[PATCH v2] iio: add support of the max1027

From: Philippe Reynes
Date: Tue May 20 2014 - 17:27:41 EST

This driver add partial support of the
maxim 1027/1029/1031. Differential mode is not
supported.

It was tested on armadeus apf27 board.

Signed-off-by: Philippe Reynes <tremyfr@xxxxxxxx>
---
.../devicetree/bindings/iio/adc/max1027-adc.txt | 21 +
drivers/staging/iio/adc/Kconfig | 9 +
drivers/staging/iio/adc/Makefile | 1 +
drivers/staging/iio/adc/max1027.c | 553 ++++++++++++++++++++
4 files changed, 584 insertions(+), 0 deletions(-)
create mode 100644 Documentation/devicetree/bindings/iio/adc/max1027-adc.txt
create mode 100644 drivers/staging/iio/adc/max1027.c

Changelog:
v2: (thanks Hartmut Knaack and Jonathan Cameron for the feedback)
- really use devm_*
- use demux magic
- use spi_read and spi_write (instead of spi_sync)
- use define for register (instead of hardcoded value)

diff --git a/Documentation/devicetree/bindings/iio/adc/max1027-adc.txt b/Documentation/devicetree/bindings/iio/adc/max1027-adc.txt
new file mode 100644
index 0000000..2e8b9f3
--- /dev/null
+++ b/Documentation/devicetree/bindings/iio/adc/max1027-adc.txt
@@ -0,0 +1,21 @@
+* Maxim 1027/1029/1031 Analog to Digital Converter (ADC)
+
+Required properties:
+ - compatible: Should be "maxim,max1027" or "maxim,max1029" or "maxim,max1031"
+ - reg: Should contain the ADC SPI address
+ - interrupt-parent: the phandle for the gpio controller
+ - interrupts: (gpio) interrupt to which the chip is connected
+
+Example:
+adc@0 {
+ compatible = "maxim,max1027";
+ reg = <0>;
+ interrupt-parent = <&gpio5>;
+ interrupts = <15 IRQ_TYPE_EDGE_RISING>;
+ pinctrl-names = "default";
+ pinctrl-0 = <&pinctrl_max1027>;
+ /* SPI mode = 0 */
+ spi-cpol = <0>;
+ spi-cpha = <0>;
+ spi-max-frequency = <1000000>;
+};
diff --git a/drivers/staging/iio/adc/Kconfig b/drivers/staging/iio/adc/Kconfig
index 3633298..12a78eb 100644
--- a/drivers/staging/iio/adc/Kconfig
+++ b/drivers/staging/iio/adc/Kconfig
@@ -112,6 +112,15 @@ config LPC32XX_ADC
activate only one via device tree selection. Provides direct access
via sysfs.

+config MAX1027
+ tristate "Maxim max1027 ADC driver"
+ depends on SPI
+ select IIO_BUFFER
+ select IIO_TRIGGERED_BUFFER
+ help
+ Say yes here to build support for Maxim SPI ADC models
+ max1027, max1029 and max1031.
+
config MXS_LRADC
tristate "Freescale i.MX23/i.MX28 LRADC"
depends on ARCH_MXS || COMPILE_TEST
diff --git a/drivers/staging/iio/adc/Makefile b/drivers/staging/iio/adc/Makefile
index 3e9fb14..22fbd0c 100644
--- a/drivers/staging/iio/adc/Makefile
+++ b/drivers/staging/iio/adc/Makefile
@@ -18,5 +18,6 @@ obj-$(CONFIG_AD7816) += ad7816.o
obj-$(CONFIG_AD7192) += ad7192.o
obj-$(CONFIG_AD7280) += ad7280a.o
obj-$(CONFIG_LPC32XX_ADC) += lpc32xx_adc.o
+obj-$(CONFIG_MAX1027) += max1027.o
obj-$(CONFIG_MXS_LRADC) += mxs-lradc.o
obj-$(CONFIG_SPEAR_ADC) += spear_adc.o
diff --git a/drivers/staging/iio/adc/max1027.c b/drivers/staging/iio/adc/max1027.c
new file mode 100644
index 0000000..c2e5936
--- /dev/null
+++ b/drivers/staging/iio/adc/max1027.c
@@ -0,0 +1,553 @@
+ /*
+ * iio/adc/max1027.c
+ * Copyright (C) 2014 Philippe Reynes
+ *
+ * based on linux/drivers/iio/ad7923.c
+ * Copyright 2011 Analog Devices Inc (from AD7923 Driver)
+ * Copyright 2012 CS Systemes d'Information
+ *
+ * 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.
