1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3  * Mellanox register access driver
4  *
5  * Copyright (C) 2018 Mellanox Technologies
6  * Copyright (C) 2018 Vadim Pasternak <vadimp@mellanox.com>
7  */
8 
9 #include <linux/bitops.h>
10 #include <linux/device.h>
11 #include <linux/hwmon.h>
12 #include <linux/hwmon-sysfs.h>
13 #include <linux/module.h>
14 #include <linux/of_device.h>
15 #include <linux/platform_data/mlxreg.h>
16 #include <linux/platform_device.h>
17 #include <linux/regmap.h>
18 
19 /* Attribute parameters. */
20 #define MLXREG_IO_ATT_SIZE	10
21 #define MLXREG_IO_ATT_NUM	96
22 
23 /**
24  * struct mlxreg_io_priv_data - driver's private data:
25  *
26  * @pdev: platform device;
27  * @pdata: platform data;
28  * @hwmon: hwmon device;
29  * @mlxreg_io_attr: sysfs attributes array;
30  * @mlxreg_io_dev_attr: sysfs sensor device attribute array;
31  * @group: sysfs attribute group;
32  * @groups: list of sysfs attribute group for hwmon registration;
33  * @regsize: size of a register value;
34  * @io_lock: user access locking;
35  */
36 struct mlxreg_io_priv_data {
37 	struct platform_device *pdev;
38 	struct mlxreg_core_platform_data *pdata;
39 	struct device *hwmon;
40 	struct attribute *mlxreg_io_attr[MLXREG_IO_ATT_NUM + 1];
41 	struct sensor_device_attribute mlxreg_io_dev_attr[MLXREG_IO_ATT_NUM];
42 	struct attribute_group group;
43 	const struct attribute_group *groups[2];
44 	int regsize;
45 	struct mutex io_lock; /* Protects user access. */
46 };
47 
48 static int
49 mlxreg_io_get_reg(void *regmap, struct mlxreg_core_data *data, u32 in_val,
50 		  bool rw_flag, int regsize, u32 *regval)
51 {
52 	int i, val, ret;
53 
54 	ret = regmap_read(regmap, data->reg, regval);
55 	if (ret)
56 		goto access_error;
57 
58 	/*
59 	 * There are four kinds of attributes: single bit, full register's
60 	 * bits, bit sequence, bits in few registers For the first kind field
61 	 * mask indicates which bits are not related and field bit is set zero.
62 	 * For the second kind field mask is set to zero and field bit is set
63 	 * with all bits one. No special handling for such kind of attributes -
64 	 * pass value as is. For the third kind, the field mask indicates which
65 	 * bits are related and the field bit is set to the first bit number
66 	 * (from 1 to 32) is the bit sequence. For the fourth kind - the number
67 	 * of registers which should be read for getting an attribute are
68 	 * specified through 'data->regnum' field.
69 	 */
70 	if (!data->bit) {
71 		/* Single bit. */
72 		if (rw_flag) {
73 			/* For show: expose effective bit value as 0 or 1. */
74 			*regval = !!(*regval & ~data->mask);
75 		} else {
76 			/* For store: set effective bit value. */
77 			*regval &= data->mask;
78 			if (in_val)
79 				*regval |= ~data->mask;
80 		}
81 	} else if (data->mask) {
82 		/* Bit sequence. */
83 		if (rw_flag) {
84 			/* For show: mask and shift right. */
85 			*regval = ror32(*regval & data->mask, (data->bit - 1));
86 		} else {
87 			/* For store: shift to the position and mask. */
88 			in_val = rol32(in_val, data->bit - 1) & data->mask;
89 			/* Clear relevant bits and set them to new value. */
90 			*regval = (*regval & ~data->mask) | in_val;
91 		}
92 	} else {
93 		/*
94 		 * Some attributes could occupied few registers in case regmap
95 		 * bit size is 8 or 16. Compose such attributes from 'regnum'
96 		 * registers. Such attributes contain read-only data.
