diff options
Diffstat (limited to 'drivers/iio/adc/nau7802.c')
-rw-r--r-- | drivers/iio/adc/nau7802.c | 581 |
1 files changed, 581 insertions, 0 deletions
diff --git a/drivers/iio/adc/nau7802.c b/drivers/iio/adc/nau7802.c new file mode 100644 index 0000000..bdf0346 --- /dev/null +++ b/drivers/iio/adc/nau7802.c @@ -0,0 +1,581 @@ +/* + * Driver for the Nuvoton NAU7802 ADC + * + * Copyright 2013 Free Electrons + * + * Licensed under the GPLv2 or later. + */ + +#include <linux/delay.h> +#include <linux/i2c.h> +#include <linux/interrupt.h> +#include <linux/module.h> +#include <linux/wait.h> +#include <linux/log2.h> + +#include <linux/iio/iio.h> +#include <linux/iio/sysfs.h> + +#define NAU7802_REG_PUCTRL 0x00 +#define NAU7802_PUCTRL_RR(x) (x << 0) +#define NAU7802_PUCTRL_RR_BIT NAU7802_PUCTRL_RR(1) +#define NAU7802_PUCTRL_PUD(x) (x << 1) +#define NAU7802_PUCTRL_PUD_BIT NAU7802_PUCTRL_PUD(1) +#define NAU7802_PUCTRL_PUA(x) (x << 2) +#define NAU7802_PUCTRL_PUA_BIT NAU7802_PUCTRL_PUA(1) +#define NAU7802_PUCTRL_PUR(x) (x << 3) +#define NAU7802_PUCTRL_PUR_BIT NAU7802_PUCTRL_PUR(1) +#define NAU7802_PUCTRL_CS(x) (x << 4) +#define NAU7802_PUCTRL_CS_BIT NAU7802_PUCTRL_CS(1) +#define NAU7802_PUCTRL_CR(x) (x << 5) +#define NAU7802_PUCTRL_CR_BIT NAU7802_PUCTRL_CR(1) +#define NAU7802_PUCTRL_AVDDS(x) (x << 7) +#define NAU7802_PUCTRL_AVDDS_BIT NAU7802_PUCTRL_AVDDS(1) +#define NAU7802_REG_CTRL1 0x01 +#define NAU7802_CTRL1_VLDO(x) (x << 3) +#define NAU7802_CTRL1_GAINS(x) (x) +#define NAU7802_CTRL1_GAINS_BITS 0x07 +#define NAU7802_REG_CTRL2 0x02 +#define NAU7802_CTRL2_CHS(x) (x << 7) +#define NAU7802_CTRL2_CRS(x) (x << 4) +#define NAU7802_SAMP_FREQ_320 0x07 +#define NAU7802_CTRL2_CHS_BIT NAU7802_CTRL2_CHS(1) +#define NAU7802_REG_ADC_B2 0x12 +#define NAU7802_REG_ADC_B1 0x13 +#define NAU7802_REG_ADC_B0 0x14 +#define NAU7802_REG_ADC_CTRL 0x15 + +#define NAU7802_MIN_CONVERSIONS 6 + +struct nau7802_state { + struct i2c_client *client; + s32 last_value; + struct mutex lock; + struct mutex data_lock; + u32 vref_mv; + u32 conversion_count; + u32 min_conversions; + u8 sample_rate; + u32 scale_avail[8]; + struct completion value_ok; +}; + +#define NAU7802_CHANNEL(chan) { \ + .type = IIO_VOLTAGE, \ + .indexed = 1, \ + .channel = (chan), \ + .scan_index = (chan), \ + .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \ + .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE) | \ + BIT(IIO_CHAN_INFO_SAMP_FREQ) \ +} + +static const struct iio_chan_spec nau7802_chan_array[] = { + NAU7802_CHANNEL(0), + NAU7802_CHANNEL(1), +}; + +static const u16 nau7802_sample_freq_avail[] = {10, 20, 40, 80, + 10, 10, 10, 320}; + +static IIO_CONST_ATTR_SAMP_FREQ_AVAIL("10 40 80 320"); + +static struct attribute *nau7802_attributes[] = { + &iio_const_attr_sampling_frequency_available.dev_attr.attr, + NULL +}; + +static const struct attribute_group nau7802_attribute_group = { + .attrs = nau7802_attributes, +}; + +static int nau7802_set_gain(struct nau7802_state *st, int gain) +{ + int ret; + + mutex_lock(&st->lock); + st->conversion_count = 0; + + ret = i2c_smbus_read_byte_data(st->client, NAU7802_REG_CTRL1); + if (ret < 0) + goto nau7802_sysfs_set_gain_out; + ret = i2c_smbus_write_byte_data(st->client, NAU7802_REG_CTRL1, + (ret & (~NAU7802_CTRL1_GAINS_BITS)) | + gain); + +nau7802_sysfs_set_gain_out: + mutex_unlock(&st->lock); + + return ret; +} + +static int nau7802_read_conversion(struct nau7802_state *st) +{ + int data; + + mutex_lock(&st->data_lock); + data = i2c_smbus_read_byte_data(st->client, NAU7802_REG_ADC_B2); + if (data < 0) + goto nau7802_read_conversion_out; + st->last_value = data << 16; + + data = i2c_smbus_read_byte_data(st->client, NAU7802_REG_ADC_B1); + if (data < 