1// SPDX-License-Identifier: GPL-2.0-only
  2/*
  3 * Copyright (C) 2016 Rafał Miłecki <rafal@milecki.pl>
  4 */
  5
  6#include <linux/clk-provider.h>
  7#include <linux/err.h>
  8#include <linux/io.h>
  9#include <linux/mfd/syscon.h>
 10#include <linux/of.h>
 11#include <linux/of_address.h>
 12#include <linux/regmap.h>
 13#include <linux/slab.h>
 14
 15#define PMU_XTAL_FREQ_RATIO			0x66c
 16#define  XTAL_ALP_PER_4ILP			0x00001fff
 17#define  XTAL_CTL_EN				0x80000000
 18#define PMU_SLOW_CLK_PERIOD			0x6dc
 19
 20struct bcm53573_ilp {
 21	struct clk_hw hw;
 22	struct regmap *regmap;
 23};
 24
 25static int bcm53573_ilp_enable(struct clk_hw *hw)
 26{
 27	struct bcm53573_ilp *ilp = container_of(hw, struct bcm53573_ilp, hw);
 28
 29	regmap_write(ilp->regmap, PMU_SLOW_CLK_PERIOD, 0x10199);
 30	regmap_write(ilp->regmap, 0x674, 0x10000);
 31
 32	return 0;
 33}
 34
 35static void bcm53573_ilp_disable(struct clk_hw *hw)
 36{
 37	struct bcm53573_ilp *ilp = container_of(hw, struct bcm53573_ilp, hw);
 38
 39	regmap_write(ilp->regmap, PMU_SLOW_CLK_PERIOD, 0);
 40	regmap_write(ilp->regmap, 0x674, 0);
 41}
 42
 43static unsigned long bcm53573_ilp_recalc_rate(struct clk_hw *hw,
 44					      unsigned long parent_rate)
 45{
 46	struct bcm53573_ilp *ilp = container_of(hw, struct bcm53573_ilp, hw);
 47	struct regmap *regmap = ilp->regmap;
 48	u32 last_val, cur_val;
 49	int sum = 0, num = 0, loop_num = 0;
 50	int avg;
 51
 52	/* Enable measurement */
 53	regmap_write(regmap, PMU_XTAL_FREQ_RATIO, XTAL_CTL_EN);
 54
 55	/* Read initial value */
 56	regmap_read(regmap, PMU_XTAL_FREQ_RATIO, &last_val);
 57	last_val &= XTAL_ALP_PER_4ILP;
 58
 59	/*
 60	 * At minimum we should loop for a bit to let hardware do the
 61	 * measurement. This isn't very accurate however, so for a better
 62	 * precision lets try getting 20 different values for and use average.
 63	 */
 64	while (num < 20) {
 65		regmap_read(regmap, PMU_XTAL_FREQ_RATIO, &cur_val);
 66		cur_val &= XTAL_ALP_PER_4ILP;
 67
 68		if (cur_val != last_val) {
 69			/* Got different value, use it */
 70			sum += cur_val;
 71			num++;
 72			loop_num = 0;
 73			last_val = cur_val;
 74		} else if (++loop_num > 5000) {
 75			/* Same value over and over, give up */
 76			sum += cur_val;
 77			num++;
 78			break;
 79		}
 80
 81		cpu_relax();
 82	}
 83
 84	/* Disable measurement to save power */
 85	regmap_write(regmap, PMU_XTAL_FREQ_RATIO, 0x0);
 86
 87	avg = sum / num;
 88
 89	return parent_rate * 4 / avg;
 90}
 91
 92static const struct clk_ops bcm53573_ilp_clk_ops = {
 93	.enable = bcm53573_ilp_enable,
 94	.disable = bcm53573_ilp_disable,
 95	.recalc_rate = bcm53573_ilp_recalc_rate,
 96};
 97
 98static void bcm53573_ilp_init(struct device_node *np)
 99{
100	struct bcm53573_ilp *ilp;
101	struct clk_init_data init = { };
102	const char *parent_name;
103	int err;
104
105	ilp = kzalloc(sizeof(*ilp), GFP_KERNEL);
106	if (!ilp)
107		return;
108
109	parent_name = of_clk_get_parent_name(np, 0);
110	if (!parent_name) {
111		err = -ENOENT;
112		goto err_free_ilp;
113	}
114
115	ilp->regmap = syscon_node_to_regmap(of_get_parent(np));
116	if (IS_ERR(ilp->regmap)) {
117		err = PTR_ERR(ilp->regmap);
118		goto err_free_ilp;
119	}
120
121	init.name = np->name;
122	init.ops = &bcm53573_ilp_clk_ops;
123	init.parent_names = &parent_name;
124	init.num_parents = 1;
125
126	ilp->hw.init = &init;
127	err = clk_hw_register(NULL, &ilp->hw);
128	if (err)
129		goto err_free_ilp;
130
131	err = of_clk_add_hw_provider(np, of_clk_hw_simple_get, &ilp->hw);
132	if (err)
133		goto err_clk_hw_unregister;
134
135	return;
136
137err_clk_hw_unregister:
138	clk_hw_unregister(&ilp->hw);
139err_free_ilp:
140	kfree(ilp);
141	pr_err("Failed to init ILP clock: %d\n", err);
142}
143
144/* We need it very early for arch code, before device model gets ready */
145CLK_OF_DECLARE(bcm53573_ilp_clk, "brcm,bcm53573-ilp", bcm53573_ilp_init);