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[MAX1111_TX_BUF_SIZE]; 42 uint8_t rx_buf[MAX1111_RX_BUF_SIZE]; 43 struct mutex drvdata_lock; 44 /* protect msg, xfer and buffers from multiple access */ 45 }; 46 47 static int max1111_read(struct device *dev, int channel) 48 { 49 struct max1111_data *data = dev_get_drvdata(dev); 50 uint8_t v1, v2; 51 int err; 52 53 /* writing to drvdata struct is not thread safe, wait on mutex */ 54 mutex_lock(&data->drvdata_lock); 55 56 data->tx_buf[0] = (channel << MAX1111_CTRL_SEL_SH) | 57 MAX1111_CTRL_PD0 | MAX1111_CTRL_PD1 | 58 MAX1111_CTRL_SGL | MAX1111_CTRL_UNI | MAX1111_CTRL_STR; 59 60 err = spi_sync(data->spi, &data->msg); 61 if (err < 0) { 62 dev_err(dev, "spi_sync failed with %d\n", err); 63 mutex_unlock(&data->drvdata_lock); 64 return err; 65 } 66 67 v1 = data->rx_buf[0]; 68 v2 = data->rx_buf[1]; 69 70 mutex_unlock(&data->drvdata_lock); 71 72 if ((v1 & 0xc0) || (v2 & 0x3f)) 73 return -EINVAL; 74 75 return (v1 << 2) | (v2 >> 6); 76 } 77 78 #ifdef CONFIG_SHARPSL_PM 79 static struct max1111_data *the_max1111; 80 81 int max1111_read_channel(int channel) 82 { 83 return max1111_read(&the_max1111->spi->dev, channel); 84 } 85 EXPORT_SYMBOL(max1111_read_channel); 86 #endif 87 88 /* 89 * NOTE: SPI devices do not have a default 'name' attribute, which is 90 * likely to be used by hwmon applications to distinguish between 91 * different devices, explicitly add a name attribute here. 92 */ 93 static ssize_t show_name(struct device *dev, 94 struct device_attribute *attr, char *buf) 95 { 96 return sprintf(buf, "max1111\n"); 97 } 98 99 static ssize_t show_adc(struct device *dev, 100 struct device_attribute *attr, char *buf) 101 { 102 int channel = to_sensor_dev_attr(attr)->index; 103 int ret; 104 105 ret = max1111_read(dev, channel); 106 if (ret < 0) 107 return ret; 108 109 /* assume the reference voltage to be 2.048V, with an 8-bit sample, 110 * the LSB weight is 8mV 111 */ 112 return sprintf(buf, "%d\n", ret * 8); 113 } 114 115 #define MAX1111_ADC_ATTR(_id) \ 116 SENSOR_DEVICE_ATTR(in##_id##_input, S_IRUGO, show_adc, NULL, _id) 117 118 static DEVICE_ATTR(name, S_IRUGO, show_name, NULL); 119 static MAX1111_ADC_ATTR(0); 120 static MAX1111_ADC_ATTR(1); 121 static MAX1111_ADC_ATTR(2); 122 static MAX1111_ADC_ATTR(3); 123 124 static struct attribute *max1111_attributes[] = { 125 &dev_attr_name.attr, 126 &sensor_dev_attr_in0_input.dev_attr.attr, 127 &sensor_dev_attr_in1_input.dev_attr.attr, 128 &sensor_dev_attr_in2_input.dev_attr.attr, 129 &sensor_dev_attr_in3_input.dev_attr.attr, 130 NULL, 131 }; 132 133 static const struct attribute_group max1111_attr_group = { 134 .attrs = max1111_attributes, 135 }; 136 137 static int __devinit setup_transfer(struct max1111_data *data) 138 { 139 struct spi_message *m; 140 struct spi_transfer *x; 141 142 m = &data->msg; 143 x = &data->xfer[0]; 144 145 spi_message_init(m); 146 147 x->tx_buf = &data->tx_buf[0]; 148 x->len = MAX1111_TX_BUF_SIZE; 149 spi_message_add_tail(x, m); 150 151 x++; 152 x->rx_buf = &data->rx_buf[0]; 153 x->len = MAX1111_RX_BUF_SIZE; 154 spi_message_add_tail(x, m); 155 156 return 0; 157 } 158 159 static int __devinit max1111_probe(struct spi_device *spi) 160 { 161 struct max1111_data *data; 162 int err; 163 164 spi->bits_per_word = 8; 165 spi->mode = SPI_MODE_0; 166 err = spi_setup(spi); 167 if (err < 0) 168 return err; 169 170 data = kzalloc(sizeof(struct max1111_data), GFP_KERNEL); 171 if (data == NULL) { 172 dev_err(&spi->dev, "failed to allocate memory\n"); 173 return -ENOMEM; 174 } 175 176 err = setup_transfer(data); 177 if (err) 178 goto err_free_data; 179 180 mutex_init(&data->drvdata_lock); 181 182 data->spi = spi; 183 spi_set_drvdata(spi, data); 184 185 err = sysfs_create_group(&spi->dev.kobj, &max1111_attr_group); 186 if (err) { 187 dev_err(&spi->dev, "failed to create attribute group\n"); 188 goto err_free_data; 189 } 190 191 data->hwmon_dev = hwmon_device_register(&spi->dev); 192 if (IS_ERR(data->hwmon_dev)) { 193 dev_err(&spi->dev, "failed to create hwmon device\n"); 194 err = PTR_ERR(data->hwmon_dev); 195 goto err_remove; 196 } 197 198 #ifdef CONFIG_SHARPSL_PM 199 the_max1111 = data; 200 #endif 201 return 0; 202 203 err_remove: 204 sysfs_remove_group(&spi->dev.kobj, &max1111_attr_group); 205 err_free_data: 206 kfree(data); 207 return err; 208 } 209 210 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 mutex_destroy(&data->drvdata_lock); 217 kfree(data); 218 return 0; 219 } 220 221 static struct spi_driver max1111_driver = { 222 .driver = { 223 .name = "max1111", 224 .owner = THIS_MODULE, 225 }, 226 .probe = max1111_probe, 227 .remove = __devexit_p(max1111_remove), 228 }; 229 230 static int __init max1111_init(void) 231 { 232 return spi_register_driver(&max1111_driver); 233 } 234 module_init(max1111_init); 235 236 static void __exit max1111_exit(void) 237 { 238 spi_unregister_driver(&max1111_driver); 239 } 240 module_exit(max1111_exit); 241 242 MODULE_AUTHOR("Eric Miao <eric.miao@marvell.com>"); 243 MODULE_DESCRIPTION("MAX1111 ADC Driver"); 244 MODULE_LICENSE("GPL"); 245 MODULE_ALIAS("spi:max1111"); 246