diff --git a/drivers/thermal/rcar_gen3_thermal.c b/drivers/thermal/rcar_gen3_thermal.c index 7c1ca912b9b1..02494fa142c3 100644 --- a/drivers/thermal/rcar_gen3_thermal.c +++ b/drivers/thermal/rcar_gen3_thermal.c @@ -65,26 +65,29 @@ #define TSC_MAX_NUM 5 -/* Structure for thermal temperature calculation */ -struct equation_coefs { - int a1; - int b1; - int a2; - int b2; -}; - struct rcar_gen3_thermal_priv; struct rcar_thermal_info { - int ths_tj_1; + int scale; + int adj_below; + int adj_above; void (*read_fuses)(struct rcar_gen3_thermal_priv *priv); }; +struct equation_set_coef { + int a; + int b; +}; + struct rcar_gen3_thermal_tsc { struct rcar_gen3_thermal_priv *priv; void __iomem *base; struct thermal_zone_device *zone; - struct equation_coefs coef; + /* Different coefficients are used depending on a threshold. */ + struct { + struct equation_set_coef below; + struct equation_set_coef above; + } coef; int thcode[3]; }; @@ -112,90 +115,75 @@ static inline void rcar_gen3_thermal_write(struct rcar_gen3_thermal_tsc *tsc, /* * Linear approximation for temperature * - * [reg] = [temp] * a + b => [temp] = ([reg] - b) / a + * [temp] = ((thadj - [reg]) * a) / b + adj + * [reg] = thadj - ([temp] - adj) * b / a * * The constants a and b are calculated using two triplets of int values PTAT * and THCODE. PTAT and THCODE can either be read from hardware or use hard - * coded values from driver. The formula to calculate a and b are taken from - * BSP and sparsely documented and understood. + * coded values from the driver. The formula to calculate a and b are taken from + * the datasheet. Different calculations are needed for a and b depending on + * if the input variables ([temp] or [reg]) are above or below a threshold. The + * threshold is also calculated from PTAT and THCODE using formulas from the + * datasheet. * - * Examining the linear formula and the formula used to calculate constants a - * and b while knowing that the span for PTAT and THCODE values are between - * 0x000 and 0xfff the largest integer possible is 0xfff * 0xfff == 0xffe001. - * Integer also needs to be signed so that leaves 7 bits for binary - * fixed point scaling. + * The constant thadj is one of the THCODE values, which one to use depends on + * the threshold and input value. + * + * The constants adj is taken verbatim from the datasheet. Two values exists, + * which one to use depends on the input value and the calculated threshold. + * Furthermore different SoC models supported by the driver have different sets + * of values. The values for each model are stored in the device match data. */ -#define FIXPT_SHIFT 7 -#define FIXPT_INT(_x) ((_x) << FIXPT_SHIFT) -#define INT_FIXPT(_x) ((_x) >> FIXPT_SHIFT) -#define FIXPT_DIV(_a, _b) DIV_ROUND_CLOSEST(((_a) << FIXPT_SHIFT), (_b)) -#define FIXPT_TO_MCELSIUS(_x) ((_x) * 1000 >> FIXPT_SHIFT) - -#define RCAR3_THERMAL_GRAN 500 /* mili Celsius */ - -/* no idea where these constants come from */ -#define TJ_3 -41 - static void rcar_gen3_thermal_shared_coefs(struct rcar_gen3_thermal_priv *priv) { - int tj1 = priv->info->ths_tj_1; - - priv->tj_t = (FIXPT_INT((priv->ptat[1] - priv->ptat[2]) * (tj1 - TJ_3)) - / (priv->ptat[0] - priv->ptat[2])) + FIXPT_INT(TJ_3); + priv->tj_t = + DIV_ROUND_CLOSEST((priv->ptat[1] - priv->ptat[2]) * priv->info->scale, + priv->ptat[0] - priv->ptat[2]) + + priv->info->adj_below; } - static void rcar_gen3_thermal_tsc_coefs(struct rcar_gen3_thermal_priv *priv, struct rcar_gen3_thermal_tsc *tsc) { - int tj1 = priv->info->ths_tj_1; + tsc->coef.below.a = priv->info->scale * (priv->ptat[2] - priv->ptat[1]); + tsc->coef.above.a = priv->info->scale * (priv->ptat[0] - priv->ptat[1]); - /* TODO: Find documentation and document constant calculation formula */ - - /* - * Division is not scaled in BSP and