Re: [U-Boot] [PATCH v5 7/8] riscv: sifive: fu540: Setup ethaddr env variable using OTP

[Bin Meng]

Hi Anup,

On Thu, Jun 20, 2019 at 2:49 PM Anup Patel <anup.pa...@wdc.com> wrote:
>
> This patch extends SiFive FU540 board support to setup ethaddr
> env variable based on board serialnum read from OTP.
>
> Signed-off-by: Anup Patel <anup.pa...@wdc.com>
> ---
>  board/sifive/fu540/fu540.c     | 118 +++++++++++++++++++++++++++++++++
>  configs/sifive_fu540_defconfig |   1 +
>  2 files changed, 119 insertions(+)
>
> diff --git a/board/sifive/fu540/fu540.c b/board/sifive/fu540/fu540.c
> index 5adc4a3d4a..81f2025402 100644
> --- a/board/sifive/fu540/fu540.c
> +++ b/board/sifive/fu540/fu540.c
> @@ -8,6 +8,124 @@
>
>  #include <common.h>
>  #include <dm.h>
> +#include <linux/delay.h>
> +#include <linux/io.h>
> +
> +#ifdef CONFIG_MISC_INIT_R
> +
> +#define FU540_OTP_BASE_ADDR                    0x10070000
> +
> +struct fu540_otp_regs {
> +       u32 pa;     /* Address input */
> +       u32 paio;   /* Program address input */
> +       u32 pas;    /* Program redundancy cell selection input */
> +       u32 pce;    /* OTP Macro enable input */
> +       u32 pclk;   /* Clock input */
> +       u32 pdin;   /* Write data input */
> +       u32 pdout;  /* Read data output */
> +       u32 pdstb;  /* Deep standby mode enable input (active low) */
> +       u32 pprog;  /* Program mode enable input */
> +       u32 ptc;    /* Test column enable input */
> +       u32 ptm;    /* Test mode enable input */
> +       u32 ptm_rep;/* Repair function test mode enable input */
> +       u32 ptr;    /* Test row enable input */
> +       u32 ptrim;  /* Repair function enable input */
> +       u32 pwe;    /* Write enable input (defines program cycle) */
> +} __packed;
> +
> +#define BYTES_PER_FUSE                         4
> +#define NUM_FUSES                              0x1000
> +
> +static int fu540_otp_read(int offset, void *buf, int size)
> +{
> +       struct fu540_otp_regs *regs = (void __iomem *)FU540_OTP_BASE_ADDR;
> +       unsigned int i;
> +       int fuseidx = offset / BYTES_PER_FUSE;
> +       int fusecount = size / BYTES_PER_FUSE;
> +       u32 fusebuf[fusecount];
> +
> +       /* check bounds */
> +       if (offset < 0 || size < 0)
> +               return -EINVAL;
> +       if (fuseidx >= NUM_FUSES)
> +               return -EINVAL;
> +       if ((fuseidx + fusecount) > NUM_FUSES)
> +               return -EINVAL;
> +
> +       /* init OTP */
> +       writel(0x01, &regs->pdstb); /* wake up from stand-by */
> +       writel(0x01, &regs->ptrim); /* enable repair function */
> +       writel(0x01, &regs->pce);   /* enable input */
> +
> +       /* read all requested fuses */
> +       for (i = 0; i < fusecount; i++, fuseidx++) {
> +               writel(fuseidx, &regs->pa);
> +
> +               /* cycle clock to read */
> +               writel(0x01, &regs->pclk);
> +               mdelay(1);
> +               writel(0x00, &regs->pclk);
> +               mdelay(1);
> +
> +               /* read the value */
> +               fusebuf[i] = readl(&regs->pdout);
> +       }
> +
> +       /* shut down */
> +       writel(0, &regs->pce);
> +       writel(0, &regs->ptrim);
> +       writel(0, &regs->pdstb);
> +
> +       /* copy out */
> +       memcpy(buf, fusebuf, size);
> +
> +       return 0;
> +}
> +
> +static u32 fu540_read_serialnum(void)
> +{
> +       int ret;
> +       u32 serial[2] = {0};
> +
> +       for (int i = 0xfe * 4; i > 0; i -= 8) {
> +               ret = fu540_otp_read(i, serial, sizeof(serial));
> +               if (ret) {
> +                       printf("%s: error reading from OTP\n", __func__);
> +                       break;
> +               }
> +               if (serial[0] == ~serial[1])
> +                       return serial[0];
> +       }
> +
> +       return 0;
> +}
> +
> +static void fu540_setup_macaddr(u32 serialnum)
> +{
> +       /* Default MAC address */
> +       unsigned char mac[6] = { 0x70, 0xb3, 0xd5, 0x92, 0xf0, 0x00 };

Why are the last 3 bytes of the default MAC address not zero? My
understanding is that the first 3 numbers indicate the vendor and
vendor is free to use the last 3 bytes for different devices.

> +
> +       /* OR the serial into the MAC -- see SiFive FSBL */
> +       mac[5] |= (serialnum >>  0) & 0xff;
> +       mac[4] |= (serialnum >>  8) & 0xff;
> +       mac[3] |= (serialnum >> 16) & 0xff;
> +
> +       /* Skip if environment variable already set */
> +       if (env_get("ethaddr"))
> +               return;

I think we should make the function clear by:
* ether move this logic to out of this function, and do such check in
misc_init_r()

OR
* unconditionally overwrite the "ethaddr" by removing this check

I am OK with either way.

> +
> +       /* Update environment variable */
> +       eth_env_set_enetaddr("ethaddr", mac);
> +}
> +
> +int misc_init_r(void)
> +{
> +       fu540_setup_macaddr(fu540_read_serialnum());
> +
> +       return 0;
> +}
> +
> +#endif
>

Regards,
Bin
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