IXP42x rev. A0 support for network devices

Hi,

well, I finally found that old prototype board with IXP425 rev A0 and
I was even able to implant some modern RedBoot to it, so I gave it
a try.

It seems that a list of rev. A0 bugs (or "bugs") isn't that long after
all (those affecting Ethernet at least). Basically the QMgr IRQ status
is unreliable, and the undocumented "feature" register is write-only.

This patch is a bit of handcraft but it applies to 2.6.29 and
probably to older kernels.
Benoit, John, please let me know if it works or not. Thanks.

On Sun, Apr 26, 2009 at 5:58 PM, Krzysztof Halasa <khc@pm.waw.pl> wrote:
> Hi,
>
> well, I finally found that old prototype board with IXP425 rev A0 and
> I was even able to implant some modern RedBoot to it, so I gave it
> a try.
>
> It seems that a list of rev. A0 bugs (or "bugs") isn't that long after
> all (those affecting Ethernet at least). Basically the QMgr IRQ status
> is unreliable, and the undocumented "feature" register is write-only.
>
> This patch is a bit of handcraft but it applies to 2.6.29 and
> probably to older kernels.
> Benoit, John, please let me know if it works or not. Thanks.
> --
> Krzysztof Halasa
>
> --- a/arch/arm/mach-ixp4xx/include/mach/cpu.h
> +++ b/arch/arm/mach-ixp4xx/include/mach/cpu.h
> @@ -26,6 +26,8 @@
>  #define IXP46X_PROCESSOR_ID_VALUE      0x69054200
>  #define IXP46X_PROCESSOR_ID_MASK       0xfffffff0
>
> +#define cpu_is_ixp42x_rev_a0() ((read_cpuid_id() & (IXP4XX_PROCESSOR_ID_MASK | 0xF)) == \
> +                               IXP42X_PROCESSOR_ID_VALUE)
>  #define cpu_is_ixp42x()        ((read_cpuid_id() & IXP4XX_PROCESSOR_ID_MASK) == \
>                         IXP42X_PROCESSOR_ID_VALUE)
>  #define cpu_is_ixp43x()        ((read_cpuid_id() & IXP43X_PROCESSOR_ID_MASK) == \
> @@ -35,6 +35,9 @@
>  {
>        unsigned int val = ~*IXP4XX_EXP_CFG2;
>        val &= ~IXP4XX_FEATURE_RESERVED;
> +       if (cpu_is_ixp42x_rev_a0())
> +               return ~IXP4XX_FEATURE_IXP46X_ONLY & ~(IXP4XX_FEATURE_RCOMP |
> +                                                      IXP4XX_FEATURE_AES);
>        if (!cpu_is_ixp46x())
>                val &= ~IXP4XX_FEATURE_IXP46X_ONLY;
>
> --- a/arch/arm/mach-ixp4xx/ixp4xx_npe.c
> +++ b/arch/arm/mach-ixp4xx/ixp4xx_npe.c
> @@ -386,15 +386,6 @@ static int npe_reset(struct npe *npe)
>        /* reset the NPE */
>        ixp4xx_write_feature_bits(val &
>                                  ~(IXP4XX_FEATURE_RESET_NPEA << npe->id));
> -       for (i = 0; i < MAX_RETRIES; i++) {
> -               if (!(ixp4xx_read_feature_bits() &
> -                     (IXP4XX_FEATURE_RESET_NPEA << npe->id)))
> -                       break;  /* reset completed */
> -               udelay(1);
> -       }
> -       if (i == MAX_RETRIES)
> -               return -ETIMEDOUT;
> -
>        /* deassert reset */
>        ixp4xx_write_feature_bits(val |
>                                  (IXP4XX_FEATURE_RESET_NPEA << npe->id));
> --- a/arch/arm/mach-ixp4xx/ixp4xx_qmgr.c
> +++ b/arch/arm/mach-ixp4xx/ixp4xx_qmgr.c
> @@ -41,6 +41,31 @@ void qmgr_set_irq(unsigned int queue, int src,
>  }
>
>
> +static irqreturn_t qmgr_irq1_a0(int irq, void *pdev)
> +{
> +       int i, ret = 0;
> +
> +       /* ACK - it may also clear newly requested irqs so don't rely on it */
> +       __raw_writel(__raw_readl(&qmgr_regs->irqstat[0]),
> +                    &qmgr_regs->irqstat[0]);
> +
> +       for (i = 0; i < HALF_QUEUES; i++) {
> +               u32 src, stat;
> +               if (!(qmgr_regs->irqen[0] & BIT(i)))
> +                       continue;
> +               src = qmgr_regs->irqsrc[i >> 3];
> +               stat = qmgr_regs->stat1[i >> 3];
> +               if (src & 4) /* the IRQ condition is inverted */
> +                       stat = ~stat;
> +               if (stat & BIT(src & 3)) {
> +                       irq_handlers[i](irq_pdevs[i]);
> +                       ret = IRQ_HANDLED;
> +               }
> +       }
> +       return ret;
> +}
> +
> +
>  static irqreturn_t qmgr_irq1(int irq, void *pdev)
>  {
>        int i;
> @@ -250,8 +275,8 @@ static int qmgr_init(void)
>        for (i = 0; i < QUEUES; i++)
>                __raw_writel(0, &qmgr_regs->sram[i]);
>
> -       err = request_irq(IRQ_IXP4XX_QM1, qmgr_irq1, 0,
> -                         "IXP4xx Queue Manager", NULL);
> +       err = request_irq(IRQ_IXP4XX_QM1, cpu_is_ixp42x_rev_a0() ? qmgr_irq1_a0
> +                         : qmgr_irq1, 0, "IXP4xx Queue Manager", NULL);
>        if (err) {
>                printk(KERN_ERR "qmgr: failed to request IRQ%i\n",
>                       IRQ_IXP4XX_QM1);
>

Hi Krzysztof,

I should be able to test it, in a day.
Thank You!

John Woods
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