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Staging: IIO: VTI sca3000 series accelerometer driver (spi)

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Example of how a device with a hardware ring buffer is
handled within IIO.

Changes since V2:
* Moved to new registration functions giving much cleaner
  interface.

Signed-off-by: Jonathan Cameron <jic23@cam.ac.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This commit is contained in:
Jonathan Cameron 2009-08-18 18:06:25 +01:00 committed by Greg Kroah-Hartman
parent 7026ea4b52
commit 574fb258d6
6 changed files with 2171 additions and 0 deletions
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8
drivers/staging/iio/accel/Kconfig
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@ -17,3 +17,11 @@ config LIS3L02DQ
Say yes here to build SPI support for the ST microelectronics
accelerometer. The driver supplies direct access via sysfs files
and an event interface via a character device.
config SCA3000
depends on IIO_RING_BUFFER
depends on SPI
tristate "VTI SCA3000 series accelerometers"
help
Say yes here to build support for the VTI SCA3000 series of SPI
accelerometers. These devices use a hardware ring buffer.

3
drivers/staging/iio/accel/Makefile
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@ -5,3 +5,6 @@ obj-$(CONFIG_KXSD9) += kxsd9.o
lis3l02dq-y := lis3l02dq_core.o
obj-$(CONFIG_LIS3L02DQ) += lis3l02dq.o
sca3000-y := sca3000_core.o sca3000_ring.o
obj-$(CONFIG_SCA3000) += sca3000.o

298
drivers/staging/iio/accel/sca3000.h Normal file
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@ -0,0 +1,298 @@
/*
* sca3000.c -- support VTI sca3000 series accelerometers
* via SPI
*
* Copyright (c) 2007 Jonathan Cameron <jic23@cam.ac.uk>
*
* Partly based upon tle62x0.c
*
* 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.
*
* Initial mode is direct measurement.
*
* Untested things
*
* Temperature reading (the e05 I'm testing with doesn't have a sensor)
*
* Free fall detection mode - supported but untested as I'm not droping my
* dubious wire rig far enough to test it.
*
* Unsupported as yet
*
* Time stamping of data from ring. Various ideas on how to do this but none
* are remotely simple. Suggestions welcome.
*
* Individual enabling disabling of channels going into ring buffer
*
* Overflow handling (this is signaled for all but 8 bit ring buffer mode.)
*
* Motion detector using AND combinations of signals.
*
* Note: Be very careful about not touching an register bytes marked
* as reserved on the data sheet. They really mean it as changing convents of
* some will cause the device to lock up.
*
* Known issues - on rare occasions the interrupts lock up. Not sure why as yet.
* Can probably alleviate this by reading the interrupt register on start, but
* that is really just brushing the problem under the carpet.
*/
#define SCA3000_WRITE_REG(a) (((a) << 2) | 0x02)
#define SCA3000_READ_REG(a) ((a) << 2)
#define SCA3000_REG_ADDR_REVID 0x00
#define SCA3000_REVID_MAJOR_MASK 0xf0
#define SCA3000_REVID_MINOR_MASK 0x0f
#define SCA3000_REG_ADDR_STATUS 0x02
#define SCA3000_LOCKED 0x20
#define SCA3000_EEPROM_CS_ERROR 0x02
#define SCA3000_SPI_FRAME_ERROR 0x01
/* All reads done using register decrement so no need to directly access LSBs */
#define SCA3000_REG_ADDR_X_MSB 0x05
#define SCA3000_REG_ADDR_Y_MSB 0x07
#define SCA3000_REG_ADDR_Z_MSB 0x09
#define SCA3000_REG_ADDR_RING_OUT 0x0f
/* Temp read untested - the e05 doesn't have the sensor */
#define SCA3000_REG_ADDR_TEMP_MSB 0x13
#define SCA3000_REG_ADDR_MODE 0x14
#define SCA3000_MODE_PROT_MASK 0x28
#define SCA3000_RING_BUF_ENABLE 0x80
#define SCA3000_RING_BUF_8BIT 0x40
/* Free fall detection triggers an interrupt if the acceleration
* is below a threshold for equivalent of 25cm drop
*/
#define SCA3000_FREE_FALL_DETECT 0x10
#define SCA3000_MEAS_MODE_NORMAL 0x00
#define SCA3000_MEAS_MODE_OP_1 0x01
#define SCA3000_MEAS_MODE_OP_2 0x02
/* In motion detection mode the accelerations are band pass filtered
* (aprox 1 - 25Hz) and then a programmable theshold used to trigger
* and interrupt.
