From patchwork Thu Jan 12 22:51:39 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jacopo Mondi X-Patchwork-Id: 9514399 X-Patchwork-Delegate: geert@linux-m68k.org Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id CD06F60710 for ; Thu, 12 Jan 2017 22:51:53 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id CEFC128723 for ; Thu, 12 Jan 2017 22:51:53 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id C366928727; Thu, 12 Jan 2017 22:51:53 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.9 required=2.0 tests=BAYES_00,RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id AEA3D28723 for ; Thu, 12 Jan 2017 22:51:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1750908AbdALWvv (ORCPT ); Thu, 12 Jan 2017 17:51:51 -0500 Received: from relay3-d.mail.gandi.net ([217.70.183.195]:58213 "EHLO relay3-d.mail.gandi.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750860AbdALWvu (ORCPT ); Thu, 12 Jan 2017 17:51:50 -0500 Received: from w540.lan (unknown [IPv6:2001:b07:6442:1ac4:7429:e26d:88ff:936]) (Authenticated sender: jacopo@jmondi.org) by relay3-d.mail.gandi.net (Postfix) with ESMTPSA id 08928A80CE; Thu, 12 Jan 2017 23:51:44 +0100 (CET) From: Jacopo Mondi To: wsa+renesas@sang-engineering.com, magnus.damm@gmail.com, jic23@kernel.org, knaack.h@gmx.de, lars@metafoo.de, pmeerw@pmeerw.net, marek.vasut@gmail.com, geert@linux-m68k.org Cc: linux-iio@vger.kernel.org, linux-renesas-soc@vger.kernel.org Subject: [PATCH v3] iio: adc: Add Maxim MAX11100 driver Date: Thu, 12 Jan 2017 23:51:39 +0100 Message-Id: <1484261499-7729-1-git-send-email-jacopo+renesas@jmondi.org> X-Mailer: git-send-email 2.7.4 Sender: linux-renesas-soc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-renesas-soc@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP From: Jacopo Mondi Add IIO driver for Maxim MAX11100 single-channel ADC. Add DT bindings documentation. Signed-off-by: Jacopo Mondi Tested-by: Marek Vasut --- Sending v3 incorporating last comments from review and from testing. One final thing I would like to be clarified is about the measure unit returned by read_raw(). Currently (value_raw * value_scale) return the ADC input value in mV. While testing the patch I've been questioned if that should not actually be in uV. This is easily achievable making _scale return a value in uV. I have found no mention of this in the ABI documentation as it speaks of generic voltage. Can we have a final word on this? Thanks Marek for having tested this. v1 -> v2: - incorporated pmeerw's review comments - retrieve vref from dts and use that to convert read_raw result to mV - add device tree bindings documentation v2 -> v3: - add _SCALE bit of read_raw function and change _RAW bit accordingly - call regulator_get_voltage when accessing the _SCALE part of read_raw and not during probe - add back remove function as regulator has to be disabled when detaching the module. Do not use devm_ version of iio_register/unregister functions anymore but do unregister in the remove. - remove mutex as access to SPI bus is protected by SPI core. Thanks marex --- .../devicetree/bindings/iio/adc/max11100.txt | 17 ++ drivers/iio/adc/Kconfig | 9 + drivers/iio/adc/Makefile | 1 + drivers/iio/adc/max11100.c | 187 +++++++++++++++++++++ 4 files changed, 214 insertions(+) create mode 100644 Documentation/devicetree/bindings/iio/adc/max11100.txt create mode 100644 drivers/iio/adc/max11100.c diff --git a/Documentation/devicetree/bindings/iio/adc/max11100.txt b/Documentation/devicetree/bindings/iio/adc/max11100.txt new file mode 100644 index 0000000..6877c11 --- /dev/null +++ b/Documentation/devicetree/bindings/iio/adc/max11100.txt @@ -0,0 +1,17 @@ +* Maxim max11100 Analog to Digital Converter (ADC) + +Required properties: + - compatible: Should be "maxim,max11100" + - vref-supply: phandle to the regulator that provides reference voltage + +Optional properties: + - spi-max-frequency: SPI maximum frequency + +Example: + +adc0: max11100@0 { + compatible = "maxim,max11100"; + vref-supply = <&adc0_vref>; + spi-max-frequency = <240000>; +}; + diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig index 38bc319..c32bc7a 100644 --- a/drivers/iio/adc/Kconfig +++ b/drivers/iio/adc/Kconfig @@ -307,6 +307,15 @@ config MAX1027 To compile this driver as a module, choose M here: the module will be called max1027. +config MAX11100 + tristate "Maxim max11100 ADC driver" + depends on SPI_MASTER + help + Say yes here to build support for Maxim max11100 SPI ADC + + To compile this driver as a module, choose M here: the module will be + called max11100. + config MAX1363 tristate "Maxim max1363 ADC driver" depends on I2C diff --git a/drivers/iio/adc/Makefile