Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S967490AbaLLL5S (ORCPT ); Fri, 12 Dec 2014 06:57:18 -0500 Received: from saturn.retrosnub.co.uk ([178.18.118.26]:47444 "EHLO saturn.retrosnub.co.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S965873AbaLLL5Q (ORCPT ); Fri, 12 Dec 2014 06:57:16 -0500 Message-ID: <548AD814.2060206@kernel.org> Date: Fri, 12 Dec 2014 11:57:08 +0000 From: Jonathan Cameron User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.2.0 MIME-Version: 1.0 To: Hartmut Knaack , Nikolaus Schulz , Lars-Peter Clausen , Peter Meerwald , Grant Likely , Rob Herring , Michael Welling , Philippe Reynes , linux-kernel@vger.kernel.org, linux-iio@vger.kernel.org, devicetree@vger.kernel.org CC: Alban Bedel Subject: Re: [PATCH v2 2/2] iio: add driver for the TI DAC8554 References: <1416858614-32265-1-git-send-email-nikolaus.schulz@avionic-design.de> <1416858614-32265-2-git-send-email-nikolaus.schulz@avionic-design.de> <5482EA33.7020305@gmx.de> In-Reply-To: <5482EA33.7020305@gmx.de> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 >> --- >> 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 >> +#include >> +#include >> +#include >> +#include >> + >> +#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 "); >> +MODULE_DESCRIPTION("Texas Instruments DAC8554 SPI driver"); >> +MODULE_LICENSE("GPL v2"); >> > > -- > To unsubscribe from this list: send the line "unsubscribe linux-iio" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/