1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Copyright (C) STMicroelectronics 2017
4 *
5 * Author: Fabrice Gasnier <fabrice.gasnier@st.com>
6 */
7
8#include <linux/bitfield.h>
9#include <linux/clk.h>
10#include <linux/io.h>
11#include <linux/iopoll.h>
12#include <linux/module.h>
13#include <linux/of.h>
14#include <linux/platform_device.h>
15#include <linux/regulator/driver.h>
16#include <linux/regulator/of_regulator.h>
17#include <linux/pm_runtime.h>
18
19/* STM32 VREFBUF registers */
20#define STM32_VREFBUF_CSR		0x00
21
22/* STM32 VREFBUF CSR bitfields */
23#define STM32_VRS			GENMASK(6, 4)
24#define STM32_VRR			BIT(3)
25#define STM32_HIZ			BIT(1)
26#define STM32_ENVR			BIT(0)
27
28#define STM32_VREFBUF_AUTO_SUSPEND_DELAY_MS	10
29
30struct stm32_vrefbuf {
31	void __iomem *base;
32	struct clk *clk;
33	struct device *dev;
34};
35
36static const unsigned int stm32_vrefbuf_voltages[] = {
37	/* Matches resp. VRS = 000b, 001b, 010b, 011b */
38	2500000, 2048000, 1800000, 1500000,
39};
40
41static int stm32_vrefbuf_enable(struct regulator_dev *rdev)
42{
43	struct stm32_vrefbuf *priv = rdev_get_drvdata(rdev);
44	u32 val;
45	int ret;
46
47	ret = pm_runtime_resume_and_get(priv->dev);
48	if (ret < 0)
49		return ret;
50
51	val = readl_relaxed(priv->base + STM32_VREFBUF_CSR);
52	val = (val & ~STM32_HIZ) | STM32_ENVR;
53	writel_relaxed(val, priv->base + STM32_VREFBUF_CSR);
54
55	/*
56	 * Vrefbuf startup time depends on external capacitor: wait here for
57	 * VRR to be set. That means output has reached expected value.
58	 * ~650us sleep should be enough for caps up to 1.5uF. Use 10ms as
59	 * arbitrary timeout.
60	 */
61	ret = readl_poll_timeout(priv->base + STM32_VREFBUF_CSR, val,
62				 val & STM32_VRR, 650, 10000);
63	if (ret) {
64		dev_err(&rdev->dev, "stm32 vrefbuf timed out!\n");
65		val = readl_relaxed(priv->base + STM32_VREFBUF_CSR);
66		val = (val & ~STM32_ENVR) | STM32_HIZ;
67		writel_relaxed(val, priv->base + STM32_VREFBUF_CSR);
68	}
69
70	pm_runtime_mark_last_busy(priv->dev);
71	pm_runtime_put_autosuspend(priv->dev);
72
73	return ret;
74}
75
76static int stm32_vrefbuf_disable(struct regulator_dev *rdev)
77{
78	struct stm32_vrefbuf *priv = rdev_get_drvdata(rdev);
79	u32 val;
80	int ret;
81
82	ret = pm_runtime_resume_and_get(priv->dev);
83	if (ret < 0)
84		return ret;
85
86	val = readl_relaxed(priv->base + STM32_VREFBUF_CSR);
87	val &= ~STM32_ENVR;
88	writel_relaxed(val, priv->base + STM32_VREFBUF_CSR);
89
90	pm_runtime_mark_last_busy(priv->dev);
91	pm_runtime_put_autosuspend(priv->dev);
92
93	return 0;
94}
95
96static int stm32_vrefbuf_is_enabled(struct regulator_dev *rdev)
97{
98	struct stm32_vrefbuf *priv = rdev_get_drvdata(rdev);
99	int ret;
100
101	ret = pm_runtime_resume_and_get(priv->dev);
102	if (ret < 0)
103		return ret;
104
