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(map: ilp->regmap, PMU_SLOW_CLK_PERIOD, val: 0x10199);
30 regmap_write(map: ilp->regmap, reg: 0x674, val: 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(map: ilp->regmap, PMU_SLOW_CLK_PERIOD, val: 0);
40 regmap_write(map: ilp->regmap, reg: 0x674, val: 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(map: regmap, PMU_XTAL_FREQ_RATIO, XTAL_CTL_EN);
54
55 /* Read initial value */
56 regmap_read(map: regmap, PMU_XTAL_FREQ_RATIO, val: &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 let's try getting 20 different values and use average.
63 */
64 while (num < 20) {
65 regmap_read(map: regmap, PMU_XTAL_FREQ_RATIO, val: &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(map: regmap, PMU_XTAL_FREQ_RATIO, val: 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, index: 0);
110 if (!parent_name) {
111 err = -ENOENT;
112 goto err_free_ilp;
113 }
114
115 ilp->regmap = syscon_node_to_regmap(np: np->parent);
116 if (IS_ERR(ptr: ilp->regmap)) {
117 err = PTR_ERR(ptr: 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, hw: &ilp->hw);
128 if (err)
129 goto err_free_ilp;
130
131 err = of_clk_add_hw_provider(np, get: of_clk_hw_simple_get, data: &ilp->hw);
132 if (err)
133 goto err_clk_hw_unregister;
134
135 return;
136
137err_clk_hw_unregister:
138 clk_hw_unregister(hw: &ilp->hw);
139err_free_ilp:
140 kfree(objp: 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);
146

source code of linux/drivers/clk/bcm/clk-bcm53573-ilp.c