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/gpio.h>
  14 #include <linux/fs.h>
  15 #include <linux/device.h>
  16 #include <linux/slab.h>
  17 #include <linux/kernel.h>
  18 #include <linux/spi/spi.h>
  19 #include <linux/sysfs.h>
  20
  21 #include "../iio.h"
  22 #include "../sysfs.h"
  23 #include "../ring_generic.h"
  24 #include "../ring_hw.h"
  25 #include "accel.h"
  26 #include "sca3000.h"
  27
  28 /* RFC / future work
  29  *
  30  * The internal ring buffer doesn't actually change what it holds depending
  31  * on which signals are enabled etc, merely whether you can read them.
  32  * As such the scan mode selection is somewhat different than for a software
  33  * ring buffer and changing it actually covers any data already in the buffer.
  34  * Currently scan elements aren't configured so it doesn't matter.
  35  */
  36
  37 /**
  38  * sca3000_rip_hw_rb() - main ring access function, pulls data from ring
  39  * @r:                  the ring
  40  * @count:              number of samples to try and pull
  41  * @data:               output the actual samples pulled from the hw ring
  42  * @dead_offset:        cheating a bit here: Set to 1 so as to allow for the
  43  *                      leading byte used in bus comms.
  44  *
  45  * Currently does not provide timestamps.  As the hardware doesn't add them they
  46  * can only be inferred aproximately from ring buffer events such as 50% full
  47  * and knowledge of when buffer was last emptied.  This is left to userspace.
  48  **/
  49 static int sca3000_rip_hw_rb(struct iio_ring_buffer *r,
  50                              size_t count, u8 **data, int *dead_offset)
  51 {
  52         struct iio_hw_ring_buffer *hw_ring = iio_to_hw_ring_buf(r);
  53         struct iio_dev *indio_dev = hw_ring->private;
  54         struct sca3000_state *st = indio_dev->dev_data;
  55         u8 *rx;
  56         s16 *samples;
  57         int ret, i, num_available, num_read = 0;
  58         int bytes_per_sample = 1;
  59
  60         if (st->bpse == 11)
  61                 bytes_per_sample = 2;
  62
  63         mutex_lock(&st->lock);
  64         /* Check how much data is available:
  65          * RFC: Implement an ioctl to not bother checking whether there
  66          * is enough data in the ring?  Afterall, if we are responding
  67          * to an interrupt we have a minimum content guaranteed so it
  68          * seems slight silly to waste time checking it is there.
  69          */
  70         ret = sca3000_read_data(st,
  71                                 SCA3000_REG_ADDR_BUF_COUNT,
  72                                 &rx, 1);
  73         if (ret)
  74                 goto error_ret;
  75         else
  76                 num_available = rx[1];
  77         /* num_available is the total number of samples available
  78          * i.e. number of time points * number of channels.
  79          */
  80         kfree(rx);
  81         if (count > num_available * bytes_per_sample)
  82                 num_read = num_available*bytes_per_sample;
  83         else
  84                 num_read = count - (count % (bytes_per_sample));
  85
  86         /* Avoid the read request byte */
  87         *dead_offset = 1;
  88         ret = sca3000_read_data(st,
  89                                 SCA3000_REG_ADDR_RING_OUT,
  90                                 data, num_read);
  91
  92         /* Convert byte order and shift to default resolution */
  93         if (st->bpse == 11) {
  94                 samples = (s16*)(*data+1);
  95                 for (i = 0; i < (num_read/2); i++) {
  96                         samples[i] = be16_to_cpup(
  97                                         (__be16 *)&(samples[i]));
  98                         samples[i] >>= 3;
  99                 }
 100         }
 101
 102 error_ret:
 103         mutex_unlock(&st->lock);
 104
 105         return ret ? ret : num_read;
 106 }
 107
 108 /* This is only valid with all 3 elements enabled */
 109 static int sca3000_ring_get_length(struct iio_ring_buffer *r)
 110 {
 111         return 64;
 112 }
 113
 114 /* only valid if resolution is kept at 11bits */
