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
34static 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
45static 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
55static 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 */
80static 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
108static 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
114struct 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