[PATCH v2 3/6] iio: adc: Add support for STM32 ADC
Jonathan Cameron
jic23 at kernel.org
Sat Nov 12 09:08:50 PST 2016
On 10/11/16 16:18, Fabrice Gasnier wrote:
> This patch adds support for STMicroelectronics STM32 MCU's analog to
> digital converter.
>
> Signed-off-by: Fabrice Gasnier <fabrice.gasnier at st.com>
Nice and clean - few minor things inline.
Jonathan
> ---
> drivers/iio/adc/Kconfig | 10 +
> drivers/iio/adc/Makefile | 1 +
> drivers/iio/adc/stm32-adc.c | 525 ++++++++++++++++++++++++++++++++++++++++++++
> 3 files changed, 536 insertions(+)
> create mode 100644 drivers/iio/adc/stm32-adc.c
>
> diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
> index 7edcf32..61ba674 100644
> --- a/drivers/iio/adc/Kconfig
> +++ b/drivers/iio/adc/Kconfig
> @@ -419,6 +419,16 @@ config ROCKCHIP_SARADC
> To compile this driver as a module, choose M here: the
> module will be called rockchip_saradc.
>
> +config STM32_ADC
> + tristate "STMicroelectronics STM32 adc"
> + depends on MFD_STM32_ADC
> + help
> + Say yes here to build support for STMicroelectronics stm32 Analog
> + to Digital Converter (ADC).
> +
> + This driver can also be built as a module. If so, the module
> + will be called stm32-adc.
> +
> config STX104
> tristate "Apex Embedded Systems STX104 driver"
> depends on X86 && ISA_BUS_API
> diff --git a/drivers/iio/adc/Makefile b/drivers/iio/adc/Makefile
> index 7a40c04..df7a221 100644
> --- a/drivers/iio/adc/Makefile
> +++ b/drivers/iio/adc/Makefile
> @@ -41,6 +41,7 @@ obj-$(CONFIG_QCOM_SPMI_IADC) += qcom-spmi-iadc.o
> obj-$(CONFIG_QCOM_SPMI_VADC) += qcom-spmi-vadc.o
> obj-$(CONFIG_ROCKCHIP_SARADC) += rockchip_saradc.o
> obj-$(CONFIG_STX104) += stx104.o
> +obj-$(CONFIG_STM32_ADC) += stm32-adc.o
> obj-$(CONFIG_TI_ADC081C) += ti-adc081c.o
> obj-$(CONFIG_TI_ADC0832) += ti-adc0832.o
> obj-$(CONFIG_TI_ADC12138) += ti-adc12138.o
> diff --git a/drivers/iio/adc/stm32-adc.c b/drivers/iio/adc/stm32-adc.c
> new file mode 100644
> index 0000000..2be5fee
> --- /dev/null
> +++ b/drivers/iio/adc/stm32-adc.c
> @@ -0,0 +1,525 @@
> +/*
> + * This file is part of STM32 ADC driver
> + *
> + * Copyright (C) 2016, STMicroelectronics - All Rights Reserved
> + * Author: Fabrice Gasnier <fabrice.gasnier at st.com>.
> + *
> + * License type: GPLv2
> + *
> + * 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.
> + *
> + * This program is distributed in the hope that it will be useful, but
> + * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
> + * or FITNESS FOR A PARTICULAR PURPOSE.
> + * See the GNU General Public License for more details.
> + *
> + * You should have received a copy of the GNU General Public License along with
> + * this program. If not, see <http://www.gnu.org/licenses/>.
