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 
24 struct clk_sp810;
25 
26 struct clk_sp810_timerclken {
27 	struct clk_hw hw;
28 	struct clk *clk;
29 	struct clk_sp810 *sp810;
30 	int channel;
31 };
32 
33 struct 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 
43 static 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 
51 static 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  */
78 static 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 
110 static 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 
119 static 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 
126 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 
138 void __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 }
188 CLK_OF_DECLARE(sp810, "arm,sp810", clk_sp810_of_setup);
189