0) + goto nau7802_read_conversion_out; + st->last_value |= data << 8; + + data = i2c_smbus_read_byte_data(st->client, NAU7802_REG_ADC_B0); + if (data < 0) + goto nau7802_read_conversion_out; + st->last_value |= data; + + st->last_value = sign_extend32(st->last_value, 23); + +nau7802_read_conversion_out: + mutex_unlock(&st->data_lock); + + return data; +} + +/* + * Conversions are synchronised on the rising edge of NAU7802_PUCTRL_CS_BIT + */ +static int nau7802_sync(struct nau7802_state *st) +{ + int ret; + + ret = i2c_smbus_read_byte_data(st->client, NAU7802_REG_PUCTRL); + if (ret < 0) + return ret; + ret = i2c_smbus_write_byte_data(st->client, NAU7802_REG_PUCTRL, + ret | NAU7802_PUCTRL_CS_BIT); + + return ret; +} + +static irqreturn_t nau7802_eoc_trigger(int irq, void *private) +{ + struct iio_dev *indio_dev = private; + struct nau7802_state *st = iio_priv(indio_dev); + int status; + + status = i2c_smbus_read_byte_data(st->client, NAU7802_REG_PUCTRL); + if (status < 0) + return IRQ_HANDLED; + + if (!(status & NAU7802_PUCTRL_CR_BIT)) + return IRQ_NONE; + + if (nau7802_read_conversion(st) < 0) + return IRQ_HANDLED; + + /* + * Because there is actually only one ADC for both channels, we have to + * wait for enough conversions to happen before getting a significant + * value when changing channels and the values are far apart. + */ + if (st->conversion_count < NAU7802_MIN_CONVERSIONS) + st->conversion_count++; + if (st->conversion_count >= NAU7802_MIN_CONVERSIONS) + complete_all(&st->value_ok); + + return IRQ_HANDLED; +} + +static int nau7802_read_irq(struct iio_dev *indio_dev, + struct iio_chan_spec const *chan, + int *val) +{ + struct nau7802_state *st = iio_priv(indio_dev); + int ret; + + INIT_COMPLETION(st->value_ok); + enable_irq(st->client->irq); + + nau7802_sync(st); + + /* read registers to ensure we flush everything */ + ret = nau7802_read_conversion(st); + if (ret < 0) + goto read_chan_info_failure; + + /* Wait for a conversion to finish */ + ret = wait_for_completion_interruptible_timeout(&st->value_ok, + msecs_to_jiffies(1000)); + if (ret == 0) + ret = -ETIMEDOUT; + + if (ret < 0) + goto read_chan_info_failure; + + disable_irq(st->client->irq); + + *val = st->last_value; + + return IIO_VAL_INT; + +read_chan_info_failure: + disable_irq(st->client->irq); + + return ret; +} + +static int nau7802_read_poll(struct iio_dev *indio_dev, + struct iio_chan_spec const *chan, + int *val) +{ + struct nau7802_state *st = iio_priv(indio_dev); + int ret; + + nau7802_sync(st); + + /* read registers to ensure we flush everything */ + ret = nau7802_read_conversion(st); + if (ret < 0) + return ret; + + /* + * Because there is actually only one ADC for both channels, we have to + * wait for enough conversions to happen before getting a significant + * value when changing channels and the values are far appart. + */ + do { + ret = i2c_smbus_read_byte_data(st->client, NAU7802_REG_PUCTRL); + if (ret < 0) + return ret; + + while (!(ret & NAU7802_PUCTRL_CR_BIT)) { + if (st->sample_rate != NAU7802_SAMP_FREQ_320) + msleep(20); + else + mdelay(4); + ret = i2c_smbus_read_byte_data(st->client, + NAU7802_REG_PUCTRL); + if (ret < 0) + return ret; + } + + ret = nau7802_read_conversion(st); + if (ret < 0) + return ret; + if (st->conversion_count < NAU7802_MIN_CONVERSIONS) + st->conversion_count++; + } while (st->conversion_count < NAU7802_MIN_CONVERSIONS); + + *val = st->last_value; + + return IIO_VAL_INT; +} + +static int nau7802_read_raw(struct iio_dev *indio_dev, + struct iio_chan_spec const *chan, + int *val, int *val2, long mask) +{ + struct nau7802_state *st = iio_priv(indio_dev); + int ret; + + switch (mask) { + case IIO_CHAN_INFO_RAW: + mutex_lock(&st->lock); + /* + * Select the channel to use + * - Channel 1 is value 0 in the CHS register + * - Channel 2 is value 1 in the CHS register + */ + ret = i2c_smbus_read_byte_data(st->client, NAU7802_REG_CTRL2); + if (ret < 0) { + mutex_unlock(&st->lock); + return ret; + } + + if (((ret & NAU7802_CTRL2_CHS_BIT) && !chan->channel) || + (!