> + */
> +
> +#include <linux/clk.h>
> +#include <linux/delay.h>
> +#include <linux/iio/iio.h>
> +#include <linux/interrupt.h>
> +#include <linux/io.h>
> +#include <linux/mfd/stm32-adc-core.h>
> +#include <linux/module.h>
> +#include <linux/platform_device.h>
> +#include <linux/of.h>
> +
> +/* STM32F4 - Registers for each ADC instance */
Not really sure the X adds anything in these, but doesn't do much harm
I guess ;)
> +#define STM32F4_ADCX_SR 0x00
> +#define STM32F4_ADCX_CR1 0x04
> +#define STM32F4_ADCX_CR2 0x08
> +#define STM32F4_ADCX_SMPR1 0x0C
> +#define STM32F4_ADCX_SMPR2 0x10
> +#define STM32F4_ADCX_HTR 0x24
> +#define STM32F4_ADCX_LTR 0x28
> +#define STM32F4_ADCX_SQR1 0x2C
> +#define STM32F4_ADCX_SQR2 0x30
> +#define STM32F4_ADCX_SQR3 0x34
> +#define STM32F4_ADCX_JSQR 0x38
> +#define STM32F4_ADCX_JDR1 0x3C
> +#define STM32F4_ADCX_JDR2 0x40
> +#define STM32F4_ADCX_JDR3 0x44
> +#define STM32F4_ADCX_JDR4 0x48
> +#define STM32F4_ADCX_DR 0x4C
> +
> +/* STM32F4_ADCX_SR - bit fields */
> +#define STM32F4_OVR BIT(5)
> +#define STM32F4_STRT BIT(4)
> +#define STM32F4_EOC BIT(1)
> +
> +/* STM32F4_ADCX_CR1 - bit fields */
> +#define STM32F4_OVRIE BIT(26)
> +#define STM32F4_SCAN BIT(8)
> +#define STM32F4_EOCIE BIT(5)
> +
> +/* STM32F4_ADCX_CR2 - bit fields */
> +#define STM32F4_SWSTART BIT(30)
> +#define STM32F4_EXTEN_MASK GENMASK(29, 28)
> +#define STM32F4_EOCS BIT(10)
> +#define STM32F4_ADON BIT(0)
> +
> +/* STM32F4_ADCX_SQR1 - bit fields */
> +#define STM32F4_L_SHIFT 20
> +#define STM32F4_L_MASK GENMASK(23, 20)
> +
> +/* STM32F4_ADCX_SQR3 - bit fields */
> +#define STM32F4_SQ1_SHIFT 0
> +#define STM32F4_SQ1_MASK GENMASK(4, 0)
> +
> +#define STM32_ADC_MAX_SQ 16 /* SQ1..SQ16 */
> +#define STM32_ADC_TIMEOUT_US 100000
> +#define STM32_ADC_TIMEOUT (msecs_to_jiffies(STM32_ADC_TIMEOUT_US / 1000))
> +
> +/**
> + * struct stm32_adc - private data of each ADC IIO instance
> + * @common: reference to ADC block common data
> + * @offset: ADC instance register offset in ADC block
> + * @completion: end of single conversion completion
> + * @buffer: data buffer
> + * @clk: optional adc clock, for this adc instance
> + * @irq: interrupt for this adc instance
> + * @lock: spinlock
> + */
> +struct stm32_adc {
> + struct stm32_adc_common *common;
> + u32 offset;
> + struct completion completion;
> + u16 *buffer;
> + struct clk *clk;
> + int irq;
> + spinlock_t lock; /* interrupt lock */
> +};
> +
> +/**
> + * struct stm32_adc_chan_spec - specification of stm32 adc channel
> + * @type: IIO channel type
> + * @channel: channel number (single ended)
> + * @name: channel name (single ended)
> + */
> +struct stm32_adc_chan_spec {
> + enum iio_chan_type type;
> + int channel;
> + const char *name;
> +};
> +
> +/* Input definitions common for all STM32F4 instances */
> +static const struct stm32_adc_chan_spec stm32f4_adc123_channels[] = {
> + { IIO_VOLTAGE, 0, "in0" },
> + { IIO_VOLTAGE, 1, "in1" },
> + { IIO_VOLTAGE, 2, "in2" },
> + { IIO_VOLTAGE, 3, "in3" },
> + { IIO_VOLTAGE, 4, "in4" },
> + { IIO_VOLTAGE, 5, "in5" },
> + { IIO_VOLTAGE, 6, "in6" },
> + { IIO_VOLTAGE, 7, "in7" },
> + { IIO_VOLTAGE, 8, "in8" },
> + { IIO_VOLTAGE, 9, "in9" },
> + { IIO_VOLTAGE, 10, "in10" },
> + { IIO_VOLTAGE, 11, "in11" },
> + { IIO_VOLTAGE, 12, "in12" },
> + { IIO_VOLTAGE, 13, "in13" },
> + { IIO_VOLTAGE, 14, "in14" },
> + { IIO_VOLTAGE, 15, "in15" },
> +};
> +
> +/**
> + * STM32 ADC registers access routines
> + * @adc: stm32 adc instance
> + * @reg: reg offset in adc instance
> + *
> + * Note: All instances share same base, with 0x0, 0x100 or 0x200 offset resp.
