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
 30struct stm32_vrefbuf {
 31	void __iomem *base;
 32	struct clk *clk;
 33	struct device *dev;
 34};
 35
 36static const unsigned int stm32_vrefbuf_voltages[] = {
 37	/* Matches resp. VRS = 000b, 001b, 010b, 011b */
 38	2500000, 2048000, 1800000, 1500000,
 39};
 40
 41static 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
 78static 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
100static 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
119static 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
142static 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
163static 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
172static 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
183static 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
236err_clk_dis:
237	clk_disable_unprepare(priv->clk);
238err_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
246static 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
261static 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
271static 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
279static 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
287static const struct of_device_id __maybe_unused stm32_vrefbuf_of_match[] = {
288	{ .compatible = "st,stm32-vrefbuf", },
289	{},
290};
291MODULE_DEVICE_TABLE(of, stm32_vrefbuf_of_match);
292
293static 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};
302module_platform_driver(stm32_vrefbuf_driver);
303
304MODULE_LICENSE("GPL v2");
305MODULE_AUTHOR("Fabrice Gasnier <fabrice.gasnier@st.com>");
306MODULE_DESCRIPTION("STMicroelectronics STM32 VREFBUF driver");
307MODULE_ALIAS("platform:stm32-vrefbuf");