105	ret = readl_relaxed(priv->base + STM32_VREFBUF_CSR) & STM32_ENVR;
106
107	pm_runtime_mark_last_busy(priv->dev);
108	pm_runtime_put_autosuspend(priv->dev);
109
110	return ret;
111}
112
113static int stm32_vrefbuf_set_voltage_sel(struct regulator_dev *rdev,
114					 unsigned sel)
115{
116	struct stm32_vrefbuf *priv = rdev_get_drvdata(rdev);
117	u32 val;
118	int ret;
119
120	ret = pm_runtime_resume_and_get(priv->dev);
121	if (ret < 0)
122		return ret;
123
124	val = readl_relaxed(priv->base + STM32_VREFBUF_CSR);
125	val = (val & ~STM32_VRS) | FIELD_PREP(STM32_VRS, sel);
126	writel_relaxed(val, priv->base + STM32_VREFBUF_CSR);
127
128	pm_runtime_mark_last_busy(priv->dev);
129	pm_runtime_put_autosuspend(priv->dev);
130
131	return 0;
132}
133
134static int stm32_vrefbuf_get_voltage_sel(struct regulator_dev *rdev)
135{
136	struct stm32_vrefbuf *priv = rdev_get_drvdata(rdev);
137	u32 val;
138	int ret;
139
140	ret = pm_runtime_resume_and_get(priv->dev);
141	if (ret < 0)
142		return ret;
143
144	val = readl_relaxed(priv->base + STM32_VREFBUF_CSR);
145	ret = FIELD_GET(STM32_VRS, val);
146
147	pm_runtime_mark_last_busy(priv->dev);
148	pm_runtime_put_autosuspend(priv->dev);
149
150	return ret;
151}
152
153static const struct regulator_ops stm32_vrefbuf_volt_ops = {
154	.enable		= stm32_vrefbuf_enable,
155	.disable	= stm32_vrefbuf_disable,
156	.is_enabled	= stm32_vrefbuf_is_enabled,
157	.get_voltage_sel = stm32_vrefbuf_get_voltage_sel,
158	.set_voltage_sel = stm32_vrefbuf_set_voltage_sel,
159	.list_voltage	= regulator_list_voltage_table,
160};
161
162static const struct regulator_desc stm32_vrefbuf_regu = {
163	.name = "vref",
164	.supply_name = "vdda",
165	.volt_table = stm32_vrefbuf_voltages,
166	.n_voltages = ARRAY_SIZE(stm32_vrefbuf_voltages),
167	.ops = &stm32_vrefbuf_volt_ops,
168	.off_on_delay = 1000,
169	.type = REGULATOR_VOLTAGE,
170	.owner = THIS_MODULE,
171};
172
173static int stm32_vrefbuf_probe(struct platform_device *pdev)
174{
175	struct stm32_vrefbuf *priv;
176	struct regulator_config config = { };
177	struct regulator_dev *rdev;
178	int ret;
179
180	priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
181	if (!priv)
182		return -ENOMEM;
183	priv->dev = &pdev->dev;
184
185	priv->base = devm_platform_ioremap_resource(pdev, 0);
186	if (IS_ERR(priv->base))
187		return PTR_ERR(priv->base);
188
189	priv->clk = devm_clk_get(&pdev->dev, NULL);
190	if (IS_ERR(priv->clk))
191		return PTR_ERR(priv->clk);
192
193	pm_runtime_get_noresume(&pdev->dev);
194	pm_runtime_set_active(&pdev->dev);
195	pm_runtime_set_autosuspend_delay(&pdev->dev,
196					 STM32_VREFBUF_AUTO_SUSPEND_DELAY_MS);
197	pm_runtime_use_autosuspend(&pdev->dev);
198	pm_runtime_enable(&pdev->dev);
199
200	ret = clk_prepare_enable(priv->clk);
201	if (ret) {
202		dev_err(&pdev->dev, "clk prepare failed with error %d\n", ret);
203		goto err_pm_stop;
