1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Clk driver for NXP LPC18xx/43xx Configuration Registers (CREG)
4 *
5 * Copyright (C) 2015 Joachim Eastwood <manabian@gmail.com>
6 */
7
8#include <linux/clk-provider.h>
9#include <linux/delay.h>
10#include <linux/kernel.h>
11#include <linux/mfd/syscon.h>
12#include <linux/of.h>
13#include <linux/platform_device.h>
14#include <linux/regmap.h>
15
16#define LPC18XX_CREG_CREG0 0x004
17#define LPC18XX_CREG_CREG0_EN1KHZ BIT(0)
18#define LPC18XX_CREG_CREG0_EN32KHZ BIT(1)
19#define LPC18XX_CREG_CREG0_RESET32KHZ BIT(2)
20#define LPC18XX_CREG_CREG0_PD32KHZ BIT(3)
21
22#define to_clk_creg(_hw) container_of(_hw, struct clk_creg_data, hw)
23
24enum {
25 CREG_CLK_1KHZ,
26 CREG_CLK_32KHZ,
27 CREG_CLK_MAX,
28};
29
30struct clk_creg_data {
31 struct clk_hw hw;
32 const char *name;
33 struct regmap *reg;
34 unsigned int en_mask;
35 const struct clk_ops *ops;
36};
37
38#define CREG_CLK(_name, _emask, _ops) \
39{ \
40 .name = _name, \
41 .en_mask = LPC18XX_CREG_CREG0_##_emask, \
42 .ops = &_ops, \
43}
44
45static int clk_creg_32k_prepare(struct clk_hw *hw)
46{
47 struct clk_creg_data *creg = to_clk_creg(hw);
48 int ret;
49
50 ret = regmap_update_bits(map: creg->reg, LPC18XX_CREG_CREG0,
51 LPC18XX_CREG_CREG0_PD32KHZ |
52 LPC18XX_CREG_CREG0_RESET32KHZ, val: 0);
53
54 /*
55 * Powering up the 32k oscillator takes a long while
56 * and sadly there aren't any status bit to poll.
57 */
58 msleep(msecs: 2500);
59
60 return ret;
61}
62
63static void clk_creg_32k_unprepare(struct clk_hw *hw)
64{
65 struct clk_creg_data *creg = to_clk_creg(hw);
66
67 regmap_update_bits(map: creg->reg, LPC18XX_CREG_CREG0,
68 LPC18XX_CREG_CREG0_PD32KHZ,
69 LPC18XX_CREG_CREG0_PD32KHZ);
70}
71
72static int clk_creg_32k_is_prepared(struct clk_hw *hw)
73{
74 struct clk_creg_data *creg = to_clk_creg(hw);
75 u32 reg;
76
77 regmap_read(map: creg->reg, LPC18XX_CREG_CREG0, val: &reg);
78
79 return !(reg & LPC18XX_CREG_CREG0_PD32KHZ) &&
80 !(reg & LPC18XX_CREG_CREG0_RESET32KHZ);
81}
82
83static unsigned long clk_creg_1k_recalc_rate(struct clk_hw *hw,
84 unsigned long parent_rate)
85{
86 return parent_rate / 32;
87}
88
89static int clk_creg_enable(struct clk_hw *hw)
90{
91 struct clk_creg_data *creg = to_clk_creg(hw);
92
93 return regmap_update_bits(map: creg->reg, LPC18XX_CREG_CREG0,
94 mask: creg->en_mask, val: creg->en_mask);
95}
96
97static void clk_creg_disable(struct clk_hw *hw)
98{
99 struct clk_creg_data *creg = to_clk_creg(hw);
100
101 regmap_update_bits(map: creg->reg, LPC18XX_CREG_CREG0,
102 mask: creg->en_mask, val: 0);
103}
104
105static int clk_creg_is_enabled(struct clk_hw *hw)
106{
107 struct clk_creg_data *creg = to_clk_creg(hw);
108 u32 reg;
109
110 regmap_read(map: creg->reg, LPC18XX_CREG_CREG0, val: &reg);
111
112 return !!(reg & creg->en_mask);
113}
114
115static const struct clk_ops clk_creg_32k = {
116 .enable = clk_creg_enable,
117 .disable = clk_creg_disable,
118 .is_enabled = clk_creg_is_enabled,
119 .prepare = clk_creg_32k_prepare,
120 .unprepare = clk_creg_32k_unprepare,
121 .is_prepared = clk_creg_32k_is_prepared,
122};
123
124static const struct clk_ops clk_creg_1k = {
