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Kernel driver ads7828
=====================

Supported chips:
  * Texas Instruments/Burr-Brown ADS7828
    Prefix: 'ads7828'
    Datasheet: Publicly available at the Texas Instruments website:
               http://focus.ti.com/lit/ds/symlink/ads7828.pdf

  * Texas Instruments ADS7830
    Prefix: 'ads7830'
    Datasheet: Publicly available at the Texas Instruments website:
               http://focus.ti.com/lit/ds/symlink/ads7830.pdf

Authors:
        Steve Hardy <shardy@redhat.com>
        Vivien Didelot <vivien.didelot@savoirfairelinux.com>
        Guillaume Roguez <guillaume.roguez@savoirfairelinux.com>

Platform data
-------------

The ads7828 driver accepts an optional ads7828_platform_data structure (defined
in include/linux/platform_data/ads7828.h). The structure fields are:

* diff_input: (bool) Differential operation
  set to true for differential mode, false for default single ended mode.

* ext_vref: (bool) External reference
  set to true if it operates with an external reference, false for default
  internal reference.

* vref_mv: (unsigned int) Voltage reference
  if using an external reference, set this to the reference voltage in mV,
  otherwise it will default to the internal value (2500mV). This value will be
  bounded with limits accepted by the chip, described in the datasheet.

 If no structure is provided, the configuration defaults to single ended
 operation and internal voltage reference (2.5V).

Description
-----------

This driver implements support for the Texas Instruments ADS7828 and ADS7830.

The ADS7828 device is a 12-bit 8-channel A/D converter, while the ADS7830 does
8-bit sampling.

It can operate in single ended mode (8 +ve inputs) or in differential mode,
where 4 differential pairs can be measured.

The chip also has the facility to use an external voltage reference.  This
may be required if your hardware supplies the ADS7828 from a 5V supply, see
the datasheet for more details.

There is no reliable way to identify this chip, so the driver will not scan
some addresses to try to auto-detect it. That means that you will have to
statically declare the device in the platform support code.
"AS IS" BASIS, // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. // See the License for the specific language governing permissions and // limitations under the License. */ #include <stdlib.h> #include <inttypes.h> #include <rte_cycles.h> #include "prox_malloc.h" #include "cdf.h" static uint32_t round_pow2(uint32_t val) { uint32_t ret; uint32_t s = 1 << 31; while ((s & val) == 0) s = s >> 1; if (s == 1U << 31 && s != val) return 0; ret = val; if (s != ret) ret = (s << 1); return ret; } static uint32_t get_r_max(struct cdf *cdf, uint32_t cur) { uint32_t right_child = cur; do { cur = right_child; right_child = cur * 2 + 1; } while (right_child < cdf->elems[0]); return cdf->elems[cur]; } struct cdf *cdf_create(uint32_t n_vals, int socket_id) { struct cdf *ret; size_t mem_size = 0; uint32_t n_vals_round = round_pow2(n_vals); if (0 == n_vals_round) return NULL; mem_size += sizeof(struct cdf); mem_size += sizeof(((struct cdf *)(0))->elems[0]) * n_vals_round * 2; ret = prox_zmalloc(mem_size, socket_id); ret->elems[0] = n_vals; /* leafs are [n_vals, 2 * n_vals[. During cdf_add() and cdf_setup(), rand_max refers to the index of the next leaf to be added. */ ret->rand_max = n_vals_round; ret->first_child = n_vals_round; ret->seed = rte_rdtsc(); return ret; } void cdf_add(struct cdf *cdf, uint32_t len) { cdf->elems[cdf->rand_max++] = len; } int cdf_setup(struct cdf *cdf) { uint32_t last_leaf, first_leaf; uint32_t first_parent, last_parent; uint32_t total, multiplier, cur, end; if (cdf->elems[0] == 1) { cdf->rand_max = RAND_MAX; cdf->elems[1] = RAND_MAX; cdf->elems[0] = 2; return 0; } last_leaf = cdf->rand_max; first_leaf = round_pow2(cdf->elems[0]); /* Failed to add all elements through cdf_add() */ if (last_leaf - first_leaf != cdf->elems[0]) return -1; total = 0; for (uint32_t i = first_leaf; i < last_leaf; ++i) { total += cdf->elems[i]; } multiplier = RAND_MAX / total; if (multiplier * total == RAND_MAX) multiplier--; cdf->rand_max = multiplier * total; total = 0; for (uint32_t i = first_leaf; i < last_leaf; ++i) { uint32_t cur = cdf->elems[i]; /* Each element represents the range between previous total (non-inclusive) and new total (inclusive). */ total += cur * multiplier - 1; cdf->elems[i] = total; total += 1; } end = round_pow2(first_leaf) << 1; for (uint32_t i = last_leaf; i < end; ++i) { cdf->elems[i] = RAND_MAX; } cdf->first_child = first_leaf; cdf->elems[0] = end; /* Build the binary tree used at run-time. */ last_leaf = end - 1; do { first_parent = first_leaf/2; last_parent = last_leaf/2; for (uint32_t i = first_parent; i <= last_parent; ++i) { /* The current nodes value should be the biggest value accessible through its left child. This value is stored in the right most child of the left child. The left most child of the right child is the first value that can not be accessed through the left child. */ cdf->elems[i] = get_r_max(cdf, i * 2); } first_leaf = first_parent; last_leaf = last_parent; } while (first_parent != last_parent); return 0; }