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iio:imu:adis: Add paging support
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Some of the newer generation devices from the ADIS16XXX series have more
registers than what can be supported with the current register addressing
scheme. These devices implement register paging to support a larger register
range. Each page is 128 registers large and the currently active page can be
selected via register 0x00 in each page. This patch implements transparent
paging inside the common adis library. The register read/write interface stays
the same and when a register is accessed the library automatically switches to
the correct page if it is not already selected. The page number is encoded in
the upper bits of the register number, e.g. register 0x5 of page 1 is 0x85.

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>
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Lars-Peter Clausen authored and Jonathan Cameron committed Nov 20, 2012
1 parent 9caed0d commit 484a0bf
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Showing 3 changed files with 77 additions and 18 deletions.
70 changes: 54 additions & 16 deletions drivers/iio/imu/adis.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -30,6 +30,7 @@
int adis_write_reg(struct adis *adis, unsigned int reg,
unsigned int value, unsigned int size)
{
unsigned int page = reg / ADIS_PAGE_SIZE;
int ret, i;
struct spi_message msg;
struct spi_transfer xfers[] = {
Expand All @@ -56,39 +57,53 @@ int adis_write_reg(struct adis *adis, unsigned int reg,
.bits_per_word = 8,
.len = 2,
.delay_usecs = adis->data->write_delay,
}, {
.tx_buf = adis->tx + 8,
.bits_per_word = 8,
.len = 2,
.delay_usecs = adis->data->write_delay,
},
};

mutex_lock(&adis->txrx_lock);

spi_message_init(&msg);

if (adis->current_page != page) {
adis->tx[0] = ADIS_WRITE_REG(ADIS_REG_PAGE_ID);
adis->tx[1] = page;
spi_message_add_tail(&xfers[0], &msg);
}

switch (size) {
case 4:
adis->tx[6] = ADIS_WRITE_REG(reg + 3);
adis->tx[7] = (value >> 24) & 0xff;
adis->tx[4] = ADIS_WRITE_REG(reg + 2);
adis->tx[5] = (value >> 16) & 0xff;
adis->tx[8] = ADIS_WRITE_REG(reg + 3);
adis->tx[9] = (value >> 24) & 0xff;
adis->tx[6] = ADIS_WRITE_REG(reg + 2);
adis->tx[7] = (value >> 16) & 0xff;
case 2:
adis->tx[2] = ADIS_WRITE_REG(reg + 1);
adis->tx[3] = (value >> 8) & 0xff;
adis->tx[4] = ADIS_WRITE_REG(reg + 1);
adis->tx[5] = (value >> 8) & 0xff;
case 1:
adis->tx[0] = ADIS_WRITE_REG(reg);
adis->tx[1] = value & 0xff;
adis->tx[2] = ADIS_WRITE_REG(reg);
adis->tx[3] = value & 0xff;
break;
default:
ret = -EINVAL;
goto out_unlock;
}

xfers[size - 1].cs_change = 0;
xfers[size].cs_change = 0;

for (i = 0; i < size; i++)
for (i = 1; i <= size; i++)
spi_message_add_tail(&xfers[i], &msg);

ret = spi_sync(adis->spi, &msg);
if (ret) {
dev_err(&adis->spi->dev, "Failed to write register 0x%02X: %d\n",
reg, ret);
} else {
adis->current_page = page;
}

out_unlock:
Expand All @@ -107,6 +122,7 @@ EXPORT_SYMBOL_GPL(adis_write_reg);
int adis_read_reg(struct adis *adis, unsigned int reg,
unsigned int *val, unsigned int size)
{
unsigned int page = reg / ADIS_PAGE_SIZE;
struct spi_message msg;
int ret;
struct spi_transfer xfers[] = {
Expand All @@ -115,9 +131,15 @@ int adis_read_reg(struct adis *adis, unsigned int reg,
.bits_per_word = 8,
.len = 2,
.cs_change = 1,
.delay_usecs = adis->data->read_delay,
.delay_usecs = adis->data->write_delay,
}, {
.tx_buf = adis->tx + 2,
.bits_per_word = 8,
.len = 2,
.cs_change = 1,
.delay_usecs = adis->data->read_delay,
}, {
.tx_buf = adis->tx + 4,
.rx_buf = adis->rx,
.bits_per_word = 8,
.len = 2,
Expand All @@ -134,16 +156,22 @@ int adis_read_reg(struct adis *adis, unsigned int reg,
mutex_lock(&adis->txrx_lock);
spi_message_init(&msg);