204	}
205
206	config.dev = &pdev->dev;
207	config.driver_data = priv;
208	config.of_node = pdev->dev.of_node;
209	config.init_data = of_get_regulator_init_data(&pdev->dev,
210						      pdev->dev.of_node,
211						      &stm32_vrefbuf_regu);
212
213	rdev = regulator_register(&pdev->dev, &stm32_vrefbuf_regu, &config);
214	if (IS_ERR(rdev)) {
215		ret = PTR_ERR(rdev);
216		dev_err(&pdev->dev, "register failed with error %d\n", ret);
217		goto err_clk_dis;
218	}
219	platform_set_drvdata(pdev, rdev);
220
221	pm_runtime_mark_last_busy(&pdev->dev);
222	pm_runtime_put_autosuspend(&pdev->dev);
223
224	return 0;
225
226err_clk_dis:
227	clk_disable_unprepare(priv->clk);
228err_pm_stop:
229	pm_runtime_disable(&pdev->dev);
230	pm_runtime_set_suspended(&pdev->dev);
231	pm_runtime_put_noidle(&pdev->dev);
232
233	return ret;
234}
235
236static void stm32_vrefbuf_remove(struct platform_device *pdev)
237{
238	struct regulator_dev *rdev = platform_get_drvdata(pdev);
239	struct stm32_vrefbuf *priv = rdev_get_drvdata(rdev);
240
241	pm_runtime_get_sync(&pdev->dev);
242	regulator_unregister(rdev);
243	clk_disable_unprepare(priv->clk);
244	pm_runtime_disable(&pdev->dev);
245	pm_runtime_set_suspended(&pdev->dev);
246	pm_runtime_put_noidle(&pdev->dev);
247};
248
249static int __maybe_unused stm32_vrefbuf_runtime_suspend(struct device *dev)
250{
251	struct regulator_dev *rdev = dev_get_drvdata(dev);
252	struct stm32_vrefbuf *priv = rdev_get_drvdata(rdev);
253
254	clk_disable_unprepare(priv->clk);
255
256	return 0;
257}
258
259static int __maybe_unused stm32_vrefbuf_runtime_resume(struct device *dev)
260{
261	struct regulator_dev *rdev = dev_get_drvdata(dev);
262	struct stm32_vrefbuf *priv = rdev_get_drvdata(rdev);
263
264	return clk_prepare_enable(priv->clk);
265}
266
267static const struct dev_pm_ops stm32_vrefbuf_pm_ops = {
268	SET_SYSTEM_SLEEP_PM_OPS(pm_runtime_force_suspend,
269				pm_runtime_force_resume)
270	SET_RUNTIME_PM_OPS(stm32_vrefbuf_runtime_suspend,
271			   stm32_vrefbuf_runtime_resume,
272			   NULL)
273};
274
275static const struct of_device_id __maybe_unused stm32_vrefbuf_of_match[] = {
276	{ .compatible = "st,stm32-vrefbuf", },
277	{},
278};
279MODULE_DEVICE_TABLE(of, stm32_vrefbuf_of_match);
280
281static struct platform_driver stm32_vrefbuf_driver = {
282	.probe = stm32_vrefbuf_probe,
283	.remove_new = stm32_vrefbuf_remove,
284	.driver = {
285		.name  = "stm32-vrefbuf",
286		.probe_type = PROBE_PREFER_ASYNCHRONOUS,
287		.of_match_table = of_match_ptr(stm32_vrefbuf_of_match),
288		.pm = &stm32_vrefbuf_pm_ops,
289	},
290};
291module_platform_driver(stm32_vrefbuf_driver);
292
293MODULE_LICENSE("GPL v2");
294MODULE_AUTHOR("Fabrice Gasnier <fabrice.gasnier@st.com>");
295MODULE_DESCRIPTION("STMicroelectronics STM32 VREFBUF driver");
296MODULE_ALIAS("platform:stm32-vrefbuf");
297