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a45896bd VK |
1 | /* |
2 | * Copyright (C) 2012 ST Microelectronics | |
10d8935f | 3 | * Viresh Kumar <viresh.linux@gmail.com> |
a45896bd VK |
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 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"); | |
124 | return ERR_PTR(-EINVAL); | |
125 | } | |
126 | ||
127 | gpt = kzalloc(sizeof(*gpt), GFP_KERNEL); | |
128 | if (!gpt) { | |
129 | pr_err("could not allocate gpt clk\n"); | |
130 | return ERR_PTR(-ENOMEM); | |
131 | } | |
132 | ||
133 | /* struct clk_gpt assignments */ | |
134 | gpt->reg = reg; | |
135 | gpt->rtbl = rtbl; | |
136 | gpt->rtbl_cnt = rtbl_cnt; | |
137 | gpt->lock = lock; | |
138 | gpt->hw.init = &init; | |
139 | ||
140 | init.name = name; | |
141 | init.ops = &clk_gpt_ops; | |
142 | init.flags = flags; | |
143 | init.parent_names = &parent_name; | |
144 | init.num_parents = 1; | |
145 | ||
146 | clk = clk_register(NULL, &gpt->hw); | |
147 | if (!IS_ERR_OR_NULL(clk)) | |
148 | return clk; | |
149 | ||
150 | pr_err("clk register failed\n"); | |
151 | kfree(gpt); | |
152 | ||
153 | return NULL; | |
154 | } |