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
31static 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
42static 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
52static 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 */
77static 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
105static 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
111struct 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