2 * sca3000_ring.c -- support VTI sca3000 series accelerometers via SPI
4 * This program is free software; you can redistribute it and/or modify it
5 * under the terms of the GNU General Public License version 2 as published by
6 * the Free Software Foundation.
8 * Copyright (c) 2009 Jonathan Cameron <jic23@kernel.org>
12 #include <linux/interrupt.h>
14 #include <linux/slab.h>
15 #include <linux/kernel.h>
16 #include <linux/spi/spi.h>
17 #include <linux/sysfs.h>
18 #include <linux/sched.h>
19 #include <linux/poll.h>
21 #include <linux/iio/iio.h>
22 #include <linux/iio/sysfs.h>
23 #include <linux/iio/buffer.h>
24 #include "../ring_hw.h"
29 * The internal ring buffer doesn't actually change what it holds depending
30 * on which signals are enabled etc, merely whether you can read them.
31 * As such the scan mode selection is somewhat different than for a software
32 * ring buffer and changing it actually covers any data already in the buffer.
33 * Currently scan elements aren't configured so it doesn't matter.
36 static int sca3000_read_data(struct sca3000_state *st,
37 uint8_t reg_address_high,
42 struct spi_transfer xfer[2] = {
50 *rx_p = kmalloc(len, GFP_KERNEL);
55 xfer[1].rx_buf = *rx_p;
56 st->tx[0] = SCA3000_READ_REG(reg_address_high);
57 ret = spi_sync_transfer(st->us, xfer, ARRAY_SIZE(xfer));
59 dev_err(get_device(&st->us->dev), "problem reading register");
71 * sca3000_read_first_n_hw_rb() - main ring access, pulls data from ring
73 * @count: number of samples to try and pull
74 * @data: output the actual samples pulled from the hw ring
76 * Currently does not provide timestamps. As the hardware doesn't add them they
77 * can only be inferred approximately from ring buffer events such as 50% full
78 * and knowledge of when buffer was last emptied. This is left to userspace.
80 static int sca3000_read_first_n_hw_rb(struct iio_buffer *r,
81 size_t count, char __user *buf)
83 struct iio_hw_buffer *hw_ring = iio_to_hw_buf(r);
84 struct iio_dev *indio_dev = hw_ring->private;
85 struct sca3000_state *st = iio_priv(indio_dev);
87 int ret, i, num_available, num_read = 0;
88 int bytes_per_sample = 1;
93 mutex_lock(&st->lock);
94 if (count % bytes_per_sample) {
99 ret = sca3000_read_data_short(st, SCA3000_REG_ADDR_BUF_COUNT, 1);
103 num_available = st->rx[0];
105 * num_available is the total number of samples available
106 * i.e. number of time points * number of channels.
108 if (count > num_available * bytes_per_sample)
109 num_read = num_available*bytes_per_sample;
113 ret = sca3000_read_data(st,
114 SCA3000_REG_ADDR_RING_OUT,
119 for (i = 0; i < num_read; i++)
120 *(((u16 *)rx) + i) = be16_to_cpup((u16 *)rx + i);
122 if (copy_to_user(buf, rx, num_read))
127 mutex_unlock(&st->lock);
129 return ret ? ret : num_read;
132 /* This is only valid with all 3 elements enabled */
133 static int sca3000_ring_get_length(struct iio_buffer *r)
138 /* only valid if resolution is kept at 11bits */
139 static int sca3000_ring_get_bytes_per_datum(struct iio_buffer *r)
144 static IIO_BUFFER_ENABLE_ATTR;
145 static IIO_BUFFER_LENGTH_ATTR;
148 * sca3000_query_ring_int() is the hardware ring status interrupt enabled
150 static ssize_t sca3000_query_ring_int(struct device *dev,
151 struct device_attribute *attr,
154 struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
156 struct iio_dev *indio_dev = dev_to_iio_dev(dev);
157 struct sca3000_state *st = iio_priv(indio_dev);
159 mutex_lock(&st->lock);
160 ret = sca3000_read_data_short(st, SCA3000_REG_ADDR_INT_MASK, 1);
162 mutex_unlock(&st->lock);
166 return sprintf(buf, "%d\n", !!(val & this_attr->address));
170 * sca3000_set_ring_int() set state of ring status interrupt
172 static ssize_t sca3000_set_ring_int(struct device *dev,
173 struct device_attribute *attr,
177 struct iio_dev *indio_dev = dev_to_iio_dev(dev);
178 struct sca3000_state *st = iio_priv(indio_dev);
179 struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
183 mutex_lock(&st->lock);
184 ret = strict_strtol(buf, 10, &val);
187 ret = sca3000_read_data_short(st, SCA3000_REG_ADDR_INT_MASK, 1);
191 ret = sca3000_write_reg(st,
192 SCA3000_REG_ADDR_INT_MASK,
193 st->rx[0] | this_attr->address);
195 ret = sca3000_write_reg(st,
196 SCA3000_REG_ADDR_INT_MASK,
197 st->rx[0] & ~this_attr->address);
199 mutex_unlock(&st->lock);
201 return ret ? ret : len;
204 static IIO_DEVICE_ATTR(50_percent, S_IRUGO | S_IWUSR,
205 sca3000_query_ring_int,
206 sca3000_set_ring_int,
207 SCA3000_INT_MASK_RING_HALF);
209 static IIO_DEVICE_ATTR(75_percent, S_IRUGO | S_IWUSR,
210 sca3000_query_ring_int,
211 sca3000_set_ring_int,
212 SCA3000_INT_MASK_RING_THREE_QUARTER);
214 static ssize_t sca3000_show_buffer_scale(struct device *dev,
215 struct device_attribute *attr,
218 struct iio_dev *indio_dev = dev_to_iio_dev(dev);
219 struct sca3000_state *st = iio_priv(indio_dev);
221 return sprintf(buf, "0.%06d\n", 4*st->info->scale);
224 static IIO_DEVICE_ATTR(in_accel_scale,
226 sca3000_show_buffer_scale,
231 * Ring buffer attributes
232 * This device is a bit unusual in that the sampling frequency and bpse
233 * only apply to the ring buffer. At all times full rate and accuracy
234 * is available via direct reading from registers.
