1/*
2 * Copyright (C) STMicroelectronics 2017
3 *
4 * Author: Fabrice Gasnier <fabrice.gasnier@st.com>
5 *
6 * License terms: GNU General Public License (GPL), version 2
7 */
8
9#include <linux/bitfield.h>
10#include <linux/clk.h>
11#include <linux/io.h>
12#include <linux/iopoll.h>
13#include <linux/module.h>
14#include <linux/of_device.h>
15#include <linux/platform_device.h>
16#include <linux/regulator/driver.h>
17#include <linux/regulator/of_regulator.h>
18#include <linux/pm_runtime.h>
19
20/* STM32 VREFBUF registers */
21#define STM32_VREFBUF_CSR 0x00
22
23/* STM32 VREFBUF CSR bitfields */
24#define STM32_VRS GENMASK(6, 4)
25#define STM32_VRR BIT(3)
26#define STM32_HIZ BIT(1)
27#define STM32_ENVR BIT(0)
28
29#define STM32_VREFBUF_AUTO_SUSPEND_DELAY_MS 10
30
31struct stm32_vrefbuf {
32 void __iomem *base;
33 struct clk *clk;
34 struct device *dev;
35};
36
37static const unsigned int stm32_vrefbuf_voltages[] = {
38 /* Matches resp. VRS = 000b, 001b, 010b, 011b */
39 2500000, 2048000, 1800000, 1500000,
40};
41
42static int stm32_vrefbuf_enable(struct regulator_dev *rdev)
43{
44 struct stm32_vrefbuf *priv = rdev_get_drvdata(rdev);
45 u32 val;
46 int ret;
47
48 ret = pm_runtime_get_sync(priv->dev);
49 if (ret < 0) {
50 pm_runtime_put_noidle(priv->dev);
51 return ret;
52 }
53
54 val = readl_relaxed(priv->base + STM32_VREFBUF_CSR);
55 val = (val & ~STM32_HIZ) | STM32_ENVR;
56 writel_relaxed(val, priv->base + STM32_VREFBUF_CSR);
57
58 /*
59 * Vrefbuf startup time depends on external capacitor: wait here for
60 * VRR to be set. That means output has reached expected value.
61 * ~650us sleep should be enough for caps up to 1.5uF. Use 10ms as
62 * arbitrary timeout.
63 */
64 ret = readl_poll_timeout(priv->base + STM32_VREFBUF_CSR, val,
65 val & STM32_VRR, 650, 10000);
66 if (ret) {
67 dev_err(&rdev->dev, "stm32 vrefbuf timed out!\n");
68 val = readl_relaxed(priv->base + STM32_VREFBUF_CSR);
69 val = (val & ~STM32_ENVR) | STM32_HIZ;
70 writel_relaxed(val, priv->base + STM32_VREFBUF_CSR);
71 }
72
73 pm_runtime_mark_last_busy(priv->dev);
74 pm_runtime_put_autosuspend(priv->dev);
75
76 return ret;
77}
78
79static int stm32_vrefbuf_disable(struct regulator_dev *rdev)
80{
81 struct stm32_vrefbuf *priv = rdev_get_drvdata(rdev);
82 u32 val;
83 int ret;
84
85 ret = pm_runtime_get_sync(priv->dev);
86 if (ret < 0) {
87 pm_runtime_put_noidle(priv->dev);
88 return ret;
89 }
90
91 val = readl_relaxed(priv->base + STM32_VREFBUF_CSR);
92 val = (val & ~STM32_ENVR) | STM32_HIZ;
93 writel_relaxed(val, priv->base + STM32_VREFBUF_CSR);
94
95 pm_runtime_mark_last_busy(priv->dev);
96 pm_runtime_put_autosuspend(priv->dev);
97
98 return 0;
99}
100
101static int stm32_vrefbuf_is_enabled(struct regulator_dev *rdev)
102{
103 struct stm32_vrefbuf *priv = rdev_get_drvdata(rdev);
104 int ret;
105
106 ret = pm_runtime_get_sync(priv->dev);
107 if (ret < 0) {
