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@cam.ac.uk>
   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 "../iio.h"
  22 #include "../sysfs.h"
  23 #include "../ring_generic.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_message msg;
  43         struct spi_transfer xfer[2] = {
  44                 {
  45                         .len = 1,
  46                         .tx_buf = st->tx,
  47                 }, {
  48                         .len = len,
  49                 }
  50         };
  51         *rx_p = kmalloc(len, GFP_KERNEL);
  52         if (*rx_p == NULL) {
  53                 ret = -ENOMEM;
  54                 goto error_ret;
  55         }
  56         xfer[1].rx_buf = *rx_p;
  57         st->tx[0] = SCA3000_READ_REG(reg_address_high);
  58         spi_message_init(&msg);
  59         spi_message_add_tail(&xfer[0], &msg);
  60         spi_message_add_tail(&xfer[1], &msg);
  61         ret = spi_sync(st->us, &msg);
  62         if (ret) {
  63                 dev_err(get_device(&st->us->dev), "problem reading register");
  64                 goto error_free_rx;
  65         }
  66
  67         return 0;
  68 error_free_rx:
  69         kfree(*rx_p);
  70 error_ret:
  71         return ret;
  72 }
  73
  74 /**
  75  * sca3000_read_first_n_hw_rb() - main ring access, pulls data from ring
  76  * @r:                  the ring
  77  * @count:              number of samples to try and pull
  78  * @data:               output the actual samples pulled from the hw ring
  79  *
  80  * Currently does not provide timestamps.  As the hardware doesn't add them they
  81  * can only be inferred approximately from ring buffer events such as 50% full
  82  * and knowledge of when buffer was last emptied.  This is left to userspace.
  83  **/
  84 static int sca3000_read_first_n_hw_rb(struct iio_ring_buffer *r,
  85                                       size_t count, char __user *buf)
  86 {
  87         struct iio_hw_ring_buffer *hw_ring = iio_to_hw_ring_buf(r);
  88         struct iio_dev *indio_dev = hw_ring->private;
  89         struct sca3000_state *st = iio_priv(indio_dev);
  90         u8 *rx;
  91         int ret, i, num_available, num_read = 0;
  92         int bytes_per_sample = 1;
  93
  94         if (st->bpse == 11)
  95                 bytes_per_sample = 2;
  96
  97         mutex_lock(&st->lock);
  98         if (count % bytes_per_sample) {
  99                 ret = -EINVAL;
 100                 goto error_ret;
 101         }
 102
 103         ret = sca3000_read_data_short(st, SCA3000_REG_ADDR_BUF_COUNT, 1);
 104         if (ret)
 105                 goto error_ret;
 106         else
 107                 num_available = st->rx[0];
 108         /*
 109          * num_available is the total number of samples available
 110          * i.e. number of time points * number of channels.
 111          */
 112         if (count > num_available * bytes_per_sample)
 113                 num_read = num_available*bytes_per_sample;
 114         else
 115                 num_read = count;
 116
 117         ret = sca3000_read_data(st,
 118                                 SCA3000_REG_ADDR_RING_OUT,
 119                                 &rx, num_read);
 120         if (ret)
 121                 goto error_ret;
 122
 123         for (i = 0; i < num_read; i++)
 124                 *(((u16 *)rx) + i) = be16_to_cpup((u16 *)rx + i);
 125
 126         if (copy_to_user(buf, rx, num_read))
 127                 ret = -EFAULT;
 128         kfree(rx);
 129         r->stufftoread = 0;
 130 error_ret:
 131         mutex_unlock(&st->lock);
 132
 133         return ret ? ret : num_read;
 134 }
 135
 136 /* This is only valid with all 3 elements enabled */
 137 static int sca3000_ring_get_length(struct iio_ring_buffer *r)
 138 {
 139         return 64;
 140 }
 141
 142 /* only valid if resolution is kept at 11bits */
 143 static int sca3000_ring_get_bytes_per_datum(struct iio_ring_buffer *r)
