drivers/staging/iio/accel/sca3000_ring.c

   1 /*
   2  * sca3000_ring.c -- support VTI sca3000 series accelerometers via SPI
   3  *
   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.
   7  *
   8  * Copyright (c) 2009 Jonathan Cameron <jic23@kernel.org>
   9  *
  10  */
  11
  12 #include <linux/interrupt.h>
  13 #include <linux/fs.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>
  20
  21 #include <linux/iio/iio.h>
  22 #include <linux/iio/sysfs.h>
  23 #include <linux/iio/buffer.h>
  24 #include "../ring_hw.h"
  25 #include "sca3000.h"
  26
  27 /* RFC / future work
  28  *
  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.
  34  */
  35
  36 static int sca3000_read_data(struct sca3000_state *st,
  37                             uint8_t reg_address_high,
  38                             u8 **rx_p,
  39                             int len)
  40 {
  41         int ret;
  42         struct spi_transfer xfer[2] = {
  43                 {
  44                         .len = 1,
  45                         .tx_buf = st->tx,
  46                 }, {
  47                         .len = len,
  48                 }
  49         };
  50         *rx_p = kmalloc(len, GFP_KERNEL);
  51         if (*rx_p == NULL) {
  52                 ret = -ENOMEM;
  53                 goto error_ret;
  54         }
  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));
  58         if (ret) {
  59                 dev_err(get_device(&st->us->dev), "problem reading register");
  60                 goto error_free_rx;
  61         }
  62
  63         return 0;
  64 error_free_rx:
  65         kfree(*rx_p);
  66 error_ret:
  67         return ret;
  68 }
  69
  70 /**
  71  * sca3000_read_first_n_hw_rb() - main ring access, pulls data from ring
  72  * @r:                  the ring
  73  * @count:              number of samples to try and pull
  74  * @data:               output the actual samples pulled from the hw ring
  75  *
  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.
  79  **/
  80 static int sca3000_read_first_n_hw_rb(struct iio_buffer *r,
  81                                       size_t count, char __user *buf)
  82 {
  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);
  86         u8 *rx;
  87         int ret, i, num_available, num_read = 0;
  88         int bytes_per_sample = 1;
  89
  90         if (st->bpse == 11)
  91                 bytes_per_sample = 2;
  92
  93         mutex_lock(&st->lock);
  94         if (count % bytes_per_sample) {
  95                 ret = -EINVAL;
  96                 goto error_ret;
  97         }
  98
  99         ret = sca3000_read_data_short(st, SCA3000_REG_ADDR_BUF_COUNT, 1);
 100         if (ret)
 101                 goto error_ret;
 102         else
 103                 num_available = st->rx[0];
 104         /*
 105          * num_available is the total number of samples available
 106          * i.e. number of time points * number of channels.
 107          */
 108         if (count > num_available * bytes_per_sample)
 109                 num_read = num_available*bytes_per_sample;
 110         else
 111                 num_read = count;
 112
 113         ret = sca3000_read_data(st,
 114                                 SCA3000_REG_ADDR_RING_OUT,
 115                                 &rx, num_read);
 116         if (ret)
 117                 goto error_ret;
 118
 119         for (i = 0; i < num_read; i++)
 120                 *(((u16 *)rx) + i) = be16_to_cpup((__be16 *)rx + i);
 121
 122         if (copy_to_user(buf, rx, num_read))
 123                 ret = -EFAULT;
 124         kfree(rx);
 125         r->stufftoread = 0;
 126 error_ret:
 127         mutex_unlock(&st->lock);
 128
 129         return ret ? ret : num_read;
