// SPDX-License-Identifier: GPL-2.0-or-later /* * ads7871 - driver for TI ADS7871 A/D converter * * Copyright (c) 2010 Paul Thomas * * You need to have something like this in struct spi_board_info * { * .modalias = "ads7871", * .max_speed_hz = 2*1000*1000, * .chip_select = 0, * .bus_num = 1, * }, */ /*From figure 18 in the datasheet*/ /*Register addresses*/ #define REG_LS_BYTE 0 /*A/D Output Data, LS Byte*/ #define REG_MS_BYTE 1 /*A/D Output Data, MS Byte*/ #define REG_PGA_VALID 2 /*PGA Valid Register*/ #define REG_AD_CONTROL 3 /*A/D Control Register*/ #define REG_GAIN_MUX 4 /*Gain/Mux Register*/ #define REG_IO_STATE 5 /*Digital I/O State Register*/ #define REG_IO_CONTROL 6 /*Digital I/O Control Register*/ #define REG_OSC_CONTROL 7 /*Rev/Oscillator Control Register*/ #define REG_SER_CONTROL 24 /*Serial Interface Control Register*/ #define REG_ID 31 /*ID Register*/ /* * From figure 17 in the datasheet * These bits get ORed with the address to form * the instruction byte */ /*Instruction Bit masks*/ #define INST_MODE_BM (1 << 7) #define INST_READ_BM (1 << 6) #define INST_16BIT_BM (1 << 5) /*From figure 18 in the datasheet*/ /*bit masks for Rev/Oscillator Control Register*/ #define MUX_CNV_BV 7 #define MUX_CNV_BM (1 << MUX_CNV_BV) #define MUX_M3_BM (1 << 3) /*M3 selects single ended*/ #define MUX_G_BV 4 /*allows for reg = (gain << MUX_G_BV) | ...*/ /*From figure 18 in the datasheet*/ /*bit masks for Rev/Oscillator Control Register*/ #define OSC_OSCR_BM (1 << 5) #define OSC_OSCE_BM (1 << 4) #define OSC_REFE_BM (1 << 3) #define OSC_BUFE_BM (1 << 2) #define OSC_R2V_BM (1 << 1) #define OSC_RBG_BM (1 << 0) #include #include #include #include #include #include #define DEVICE_NAME "ads7871" struct ads7871_data { struct spi_device *spi; u8 tx_buf[2] ____cacheline_aligned; }; static umode_t ads7871_is_visible(const void *data, enum hwmon_sensor_types type, u32 attr, int channel) { if (type == hwmon_in && attr == hwmon_in_input) return 0444; return 0; } static int ads7871_read_reg8(struct spi_device *spi, int reg) { int ret; reg = reg | INST_READ_BM; ret = spi_w8r8(spi, reg); return ret; } static int ads7871_read_reg16(struct spi_device *spi, int reg) { int ret; reg = reg | INST_READ_BM | INST_16BIT_BM; ret = spi_w8r16(spi, reg); if (ret < 0) return ret; return le16_to_cpu((__force __le16)ret); } static int ads7871_write_reg8(struct ads7871_data *pdata, int reg, u8 val) { pdata->tx_buf[0] = reg; pdata->tx_buf[1] = val; return spi_write(pdata->spi, pdata->tx_buf, 2); } static int ads7871_read(struct device *dev, enum hwmon_sensor_types type, u32 attr, int channel, long *val) { struct ads7871_data *pdata = dev_get_drvdata(dev); struct spi_device *spi = pdata->spi; int ret, raw_val, i = 0; u8 mux_cnv; if (type != hwmon_in || attr != hwmon_in_input) return -EOPNOTSUPP; /* * TODO: add support for conversions * other than single ended with a gain of 1 */ /*MUX_M3_BM forces single ended*/ /*This is also where the gain of the PGA would be set*/ ret = ads7871_write_reg8(pdata, REG_GAIN_MUX, (MUX_CNV_BM | MUX_M3_BM | channel)); if (ret < 0) return ret; ret = ads7871_read_reg8(spi, REG_GAIN_MUX); if (ret < 0) return ret; mux_cnv = ((ret & MUX_CNV_BM) >> MUX_CNV_BV); /* * on 400MHz arm9 platform the conversion * is already done when we do this test */ while ((i < 2) && mux_cnv) { i++; ret = ads7871_read_reg8(spi, REG_GAIN_MUX); if (ret < 0) return ret; mux_cnv = ((ret & MUX_CNV_BM) >> MUX_CNV_BV); msleep_interruptible(1); } if (mux_cnv == 0) { raw_val = ads7871_read_reg16(spi, REG_LS_BYTE); if (raw_val < 0) return raw_val; /* * Use (s16) to ensure the sign bit is preserved during the shift. * Report millivolts (2.5V = 2500mV). */ *val = ((s16)raw_val >> 2) * 2500 / 8192; return 0; } return -ETIMEDOUT; } static const struct hwmon_channel_info * const ads7871_info[] = { HWMON_CHANNEL_INFO(in, HWMON_I_INPUT, HWMON_I_INPUT, HWMON_I_INPUT, HWMON_I_INPUT, HWMON_I_INPUT, HWMON_I_INPUT, HWMON_I_INPUT, HWMON_I_INPUT), NULL }; static const struct hwmon_ops ads7871_hwmon_ops = { .is_visible = ads7871_is_visible, .read = ads7871_read, }; static const struct hwmon_chip_info ads7871_chip_info = { .ops = &ads7871_hwmon_ops, .info = ads7871_info, }; static int ads7871_probe(struct spi_device *spi) { struct device *dev = &spi->dev; int ret; uint8_t val; struct ads7871_data *pdata; struct device *hwmon_dev; /* Configure the SPI bus */ spi->mode = (SPI_MODE_0); spi->bits_per_word = 8; spi_setup(spi); pdata = devm_kzalloc(dev, sizeof(*pdata), GFP_KERNEL); if (!pdata) return -ENOMEM; pdata->spi = spi; ads7871_write_reg8(pdata, REG_SER_CONTROL, 0); ads7871_write_reg8(pdata, REG_AD_CONTROL, 0); val = (OSC_OSCR_BM | OSC_OSCE_BM | OSC_REFE_BM | OSC_BUFE_BM); ads7871_write_reg8(pdata, REG_OSC_CONTROL, val); ret = ads7871_read_reg8(spi, REG_OSC_CONTROL); dev_dbg(dev, "REG_OSC_CONTROL write:%x, read:%x\n", val, ret); /* * because there is no other error checking on an SPI bus * we need to make sure we really have a chip */ if (val != ret) return -ENODEV; hwmon_dev = devm_hwmon_device_register_with_info(dev, spi->modalias, pdata, &ads7871_chip_info, NULL); return PTR_ERR_OR_ZERO(hwmon_dev); } static struct spi_driver ads7871_driver = { .driver = { .name = DEVICE_NAME, }, .probe = ads7871_probe, }; module_spi_driver(ads7871_driver); MODULE_AUTHOR("Paul Thomas "); MODULE_DESCRIPTION("TI ADS7871 A/D driver"); MODULE_LICENSE("GPL");