stm32-vrefbuf.c

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