[PATCH v5 5/8] iio: adc: add STMPE ADC driver using IIO framework

Philippe Schenker
2018-12-21T13:47:09Z

From: Stefan Agner <stefan@agner.ch>

This adds an ADC driver for the STMPE device using the industrial
input/output interface. The driver supports raw reading of values.
The driver depends on the MFD STMPE driver. If the touchscreen
block is enabled too, only four of the 8 ADC channels are available.

Signed-off-by: Stefan Agner <stefan@agner.ch>
Signed-off-by: Max Krummenacher <max.krummenacher@toradex.com>
Signed-off-by: Philippe Schenker <philippe.schenker@toradex.com>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

---

Changes in v5:
- Removed devm_add_action_or_reset
- Changed iio_device_register to devm_iio_device_register
- Added Jonathan Cameron's Reviewed-by
- Added correct author of commit, as this changed by accident

Changes in v4:
- Moved MFD changes to a precursor patch
- Moved stmpe-ts changes to a precursor patch
- Created stmpe_read_temp and stmpe_read_voltage functions to make
read_raw more readable
- Added local lock instead of using indio_dev's mlock
- Use be16_to_cpu() macro instead of bitshifting
- Added stmpe_enable again to stmpe_adc_init_hw
- Use devm_add_action_or_reset to get rid of the remove function
(I tested if that actually works)

Changes in v3:
- Removed COMPILE_TEST from dependings in Kconfig
- Removed stmpe_adc_get_platform_info() function and integrated the
few code lines in the other function

Changes in v2:
- Code formatting
- Removed unused includes
- Defined the macro STMPE_START_ONE_TEMP_CONV with other macros.
- Added new macro that defines the channel of the temperature sensor.
Took new name for STMPE_MAX_ADC->STMPE_ADC_LAST_NR and used it
throughout the code for better readability.
- Added mutex_unlock where missing.

drivers/iio/adc/Kconfig | 7 +
drivers/iio/adc/Makefile | 1 +
drivers/iio/adc/stmpe-adc.c | 363 ++++++++++++++++++++++++++++++++++++
3 files changed, 371 insertions(+)
create mode 100644 drivers/iio/adc/stmpe-adc.c

diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
index a52fea8749a9..224f2067494d 100644
--- a/drivers/iio/adc/Kconfig
+++ b/drivers/iio/adc/Kconfig
@@ -734,6 +734,13 @@ config STM32_DFSDM_ADC
This driver can also be built as a module. If so, the module
will be called stm32-dfsdm-adc.

