On 06/12/14 11:36, Hartmut Knaack wrote:
> Nikolaus Schulz schrieb am 24.11.2014 um 20:50:
>> The TI DAC8554 is a quad-channel Digital-to-Analog Converter with an SPI
>> interface.
>>
>> Changes in v2:
>> * Use DMA-safe buffer for SPI transfer
>> * Normalize powerdown_mode name "hi-z" to "three_state" as per
>> ABI/testing/sysfs-bus-iio
>> * Register device late in probe function
>> * Avoid powerdown broadcast update, which touches all DAC on the bus
> There are a few issues left, please see my comments inline.
1 little one from me...
>>
>> Signed-off-by: Nikolaus Schulz <nikolaus.schulz@xxxxxxxxxxxxxxxxx>
>> ---
>> drivers/iio/dac/Kconfig | 10 ++
>> drivers/iio/dac/Makefile | 1 +
>> drivers/iio/dac/ti-dac8554.c | 374 +++++++++++++++++++++++++++++++++++++++++++
>> 3 files changed, 385 insertions(+)
>> create mode 100644 drivers/iio/dac/ti-dac8554.c
>>
>> diff --git a/drivers/iio/dac/Kconfig b/drivers/iio/dac/Kconfig
>> index 2236ea2..1689260 100644
>> --- a/drivers/iio/dac/Kconfig
>> +++ b/drivers/iio/dac/Kconfig
>> @@ -181,4 +181,14 @@ config MCP4922
>> To compile this driver as a module, choose M here: the module
>> will be called mcp4922.
>>
>> +config TI_DAC8554
>> + tristate "TI DAC8554 driver"
>> + depends on SPI
>> + depends on OF
>> + help
>> + Say yes here to build the driver for the TI DAC8554.
>> +
>> + To compile this driver as a module, choose M here: the module
>> + will be called ti-dac8554.
>> +
>> endmenu
>> diff --git a/drivers/iio/dac/Makefile b/drivers/iio/dac/Makefile
>> index 52be7e1..b98d79a 100644
>> --- a/drivers/iio/dac/Makefile
>> +++ b/drivers/iio/dac/Makefile
>> @@ -20,3 +20,4 @@ obj-$(CONFIG_MAX517) += max517.o
>> obj-$(CONFIG_MAX5821) += max5821.o
>> obj-$(CONFIG_MCP4725) += mcp4725.o
>> obj-$(CONFIG_MCP4922) += mcp4922.o
>> +obj-$(CONFIG_TI_DAC8554) += ti-dac8554.o
>> diff --git a/drivers/iio/dac/ti-dac8554.c b/drivers/iio/dac/ti-dac8554.c
>> new file mode 100644
>> index 0000000..fca751f
>> --- /dev/null
>> +++ b/drivers/iio/dac/ti-dac8554.c
>> @@ -0,0 +1,374 @@
>> +/*
>> + * TI DAC8554 Digital to Analog Converter SPI driver
>> + *
>> + * Copyright (C) 2014 Avionic Design GmbH
>> + *
>> + * Based on ad5446r_spi.c
>> + * Copyright (C) 2010,2011 Analog Devices Inc.
>> + *
>> + * This program is free software; you can redistribute it and/or modify
>> + * it under the terms of the GNU General Public License version 2 as
>> + * published by the Free Software Foundation.
>> + */
>> +
>> +#include <linux/spi/spi.h>
>> +#include <linux/regulator/consumer.h>
>> +#include <linux/module.h>
>> +#include <linux/iio/iio.h>
>> +#include <linux/of.h>
>> +
>> +#define DAC8554_DRIVERNAME "ti-dac8554"
>> +#define DAC8554_DAC_CHANNELS 4
>> +
>> +/* Load commands */
>> +#define DAC8554_CMD_STORE_DAC_N 0x0
>> +#define DAC8554_CMD_UPDATE_DAC_N 0x1
>> +#define DAC8554_CMD_STORE_DAC_N_UPDATE_ALL 0x2
>> +#define DAC8554_CMD_UPDATE_BROADCAST 0x3
>> +
>> +#define DAC8554_BROADCAST_USE_SRDATA 0x2
> Add a blank line here.
>> +/* Powerdown modes (ORed PD1|PD2 bits) */
> It took my some time to figure out ORed. I think you could drop it and just
> mention (PD1 | PD2 bits).
