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iio: adc: ti-ads7950: add GPIO support
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The ADS79XX has GPIO pins that can be used. Add support for the GPIO
pins using the GPIO chip framework.

Signed-off-by: Justin Chen <justinpopo6@gmail.com>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
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Justin Chen authored and Jonathan Cameron committed Apr 4, 2019
1 parent 1381462 commit c97dce7
Showing 1 changed file with 194 additions and 6 deletions.
200 changes: 194 additions & 6 deletions drivers/iio/adc/ti-ads7950.c
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Original file line number Diff line number Diff line change
Expand Up @@ -17,6 +17,7 @@
#include <linux/bitops.h>
#include <linux/device.h>
#include <linux/err.h>
#include <linux/gpio/driver.h>
#include <linux/interrupt.h>
#include <linux/kernel.h>
#include <linux/module.h>
Expand All @@ -36,19 +37,32 @@
*/
#define TI_ADS7950_VA_MV_ACPI_DEFAULT 5000

#define TI_ADS7950_CR_GPIO BIT(14)
#define TI_ADS7950_CR_MANUAL BIT(12)
#define TI_ADS7950_CR_WRITE BIT(11)
#define TI_ADS7950_CR_CHAN(ch) ((ch) << 7)
#define TI_ADS7950_CR_RANGE_5V BIT(6)
#define TI_ADS7950_CR_GPIO_DATA BIT(4)

#define TI_ADS7950_MAX_CHAN 16
#define TI_ADS7950_NUM_GPIOS 4

#define TI_ADS7950_TIMESTAMP_SIZE (sizeof(int64_t) / sizeof(__be16))

/* val = value, dec = left shift, bits = number of bits of the mask */
#define TI_ADS7950_EXTRACT(val, dec, bits) \
(((val) >> (dec)) & ((1 << (bits)) - 1))

#define TI_ADS7950_MAN_CMD(cmd) (TI_ADS7950_CR_MANUAL | (cmd))
#define TI_ADS7950_GPIO_CMD(cmd) (TI_ADS7950_CR_GPIO | (cmd))

/* Manual mode configuration */
#define TI_ADS7950_MAN_CMD_SETTINGS(st) \
(TI_ADS7950_MAN_CMD(TI_ADS7950_CR_WRITE | st->cmd_settings_bitmask))
/* GPIO mode configuration */
#define TI_ADS7950_GPIO_CMD_SETTINGS(st) \
(TI_ADS7950_GPIO_CMD(st->gpio_cmd_settings_bitmask))

struct ti_ads7950_state {
struct spi_device *spi;
struct spi_transfer ring_xfer;
Expand All @@ -58,11 +72,34 @@ struct ti_ads7950_state {

/* Lock to protect the spi xfer buffers */
struct mutex slock;
struct gpio_chip chip;

struct regulator *reg;
unsigned int vref_mv;

unsigned int settings;
/*
* Bitmask of lower 7 bits used for configuration
* These bits only can be written when TI_ADS7950_CR_WRITE
* is set, otherwise it retains its original state.
* [0-3] GPIO signal
* [4] Set following frame to return GPIO signal values
* [5] Powers down device
* [6] Sets Vref range1(2.5v) or range2(5v)
*
* Bits present on Manual/Auto1/Auto2 commands
*/
unsigned int cmd_settings_bitmask;

/*
* Bitmask of GPIO command
* [0-3] GPIO direction
* [4-6] Different GPIO alarm mode configurations
* [7] GPIO 2 as device range input
* [8] GPIO 3 as device power down input
* [9] Reset all registers
* [10-11] N/A
*/
unsigned int gpio_cmd_settings_bitmask;

