Paul Thomas | e0c70b8 | 2010-05-24 14:33:38 -0700 | [diff] [blame] | 1 | /* |
| 2 | * ads7871 - driver for TI ADS7871 A/D converter |
| 3 | * |
| 4 | * Copyright (c) 2010 Paul Thomas <pthomas8589@gmail.com> |
| 5 | * |
| 6 | * This program is distributed in the hope that it will be useful, |
| 7 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 8 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 9 | * GNU General Public License for more details. |
| 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 or |
| 13 | * later as publishhed by the Free Software Foundation. |
| 14 | * |
| 15 | * You need to have something like this in struct spi_board_info |
| 16 | * { |
| 17 | * .modalias = "ads7871", |
| 18 | * .max_speed_hz = 2*1000*1000, |
| 19 | * .chip_select = 0, |
| 20 | * .bus_num = 1, |
| 21 | * }, |
| 22 | */ |
| 23 | |
| 24 | /*From figure 18 in the datasheet*/ |
| 25 | /*Register addresses*/ |
| 26 | #define REG_LS_BYTE 0 /*A/D Output Data, LS Byte*/ |
| 27 | #define REG_MS_BYTE 1 /*A/D Output Data, MS Byte*/ |
| 28 | #define REG_PGA_VALID 2 /*PGA Valid Register*/ |
| 29 | #define REG_AD_CONTROL 3 /*A/D Control Register*/ |
| 30 | #define REG_GAIN_MUX 4 /*Gain/Mux Register*/ |
| 31 | #define REG_IO_STATE 5 /*Digital I/O State Register*/ |
| 32 | #define REG_IO_CONTROL 6 /*Digital I/O Control Register*/ |
| 33 | #define REG_OSC_CONTROL 7 /*Rev/Oscillator Control Register*/ |
| 34 | #define REG_SER_CONTROL 24 /*Serial Interface Control Register*/ |
| 35 | #define REG_ID 31 /*ID Register*/ |
| 36 | |
| 37 | /*From figure 17 in the datasheet |
| 38 | * These bits get ORed with the address to form |
| 39 | * the instruction byte */ |
| 40 | /*Instruction Bit masks*/ |
| 41 | #define INST_MODE_bm (1<<7) |
| 42 | #define INST_READ_bm (1<<6) |
| 43 | #define INST_16BIT_bm (1<<5) |
| 44 | |
| 45 | /*From figure 18 in the datasheet*/ |
| 46 | /*bit masks for Rev/Oscillator Control Register*/ |
| 47 | #define MUX_CNV_bv 7 |
| 48 | #define MUX_CNV_bm (1<<MUX_CNV_bv) |
| 49 | #define MUX_M3_bm (1<<3) /*M3 selects single ended*/ |
| 50 | #define MUX_G_bv 4 /*allows for reg = (gain << MUX_G_bv) | ...*/ |
| 51 | |
| 52 | /*From figure 18 in the datasheet*/ |
| 53 | /*bit masks for Rev/Oscillator Control Register*/ |
| 54 | #define OSC_OSCR_bm (1<<5) |
| 55 | #define OSC_OSCE_bm (1<<4) |
| 56 | #define OSC_REFE_bm (1<<3) |
| 57 | #define OSC_BUFE_bm (1<<2) |
| 58 | #define OSC_R2V_bm (1<<1) |
| 59 | #define OSC_RBG_bm (1<<0) |
| 60 | |
| 61 | #include <linux/module.h> |
| 62 | #include <linux/init.h> |
| 63 | #include <linux/spi/spi.h> |
| 64 | #include <linux/hwmon.h> |
| 65 | #include <linux/hwmon-sysfs.h> |
| 66 | #include <linux/err.h> |
| 67 | #include <linux/mutex.h> |
| 68 | #include <linux/delay.h> |
| 69 | |
| 70 | #define DEVICE_NAME "ads7871" |
| 71 | |
| 72 | struct ads7871_data { |
| 73 | struct device *hwmon_dev; |
| 74 | struct mutex update_lock; |
| 75 | }; |
| 76 | |
| 77 | static int ads7871_read_reg8(struct spi_device *spi, int reg) |
| 78 | { |
| 79 | int ret; |
| 80 | reg = reg | INST_READ_bm; |
| 81 | ret = spi_w8r8(spi, reg); |
| 82 | return ret; |
| 83 | } |
| 84 | |