>> +#define DAC8554_PWRDN_HIZ 0x0
>> +#define DAC8554_PWRDN_1K 0x1
>> +#define DAC8554_PWRDN_100K 0x2
>> +
>> +#define DAC8554_PWRDN_TO_SR(mode) (BIT(16) | (mode) << 14)
>> +
>> +/**
>> + * struct dac8554_state - driver instance specific data
>> + * @spi: spi_device
> SPI device?
>> + * @reg: supply regulator
>> + * @addr: two-bit chip address
>> + * @vref_mv: reference voltage in millivolt
>> + * @val DAC/channel data
> DAC channel data?
>> + * @powerdown channel powerdown flag
>> + * @powerdown_mode channel powerdown mode
>> + * @xfer SPI transfer buffer
> Half of the comments are with colon, the other half are missing it.
>> + */
>> +struct dac8554_state {
>> + struct spi_device *spi;
>> + struct regulator *reg;
>> + unsigned addr;
>> + unsigned vref_mv;
>> + u16 val[DAC8554_DAC_CHANNELS];
>> + bool powerdown[DAC8554_DAC_CHANNELS];
>> + u8 powerdown_mode[DAC8554_DAC_CHANNELS];
>> +
>> + /*
>> + * DMA (thus cache coherency maintenance) requires the
>> + * transfer buffers to live in their own cache lines.
>> + */
>> + u8 xfer[3] ____cacheline_aligned;
>> +};
>> +
>> +static int dac8554_spi_write(struct dac8554_state *st,
>> + unsigned cmd,
>> + unsigned chan_addr,
>> + unsigned val)
>> +{
>> + u32 data;
>> +
>> + /*
>> + * The input shift register is 24 bits wide. The 8 MSB are
>> + * control bits, followed by 16 data bits.
>> + * The first two bits A1 and A0 address a DAC8554 chip.
>> + * The next two are the command bits, LD1 and LD0.
>> + * After a don't-care-bit, the next two bits select the channel.
>> + * The final control bit PD0 is a flag signalling if the data
>> + * bits encode a powerdown mode. We merge PD0 with the adjacent
>> + * data bits.
>> + */
>> +
>> + if (cmd > 3 || chan_addr > 3 ||
>> + (val > 0xffff && (val & ~DAC8554_PWRDN_TO_SR(3))))
>> + return -EINVAL;
>> +
>> + data = (st->addr << 22) | (cmd << 20) | (chan_addr << 17) | val;
> Could be more readable by using definition for the magic shifts, or macros.
>> + st->xfer[0] = data >> 16;
>> + st->xfer[1] = data >> 8;
>> + st->xfer[2] = data;
>> +
>> + return spi_write(st->spi, st->xfer, sizeof(st->xfer));
>> +}
>> +
>> +static int dac8554_read_raw(struct iio_dev *indio_dev,
>> + struct iio_chan_spec const *chan,
>> + int *val,
>> + int *val2,
>> + long m)
> Commonly, m is called mask (like you do in _write_raw).
>> +{
>> + struct dac8554_state *st = iio_priv(indio_dev);
>> +
>> + switch (m) {
>> + case IIO_CHAN_INFO_RAW:
>> + *val = st->val[chan->address];
>> + return IIO_VAL_INT;
>> + case IIO_CHAN_INFO_SCALE:
>> + *val = st->vref_mv;
>> + *val2 = 16;
>> + return IIO_VAL_FRACTIONAL_LOG2;
>> + }
>> + return -EINVAL;
>> +}
>> +
>> +static int dac8554_write_raw(struct iio_dev *indio_dev,
>> + struct iio_chan_spec const *chan,
>> + int val,
>> + int val2,
>> + long mask)
>> +{
>> + struct dac8554_state *st = iio_priv(indio_dev);
>> + int err;
>> +
>> + switch (mask) {
>> + case IIO_CHAN_INFO_RAW:
>> + if (val > 0xffff || val < 0)
>> + return -EINVAL;
>> +
>> + err = dac8554_spi_write(st, DAC8554_CMD_UPDATE_DAC_N,
>> + chan->address, val);
>> + if (err)
>> + return err;
>> +
>> + st->val[chan->address] = val;
>> +
>> + /* By hw design, DAC updates automatically trigger powerup. */
>> + st->powerdown[chan->address] = false;
>> +
>> + return 0;
>> +
>> + default:
>> + return -EINVAL;
>> + }
>> +}
>> +
>> +static int dac8554_get_powerdown_mode(struct iio_dev *indio_dev,
>> + const struct iio_chan_spec *chan)
