tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
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
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
28struct stm32_vrefbuf {
29 void __iomem *base;
30 struct clk *clk;
31};
32
33static const unsigned int stm32_vrefbuf_voltages[] = {
34 /* Matches resp. VRS = 000b, 001b, 010b, 011b */
35 2500000, 2048000, 1800000, 1500000,
36};
37
38static int stm32_vrefbuf_enable(struct regulator_dev *rdev)
39{
40 struct stm32_vrefbuf *priv = rdev_get_drvdata(rdev);
41 u32 val = readl_relaxed(priv->base + STM32_VREFBUF_CSR);
42 int ret;
43
44 val = (val & ~STM32_HIZ) | STM32_ENVR;
45 writel_relaxed(val, priv->base + STM32_VREFBUF_CSR);
46
47 /*
48 * Vrefbuf startup time depends on external capacitor: wait here for
49 * VRR to be set. That means output has reached expected value.
50 * ~650us sleep should be enough for caps up to 1.5uF. Use 10ms as
51 * arbitrary timeout.
52 */
53 ret = readl_poll_timeout(priv->base + STM32_VREFBUF_CSR, val,
54 val & STM32_VRR, 650, 10000);
55 if (ret) {
56 dev_err(&rdev->dev, "stm32 vrefbuf timed out!\n");
57 val = readl_relaxed(priv->base + STM32_VREFBUF_CSR);
58 val = (val & ~STM32_ENVR) | STM32_HIZ;
59 writel_relaxed(val, priv->base + STM32_VREFBUF_CSR);
60 }
61
62 return ret;
63}
64
65static int stm32_vrefbuf_disable(struct regulator_dev *rdev)
66{
67 struct stm32_vrefbuf *priv = rdev_get_drvdata(rdev);
68 u32 val = readl_relaxed(priv->base + STM32_VREFBUF_CSR);
69
70 val = (val & ~STM32_ENVR) | STM32_HIZ;
71 writel_relaxed(val, priv->base + STM32_VREFBUF_CSR);
72
73 return 0;
74}
75
76static int stm32_vrefbuf_is_enabled(struct regulator_dev *rdev)
77{
78 struct stm32_vrefbuf *priv = rdev_get_drvdata(rdev);
79
80 return readl_relaxed(priv->base + STM32_VREFBUF_CSR) & STM32_ENVR;
81}
82
83static int stm32_vrefbuf_set_voltage_sel(struct regulator_dev *rdev,
84 unsigned sel)
85{
86 struct stm32_vrefbuf *priv = rdev_get_drvdata(rdev);
87 u32 val = readl_relaxed(priv->base + STM32_VREFBUF_CSR);
88
89 val = (val & ~STM32_VRS) | FIELD_PREP(STM32_VRS, sel);
90 writel_relaxed(val, priv->base + STM32_VREFBUF_CSR);
91
92 return 0;
93}
94
95static int stm32_vrefbuf_get_voltage_sel(struct regulator_dev *rdev)
96{
97 struct stm32_vrefbuf *priv = rdev_get_drvdata(rdev);
98 u32 val = readl_relaxed(priv->base + STM32_VREFBUF_CSR);
99
100 return FIELD_GET(STM32_VRS, val);
101}
102
103static const struct regulator_ops stm32_vrefbuf_volt_ops = {
104 .enable = stm32_vrefbuf_enable,
105 .disable = stm32_vrefbuf_disable,
106 .is_enabled = stm32_vrefbuf_is_enabled,
107 .get_voltage_sel = stm32_vrefbuf_get_voltage_sel,
108 .set_voltage_sel = stm32_vrefbuf_set_voltage_sel,
109 .list_voltage = regulator_list_voltage_table,
110};
111
112static const struct regulator_desc stm32_vrefbuf_regu = {
113 .name = "vref",
114 .supply_name = "vdda",
115 .volt_table = stm32_vrefbuf_voltages,
116 .n_voltages = ARRAY_SIZE(stm32_vrefbuf_voltages),
117 .ops = &stm32_vrefbuf_volt_ops,
118 .type = REGULATOR_VOLTAGE,
119 .owner = THIS_MODULE,
120};
121
122static int stm32_vrefbuf_probe(struct platform_device *pdev)
123{
124 struct resource *res;
125 struct stm32_vrefbuf *priv;
126 struct regulator_config config = { };
127 struct regulator_dev *rdev;
128 int ret;
129
130 priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
131 if (!priv)
132 return -ENOMEM;
133
134 res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
135 priv->base = devm_ioremap_resource(&pdev->dev, res);
136 if (IS_ERR(priv->base))
137 return PTR_ERR(priv->base);
138
139 priv->clk = devm_clk_get(&pdev->dev, NULL);
140 if (IS_ERR(priv->clk))
141 return PTR_ERR(priv->clk);
142
143 ret = clk_prepare_enable(priv->clk);
144 if (ret) {
145 dev_err(&pdev->dev, "clk prepare failed with error %d\n", ret);
146 return ret;
147 }
148
149 config.dev = &pdev->dev;
150 config.driver_data = priv;
151 config.of_node = pdev->dev.of_node;
152 config.init_data = of_get_regulator_init_data(&pdev->dev,
153 pdev->dev.of_node,
154 &stm32_vrefbuf_regu);
155
156 rdev = regulator_register(&stm32_vrefbuf_regu, &config);
157 if (IS_ERR(rdev)) {
158 ret = PTR_ERR(rdev);
159 dev_err(&pdev->dev, "register failed with error %d\n", ret);
160 goto err_clk_dis;
161 }
162 platform_set_drvdata(pdev, rdev);
163
164 return 0;
165
166err_clk_dis:
167 clk_disable_unprepare(priv->clk);
168
169 return ret;
170}
171
172static int stm32_vrefbuf_remove(struct platform_device *pdev)
173{
174 struct regulator_dev *rdev = platform_get_drvdata(pdev);
175 struct stm32_vrefbuf *priv = rdev_get_drvdata(rdev);
176
177 regulator_unregister(rdev);
178 clk_disable_unprepare(priv->clk);
179
180 return 0;
181};
182
183static const struct of_device_id stm32_vrefbuf_of_match[] = {
184 { .compatible = "st,stm32-vrefbuf", },
185 {},
186};
187MODULE_DEVICE_TABLE(of, stm32_vrefbuf_of_match);
188
189static struct platform_driver stm32_vrefbuf_driver = {
190 .probe = stm32_vrefbuf_probe,
191 .remove = stm32_vrefbuf_remove,
192 .driver = {
193 .name = "stm32-vrefbuf",
194 .of_match_table = of_match_ptr(stm32_vrefbuf_of_match),
195 },
196};
197module_platform_driver(stm32_vrefbuf_driver);
198
199MODULE_LICENSE("GPL v2");
200MODULE_AUTHOR("Fabrice Gasnier <fabrice.gasnier@st.com>");
201MODULE_DESCRIPTION("STMicroelectronics STM32 VREFBUF driver");
202MODULE_ALIAS("platform:stm32-vrefbuf");