> + * for adc1, adc2 and adc3.
> + */
> +static u32 stm32_adc_readl(struct stm32_adc *adc, u32 reg)
> +{
> + return readl_relaxed(adc->common->base + adc->offset + reg);
> +}
> +
> +static u32 stm32_adc_readw(struct stm32_adc *adc, u32 reg)
> +{
> + return readw_relaxed(adc->common->base + adc->offset + reg);
> +}
> +
> +static void stm32_adc_writel(struct stm32_adc *adc, u32 reg, u32 val)
> +{
> + writel_relaxed(val, adc->common->base + adc->offset + reg);
> +}
> +
> +static void stm32_adc_set_bits(struct stm32_adc *adc, u32 reg, u32 bits)
> +{
> + unsigned long flags;
> +
> + spin_lock_irqsave(&adc->lock, flags);
> + stm32_adc_writel(adc, reg, stm32_adc_readl(adc, reg) | bits);
> + spin_unlock_irqrestore(&adc->lock, flags);
> +}
> +
> +static void stm32_adc_clr_bits(struct stm32_adc *adc, u32 reg, u32 bits)
> +{
> + unsigned long flags;
> +
> + spin_lock_irqsave(&adc->lock, flags);
> + stm32_adc_writel(adc, reg, stm32_adc_readl(adc, reg) & ~bits);
> + spin_unlock_irqrestore(&adc->lock, flags);
> +}
> +
> +/**
> + * stm32_adc_conv_irq_enable() - Enable end of conversion interrupt
> + * @adc: stm32 adc instance
> + */
> +static void stm32_adc_conv_irq_enable(struct stm32_adc *adc)
> +{
> + stm32_adc_set_bits(adc, STM32F4_ADCX_CR1, STM32F4_EOCIE);
> +};
> +
> +/**
> + * stm32_adc_conv_irq_disable() - Disable end of conversion interrupt
> + * @adc: stm32 adc instance
> + */
> +static void stm32_adc_conv_irq_disable(struct stm32_adc *adc)
> +{
> + stm32_adc_clr_bits(adc, STM32F4_ADCX_CR1, STM32F4_EOCIE);
> +}
> +
> +/**
> + * stm32_adc_start_conv() - Start conversions for regular channels.
> + * @adc: stm32 adc instance
> + */
> +static void stm32_adc_start_conv(struct stm32_adc *adc)
> +{
> + stm32_adc_set_bits(adc, STM32F4_ADCX_CR1, STM32F4_SCAN);
> + stm32_adc_set_bits(adc, STM32F4_ADCX_CR2, STM32F4_EOCS | STM32F4_ADON);
> +
> + /* Wait for Power-up time (tSTAB from datasheet) */
> + usleep_range(2, 3);
> +
> + /* Software start ? (e.g. trigger detection disabled ?) */
> + if (!(stm32_adc_readl(adc, STM32F4_ADCX_CR2) & STM32F4_EXTEN_MASK))
> + stm32_adc_set_bits(adc, STM32F4_ADCX_CR2, STM32F4_SWSTART);
> +}
> +
> +static void stm32_adc_stop_conv(struct stm32_adc *adc)
> +{
> + stm32_adc_clr_bits(adc, STM32F4_ADCX_CR2, STM32F4_EXTEN_MASK);
> + stm32_adc_clr_bits(adc, STM32F4_ADCX_SR, STM32F4_STRT);
> +
> + stm32_adc_clr_bits(adc, STM32F4_ADCX_CR1, STM32F4_SCAN);
> + stm32_adc_clr_bits(adc, STM32F4_ADCX_CR2, STM32F4_ADON);
> +}
> +
> +/**
> + * stm32_adc_single_conv() - Performs a single conversion
> + * @indio_dev: IIO device
> + * @chan: IIO channel
> + * @res: conversion result
> + *
> + * The function performs a single conversion on a given channel:
> + * - Program sequencer with one channel (e.g. in SQ1 with len = 1)
> + * - Use SW trigger
> + * - Start conversion, then wait for interrupt completion.
