regulator: Add support for stm32-vrefbuf
[sfrench/cifs-2.6.git] / drivers / regulator / stm32-vrefbuf.c
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
28 struct stm32_vrefbuf {
29         void __iomem *base;
30         struct clk *clk;
31 };
32
33 static const unsigned int stm32_vrefbuf_voltages[] = {
34         /* Matches resp. VRS = 000b, 001b, 010b, 011b */
35         2500000, 2048000, 1800000, 1500000,
36 };
37
38 static 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
65 static 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
76 static 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
83 static 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
95 static 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
103 static 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
112 static 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
122 static 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
166 err_clk_dis:
167         clk_disable_unprepare(priv->clk);
168
169         return ret;
170 }
171
172 static 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
183 static const struct of_device_id stm32_vrefbuf_of_match[] = {
184         { .compatible = "st,stm32-vrefbuf", },
185         {},
186 };
187 MODULE_DEVICE_TABLE(of, stm32_vrefbuf_of_match);
188
189 static 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 };
197 module_platform_driver(stm32_vrefbuf_driver);
198
199 MODULE_LICENSE("GPL v2");
200 MODULE_AUTHOR("Fabrice Gasnier <fabrice.gasnier@st.com>");
201 MODULE_DESCRIPTION("STMicroelectronics STM32 VREFBUF driver");
202 MODULE_ALIAS("platform:stm32-vrefbuf");