+ *
+ * max1027.c
+ *
+ * Partial support for max1027 and similar chips.
+ */
+
+#include <linux/kernel.h>
+#include <linux/spi/spi.h>
+#include <linux/module.h>
+#include <linux/interrupt.h>
+#include <linux/mutex.h>
+#include <linux/of.h>
+#include <linux/of_gpio.h>
+#include <linux/platform_device.h>
+#include <linux/delay.h>
+#include <linux/gpio.h>
+
+#include <linux/iio/iio.h>
+#include <linux/iio/buffer.h>
+#include <linux/iio/trigger.h>
+#include <linux/iio/trigger_consumer.h>
+#include <linux/iio/triggered_buffer.h>
+
+#define MAX1027_CONV_REG 0x80
+#define MAX1027_SETUP_REG 0x40
+#define MAX1027_AVG_REG 0x20
+#define MAX1027_RST_REG 0x10
+
+/* conversion register */
+#define MAX1027_TEMP 0x01
+#define MAX1027_SCAN_0_N (0x00 << 1)
+#define MAX1027_SCAN_N_M (0x01 << 1)
+#define MAX1027_SCAN_N (0x02 << 1)
+#define MAX1027_NOSCAN (0x03 << 1)
+#define MAX1027_CHAN(n) ((n) << 3)
+
+/* setup register */
+#define MAX1027_UNIPOLAR 0x02
+#define MAX1027_BIPOLAR 0x03
+#define MAX1027_REF_MODE0 (0x00 << 2)
+#define MAX1027_REF_MODE1 (0x01 << 2)
+#define MAX1027_REF_MODE2 (0x02 << 2)
+#define MAX1027_REF_MODE3 (0x03 << 2)
+#define MAX1027_CKS_MODE0 (0x00 << 4)
+#define MAX1027_CKS_MODE1 (0x01 << 4)
+#define MAX1027_CKS_MODE2 (0x02 << 4)
+#define MAX1027_CKS_MODE3 (0x03 << 4)
+
+/* averaging register */
+#define MAX1027_NSCAN_4 0x00
+#define MAX1027_NSCAN_8 0x01
+#define MAX1027_NSCAN_12 0x02
+#define MAX1027_NSCAN_16 0x03
+#define MAX1027_NAVG_4 (0x00 << 2)
+#define MAX1027_NAVG_8 (0x01 << 2)
+#define MAX1027_NAVG_12 (0x02 << 2)
+#define MAX1027_NAVG_16 (0x03 << 2)
+#define MAX1027_AVG_EN (0x01 << 4)
+
+enum max1027_id {
+ max1027,
+ max1029,
+ max1031,
+};
+
+static const struct spi_device_id max1027_id[] = {
+ {"max1027", max1027},
+ {"max1029", max1029},
+ {"max1031", max1031},
+ {}
+};
+MODULE_DEVICE_TABLE(spi, max1027_id);
+
+#ifdef CONFIG_OF
+static const struct of_device_id max1027_adc_dt_ids[] = {
+ { .compatible = "maxim,max1027" },
+ { .compatible = "maxim,max1029" },
+ { .compatible = "maxim,max1031" },
+ {},
+};
+MODULE_DEVICE_TABLE(of, max1027_adc_dt_ids);
+#endif
+
+#define MAX1027_V_CHAN(index) \
+ { \
+ .type = IIO_VOLTAGE, \
+ .indexed = 1, \
+ .channel = index, \
+ .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
+ .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \
+ .address = index, \
+ .scan_index = index+1, \
+ .scan_type = { \
+ .sign = 'u', \
+ .realbits = 10, \
+ .storagebits = 16, \
+ .shift = 2, \
+ .endianness = IIO_BE, \
+ }, \
+ }
+
+#define MAX1027_T_CHAN(index) \
+ { \
+ .type = IIO_TEMP, \
+ .indexed = 0, \
+ .channel = index, \
