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