>> +{
>> + struct dac8554_state *st = iio_priv(indio_dev);
>> +
>> + return st->powerdown_mode[chan->address];
>> +}
>> +
>> +static int dac8554_set_powerdown_mode(struct iio_dev *indio_dev,
>> + const struct iio_chan_spec *chan,
>> + unsigned int mode)
>> +{
>> + struct dac8554_state *st = iio_priv(indio_dev);
>> +
>> + st->powerdown_mode[chan->address] = mode;
>> +
>> + return 0;
>> +}
>> +
>> +static ssize_t dac8554_read_dac_powerdown(struct iio_dev *indio_dev,
>> + uintptr_t private,
>> + const struct iio_chan_spec *chan,
>> + char *buf)
>> +{
>> + struct dac8554_state *st = iio_priv(indio_dev);
>> +
>> + return sprintf(buf, "%d\n", st->powerdown[chan->address]);
>> +}
>> +
>> +static ssize_t dac8554_write_dac_powerdown(struct iio_dev *indio_dev,
>> + uintptr_t private,
>> + const struct iio_chan_spec *chan,
>> + const char *buf,
>> + size_t len)
>> +{
>> + bool powerdown;
>> + int ret;
>> + struct dac8554_state *st = iio_priv(indio_dev);
>> + u8 powerdown_mode;
>> +
>> + ret = strtobool(buf, &powerdown);
>> + if (ret)
>> + return ret;
>> +
>> + st->powerdown[chan->address] = powerdown;
>> +
>> + if (powerdown) {
>> + powerdown_mode = st->powerdown_mode[chan->address];
>> + ret = dac8554_spi_write(st,
>> + DAC8554_CMD_UPDATE_DAC_N,
>> + chan->address,
>> + DAC8554_PWRDN_TO_SR(powerdown_mode));
> The parameters sill fit on line even with proper indentation.
>> + } else {
>> + /* Load DAC with cached value. This triggers a powerup. */
>> + ret = dac8554_spi_write(st,
>> + DAC8554_CMD_UPDATE_DAC_N,
>> + chan->address,
>> + st->val[chan->address]);
> Same here with indentation.
>> + }
>> +
>> + if (ret)
>> + return ret;
>> +
>> + return len;
> Just: return (ret) ? ret : len;
>> +}
>> +
>> +static int dac8554_powerdown(struct dac8554_state *st,
>> + u8 powerdown_mode)
>> +{
>> + int chan, cmd, ret;
>> +
>> + for (chan = DAC8554_DAC_CHANNELS-1; chan >= 0; --chan) {
> Please mind spaces around operators.
>> + cmd = chan ? DAC8554_CMD_STORE_DAC_N
>> + : DAC8554_CMD_STORE_DAC_N_UPDATE_ALL;
>> + ret = dac8554_spi_write(st, cmd, chan,
>> + DAC8554_PWRDN_TO_SR(powerdown_mode));
>> + if (ret)
>> + return ret;
>> + }
>> +
>> + memset(st->powerdown_mode, powerdown_mode, sizeof(st->powerdown_mode));
>> + memset(st->powerdown, true, sizeof(st->powerdown));
Whilst this probably works, I think for the boolean case it is less
than entirely obvious, so probably better to have a simple loop.
>> +
>> + return 0;
>> +}
>> +
>> +static const struct iio_info dac8554_info = {
>> + .write_raw = dac8554_write_raw,
>> + .read_raw = dac8554_read_raw,
>> + .driver_module = THIS_MODULE,
>> +};
>> +
>> +static const char * const dac8554_powerdown_modes[] = {
>> + "three_state",
>> + "1kohm_to_gnd",
>> + "100kohm_to_gnd"
>> +};
>> +
>> +static const struct iio_enum dac8854_powerdown_mode_enum = {
>> + .items = dac8554_powerdown_modes,
>> + .num_items = ARRAY_SIZE(dac8554_powerdown_modes),
>> + .get = dac8554_get_powerdown_mode,
>> + .set = dac8554_set_powerdown_mode,
>> +};
>> +
>> +static const struct iio_chan_spec_ext_info dac8554_ext_info[] = {
>> + {
>> + .name = "powerdown",
>> + .read = dac8554_read_dac_powerdown,
>> + .write = dac8554_write_dac_powerdown,
>> + .shared = IIO_SEPARATE,
>> + },
>> + IIO_ENUM("powerdown_mode", IIO_SEPARATE,
>> + &dac8854_powerdown_mode_enum),
>> + IIO_ENUM_AVAILABLE("powerdown_mode", &dac8854_powerdown_mode_enum),
>> + { },
>> +};
>> +
>> +#define DAC8554_CHANNEL(chan) { \
