1 /*
2 * max1111.c - +2.7V, Low-Power, Multichannel, Serial 8-bit ADCs
3 *
4 * Based on arch/arm/mach-pxa/corgi_ssp.c
5 *
6 * Copyright (C) 2004-2005 Richard Purdie
7 *
8 * Copyright (C) 2008 Marvell International Ltd.
9 * Eric Miao <eric.miao@marvell.com>
10 *
11 * This program is free software; you can redistribute it and/or modify
12 * it under the terms of the GNU General Public License version 2 as
13 * publishhed by the Free Software Foundation.
14 */
15
16 #include <linux/module.h>
17 #include <linux/kernel.h>
18 #include <linux/init.h>
19 #include <linux/err.h>
20 #include <linux/hwmon.h>
21 #include <linux/hwmon-sysfs.h>
22 #include <linux/spi/spi.h>
23 #include <linux/slab.h>
24
25 #define MAX1111_TX_BUF_SIZE 1
26 #define MAX1111_RX_BUF_SIZE 2
27
28 /* MAX1111 Commands */
29 #define MAX1111_CTRL_PD0 (1u << 0)
30 #define MAX1111_CTRL_PD1 (1u << 1)
31 #define MAX1111_CTRL_SGL (1u << 2)
32 #define MAX1111_CTRL_UNI (1u << 3)
33 #define MAX1111_CTRL_SEL_SH (5) /* NOTE: bit 4 is ignored */
34 #define MAX1111_CTRL_STR (1u << 7)
35
36 struct max1111_data {
37 struct spi_device *spi;
38 struct device *hwmon_dev;
39 struct spi_message msg;
40 struct spi_transfer xfer[2];
41 uint8_t *tx_buf;
42 uint8_t *rx_buf;
43 };
44
max1111_read(struct device * dev,int channel)45 static int max1111_read(struct device *dev, int channel)
46 {
47 struct max1111_data *data = dev_get_drvdata(dev);
48 uint8_t v1, v2;
49 int err;
50
51 data->tx_buf[0] = (channel << MAX1111_CTRL_SEL_SH) |
52 MAX1111_CTRL_PD0 | MAX1111_CTRL_PD1 |
53 MAX1111_CTRL_SGL | MAX1111_CTRL_UNI | MAX1111_CTRL_STR;
54
55 err = spi_sync(data->spi, &data->msg);
56 if (err < 0) {
57 dev_err(dev, "spi_sync failed with %d\n", err);
58 return err;
59 }
60
61 v1 = data->rx_buf[0];
62 v2 = data->rx_buf[1];
63
64 if ((v1 & 0xc0) || (v2 & 0x3f))
65 return -EINVAL;
66
67 return (v1 << 2) | (v2 >> 6);
68 }
69
70 #ifdef CONFIG_SHARPSL_PM
71 static struct max1111_data *the_max1111;
72
max1111_read_channel(int channel)73 int max1111_read_channel(int channel)
74 {
75 return max1111_read(&the_max1111->spi->dev, channel);
76 }
77 EXPORT_SYMBOL(max1111_read_channel);
78 #endif
79
80 /*
81 * NOTE: SPI devices do not have a default 'name' attribute, which is
82 * likely to be used by hwmon applications to distinguish between
83 * different devices, explicitly add a name attribute here.