if scaled it might overflow - * the dividend (4095 * 4095 << 14 > INT_MAX) so keep it unscaled - */ - tsc->coef.a1 = FIXPT_DIV(FIXPT_INT(tsc->thcode[1] - tsc->thcode[2]), - priv->tj_t - FIXPT_INT(TJ_3)); - tsc->coef.b1 = FIXPT_INT(tsc->thcode[2]) - tsc->coef.a1 * TJ_3; - - tsc->coef.a2 = FIXPT_DIV(FIXPT_INT(tsc->thcode[1] - tsc->thcode[0]), - priv->tj_t - FIXPT_INT(tj1)); - tsc->coef.b2 = FIXPT_INT(tsc->thcode[0]) - tsc->coef.a2 * tj1; -} - -static int rcar_gen3_thermal_round(int temp) -{ - int result, round_offs; - - round_offs = temp >= 0 ? RCAR3_THERMAL_GRAN / 2 : - -RCAR3_THERMAL_GRAN / 2; - result = (temp + round_offs) / RCAR3_THERMAL_GRAN; - return result * RCAR3_THERMAL_GRAN; + tsc->coef.below.b = (priv->ptat[2] - priv->ptat[0]) * (tsc->thcode[2] - tsc->thcode[1]); + tsc->coef.above.b = (priv->ptat[0] - priv->ptat[2]) * (tsc->thcode[1] - tsc->thcode[0]); } static int rcar_gen3_thermal_get_temp(struct thermal_zone_device *tz, int *temp) { struct rcar_gen3_thermal_tsc *tsc = thermal_zone_device_priv(tz); - int mcelsius, val; - int reg; + struct rcar_gen3_thermal_priv *priv = tsc->priv; + const struct equation_set_coef *coef; + int adj, decicelsius, reg, thcode; /* Read register and convert to mili Celsius */ reg = rcar_gen3_thermal_read(tsc, REG_GEN3_TEMP) & CTEMP_MASK; - if (reg <= tsc->thcode[1]) - val = FIXPT_DIV(FIXPT_INT(reg) - tsc->coef.b1, - tsc->coef.a1); - else - val = FIXPT_DIV(FIXPT_INT(reg) - tsc->coef.b2, - tsc->coef.a2); - mcelsius = FIXPT_TO_MCELSIUS(val); + if (reg < tsc->thcode[1]) { + adj = priv->info->adj_below; + coef = &tsc->coef.below; + thcode = tsc->thcode[2]; + } else { + adj = priv->info->adj_above; + coef = &tsc->coef.above; + thcode = tsc->thcode[0]; + } + + /* + * The dividend can't be grown as it might overflow, instead shorten the + * divisor to convert to decidegree Celsius. If we convert after the + * division precision is lost as we will scale up from whole degrees + * Celsius. + */ + decicelsius = DIV_ROUND_CLOSEST(coef->a * (thcode - reg), coef->b / 10); /* Guaranteed operating range is -40C to 125C. */ - /* Round value to device granularity setting */ - *temp = rcar_gen3_thermal_round(mcelsius); + /* Reporting is done in millidegree Celsius */ + *temp = decicelsius * 100 + adj * 1000; return 0; } @@ -204,15 +192,21 @@ static int rcar_gen3_thermal_mcelsius_to_temp(struct rcar_gen3_thermal_tsc *tsc, int mcelsius) { struct rcar_gen3_thermal_priv *priv = tsc->priv; - int celsius, val; + const struct equation_set_coef *coef; + int adj, celsius, thcode; celsius = DIV_ROUND_CLOSEST(mcelsius, 1000); - if (celsius <= INT_FIXPT(priv->tj_t)) - val = celsius * tsc->coef.a1 + tsc->coef.b1; - else - val = celsius * tsc->coef.a2 + tsc->coef.b2; + if (celsius < priv->tj_t) { + coef = &tsc->coef.below; + adj = priv->info->adj_below; + thcode = tsc->thcode[2]; + } else { + coef = &tsc->coef.above; + adj = priv->info->adj_above; + thcode = tsc->thcode[0]; + } - return INT_FIXPT(val); + return thcode - DIV_ROUND_CLOSEST((celsius - adj) * coef->b, coef->a); } static int rcar_gen3_thermal_set_trips(struct thermal_zone_device *tz, int low, int high) @@ -377,17 +371,23 @@ static void rcar_gen3_thermal_init(struct rcar_gen3_thermal_priv *priv, } static const struct rcar_thermal_info rcar_m3w_thermal_info = { - .ths_tj_1 = 116, + .scale = 157, + .adj_below = -41, + .adj_above = 116, .read_fuses = rcar_gen3_thermal_read_fuses_gen3, }; static const struct rcar_thermal_info rcar_gen3_thermal_info = { - .ths_tj_1 = 126, + .scale = 167, + .adj_below = -41, + .adj_above = 126, .read_fuses = rcar_gen3_thermal_read_fuses_gen3, }; static const struct rcar_thermal_info rcar_gen4_thermal_info = { - .ths_tj_1 = 126, + .scale = 167, + .adj_below = -41, + .adj_above = 126, .read_fuses = rcar_gen3_thermal_read_fuses_gen4, };