+ .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
+ .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \
+ .address = index, \
+ .scan_index = index, \
+ .scan_type = { \
+ .sign = 'u', \
+ .realbits = 12, \
+ .storagebits = 16, \
+ .endianness = IIO_BE, \
+ }, \
+ }
+
+static const struct iio_chan_spec max1027_channels[] = {
+ MAX1027_T_CHAN(0),
+ MAX1027_V_CHAN(0),
+ MAX1027_V_CHAN(1),
+ MAX1027_V_CHAN(2),
+ MAX1027_V_CHAN(3),
+ MAX1027_V_CHAN(4),
+ MAX1027_V_CHAN(5),
+ MAX1027_V_CHAN(6),
+ MAX1027_V_CHAN(7)
+};
+
+static const struct iio_chan_spec max1029_channels[] = {
+ MAX1027_T_CHAN(0),
+ MAX1027_V_CHAN(0),
+ MAX1027_V_CHAN(1),
+ MAX1027_V_CHAN(2),
+ MAX1027_V_CHAN(3),
+ MAX1027_V_CHAN(4),
+ MAX1027_V_CHAN(5),
+ MAX1027_V_CHAN(6),
+ MAX1027_V_CHAN(7),
+ MAX1027_V_CHAN(8),
+ MAX1027_V_CHAN(9),
+ MAX1027_V_CHAN(10),
+ MAX1027_V_CHAN(11)
+};
+
+static const struct iio_chan_spec max1031_channels[] = {
+ MAX1027_T_CHAN(0),
+ MAX1027_V_CHAN(0),
+ MAX1027_V_CHAN(1),
+ MAX1027_V_CHAN(2),
+ MAX1027_V_CHAN(3),
+ MAX1027_V_CHAN(4),
+ MAX1027_V_CHAN(5),
+ MAX1027_V_CHAN(6),
+ MAX1027_V_CHAN(7),
+ MAX1027_V_CHAN(8),
+ MAX1027_V_CHAN(9),
+ MAX1027_V_CHAN(10),
+ MAX1027_V_CHAN(11),
+ MAX1027_V_CHAN(12),
+ MAX1027_V_CHAN(13),
+ MAX1027_V_CHAN(14),
+ MAX1027_V_CHAN(15)
+};
+
+static unsigned long max1027_available_scan_masks[] = {
+ 0x00ff,
+ 0x0000,
+};
+
+static unsigned long max1029_available_scan_masks[] = {
+ 0x0fff,
+ 0x0000,
+};
+
+static unsigned long max1031_available_scan_masks[] = {
+ 0xffff,
+ 0x0000,
+};
+
+struct max1027_chip_info {
+ const struct iio_chan_spec *channels;
+ unsigned int num_channels;
+ unsigned long *available_scan_masks;
+};
+
+static const struct max1027_chip_info max1027_chip_info_tbl[] = {
+ [max1027] = {
+ .channels = max1027_channels,
+ .num_channels = ARRAY_SIZE(max1027_channels),
+ .available_scan_masks = max1027_available_scan_masks,
+ },
+ [max1029] = {
+ .channels = max1029_channels,
+ .num_channels = ARRAY_SIZE(max1029_channels),
+ .available_scan_masks = max1029_available_scan_masks,
+ },
+ [max1031] = {
+ .channels = max1031_channels,
+ .num_channels = ARRAY_SIZE(max1031_channels),
+ .available_scan_masks = max1031_available_scan_masks,
+ },
+};
+
+struct max1027_state {
+ struct max1027_chip_info *info;
+ struct spi_device *spi;
+ struct iio_trigger *trig;
+ unsigned short *buffer;
+};
+
+static int max1027_write_register(struct max1027_state *st, unsigned char reg)
+{
+ int ret;
+
+ pr_debug("%s(st = 0x%p, reg = 0x%02x)\n", __func__, st, reg);
+
+ ret = spi_write(st->spi, (void *)&reg, 1);
+ if (ret < 0)
+ pr_err("can't write register\n");
+
+ return ret;
+}
+
