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iio: adc: Add support for STM32 ADC 

This patch adds support for STMicroelectronics STM32 MCU's analog to
digital converter.

Signed-off-by: Fabrice Gasnier <fabrice.gasnier@st.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>
This commit is contained in:
Fabrice Gasnier 2016-11-15 16:30:58 +01:00 committed by Jonathan Cameron
parent 1add698802
commit 0f883b223a
3 changed files with 529 additions and 0 deletions
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10
drivers/iio/adc/Kconfig
View File

@ -453,6 +453,16 @@ config STM32_ADC_CORE
This driver can also be built as a module. If so, the module
will be called stm32-adc-core.
config STM32_ADC
tristate "STMicroelectronics STM32 adc"
depends on STM32_ADC_CORE
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

1
drivers/iio/adc/Makefile
View File

@ -44,6 +44,7 @@ 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_CORE) += stm32-adc-core.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

518
drivers/iio/adc/stm32-adc.c Normal file
View File

@ -0,0 +1,518 @@
/*
* This file is part of STM32 ADC driver
*
* Copyright (C) 2016, STMicroelectronics - All Rights Reserved
* Author: Fabrice Gasnier <fabrice.gasnier@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/module.h>
#include <linux/platform_device.h>
#include <linux/of.h>
#include "stm32-adc-core.h"
/* STM32F4 - Registers for each ADC instance */
#define STM32F4_ADC_SR 0x00
#define STM32F4_ADC_CR1 0x04
#define STM32F4_ADC_CR2 0x08
#define STM32F4_ADC_SMPR1 0x0C
#define STM32F4_ADC_SMPR2 0x10
#define STM32F4_ADC_HTR 0x24
#define STM32F4_ADC_LTR 0x28
#define STM32F4_ADC_SQR1 0x2C
#define STM32F4_ADC_SQR2 0x30
#define STM32F4_ADC_SQR3 0x34
#define STM32F4_ADC_JSQR 0x38
#define STM32F4_ADC_JDR1 0x3C
#define STM32F4_ADC_JDR2 0x40
#define STM32F4_ADC_JDR3 0x44
#define STM32F4_ADC_JDR4 0x48
#define STM32F4_ADC_DR 0x4C
/* STM32F4_ADC_SR - bit fields */
#define STM32F4_STRT BIT(4)
#define STM32F4_EOC BIT(1)
/* STM32F4_ADC_CR1 - bit fields */
#define STM32F4_SCAN BIT(8)
#define STM32F4_EOCIE BIT(5)
/* STM32F4_ADC_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_ADC_SQR1 - bit fields */
#define STM32F4_L_SHIFT 20
#define STM32F4_L_MASK GENMASK(23, 20)
/* STM32F4_ADC_SQR3 - bit fields */
#define STM32F4_SQ1_SHIFT 0
#define STM32F4_SQ1_MASK GENMASK(4, 0)
#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: 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 u16 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_ADC_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_ADC_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_ADC_CR1, STM32F4_SCAN);
stm32_adc_set_bits(adc, STM32F4_ADC_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_ADC_CR2) & STM32F4_EXTEN_MASK))
stm32_adc_set_bits(adc, STM32F4_ADC_CR2, STM32F4_SWSTART);
}
static void stm32_adc_stop_conv(struct stm32_adc *adc)
{
stm32_adc_clr_bits(adc, STM32F4_ADC_CR2, STM32F4_EXTEN_MASK);
stm32_adc_clr_bits(adc, STM32F4_ADC_SR, STM32F4_STRT);
stm32_adc_clr_bits(adc, STM32F4_ADC_CR1, STM32F4_SCAN);
stm32_adc_clr_bits(adc, STM32F4_ADC_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_ADC_SQR3);
val &= ~STM32F4_SQ1_MASK;
val |= chan->channel << STM32F4_SQ1_SHIFT;
stm32_adc_writel(adc, STM32F4_ADC_SQR3, val);
/* Set regular sequence len (0 for 1 conversion) */
stm32_adc_clr_bits(adc, STM32F4_ADC_SQR1, STM32F4_L_MASK);
/* Trigger detection disabled (conversion can be launched in SW) */
stm32_adc_clr_bits(adc, STM32F4_ADC_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) {
ret = -ETIMEDOUT;
} else if (timeout < 0) {
ret = timeout;
} 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;
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 ret;
case IIO_CHAN_INFO_SCALE:
*val = adc->common->vref_mv;
*val2 = chan->scan_type.realbits;
return IIO_VAL_FRACTIONAL_LOG2;
default:
return -EINVAL;
}
}
static irqreturn_t stm32_adc_isr(int irq, void *data)
{
struct stm32_adc *adc = data;
u32 status = stm32_adc_readl(adc, STM32F4_ADC_SR);
if (status & STM32F4_EOC) {
*adc->buffer = stm32_adc_readw(adc, STM32F4_ADC_DR);
complete(&adc->completion);
return IRQ_HANDLED;
}
return IRQ_NONE;
}
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->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)) {
dev_err(&pdev->dev, "Can't get clock\n");
return PTR_ERR(adc->clk);
}
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 = iio_device_register(indio_dev);
if (ret) {
dev_err(&pdev->dev, "iio dev register failed\n");
goto err_clk_disable;
}
return 0;
err_clk_disable:
clk_disable_unprepare(adc->clk);
return ret;
}
static int stm32_adc_remove(struct platform_device *pdev)
{
struct stm32_adc *adc = platform_get_drvdata(pdev);
struct iio_dev *indio_dev = iio_priv_to_dev(adc);
iio_device_unregister(indio_dev);
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@st.com>");
MODULE_DESCRIPTION("STMicroelectronics STM32 ADC IIO driver");
MODULE_LICENSE("GPL v2");
MODULE_ALIAS("platform:stm32-adc");