108 pm_runtime_put_noidle(priv->dev);
109 return ret;
110 }
111
112 ret = readl_relaxed(priv->base + STM32_VREFBUF_CSR) & STM32_ENVR;
113
114 pm_runtime_mark_last_busy(priv->dev);
115 pm_runtime_put_autosuspend(priv->dev);
116
117 return ret;
118}
119
120static int stm32_vrefbuf_set_voltage_sel(struct regulator_dev *rdev,
121 unsigned sel)
122{
123 struct stm32_vrefbuf *priv = rdev_get_drvdata(rdev);
124 u32 val;
125 int ret;
126
127 ret = pm_runtime_get_sync(priv->dev);
128 if (ret < 0) {
129 pm_runtime_put_noidle(priv->dev);
130 return ret;
131 }
132
133 val = readl_relaxed(priv->base + STM32_VREFBUF_CSR);
134 val = (val & ~STM32_VRS) | FIELD_PREP(STM32_VRS, sel);
135 writel_relaxed(val, priv->base + STM32_VREFBUF_CSR);
136
137 pm_runtime_mark_last_busy(priv->dev);
138 pm_runtime_put_autosuspend(priv->dev);
139
140 return 0;
141}
142
143static int stm32_vrefbuf_get_voltage_sel(struct regulator_dev *rdev)
144{
145 struct stm32_vrefbuf *priv = rdev_get_drvdata(rdev);
146 u32 val;
147 int ret;
148
149 ret = pm_runtime_get_sync(priv->dev);
150 if (ret < 0) {
151 pm_runtime_put_noidle(priv->dev);
152 return ret;
153 }
154
155 val = readl_relaxed(priv->base + STM32_VREFBUF_CSR);
156 ret = FIELD_GET(STM32_VRS, val);
157
158 pm_runtime_mark_last_busy(priv->dev);
159 pm_runtime_put_autosuspend(priv->dev);
160
161 return ret;
162}
163
164static const struct regulator_ops stm32_vrefbuf_volt_ops = {
165 .enable = stm32_vrefbuf_enable,
166 .disable = stm32_vrefbuf_disable,
167 .is_enabled = stm32_vrefbuf_is_enabled,
168 .get_voltage_sel = stm32_vrefbuf_get_voltage_sel,
169 .set_voltage_sel = stm32_vrefbuf_set_voltage_sel,
170 .list_voltage = regulator_list_voltage_table,
171};
172
173static const struct regulator_desc stm32_vrefbuf_regu = {
174 .name = "vref",
175 .supply_name = "vdda",
176 .volt_table = stm32_vrefbuf_voltages,
177 .n_voltages = ARRAY_SIZE(stm32_vrefbuf_voltages),
178 .ops = &stm32_vrefbuf_volt_ops,
179 .type = REGULATOR_VOLTAGE,
180 .owner = THIS_MODULE,
181};
182
183static int stm32_vrefbuf_probe(struct platform_device *pdev)
184{
185 struct resource *res;
186 struct stm32_vrefbuf *priv;
187 struct regulator_config config = { };
188 struct regulator_dev *rdev;
189 int ret;
190
191 priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
192 if (!priv)
193 return -ENOMEM;
194 priv->dev = &pdev->dev;
195
196 res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
197 priv->base = devm_ioremap_resource(&pdev->dev, res);
198 if (IS_ERR(priv->base))
199 return PTR_ERR(priv->base);
200
201 priv->clk = devm_clk_get(&pdev->dev, NULL);
202 if (IS_ERR(priv->clk))
203 return PTR_ERR(priv->clk);
204
205 pm_runtime_get_noresume(&pdev->dev);
206 pm_runtime_set_active(&pdev->dev);
207 pm_runtime_set_autosuspend_delay(&pdev->dev,
208 STM32_VREFBUF_AUTO_SUSPEND_DELAY_MS);
209 pm_runtime_use_autosuspend(&pdev->dev);
210 pm_runtime_enable(&pdev->dev);