+config STMPE_ADC
+ tristate "STMicroelectronics STMPE ADC driver"
+ depends on OF && MFD_STMPE
+ help
+ Say yes here to build support for ST Microelectronics STMPE
+ built-in ADC block (stmpe811).
+
config STX104
tristate "Apex Embedded Systems STX104 driver"
depends on PC104 && X86
diff --git a/drivers/iio/adc/Makefile b/drivers/iio/adc/Makefile
index a6e6a0b659e2..cba889c30bf9 100644
--- a/drivers/iio/adc/Makefile
+++ b/drivers/iio/adc/Makefile
@@ -69,6 +69,7 @@ obj-$(CONFIG_STM32_ADC_CORE) += stm32-adc-core.o
obj-$(CONFIG_STM32_ADC) += stm32-adc.o
obj-$(CONFIG_STM32_DFSDM_CORE) += stm32-dfsdm-core.o
obj-$(CONFIG_STM32_DFSDM_ADC) += stm32-dfsdm-adc.o
+obj-$(CONFIG_STMPE_ADC) += stmpe-adc.o
obj-$(CONFIG_TI_ADC081C) += ti-adc081c.o
obj-$(CONFIG_TI_ADC0832) += ti-adc0832.o
obj-$(CONFIG_TI_ADC084S021) += ti-adc084s021.o
diff --git a/drivers/iio/adc/stmpe-adc.c b/drivers/iio/adc/stmpe-adc.c
new file mode 100644
index 000000000000..37f4b74a5d32
--- /dev/null
+++ b/drivers/iio/adc/stmpe-adc.c
@@ -0,0 +1,363 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * STMicroelectronics STMPE811 IIO ADC Driver
+ *
+ * 4 channel, 10/12-bit ADC
+ *
+ * Copyright (C) 2013-2018 Toradex AG <stefan.agner@toradex.com>
+ */
+
+#include <linux/completion.h>
+#include <linux/err.h>
+#include <linux/iio/iio.h>
+#include <linux/interrupt.h>
+#include <linux/kernel.h>
+#include <linux/mfd/stmpe.h>
+#include <linux/module.h>
+#include <linux/of_platform.h>
+#include <linux/platform_device.h>
+#include <linux/device.h>
+
+#define STMPE_REG_INT_STA 0x0B
+#define STMPE_REG_ADC_INT_EN 0x0E
+#define STMPE_REG_ADC_INT_STA 0x0F
+
+#define STMPE_REG_ADC_CTRL1 0x20
+#define STMPE_REG_ADC_CTRL2 0x21
+#define STMPE_REG_ADC_CAPT 0x22
+#define STMPE_REG_ADC_DATA_CH(channel) (0x30 + 2 * (channel))
+
+#define STMPE_REG_TEMP_CTRL 0x60
+#define STMPE_TEMP_CTRL_ENABLE BIT(0)
+#define STMPE_TEMP_CTRL_ACQ BIT(1)
+#define STMPE_TEMP_CTRL_THRES_EN BIT(3)
+#define STMPE_START_ONE_TEMP_CONV (STMPE_TEMP_CTRL_ENABLE | \
+ STMPE_TEMP_CTRL_ACQ | \
+ STMPE_TEMP_CTRL_THRES_EN)
+#define STMPE_REG_TEMP_DATA 0x61
+#define STMPE_REG_TEMP_TH 0x63
+#define STMPE_ADC_LAST_NR 7
+#define STMPE_TEMP_CHANNEL (STMPE_ADC_LAST_NR + 1)
+
+#define STMPE_ADC_CH(channel) ((1 << (channel)) & 0xff)
+
+#define STMPE_ADC_TIMEOUT msecs_to_jiffies(1000)
+
+struct stmpe_adc {
+ struct stmpe *stmpe;
+ struct clk *clk;
+ struct device *dev;
+ struct mutex lock;
+
+ /* We are allocating plus one for the temperature channel */
+ struct iio_chan_spec stmpe_adc_iio_channels[STMPE_ADC_LAST_NR + 2];
+
+ struct completion completion;
+
+ u8 channel;
+ u32 value;
+};
+
+static int stmpe_read_voltage(struct stmpe_adc *info,
+ struct iio_chan_spec const *chan, int *val)
+{
+ long ret;
+
+ mutex_lock(&info->lock);
+
+ info->channel = (u8)chan->channel;
+
+ if (info->channel > STMPE_ADC_LAST_NR) {
+ mutex_unlock(&info->lock);
+ return -EINVAL;
+ }
+
+ stmpe_reg_write(info->stmpe, STMPE_REG_ADC_INT_EN,
+ STMPE_ADC_CH(info->channel));
+
+ stmpe_reg_write(info->stmpe, STMPE_REG_ADC_CAPT,
+ STMPE_ADC_CH(info->channel));
+
+ *val = info->value;
+
+ ret = wait_for_completion_interruptible_timeout
