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 /* 110 * assume the reference voltage to be 2.048V, with an 8-bit sample, 111 * the LSB weight is 8mV 112 */ 113 return sprintf(buf, "%d\n", ret * 8); 114 } 115 116 #define MAX1111_ADC_ATTR(_id) \ 117 SENSOR_DEVICE_ATTR(in##_id##_input, S_IRUGO, show_adc, NULL, _id) 118 119 static DEVICE_ATTR(name, S_IRUGO, show_name, NULL); 120 static MAX1111_ADC_ATTR(0); 121 static MAX1111_ADC_ATTR(1); 122 static MAX1111_ADC_ATTR(2); 123 static MAX1111_ADC_ATTR(3); 124 125 static struct attribute *max1111_attributes[] = { 126 &dev_attr_name.attr, 127 &sensor_dev_attr_in0_input.dev_attr.attr, 128 &sensor_dev_attr_in1_input.dev_attr.attr, 129 &sensor_dev_attr_in2_input.dev_attr.attr, 130 &sensor_dev_attr_in3_input.dev_attr.attr, 131 NULL, 132 }; 133 134 static const struct attribute_group max1111_attr_group = { 135 .attrs = max1111_attributes, 136 }; 137 138 static int __devinit setup_transfer(struct max1111_data *data) 139 { 140 struct spi_message *m; 141 struct spi_transfer *x; 142 143 m = &data->msg; 144 x = &data->xfer[0]; 145 146 spi_message_init(m); 147 148 x->tx_buf = &data->tx_buf[0]; 149 x->len = MAX1111_TX_BUF_SIZE; 150 spi_message_add_tail(x, m); 151 152 x++; 153 x->rx_buf = &data->rx_buf[0]; 154 x->len = MAX1111_RX_BUF_SIZE; 155 spi_message_add_tail(x, m); 156 157 return 0; 158 } 159 160 static int __devinit max1111_probe(struct spi_device *spi) 161 { 162 struct max1111_data *data; 163 int err; 164 165 spi->bits_per_word = 8; 166 spi->mode = SPI_MODE_0; 167 err = spi_setup(spi); 168 if (err < 0) 169 return err; 170 171 data = devm_kzalloc(&spi->dev, sizeof(struct max1111_data), GFP_KERNEL); 172 if (data == NULL) { 173 dev_err(&spi->dev, "failed to allocate memory\n"); 174 return -ENOMEM; 175 } 176 177 err = setup_transfer(data); 178 if (err) 179 return err; 180 181 mutex_init(&data->drvdata_lock); 182 183 data->spi = spi; 184 spi_set_drvdata(spi, data); 185 186 err = sysfs_create_group(&spi->dev.kobj, &max1111_attr_group); 187 if (err) { 188 dev_err(&spi->dev, "failed to create attribute group\n"); 189 return err; 190 } 191 192 data->hwmon_dev = hwmon_device_register(&spi->dev); 193 if (IS_ERR(data->hwmon_dev)) { 194 dev_err(&spi->dev, "failed to create hwmon device\n"); 195 err = PTR_ERR(data->hwmon_dev); 196 goto err_remove; 197 } 198 199 #ifdef CONFIG_SHARPSL_PM 200 the_max1111 = data; 201 #endif 202 return 0; 203 204 err_remove: 205 sysfs_remove_group(&spi->dev.kobj, &max1111_attr_group); 206 return err; 207 } 208 209 static int __devexit max1111_remove(struct spi_device *spi) 210 { 211 struct max1111_data *data = spi_get_drvdata(spi); 212 213 hwmon_device_unregister(data->hwmon_dev); 214 sysfs_remove_group(&spi->dev.kobj, &max1111_attr_group); 215 mutex_destroy(&data->drvdata_lock); 216 return 0; 217 } 218 219 static struct spi_driver max1111_driver = { 220 .driver = { 221 .name = "max1111", 222 .owner = THIS_MODULE, 223 }, 224 .probe = max1111_probe, 225 .remove = __devexit_p(max1111_remove), 226 }; 227 228 module_spi_driver(max1111_driver); 229 230 MODULE_AUTHOR("Eric Miao <eric.miao@marvell.com>"); 231 MODULE_DESCRIPTION("MAX1111 ADC Driver"); 232 MODULE_LICENSE("GPL"); 233 MODULE_ALIAS("spi:max1111"); 234