isram-driver.c

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/*
 * Instruction SRAM accessor functions for the Blackfin
 *
 * Copyright 2008 Analog Devices Inc.
 *
 * Licensed under the GPL-2 or later
 */

#define pr_fmt(fmt) "isram: " fmt

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/types.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/sched.h>

#include <asm/blackfin.h>
#include <asm/dma.h>

/*
 * IMPORTANT WARNING ABOUT THESE FUNCTIONS
 *
 * The emulator will not function correctly if a write command is left in
 * ITEST_COMMAND or DTEST_COMMAND AND access to cache memory is needed by
 * the emulator. To avoid such problems, ensure that both ITEST_COMMAND
 * and DTEST_COMMAND are zero when exiting these functions.
 */


/*
 * On the Blackfin, L1 instruction sram (which operates at core speeds) can not
 * be accessed by a normal core load, so we need to go through a few hoops to
 * read/write it.
 * To try to make it easier - we export a memcpy interface, where either src or
 * dest can be in this special L1 memory area.
 * The low level read/write functions should not be exposed to the rest of the
 * kernel, since they operate on 64-bit data, and need specific address alignment
 */

static DEFINE_SPINLOCK(dtest_lock);

/* Takes a void pointer */
#define IADDR2DTEST(x) \
    ({ unsigned long __addr = (unsigned long)(x); \
        ((__addr & (1 << 11)) << (26 - 11)) | /* addr bit 11 (Way0/Way1)   */ \
        (1 << 24)                           | /* instruction access = 1    */ \
        ((__addr & (1 << 15)) << (23 - 15)) | /* addr bit 15 (Data Bank)   */ \
        ((__addr & (3 << 12)) << (16 - 12)) | /* addr bits 13:12 (Subbank) */ \
        (__addr & 0x47F8)                   | /* addr bits 14 & 10:3       */ \
        (1 << 2);                             /* data array = 1            */ \
    })

/* Takes a pointer, and returns the offset (in bits) which things should be shifted */
#define ADDR2OFFSET(x) ((((unsigned long)(x)) & 0x7) * 8)

/* Takes a pointer, determines if it is the last byte in the isram 64-bit data type */
#define ADDR2LAST(x) ((((unsigned long)x) & 0x7) == 0x7)

static void isram_write(const void *addr, uint64_t data)
{
    uint32_t cmd;
    unsigned long flags;

    if (unlikely(addr >= (void *)(L1_CODE_START + L1_CODE_LENGTH)))
        return;

    cmd = IADDR2DTEST(addr) | 2;             /* write */

    /*
     * Writes to DTEST_DATA[0:1] need to be atomic with write to DTEST_COMMAND
     * While in exception context - atomicity is guaranteed or double fault
     */
    spin_lock_irqsave(&dtest_lock, flags);

    bfin_write_DTEST_DATA0(data & 0xFFFFFFFF);
    bfin_write_DTEST_DATA1(data >> 32);

    /* use the builtin, since interrupts are already turned off */
    __builtin_bfin_csync();
    bfin_write_DTEST_COMMAND(cmd);
    __builtin_bfin_csync();

    bfin_write_DTEST_COMMAND(0);
    __builtin_bfin_csync();

    spin_unlock_irqrestore(&dtest_lock, flags);
}

static uint64_t isram_read(const void *addr)
{
    uint32_t cmd;
    unsigned long flags;
    uint64_t ret;

    if (unlikely(addr > (void *)(L1_CODE_START + L1_CODE_LENGTH)))
        return 0;

    cmd = IADDR2DTEST(addr) | 0;              /* read */

    /*
     * Reads of DTEST_DATA[0:1] need to be atomic with write to DTEST_COMMAND
     * While in exception context - atomicity is guaranteed or double fault
     */
    spin_lock_irqsave(&dtest_lock, flags);
    /* use the builtin, since interrupts are already turned off */
    __builtin_bfin_csync();
    bfin_write_DTEST_COMMAND(cmd);
    __builtin_bfin_csync();
    ret = bfin_read_DTEST_DATA0() | ((uint64_t)bfin_read_DTEST_DATA1() << 32);

    bfin_write_DTEST_COMMAND(0);
    __builtin_bfin_csync();
    spin_unlock_irqrestore(&dtest_lock, flags);

    return ret;
}

static bool isram_check_addr(const void *addr, size_t n)
{
    if ((addr >= (void *)L1_CODE_START) &&
        (addr < (void *)(L1_CODE_START + L1_CODE_LENGTH))) {
        if (unlikely((addr + n) > (void *)(L1_CODE_START + L1_CODE_LENGTH))) {
            show_stack(NULL, NULL);
            pr_err("copy involving %p length (%zu) too long\n", addr, n);
        }
        return true;
    }
    return false;
}