(ret & NAU7802_CTRL2_CHS_BIT) && + chan->channel)) { + st->conversion_count = 0; + ret = i2c_smbus_write_byte_data(st->client, + NAU7802_REG_CTRL2, + NAU7802_CTRL2_CHS(chan->channel) | + NAU7802_CTRL2_CRS(st->sample_rate)); + + if (ret < 0) { + mutex_unlock(&st->lock); + return ret; + } + } + + if (st->client->irq) + ret = nau7802_read_irq(indio_dev, chan, val); + else + ret = nau7802_read_poll(indio_dev, chan, val); + + mutex_unlock(&st->lock); + return ret; + + case IIO_CHAN_INFO_SCALE: + ret = i2c_smbus_read_byte_data(st->client, NAU7802_REG_CTRL1); + if (ret < 0) + return ret; + + /* + * We have 24 bits of signed data, that means 23 bits of data + * plus the sign bit + */ + *val = st->vref_mv; + *val2 = 23 + (ret & NAU7802_CTRL1_GAINS_BITS); + + return IIO_VAL_FRACTIONAL_LOG2; + + case IIO_CHAN_INFO_SAMP_FREQ: + *val = nau7802_sample_freq_avail[st->sample_rate]; + *val2 = 0; + return IIO_VAL_INT; + + default: + break; + } + + return -EINVAL; +} + +static int nau7802_write_raw(struct iio_dev *indio_dev, + struct iio_chan_spec const *chan, + int val, int val2, long mask) +{ + struct nau7802_state *st = iio_priv(indio_dev); + int i, ret; + + switch (mask) { + case IIO_CHAN_INFO_SCALE: + for (i = 0; i < ARRAY_SIZE(st->scale_avail); i++) + if (val2 == st->scale_avail[i]) + return nau7802_set_gain(st, i); + + break; + + case IIO_CHAN_INFO_SAMP_FREQ: + for (i = 0; i < ARRAY_SIZE(nau7802_sample_freq_avail); i++) + if (val == nau7802_sample_freq_avail[i]) { + mutex_lock(&st->lock); + st->sample_rate = i; + st->conversion_count = 0; + ret = i2c_smbus_write_byte_data(st->client, + NAU7802_REG_CTRL2, + NAU7802_CTRL2_CRS(st->sample_rate)); + mutex_unlock(&st->lock); + return ret; + } + + break; + + default: + break; + } + + return -EINVAL; +} + +static int nau7802_write_raw_get_fmt(struct iio_dev *indio_dev, + struct iio_chan_spec const *chan, + long mask) +{ + return IIO_VAL_INT_PLUS_NANO; +} + +static const struct iio_info nau7802_info = { + .driver_module = THIS_MODULE, + .read_raw = &nau7802_read_raw, + .write_raw = &nau7802_write_raw, + .write_raw_get_fmt = nau7802_write_raw_get_fmt, + .attrs = &nau7802_attribute_group, +}; + +static int nau7802_probe(struct i2c_client *client, + const struct i2c_device_id *id) +{ + struct iio_dev *indio_dev; + struct nau7802_state *st; + struct device_node *np = client->dev.of_node; + int i, ret; + u8 data; + u32 tmp = 0; + + if (!client->dev.of_node) { + dev_err(&client->dev, "No device tree node available.\n"); + return -EINVAL; + } + + indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*st)); + if (indio_dev == NULL) + return -ENOMEM; + + st = iio_priv(indio_dev); + + i2c_set_clientdata(client, indio_dev); + + indio_dev->dev.parent = &client->dev; + indio_dev->name = dev_name(&client->dev); + indio_dev->modes = INDIO_DIRECT_MODE; + indio_dev->info = &nau7802_info; + + st->client = client; + + /* Reset the device */ + ret = i2c_smbus_write_byte_data(st->client, NAU7802_REG_PUCTRL, + NAU7802_PUCTRL_RR_BIT); + if (ret < 0) + return ret; + + /* Enter normal operation mode */ + ret = i2c_smbus_write_byte_data(st->client, NAU7802_REG_PUCTRL, + NAU7802_PUCTRL_PUD_BIT); + if (ret < 0) + return ret; + + /* + * After about 200 usecs, the device should be ready and then + * the Power Up bit will be set to 1. If not, wait for it. + */ + udelay(210); + ret = i2c_smbus_read_byte_data(st->client, NAU7802_REG_PUCTRL); + if (ret < 0) + return ret; + if (!