On Fri, Mar 15, 2013 at 08:59:55AM -0400, Eduardo Valentin wrote:
> This patch introduce a macro to read, update, write bitfields.
> It will be specific to bandgap data structures.
> 
> Signed-off-by: Eduardo Valentin <eduardo.valen...@ti.com>
> ---
>  drivers/staging/omap-thermal/omap-bandgap.c |  178 
> +++++++--------------------
>  1 files changed, 46 insertions(+), 132 deletions(-)
> 
> diff --git a/drivers/staging/omap-thermal/omap-bandgap.c 
> b/drivers/staging/omap-thermal/omap-bandgap.c
> index 9f2d7cc..1c1b905 100644
> --- a/drivers/staging/omap-thermal/omap-bandgap.c
> +++ b/drivers/staging/omap-thermal/omap-bandgap.c
> @@ -52,25 +52,29 @@ static void omap_bandgap_writel(struct omap_bandgap 
> *bg_ptr, u32 val, u32 reg)
>       writel(val, bg_ptr->base + reg);
>  }
>  
> +/* update bits, value will be shifted */
> +#define RMW_BITS(bg_ptr, id, reg, mask, val)                 \
> +do {                                                         \
> +     struct temp_sensor_registers *t;                        \
> +     u32 r;                                                  \
> +                                                             \
> +     t = bg_ptr->conf->sensors[(id)].registers;              \
> +     r = omap_bandgap_readl(bg_ptr, t->reg);                 \
> +     r &= ~t->mask;                                          \
> +     r |= (val) << __ffs(t->mask);                           \
> +     omap_bandgap_writel(bg_ptr, r, t->reg);                 \
> +} while (0)
> +
>  static int omap_bandgap_power(struct omap_bandgap *bg_ptr, bool on)
>  {
> -     struct temp_sensor_registers *tsr;
>       int i;
> -     u32 ctrl;
>  
>       if (!OMAP_BANDGAP_HAS(bg_ptr, POWER_SWITCH))
>               return 0;
>  
> -     for (i = 0; i < bg_ptr->conf->sensor_count; i++) {
> -             tsr = bg_ptr->conf->sensors[i].registers;
> -             ctrl = omap_bandgap_readl(bg_ptr, tsr->temp_sensor_ctrl);
> -             ctrl &= ~tsr->bgap_tempsoff_mask;
> +     for (i = 0; i < bg_ptr->conf->sensor_count; i++)
>               /* active on 0 */
> -             ctrl |= !on << __ffs(tsr->bgap_tempsoff_mask);
> -
> -             /* write BGAP_TEMPSOFF should be reset to 0 */
> -             omap_bandgap_writel(bg_ptr, ctrl, tsr->temp_sensor_ctrl);
> -     }
> +             RMW_BITS(bg_ptr, i, temp_sensor_ctrl, bgap_tempsoff_mask, !on);
>  
>       return 0;
>  }
> @@ -78,15 +82,13 @@ static int omap_bandgap_power(struct omap_bandgap 
> *bg_ptr, bool on)
>  static u32 omap_bandgap_read_temp(struct omap_bandgap *bg_ptr, int id)
>  {

This patch is fine and it makes it cleaner than before.

But that said, I don't care for the RMW_BITS() very much as a long
term thing.  If we just used pointers instead of passing the offset
into the bg_ptr->conf->sensors[] array then everything would be a
lot cleaner.

In other words, instead of this:

static u32 omap_bandgap_read_temp(struct omap_bandgap *bg_ptr, int id)

We would have:

static u32 omap_bandgap_read_temp(struct omap_bandgap *bg_ptr,
                                  struct temp_sensor_registers *tsr)

If you have the pointer then it's easy write RMW_BITS() as a
function.

static void rmw_bits(struct omap_bandgap *bg_ptr, u32 reg, u32 mask, u32 val)
{
        u32 r;

        r = omap_bandgap_readl(bg_ptr, reg);
        r &= ~mask;
        r |= val << __ffs(mask);
        omap_bandgap_writel(bg_ptr, r, reg);
}

It's called like:

        rmw_bits(bg_ptr, tsr->bgap_mask_ctrl, tsr->mask_freeze_mask, 1);

regards,
dan carpenter


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