/*
 * The isram_memcpy() function copies n bytes from memory area src to memory area dest.
 * The isram_memcpy() function returns a pointer to dest.
 * Either dest or src can be in L1 instruction sram.
 */
void *isram_memcpy(void *dest, const void *src, size_t n)
{
    uint64_t data_in = 0, data_out = 0;
    size_t count;
    bool dest_in_l1, src_in_l1, need_data, put_data;
    unsigned char byte, *src_byte, *dest_byte;

    src_byte = (unsigned char *)src;
    dest_byte = (unsigned char *)dest;

    dest_in_l1 = isram_check_addr(dest, n);
    src_in_l1 = isram_check_addr(src, n);

    need_data = true;
    put_data = true;
    for (count = 0; count < n; count++) {
        if (src_in_l1) {
            if (need_data) {
                data_in = isram_read(src + count);
                need_data = false;
            }

            if (ADDR2LAST(src + count))
                need_data = true;

            byte = (unsigned char)((data_in >> ADDR2OFFSET(src + count)) & 0xff);

        } else {
            /* src is in L2 or L3 - so just dereference*/
            byte = src_byte[count];
        }

        if (dest_in_l1) {
            if (put_data) {
                data_out = isram_read(dest + count);
                put_data = false;
            }

            data_out &= ~((uint64_t)0xff << ADDR2OFFSET(dest + count));
            data_out |= ((uint64_t)byte << ADDR2OFFSET(dest + count));

            if (ADDR2LAST(dest + count)) {
                put_data = true;
                isram_write(dest + count, data_out);
            }
        } else {
            /* dest in L2 or L3 - so just dereference */
            dest_byte[count] = byte;
        }
    }

    /* make sure we dump the last byte if necessary */
    if (dest_in_l1 && !put_data)
        isram_write(dest + count, data_out);

    return dest;
}
EXPORT_SYMBOL(isram_memcpy);

#ifdef CONFIG_BFIN_ISRAM_SELF_TEST

static int test_len = 0x20000;

static __init void hex_dump(unsigned char *buf, int len)
{
    while (len--)
        pr_cont("%02x", *buf++);
}

static __init int isram_read_test(char *sdram, void *l1inst)
{
    int i, ret = 0;
    uint64_t data1, data2;

    pr_info("INFO: running isram_read tests\n");

    /* setup some different data to play with */
    for (i = 0; i < test_len; ++i)
        sdram[i] = i % 255;
    dma_memcpy(l1inst, sdram, test_len);

    /* make sure we can read the L1 inst */
    for (i = 0; i < test_len; i += sizeof(uint64_t)) {
        data1 = isram_read(l1inst + i);
        memcpy(&data2, sdram + i, sizeof(data2));
        if (data1 != data2) {
            pr_err("FAIL: isram_read(%p) returned %#llx but wanted %#llx\n",
                l1inst + i, data1, data2);
            ++ret;
        }
    }

    return ret;
}

static __init int isram_write_test(char *sdram, void *l1inst)
{
    int i, ret = 0;
    uint64_t data1, data2;

    pr_info("INFO: running isram_write tests\n");

    /* setup some different data to play with */
    memset(sdram, 0, test_len * 2);
    dma_memcpy(l1inst, sdram, test_len);
    for (i = 0; i < test_len; ++i)
        sdram[i] = i % 255;

    /* make sure we can write the L1 inst */
    for (i = 0; i < test_len; i += sizeof(uint64_t)) {
        memcpy(&data1, sdram + i, sizeof(data1));
        isram_write(l1inst + i, data1);
        data2 = isram_read(l1inst + i);
        if (data1 != data2) {
            pr_err("FAIL: isram_write(%p, %#llx) != %#llx\n",
                l1inst + i, data1, data2);
            ++ret;
        }
    }

    dma_memcpy(sdram + test_len, l1inst, test_len);
    if (memcmp(sdram, sdram + test_len, test_len)) {
        pr_err("FAIL: isram_write() did not work properly\n");
        ++ret;
    }

    return ret;
}

static __init int
_isram_memcpy_test(char pattern, void *sdram, void *l1inst, const char *smemcpy,
                   void *(*fmemcpy)(void *, const void *, size_t))
{
    memset(sdram, pattern, test_len);
    fmemcpy(l1inst, sdram, test_len);
    fmemcpy(sdram + test_len, l1inst, test_len);
    if (memcmp(sdram, sdram + test_len, test_len)) {
        pr_err("FAIL: %s(%p <=> %p, %#x) failed (data is %#x)\n",
            smemcpy, l1inst, sdram, test_len, pattern);
        return 1;
    }
    return 0;
}
#define _isram_memcpy_test(a, b, c, d) _isram_memcpy_test(a, b, c, #d, d)

static __init int isram_memcpy_test(char *sdram, void *l1inst)
{
    int i, j, thisret, ret = 0;