>> + .type = IIO_VOLTAGE, \
>> + .indexed = 1, \
>> + .output = 1, \
>> + .channel = (chan), \
>> + .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
>> + .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \
>> + .address = (chan), \
>> + .ext_info = dac8554_ext_info, \
>> +}
>> +const struct iio_chan_spec dac8554_channels[] = {
>> + DAC8554_CHANNEL(0),
>> + DAC8554_CHANNEL(1),
>> + DAC8554_CHANNEL(2),
>> + DAC8554_CHANNEL(3),
>> +};
>> +#undef DAC8554_CHANNEL
>> +
>> +static int dac8554_probe(struct spi_device *spi)
>> +{
>> + struct dac8554_state *st;
>> + struct iio_dev *indio_dev;
>> + int ret, voltage_uv;
>> + u32 addr;
>> +
>> + indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*st));
>> + if (!indio_dev)
>> + return -ENOMEM;
>> +
>> + indio_dev->dev.parent = &spi->dev;
>> + indio_dev->name = DAC8554_DRIVERNAME;
>> + indio_dev->info = &dac8554_info;
>> + indio_dev->modes = INDIO_DIRECT_MODE;
>> + indio_dev->channels = dac8554_channels;
>> + indio_dev->num_channels = ARRAY_SIZE(dac8554_channels);
>> +
>> + spi_set_drvdata(spi, indio_dev);
>> +
>> + st = iio_priv(indio_dev);
>> +
>> + if (!spi->dev.of_node) {
>> + dev_err(&spi->dev, "missing OF node");
>> + return -ENODEV;
>> + }
>> + ret = of_property_read_u32(spi->dev.of_node, "address", &addr);
>> + if (ret || addr < 0 || addr > 2) {
>> + dev_err(&spi->dev, "no or invalid chip address");
>> + return -ENODEV;
>> + }
>> +
>> + st->spi = spi;
>> + st->addr = addr;
>> +
> According to your DT bindings, the regulator from property "vref-supply" should
> be used. This is missing here.
>> + st->reg = devm_regulator_get(&spi->dev, "vref");
>> + if (IS_ERR(st->reg))
>> + return PTR_ERR(st->reg);
>> +
>> + ret = regulator_enable(st->reg);
>> + if (ret)
>> + return ret;
>> +
>> + voltage_uv = regulator_get_voltage(st->reg);
>> + if (voltage_uv < 0)
>> + goto error_disable_reg;
> Missing ret = voltage_uv before goto. Or just drop voltage_uv completely and use ret instead.
>> + st->vref_mv = voltage_uv / 1000;
> How hard do you want to depend on a voltage regulator? Doing regulator_get_voltage()
> could even be called dynamically in _read_raw(), making a real regulator optional.
>> +
>> + ret = dac8554_powerdown(st, DAC8554_PWRDN_100K);
>> + if (ret)
>> + goto error_disable_reg;
>> +
>> + ret = iio_device_register(indio_dev);
>> + if (ret)
>> + goto error_disable_reg;
>> +
>> + return 0;
>> +
>> +error_disable_reg:
>> + regulator_disable(st->reg);
>> + return ret;
>> +}
>> +
>> +static int dac8554_remove(struct spi_device *spi)
>> +{
>> + struct iio_dev *indio_dev = spi_get_drvdata(spi);
>> + struct dac8554_state *st = iio_priv(indio_dev);
>> +
>> + iio_device_unregister(indio_dev);
>> + regulator_disable(st->reg);
>> +
>> + return 0;
>> +}
>> +
>> +static const struct of_device_id dac8554_of_match[] = {
>> + { .compatible = "ti,dac8554" },
>> + { }
>> +};
>> +MODULE_DEVICE_TABLE(of, dac8554_of_match);
>> +
>> +static struct spi_driver dac8554_driver = {
>> + .driver = {
>> + .name = DAC8554_DRIVERNAME,
>> + .owner = THIS_MODULE,
>> + .of_match_table = dac8554_of_match,
>> + },
>> + .probe = dac8554_probe,
>> + .remove = dac8554_remove,
>> +};
>> +module_spi_driver(dac8554_driver);
>> +
>> +MODULE_AUTHOR("Nikolaus Schulz <nikolaus.schulz@xxxxxxxxxxxxxxxxx>");
>> +MODULE_DESCRIPTION("Texas Instruments DAC8554 SPI driver");
>> +MODULE_LICENSE("GPL v2");
>>
>
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