[PATCH 1/3] usb: ehci: add freescale imx28 special write register method

[Fabio Estevam]

Hi Peter,

On Wed, Oct 23, 2013 at 6:35 AM, Peter Chen <peter.chen at freescale.com> wrote:
> According to Freescale imx28 Errata, "ENGR119653 USB: ARM to USB
> register error issue", All USB register write operations must
> use the ARM SWP instruction. So, we implement a special ehci_write
> for imx28.
>
> Discussion for it at below:
> http://marc.info/?l=linux-usb&m=137996395529294&w=2
>
> Signed-off-by: Peter Chen <peter.chen at freescale.com>
> ---
>  drivers/usb/host/ehci.h |   13 +++++++++++++
>  1 files changed, 13 insertions(+), 0 deletions(-)
>
> diff --git a/drivers/usb/host/ehci.h b/drivers/usb/host/ehci.h
> index 2d40192..577b75d 100644
> --- a/drivers/usb/host/ehci.h
> +++ b/drivers/usb/host/ehci.h
> @@ -203,6 +203,7 @@ struct ehci_hcd {                   /* one per controller */
>         unsigned                has_synopsys_hc_bug:1; /* Synopsys HC */
>         unsigned                frame_index_bug:1; /* MosChip (AKA NetMos) */
>         unsigned                need_oc_pp_cycle:1; /* MPC834X port power */
> +       unsigned                imx28_write_fix:1; /* For Freescale i.MX28 */
>
>         /* required for usb32 quirk */
>         #define OHCI_CTRL_HCFS          (3 << 6)
> @@ -680,6 +681,13 @@ static inline unsigned int ehci_readl(const struct ehci_hcd *ehci,
>  #endif
>  }
>
> +#ifdef CONFIG_SOC_IMX28
> +static inline void imx28_ehci_writel(u32 val32, volatile u32 *addr)
> +{
> +       __asm__ ("swp %0, %0, [%1]" : : "r"(val32), "r"(addr));
> +}
> +#endif
> +
>  static inline void ehci_writel(const struct ehci_hcd *ehci,
>                 const unsigned int val, __u32 __iomem *regs)
>  {
> @@ -687,6 +695,11 @@ static inline void ehci_writel(const struct ehci_hcd *ehci,
>         ehci_big_endian_mmio(ehci) ?
>                 writel_be(val, regs) :
>                 writel(val, regs);
> +#elif defined(CONFIG_SOC_IMX28)
> +       if (ehci->imx28_write_fix)
> +               imx28_ehci_writel(val, regs);
> +       else
> +               writel(val, regs);

Have you tested this on mx23?

What if we have a kernel built for both mx23 and mx28?

Regards,

Fabio Estevam