| 85 | static int ads7871_read_reg16(struct spi_device *spi, int reg) |
| 86 | { |
| 87 | int ret; |
| 88 | reg = reg | INST_READ_bm | INST_16BIT_bm; |
| 89 | ret = spi_w8r16(spi, reg); |
| 90 | return ret; |
| 91 | } |
| 92 | |
| 93 | static int ads7871_write_reg8(struct spi_device *spi, int reg, u8 val) |
| 94 | { |
| 95 | u8 tmp[2] = {reg, val}; |
| 96 | return spi_write(spi, tmp, sizeof(tmp)); |
| 97 | } |
| 98 | |
| 99 | static ssize_t show_voltage(struct device *dev, |
| 100 | struct device_attribute *da, char *buf) |
| 101 | { |
| 102 | struct spi_device *spi = to_spi_device(dev); |
| 103 | struct sensor_device_attribute *attr = to_sensor_dev_attr(da); |
| 104 | int ret, val, i = 0; |
| 105 | uint8_t channel, mux_cnv; |
| 106 | |
| 107 | channel = attr->index; |
| 108 | /*TODO: add support for conversions |
| 109 | *other than single ended with a gain of 1*/ |
| 110 | /*MUX_M3_bm forces single ended*/ |
| 111 | /*This is also where the gain of the PGA would be set*/ |
| 112 | ads7871_write_reg8(spi, REG_GAIN_MUX, |
| 113 | (MUX_CNV_bm | MUX_M3_bm | channel)); |
| 114 | |
| 115 | ret = ads7871_read_reg8(spi, REG_GAIN_MUX); |
| 116 | mux_cnv = ((ret & MUX_CNV_bm)>>MUX_CNV_bv); |
| 117 | /*on 400MHz arm9 platform the conversion |
| 118 | *is already done when we do this test*/ |
| 119 | while ((i < 2) && mux_cnv) { |
| 120 | i++; |
| 121 | ret = ads7871_read_reg8(spi, REG_GAIN_MUX); |
| 122 | mux_cnv = ((ret & MUX_CNV_bm)>>MUX_CNV_bv); |
| 123 | msleep_interruptible(1); |
| 124 | } |
| 125 | |
| 126 | if (mux_cnv == 0) { |
| 127 | val = ads7871_read_reg16(spi, REG_LS_BYTE); |
| 128 | /*result in volts*10000 = (val/8192)*2.5*10000*/ |
| 129 | val = ((val>>2) * 25000) / 8192; |
| 130 | return sprintf(buf, "%d\n", val); |
| 131 | } else { |
| 132 | return -1; |
| 133 | } |
| 134 | } |
| 135 | |
| 136 | static SENSOR_DEVICE_ATTR(in0_input, S_IRUGO, show_voltage, NULL, 0); |
| 137 | static SENSOR_DEVICE_ATTR(in1_input, S_IRUGO, show_voltage, NULL, 1); |
| 138 | static SENSOR_DEVICE_ATTR(in2_input, S_IRUGO, show_voltage, NULL, 2); |
| 139 | static SENSOR_DEVICE_ATTR(in3_input, S_IRUGO, show_voltage, NULL, 3); |
| 140 | static SENSOR_DEVICE_ATTR(in4_input, S_IRUGO, show_voltage, NULL, 4); |
| 141 | static SENSOR_DEVICE_ATTR(in5_input, S_IRUGO, show_voltage, NULL, 5); |
| 142 | static SENSOR_DEVICE_ATTR(in6_input, S_IRUGO, show_voltage, NULL, 6); |
| 143 | static SENSOR_DEVICE_ATTR(in7_input, S_IRUGO, show_voltage, NULL, 7); |
| 144 | |
| 145 | static struct attribute *ads7871_attributes[] = { |
| 146 | &sensor_dev_attr_in0_input.dev_attr.attr, |
| 147 | &sensor_dev_attr_in1_input.dev_attr.attr, |
| 148 | &sensor_dev_attr_in2_input.dev_attr.attr, |
| 149 | &sensor_dev_attr_in3_input.dev_attr.attr, |
| 150 | &sensor_dev_attr_in4_input.dev_attr.attr, |
| 151 | &sensor_dev_attr_in5_input.dev_attr.attr, |
| 152 | &sensor_dev_attr_in6_input.dev_attr.attr, |
| 153 | &sensor_dev_attr_in7_input.dev_attr.attr, |
| 154 | NULL |
| 155 | }; |
| 156 | |
| 157 | static const struct attribute_group ads7871_group = { |
| 158 | .attrs = ads7871_attributes, |
| 159 | }; |
| 160 | |
| 161 | static int __devinit ads7871_probe(struct spi_device *spi) |