/*
* DMA (thus cache coherency maintenance) requires the
Expand Down Expand Up @@ -251,7 +288,7 @@ static int ti_ads7950_update_scan_mode(struct iio_dev *indio_dev,

len = 0;
for_each_set_bit(i, active_scan_mask, indio_dev->num_channels) {
cmd = TI_ADS7950_CR_WRITE | TI_ADS7950_CR_CHAN(i) | st->settings;
cmd = TI_ADS7950_MAN_CMD(TI_ADS7950_CR_CHAN(i));
st->tx_buf[len++] = cmd;
}

Expand Down Expand Up @@ -292,8 +329,7 @@ static int ti_ads7950_scan_direct(struct iio_dev *indio_dev, unsigned int ch)
int ret, cmd;

mutex_lock(&st->slock);

cmd = TI_ADS7950_CR_WRITE | TI_ADS7950_CR_CHAN(ch) | st->settings;
cmd = TI_ADS7950_MAN_CMD(TI_ADS7950_CR_CHAN(ch));
st->single_tx = cmd;

ret = spi_sync(st->spi, &st->scan_single_msg);
Expand Down Expand Up @@ -322,7 +358,7 @@ static int ti_ads7950_get_range(struct ti_ads7950_state *st)
vref /= 1000;
}

if (st->settings & TI_ADS7950_CR_RANGE_5V)
if (st->cmd_settings_bitmask & TI_ADS7950_CR_RANGE_5V)
vref *= 2;

return vref;
Expand Down Expand Up @@ -367,6 +403,132 @@ static const struct iio_info ti_ads7950_info = {
.update_scan_mode = ti_ads7950_update_scan_mode,
};

static void ti_ads7950_set(struct gpio_chip *chip, unsigned int offset,
int value)
{
struct ti_ads7950_state *st = gpiochip_get_data(chip);

mutex_lock(&st->slock);

if (value)
st->cmd_settings_bitmask |= BIT(offset);
else
st->cmd_settings_bitmask &= ~BIT(offset);

st->single_tx = TI_ADS7950_MAN_CMD_SETTINGS(st);
spi_sync(st->spi, &st->scan_single_msg);

mutex_unlock(&st->slock);
}

static int ti_ads7950_get(struct gpio_chip *chip, unsigned int offset)
{
struct ti_ads7950_state *st = gpiochip_get_data(chip);
int ret;

mutex_lock(&st->slock);

/* If set as output, return the output */
if (st->gpio_cmd_settings_bitmask & BIT(offset)) {
ret = st->cmd_settings_bitmask & BIT(offset);
goto out;
}

/* GPIO data bit sets SDO bits 12-15 to GPIO input */
st->cmd_settings_bitmask |= TI_ADS7950_CR_GPIO_DATA;
st->single_tx = TI_ADS7950_MAN_CMD_SETTINGS(st);
ret = spi_sync(st->spi, &st->scan_single_msg);
if (ret)
goto out;

ret = ((st->single_rx >> 12) & BIT(offset)) ? 1 : 0;

/* Revert back to original settings */
st->cmd_settings_bitmask &= ~TI_ADS7950_CR_GPIO_DATA;
st->single_tx = TI_ADS7950_MAN_CMD_SETTINGS(st);
ret = spi_sync(st->spi, &st->scan_single_msg);
if (ret)
goto out;

out:
mutex_unlock(&st->slock);

return ret;
}

static int ti_ads7950_get_direction(struct gpio_chip *chip,
unsigned int offset)
{
struct ti_ads7950_state *st = gpiochip_get_data(chip);

/* Bitmask is inverted from GPIO framework 0=input/1=output */
return !(st->gpio_cmd_settings_bitmask & BIT(offset));
}

static int _ti_ads7950_set_direction(struct gpio_chip *chip, int offset,
int input)
{
struct ti_ads7950_state *st = gpiochip_get_data(chip);
int ret = 0;

mutex_lock(&st->slock);