211
212 ret = clk_prepare_enable(priv->clk);
213 if (ret) {
214 dev_err(&pdev->dev, "clk prepare failed with error %d\n", ret);
215 goto err_pm_stop;
216 }
217
218 config.dev = &pdev->dev;
219 config.driver_data = priv;
220 config.of_node = pdev->dev.of_node;
221 config.init_data = of_get_regulator_init_data(&pdev->dev,
222 pdev->dev.of_node,
223 &stm32_vrefbuf_regu);
224
225 rdev = regulator_register(&stm32_vrefbuf_regu, &config);
226 if (IS_ERR(rdev)) {
227 ret = PTR_ERR(rdev);
228 dev_err(&pdev->dev, "register failed with error %d\n", ret);
229 goto err_clk_dis;
230 }
231 platform_set_drvdata(pdev, rdev);
232
233 pm_runtime_mark_last_busy(&pdev->dev);
234 pm_runtime_put_autosuspend(&pdev->dev);
235
236 return 0;
237
238err_clk_dis:
239 clk_disable_unprepare(priv->clk);
240err_pm_stop:
241 pm_runtime_disable(&pdev->dev);
242 pm_runtime_set_suspended(&pdev->dev);
243 pm_runtime_put_noidle(&pdev->dev);
244
245 return ret;
246}
247
248static int stm32_vrefbuf_remove(struct platform_device *pdev)
249{
250 struct regulator_dev *rdev = platform_get_drvdata(pdev);
251 struct stm32_vrefbuf *priv = rdev_get_drvdata(rdev);
252
253 pm_runtime_get_sync(&pdev->dev);
254 regulator_unregister(rdev);
255 clk_disable_unprepare(priv->clk);
256 pm_runtime_disable(&pdev->dev);
257 pm_runtime_set_suspended(&pdev->dev);
258 pm_runtime_put_noidle(&pdev->dev);
259
260 return 0;
261};
262
263static int __maybe_unused stm32_vrefbuf_runtime_suspend(struct device *dev)
264{
265 struct regulator_dev *rdev = dev_get_drvdata(dev);
266 struct stm32_vrefbuf *priv = rdev_get_drvdata(rdev);
267
268 clk_disable_unprepare(priv->clk);
269
270 return 0;
271}
272
273static int __maybe_unused stm32_vrefbuf_runtime_resume(struct device *dev)
274{
275 struct regulator_dev *rdev = dev_get_drvdata(dev);
276 struct stm32_vrefbuf *priv = rdev_get_drvdata(rdev);
277
278 return clk_prepare_enable(priv->clk);
279}
280
281static const struct dev_pm_ops stm32_vrefbuf_pm_ops = {
282 SET_SYSTEM_SLEEP_PM_OPS(pm_runtime_force_suspend,
283 pm_runtime_force_resume)
284 SET_RUNTIME_PM_OPS(stm32_vrefbuf_runtime_suspend,
285 stm32_vrefbuf_runtime_resume,
286 NULL)
287};
288
289static const struct of_device_id stm32_vrefbuf_of_match[] = {
290 { .compatible = "st,stm32-vrefbuf", },
291 {},
292};
293MODULE_DEVICE_TABLE(of, stm32_vrefbuf_of_match);
294
295static struct platform_driver stm32_vrefbuf_driver = {
296 .probe = stm32_vrefbuf_probe,
297 .remove = stm32_vrefbuf_remove,
298 .driver = {
299 .name = "stm32-vrefbuf",
300 .of_match_table = of_match_ptr(stm32_vrefbuf_of_match),
301 .pm = &stm32_vrefbuf_pm_ops,
302 },
303};
304module_platform_driver(stm32_vrefbuf_driver);
305
306MODULE_LICENSE("GPL v2");
307MODULE_AUTHOR("Fabrice Gasnier <fabrice.gasnier@st.com>");
308MODULE_DESCRIPTION("STMicroelectronics STM32 VREFBUF driver");
309MODULE_ALIAS("platform:stm32-vrefbuf");
310