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 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 return sprintf(buf, "%d\n", ret); 110 } 111 112 #define MAX1111_ADC_ATTR(_id) \ 113 SENSOR_DEVICE_ATTR(adc##_id##_in, S_IRUGO, show_adc, NULL, _id) 114 115 static DEVICE_ATTR(name, S_IRUGO, show_name, NULL); 116 static MAX1111_ADC_ATTR(0); 117 static MAX1111_ADC_ATTR(1); 118 static MAX1111_ADC_ATTR(2); 119 static MAX1111_ADC_ATTR(3); 120 121 static struct attribute *max1111_attributes[] = { 122 &dev_attr_name.attr, 123 &sensor_dev_attr_adc0_in.dev_attr.attr, 124 &sensor_dev_attr_adc1_in.dev_attr.attr, 125 &sensor_dev_attr_adc2_in.dev_attr.attr, 126 &sensor_dev_attr_adc3_in.dev_attr.attr, 127 NULL, 128 }; 129 130 static const struct attribute_group max1111_attr_group = { 131 .attrs = max1111_attributes, 132 }; 133 134 static int setup_transfer(struct max1111_data *data) 135 { 136 struct spi_message *m; 137 struct spi_transfer *x; 138 139 data->tx_buf = kmalloc(MAX1111_TX_BUF_SIZE, GFP_KERNEL); 140 if (!data->tx_buf) 141 return -ENOMEM; 142 143 data->rx_buf = kmalloc(MAX1111_RX_BUF_SIZE, GFP_KERNEL); 144 if (!data->rx_buf) { 145 kfree(data->tx_buf); 146 return -ENOMEM; 147 } 148 149 m = &data->msg; 150 x = &data->xfer[0]; 151 152 spi_message_init(m); 153 154 x->tx_buf = &data->tx_buf[0]; 155 x->len = 1; 156 spi_message_add_tail(x, m); 157 158 x++; 159 x->rx_buf = &data->rx_buf[0]; 160 x->len = 2; 161 spi_message_add_tail(x, m); 162 163 return 0; 164 } 165 166 static int __devinit max1111_probe(struct spi_device *spi) 167 { 168 struct max1111_data *data; 169 int err; 170 171 spi->bits_per_word = 8; 172 spi->mode = SPI_MODE_0; 173 err = spi_setup(spi); 174 if (err < 0) 175 return err; 176 177 data = kzalloc(sizeof(struct max1111_data), GFP_KERNEL); 178 if (data == NULL) { 179 dev_err(&spi->dev, "failed to allocate memory\n"); 180 return -ENOMEM; 181 } 182 183 err = setup_transfer(data); 184 if (err) 185 goto err_free_data; 186 187 mutex_init(&data->drvdata_lock); 188 189 data->spi = spi; 190 spi_set_drvdata(spi, data); 191 192 err = sysfs_create_group(&spi->dev.kobj, &max1111_attr_group); 193 if (err) { 194 dev_err(&spi->dev, "failed to create attribute group\n"); 195 goto err_free_all; 196 } 197 198 data->hwmon_dev = hwmon_device_register(&spi->dev); 199 if (IS_ERR(data->hwmon_dev)) { 200 dev_err(&spi->dev, "failed to create hwmon device\n"); 201 err = PTR_ERR(data->hwmon_dev); 202 goto err_remove; 203 } 204 205 #ifdef CONFIG_SHARPSL_PM 206 the_max1111 = data; 207 #endif 208 return 0; 209 210 err_remove: 211 sysfs_remove_group(&spi->dev.kobj, &max1111_attr_group); 212 err_free_all: 213 kfree(data->rx_buf); 214 kfree(data->tx_buf); 215 err_free_data: 216 kfree(data); 217 return err; 218 } 219 220 static int __devexit max1111_remove(struct spi_device *spi) 221 { 222 struct max1111_data *data = spi_get_drvdata(spi); 223 224 hwmon_device_unregister(data->hwmon_dev); 225 sysfs_remove_group(&spi->dev.kobj, &max1111_attr_group); 226 mutex_destroy(&data->drvdata_lock); 227 kfree(data->rx_buf); 228 kfree(data->tx_buf); 229 kfree(data); 230 return 0; 231 } 232 233 static struct spi_driver max1111_driver = { 234 .driver = { 235 .name = "max1111", 236 .owner = THIS_MODULE, 237 }, 238 .probe = max1111_probe, 239 .remove = __devexit_p(max1111_remove), 240 }; 241 242 static int __init max1111_init(void) 243 { 244 return spi_register_driver(&max1111_driver); 245 } 246 module_init(max1111_init); 247 248 static void __exit max1111_exit(void) 249 { 250 spi_unregister_driver(&max1111_driver); 251 } 252 module_exit(max1111_exit); 253 254 MODULE_AUTHOR("Eric Miao <eric.miao@marvell.com>"); 255 MODULE_DESCRIPTION("MAX1111 ADC Driver"); 256 MODULE_LICENSE("GPL"); 257 MODULE_ALIAS("spi:max1111"); 258