[PATCH v2 3/6] iio: adc: Add support for STM32 ADC
From: Fabrice Gasnier
Date: Thu Nov 10 2016 - 11:20:50 EST
This patch adds support for STMicroelectronics STM32 MCU's analog to
digital converter.
Signed-off-by: Fabrice Gasnier <fabrice.gasnier@xxxxxx>
---
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@xxxxxx>.
+ *
+ * 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 */
+#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);
+ break;
+ case IIO_CHAN_INFO_SCALE:
+ *val = adc->common->vref_mv;
+ *val2 = chan->scan_type.realbits;
+ ret = IIO_VAL_FRACTIONAL_LOG2;
+ break;
+ default:
+ 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;
+ }
+
+ 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;
+ 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)) {
+ 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);
+ 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@xxxxxx>");
+MODULE_DESCRIPTION("STMicroelectronics STM32 ADC IIO driver");
+MODULE_LICENSE("GPL v2");
+MODULE_ALIAS("platform:stm32-adc");
--
1.9.1