 144 {
 145         return 6;
 146 }
 147
 148 static IIO_RING_ENABLE_ATTR;
 149 static IIO_RING_BYTES_PER_DATUM_ATTR;
 150 static IIO_RING_LENGTH_ATTR;
 151
 152 /**
 153  * sca3000_query_ring_int() is the hardware ring status interrupt enabled
 154  **/
 155 static ssize_t sca3000_query_ring_int(struct device *dev,
 156                                       struct device_attribute *attr,
 157                                       char *buf)
 158 {
 159         struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
 160         int ret, val;
 161         struct iio_ring_buffer *ring = dev_get_drvdata(dev);
 162         struct iio_dev *indio_dev = ring->indio_dev;
 163         struct sca3000_state *st = iio_priv(indio_dev);
 164
 165         mutex_lock(&st->lock);
 166         ret = sca3000_read_data_short(st, SCA3000_REG_ADDR_INT_MASK, 1);
 167         val = st->rx[0];
 168         mutex_unlock(&st->lock);
 169         if (ret)
 170                 return ret;
 171
 172         return sprintf(buf, "%d\n", !!(val & this_attr->address));
 173 }
 174
 175 /**
 176  * sca3000_set_ring_int() set state of ring status interrupt
 177  **/
 178 static ssize_t sca3000_set_ring_int(struct device *dev,
 179                                       struct device_attribute *attr,
 180                                       const char *buf,
 181                                       size_t len)
 182 {
 183         struct iio_ring_buffer *ring = dev_get_drvdata(dev);
 184         struct iio_dev *indio_dev = ring->indio_dev;
 185         struct sca3000_state *st = iio_priv(indio_dev);
 186         struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
 187         long val;
 188         int ret;
 189
 190         mutex_lock(&st->lock);
 191         ret = strict_strtol(buf, 10, &val);
 192         if (ret)
 193                 goto error_ret;
 194         ret = sca3000_read_data_short(st, SCA3000_REG_ADDR_INT_MASK, 1);
 195         if (ret)
 196                 goto error_ret;
 197         if (val)
 198                 ret = sca3000_write_reg(st,
 199                                         SCA3000_REG_ADDR_INT_MASK,
 200                                         st->rx[0] | this_attr->address);
 201         else
 202                 ret = sca3000_write_reg(st,
 203                                         SCA3000_REG_ADDR_INT_MASK,
 204                                         st->rx[0] & ~this_attr->address);
 205 error_ret:
 206         mutex_unlock(&st->lock);
 207
 208         return ret ? ret : len;
 209 }
 210
 211 static IIO_DEVICE_ATTR(50_percent, S_IRUGO | S_IWUSR,
 212                        sca3000_query_ring_int,
 213                        sca3000_set_ring_int,
 214                        SCA3000_INT_MASK_RING_HALF);
 215
 216 static IIO_DEVICE_ATTR(75_percent, S_IRUGO | S_IWUSR,
 217                        sca3000_query_ring_int,
 218                        sca3000_set_ring_int,
 219                        SCA3000_INT_MASK_RING_THREE_QUARTER);
 220
 221 static ssize_t sca3000_show_buffer_scale(struct device *dev,
 222                                          struct device_attribute *attr,
 223                                          char *buf)
 224 {
 225         struct iio_ring_buffer *ring = dev_get_drvdata(dev);
 226         struct iio_dev *indio_dev = ring->indio_dev;
 227         struct sca3000_state *st = iio_priv(indio_dev);
 228
 229         return sprintf(buf, "0.%06d\n", 4*st->info->scale);
 230 }
 231
 232 static IIO_DEVICE_ATTR(accel_scale,
 233                        S_IRUGO,
 234                        sca3000_show_buffer_scale,
 235                        NULL,
 236                        0);
 237
 238 /*
 239  * Ring buffer attributes
 240  * This device is a bit unusual in that the sampling frequency and bpse
 241  * only apply to the ring buffer.  At all times full rate and accuracy
 242  * is available via direct reading from registers.