> + */
> +static int stm32_adc_single_conv(struct iio_dev *indio_dev,
> + const struct iio_chan_spec *chan,
> + int *res)
> +{
> + struct stm32_adc *adc = iio_priv(indio_dev);
> + long timeout;
> + u32 val;
> + u16 result;
> + int ret;
> +
> + reinit_completion(&adc->completion);
> +
> + adc->buffer = &result;
> +
> + /* Program chan number in regular sequence */
> + val = stm32_adc_readl(adc, STM32F4_ADCX_SQR3);
> + val &= ~STM32F4_SQ1_MASK;
> + val |= chan->channel << STM32F4_SQ1_SHIFT;
> + stm32_adc_writel(adc, STM32F4_ADCX_SQR3, val);
> +
> + /* Set regular sequence len (0 for 1 conversion) */
> + stm32_adc_clr_bits(adc, STM32F4_ADCX_SQR1, STM32F4_L_MASK);
> +
> + /* Trigger detection disabled (conversion can be launched in SW) */
> + stm32_adc_clr_bits(adc, STM32F4_ADCX_CR2, STM32F4_EXTEN_MASK);
> +
> + stm32_adc_conv_irq_enable(adc);
> +
> + stm32_adc_start_conv(adc);
> +
> + timeout = wait_for_completion_interruptible_timeout(
> + &adc->completion, STM32_ADC_TIMEOUT);
> + if (timeout == 0) {
> + dev_warn(&indio_dev->dev, "Conversion timed out!\n");
> + ret = -ETIMEDOUT;
> + } else if (timeout < 0) {
> + dev_warn(&indio_dev->dev, "Interrupted conversion!\n");
> + ret = -EINTR;
> + } else {
> + *res = result;
> + ret = IIO_VAL_INT;
> + }
> +
> + stm32_adc_stop_conv(adc);
> +
> + stm32_adc_conv_irq_disable(adc);
> +
> + return ret;
> +}
> +
> +static int stm32_adc_read_raw(struct iio_dev *indio_dev,
> + struct iio_chan_spec const *chan,
> + int *val, int *val2, long mask)
> +{
> + struct stm32_adc *adc = iio_priv(indio_dev);
> + int ret = -EINVAL;
> +
> + switch (mask) {
> + case IIO_CHAN_INFO_RAW:
> + ret = iio_device_claim_direct_mode(indio_dev);
> + if (ret)
> + return ret;
> + if (chan->type == IIO_VOLTAGE)
> + ret = stm32_adc_single_conv(indio_dev, chan, val);
> + else
> + ret = -EINVAL;
> + iio_device_release_direct_mode(indio_dev);
return directly here. Basically always preferred to return directly if
there is not cleanup to be done.
> + break;
> + case IIO_CHAN_INFO_SCALE:
> + *val = adc->common->vref_mv;
> + *val2 = chan->scan_type.realbits;
> + ret = IIO_VAL_FRACTIONAL_LOG2;
return directly here.
> + break;
> + default:
return -EINVAL here.
> + break;
> + }
> +
> + return ret;
> +}
> +
> +static irqreturn_t stm32_adc_isr(int irq, void *data)
> +{
> + struct stm32_adc *adc = data;
> + u32 status = stm32_adc_readl(adc, STM32F4_ADCX_SR);
> + irqreturn_t ret = IRQ_NONE;
> +
> + if (status & STM32F4_EOC) {
> + *adc->buffer = stm32_adc_readw(adc, STM32F4_ADCX_DR);
> + complete(&adc->completion);
> + ret = IRQ_HANDLED;
Slightly tidier to return IRQ_HANDLED here and directly return
IRQ_NONE below.
