1 /*
2  * Copyright (C) 2012 ST Microelectronics
3  * Viresh Kumar <vireshk@kernel.org>
4  *
5  * This file is licensed under the terms of the GNU General Public
6  * License version 2. This program is licensed "as is" without any
7  * warranty of any kind, whether express or implied.
8  *
9  * General Purpose Timer Synthesizer clock implementation
10  */
11 
12 #define pr_fmt(fmt) "clk-gpt-synth: " fmt
13 
14 #include <linux/clk-provider.h>
15 #include <linux/slab.h>
16 #include <linux/io.h>
17 #include <linux/err.h>
18 #include "clk.h"
19 
20 #define GPT_MSCALE_MASK		0xFFF
21 #define GPT_NSCALE_SHIFT	12
22 #define GPT_NSCALE_MASK		0xF
23 
24 /*
25  * DOC: General Purpose Timer Synthesizer clock
26  *
27  * Calculates gpt synth clk rate for different values of mscale and nscale
28  *
29  * Fout= Fin/((2 ^ (N+1)) * (M+1))
30  */
31 
32 #define to_clk_gpt(_hw) container_of(_hw, struct clk_gpt, hw)
33 
34 static unsigned long gpt_calc_rate(struct clk_hw *hw, unsigned long prate,
35 		int index)
36 {
37 	struct clk_gpt *gpt = to_clk_gpt(hw);
38 	struct gpt_rate_tbl *rtbl = gpt->rtbl;
39 
40 	prate /= ((1 << (rtbl[index].nscale + 1)) * (rtbl[index].mscale + 1));
41 
42 	return prate;
43 }
44 
45 static long clk_gpt_round_rate(struct clk_hw *hw, unsigned long drate,
46 		unsigned long *prate)
47 {
48 	struct clk_gpt *gpt = to_clk_gpt(hw);
49 	int unused;
50 
51 	return clk_round_rate_index(hw, drate, *prate, gpt_calc_rate,
52 			gpt->rtbl_cnt, &unused);
53 }
54 
55 static unsigned long clk_gpt_recalc_rate(struct clk_hw *hw,
56 		unsigned long parent_rate)
57 {
58 	struct clk_gpt *gpt = to_clk_gpt(hw);
59 	unsigned long flags = 0;
60 	unsigned int div = 1, val;
61 
62 	if (gpt->lock)
63 		spin_lock_irqsave(gpt->lock, flags);
64 
65 	val = readl_relaxed(gpt->reg);
66 
67 	if (gpt->lock)
68 		spin_unlock_irqrestore(gpt->lock, flags);
69 
70 	div += val & GPT_MSCALE_MASK;
71 	div *= 1 << (((val >> GPT_NSCALE_SHIFT) & GPT_NSCALE_MASK) + 1);
72 
73 	if (!div)
74 		return 0;
75 
76 	return parent_rate / div;
77 }
78 
79 /* Configures new clock rate of gpt */
80 static int clk_gpt_set_rate(struct clk_hw *hw, unsigned long drate,
81 				unsigned long prate)
82 {
83 	struct clk_gpt *gpt = to_clk_gpt(hw);
84 	struct gpt_rate_tbl *rtbl = gpt->rtbl;
85 	unsigned long flags = 0, val;
86 	int i;
87 
88 	clk_round_rate_index(hw, drate, prate, gpt_calc_rate, gpt->rtbl_cnt,
89 			&i);
90 
91 	if (gpt->lock)
92 		spin_lock_irqsave(gpt->lock, flags);
93 
94 	val = readl(gpt->reg) & ~GPT_MSCALE_MASK;
95 	val &= ~(GPT_NSCALE_MASK << GPT_NSCALE_SHIFT);
96 
97 	val |= rtbl[i].mscale & GPT_MSCALE_MASK;
98 	val |= (rtbl[i].nscale & GPT_NSCALE_MASK) << GPT_NSCALE_SHIFT;
99 
100 	writel_relaxed(val, gpt->reg);
101 
102 	if (gpt->lock)
103 		spin_unlock_irqrestore(gpt->lock, flags);
104 
105 	return 0;
106 }
107 
108 static const struct clk_ops clk_gpt_ops = {
109 	.recalc_rate = clk_gpt_recalc_rate,
110 	.round_rate = clk_gpt_round_rate,
111 	.set_rate = clk_gpt_set_rate,
112 };
113 
114 struct clk *clk_register_gpt(const char *name, const char *parent_name, unsigned
115 		long flags, void __iomem *reg, struct gpt_rate_tbl *rtbl, u8
116 		rtbl_cnt, spinlock_t *lock)
117 {
118 	struct clk_init_data init;
119 	struct clk_gpt *gpt;
120 	struct clk *clk;
121 
122 	if (!name || !parent_name || !reg || !rtbl || !rtbl_cnt) {
123 		pr_err("Invalid arguments passed\n");
124 		return ERR_PTR(-EINVAL);
125 	}
126 
127 	gpt = kzalloc(sizeof(*gpt), GFP_KERNEL);
128 	if (!gpt)
129 		return ERR_PTR(-ENOMEM);
130 
131 	/* struct clk_gpt assignments */
132 	gpt->reg = reg;
133 	gpt->rtbl = rtbl;
134 	gpt->rtbl_cnt = rtbl_cnt;
135 	gpt->lock = lock;
136 	gpt->hw.init = &init;
137 
138 	init.name = name;
139 	init.ops = &clk_gpt_ops;
140 	init.flags = flags;
141 	init.parent_names = &parent_name;
142 	init.num_parents = 1;
143 
144 	clk = clk_register(NULL, &gpt->hw);
145 	if (!IS_ERR_OR_NULL(clk))
146 		return clk;
147 
148 	pr_err("clk register failed\n");
149 	kfree(gpt);
150 
151 	return NULL;
152 }
153