 130 }
 131
 132 static size_t sca3000_ring_buf_data_available(struct iio_buffer *r)
 133 {
 134         return r->stufftoread ? r->watermark : 0;
 135 }
 136
 137 /**
 138  * sca3000_query_ring_int() is the hardware ring status interrupt enabled
 139  **/
 140 static ssize_t sca3000_query_ring_int(struct device *dev,
 141                                       struct device_attribute *attr,
 142                                       char *buf)
 143 {
 144         struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
 145         int ret, val;
 146         struct iio_dev *indio_dev = dev_to_iio_dev(dev);
 147         struct sca3000_state *st = iio_priv(indio_dev);
 148
 149         mutex_lock(&st->lock);
 150         ret = sca3000_read_data_short(st, SCA3000_REG_ADDR_INT_MASK, 1);
 151         val = st->rx[0];
 152         mutex_unlock(&st->lock);
 153         if (ret)
 154                 return ret;
 155
 156         return sprintf(buf, "%d\n", !!(val & this_attr->address));
 157 }
 158
 159 /**
 160  * sca3000_set_ring_int() set state of ring status interrupt
 161  **/
 162 static ssize_t sca3000_set_ring_int(struct device *dev,
 163                                       struct device_attribute *attr,
 164                                       const char *buf,
 165                                       size_t len)
 166 {
 167         struct iio_dev *indio_dev = dev_to_iio_dev(dev);
 168         struct sca3000_state *st = iio_priv(indio_dev);
 169         struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
 170         u8 val;
 171         int ret;
 172
 173         mutex_lock(&st->lock);
 174         ret = kstrtou8(buf, 10, &val);
 175         if (ret)
 176                 goto error_ret;
 177         ret = sca3000_read_data_short(st, SCA3000_REG_ADDR_INT_MASK, 1);
 178         if (ret)
 179                 goto error_ret;
 180         if (val)
 181                 ret = sca3000_write_reg(st,
 182                                         SCA3000_REG_ADDR_INT_MASK,
 183                                         st->rx[0] | this_attr->address);
 184         else
 185                 ret = sca3000_write_reg(st,
 186                                         SCA3000_REG_ADDR_INT_MASK,
 187                                         st->rx[0] & ~this_attr->address);
 188 error_ret:
 189         mutex_unlock(&st->lock);
 190
 191         return ret ? ret : len;
 192 }
 193
 194 static IIO_DEVICE_ATTR(50_percent, S_IRUGO | S_IWUSR,
 195                        sca3000_query_ring_int,
 196                        sca3000_set_ring_int,
 197                        SCA3000_INT_MASK_RING_HALF);
 198
 199 static IIO_DEVICE_ATTR(75_percent, S_IRUGO | S_IWUSR,
 200                        sca3000_query_ring_int,
 201                        sca3000_set_ring_int,
 202                        SCA3000_INT_MASK_RING_THREE_QUARTER);
 203
 204 static ssize_t sca3000_show_buffer_scale(struct device *dev,
 205                                          struct device_attribute *attr,
 206                                          char *buf)
 207 {
 208         struct iio_dev *indio_dev = dev_to_iio_dev(dev);
 209         struct sca3000_state *st = iio_priv(indio_dev);
 210
 211         return sprintf(buf, "0.%06d\n", 4*st->info->scale);
 212 }
 213
 214 static IIO_DEVICE_ATTR(in_accel_scale,
 215                        S_IRUGO,
 216                        sca3000_show_buffer_scale,
 217                        NULL,
 218                        0);
 219
 220 /*
 221  * Ring buffer attributes
 222  * This device is a bit unusual in that the sampling frequency and bpse
 223  * only apply to the ring buffer.  At all times full rate and accuracy
 224  * is available via direct reading from registers.