+static int max1027_read_value(struct max1027_state *st, int len)
+{
+ int ret;
+
+ pr_debug("%s(st = 0x%p, len = %d)\n", __func__, st, len);
+
+ ret = spi_read(st->spi, st->buffer, len);
+ if (ret < 0)
+ pr_err("can't read value\n");
+
+ return ret;
+}
+
+static int max1027_read_single_value(struct iio_dev *indio_dev,
+ struct iio_chan_spec const *chan,
+ int *val, int *val2, long mask)
+{
+ int ret;
+ unsigned char reg;
+ struct max1027_state *st = iio_priv(indio_dev);
+
+ if (iio_buffer_enabled(indio_dev)) {
+ dev_warn(&indio_dev->dev, "trigger mode already enabled");
+ return -EIO;
+ }
+
+ /* Start acquisition on conversion register write */
+ reg = MAX1027_SETUP_REG | MAX1027_REF_MODE2 | MAX1027_CKS_MODE2;
+ ret = max1027_write_register(st, reg);
+ if (ret < 0) {
+ dev_err(&indio_dev->dev,
+ "Failed to configure setup register\n");
+ return ret;
+ }
+
+ /* Configure conversion register with the requested chan */
+ reg = MAX1027_CONV_REG | MAX1027_CHAN(chan->channel)
+ | MAX1027_NOSCAN | !!(chan->type == IIO_TEMP);
+ ret = max1027_write_register(st, reg);
+ if (ret < 0) {
+ dev_err(&indio_dev->dev,
+ "Failed to configure conversion register\n");
+ return ret;
+ }
+
+ /*
+ * For an unknown reason, when we use the mode "10" (write
+ * conversion register), the it doesn't occur every time.
+ * So we just wait 1 ms.
+ */
+ mdelay(1);
+
+ /* Read result */
+ ret = max1027_read_value(st, (chan->type == IIO_TEMP) ? 4 : 2);
+ if (ret < 0)
+ return ret;
+
+ *val = be16_to_cpu(st->buffer[0]);
+
+ return IIO_VAL_INT;
+}
+
+static int max1027_read_raw(struct iio_dev *indio_dev,
+ struct iio_chan_spec const *chan,
+ int *val, int *val2, long mask)
+{
+ int ret = 0;
+
+ switch (mask) {
+ case IIO_CHAN_INFO_RAW:
+ ret = max1027_read_single_value(indio_dev, chan,
+ val, val2, mask);
+ break;
+ case IIO_CHAN_INFO_SCALE:
+ switch (chan->type) {
+ case IIO_TEMP:
+ *val = 1;
+ *val2 = 8;
+ ret = IIO_VAL_FRACTIONAL;
+ break;
+ case IIO_VOLTAGE:
+ *val = 2500;
+ *val2 = 10;
+ ret = IIO_VAL_FRACTIONAL_LOG2;
+ break;
+ default:
+ ret = -EINVAL;
+ break;
+ };
+ break;
+ default:
+ ret = -EINVAL;
+ break;
+ };
+
+ return ret;
+}
+
+static int max1027_update_scan_mode(struct iio_dev *indio_dev,
+ const unsigned long *scan_mask)
+{
+ pr_debug("%s(indio_dev=0x%p, scan_mask=0x%p)\n",
+ __func__, indio_dev, scan_mask);
+
+ return 0;
+}
+
+static int max1027_debugfs_reg_access(struct iio_dev *indio_dev,
+ unsigned reg, unsigned writeval,
+ unsigned *readval)
+{
+ struct max1027_state *st = iio_priv(indio_dev);
+
+ if (readval != NULL)
+ return -EINVAL;
+
+ return max1027_write_register(st, writeval);
+}
+
