1 /*
2 * Copyright (C) 2012 ST Microelectronics
3 * Viresh Kumar <viresh.linux@gmail.com>
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
gpt_calc_rate(struct clk_hw * hw,unsigned long prate,int index)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
clk_gpt_round_rate(struct clk_hw * hw,unsigned long drate,unsigned long * prate)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
clk_gpt_recalc_rate(struct clk_hw * hw,unsigned long parent_rate)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 */
clk_gpt_set_rate(struct clk_hw * hw,unsigned long drate,unsigned long prate)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
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)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 }
155