[PATCH v3 4/8] powerpc/xive: introduce xive_esb_write()

[Benjamin Herrenschmidt]

On Wed, 2017-08-30 at 21:46 +0200, Cédric Le Goater wrote:
> Some source support MMIO stores on the ESB page to perform EOI. Let's
> introduce a specific routine for this case even if this should be the
> only use of it.
> 
> Signed-off-by: Cédric Le Goater <clg at kaod.org>
> Reviewed-by: David Gibson <david at gibson.dropbear.id.au>
Acked-by: Benjamin Herrenschmidt <benh at kernel.crashing.org>

> ---
>  arch/powerpc/sysdev/xive/common.c | 11 ++++++++++-
>  1 file changed, 10 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/powerpc/sysdev/xive/common.c b/arch/powerpc/sysdev/xive/common.c
> index 8a58662ed793..ac5f18a66742 100644
> --- a/arch/powerpc/sysdev/xive/common.c
> +++ b/arch/powerpc/sysdev/xive/common.c
> @@ -203,6 +203,15 @@ static u8 xive_esb_read(struct xive_irq_data *xd, u32 offset)
>  	return (u8)val;
>  }
>  
> +static void xive_esb_write(struct xive_irq_data *xd, u32 offset, u64 data)
> +{
> +	/* Handle HW errata */
> +	if (xd->flags & XIVE_IRQ_FLAG_SHIFT_BUG)
> +		offset |= offset << 4;
> +
> +	out_be64(xd->eoi_mmio + offset, data);
> +}
> +
>  #ifdef CONFIG_XMON
>  static void xive_dump_eq(const char *name, struct xive_q *q)
>  {
> @@ -297,7 +306,7 @@ void xive_do_source_eoi(u32 hw_irq, struct xive_irq_data *xd)
>  {
>  	/* If the XIVE supports the new "store EOI facility, use it */
>  	if (xd->flags & XIVE_IRQ_FLAG_STORE_EOI)
> -		out_be64(xd->eoi_mmio + XIVE_ESB_STORE_EOI, 0);
> +		xive_esb_write(xd, XIVE_ESB_STORE_EOI, 0);
>  	else if (hw_irq && xd->flags & XIVE_IRQ_FLAG_EOI_FW) {
>  		/*
>  		 * The FW told us to call it. This happens for some