+ (&info->completion, STMPE_ADC_TIMEOUT);
+
+ if (ret <= 0) {
+ mutex_unlock(&info->lock);
+ if (ret == 0)
+ return -ETIMEDOUT;
+ else
+ return ret;
+ }
+
+ *val = info->value;
+
+ mutex_unlock(&info->lock);
+
+ return 0;
+}
+
+static int stmpe_read_temp(struct stmpe_adc *info,
+ struct iio_chan_spec const *chan, int *val)
+{
+ long ret;
+
+ mutex_lock(&info->lock);
+
+ info->channel = (u8)chan->channel;
+
+ if (info->channel != STMPE_TEMP_CHANNEL) {
+ mutex_unlock(&info->lock);
+ return -EINVAL;
+ }
+
+ stmpe_reg_write(info->stmpe, STMPE_REG_TEMP_CTRL,
+ STMPE_START_ONE_TEMP_CONV);
+
+ ret = wait_for_completion_interruptible_timeout
+ (&info->completion, STMPE_ADC_TIMEOUT);
+
+ if (ret <= 0) {
+ mutex_unlock(&info->lock);
+ if (ret == 0)
+ return -ETIMEDOUT;
+ else
+ return ret;
+ }
+
+ /*
+ * absolute temp = +V3.3 * value /7.51 [K]
+ * scale to [milli °C]
+ */
+ *val = ((449960l * info->value) / 1024l) - 273150;
+
+ mutex_unlock(&info->lock);
+
+ return 0;
+}
+
+static int stmpe_read_raw(struct iio_dev *indio_dev,
+ struct iio_chan_spec const *chan,
+ int *val,
+ int *val2,
+ long mask)
+{
+ struct stmpe_adc *info = iio_priv(indio_dev);
+ long ret;
+
+ switch (mask) {
+ case IIO_CHAN_INFO_RAW:
+ case IIO_CHAN_INFO_PROCESSED:
+
+ switch (chan->type) {
+ case IIO_VOLTAGE:
+ ret = stmpe_read_voltage(info, chan, val);
+ break;
+
+ case IIO_TEMP:
+ ret = stmpe_read_temp(info, chan, val);
+ break;
+ default:
+ return -EINVAL;
+ }
+
+ if (ret < 0)
+ return ret;
+
+ return IIO_VAL_INT;
+
+ case IIO_CHAN_INFO_SCALE:
+ *val = 3300;
+ *val2 = info->stmpe->mod_12b ? 12 : 10;
+ return IIO_VAL_FRACTIONAL_LOG2;
+
+ default:
+ break;
+ }
+
+ return -EINVAL;
+}
+
+static irqreturn_t stmpe_adc_isr(int irq, void *dev_id)
+{
+ struct stmpe_adc *info = (struct stmpe_adc *)dev_id;
+ u16 data;
+
+ if (info->channel > STMPE_TEMP_CHANNEL)
+ return IRQ_NONE;
+
+ if (info->channel <= STMPE_ADC_LAST_NR) {
+ int int_sta;
+
+ int_sta = stmpe_reg_read(info->stmpe, STMPE_REG_ADC_INT_STA);
+
+ /* Is the interrupt relevant */
+ if (!(int_sta & STMPE_ADC_CH(info->channel)))
+ return IRQ_NONE;
+
+ /* Read value */
+ stmpe_block_read(info->stmpe,
+ STMPE_REG_ADC_DATA_CH(info->channel), 2, (u8 *) &data);
+
+ stmpe_reg_write(info->stmpe, STMPE_REG_ADC_INT_STA, int_sta);
+ } else if (info->channel == STMPE_TEMP_CHANNEL) {
+ /* Read value */
+ stmpe_block_read(info->stmpe, STMPE_REG_TEMP_DATA, 2,
+ (u8 *) &data);
+ }
+
+ info->value = (u32) be16_to_cpu(data);
+ complete(&info->completion);
+
+ return IRQ_HANDLED;
+}
+
+static const struct iio_info stmpe_adc_iio_info = {
+ .read_raw = &stmpe_read_raw,
+};
+
+static void stmpe_adc_voltage_chan(struct iio_chan_spec *ics, int chan)
+{
+ ics->type = IIO_VOLTAGE;
+ ics->info_mask_separate = BIT(IIO_CHAN_INFO_RAW);
+ ics->info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE);
+ ics->indexed = 1;
+ ics->channel = chan;
+}
+
+static void stmpe_adc_temp_chan(struct iio_chan_spec *ics, int chan)
+{
+ ics->type = IIO_TEMP;
+ ics->info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED);
+ ics->indexed = 1;
+ ics->channel = chan;
+}
+
+static int stmpe_adc_init_hw(struct stmpe_adc *adc)
+{
+ int ret;