125 .enable = clk_creg_enable,
126 .disable = clk_creg_disable,
127 .is_enabled = clk_creg_is_enabled,
128 .recalc_rate = clk_creg_1k_recalc_rate,
129};
130
131static struct clk_creg_data clk_creg_clocks[] = {
132 [CREG_CLK_1KHZ] = CREG_CLK("1khz_clk", EN1KHZ, clk_creg_1k),
133 [CREG_CLK_32KHZ] = CREG_CLK("32khz_clk", EN32KHZ, clk_creg_32k),
134};
135
136static struct clk *clk_register_creg_clk(struct device *dev,
137 struct clk_creg_data *creg_clk,
138 const char **parent_name,
139 struct regmap *syscon)
140{
141 struct clk_init_data init;
142
143 init.ops = creg_clk->ops;
144 init.name = creg_clk->name;
145 init.parent_names = parent_name;
146 init.num_parents = 1;
147 init.flags = 0;
148
149 creg_clk->reg = syscon;
150 creg_clk->hw.init = &init;
151
152 if (dev)
153 return devm_clk_register(dev, hw: &creg_clk->hw);
154
155 return clk_register(NULL, hw: &creg_clk->hw);
156}
157
158static struct clk *clk_creg_early[CREG_CLK_MAX];
159static struct clk_onecell_data clk_creg_early_data = {
160 .clks = clk_creg_early,
161 .clk_num = CREG_CLK_MAX,
162};
163
164static void __init lpc18xx_creg_clk_init(struct device_node *np)
165{
166 const char *clk_32khz_parent;
167 struct regmap *syscon;
168
169 syscon = syscon_node_to_regmap(np: np->parent);
170 if (IS_ERR(ptr: syscon)) {
171 pr_err("%s: syscon lookup failed\n", __func__);
172 return;
173 }
174
175 clk_32khz_parent = of_clk_get_parent_name(np, index: 0);
176
177 clk_creg_early[CREG_CLK_32KHZ] =
178 clk_register_creg_clk(NULL, creg_clk: &clk_creg_clocks[CREG_CLK_32KHZ],
179 parent_name: &clk_32khz_parent, syscon);
180 clk_creg_early[CREG_CLK_1KHZ] = ERR_PTR(error: -EPROBE_DEFER);
181
182 of_clk_add_provider(np, clk_src_get: of_clk_src_onecell_get, data: &clk_creg_early_data);
183}
184CLK_OF_DECLARE_DRIVER(lpc18xx_creg_clk, "nxp,lpc1850-creg-clk",
185 lpc18xx_creg_clk_init);
186
187static struct clk *clk_creg[CREG_CLK_MAX];
188static struct clk_onecell_data clk_creg_data = {
189 .clks = clk_creg,
190 .clk_num = CREG_CLK_MAX,
191};
192
193static int lpc18xx_creg_clk_probe(struct platform_device *pdev)
194{
195 struct device_node *np = pdev->dev.of_node;
196 struct regmap *syscon;
197
198 syscon = syscon_node_to_regmap(np: np->parent);
199 if (IS_ERR(ptr: syscon)) {
200 dev_err(&pdev->dev, "syscon lookup failed\n");
201 return PTR_ERR(ptr: syscon);
202 }
203
204 clk_creg[CREG_CLK_32KHZ] = clk_creg_early[CREG_CLK_32KHZ];
205 clk_creg[CREG_CLK_1KHZ] =
206 clk_register_creg_clk(NULL, creg_clk: &clk_creg_clocks[CREG_CLK_1KHZ],
207 parent_name: &clk_creg_clocks[CREG_CLK_32KHZ].name,
208 syscon);
209
210 return of_clk_add_provider(np, clk_src_get: of_clk_src_onecell_get, data: &clk_creg_data);
211}
212
213static const struct of_device_id lpc18xx_creg_clk_of_match[] = {
214 { .compatible = "nxp,lpc1850-creg-clk" },
215 {},
216};
217
218static struct platform_driver lpc18xx_creg_clk_driver = {
219 .probe = lpc18xx_creg_clk_probe,
220 .driver = {
221 .name = "lpc18xx-creg-clk",
222 .of_match_table = lpc18xx_creg_clk_of_match,
223 },
224};
225builtin_platform_driver(lpc18xx_creg_clk_driver);
226

source code of linux/drivers/clk/nxp/clk-lpc18xx-creg.c