 225  */
 226 static const struct attribute *sca3000_ring_attributes[] = {
 227         &iio_dev_attr_50_percent.dev_attr.attr,
 228         &iio_dev_attr_75_percent.dev_attr.attr,
 229         &iio_dev_attr_in_accel_scale.dev_attr.attr,
 230         NULL,
 231 };
 232
 233 static struct iio_buffer *sca3000_rb_allocate(struct iio_dev *indio_dev)
 234 {
 235         struct iio_buffer *buf;
 236         struct iio_hw_buffer *ring;
 237
 238         ring = kzalloc(sizeof(*ring), GFP_KERNEL);
 239         if (!ring)
 240                 return NULL;
 241
 242         ring->private = indio_dev;
 243         buf = &ring->buf;
 244         buf->stufftoread = 0;
 245         buf->length = 64;
 246         buf->attrs = sca3000_ring_attributes;
 247         iio_buffer_init(buf);
 248
 249         return buf;
 250 }
 251
 252 static void sca3000_ring_release(struct iio_buffer *r)
 253 {
 254         kfree(iio_to_hw_buf(r));
 255 }
 256
 257 static const struct iio_buffer_access_funcs sca3000_ring_access_funcs = {
 258         .read_first_n = &sca3000_read_first_n_hw_rb,
 259         .data_available = sca3000_ring_buf_data_available,
 260         .release = sca3000_ring_release,
 261
 262         .modes = INDIO_BUFFER_HARDWARE,
 263 };
 264
 265 int sca3000_configure_ring(struct iio_dev *indio_dev)
 266 {
 267         struct iio_buffer *buffer;
 268
 269         buffer = sca3000_rb_allocate(indio_dev);
 270         if (buffer == NULL)
 271                 return -ENOMEM;
 272         indio_dev->modes |= INDIO_BUFFER_HARDWARE;
 273
 274         indio_dev->buffer->access = &sca3000_ring_access_funcs;
 275
 276         iio_device_attach_buffer(indio_dev, buffer);
 277
 278         return 0;
 279 }
 280
 281 void sca3000_unconfigure_ring(struct iio_dev *indio_dev)
 282 {
 283         iio_buffer_put(indio_dev->buffer);
 284 }
 285
 286 static inline
 287 int __sca3000_hw_ring_state_set(struct iio_dev *indio_dev, bool state)
 288 {
 289         struct sca3000_state *st = iio_priv(indio_dev);
 290         int ret;
 291
 292         mutex_lock(&st->lock);
 293         ret = sca3000_read_data_short(st, SCA3000_REG_ADDR_MODE, 1);
 294         if (ret)
 295                 goto error_ret;
 296         if (state) {
 297                 dev_info(&indio_dev->dev, "supposedly enabling ring buffer\n");
 298                 ret = sca3000_write_reg(st,
 299                                         SCA3000_REG_ADDR_MODE,
 300                                         (st->rx[0] | SCA3000_RING_BUF_ENABLE));
 301         } else
 302                 ret = sca3000_write_reg(st,
 303                                         SCA3000_REG_ADDR_MODE,
 304                                         (st->rx[0] & ~SCA3000_RING_BUF_ENABLE));
 305 error_ret:
 306         mutex_unlock(&st->lock);
 307
 308         return ret;
 309 }
 310 /**
 311  * sca3000_hw_ring_preenable() hw ring buffer preenable function
 312  *
 313  * Very simple enable function as the chip will allows normal reads
 314  * during ring buffer operation so as long as it is indeed running
 315  * before we notify the core, the precise ordering does not matter.
 316  **/
 317 static int sca3000_hw_ring_preenable(struct iio_dev *indio_dev)
 318 {
 319         return __sca3000_hw_ring_state_set(indio_dev, 1);
 320 }
 321
 322 static int sca3000_hw_ring_postdisable(struct iio_dev *indio_dev)
 323 {
 324         return __sca3000_hw_ring_state_set(indio_dev, 0);
 325 }
 326
 327 static const struct iio_buffer_setup_ops sca3000_ring_setup_ops = {
 328         .preenable = &sca3000_hw_ring_preenable,
 329         .postdisable = &sca3000_hw_ring_postdisable,
 330 };
 331
 332 void sca3000_register_ring_funcs(struct iio_dev *indio_dev)
 333 {
 334         indio_dev->setup_ops = &sca3000_ring_setup_ops;
 335 }
 336
 337 /**
 338  * sca3000_ring_int_process() ring specific interrupt handling.
 339  *
 340  * This is only split from the main interrupt handler so as to
 341  * reduce the amount of code if the ring buffer is not enabled.
 342  **/
 343 void sca3000_ring_int_process(u8 val, struct iio_buffer *ring)
 344 {
 345         if (val & (SCA3000_INT_STATUS_THREE_QUARTERS |
 346                    SCA3000_INT_STATUS_HALF)) {
 347                 ring->stufftoread = true;
 348                 wake_up_interruptible(&ring->pollq);
 349         }
 350 }