thermal: rcar_gen3_thermal: Read calibration from hardware

In production hardware the calibration values used to convert register
values to temperatures can be read from hardware. While pre-production
hardware still depends on pseudo values hard-coded in the driver.

Add support for reading out calibration values from hardware if it's
fused. The presence of fused calibration is indicated in the THSCP
register.

Signed-off-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
Tested-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/20211014103816.1939782-3-niklas.soderlund+renesas@ragnatech.se
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>

diff --git a/drivers/thermal/rcar_gen3_thermal.c b/drivers/thermal/rcar_gen3_thermal.c
index 7d7e6eb..43eb25b 100644 (file)
--- a/drivers/thermal/rcar_gen3_thermal.c
+++ b/drivers/thermal/rcar_gen3_thermal.c
@@ -34,6 +34,10 @@
 #define REG_GEN3_THCODE1       0x50
 #define REG_GEN3_THCODE2       0x54
 #define REG_GEN3_THCODE3       0x58
+#define REG_GEN3_PTAT1         0x5c
+#define REG_GEN3_PTAT2         0x60
+#define REG_GEN3_PTAT3         0x64
+#define REG_GEN3_THSCP         0x68
 
 /* IRQ{STR,MSK,EN} bits */
 #define IRQ_TEMP1              BIT(0)
@@ -55,6 +59,9 @@
 #define THCTR_PONM     BIT(6)
 #define THCTR_THSST    BIT(0)
 
+/* THSCP bits */
+#define THSCP_COR_PARA_VLD     (BIT(15) | BIT(14))
+
 #define CTEMP_MASK     0xFFF
 
 #define MCELSIUS(temp) ((temp) * 1000)
@@ -245,6 +252,64 @@ static const struct soc_device_attribute r8a7795es1[] = {
        { /* sentinel */ }
 };
 
+static bool rcar_gen3_thermal_read_fuses(struct rcar_gen3_thermal_priv *priv)
+{
+       unsigned int i;
+       u32 thscp;
+
+       /* If fuses are not set, fallback to pseudo values. */
+       thscp = rcar_gen3_thermal_read(priv->tscs[0], REG_GEN3_THSCP);
+       if ((thscp & THSCP_COR_PARA_VLD) != THSCP_COR_PARA_VLD) {
+               /* Default THCODE values in case FUSEs are not set. */
+               static const int thcodes[TSC_MAX_NUM][3] = {
+                       { 3397, 2800, 2221 },
+                       { 3393, 2795, 2216 },
+                       { 3389, 2805, 2237 },
+                       { 3415, 2694, 2195 },
+                       { 3356, 2724, 2244 },
+               };
+
+               priv->ptat[0] = 2631;
+               priv->ptat[1] = 1509;
+               priv->ptat[2] = 435;
+
+               for (i = 0; i < priv->num_tscs; i++) {
+                       struct rcar_gen3_thermal_tsc *tsc = priv->tscs[i];
+
+                       tsc->thcode[0] = thcodes[i][0];
+                       tsc->thcode[1] = thcodes[i][1];
+                       tsc->thcode[2] = thcodes[i][2];
+               }
+
+               return false;
+       }
+
+       /*
+        * Set the pseudo calibration points with fused values.
+        * PTAT is shared between all TSCs but only fused for the first
+        * TSC while THCODEs are fused for each TSC.
+        */
+       priv->ptat[0] = rcar_gen3_thermal_read(priv->tscs[0], REG_GEN3_PTAT1) &
+               GEN3_FUSE_MASK;
+       priv->ptat[1] = rcar_gen3_thermal_read(priv->tscs[0], REG_GEN3_PTAT2) &
+               GEN3_FUSE_MASK;
+       priv->ptat[2] = rcar_gen3_thermal_read(priv->tscs[0], REG_GEN3_PTAT3) &
+               GEN3_FUSE_MASK;
+
+       for (i = 0; i < priv->num_tscs; i++) {
+               struct rcar_gen3_thermal_tsc *tsc = priv->tscs[i];
+
+               tsc->thcode[0] = rcar_gen3_thermal_read(tsc, REG_GEN3_THCODE1) &
+                       GEN3_FUSE_MASK;
+               tsc->thcode[1] = rcar_gen3_thermal_read(tsc, REG_GEN3_THCODE2) &
+                       GEN3_FUSE_MASK;
+               tsc->thcode[2] = rcar_gen3_thermal_read(tsc, REG_GEN3_THCODE3) &
+                       GEN3_FUSE_MASK;
+       }
+
+       return true;
+}
+
 static void rcar_gen3_thermal_init_r8a7795es1(struct rcar_gen3_thermal_tsc *tsc)
 {
        rcar_gen3_thermal_write(tsc, REG_GEN3_CTSR,  CTSR_THBGR);
@@ -393,16 +458,6 @@ static int rcar_gen3_thermal_probe(struct platform_device *pdev)
        unsigned int i;
        int ret;
 
-       /* Default THCODE values in case FUSEs are not set. */
-       /* TODO: Read values from hardware on supported platforms */
-       static const int thcodes[TSC_MAX_NUM][3] = {
-               { 3397, 2800, 2221 },
-               { 3393, 2795, 2216 },
-               { 3389, 2805, 2237 },
-               { 3415, 2694, 2195 },
-               { 3356, 2724, 2244 },
-       };
-
        priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
        if (!priv)
                return -ENOMEM;
@@ -411,10 +466,6 @@ static int rcar_gen3_thermal_probe(struct platform_device *pdev)
        if (soc_device_match(r8a7795es1))
                priv->thermal_init = rcar_gen3_thermal_init_r8a7795es1;
 
-       priv->ptat[0] = 2631;
-       priv->ptat[1] = 1509;
-       priv->ptat[2] = 435;
-
        platform_set_drvdata(pdev, priv);
 
        if (rcar_gen3_thermal_request_irqs(priv, pdev))
@@ -442,11 +493,16 @@ static int rcar_gen3_thermal_probe(struct platform_device *pdev)
                        goto error_unregister;
                }
 
-               tsc->thcode[0] = thcodes[i][0];
-               tsc->thcode[1] = thcodes[i][1];
-               tsc->thcode[2] = thcodes[i][2];
-
                priv->tscs[i] = tsc;
+       }
+
+       priv->num_tscs = i;
+
+       if (!rcar_gen3_thermal_read_fuses(priv))
+               dev_info(dev, "No calibration values fused, fallback to driver values\n");
+
+       for (i = 0; i < priv->num_tscs; i++) {
+               struct rcar_gen3_thermal_tsc *tsc = priv->tscs[i];
 
                zone = devm_thermal_zone_of_sensor_register(dev, i, tsc,
                                                            &rcar_gen3_tz_of_ops);
@@ -476,8 +532,6 @@ static int rcar_gen3_thermal_probe(struct platform_device *pdev)
                dev_info(dev, "TSC%u: Loaded %d trip points\n", i, ret);
        }
 
-       priv->num_tscs = i;
-
        if (!priv->num_tscs) {
                ret = -ENODEV;
                goto error_unregister;