84 */
show_name(struct device * dev,struct device_attribute * attr,char * buf)85 static ssize_t show_name(struct device *dev,
86 struct device_attribute *attr, char *buf)
87 {
88 return sprintf(buf, "max1111\n");
89 }
90
show_adc(struct device * dev,struct device_attribute * attr,char * buf)91 static ssize_t show_adc(struct device *dev,
92 struct device_attribute *attr, char *buf)
93 {
94 int channel = to_sensor_dev_attr(attr)->index;
95 int ret;
96
97 ret = max1111_read(dev, channel);
98 if (ret < 0)
99 return ret;
100
101 return sprintf(buf, "%d\n", ret);
102 }
103
104 #define MAX1111_ADC_ATTR(_id) \
105 SENSOR_DEVICE_ATTR(adc##_id##_in, S_IRUGO, show_adc, NULL, _id)
106
107 static DEVICE_ATTR(name, S_IRUGO, show_name, NULL);
108 static MAX1111_ADC_ATTR(0);
109 static MAX1111_ADC_ATTR(1);
110 static MAX1111_ADC_ATTR(2);
111 static MAX1111_ADC_ATTR(3);
112
113 static struct attribute *max1111_attributes[] = {
114 &dev_attr_name.attr,
115 &sensor_dev_attr_adc0_in.dev_attr.attr,
116 &sensor_dev_attr_adc1_in.dev_attr.attr,
117 &sensor_dev_attr_adc2_in.dev_attr.attr,
118 &sensor_dev_attr_adc3_in.dev_attr.attr,
119 NULL,
120 };
121
122 static const struct attribute_group max1111_attr_group = {
123 .attrs = max1111_attributes,
124 };
125
setup_transfer(struct max1111_data * data)126 static int setup_transfer(struct max1111_data *data)
127 {
128 struct spi_message *m;
129 struct spi_transfer *x;
130
131 data->tx_buf = kmalloc(MAX1111_TX_BUF_SIZE, GFP_KERNEL);
132 if (!data->tx_buf)
133 return -ENOMEM;
134
135 data->rx_buf = kmalloc(MAX1111_RX_BUF_SIZE, GFP_KERNEL);
136 if (!data->rx_buf) {
137 kfree(data->tx_buf);
138 return -ENOMEM;
139 }
140
141 m = &data->msg;
142 x = &data->xfer[0];
143
144 spi_message_init(m);
145
146 x->tx_buf = &data->tx_buf[0];
147 x->len = 1;
148 spi_message_add_tail(x, m);
149
150 x++;
151 x->rx_buf = &data->rx_buf[0];
152 x->len = 2;
153 spi_message_add_tail(x, m);
154
155 return 0;
156 }
157
max1111_probe(struct spi_device * spi)158 static int __devinit max1111_probe(struct spi_device *spi)
159 {
160 struct max1111_data *data;
161 int err;
162
163 spi->bits_per_word = 8;
164 spi->mode = SPI_MODE_0;
165 err = spi_setup(spi);
166 if (err < 0)
167 return err;
168
169 data = kzalloc(sizeof(struct max1111_data), GFP_KERNEL);
170 if (data == NULL) {
171 dev_err(&spi->dev, "failed to allocate memory\n");
172 return -ENOMEM;
173 }
174
175 err = setup_transfer(data);
176 if (err)
177 goto err_free_data;
178
179 data->spi = spi;
180 spi_set_drvdata(spi, data);
181
182 err = sysfs_create_group(&spi->dev.kobj, &max1111_attr_group);
183 if (err) {
184 dev_err(&spi->dev, "failed to create attribute group\n");
185 goto err_free_all;
186 }
187
188 data->hwmon_dev = hwmon_device_register(&spi->dev);
189 if (IS_ERR(data->hwmon_dev)) {
190 dev_err(&spi->dev, "failed to create hwmon device\n");
191 err = PTR_ERR(data->hwmon_dev);
192 goto err_remove;
193 }
194
195 #ifdef CONFIG_SHARPSL_PM
196 the_max1111 = data;
197 #endif
198 return 0;
199
200 err_remove:
201 sysfs_remove_group(&spi->dev.kobj, &max1111_attr_group);
202 err_free_all:
203 kfree(data->rx_buf);
204 kfree(data->tx_buf);
205 err_free_data:
206 kfree(data);
207 return err;
208 }
209
max1111_remove(struct spi_device * spi)210 static int __devexit max1111_remove(struct spi_device *spi)
211 {
212 struct max1111_data *data = spi_get_drvdata(spi);
213
214 hwmon_device_unregister(data->hwmon_dev);
215 sysfs_remove_group(&spi->dev.kobj, &max1111_attr_group);
216 kfree(data->rx_buf);
217 kfree(data->tx_buf);
218 kfree(data);
219 return 0;
220 }
221
222 static struct spi_driver max1111_driver = {
223 .driver = {
224 .name = "max1111",
225 .owner = THIS_MODULE,
226 },
227 .probe = max1111_probe,
228 .remove = __devexit_p(max1111_remove),
229 };
230
max1111_init(void)231 static int __init max1111_init(void)
232 {
233 return spi_register_driver(&max1111_driver);
234 }
235 module_init(max1111_init);
236
max1111_exit(void)237 static void __exit max1111_exit(void)
238 {
239 spi_unregister_driver(&max1111_driver);
240 }
241 module_exit(max1111_exit);
242
243 MODULE_AUTHOR("Eric Miao <eric.miao@marvell.com>");
244 MODULE_DESCRIPTION("MAX1111 ADC Driver");
245 MODULE_LICENSE("GPL");
246 MODULE_ALIAS("spi:max1111");
247