97 		 */
98 		for (i = 1; i < data->regnum; i++) {
99 			ret = regmap_read(regmap, data->reg + i, &val);
100 			if (ret)
101 				goto access_error;
102 
103 			*regval |= rol32(val, regsize * i * 8);
104 		}
105 	}
106 
107 access_error:
108 	return ret;
109 }
110 
111 static ssize_t
112 mlxreg_io_attr_show(struct device *dev, struct device_attribute *attr,
113 		    char *buf)
114 {
115 	struct mlxreg_io_priv_data *priv = dev_get_drvdata(dev);
116 	int index = to_sensor_dev_attr(attr)->index;
117 	struct mlxreg_core_data *data = priv->pdata->data + index;
118 	u32 regval = 0;
119 	int ret;
120 
121 	mutex_lock(&priv->io_lock);
122 
123 	ret = mlxreg_io_get_reg(priv->pdata->regmap, data, 0, true,
124 				priv->regsize, &regval);
125 	if (ret)
126 		goto access_error;
127 
128 	mutex_unlock(&priv->io_lock);
129 
130 	return sprintf(buf, "%u\n", regval);
131 
132 access_error:
133 	mutex_unlock(&priv->io_lock);
134 	return ret;
135 }
136 
137 static ssize_t
138 mlxreg_io_attr_store(struct device *dev, struct device_attribute *attr,
139 		     const char *buf, size_t len)
140 {
141 	struct mlxreg_io_priv_data *priv = dev_get_drvdata(dev);
142 	int index = to_sensor_dev_attr(attr)->index;
143 	struct mlxreg_core_data *data = priv->pdata->data + index;
144 	u32 input_val, regval;
145 	int ret;
146 
147 	if (len > MLXREG_IO_ATT_SIZE)
148 		return -EINVAL;
149 
150 	/* Convert buffer to input value. */
151 	ret = kstrtou32(buf, 0, &input_val);
152 	if (ret)
153 		return ret;
154 
155 	mutex_lock(&priv->io_lock);
156 
157 	ret = mlxreg_io_get_reg(priv->pdata->regmap, data, input_val, false,
158 				priv->regsize, &regval);
159 	if (ret)
160 		goto access_error;
161 
162 	ret = regmap_write(priv->pdata->regmap, data->reg, regval);
163 	if (ret)
164 		goto access_error;
165 
166 	mutex_unlock(&priv->io_lock);
167 
168 	return len;
169 
170 access_error:
171 	mutex_unlock(&priv->io_lock);
172 	dev_err(&priv->pdev->dev, "Bus access error\n");
173 	return ret;
174 }
175 
176 static struct device_attribute mlxreg_io_devattr_rw = {
177 	.show	= mlxreg_io_attr_show,
178 	.store	= mlxreg_io_attr_store,
179 };
180 
181 static int mlxreg_io_attr_init(struct mlxreg_io_priv_data *priv)
182 {
183 	int i;
184 
185 	priv->group.attrs = devm_kcalloc(&priv->pdev->dev,
186 					 priv->pdata->counter,
187 					 sizeof(struct attribute *),
188 					 GFP_KERNEL);
189 	if (!priv->group.attrs)
190 		return -ENOMEM;
191 
192 	for (i = 0; i < priv->pdata->counter; i++) {
193 		priv->mlxreg_io_attr[i] =
194 				&priv->mlxreg_io_dev_attr[i].dev_attr.attr;
195 		memcpy(&priv->mlxreg_io_dev_attr[i].dev_attr,
196 		       &mlxreg_io_devattr_rw, sizeof(struct device_attribute));
197 
198 		/* Set attribute name as a label. */
199 		priv->mlxreg_io_attr[i]->name =
200 				devm_kasprintf(&priv->pdev->dev, GFP_KERNEL,
201 					       priv->pdata->data[i].label);
202 
203 		if (!priv->mlxreg_io_attr[i]->name) {
204 			dev_err(&priv->pdev->dev, "Memory allocation failed for sysfs attribute %d.\n",
205 				i + 1);
206 			return -ENOMEM;
207 		}
208 
209 		priv->mlxreg_io_dev_attr[i].dev_attr.attr.mode =
210 						priv->pdata->data[i].mode;
211 		priv->mlxreg_io_dev_attr[i].dev_attr.attr.name =
212 					priv->mlxreg_io_attr[i]->name;
213 		priv->mlxreg_io_dev_attr[i].index = i;
214 		sysfs_attr_init(&priv->mlxreg_io_dev_attr[i].dev_attr.attr);
215 	}
216 
217 	priv->group.attrs = priv->mlxreg_io_attr;
218 	priv->groups[0] = &priv->group;
219 	priv->groups[1] = NULL;
220 
221 	return 0;
222 }
223 
224 static int mlxreg_io_probe(struct platform_device *pdev)
225 {
226 	struct mlxreg_io_priv_data *priv;
227 	int err;
228 
229 	priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
230 	if (!priv)
231 		return -ENOMEM;
232 
233 	priv->pdata = dev_get_platdata(&pdev->dev);
234 	if (!priv->pdata) {
235 		dev_err(&pdev->dev, "Failed to get platform data.\n");
236 		return -EINVAL;
237 	}
238 
239 	priv->pdev = pdev;
240 	priv->regsize = regmap_get_val_bytes(priv->pdata->regmap);
241 	if (priv->regsize < 0)
242 		return priv->regsize;
243 
244 	err = mlxreg_io_attr_init(priv);
245 	if (err) {
246 		dev_err(&priv->pdev->dev, "Failed to allocate attributes: %d\n",
247 			err);
248 		return err;
249 	}
250 
251 	priv->hwmon = devm_hwmon_device_register_with_groups(&pdev->dev,
252 							     "mlxreg_io",
253 							      priv,
254 							      priv->groups);
255 	if (IS_ERR(priv->hwmon)) {
256 		dev_err(&pdev->dev, "Failed to register hwmon device %ld\n",
257 			PTR_ERR(priv->hwmon));
258 		return PTR_ERR(priv->hwmon);
259 	}
260 
261 	mutex_init(&priv->io_lock);
262 	dev_set_drvdata(&pdev->dev, priv);
263 
264 	return 0;
265 }
266 
267 static int mlxreg_io_remove(struct platform_device *pdev)
268 {
269 	struct mlxreg_io_priv_data *priv = dev_get_drvdata(&pdev->dev);
270 
271 	mutex_destroy(&priv->io_lock);
272 
273 	return 0;
274 }
275 
276 static struct platform_driver mlxreg_io_driver = {
277 	.driver = {
278 	    .name = "mlxreg-io",
279 	},
280 	.probe = mlxreg_io_probe,
281 	.remove = mlxreg_io_remove,
282 };
283 
284 module_platform_driver(mlxreg_io_driver);
285 
286 MODULE_AUTHOR("Vadim Pasternak <vadimp@mellanox.com>");
287 MODULE_DESCRIPTION("Mellanox regmap I/O access driver");
288 MODULE_LICENSE("GPL");
289 MODULE_ALIAS("platform:mlxreg-io");
290