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_device.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 
30 struct stm32_vrefbuf {
31 	void __iomem *base;
32 	struct clk *clk;
33 	struct device *dev;
34 };
35 
36 static const unsigned int stm32_vrefbuf_voltages[] = {
37 	/* Matches resp. VRS = 000b, 001b, 010b, 011b */
38 	2500000, 2048000, 1800000, 1500000,
39 };
40 
41 static 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 
76 static 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 
96 static 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 
113 static 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 
134 static 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 
153 static 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 
162 static 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 
173 static 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 
226 err_clk_dis:
227 	clk_disable_unprepare(priv->clk);
228 err_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 
236 static int 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 	return 0;
249 };
250 
251 static int __maybe_unused stm32_vrefbuf_runtime_suspend(struct device *dev)
252 {
253 	struct regulator_dev *rdev = dev_get_drvdata(dev);
254 	struct stm32_vrefbuf *priv = rdev_get_drvdata(rdev);
255 
256 	clk_disable_unprepare(priv->clk);
257 
258 	return 0;
259 }
260 
261 static int __maybe_unused stm32_vrefbuf_runtime_resume(struct device *dev)
262 {
263 	struct regulator_dev *rdev = dev_get_drvdata(dev);
264 	struct stm32_vrefbuf *priv = rdev_get_drvdata(rdev);
265 
266 	return clk_prepare_enable(priv->clk);
267 }
268 
269 static const struct dev_pm_ops stm32_vrefbuf_pm_ops = {
270 	SET_SYSTEM_SLEEP_PM_OPS(pm_runtime_force_suspend,
271 				pm_runtime_force_resume)
272 	SET_RUNTIME_PM_OPS(stm32_vrefbuf_runtime_suspend,
273 			   stm32_vrefbuf_runtime_resume,
274 			   NULL)
275 };
276 
277 static const struct of_device_id __maybe_unused stm32_vrefbuf_of_match[] = {
278 	{ .compatible = "st,stm32-vrefbuf", },
279 	{},
280 };
281 MODULE_DEVICE_TABLE(of, stm32_vrefbuf_of_match);
282 
283 static struct platform_driver stm32_vrefbuf_driver = {
284 	.probe = stm32_vrefbuf_probe,
285 	.remove = stm32_vrefbuf_remove,
286 	.driver = {
287 		.name  = "stm32-vrefbuf",
288 		.probe_type = PROBE_PREFER_ASYNCHRONOUS,
289 		.of_match_table = of_match_ptr(stm32_vrefbuf_of_match),
290 		.pm = &stm32_vrefbuf_pm_ops,
291 	},
292 };
293 module_platform_driver(stm32_vrefbuf_driver);
294 
295 MODULE_LICENSE("GPL v2");
296 MODULE_AUTHOR("Fabrice Gasnier <fabrice.gasnier@st.com>");
297 MODULE_DESCRIPTION("STMicroelectronics STM32 VREFBUF driver");
298 MODULE_ALIAS("platform:stm32-vrefbuf");
299