1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * Copyright (C) 2012 ST Microelectronics
4 * Viresh Kumar <vireshk@kernel.org>
5 *
6 * General Purpose Timer Synthesizer clock implementation
7 */
8
9 #define pr_fmt(fmt) "clk-gpt-synth: " fmt
10
11 #include <linux/clk-provider.h>
12 #include <linux/slab.h>
13 #include <linux/io.h>
14 #include <linux/err.h>
15 #include "clk.h"
16
17 #define GPT_MSCALE_MASK 0xFFF
18 #define GPT_NSCALE_SHIFT 12
19 #define GPT_NSCALE_MASK 0xF
20
21 /*
22 * DOC: General Purpose Timer Synthesizer clock
23 *
24 * Calculates gpt synth clk rate for different values of mscale and nscale
25 *
26 * Fout= Fin/((2 ^ (N+1)) * (M+1))
27 */
28
29 #define to_clk_gpt(_hw) container_of(_hw, struct clk_gpt, hw)
30
gpt_calc_rate(struct clk_hw * hw,unsigned long prate,int index)31 static unsigned long gpt_calc_rate(struct clk_hw *hw, unsigned long prate,
32 int index)
33 {
34 struct clk_gpt *gpt = to_clk_gpt(hw);
35 struct gpt_rate_tbl *rtbl = gpt->rtbl;
36
37 prate /= ((1 << (rtbl[index].nscale + 1)) * (rtbl[index].mscale + 1));
38
39 return prate;
40 }
41
clk_gpt_round_rate(struct clk_hw * hw,unsigned long drate,unsigned long * prate)42 static long clk_gpt_round_rate(struct clk_hw *hw, unsigned long drate,
43 unsigned long *prate)
44 {
45 struct clk_gpt *gpt = to_clk_gpt(hw);
46 int unused;
47
48 return clk_round_rate_index(hw, drate, *prate, gpt_calc_rate,
49 gpt->rtbl_cnt, &unused);
50 }
51
clk_gpt_recalc_rate(struct clk_hw * hw,unsigned long parent_rate)52 static unsigned long clk_gpt_recalc_rate(struct clk_hw *hw,
53 unsigned long parent_rate)
54 {
55 struct clk_gpt *gpt = to_clk_gpt(hw);
56 unsigned long flags = 0;
57 unsigned int div = 1, val;
58
59 if (gpt->lock)
60 spin_lock_irqsave(gpt->lock, flags);
61
62 val = readl_relaxed(gpt->reg);
63
64 if (gpt->lock)
65 spin_unlock_irqrestore(gpt->lock, flags);
66
67 div += val & GPT_MSCALE_MASK;
68 div *= 1 << (((val >> GPT_NSCALE_SHIFT) & GPT_NSCALE_MASK) + 1);
69
70 if (!div)
71 return 0;
72
73 return parent_rate / div;
74 }
75
76 /* Configures new clock rate of gpt */
clk_gpt_set_rate(struct clk_hw * hw,unsigned long drate,unsigned long prate)77 static int clk_gpt_set_rate(struct clk_hw *hw, unsigned long drate,
78 unsigned long prate)
79 {
80 struct clk_gpt *gpt = to_clk_gpt(hw);
81 struct gpt_rate_tbl *rtbl = gpt->rtbl;
82 unsigned long flags = 0, val;
83 int i;
84
85 clk_round_rate_index(hw, drate, prate, gpt_calc_rate, gpt->rtbl_cnt,
86 &i);
87
88 if (gpt->lock)
89 spin_lock_irqsave(gpt->lock, flags);
90
91 val = readl(gpt->reg) & ~GPT_MSCALE_MASK;
92 val &= ~(GPT_NSCALE_MASK << GPT_NSCALE_SHIFT);
93
94 val |= rtbl[i].mscale & GPT_MSCALE_MASK;
95 val |= (rtbl[i].nscale & GPT_NSCALE_MASK) << GPT_NSCALE_SHIFT;
96
97 writel_relaxed(val, gpt->reg);
98
99 if (gpt->lock)
100 spin_unlock_irqrestore(gpt->lock, flags);
101
102 return 0;
103 }
104
105 static const struct clk_ops clk_gpt_ops = {
106 .recalc_rate = clk_gpt_recalc_rate,
107 .round_rate = clk_gpt_round_rate,
108 .set_rate = clk_gpt_set_rate,
109 };
110
clk_register_gpt(const char * name,const char * parent_name,unsigned long flags,void __iomem * reg,struct gpt_rate_tbl * rtbl,u8 rtbl_cnt,spinlock_t * lock)111 struct clk *clk_register_gpt(const char *name, const char *parent_name, unsigned
112 long flags, void __iomem *reg, struct gpt_rate_tbl *rtbl, u8
113 rtbl_cnt, spinlock_t *lock)
114 {
115 struct clk_init_data init;
116 struct clk_gpt *gpt;
117 struct clk *clk;
118
119 if (!name || !parent_name || !reg || !rtbl || !rtbl_cnt) {
120 pr_err("Invalid arguments passed\n");
121 return ERR_PTR(-EINVAL);
122 }
123
124 gpt = kzalloc(sizeof(*gpt), GFP_KERNEL);
125 if (!gpt)
126 return ERR_PTR(-ENOMEM);
127
128 /* struct clk_gpt assignments */
129 gpt->reg = reg;
130 gpt->rtbl = rtbl;
131 gpt->rtbl_cnt = rtbl_cnt;
132 gpt->lock = lock;
133 gpt->hw.init = &init;
134
135 init.name = name;
136 init.ops = &clk_gpt_ops;
137 init.flags = flags;
138 init.parent_names = &parent_name;
139 init.num_parents = 1;
140
141 clk = clk_register(NULL, &gpt->hw);
142 if (!IS_ERR_OR_NULL(clk))
143 return clk;
144
145 pr_err("clk register failed\n");
146 kfree(gpt);
147
148 return NULL;
149 }
150