/*
 * Test RAM on an i.MX25 machine
 * 
 * Author: Baruch Siach <baruch@tkos.co.il>
 *
 * This is a standalone program which does not use any external library.
 * The RAM test algorithm that is implemented here is based on idea from the 
 * "Testing RAM in Embedded Systems" article at 
 * http://www.ganssle.com/testingram.htm
 */
#define MX25_UART1_BASE         0x43F90000
#define MX25_GPIO2_BASE         0x53FD0000

#define IOMUXC_BASE_ADDR        0x43FAC000
#define IOMUX_MUX_SD1_DATA2_PAD 0x1a0
#define IOMUX_PAD_SD1_DATA2_PAD 0x398

#define MX25_WDOG_BASE          0x53FDC000
#define MX25_WDOG_SEQ1          0x5555
#define MX25_WDOG_SEQ2          0xAAAA

#define RAM_BASE                0x80000000
#define RAM_SIZE                0x04000000

#define TEST_START_VALUE        0x55

#define writeb(v, a)    (*(volatile unsigned char *)(a)) = (v)
#define readb(a)        *(volatile unsigned char *)(a)

#define writew(v, a)    (*(volatile unsigned short *)(a)) = (v)
#define readw(a)        *(volatile unsigned short *)(a)

#define writel(v, a)    (*(volatile unsigned int *)(a)) = (v)
#define readl(a)        *(volatile unsigned int *)(a)

static char hex_tab[] = "0123456789abcdef";

__asm__ (".text\n"
        ".globl _start\n"
        "_start:\n"
        "ldr    sp, =0x78020000\n"
        "bl     main\n"
        "stop:\n"
        "b      stop\n"
        );

static void uart_putc (char c)
{
    while (readl (MX25_UART1_BASE + 0xb4) & 0x10)
        ;

    writel (c, MX25_UART1_BASE + 0x40);
}

static void uart_puthex (unsigned int val, int width)
{
    unsigned char digit;

    while (width-- > 0) {
        digit = (val >> (width*4)) & 0xf;
        uart_putc (hex_tab[digit]);
    }
}

static void uart_puts (char *str)
{
    for (; *str; str++) {
        if (*str == '\n')
            uart_putc ('\r');
        uart_putc (*str);
    }
}

static void watchdog_ping ()
{
    writew (MX25_WDOG_SEQ1, MX25_WDOG_BASE + 0x02);
    writew (MX25_WDOG_SEQ2, MX25_WDOG_BASE + 0x02);
}

static void reset_cpu ()
{
    unsigned short wcr = readw (MX25_WDOG_BASE);

    writew (wcr & 0xff, MX25_WDOG_BASE);
    watchdog_ping ();
}

static void __attribute__ ((unused)) led_on (void)
{
    /* set pad */
    writel (5, IOMUXC_BASE_ADDR + IOMUX_MUX_SD1_DATA2_PAD);
    writel (1, IOMUXC_BASE_ADDR + IOMUX_PAD_SD1_DATA2_PAD);

    /* set direction */
    writel (0x08000000, MX25_GPIO2_BASE + 4);
    /* set value */
    writel (0, MX25_GPIO2_BASE);
}

static void filler (unsigned char val, int cycle)
{
    unsigned int i;

    for (i = 0; i < RAM_SIZE; i++) {
        if ((i & 0xfffff) == 0) {
            uart_putc ('#');
            watchdog_ping ();
        }
        if (val == TEST_START_VALUE) {
            writeb(val, RAM_BASE + i);
            i++;
        }
        writeb(val, RAM_BASE + i);
        if (cycle)
            val++;
        else if (i & 1) /* negate bits on every 16bit write */
            val = ~val;
    }
    uart_puts ("\n");
}

static void check_err (unsigned long addr, unsigned char expect,
        unsigned char val)
{
    uart_puts ("Error at 0x");
    uart_puthex (addr, 8);
    uart_puts (" expected 0x");
    uart_puthex (expect, 2);
    uart_puts (", got 0x");
    uart_puthex (val, 2);
    uart_puts ("\n");
}

static int checker (int cycle)
{
    unsigned int i;
    unsigned char expected_val = TEST_START_VALUE;
    unsigned char ram_val;
    int err = 0;

    for (i = 0; i < RAM_SIZE; i++) {
        if ((i & 0xfffff) == 0) {
            uart_putc ('#');
            watchdog_ping ();
        }
        if (expected_val == TEST_START_VALUE) {
            ram_val = readb(RAM_BASE + i);
            if (ram_val != expected_val) {
                check_err (RAM_BASE + i, expected_val, ram_val);
                err++;
            }
            i++;
        }
        ram_val = readb(RAM_BASE + i);
        if (ram_val != expected_val) {
            check_err (RAM_BASE + i, expected_val, ram_val);
            err++;
        }
        if (err >= 10)
            return err;
        if (cycle)
            expected_val++;
        else if (i & 1) /* negate bits on every 16bit check */
            expected_val = ~expected_val;
    }
    uart_puts ("\n");

    return err;
}

int main (int argc, char *argv[])
{
    watchdog_ping ();

#ifdef TERMINATION_TEST
    if (argc > 1) {
        uart_puts ("Doing termination testing ");

        if (argv[1][0] == 'w') {
            unsigned char val;

            uart_puts ("(write)\n");

            if (argc == 3 && argv[2][0] == 'a')
                val = 0xAA;
            else
                val = TEST_START_VALUE;

            while (1)
                filler (val, 0);
        } else {
            uart_puts ("(read)\n");
            uart_puts ("Filling RAM...\n");
            filler (TEST_START_VALUE, 0);

            uart_puts ("Reading RAM...\n");
            while (1)
                checker (0);
        }
    }
#endif

    uart_puts ("Starting RAM write\n");
    filler (TEST_START_VALUE, 1);
    uart_puts ("Starting RAM read\n");
    if (checker (1) == 0)
        uart_puts ("RAM test finished successfully\n");
    else
        uart_puts ("RAM test failed\n");

    reset_cpu ();

    return 0;
}