> + }
> +
> + return ret;
> +}
> +
> +static int stm32_adc_of_xlate(struct iio_dev *indio_dev,
> + const struct of_phandle_args *iiospec)
> +{
> + int i;
> +
> + for (i = 0; i < indio_dev->num_channels; i++)
> + if (indio_dev->channels[i].channel == iiospec->args[0])
> + return i;
> +
> + return -EINVAL;
> +}
> +
> +/**
> + * stm32_adc_debugfs_reg_access - read or write register value
> + *
> + * To read a value from an ADC register:
> + * echo [ADC reg offset] > direct_reg_access
> + * cat direct_reg_access
> + *
> + * To write a value in a ADC register:
> + * echo [ADC_reg_offset] [value] > direct_reg_access
> + */
> +static int stm32_adc_debugfs_reg_access(struct iio_dev *indio_dev,
> + unsigned reg, unsigned writeval,
> + unsigned *readval)
> +{
> + struct stm32_adc *adc = iio_priv(indio_dev);
> +
> + if (!readval)
> + stm32_adc_writel(adc, reg, writeval);
> + else
> + *readval = stm32_adc_readl(adc, reg);
> +
> + return 0;
> +}
> +
> +static const struct iio_info stm32_adc_iio_info = {
> + .read_raw = stm32_adc_read_raw,
> + .debugfs_reg_access = stm32_adc_debugfs_reg_access,
> + .of_xlate = stm32_adc_of_xlate,
> + .driver_module = THIS_MODULE,
> +};
> +
> +static void stm32_adc_chan_init_one(struct iio_dev *indio_dev,
> + struct iio_chan_spec *chan,
> + const struct stm32_adc_chan_spec *channel,
> + int scan_index)
> +{
> + chan->type = channel->type;
> + chan->channel = channel->channel;
> + chan->datasheet_name = channel->name;
> + chan->extend_name = channel->name;
Don't set extend_name. That name doesn't add sufficient information to
make it worth adding custom ABI to the userspace interface.
> + chan->scan_index = scan_index;
> + chan->indexed = 1;
> + chan->info_mask_separate = BIT(IIO_CHAN_INFO_RAW);
> + chan->info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE);
> + chan->scan_type.sign = 'u';
> + chan->scan_type.realbits = 12;
> + chan->scan_type.storagebits = 16;
> +}
> +
> +static int stm32_adc_chan_of_init(struct iio_dev *indio_dev)
> +{
> + struct device_node *node = indio_dev->dev.of_node;
> + struct property *prop;
> + const __be32 *cur;
> + struct iio_chan_spec *channels;
> + int scan_index = 0, num_channels;
> + u32 val;
> +
> + num_channels = of_property_count_u32_elems(node, "st,adc-channels");
> + if (num_channels < 0 ||
> + num_channels >= ARRAY_SIZE(stm32f4_adc123_channels)) {
> + dev_err(&indio_dev->dev, "Bad st,adc-channels?\n");
> + return num_channels < 0 ? num_channels : -EINVAL;
> + }
> +
> + channels = devm_kcalloc(&indio_dev->dev, num_channels,
> + sizeof(struct iio_chan_spec), GFP_KERNEL);
> + if (!channels)
> + return -ENOMEM;
> +
> + of_property_for_each_u32(node, "st,adc-channels", prop, cur, val) {
> + if (val >= ARRAY_SIZE(stm32f4_adc123_channels)) {
> + dev_err(&indio_dev->dev, "Invalid channel %d\n", val);
> + return -EINVAL;
> + }
> + stm32_adc_chan_init_one(indio_dev, &channels[scan_index],
> + &stm32f4_adc123_channels[val],
> + scan_index);
> + scan_index++;
> + }
> +
> + indio_dev->num_channels = scan_index;
> + indio_dev->channels = channels;
> +
> + return 0;
> +}
> +
> +static int stm32_adc_probe(struct platform_device *pdev)
> +{
> + struct iio_dev *indio_dev;
> + struct stm32_adc *adc;
> + int ret;
> +
> + if (!pdev->dev.of_node)
> + return -ENODEV;