+static int max1027_set_trigger_state(struct iio_trigger *trig, bool state)
+{
+ struct iio_dev *indio_dev = iio_trigger_get_drvdata(trig);
+ struct max1027_state *st = iio_priv(indio_dev);
+ unsigned char reg;
+ int ret;
+
+ if (state) {
+ /* Start acquisition on cnvst */
+ reg = MAX1027_SETUP_REG | MAX1027_CKS_MODE0 | MAX1027_REF_MODE2;
+ ret = max1027_write_register(st, reg);
+ if (ret < 0)
+ return ret;
+
+ /* Scan from 0 to max */
+ reg = MAX1027_CONV_REG | MAX1027_CHAN(0)
+ | MAX1027_SCAN_N_M | MAX1027_TEMP;
+ ret = max1027_write_register(st, reg);
+ if (ret < 0)
+ return ret;
+ } else {
+ /* Start acquisition on conversion register write */
+ reg = MAX1027_SETUP_REG | MAX1027_REF_MODE2 | MAX1027_CKS_MODE2;
+ ret = max1027_write_register(st, reg);
+ if (ret < 0)
+ return ret;
+ }
+
+ return 0;
+}
+
+static irqreturn_t max1027_interrupt_handler(int irq, void *private)
+{
+ struct iio_dev *indio_dev = (struct iio_dev *)private;
+
+ pr_debug("%s(irq=%d, private=0x%p)\n", __func__, irq, private);
+
+ if (iio_buffer_enabled(indio_dev))
+ iio_trigger_poll(indio_dev->trig, iio_get_time_ns());
+
+ return IRQ_HANDLED;
+}
+
+static irqreturn_t max1027_trigger_handler(int irq, void *private)
+{
+ struct iio_poll_func *pf = (struct iio_poll_func *)private;
+ struct iio_dev *indio_dev = pf->indio_dev;
+ struct max1027_state *st = iio_priv(indio_dev);
+
+ pr_debug("%s(irq=%d, private=0x%p)\n", __func__, irq, private);
+
+ /* fill buffer with all channel */
+ max1027_read_value(st, indio_dev->masklength * 2);
+
+ iio_push_to_buffers_with_timestamp(indio_dev, st->buffer,
+ iio_get_time_ns());
+
+ iio_trigger_notify_done(indio_dev->trig);
+
+ return IRQ_HANDLED;
+}
+
+static const struct iio_trigger_ops max1027_trigger_ops = {
+ .owner = THIS_MODULE,
+ .set_trigger_state = &max1027_set_trigger_state,
+};
+
+static const struct iio_info max1027_info = {
+ .driver_module = THIS_MODULE,
+ .read_raw = &max1027_read_raw,
+ .update_scan_mode = &max1027_update_scan_mode,
+ .debugfs_reg_access = &max1027_debugfs_reg_access,
+};
+
+static int max1027_probe(struct spi_device *spi)
+{
+ int err;
+ struct iio_dev *indio_dev;
+ struct max1027_state *st;
+
+ pr_debug("%s: probe(spi = 0x%p)\n", __func__, spi);
+
+ /* allocate iio device */
+ indio_dev = devm_iio_device_alloc(&spi->dev,
+ sizeof(struct max1027_state));
+ if (!indio_dev) {
+ pr_err("can't allocate iio device\n");
+ return -ENOMEM;
+ }
+
+ spi_set_drvdata(spi, indio_dev);
+
+ st = iio_priv(indio_dev);
+ st->spi = spi;
+ st->buffer = NULL;
+ st->info = (struct max1027_chip_info *)
+ &max1027_chip_info_tbl[spi_get_device_id(spi)->driver_data];
+
+ /* request irq */
