[PATCH 5.12 271/292] thermal/drivers/rcar_gen3_thermal: Fix coefficient calculations

[Greg Kroah-Hartman]

From: Niklas Söderlund <niklas.soderlund+renesas@xxxxxxxxxxxx>

[ Upstream commit 8946187ab57ffd02088e50256c73dd31f49db06d ]

The fixed value of 157 used in the calculations are only correct for
M3-W, on other Gen3 SoC it should be 167. The constant can be derived
correctly from the static TJ_3 constant and the SoC specific TJ_1 value.
Update the calculation be correct on all Gen3 SoCs.

Fixes: 4eb39f79ef44 ("thermal: rcar_gen3_thermal: Update value of Tj_1")
Reported-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@xxxxxxxxxxx>
Signed-off-by: Niklas Söderlund <niklas.soderlund+renesas@xxxxxxxxxxxx>
Reviewed-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@xxxxxxxxxxx>
Reviewed-by: Geert Uytterhoeven <geert+renesas@xxxxxxxxx>
Signed-off-by: Daniel Lezcano <daniel.lezcano@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20210605085211.564909-1-niklas.soderlund+renesas@xxxxxxxxxxxx
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 drivers/thermal/rcar_gen3_thermal.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/thermal/rcar_gen3_thermal.c b/drivers/thermal/rcar_gen3_thermal.c
index 75c69fe6e955..c02922d2d1d5 100644
--- a/drivers/thermal/rcar_gen3_thermal.c
+++ b/drivers/thermal/rcar_gen3_thermal.c
@@ -142,7 +142,7 @@ static void rcar_gen3_thermal_calc_coefs(struct rcar_gen3_thermal_tsc *tsc,
 	 * Division is not scaled in BSP and if scaled it might overflow
 	 * the dividend (4095 * 4095 << 14 > INT_MAX) so keep it unscaled
 	 */
-	tsc->tj_t = (FIXPT_INT((ptat[1] - ptat[2]) * 157)
+	tsc->tj_t = (FIXPT_INT((ptat[1] - ptat[2]) * (ths_tj_1 - TJ_3))
 		     / (ptat[0] - ptat[2])) + FIXPT_INT(TJ_3);
 
 	tsc->coef.a1 = FIXPT_DIV(FIXPT_INT(thcode[1] - thcode[2]),
-- 
2.30.2