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 
stm32_vrefbuf_enable(struct regulator_dev * rdev)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_get_sync(priv->dev);
48 	if (ret < 0) {
49 		pm_runtime_put_noidle(priv->dev);
50 		return ret;
51 	}
52 
53 	val = readl_relaxed(priv->base + STM32_VREFBUF_CSR);
54 	val = (val & ~STM32_HIZ) | STM32_ENVR;
55 	writel_relaxed(val, priv->base + STM32_VREFBUF_CSR);
56 
57 	/*
58 	 * Vrefbuf startup time depends on external capacitor: wait here for
59 	 * VRR to be set. That means output has reached expected value.
60 	 * ~650us sleep should be enough for caps up to 1.5uF. Use 10ms as
61 	 * arbitrary timeout.
62 	 */
63 	ret = readl_poll_timeout(priv->base + STM32_VREFBUF_CSR, val,
64 				 val & STM32_VRR, 650, 10000);
65 	if (ret) {
66 		dev_err(&rdev->dev, "stm32 vrefbuf timed out!\n");
67 		val = readl_relaxed(priv->base + STM32_VREFBUF_CSR);
68 		val = (val & ~STM32_ENVR) | STM32_HIZ;
69 		writel_relaxed(val, priv->base + STM32_VREFBUF_CSR);
70 	}
71 
72 	pm_runtime_mark_last_busy(priv->dev);
73 	pm_runtime_put_autosuspend(priv->dev);
74 
75 	return ret;
76 }
77 
stm32_vrefbuf_disable(struct regulator_dev * rdev)78 static int stm32_vrefbuf_disable(struct regulator_dev *rdev)
79 {
80 	struct stm32_vrefbuf *priv = rdev_get_drvdata(rdev);
81 	u32 val;
82 	int ret;
83 
84 	ret = pm_runtime_get_sync(priv->dev);
85 	if (ret < 0) {
86 		pm_runtime_put_noidle(priv->dev);
87 		return ret;
88 	}
89 
90 	val = readl_relaxed(priv->base + STM32_VREFBUF_CSR);
91 	val &= ~STM32_ENVR;
92 	writel_relaxed(val, priv->base + STM32_VREFBUF_CSR);
93 
94 	pm_runtime_mark_last_busy(priv->dev);
95 	pm_runtime_put_autosuspend(priv->dev);
96 
97 	return 0;
98 }
99 
stm32_vrefbuf_is_enabled(struct regulator_dev * rdev)100 static int stm32_vrefbuf_is_enabled(struct regulator_dev *rdev)
101 {
102 	struct stm32_vrefbuf *priv = rdev_get_drvdata(rdev);
103 	int ret;
104 
105 	ret = pm_runtime_get_sync(priv->dev);
106 	if (ret < 0) {
107 		pm_runtime_put_noidle(priv->dev);
108 		return ret;
109 	}
110 
111 	ret = readl_relaxed(priv->base + STM32_VREFBUF_CSR) & STM32_ENVR;
112 
113 	pm_runtime_mark_last_busy(priv->dev);
114 	pm_runtime_put_autosuspend(priv->dev);
115 
116 	return ret;
117 }
118 
stm32_vrefbuf_set_voltage_sel(struct regulator_dev * rdev,unsigned sel)119 static int stm32_vrefbuf_set_voltage_sel(struct regulator_dev *rdev,
120 					 unsigned sel)
121 {
122 	struct stm32_vrefbuf *priv = rdev_get_drvdata(rdev);
123 	u32 val;
124 	int ret;
125 
126 	ret = pm_runtime_get_sync(priv->dev);
127 	if (ret < 0) {
128 		pm_runtime_put_noidle(priv->dev);
129 		return ret;
130 	}
131 
132 	val = readl_relaxed(priv->base + STM32_VREFBUF_CSR);
133 	val = (val & ~STM32_VRS) | FIELD_PREP(STM32_VRS, sel);