 115 static int sca3000_ring_get_bytes_per_datum(struct iio_ring_buffer *r)
 116 {
 117         return 6;
 118 }
 119 static void sca3000_ring_release(struct device *dev)
 120 {
 121         struct iio_ring_buffer *r = to_iio_ring_buffer(dev);
 122         kfree(iio_to_hw_ring_buf(r));
 123 }
 124
 125 static IIO_RING_ENABLE_ATTR;
 126 static IIO_RING_BYTES_PER_DATUM_ATTR;
 127 static IIO_RING_LENGTH_ATTR;
 128
 129 /**
 130  * sca3000_show_ring_bpse() -sysfs function to query bits per sample from ring
 131  * @dev: ring buffer device
 132  * @attr: this device attribute
 133  * @buf: buffer to write to
 134  **/
 135 static ssize_t sca3000_show_ring_bpse(struct device *dev,
 136                                       struct device_attribute *attr,
 137                                       char *buf)
 138 {
 139         int len = 0, ret;
 140         u8 *rx;
 141         struct iio_dev *indio_dev = dev_get_drvdata(dev);
 142         struct sca3000_state *st = indio_dev->dev_data;
 143
 144         mutex_lock(&st->lock);
 145         ret = sca3000_read_data(st, SCA3000_REG_ADDR_MODE, &rx, 1);
 146         if (ret)
 147                 goto error_ret;
 148         if (rx[1] & SCA3000_RING_BUF_8BIT)
 149                 len = sprintf(buf, "s8/8\n");
 150         else
 151                 len = sprintf(buf, "s11/16\n");
 152         kfree(rx);
 153 error_ret:
 154         mutex_unlock(&st->lock);
 155
 156         return ret ? ret : len;
 157 }
 158
 159 /**
 160  * sca3000_store_ring_bpse() - bits per scan element
 161  * @dev: ring buffer device
 162  * @attr: attribute called from
 163  * @buf: input from userspace
 164  * @len: length of input
 165  **/
 166 static ssize_t sca3000_store_ring_bpse(struct device *dev,
 167                                       struct device_attribute *attr,
 168                                       const char *buf,
 169                                       size_t len)
 170 {
 171         struct iio_dev *indio_dev = dev_get_drvdata(dev);
 172         struct sca3000_state *st = indio_dev->dev_data;
 173         int ret;
 174         u8 *rx;
 175
 176         mutex_lock(&st->lock);
 177
 178         ret = sca3000_read_data(st, SCA3000_REG_ADDR_MODE, &rx, 1);
 179         if (ret)
 180                 goto error_ret;
 181         if (strncmp(buf, "s8/8", 4) == 0) {
 182                 ret = sca3000_write_reg(st, SCA3000_REG_ADDR_MODE,
 183                                         rx[1] | SCA3000_RING_BUF_8BIT);
 184                 st->bpse = 8;
 185         } else if (strncmp(buf, "s11/16", 5) == 0) {
 186                 ret = sca3000_write_reg(st, SCA3000_REG_ADDR_MODE,
 187                                         rx[1] & ~SCA3000_RING_BUF_8BIT);
 188                 st->bpse = 11;
 189         } else
 190                 ret = -EINVAL;
 191 error_ret:
 192         mutex_unlock(&st->lock);
 193
 194         return ret ? ret : len;
 195 }
 196
 197 static IIO_SCAN_EL_C(accel_x, 0, 0, NULL);
 198 static IIO_SCAN_EL_C(accel_y, 1, 0, NULL);
 199 static IIO_SCAN_EL_C(accel_z, 2, 0, NULL);
 200 static IIO_CONST_ATTR(accel_type_available, "s8/8 s11/16");
 201 static IIO_DEVICE_ATTR(accel_type,
 202                        S_IRUGO | S_IWUSR,
 203                        sca3000_show_ring_bpse,
 204                        sca3000_store_ring_bpse,
 205                        0);
 206
 207 static struct attribute *sca3000_scan_el_attrs[] = {
 208         &iio_scan_el_accel_x.dev_attr.attr,
 209         &iio_scan_el_accel_y.dev_attr.attr,
 210         &iio_scan_el_accel_z.dev_attr.attr,
 211         &iio_const_attr_accel_type_available.dev_attr.attr,
 212         &iio_dev_attr_accel_type.dev_attr.attr,
 213         NULL
 214 };
 215
 216 static struct attribute_group sca3000_scan_el_group = {
 217         .attrs = sca3000_scan_el_attrs,
 218         .name = "scan_elements",
 219 };
 220
 221 /*
 222  * Ring buffer attributes
 223  * This device is a bit unusual in that the sampling frequency and bpse
 224  * only apply to the ring buffer.  At all times full rate and accuracy
 225  * is available via direct reading from registers.