*/
#define SCA3000_MEAS_MODE_MOT_DET 0x03
#define SCA3000_REG_ADDR_BUF_COUNT 0x15
#define SCA3000_REG_ADDR_INT_STATUS 0x16
#define SCA3000_INT_STATUS_THREE_QUARTERS 0x80
#define SCA3000_INT_STATUS_HALF 0x40
#define SCA3000_INT_STATUS_FREE_FALL 0x08
#define SCA3000_INT_STATUS_Y_TRIGGER 0x04
#define SCA3000_INT_STATUS_X_TRIGGER 0x02
#define SCA3000_INT_STATUS_Z_TRIGGER 0x01
/* Used to allow accesss to multiplexed registers */
#define SCA3000_REG_ADDR_CTRL_SEL 0x18
/* Only available for SCA3000-D03 and SCA3000-D01 */
#define SCA3000_REG_CTRL_SEL_I2C_DISABLE 0x01
#define SCA3000_REG_CTRL_SEL_MD_CTRL 0x02
#define SCA3000_REG_CTRL_SEL_MD_Y_TH 0x03
#define SCA3000_REG_CTRL_SEL_MD_X_TH 0x04
#define SCA3000_REG_CTRL_SEL_MD_Z_TH 0x05
/* BE VERY CAREFUL WITH THIS, IF 3 BITS ARE NOT SET the device
will not function */
#define SCA3000_REG_CTRL_SEL_OUT_CTRL 0x0B
#define SCA3000_OUT_CTRL_PROT_MASK 0xE0
#define SCA3000_OUT_CTRL_BUF_X_EN 0x10
#define SCA3000_OUT_CTRL_BUF_Y_EN 0x08
#define SCA3000_OUT_CTRL_BUF_Z_EN 0x04
#define SCA3000_OUT_CTRL_BUF_DIV_4 0x02
#define SCA3000_OUT_CTRL_BUF_DIV_2 0x01
/* Control which motion detector interrupts are on.
* For now only OR combinations are supported.x
*/
#define SCA3000_MD_CTRL_PROT_MASK 0xC0
#define SCA3000_MD_CTRL_OR_Y 0x01
#define SCA3000_MD_CTRL_OR_X 0x02
#define SCA3000_MD_CTRL_OR_Z 0x04
/* Currently unsupported */
#define SCA3000_MD_CTRL_AND_Y 0x08
#define SCA3000_MD_CTRL_AND_X 0x10
#define SAC3000_MD_CTRL_AND_Z 0x20
/* Some control registers of complex access methods requiring this register to
* be used to remove a lock.
*/
#define SCA3000_REG_ADDR_UNLOCK 0x1e
#define SCA3000_REG_ADDR_INT_MASK 0x21
#define SCA3000_INT_MASK_PROT_MASK 0x1C
#define SCA3000_INT_MASK_RING_THREE_QUARTER 0x80
#define SCA3000_INT_MASK_RING_HALF 0x40
#define SCA3000_INT_MASK_ALL_INTS 0x02
#define SCA3000_INT_MASK_ACTIVE_HIGH 0x01
#define SCA3000_INT_MASK_ACTIVE_LOW 0x00
/* Values of mulipexed registers (write to ctrl_data after select) */
#define SCA3000_REG_ADDR_CTRL_DATA 0x22
/* Measurment modes available on some sca3000 series chips. Code assumes others
* may become available in the future.