134 	writel_relaxed(val, priv->base + STM32_VREFBUF_CSR);
135 
136 	pm_runtime_mark_last_busy(priv->dev);
137 	pm_runtime_put_autosuspend(priv->dev);
138 
139 	return 0;
140 }
141 
stm32_vrefbuf_get_voltage_sel(struct regulator_dev * rdev)142 static int stm32_vrefbuf_get_voltage_sel(struct regulator_dev *rdev)
143 {
144 	struct stm32_vrefbuf *priv = rdev_get_drvdata(rdev);
145 	u32 val;
146 	int ret;
147 
148 	ret = pm_runtime_get_sync(priv->dev);
149 	if (ret < 0) {
150 		pm_runtime_put_noidle(priv->dev);
151 		return ret;
152 	}
153 
154 	val = readl_relaxed(priv->base + STM32_VREFBUF_CSR);
155 	ret = FIELD_GET(STM32_VRS, val);
156 
157 	pm_runtime_mark_last_busy(priv->dev);
158 	pm_runtime_put_autosuspend(priv->dev);
159 
160 	return ret;
161 }
162 
163 static const struct regulator_ops stm32_vrefbuf_volt_ops = {
164 	.enable		= stm32_vrefbuf_enable,
165 	.disable	= stm32_vrefbuf_disable,
166 	.is_enabled	= stm32_vrefbuf_is_enabled,
167 	.get_voltage_sel = stm32_vrefbuf_get_voltage_sel,
168 	.set_voltage_sel = stm32_vrefbuf_set_voltage_sel,
169 	.list_voltage	= regulator_list_voltage_table,
170 };
171 
172 static const struct regulator_desc stm32_vrefbuf_regu = {
173 	.name = "vref",
174 	.supply_name = "vdda",
175 	.volt_table = stm32_vrefbuf_voltages,
176 	.n_voltages = ARRAY_SIZE(stm32_vrefbuf_voltages),
177 	.ops = &stm32_vrefbuf_volt_ops,
178 	.off_on_delay = 1000,
179 	.type = REGULATOR_VOLTAGE,
180 	.owner = THIS_MODULE,
181 };
182 
stm32_vrefbuf_probe(struct platform_device * pdev)183 static int stm32_vrefbuf_probe(struct platform_device *pdev)
184 {
185 	struct stm32_vrefbuf *priv;
186 	struct regulator_config config = { };
187 	struct regulator_dev *rdev;
188 	int ret;
189 
190 	priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
191 	if (!priv)
192 		return -ENOMEM;
193 	priv->dev = &pdev->dev;
194 
195 	priv->base = devm_platform_ioremap_resource(pdev, 0);
196 	if (IS_ERR(priv->base))
197 		return PTR_ERR(priv->base);
198 
199 	priv->clk = devm_clk_get(&pdev->dev, NULL);
200 	if (IS_ERR(priv->clk))
201 		return PTR_ERR(priv->clk);
202 
203 	pm_runtime_get_noresume(&pdev->dev);
204 	pm_runtime_set_active(&pdev->dev);
205 	pm_runtime_set_autosuspend_delay(&pdev->dev,
206 					 STM32_VREFBUF_AUTO_SUSPEND_DELAY_MS);
207 	pm_runtime_use_autosuspend(&pdev->dev);
208 	pm_runtime_enable(&pdev->dev);
209 
210 	ret = clk_prepare_enable(priv->clk);
211 	if (ret) {
212 		dev_err(&pdev->dev, "clk prepare failed with error %d\n", ret);
213 		goto err_pm_stop;
214 	}
215 
216 	config.dev = &pdev->dev;
217 	config.driver_data = priv;
218 	config.of_node = pdev->dev.of_node;
219 	config.init_data = of_get_regulator_init_data(&pdev->dev,
220 						      pdev->dev.of_node,
221 						      &stm32_vrefbuf_regu);