b/drivers/iio/adc/Makefile index d36c4be..5684369 100644 --- a/drivers/iio/adc/Makefile +++ b/drivers/iio/adc/Makefile @@ -31,6 +31,7 @@ obj-$(CONFIG_LP8788_ADC) += lp8788_adc.o obj-$(CONFIG_LPC18XX_ADC) += lpc18xx_adc.o obj-$(CONFIG_LTC2485) += ltc2485.o obj-$(CONFIG_MAX1027) += max1027.o +obj-$(CONFIG_MAX11100) += max11100.o obj-$(CONFIG_MAX1363) += max1363.o obj-$(CONFIG_MCP320X) += mcp320x.o obj-$(CONFIG_MCP3422) += mcp3422.o diff --git a/drivers/iio/adc/max11100.c b/drivers/iio/adc/max11100.c new file mode 100644 index 0000000..78e2a45 --- /dev/null +++ b/drivers/iio/adc/max11100.c @@ -0,0 +1,187 @@ +/* + * iio/adc/max11100.c + * Maxim max11100 ADC Driver with IIO interface + * + * Copyright (C) 2016 Renesas Electronics Corporation + * Copyright (C) 2016 Jacopo Mondi + * + * 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 + +#include +#include +#include + +/* + * LSB is the ADC single digital step + * 1 LSB = (vref_mv / 2 ^ 16) + * + * LSB is used to calculate analog voltage value + * from the number of ADC steps count + * + * Ain = (count * LSB) + */ +#define MAX11100_LSB_DIV (1 << 16) + +struct max11100_state { + const struct max11100_chip_desc *desc; + struct regulator *vref_reg; + struct spi_device *spi; +}; + +static struct iio_chan_spec max11100_channels[] = { + { /* [0] */ + .type = IIO_VOLTAGE, + .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | + BIT(IIO_CHAN_INFO_SCALE), + }, +}; + +static struct max11100_chip_desc { + unsigned int num_chan; + const struct iio_chan_spec *channels; +} max11100_desc = { + .num_chan = ARRAY_SIZE(max11100_channels), + .channels = max11100_channels, +}; + +static int max11100_read_single(struct iio_dev *indio_dev, int *val) +{ + int ret; + struct max11100_state *state = iio_priv(indio_dev); + uint8_t buffer[3]; + + ret = spi_read(state->spi, buffer, sizeof(buffer)); + if (ret) { + dev_err(&indio_dev->dev, "SPI transfer failed\n"); + return ret; + } + + /* the first 8 bits sent out from ADC must be 0s */ + if (buffer[0]) { + dev_err(&indio_dev->dev, "Invalid value: buffer[0] != 0\n"); + return -EINVAL; + } + + *val = (buffer[1] << 8) | buffer[2]; + + return 0; +} + +static int max11100_read_raw(struct iio_dev *indio_dev, + struct iio_chan_spec const *chan, + int *val, int *val2, long info) +{ + int ret, vref_uv; + struct max11100_state *state = iio_priv(indio_dev); + + switch (info) { + case IIO_CHAN_INFO_RAW: + ret = max11100_read_single(indio_dev, val); + if (ret) + return ret; + + return IIO_VAL_INT; + + case IIO_CHAN_INFO_SCALE: + vref_uv = regulator_get_voltage(state->vref_reg); + if (vref_uv < 0) + /* dummy regulator "get_voltage" returns -EINVAL */ + return -EINVAL; + + *val = vref_uv / 1000; + *val2 = MAX11100_LSB_DIV; + return IIO_VAL_FRACTIONAL; + } + + return -EINVAL; +} + +static const struct iio_info max11100_info = { + .driver_module = THIS_MODULE, + .read_raw = max11100_read_raw, +}; + +static int max11100_probe(struct spi_device *spi) +{ + int ret; + struct iio_dev *indio_dev; + struct max11100_state *state; + + indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*state)); + if (!indio_dev) + return -ENOMEM; + + spi_set_drvdata(spi, indio_dev); + + state = iio_priv(indio_dev); + state->spi = spi; + state->desc = &max11100_desc; + + indio_dev->dev.parent = &spi->dev; + indio_dev->dev.of_node = spi->dev.of_node; + indio_dev->info = &max11100_info; + indio_dev->modes = INDIO_DIRECT_MODE; + indio_dev->channels = state->desc->channels; + indio_dev->num_channels = state->desc->num_chan; + + state->vref_reg = devm_regulator_get(&spi->dev, "vref"); + if (IS_ERR(state->vref_reg)) + return PTR_ERR(state->vref_reg); + + ret = regulator_enable(state->vref_reg); + if (ret) + return ret; + + ret = iio_device_register(indio_dev); + if (ret) + goto disable_regulator; + + return 0; + +disable_regulator: + regulator_disable(state->vref_reg); + + return ret; +} + +static int max11100_remove(struct spi_device *spi) +{ + struct iio_dev *indio_dev = spi_get_drvdata(spi); + struct max11100_state *state = iio_priv(indio_dev); + + regulator_disable(state->vref_reg); + + iio_device_unregister(indio_dev); + + return 0; +} + +static const struct of_device_id max11100_ids[] = { + {.compatible = "maxim,max11100"}, + { }, +}; +MODULE_DEVICE_TABLE(of, max11100_ids); + +static struct spi_driver max11100_driver = { + .driver = { + .name = "max11100", + .owner = THIS_MODULE, + .of_match_table = of_match_ptr(max11100_ids), + }, + .probe = max11100_probe, + .remove = max11100_remove, +}; + +module_spi_driver(max11100_driver); + +MODULE_AUTHOR("Jacopo Mondi "); +MODULE_DESCRIPTION("Maxim max11100 ADC Driver"); +MODULE_LICENSE("GPL v2");