*
* Bypass - Bypass the low-pass filter in the signal channel so as to increase
* signal bandwidth.
*
* Narrow - Narrow low-pass filtering of the signal channel and half output
* data rate by decimation.
*
* Wide - Widen low-pass filtering of signal channel to increase bandwidth
*/
#define SCA3000_OP_MODE_BYPASS 0x01
#define SCA3000_OP_MODE_NARROW 0x02
#define SCA3000_OP_MODE_WIDE 0x04
#define SCA3000_MAX_TX 6
#define SCA3000_MAX_RX 2
/**
* struct sca3000_state - device instance state information
* @us: the associated spi device
* @info: chip variant information
* @indio_dev: device information used by the IIO core
* @interrupt_handler_ws: event interrupt handler for all events
* @last_timestamp: the timestamp of the last event
* @mo_det_use_count: reference counter for the motion detection unit
* @lock: lock used to protect elements of sca3000_state
* and the underlying device state.
* @bpse: number of bits per scan element
* @tx: dma-able transmit buffer
* @rx: dma-able receive buffer
**/
struct sca3000_state {
struct spi_device *us;
const struct sca3000_chip_info *info;
struct iio_dev *indio_dev;
struct work_struct interrupt_handler_ws;
s64 last_timestamp;
int mo_det_use_count;
struct mutex lock;
int bpse;
u8 *tx;
/* not used during a ring buffer read */
u8 *rx;
};
/**
* struct sca3000_chip_info - model dependant parameters
* @name: model identification
* @temp_output: some devices have temperature sensors.
* @measurement_mode_freq: normal mode sampling frequency
* @option_mode_1: first optional mode. Not all models have one
* @option_mode_1_freq: option mode 1 sampling frequency
* @option_mode_2: second optional mode. Not all chips have one
* @option_mode_2_freq: option mode 2 sampling frequency
*
* This structure is used to hold information about the functionality of a given
* sca3000 variant.
**/
struct sca3000_chip_info {
const char *name;
bool temp_output;
int measurement_mode_freq;
int option_mode_1;
int option_mode_1_freq;
int option_mode_2;
int option_mode_2_freq;
};
/**
* sca3000_read_data() read a series of values from the device
* @dev: device
* @reg_address_high: start address (decremented read)
* @rx: pointer where recieved data is placed. Callee
* responsible for freeing this.
* @len: number of bytes to read
*
* The main lock must be held.
**/
int sca3000_read_data(struct sca3000_state *st,
u8 reg_address_high,
u8 **rx_p,
int len);
/**
* sca3000_write_reg() write a single register
* @address: address of register on chip
* @val: value to be written to register
*
* The main lock must be held.
**/
int sca3000_write_reg(struct sca3000_state *st, u8 address, u8 val);
/* Conversion function for use with the ring buffer when in 11bit mode */
static inline int sca3000_11bit_convert(uint8_t msb, uint8_t lsb)
{
int16_t val;
val = ((lsb >> 3) & 0x1C) | (msb << 5);
val |= (val & (1 << 12)) ? 0xE000 : 0;
return val;
};
static inline int sca3000_13bit_convert(uint8_t msb, uint8_t lsb)
{
s16 val;
val = ((lsb >> 3) & 0x1F) | (msb << 5);
/* sign fill */
val |= (val & (1 << 12)) ? 0xE000 : 0;
return val;
};
#ifdef CONFIG_IIO_RING_BUFFER
/**
* sca3000_register_ring_funcs() setup the ring state change functions
**/
void sca3000_register_ring_funcs(struct iio_dev *indio_dev);
/**
* sca3000_configure_ring() - allocate and configure ring buffer
* @indio_dev: iio-core device whose ring is to be configured
*
* The hardware ring buffer needs far fewer ring buffer functions than
* a software one as a lot of things are handled automatically.
* This function also tells the iio core that our device supports a
* hardware ring buffer mode.
