[PATCH] Add new command fs2bridge for socfpga

[Mabcded Babcde]

2017-07-27 20:14 GMT+02:00 Trent Piepho <tpiepho at kymetacorp.com>:
> On Thu, 2017-07-27 at 18:20 +0200, Mabcded Babcde wrote:
>> Hi,
>> this patch adds a new command to barebox. It is used to enable or
>> disable the fpga-to-sdram bridges on socfpgas. The patch is based on a
>> manual from altera
>
> I wonder if this might be better as a settable parameter of the fpga
> device?
>

Ok, but how can I then ensure that the SDRAM is completly idle?

>> +
>> +#define SOCFPGA_SYSMGR_ADDRESS    0xFFD08000
>> +#define SOCFPGA_SDR_ADDRESS    0xFFC20000
>> +
>> +#define SDR_CTRLGRP_FPGAPORTRST_ADDRESS    0x5080
>> +#define SDR_CTRLGRP_STATICCFG_ADDRESS    0x505C
>> +#define SDR_CTRLGRP_STATICCFG_APPLYCFG_MASK    0x00000008
>> +
>> +#define SYSMGR_FPGAINTF_MODULE    (SOCFPGA_SYSMGR_ADDRESS + 0x28)
>
> You should be able to get these addresses from socfpga-regs.h and
> system-manager.h
>

Thanks for the hint, I included mach/cyclone5-regs,
mach/cyclone5-sdram.h and cyclone5-system-manager.
But I did't find socfpga-regs.h and system-manager.h.

>> +
>> +
>> +static void socfpga_sdram_apply_staticcfg(void)
>> +{
>> +    const uint32_t staticcfg = SOCFPGA_SDR_ADDRESS +
>> SDR_CTRLGRP_STATICCFG_ADDRESS;
>> +    const uint32_t applymask = SDR_CTRLGRP_STATICCFG_APPLYCFG_MASK;
>> +    uint32_t val = readl(staticcfg) | applymask;
>> +
>> +    /*
>> +     * SDRAM staticcfg register specific:
>> +     * When applying the register setting, the CPU must not access
>> +     * SDRAM. Luckily for us, we can abuse i-cache here to help us
>> +     * circumvent the SDRAM access issue. The idea is to make sure
>> +     * that the code is in one full i-cache line by branching past
>> +     * it and back. Once it is in the i-cache, we execute the core
>> +     * of the code and apply the register settings.
>> +     *
>> +     * The code below uses 7 instructions, while the Cortex-A9 has
>> +     * 32-byte cachelines, thus the limit is 8 instructions total.
>> +     */
>> +    asm volatile(
>> +        ".align    5            \n"
>> +        "    b    2f        \n"
>> +        "1:    str    %0,    [%1]    \n"
>> +        "    dsb            \n"
>> +        "    isb            \n"
>> +        "    b    3f        \n"
>> +        "2:    b    1b        \n"
>> +        "3:    nop            \n"
>> +    : : "r"(val), "r"(staticcfg) : "memory", "cc");
>> +}
>> +
>> +
>> +int do_f2sbridge(int argc, char *argv[])
>> +{
>> +    if (argc != 2)
>> +        return COMMAND_ERROR_USAGE;
>> +
>> +    switch (*argv[1]) {
>> +    case 'e':    // Enable
>> +        // hps peripheral controller to fpga
>> +        iowrite32(0, SYSMGR_FPGAINTF_MODULE);
>
> Why disable FPGA access to the emacs?  Is that required too?
>

In the altera code it is also disabled. But I tried it without the
line and the bridges seem to be enabled.

>> +        socfpga_sdram_apply_staticcfg();
>> +        // enable all fpga2sdram bridge ports
>> +        iowrite32(0x3fff, SOCFPGA_SDR_ADDRESS +
>> SDR_CTRLGRP_FPGAPORTRST_ADDRESS);
>> +
>> +        break;
>> +    case 'd':    // Disable
>> +        iowrite32(0, SYSMGR_FPGAINTF_MODULE);
>> +        iowrite32(0, SOCFPGA_SDR_ADDRESS + SDR_CTRLGRP_FPGAPORTRST_ADDRESS);
>> +        socfpga_sdram_apply_staticcfg();
>> +
>> +        break;
>> +    default:
>> +        return COMMAND_ERROR_USAGE;
>> +    }
>> +
>> +    return 0;
>> +}
>> +
>> +
>> +BAREBOX_CMD_HELP_START(f2sbridge)
>> +BAREBOX_CMD_HELP_TEXT("Options:")
>> +BAREBOX_CMD_HELP_OPT ("-e \t",  "enable f2s bridge")
>> +BAREBOX_CMD_HELP_OPT ("-d \t",  "disable f2s bridge")
>> +BAREBOX_CMD_HELP_END
>> +
>> +BAREBOX_CMD_START(f2sbridge)
>> +    .cmd        = do_f2sbridge,
>> +    BAREBOX_CMD_DESC("Enables or disables the fpga2sdram bridge.")
>> +    BAREBOX_CMD_GROUP(CMD_GRP_MISC)
>> +    BAREBOX_CMD_HELP(cmd_f2sbridge_help)
>> +BAREBOX_CMD_END
>