+ err = devm_request_threaded_irq(&spi->dev, spi->irq,
+ max1027_interrupt_handler,
+ NULL,
+ IRQF_TRIGGER_FALLING,
+ spi->dev.driver->name, indio_dev);
+ if (err) {
+ dev_err(&indio_dev->dev, "Failed to allocate IRQ.\n");
+ return err;
+ }
+
+ indio_dev->name = spi_get_device_id(spi)->name;
+ indio_dev->dev.parent = &spi->dev;
+ indio_dev->info = &max1027_info;
+ indio_dev->modes = INDIO_DIRECT_MODE;
+ indio_dev->channels = st->info->channels;
+ indio_dev->num_channels = st->info->num_channels;
+ indio_dev->available_scan_masks = st->info->available_scan_masks;
+
+ /* Allocate buffer (data) */
+ st->buffer = devm_kmalloc(&indio_dev->dev,
+ indio_dev->num_channels * 2,
+ GFP_KERNEL);
+ if (st->buffer == NULL) {
+ dev_err(&indio_dev->dev, "Can't allocate bufffer\n");
+ return -ENOMEM;
+ }
+
+ /* Allocate buffer */
+ err = iio_triggered_buffer_setup(indio_dev, &iio_pollfunc_store_time,
+ &max1027_trigger_handler, NULL);
+ if (err < 0) {
+ dev_err(&indio_dev->dev, "Failed to setup buffer\n");
+ return err;
+ }
+
+ /* Allocate trigger */
+ st->trig = devm_iio_trigger_alloc(&spi->dev, "%s-trigger",
+ indio_dev->name);
+ if (st->trig == NULL) {
+ err = -ENOMEM;
+ dev_err(&indio_dev->dev, "Failed to allocate iio trigger\n");
+ goto fail_trigger_alloc;
+ }
+
+ /* configure and register trigger */
+ st->trig->ops = &max1027_trigger_ops;
+ st->trig->dev.parent = &spi->dev;
+ iio_trigger_set_drvdata(st->trig, indio_dev);
+ iio_trigger_register(st->trig);
+
+ /* Disable averaging */
+ err = max1027_write_register(st, MAX1027_AVG_REG);
+ if (err < 0) {
+ dev_err(&indio_dev->dev, "Failed to configure averaging register\n");
+ goto fail_dev_register;
+ }
+
+ /* Register the device */
+ err = iio_device_register(indio_dev);
+ if (err < 0) {
+ dev_err(&indio_dev->dev, "Failed to register iio device\n");
+ goto fail_dev_register;
+ }
+
+ return 0;
+
+fail_dev_register:
+fail_trigger_alloc:
+ iio_triggered_buffer_cleanup(indio_dev);
+
+ return err;
+}
+
+static int max1027_remove(struct spi_device *spi)
+{
+ struct iio_dev *indio_dev = spi_get_drvdata(spi);
+
+ pr_debug("%s: remove(spi = 0x%p)\n", __func__, spi);
+
+ iio_device_unregister(indio_dev);
+ iio_triggered_buffer_cleanup(indio_dev);
+
+ return 0;
+}
+
+static struct spi_driver max1027_driver = {
+ .driver = {
+ .name = "max1027",
+ .owner = THIS_MODULE,
+ },
+ .probe = max1027_probe,
+ .remove = max1027_remove,
+ .id_table = max1027_id,
+};
+module_spi_driver(max1027_driver);
+
+MODULE_AUTHOR("Philippe Reynes <tremyfr@xxxxxxxx>");
+MODULE_DESCRIPTION("MAX1027/MAX1029/MAX1031 ADC");
+MODULE_LICENSE("GPL v2");
--
1.7.4.4

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