**/
int sca3000_configure_ring(struct iio_dev *indio_dev);
/**
* sca3000_unconfigure_ring() - deallocate the ring buffer
* @indio_dev: iio-core device whose ring we are freeing
**/
void sca3000_unconfigure_ring(struct iio_dev *indio_dev);
/**
* sca3000_ring_int_process() handles ring related event pushing and escalation
* @val: the event code
**/
void sca3000_ring_int_process(u8 val, struct iio_ring_buffer *ring);
#else
static inline void sca3000_register_ring_funcs(struct iio_dev *indio_dev) {};
static inline
int sca3000_register_ring_access_and_init(struct iio_dev *indio_dev)
{
return 0;
};
static inline void sca3000_ring_int_process(u8 val, void *ring) {};
#endif

1509
drivers/staging/iio/accel/sca3000_core.c Normal file
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File diff suppressed because it is too large Load Diff

331
drivers/staging/iio/accel/sca3000_ring.c Normal file
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@ -0,0 +1,331 @@
/*
* sca3000_ring.c -- support VTI sca3000 series accelerometers via SPI
*
* 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.
*
* Copyright (c) 2009 Jonathan Cameron <jic23@cam.ac.uk>
*
*/
#include <linux/interrupt.h>
#include <linux/gpio.h>
#include <linux/fs.h>
#include <linux/device.h>
#include <linux/kernel.h>
#include <linux/spi/spi.h>
#include <linux/sysfs.h>
#include "../iio.h"
#include "../sysfs.h"
#include "../ring_generic.h"
#include "../ring_hw.h"
#include "accel.h"
#include "sca3000.h"
/* RFC / future work
*
* The internal ring buffer doesn't actually change what it holds depending
* on which signals are enabled etc, merely whether you can read them.
* As such the scan mode selection is somewhat different than for a software
* ring buffer and changing it actually covers any data already in the buffer.
* Currently scan elements aren't configured so it doesn't matter.
*/
/**
* sca3000_rip_hw_rb() - main ring access function, pulls data from ring
* @r: the ring
* @count: number of samples to try and pull
* @data: output the actual samples pulled from the hw ring
* @dead_offset: cheating a bit here: Set to 1 so as to allow for the
* leading byte used in bus comms.
*
* Currently does not provide timestamps. As the hardware doesn't add them they
* can only be inferred aproximately from ring buffer events such as 50% full
* and knowledge of when buffer was last emptied. This is left to userspace.
**/
static int sca3000_rip_hw_rb(struct iio_ring_buffer *r,
size_t count, u8 **data, int *dead_offset)
{
struct iio_hw_ring_buffer *hw_ring = iio_to_hw_ring_buf(r);
struct iio_dev *indio_dev = hw_ring->private;
struct sca3000_state *st = indio_dev->dev_data;
u8 *rx;
int ret, num_available, num_read = 0;
int bytes_per_sample = 1;
if (st->bpse == 11)
bytes_per_sample = 2;
mutex_lock(&st->lock);
/* Check how much data is available:
* RFC: Implement an ioctl to not bother checking whether there
* is enough data in the ring? Afterall, if we are responding
* to an interrupt we have a minimum content guaranteed so it
* seems slight silly to waste time checking it is there.
*/
ret = sca3000_read_data(st,
SCA3000_REG_ADDR_BUF_COUNT,
&rx, 1);
if (ret)
goto error_ret;
else
num_available = rx[1];
/* num_available is the total number of samples available
* i.e. number of time points * number of channels.