 226  */
 227 static struct attribute *sca3000_ring_attributes[] = {
 228         &dev_attr_length.attr,
 229         &dev_attr_bytes_per_datum.attr,
 230         &dev_attr_enable.attr,
 231         NULL,
 232 };
 233
 234 static struct attribute_group sca3000_ring_attr = {
 235         .attrs = sca3000_ring_attributes,
 236 };
 237
 238 static const struct attribute_group *sca3000_ring_attr_groups[] = {
 239         &sca3000_ring_attr,
 240         NULL
 241 };
 242
 243 static struct device_type sca3000_ring_type = {
 244         .release = sca3000_ring_release,
 245         .groups = sca3000_ring_attr_groups,
 246 };
 247
 248 static struct iio_ring_buffer *sca3000_rb_allocate(struct iio_dev *indio_dev)
 249 {
 250         struct iio_ring_buffer *buf;
 251         struct iio_hw_ring_buffer *ring;
 252
 253         ring = kzalloc(sizeof *ring, GFP_KERNEL);
 254         if (!ring)
 255                 return NULL;
 256         ring->private = indio_dev;
 257         buf = &ring->buf;
 258         iio_ring_buffer_init(buf, indio_dev);
 259         buf->dev.type = &sca3000_ring_type;
 260         device_initialize(&buf->dev);
 261         buf->dev.parent = &indio_dev->dev;
 262         dev_set_drvdata(&buf->dev, (void *)buf);
 263
 264         return buf;
 265 }
 266
 267 static inline void sca3000_rb_free(struct iio_ring_buffer *r)
 268 {
 269         if (r)
 270                 iio_put_ring_buffer(r);
 271 }
 272
 273 int sca3000_configure_ring(struct iio_dev *indio_dev)
 274 {
 275         indio_dev->ring = sca3000_rb_allocate(indio_dev);
 276         if (indio_dev->ring == NULL)
 277                 return -ENOMEM;
 278         indio_dev->modes |= INDIO_RING_HARDWARE_BUFFER;
 279
 280         indio_dev->ring->scan_el_attrs = &sca3000_scan_el_group;
 281         indio_dev->ring->access.rip_lots = &sca3000_rip_hw_rb;
 282         indio_dev->ring->access.get_length = &sca3000_ring_get_length;
 283         indio_dev->ring->access.get_bytes_per_datum = &sca3000_ring_get_bytes_per_datum;
 284
 285         return 0;
 286 }
 287
 288 void sca3000_unconfigure_ring(struct iio_dev *indio_dev)
 289 {
 290         sca3000_rb_free(indio_dev->ring);
 291 }
 292
 293 static inline
 294 int __sca3000_hw_ring_state_set(struct iio_dev *indio_dev, bool state)
 295 {
 296         struct sca3000_state *st = indio_dev->dev_data;
 297         int ret;
 298         u8 *rx;
 299
 300         mutex_lock(&st->lock);
 301         ret = sca3000_read_data(st, SCA3000_REG_ADDR_MODE, &rx, 1);
 302         if (ret)
 303                 goto error_ret;
 304         if (state) {
 305                 printk(KERN_INFO "supposedly enabling ring buffer\n");
 306                 ret = sca3000_write_reg(st,
 307                                         SCA3000_REG_ADDR_MODE,
 308                                         (rx[1] | SCA3000_RING_BUF_ENABLE));
 309         } else
 310                 ret = sca3000_write_reg(st,
 311                                         SCA3000_REG_ADDR_MODE,
 312                                         (rx[1] & ~SCA3000_RING_BUF_ENABLE));
 313         kfree(rx);
 314 error_ret:
 315         mutex_unlock(&st->lock);
 316
 317         return ret;
 318 }
 319 /**
 320  * sca3000_hw_ring_preenable() hw ring buffer preenable function
 321  *
 322  * Very simple enable function as the chip will allows normal reads
 323  * during ring buffer operation so as long as it is indeed running
 324  * before we notify the core, the precise ordering does not matter.
 325  **/
 326 static int sca3000_hw_ring_preenable(struct iio_dev *indio_dev)
 327 {
 328         return __sca3000_hw_ring_state_set(indio_dev, 1);
 329 }
 330
 331 static int sca3000_hw_ring_postdisable(struct iio_dev *indio_dev)
 332 {
 333         return __sca3000_hw_ring_state_set(indio_dev, 0);
 334 }
 335
 336 void sca3000_register_ring_funcs(struct iio_dev *indio_dev)
 337 {
 338         indio_dev->ring->preenable = &sca3000_hw_ring_preenable;
 339         indio_dev->ring->postdisable = &sca3000_hw_ring_postdisable;
 340 }
 341
 342 /**
 343  * sca3000_ring_int_process() ring specific interrupt handling.
 344  *
 345  * This is only split from the main interrupt handler so as to
 346  * reduce the amount of code if the ring buffer is not enabled.
 347  **/
 348 void sca3000_ring_int_process(u8 val, struct iio_ring_buffer *ring)
 349 {
 350         if (val & SCA3000_INT_STATUS_THREE_QUARTERS)
 351                 iio_push_or_escallate_ring_event(ring,
 352                                                  IIO_EVENT_CODE_RING_75_FULL,
 353                                                  0);
 354         else if (val & SCA3000_INT_STATUS_HALF)
 355                 iio_push_ring_event(ring,
 356                                     IIO_EVENT_CODE_RING_50_FULL, 0);
 357 }