+ struct stmpe *stmpe = adc->stmpe;
+
+ ret = stmpe_enable(stmpe, STMPE_BLOCK_ADC);
+ if (ret) {
+ dev_err(stmpe->dev, "Could not enable clock for ADC\n");
+ return ret;
+ }
+
+ ret = stmpe811_adc_common_init(stmpe);
+ if (ret) {
+ stmpe_disable(stmpe, STMPE_BLOCK_ADC);
+ return ret;
+ }
+
+ /* use temp irq for each conversion completion */
+ stmpe_reg_write(stmpe, STMPE_REG_TEMP_TH, 0);
+ stmpe_reg_write(stmpe, STMPE_REG_TEMP_TH + 1, 0);
+
+ return 0;
+}
+
+static int stmpe_adc_probe(struct platform_device *pdev)
+{
+ struct iio_dev *indio_dev;
+ struct stmpe_adc *info;
+ struct device_node *np;
+ u32 norequest_mask = 0;
+ int irq_temp, irq_adc;
+ int num_chan = 0;
+ int i = 0;
+ int ret;
+
+ irq_adc = platform_get_irq_byname(pdev, "STMPE_ADC");
+ if (irq_adc < 0)
+ return irq_adc;
+
+ indio_dev = devm_iio_device_alloc(&pdev->dev, sizeof(struct stmpe_adc));
+ if (!indio_dev) {
+ dev_err(&pdev->dev, "failed allocating iio device\n");
+ return -ENOMEM;
+ }
+
+ info = iio_priv(indio_dev);
+ mutex_init(&info->lock);
+
+ init_completion(&info->completion);
+ ret = devm_request_threaded_irq(&pdev->dev, irq_adc, NULL,
+ stmpe_adc_isr, IRQF_ONESHOT,
+ "stmpe-adc", info);
+ if (ret < 0) {
+ dev_err(&pdev->dev, "failed requesting irq, irq = %d\n",
+ irq_adc);
+ return ret;
+ }
+
+ irq_temp = platform_get_irq_byname(pdev, "STMPE_TEMP_SENS");
+ if (irq_temp >= 0) {
+ ret = devm_request_threaded_irq(&pdev->dev, irq_temp, NULL,
+ stmpe_adc_isr, IRQF_ONESHOT,
+ "stmpe-adc", info);
+ if (ret < 0)
+ dev_warn(&pdev->dev, "failed requesting irq for"
+ " temp sensor, irq = %d\n", irq_temp);
+ }
+
+ platform_set_drvdata(pdev, indio_dev);
+
+ indio_dev->name = dev_name(&pdev->dev);
+ indio_dev->dev.parent = &pdev->dev;
+ indio_dev->info = &stmpe_adc_iio_info;
+ indio_dev->modes = INDIO_DIRECT_MODE;
+
+ info->stmpe = dev_get_drvdata(pdev->dev.parent);
+
+ np = pdev->dev.of_node;
+
+ if (!np)
+ dev_err(&pdev->dev, "no device tree node found\n");
+
+ of_property_read_u32(np, "st,norequest-mask", &norequest_mask);
+
+ for_each_clear_bit(i, (unsigned long *) &norequest_mask,
+ (STMPE_ADC_LAST_NR + 1)) {
+ stmpe_adc_voltage_chan(&info->stmpe_adc_iio_channels[num_chan], i);
+ num_chan++;
+ }
+ stmpe_adc_temp_chan(&info->stmpe_adc_iio_channels[num_chan], i);
+ num_chan++;
+ indio_dev->channels = info->stmpe_adc_iio_channels;
+ indio_dev->num_channels = num_chan;
+
+ ret = stmpe_adc_init_hw(info);
+ if (ret)
+ return ret;
+
+ return devm_iio_device_register(&pdev->dev, indio_dev);
+}
+
+static int __maybe_unused stmpe_adc_resume(struct device *dev)
+{
+ struct iio_dev *indio_dev = dev_get_drvdata(dev);
+ struct stmpe_adc *info = iio_priv(indio_dev);
+
+ stmpe_adc_init_hw(info);
+
+ return 0;
+}
+
+static SIMPLE_DEV_PM_OPS(stmpe_adc_pm_ops, NULL, stmpe_adc_resume);
+
+static struct platform_driver stmpe_adc_driver = {
+ .probe = stmpe_adc_probe,
+ .driver = {
+ .name = "stmpe-adc",
+ .pm = &stmpe_adc_pm_ops,
+ },
+};
+
+module_platform_driver(stmpe_adc_driver);
+
+MODULE_AUTHOR("Stefan Agner <stefan.agner@toradex.com>");
+MODULE_DESCRIPTION("STMPEXXX ADC driver");
+MODULE_LICENSE("GPL v2");
+MODULE_ALIAS("platform:stmpe-adc");
--
2.19.2