On Tue, 10 Jul 2012 11:59:42 +0900
Kuninori Morimoto <kuninori.morimoto...@renesas.com> wrote:
> This patch add basic Renesas R-Car thermal sensor support.
> It was tested on R-Car H1 Marzen board.
>
> ...
>
> +static void rcar_thermal_bset(struct rcar_thermal_priv *priv, u32 reg,
> + u32 mask, u32 data)
> +{
> + u32 val = rcar_thermal_read(priv, reg);
> +
> + val &= ~mask;
> + val |= (data & mask);
> +
> + rcar_thermal_write(priv, reg, val);
> +}
The driver generally looks terribly racy on SMP or uniprocessor with
preemption.
> +/*
> + * zone device functions
> + */
> +static int rcar_thermal_get_temp(struct thermal_zone_device *zone,
> + unsigned long *temp)
> +{
> + struct rcar_thermal_priv *priv = zone->devdata;
> + int val, min, max, tmp;
> +
> + tmp = -200; /* default */
> + while (1) {
> + if (priv->comp < 1 || priv->comp > 12) {
> + dev_err(priv->dev,
> + "THSSR invalid data (%d)\n", priv->comp);
> + priv->comp = 4; /* for next thermal */
> + return -EINVAL;
> + }
> +
> + /*
> + * THS comparator offset and the reference temperature
> + *
> + * Comparator | reference | Temperature field
> + * offset | temperature | measurement
> + * | (degrees C) | (degrees C)
> + * -------------+---------------+-------------------
> + * 1 | -45 | -45 to -30
> + * 2 | -30 | -30 to -15
> + * 3 | -15 | -15 to 0
> + * 4 | 0 | 0 to +15
> + * 5 | +15 | +15 to +30
> + * 6 | +30 | +30 to +45
> + * 7 | +45 | +45 to +60
> + * 8 | +60 | +60 to +75
> + * 9 | +75 | +75 to +90
> + * 10 | +90 | +90 to +105
> + * 11 | +105 | +105 to +120
> + * 12 | +120 | +120 to +135
> + */
> +
> + rcar_thermal_bset(priv, THSCR, CPTAP, priv->comp);
> + udelay(300);
Please try to avoid bare a udelay() like this. It is very hard for the
reader to understand why the delay is in there, and why it has tahe
particular duration So a comment explaining the reasons is often
beneficial.
> + /*
> + * calculate thermal limitation.
> + * see above "Temperature field measurement"
> + */
> + min = (priv->comp * 15) - 60;
> + max = min + 15;
> +
> + /*
> + * get current temperature,
> + */
> + val = rcar_thermal_read(priv, THSSR) & CTEMP;
> + val = (val * 5) - 65;
> +
> + dev_dbg(priv->dev, "comp/min/max/val = %d/%d/%d/%d\n",
> + priv->comp, min, max, val);
> +
> + /*
> + * If val is same as min/max, then,
> + * it should try again on next comparator.
> + * But the val might be correct temperature.
> + * Keep it on "tmp" and compare with next val.
> + */
> + if (val <= min) {
> + if (tmp == min)
> + break;
> +
> + tmp = min;
> + priv->comp--; /* try again */
> + } else if (val >= max) {
> + if (tmp == max)
> + break;
> +
> + tmp = max;
> + priv->comp++; /* try again */
> + } else {
> + tmp = val;
> + break;
> + }
> + }
> +
> + *temp = tmp;
> + return 0;
> +}
>
> ...
>
> + priv->comp = 4; /* basic setup */
> + priv->dev = &pdev->dev;
> +
> + priv->base = devm_ioremap_nocache(&pdev->dev,
> + res->start, resource_size(res));
A single space before the "=" is conventional.
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