if (adis->current_page != page) {
adis->tx[0] = ADIS_WRITE_REG(ADIS_REG_PAGE_ID);
adis->tx[1] = page;
spi_message_add_tail(&xfers[0], &msg);
}

switch (size) {
case 4:
adis->tx[0] = ADIS_READ_REG(reg + 2);
adis->tx[1] = 0;
spi_message_add_tail(&xfers[0], &msg);
case 2:
adis->tx[2] = ADIS_READ_REG(reg);
adis->tx[2] = ADIS_READ_REG(reg + 2);
adis->tx[3] = 0;
spi_message_add_tail(&xfers[1], &msg);
case 2:
adis->tx[4] = ADIS_READ_REG(reg);
adis->tx[5] = 0;
spi_message_add_tail(&xfers[2], &msg);
spi_message_add_tail(&xfers[3], &msg);
break;
default:
ret = -EINVAL;
Expand All @@ -155,6 +183,8 @@ int adis_read_reg(struct adis *adis, unsigned int reg,
dev_err(&adis->spi->dev, "Failed to read register 0x%02X: %d\n",
reg, ret);
goto out_unlock;
} else {
adis->current_page = page;
}

switch (size) {
Expand Down Expand Up @@ -390,6 +420,14 @@ int adis_init(struct adis *adis, struct iio_dev *indio_dev,
adis->data = data;
iio_device_set_drvdata(indio_dev, adis);

if (data->has_paging) {
/* Need to set the page before first read/write */
adis->current_page = -1;
} else {
/* Page will always be 0 */
adis->current_page = 0;
}

return adis_enable_irq(adis, false);
}
EXPORT_SYMBOL_GPL(adis_init);
Expand Down
15 changes: 15 additions & 0 deletions drivers/iio/imu/adis_buffer.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -83,10 +83,25 @@ static irqreturn_t adis_trigger_handler(int irq, void *p)
if (!adis->buffer)
return -ENOMEM;

if (adis->data->has_paging) {
mutex_lock(&adis->txrx_lock);
if (adis->current_page != 0) {
adis->tx[0] = ADIS_WRITE_REG(ADIS_REG_PAGE_ID);
adis->tx[1] = 0;
spi_write(adis->spi, adis->tx, 2);
}
}

ret = spi_sync(adis->spi, &adis->msg);
if (ret)
dev_err(&adis->spi->dev, "Failed to read data: %d", ret);


if (adis->data->has_paging) {
adis->current_page = 0;
mutex_unlock(&adis->txrx_lock);
}

/* Guaranteed to be aligned with 8 byte boundary */
if (indio_dev->scan_timestamp) {
void *b = adis->buffer + indio_dev->scan_bytes - sizeof(s64);
Expand Down
10 changes: 8 additions & 2 deletions include/linux/iio/imu/adis.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -14,8 +14,11 @@
#include <linux/interrupt.h>
#include <linux/iio/types.h>

#define ADIS_WRITE_REG(reg) (0x80 | (reg))
#define ADIS_READ_REG(reg) (reg)
#define ADIS_WRITE_REG(reg) ((0x80 | (reg)))
#define ADIS_READ_REG(reg) ((reg) & 0x7f)

#define ADIS_PAGE_SIZE 0x80
#define ADIS_REG_PAGE_ID 0x00

/**
* struct adis_data - ADIS chip variant specific data
Expand All @@ -40,6 +43,8 @@ struct adis_data {

const char * const *status_error_msgs;
unsigned int status_error_mask;

bool has_paging;
};

struct adis {
Expand All @@ -51,6 +56,7 @@ struct adis {
struct mutex txrx_lock;
struct spi_message msg;
struct spi_transfer *xfer;
unsigned int current_page;
void *buffer;

uint8_t tx[10] ____cacheline_aligned;
Expand Down

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