> +
> + indio_dev = devm_iio_device_alloc(&pdev->dev, sizeof(*adc));
> + if (!indio_dev)
> + return -ENOMEM;
> +
> + adc = iio_priv(indio_dev);
> + adc->common = dev_get_drvdata(pdev->dev.parent);
> + spin_lock_init(&adc->lock);
> + init_completion(&adc->completion);
> +
> + indio_dev->name = dev_name(&pdev->dev);
> + indio_dev->dev.parent = &pdev->dev;
> + indio_dev->dev.of_node = pdev->dev.of_node;
> + indio_dev->info = &stm32_adc_iio_info;
> + indio_dev->modes = INDIO_DIRECT_MODE;
> +
> + platform_set_drvdata(pdev, adc);
> +
> + ret = of_property_read_u32(pdev->dev.of_node, "reg", &adc->offset);
> + if (ret != 0) {
> + dev_err(&pdev->dev, "missing reg property\n");
> + return -EINVAL;
> + }
> +
> + adc->irq = platform_get_irq(pdev, 0);
> + if (adc->irq < 0) {
> + dev_err(&pdev->dev, "failed to get irq\n");
> + return adc->irq;
> + }
> +
> + ret = devm_request_irq(&pdev->dev, adc->irq, stm32_adc_isr,
> + 0, pdev->name, adc);
> + if (ret) {
> + dev_err(&pdev->dev, "failed to request IRQ\n");
> + return ret;
> + }
> +
> + adc->clk = devm_clk_get(&pdev->dev, NULL);
> + if (IS_ERR(adc->clk)) {
Could it concievably be deferred? Would be happier if this explicitly
checked for -ENODEV or whatever gets returned when not clock has
been specified.
> + adc->clk = NULL;
> + dev_dbg(&pdev->dev, "No child clk found\n");
> + } else {
> + ret = clk_prepare_enable(adc->clk);
> + if (ret < 0) {
> + dev_err(&pdev->dev, "clk enable failed\n");
> + return ret;
> + }
> + }
> +
> + ret = stm32_adc_chan_of_init(indio_dev);
> + if (ret < 0)
> + goto err_clk_disable;
> +
> + ret = devm_iio_device_register(&pdev->dev, indio_dev);
This use of devm registration is going to cause a race in the remove.
The userspace interface will not be removed until after the remove
function has run. That disables the clock thus leaving us a window
where we could try and access the device with no clock enabled.
Basic rule of thumb is that use of devm must not effect the ordering
of unrolling what you do in probe when it comes to remove.
(which more or less means that you can't use devm_iio_device_register
unless you have no remove at all).
> + if (ret) {
> + dev_err(&pdev->dev, "iio dev register failed\n");
> + goto err_clk_disable;
> + }
> +
> + return 0;
> +
> +err_clk_disable:
> + if (adc->clk)
> + clk_disable_unprepare(adc->clk);
> +
> + return ret;
> +}
> +
> +static int stm32_adc_remove(struct platform_device *pdev)
> +{
> + struct stm32_adc *adc = platform_get_drvdata(pdev);
> +
> + if (adc->clk)
> + clk_disable_unprepare(adc->clk);
> +
> + return 0;
> +}
> +
> +static const struct of_device_id stm32_adc_of_match[] = {
> + { .compatible = "st,stm32f4-adc" },
> + {},
> +};
> +MODULE_DEVICE_TABLE(of, stm32_adc_of_match);
> +
> +static struct platform_driver stm32_adc_driver = {
> + .probe = stm32_adc_probe,
> + .remove = stm32_adc_remove,
> + .driver = {
> + .name = "stm32-adc",
> + .of_match_table = stm32_adc_of_match,
> + },
> +};
> +module_platform_driver(stm32_adc_driver);
> +
> +MODULE_AUTHOR("Fabrice Gasnier <fabrice.gasnier at st.com>");
> +MODULE_DESCRIPTION("STMicroelectronics STM32 ADC IIO driver");
> +MODULE_LICENSE("GPL v2");
> +MODULE_ALIAS("platform:stm32-adc");
>
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