236 static struct attribute *sca3000_ring_attributes[] = {
237 &dev_attr_length.attr,
238 &dev_attr_enable.attr,
239 &iio_dev_attr_50_percent.dev_attr.attr,
240 &iio_dev_attr_75_percent.dev_attr.attr,
241 &iio_dev_attr_in_accel_scale.dev_attr.attr,
245 static struct attribute_group sca3000_ring_attr = {
246 .attrs = sca3000_ring_attributes,
250 static struct iio_buffer *sca3000_rb_allocate(struct iio_dev *indio_dev)
252 struct iio_buffer *buf;
253 struct iio_hw_buffer *ring;
255 ring = kzalloc(sizeof *ring, GFP_KERNEL);
259 ring->private = indio_dev;
261 buf->stufftoread = 0;
262 buf->attrs = &sca3000_ring_attr;
263 iio_buffer_init(buf);
268 static inline void sca3000_rb_free(struct iio_buffer *r)
270 kfree(iio_to_hw_buf(r));
273 static const struct iio_buffer_access_funcs sca3000_ring_access_funcs = {
274 .read_first_n = &sca3000_read_first_n_hw_rb,
275 .get_length = &sca3000_ring_get_length,
276 .get_bytes_per_datum = &sca3000_ring_get_bytes_per_datum,
279 int sca3000_configure_ring(struct iio_dev *indio_dev)
281 indio_dev->buffer = sca3000_rb_allocate(indio_dev);
282 if (indio_dev->buffer == NULL)
284 indio_dev->modes |= INDIO_BUFFER_HARDWARE;
286 indio_dev->buffer->access = &sca3000_ring_access_funcs;
291 void sca3000_unconfigure_ring(struct iio_dev *indio_dev)
293 sca3000_rb_free(indio_dev->buffer);
297 int __sca3000_hw_ring_state_set(struct iio_dev *indio_dev, bool state)
299 struct sca3000_state *st = iio_priv(indio_dev);
302 mutex_lock(&st->lock);
303 ret = sca3000_read_data_short(st, SCA3000_REG_ADDR_MODE, 1);
307 printk(KERN_INFO "supposedly enabling ring buffer\n");
308 ret = sca3000_write_reg(st,
309 SCA3000_REG_ADDR_MODE,
310 (st->rx[0] | SCA3000_RING_BUF_ENABLE));
312 ret = sca3000_write_reg(st,
313 SCA3000_REG_ADDR_MODE,
314 (st->rx[0] & ~SCA3000_RING_BUF_ENABLE));
316 mutex_unlock(&st->lock);
321 * sca3000_hw_ring_preenable() hw ring buffer preenable function
323 * Very simple enable function as the chip will allows normal reads
324 * during ring buffer operation so as long as it is indeed running
325 * before we notify the core, the precise ordering does not matter.
327 static int sca3000_hw_ring_preenable(struct iio_dev *indio_dev)
329 return __sca3000_hw_ring_state_set(indio_dev, 1);
332 static int sca3000_hw_ring_postdisable(struct iio_dev *indio_dev)
334 return __sca3000_hw_ring_state_set(indio_dev, 0);
337 static const struct iio_buffer_setup_ops sca3000_ring_setup_ops = {
338 .preenable = &sca3000_hw_ring_preenable,
339 .postdisable = &sca3000_hw_ring_postdisable,
342 void sca3000_register_ring_funcs(struct iio_dev *indio_dev)
344 indio_dev->setup_ops = &sca3000_ring_setup_ops;
348 * sca3000_ring_int_process() ring specific interrupt handling.
350 * This is only split from the main interrupt handler so as to
351 * reduce the amount of code if the ring buffer is not enabled.
353 void sca3000_ring_int_process(u8 val, struct iio_buffer *ring)
355 if (val & (SCA3000_INT_STATUS_THREE_QUARTERS |
356 SCA3000_INT_STATUS_HALF)) {
357 ring->stufftoread = true;
358 wake_up_interruptible(&ring->pollq);