1/*
2 * Copyright (C) 2016 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17#include <string.h>
18
19#include <nanohub/crc.h>
20#include <seos.h>
21
22#include <plat/pwr.h>
23
24struct StmCrcRegs {
25    volatile uint32_t DR;
26    volatile uint32_t IDR;
27    volatile uint32_t CR;
28};
29
30#define STM_CRC_CR_RESET        1
31
32static uint32_t mRevCrcTab[] =
33{
34        0x00000000, 0xB2B4BCB6, 0x61A864DB, 0xD31CD86D,
35        0xC350C9B6, 0x71E47500, 0xA2F8AD6D, 0x104C11DB,
36        0x82608EDB, 0x30D4326D, 0xE3C8EA00 ,0x517C56B6,
37        0x4130476D, 0xF384FBDB, 0x209823B6, 0x922C9F00
38};
39
40static uint32_t revCrc32Word(uint32_t crc, uint32_t data, uint32_t cnt)
41{
42    uint32_t i;
43
44    for (i = 0; i < cnt; i++)
45            crc = (crc >> 4) ^ mRevCrcTab[crc & 0x0F];
46
47    return crc ^ data;
48}
49
50static struct StmCrcRegs *mCrcRegs = (struct StmCrcRegs *)CRC_BASE;
51
52uint32_t crc32(const void *buf, size_t size, uint32_t crc)
53{
54    const uint32_t *words = (const uint32_t *)buf;
55    size_t numWords = size / 4;
56    unsigned int leftoverBytes = size % 4;
57    size_t i;
58
59    pwrUnitClock(PERIPH_BUS_AHB1, PERIPH_AHB1_CRC, true);
60
61    if (mCrcRegs->DR == crc)
62        ;
63    else if (crc == CRC_INIT)
64        mCrcRegs->CR = STM_CRC_CR_RESET;
65    else
66        mCrcRegs->DR = revCrc32Word(crc, mCrcRegs->DR, 8);
67
68    for (i = 0; i < numWords; i++)
69        mCrcRegs->DR = words[i];
70
71    if (leftoverBytes) {
72        uint32_t word = 0;
73        memcpy(&word, words + numWords, leftoverBytes);
74        /* n.b.: no shifting is needed, since the CRC block looks at the
75         * lowest byte first (i.e., we need the padding in the upper bytes)
76         */
77        mCrcRegs->DR = word;
78    }
79
80    crc = mCrcRegs->DR;
81    pwrUnitClock(PERIPH_BUS_AHB1, PERIPH_AHB1_CRC, false);
82    return crc;
83}
84