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  
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_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  
stm32_vrefbuf_disable(struct regulator_dev * rdev)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  
stm32_vrefbuf_is_enabled(struct regulator_dev * rdev)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  
stm32_vrefbuf_set_voltage_sel(struct regulator_dev * rdev,unsigned sel)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  
stm32_vrefbuf_get_voltage_sel(struct regulator_dev * rdev)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  
stm32_vrefbuf_probe(struct platform_device * pdev)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  
stm32_vrefbuf_remove(struct platform_device * pdev)236  static 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  
stm32_vrefbuf_runtime_suspend(struct device * dev)249  static 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  
stm32_vrefbuf_runtime_resume(struct device * dev)259  static 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  
267  static 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  
275  static const struct of_device_id __maybe_unused stm32_vrefbuf_of_match[] = {
276  	{ .compatible = "st,stm32-vrefbuf", },
277  	{},
278  };
279  MODULE_DEVICE_TABLE(of, stm32_vrefbuf_of_match);
280  
281  static 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  };
291  module_platform_driver(stm32_vrefbuf_driver);
292  
293  MODULE_LICENSE("GPL v2");
294  MODULE_AUTHOR("Fabrice Gasnier <fabrice.gasnier@st.com>");
295  MODULE_DESCRIPTION("STMicroelectronics STM32 VREFBUF driver");
296  MODULE_ALIAS("platform:stm32-vrefbuf");
297