    /* check broad isram_memcpy() */
    pr_info("INFO: running broad isram_memcpy tests\n");
    for (i = 0xf; i >= 0; --i)
        ret += _isram_memcpy_test(i, sdram, l1inst, isram_memcpy);

    /* check read of small, unaligned, and hardware 64bit limits */
    pr_info("INFO: running isram_memcpy (read) tests\n");

    /* setup some different data to play with */
    for (i = 0; i < test_len; ++i)
        sdram[i] = i % 255;
    dma_memcpy(l1inst, sdram, test_len);

    thisret = 0;
    for (i = 0; i < test_len - 32; ++i) {
        unsigned char cmp[32];
        for (j = 1; j <= 32; ++j) {
            memset(cmp, 0, sizeof(cmp));
            isram_memcpy(cmp, l1inst + i, j);
            if (memcmp(cmp, sdram + i, j)) {
                pr_err("FAIL: %p:", l1inst + 1);
                hex_dump(cmp, j);
                pr_cont(" SDRAM:");
                hex_dump(sdram + i, j);
                pr_cont("\n");
                if (++thisret > 20) {
                    pr_err("FAIL: skipping remaining series\n");
                    i = test_len;
                    break;
                }
            }
        }
    }
    ret += thisret;

    /* check write of small, unaligned, and hardware 64bit limits */
    pr_info("INFO: running isram_memcpy (write) tests\n");

    memset(sdram + test_len, 0, test_len);
    dma_memcpy(l1inst, sdram + test_len, test_len);

    thisret = 0;
    for (i = 0; i < test_len - 32; ++i) {
        unsigned char cmp[32];
        for (j = 1; j <= 32; ++j) {
            isram_memcpy(l1inst + i, sdram + i, j);
            dma_memcpy(cmp, l1inst + i, j);
            if (memcmp(cmp, sdram + i, j)) {
                pr_err("FAIL: %p:", l1inst + i);
                hex_dump(cmp, j);
                pr_cont(" SDRAM:");
                hex_dump(sdram + i, j);
                pr_cont("\n");
                if (++thisret > 20) {
                    pr_err("FAIL: skipping remaining series\n");
                    i = test_len;
                    break;
                }
            }
        }
    }
    ret += thisret;

    return ret;
}

static __init int isram_test_init(void)
{
    int ret;
    char *sdram;
    void *l1inst;

    /* Try to test as much of L1SRAM as possible */
    while (test_len) {
        test_len >>= 1;
        l1inst = l1_inst_sram_alloc(test_len);
        if (l1inst)
            break;
    }
    if (!l1inst) {
        pr_warning("SKIP: could not allocate L1 inst\n");
        return 0;
    }
    pr_info("INFO: testing %#x bytes (%p - %p)\n",
            test_len, l1inst, l1inst + test_len);

    sdram = kmalloc(test_len * 2, GFP_KERNEL);
    if (!sdram) {
        sram_free(l1inst);
        pr_warning("SKIP: could not allocate sdram\n");
        return 0;
    }

    /* sanity check initial L1 inst state */
    ret = 1;
    pr_info("INFO: running initial dma_memcpy checks %p\n", sdram);
    if (_isram_memcpy_test(0xa, sdram, l1inst, dma_memcpy))
        goto abort;
    if (_isram_memcpy_test(0x5, sdram, l1inst, dma_memcpy))
        goto abort;

    ret = 0;
    ret += isram_read_test(sdram, l1inst);
    ret += isram_write_test(sdram, l1inst);
    ret += isram_memcpy_test(sdram, l1inst);

 abort:
    sram_free(l1inst);
    kfree(sdram);

    if (ret)
        return -EIO;

    pr_info("PASS: all tests worked !\n");
    return 0;
}
late_initcall(isram_test_init);

static __exit void isram_test_exit(void)
{
    /* stub to allow unloading */
}
module_exit(isram_test_exit);

#endif