/* Only change direction if needed */
if (input && (st->gpio_cmd_settings_bitmask & BIT(offset)))
st->gpio_cmd_settings_bitmask &= ~BIT(offset);
else if (!input && !(st->gpio_cmd_settings_bitmask & BIT(offset)))
st->gpio_cmd_settings_bitmask |= BIT(offset);
else
goto out;

st->single_tx = TI_ADS7950_GPIO_CMD_SETTINGS(st);
ret = spi_sync(st->spi, &st->scan_single_msg);

out:
mutex_unlock(&st->slock);

return ret;
}

static int ti_ads7950_direction_input(struct gpio_chip *chip,
unsigned int offset)
{
return _ti_ads7950_set_direction(chip, offset, 1);
}

static int ti_ads7950_direction_output(struct gpio_chip *chip,
unsigned int offset, int value)
{
ti_ads7950_set(chip, offset, value);

return _ti_ads7950_set_direction(chip, offset, 0);
}

static int ti_ads7950_init_hw(struct ti_ads7950_state *st)
{
int ret = 0;

mutex_lock(&st->slock);

/* Settings for Manual/Auto1/Auto2 commands */
/* Default to 5v ref */
st->cmd_settings_bitmask = TI_ADS7950_CR_RANGE_5V;
st->single_tx = TI_ADS7950_MAN_CMD_SETTINGS(st);
ret = spi_sync(st->spi, &st->scan_single_msg);
if (ret)
goto out;

/* Settings for GPIO command */
st->gpio_cmd_settings_bitmask = 0x0;
st->single_tx = TI_ADS7950_GPIO_CMD_SETTINGS(st);
ret = spi_sync(st->spi, &st->scan_single_msg);

out:
mutex_unlock(&st->slock);

return ret;
}

static int ti_ads7950_probe(struct spi_device *spi)
{
struct ti_ads7950_state *st;
Expand All @@ -391,7 +553,6 @@ static int ti_ads7950_probe(struct spi_device *spi)
spi_set_drvdata(spi, indio_dev);

st->spi = spi;
st->settings = TI_ADS7950_CR_MANUAL | TI_ADS7950_CR_RANGE_5V;

info = &ti_ads7950_chip_info[spi_get_device_id(spi)->driver_data];

Expand Down Expand Up @@ -459,14 +620,40 @@ static int ti_ads7950_probe(struct spi_device *spi)
goto error_disable_reg;
}

ret = ti_ads7950_init_hw(st);
if (ret) {
dev_err(&spi->dev, "Failed to init adc chip\n");
goto error_cleanup_ring;
}

ret = iio_device_register(indio_dev);
if (ret) {
dev_err(&spi->dev, "Failed to register iio device\n");
goto error_cleanup_ring;
}

/* Add GPIO chip */
st->chip.label = dev_name(&st->spi->dev);
st->chip.parent = &st->spi->dev;
st->chip.owner = THIS_MODULE;
st->chip.base = -1;
st->chip.ngpio = TI_ADS7950_NUM_GPIOS;
st->chip.get_direction = ti_ads7950_get_direction;
st->chip.direction_input = ti_ads7950_direction_input;
st->chip.direction_output = ti_ads7950_direction_output;
st->chip.get = ti_ads7950_get;
st->chip.set = ti_ads7950_set;

ret = gpiochip_add_data(&st->chip, st);
if (ret) {
dev_err(&spi->dev, "Failed to init GPIOs\n");
goto error_iio_device;
}

return 0;

error_iio_device:
iio_device_unregister(indio_dev);
error_cleanup_ring:
iio_triggered_buffer_cleanup(indio_dev);
error_disable_reg:
Expand All @@ -482,6 +669,7 @@ static int ti_ads7950_remove(struct spi_device *spi)
struct iio_dev *indio_dev = spi_get_drvdata(spi);
struct ti_ads7950_state *st = iio_priv(indio_dev);

gpiochip_remove(&st->chip);
iio_device_unregister(indio_dev);
iio_triggered_buffer_cleanup(indio_dev);
regulator_disable(st->reg);
Expand Down

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