(ret & NAU7802_PUCTRL_PUR_BIT)) + return ret; + + of_property_read_u32(np, "nuvoton,vldo", &tmp); + st->vref_mv = tmp; + + data = NAU7802_PUCTRL_PUD_BIT | NAU7802_PUCTRL_PUA_BIT | + NAU7802_PUCTRL_CS_BIT; + if (tmp >= 2400) + data |= NAU7802_PUCTRL_AVDDS_BIT; + + ret = i2c_smbus_write_byte_data(st->client, NAU7802_REG_PUCTRL, data); + if (ret < 0) + return ret; + ret = i2c_smbus_write_byte_data(st->client, NAU7802_REG_ADC_CTRL, 0x30); + if (ret < 0) + return ret; + + if (tmp >= 2400) { + data = NAU7802_CTRL1_VLDO((4500 - tmp) / 300); + ret = i2c_smbus_write_byte_data(st->client, NAU7802_REG_CTRL1, + data); + if (ret < 0) + return ret; + } + + /* Populate available ADC input ranges */ + for (i = 0; i < ARRAY_SIZE(st->scale_avail); i++) + st->scale_avail[i] = (((u64)st->vref_mv) * 1000000000ULL) + >> (23 + i); + + init_completion(&st->value_ok); + + /* + * The ADC fires continuously and we can't do anything about + * it. So we need to have the IRQ disabled by default, and we + * will enable them back when we will need them.. + */ + if (client->irq) { + ret = request_threaded_irq(client->irq, + NULL, + nau7802_eoc_trigger, + IRQF_TRIGGER_HIGH | IRQF_ONESHOT, + client->dev.driver->name, + indio_dev); + if (ret) { + /* + * What may happen here is that our IRQ controller is + * not able to get level interrupt but this is required + * by this ADC as when going over 40 sample per second, + * the interrupt line may stay high between conversions. + * So, we continue no matter what but we switch to + * polling mode. + */ + dev_info(&client->dev, + "Failed to allocate IRQ, using polling mode\n"); + client->irq = 0; + } else + disable_irq(client->irq); + } + + if (!client->irq) { + /* + * We are polling, use the fastest sample rate by + * default + */ + st->sample_rate = NAU7802_SAMP_FREQ_320; + ret = i2c_smbus_write_byte_data(st->client, NAU7802_REG_CTRL2, + NAU7802_CTRL2_CRS(st->sample_rate)); + if (ret) + goto error_free_irq; + } + + /* Setup the ADC channels available on the board */ + indio_dev->num_channels = ARRAY_SIZE(nau7802_chan_array); + indio_dev->channels = nau7802_chan_array; + + mutex_init(&st->lock); + mutex_init(&st->data_lock); + + ret = iio_device_register(indio_dev); + if (ret < 0) { + dev_err(&client->dev, "Couldn't register the device.\n"); + goto error_device_register; + } + + return 0; + +error_device_register: + mutex_destroy(&st->lock); + mutex_destroy(&st->data_lock); +error_free_irq: + if (client->irq) + free_irq(client->irq, indio_dev); + + return ret; +} + +static int nau7802_remove(struct i2c_client *client) +{ + struct iio_dev *indio_dev = i2c_get_clientdata(client); + struct nau7802_state *st = iio_priv(indio_dev); + + iio_device_unregister(indio_dev); + mutex_destroy(&st->lock); + mutex_destroy(&st->data_lock); + if (client->irq) + free_irq(client->irq, indio_dev); + + return 0; +} + +static const struct i2c_device_id nau7802_i2c_id[] = { + { "nau7802", 0 }, + { } +}; +MODULE_DEVICE_TABLE(i2c, nau7802_i2c_id); + +static const struct of_device_id nau7802_dt_ids[] = { + { .compatible = "nuvoton,nau7802" }, + {}, +}; +MODULE_DEVICE_TABLE(of, nau7802_dt_ids); + +static struct i2c_driver nau7802_driver = { + .probe = nau7802_probe, + .remove = nau7802_remove, + .id_table = nau7802_i2c_id, + .driver = { + .name = "nau7802", + .of_match_table = of_match_ptr(nau7802_dt_ids), + }, +}; + +module_i2c_driver(nau7802_driver); + +MODULE_LICENSE("GPL"); +MODULE_DESCRIPTION("Nuvoton NAU7802 ADC Driver"); +MODULE_AUTHOR("Maxime Ripard <maxime.ripard@free-electrons.com>"); +MODULE_AUTHOR("Alexandre Belloni <alexandre.belloni@free-electrons.com>"); |