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}