*/
kfree(rx);
if (count > num_available * bytes_per_sample)
num_read = num_available*bytes_per_sample;
else
num_read = count - (count % (bytes_per_sample));
/* Avoid the read request byte */
*dead_offset = 1;
ret = sca3000_read_data(st,
SCA3000_REG_ADDR_RING_OUT,
data, num_read);
error_ret:
mutex_unlock(&st->lock);
return ret ? ret : num_read;
}
/* This is only valid with all 3 elements enabled */
static int sca3000_ring_get_length(struct iio_ring_buffer *r)
{
return 64;
}
/* only valid if resolution is kept at 11bits */
static int sca3000_ring_get_bpd(struct iio_ring_buffer *r)
{
return 6;
}
static void sca3000_ring_release(struct device *dev)
{
struct iio_ring_buffer *r = to_iio_ring_buffer(dev);
kfree(iio_to_hw_ring_buf(r));
}
static IIO_RING_ENABLE_ATTR;
static IIO_RING_BPS_ATTR;
static IIO_RING_LENGTH_ATTR;
/**
* sca3000_show_ring_bpse() -sysfs function to query bits per sample from ring
* @dev: ring buffer device
* @attr: this device attribute
* @buf: buffer to write to
**/
static ssize_t sca3000_show_ring_bpse(struct device *dev,
struct device_attribute *attr,
char *buf)
{
int len = 0, ret;
u8 *rx;
struct iio_ring_buffer *r = dev_get_drvdata(dev);
struct sca3000_state *st = r->indio_dev->dev_data;
mutex_lock(&st->lock);
ret = sca3000_read_data(st, SCA3000_REG_ADDR_MODE, &rx, 1);
if (ret)
goto error_ret;
len = sprintf(buf, "%d\n", (rx[1] & SCA3000_RING_BUF_8BIT) ? 8 : 11);
kfree(rx);
error_ret:
mutex_unlock(&st->lock);
return ret ? ret : len;
}
/**
* sca3000_store_ring_bpse() - bits per scan element
* @dev: ring buffer device
* @attr: attribute called from
* @buf: input from userspace
* @len: length of input
**/
static ssize_t sca3000_store_ring_bpse(struct device *dev,
struct device_attribute *attr,
const char *buf,
size_t len)
{
struct iio_ring_buffer *r = dev_get_drvdata(dev);
struct sca3000_state *st = r->indio_dev->dev_data;
int ret;
u8 *rx;
long val;
ret = strict_strtol(buf, 10, &val);
if (ret)
return ret;
mutex_lock(&st->lock);
ret = sca3000_read_data(st, SCA3000_REG_ADDR_MODE, &rx, 1);
if (!ret)
switch (val) {
case 8:
ret = sca3000_write_reg(st, SCA3000_REG_ADDR_MODE,
rx[1] | SCA3000_RING_BUF_8BIT);
st->bpse = 8;
break;
case 11:
ret = sca3000_write_reg(st, SCA3000_REG_ADDR_MODE,
rx[1] & ~SCA3000_RING_BUF_8BIT);
st->bpse = 11;
break;
default:
ret = -EINVAL;
break;
}
mutex_unlock(&st->lock);
return ret ? ret : len;
}
static IIO_CONST_ATTR(bpse_available, "8 11");
static IIO_DEV_ATTR_BPSE(S_IRUGO | S_IWUSR,
sca3000_show_ring_bpse,
sca3000_store_ring_bpse);
/*
* Ring buffer attributes
* This device is a bit unusual in that the sampling frequency and bpse
* only apply to the ring buffer. At all times full rate and accuracy
* is available via direct reading from registers.
