Re: [PATCH v4 22/25] ppc/xive: Introduce a xive_os_cam_decode() helper

[David Gibson <david@gibson.dropbear.id.au>]

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On Wed, Sep 18, 2019 at 06:06:42PM +0200, Cédric Le Goater wrote:
> The OS CAM line has a special encoding exploited by the HW. Provide a
> helper routine to hide the details to the TIMA command handlers. This
> also clarifies the endian ness of different variables : 'qw1w2' is
> big-endian and 'cam' is native.
> 
> Signed-off-by: Cédric Le Goater <clg@kaod.org>
> ---
>  hw/intc/xive.c | 35 ++++++++++++++++++++++++++---------
>  1 file changed, 26 insertions(+), 9 deletions(-)
> 
> diff --git a/hw/intc/xive.c b/hw/intc/xive.c
> index dfae584a319f..cdc4ea8b0e51 100644
> --- a/hw/intc/xive.c
> +++ b/hw/intc/xive.c
> @@ -342,14 +342,29 @@ static void xive_tm_set_os_pending(XivePresenter *xptr, XiveTCTX *tctx,
>      xive_tctx_ipb_update(tctx, TM_QW1_OS, priority_to_ipb(value & 0xff));
>  }
>  
> +static void xive_os_cam_decode(uint32_t cam, uint8_t *nvt_blk,
> +                               uint32_t *nvt_idx, bool *vo)
> +{
> +    *nvt_blk = xive_nvt_blk(cam);
> +    *nvt_idx = xive_nvt_idx(cam);
> +    *vo = !!(cam & TM_QW1W2_VO);
> +}
> +
>  static uint64_t xive_tm_pull_os_ctx(XivePresenter *xptr, XiveTCTX *tctx,
>                                      hwaddr offset, unsigned size)
>  {
> -    uint32_t qw1w2_prev = xive_tctx_word2(&tctx->regs[TM_QW1_OS]);
> -    uint32_t qw1w2;
> +    uint32_t qw1w2 = xive_tctx_word2(&tctx->regs[TM_QW1_OS]);
> +    uint32_t qw1w2_new;
> +    uint32_t cam = be32_to_cpu(qw1w2);
> +    uint8_t nvt_blk;
> +    uint32_t nvt_idx;
> +    bool vo;
>  
> -    qw1w2 = xive_set_field32(TM_QW1W2_VO, qw1w2_prev, 0);
> -    memcpy(&tctx->regs[TM_QW1_OS + TM_WORD2], &qw1w2, 4);

I'd kind of prefer to fold both the memcpy and the endian swizzle into
a read/write_register_word helper of some sort.

> +    xive_os_cam_decode(cam, &nvt_blk, &nvt_idx, &vo);
> +
> +    /* Invalidate CAM line */
> +    qw1w2_new = xive_set_field32(TM_QW1W2_VO, qw1w2, 0);
> +    memcpy(&tctx->regs[TM_QW1_OS + TM_WORD2], &qw1w2_new, 4);
>      return qw1w2;
>  }
>  
> @@ -387,13 +402,15 @@ static void xive_tctx_need_resend(XiveRouter *xrtr, XiveTCTX *tctx,
>  static void xive_tm_push_os_ctx(XivePresenter *xptr, XiveTCTX *tctx,
>                                  hwaddr offset, uint64_t value, unsigned size)
>  {
> -    uint32_t qw1w2 = value;
> -    uint8_t nvt_blk = xive_nvt_blk(qw1w2);
> -    uint32_t nvt_idx = xive_nvt_idx(qw1w2);
> -    bool vo = !!(qw1w2 & TM_QW1W2_VO);
> +    uint32_t cam = value;
> +    uint32_t qw1w2 = cpu_to_be32(cam);
> +    uint8_t nvt_blk;
> +    uint32_t nvt_idx;
> +    bool vo;
> +
> +    xive_os_cam_decode(cam, &nvt_blk, &nvt_idx, &vo);
>  
>      /* First update the registers */
> -    qw1w2 = cpu_to_be32(qw1w2);
>      memcpy(&tctx->regs[TM_QW1_OS + TM_WORD2], &qw1w2, 4);
>  
>      /* Check the interrupt pending bits */

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson

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