222 
223 	rdev = regulator_register(&stm32_vrefbuf_regu, &config);
224 	if (IS_ERR(rdev)) {
225 		ret = PTR_ERR(rdev);
226 		dev_err(&pdev->dev, "register failed with error %d\n", ret);
227 		goto err_clk_dis;
228 	}
229 	platform_set_drvdata(pdev, rdev);
230 
231 	pm_runtime_mark_last_busy(&pdev->dev);
232 	pm_runtime_put_autosuspend(&pdev->dev);
233 
234 	return 0;
235 
236 err_clk_dis:
237 	clk_disable_unprepare(priv->clk);
238 err_pm_stop:
239 	pm_runtime_disable(&pdev->dev);
240 	pm_runtime_set_suspended(&pdev->dev);
241 	pm_runtime_put_noidle(&pdev->dev);
242 
243 	return ret;
244 }
245 
stm32_vrefbuf_remove(struct platform_device * pdev)246 static int stm32_vrefbuf_remove(struct platform_device *pdev)
247 {
248 	struct regulator_dev *rdev = platform_get_drvdata(pdev);
249 	struct stm32_vrefbuf *priv = rdev_get_drvdata(rdev);
250 
251 	pm_runtime_get_sync(&pdev->dev);
252 	regulator_unregister(rdev);
253 	clk_disable_unprepare(priv->clk);
254 	pm_runtime_disable(&pdev->dev);
255 	pm_runtime_set_suspended(&pdev->dev);
256 	pm_runtime_put_noidle(&pdev->dev);
257 
258 	return 0;
259 };
260 
stm32_vrefbuf_runtime_suspend(struct device * dev)261 static int __maybe_unused stm32_vrefbuf_runtime_suspend(struct device *dev)
262 {
263 	struct regulator_dev *rdev = dev_get_drvdata(dev);
264 	struct stm32_vrefbuf *priv = rdev_get_drvdata(rdev);
265 
266 	clk_disable_unprepare(priv->clk);
267 
268 	return 0;
269 }
270 
stm32_vrefbuf_runtime_resume(struct device * dev)271 static int __maybe_unused stm32_vrefbuf_runtime_resume(struct device *dev)
272 {
273 	struct regulator_dev *rdev = dev_get_drvdata(dev);
274 	struct stm32_vrefbuf *priv = rdev_get_drvdata(rdev);
275 
276 	return clk_prepare_enable(priv->clk);
277 }
278 
279 static const struct dev_pm_ops stm32_vrefbuf_pm_ops = {
280 	SET_SYSTEM_SLEEP_PM_OPS(pm_runtime_force_suspend,
281 				pm_runtime_force_resume)
282 	SET_RUNTIME_PM_OPS(stm32_vrefbuf_runtime_suspend,
283 			   stm32_vrefbuf_runtime_resume,
284 			   NULL)
285 };
286 
287 static const struct of_device_id __maybe_unused stm32_vrefbuf_of_match[] = {
288 	{ .compatible = "st,stm32-vrefbuf", },
289 	{},
290 };
291 MODULE_DEVICE_TABLE(of, stm32_vrefbuf_of_match);
292 
293 static struct platform_driver stm32_vrefbuf_driver = {
294 	.probe = stm32_vrefbuf_probe,
295 	.remove = stm32_vrefbuf_remove,
296 	.driver = {
297 		.name  = "stm32-vrefbuf",
298 		.of_match_table = of_match_ptr(stm32_vrefbuf_of_match),
299 		.pm = &stm32_vrefbuf_pm_ops,
300 	},
301 };
302 module_platform_driver(stm32_vrefbuf_driver);
303 
304 MODULE_LICENSE("GPL v2");
305 MODULE_AUTHOR("Fabrice Gasnier <fabrice.gasnier@st.com>");
306 MODULE_DESCRIPTION("STMicroelectronics STM32 VREFBUF driver");
307 MODULE_ALIAS("platform:stm32-vrefbuf");
308