| 162 | { |
Axel Lin | c12c507 | 2010-08-25 15:42:10 +0200 | [diff] [blame] | 163 | int ret, err; |
Paul Thomas | e0c70b8 | 2010-05-24 14:33:38 -0700 | [diff] [blame] | 164 | uint8_t val; |
| 165 | struct ads7871_data *pdata; |
| 166 | |
| 167 | dev_dbg(&spi->dev, "probe\n"); |
| 168 | |
Paul Thomas | e0c70b8 | 2010-05-24 14:33:38 -0700 | [diff] [blame] | 169 | /* Configure the SPI bus */ |
| 170 | spi->mode = (SPI_MODE_0); |
| 171 | spi->bits_per_word = 8; |
| 172 | spi_setup(spi); |
| 173 | |
| 174 | ads7871_write_reg8(spi, REG_SER_CONTROL, 0); |
| 175 | ads7871_write_reg8(spi, REG_AD_CONTROL, 0); |
| 176 | |
| 177 | val = (OSC_OSCR_bm | OSC_OSCE_bm | OSC_REFE_bm | OSC_BUFE_bm); |
| 178 | ads7871_write_reg8(spi, REG_OSC_CONTROL, val); |
| 179 | ret = ads7871_read_reg8(spi, REG_OSC_CONTROL); |
| 180 | |
| 181 | dev_dbg(&spi->dev, "REG_OSC_CONTROL write:%x, read:%x\n", val, ret); |
| 182 | /*because there is no other error checking on an SPI bus |
| 183 | we need to make sure we really have a chip*/ |
| 184 | if (val != ret) { |
| 185 | err = -ENODEV; |
Axel Lin | c12c507 | 2010-08-25 15:42:10 +0200 | [diff] [blame] | 186 | goto exit; |
| 187 | } |
| 188 | |
| 189 | pdata = kzalloc(sizeof(struct ads7871_data), GFP_KERNEL); |
| 190 | if (!pdata) { |
| 191 | err = -ENOMEM; |
| 192 | goto exit; |
| 193 | } |
| 194 | |
| 195 | err = sysfs_create_group(&spi->dev.kobj, &ads7871_group); |
| 196 | if (err < 0) |
| 197 | goto error_free; |
| 198 | |
| 199 | spi_set_drvdata(spi, pdata); |
| 200 | |
| 201 | pdata->hwmon_dev = hwmon_device_register(&spi->dev); |
| 202 | if (IS_ERR(pdata->hwmon_dev)) { |
| 203 | err = PTR_ERR(pdata->hwmon_dev); |
Paul Thomas | e0c70b8 | 2010-05-24 14:33:38 -0700 | [diff] [blame] | 204 | goto error_remove; |
| 205 | } |
| 206 | |
| 207 | return 0; |
| 208 | |
| 209 | error_remove: |
| 210 | sysfs_remove_group(&spi->dev.kobj, &ads7871_group); |
| 211 | error_free: |
| 212 | kfree(pdata); |
| 213 | exit: |
| 214 | return err; |
| 215 | } |
| 216 | |
| 217 | static int __devexit ads7871_remove(struct spi_device *spi) |
| 218 | { |
| 219 | struct ads7871_data *pdata = spi_get_drvdata(spi); |
| 220 | |
| 221 | hwmon_device_unregister(pdata->hwmon_dev); |
| 222 | sysfs_remove_group(&spi->dev.kobj, &ads7871_group); |
| 223 | kfree(pdata); |
| 224 | return 0; |
| 225 | } |
| 226 | |
| 227 | static struct spi_driver ads7871_driver = { |
| 228 | .driver = { |
| 229 | .name = DEVICE_NAME, |
Paul Thomas | e0c70b8 | 2010-05-24 14:33:38 -0700 | [diff] [blame] | 230 | .owner = THIS_MODULE, |
| 231 | }, |
| 232 | |
| 233 | .probe = ads7871_probe, |
| 234 | .remove = __devexit_p(ads7871_remove), |
| 235 | }; |
| 236 | |
| 237 | static int __init ads7871_init(void) |
| 238 | { |
| 239 | return spi_register_driver(&ads7871_driver); |
| 240 | } |
| 241 | |
| 242 | static void __exit ads7871_exit(void) |
| 243 | { |
| 244 | spi_unregister_driver(&ads7871_driver); |
| 245 | } |
| 246 | |
| 247 | module_init(ads7871_init); |
| 248 | module_exit(ads7871_exit); |
| 249 | |
| 250 | MODULE_AUTHOR("Paul Thomas <pthomas8589@gmail.com>"); |
| 251 | MODULE_DESCRIPTION("TI ADS7871 A/D driver"); |
| 252 | MODULE_LICENSE("GPL"); |