*/
static struct attribute *iio_ring_attributes[] = {
&dev_attr_length.attr,
&dev_attr_bps.attr,
&dev_attr_ring_enable.attr,
&iio_dev_attr_bpse.dev_attr.attr,
&iio_const_attr_bpse_available.dev_attr.attr,
NULL,
};
static struct attribute_group sca3000_ring_attr = {
.attrs = iio_ring_attributes,
};
static struct attribute_group *sca3000_ring_attr_groups[] = {
&sca3000_ring_attr,
NULL
};
static struct device_type sca3000_ring_type = {
.release = sca3000_ring_release,
.groups = sca3000_ring_attr_groups,
};
static struct iio_ring_buffer *sca3000_rb_allocate(struct iio_dev *indio_dev)
{
struct iio_ring_buffer *buf;
struct iio_hw_ring_buffer *ring;
ring = kzalloc(sizeof *ring, GFP_KERNEL);
if (!ring)
return 0;
ring->private = indio_dev;
buf = &ring->buf;
iio_ring_buffer_init(buf, indio_dev);
buf->dev.type = &sca3000_ring_type;
device_initialize(&buf->dev);
buf->dev.parent = &indio_dev->dev;
dev_set_drvdata(&buf->dev, (void *)buf);
return buf;
}
static inline void sca3000_rb_free(struct iio_ring_buffer *r)
{
if (r)
iio_put_ring_buffer(r);
}
int sca3000_configure_ring(struct iio_dev *indio_dev)
{
indio_dev->ring = sca3000_rb_allocate(indio_dev);
if (indio_dev->ring == NULL)
return -ENOMEM;
indio_dev->modes |= INDIO_RING_HARDWARE_BUFFER;
indio_dev->ring->access.rip_lots = &sca3000_rip_hw_rb;
indio_dev->ring->access.get_length = &sca3000_ring_get_length;
indio_dev->ring->access.get_bpd = &sca3000_ring_get_bpd;
return 0;
}
void sca3000_unconfigure_ring(struct iio_dev *indio_dev)
{
sca3000_rb_free(indio_dev->ring);
}
static inline
int __sca3000_hw_ring_state_set(struct iio_dev *indio_dev, bool state)
{
struct sca3000_state *st = indio_dev->dev_data;
int ret;
u8 *rx;
mutex_lock(&st->lock);
ret = sca3000_read_data(st, SCA3000_REG_ADDR_MODE, &rx, 1);
if (ret)
goto error_ret;
if (state) {
printk(KERN_INFO "supposedly enabling ring buffer\n");
ret = sca3000_write_reg(st,
SCA3000_REG_ADDR_MODE,
(rx[1] | SCA3000_RING_BUF_ENABLE));
} else
ret = sca3000_write_reg(st,
SCA3000_REG_ADDR_MODE,
(rx[1] & ~SCA3000_RING_BUF_ENABLE));
kfree(rx);
error_ret:
mutex_unlock(&st->lock);
return ret;
}
/**
* sca3000_hw_ring_preenable() hw ring buffer preenable function
*
* Very simple enable function as the chip will allows normal reads
* during ring buffer operation so as long as it is indeed running
* before we notify the core, the precise ordering does not matter.
**/
static int sca3000_hw_ring_preenable(struct iio_dev *indio_dev)
{
return __sca3000_hw_ring_state_set(indio_dev, 1);
}
static int sca3000_hw_ring_postdisable(struct iio_dev *indio_dev)
{
return __sca3000_hw_ring_state_set(indio_dev, 0);
}
void sca3000_register_ring_funcs(struct iio_dev *indio_dev)
{
indio_dev->ring->preenable = &sca3000_hw_ring_preenable;
indio_dev->ring->postdisable = &sca3000_hw_ring_postdisable;
}
/**
* sca3000_ring_int_process() ring specific interrupt handling.
*
* This is only split from the main interrupt handler so as to
* reduce the amount of code if the ring buffer is not enabled.
**/
void sca3000_ring_int_process(u8 val, struct iio_ring_buffer *ring)
{
if (val & SCA3000_INT_STATUS_THREE_QUARTERS)
iio_push_or_escallate_ring_event(ring,
IIO_EVENT_CODE_RING_75_FULL,
0);
else if (val & SCA3000_INT_STATUS_HALF)
iio_push_ring_event(ring,
IIO_EVENT_CODE_RING_50_FULL, 0);
}

22
drivers/staging/iio/ring_hw.h Normal file
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/*
* ring_hw.h - common functionality for iio hardware ring buffers
*
* 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.
*
* Copyright (c) 2009 Jonathan Cameron <jic23@cam.ac.uk>
*
*/
/**
* struct iio_hw_ring_buffer- hardware ring buffer
* @buf: generic ring buffer elements
* @private: device specific data
*/
struct iio_hw_ring_buffer {
struct iio_ring_buffer buf;
void *private;
};
#define iio_to_hw_ring_buf(r) container_of(r, struct iio_hw_ring_buffer, buf)