 243  */
 244 static struct attribute *sca3000_ring_attributes[] = {
 245         &dev_attr_length.attr,
 246         &dev_attr_bytes_per_datum.attr,
 247         &dev_attr_enable.attr,
 248         &iio_dev_attr_50_percent.dev_attr.attr,
 249         &iio_dev_attr_75_percent.dev_attr.attr,
 250         &iio_dev_attr_accel_scale.dev_attr.attr,
 251         NULL,
 252 };
 253
 254 static struct attribute_group sca3000_ring_attr = {
 255         .attrs = sca3000_ring_attributes,
 256         .name = "buffer",
 257 };
 258
 259 static struct iio_ring_buffer *sca3000_rb_allocate(struct iio_dev *indio_dev)
 260 {
 261         struct iio_ring_buffer *buf;
 262         struct iio_hw_ring_buffer *ring;
 263
 264         ring = kzalloc(sizeof *ring, GFP_KERNEL);
 265         if (!ring)
 266                 return NULL;
 267
 268         ring->private = indio_dev;
 269         buf = &ring->buf;
 270         buf->stufftoread = 0;
 271         buf->attrs = &sca3000_ring_attr;
 272         iio_ring_buffer_init(buf, indio_dev);
 273
 274         return buf;
 275 }
 276
 277 static inline void sca3000_rb_free(struct iio_ring_buffer *r)
 278 {
 279         kfree(iio_to_hw_ring_buf(r));
 280 }
 281
 282 static const struct iio_ring_access_funcs sca3000_ring_access_funcs = {
 283         .read_first_n = &sca3000_read_first_n_hw_rb,
 284         .get_length = &sca3000_ring_get_length,
 285         .get_bytes_per_datum = &sca3000_ring_get_bytes_per_datum,
 286 };
 287
 288 int sca3000_configure_ring(struct iio_dev *indio_dev)
 289 {
 290         indio_dev->ring = sca3000_rb_allocate(indio_dev);
 291         if (indio_dev->ring == NULL)
 292                 return -ENOMEM;
 293         indio_dev->modes |= INDIO_RING_HARDWARE_BUFFER;
 294
 295         indio_dev->ring->access = &sca3000_ring_access_funcs;
 296
 297         iio_scan_mask_set(indio_dev->ring, 0);
 298         iio_scan_mask_set(indio_dev->ring, 1);
 299         iio_scan_mask_set(indio_dev->ring, 2);
 300
 301         return 0;
 302 }
 303
 304 void sca3000_unconfigure_ring(struct iio_dev *indio_dev)
 305 {
 306         sca3000_rb_free(indio_dev->ring);
 307 }
 308
 309 static inline
 310 int __sca3000_hw_ring_state_set(struct iio_dev *indio_dev, bool state)
 311 {
 312         struct sca3000_state *st = iio_priv(indio_dev);
 313         int ret;
 314
 315         mutex_lock(&st->lock);
 316         ret = sca3000_read_data_short(st, SCA3000_REG_ADDR_MODE, 1);
 317         if (ret)
 318                 goto error_ret;
 319         if (state) {
 320                 printk(KERN_INFO "supposedly enabling ring buffer\n");
 321                 ret = sca3000_write_reg(st,
 322                                         SCA3000_REG_ADDR_MODE,
 323                                         (st->rx[0] | SCA3000_RING_BUF_ENABLE));
 324         } else
 325                 ret = sca3000_write_reg(st,
 326                                         SCA3000_REG_ADDR_MODE,
 327                                         (st->rx[0] & ~SCA3000_RING_BUF_ENABLE));
 328 error_ret:
 329         mutex_unlock(&st->lock);
 330
 331         return ret;
 332 }
 333 /**
 334  * sca3000_hw_ring_preenable() hw ring buffer preenable function
 335  *
 336  * Very simple enable function as the chip will allows normal reads
 337  * during ring buffer operation so as long as it is indeed running
 338  * before we notify the core, the precise ordering does not matter.
 339  **/
 340 static int sca3000_hw_ring_preenable(struct iio_dev *indio_dev)
 341 {
 342         return __sca3000_hw_ring_state_set(indio_dev, 1);
 343 }
 344
 345 static int sca3000_hw_ring_postdisable(struct iio_dev *indio_dev)
 346 {
 347         return __sca3000_hw_ring_state_set(indio_dev, 0);
 348 }
 349
 350 static const struct iio_ring_setup_ops sca3000_ring_setup_ops = {
 351         .preenable = &sca3000_hw_ring_preenable,
 352         .postdisable = &sca3000_hw_ring_postdisable,
 353 };
 354
 355 void sca3000_register_ring_funcs(struct iio_dev *indio_dev)
 356 {
 357         indio_dev->ring->setup_ops = &sca3000_ring_setup_ops;
 358 }
 359
 360 /**
 361  * sca3000_ring_int_process() ring specific interrupt handling.
 362  *
 363  * This is only split from the main interrupt handler so as to
 364  * reduce the amount of code if the ring buffer is not enabled.
 365  **/
 366 void sca3000_ring_int_process(u8 val, struct iio_ring_buffer *ring)
 367 {
 368         if (val & (SCA3000_INT_STATUS_THREE_QUARTERS |
 369                    SCA3000_INT_STATUS_HALF)) {
 370                 ring->stufftoread = true;
 371                 wake_up_interruptible(&ring->pollq);
 372         }
 373 }