
142	char name[12];
143	struct clk_init_data init;
144	int i;
145
146	if (!sp810) {
147		pr_err("Failed to allocate memory for SP810!\n");
148		return;
149	}
150
151	sp810->refclk_index = of_property_match_string(node, "clock-names",
152			"refclk");
153	parent_names[0] = of_clk_get_parent_name(node, sp810->refclk_index);
154
155	sp810->timclk_index = of_property_match_string(node, "clock-names",
156			"timclk");
157	parent_names[1] = of_clk_get_parent_name(node, sp810->timclk_index);
158
159	if (parent_names[0] <= 0 || parent_names[1] <= 0) {
160		pr_warn("Failed to obtain parent clocks for SP810!\n");
161		return;
162	}
163
164	sp810->node = node;
165	sp810->base = of_iomap(node, 0);
166	spin_lock_init(&sp810->lock);
167
168	init.name = name;
169	init.ops = &clk_sp810_timerclken_ops;
170	init.flags = CLK_IS_BASIC;
171	init.parent_names = parent_names;
172	init.num_parents = ARRAY_SIZE(parent_names);
173
174	for (i = 0; i < ARRAY_SIZE(sp810->timerclken); i++) {
175		snprintf(name, ARRAY_SIZE(name), "timerclken%d", i);
176
177		sp810->timerclken[i].sp810 = sp810;
178		sp810->timerclken[i].channel = i;
179		sp810->timerclken[i].hw.init = &init;
180
181		sp810->timerclken[i].clk = clk_register(NULL,
182				&sp810->timerclken[i].hw);
183		WARN_ON(IS_ERR(sp810->timerclken[i].clk));
184	}
185
186	of_clk_add_provider(node, clk_sp810_timerclken_of_get, sp810);
187}
188CLK_OF_DECLARE(sp810, "arm,sp810", clk_sp810_of_setup);
189