[PATCH 2/2] thermal: ti-soc-thermal: OMAP5: Implement Workaround for Errata i813

[Keerthy <j-keerthy@ti.com>]

DESCRIPTION

Spurious Thermal Alert: Talert can happen randomly while the device remains under the temperature limit
defined for this event to trig. This spurious event is caused by a incorrect re-synchronization between
clock domains. The comparison between configured threshold and current temperature value can happen
while the value is transitioning (metastable), thus causing inappropriate event generation.
No spurious event occurs as long as the threshold value stays unchanged. Spurious event can be
generated while a thermal alert threshold is modified in
CONTROL_BANDGAP_THRESHOLD_MPU/GPU/CORE/DSPEVE/IVA_n.
WORKAROUND

Spurious event generation can be avoided by performing following sequence when the threshold is
modified:
1. Mask the hot/cold events at the thermal IP level.
2. Modify Threshold.
3. Unmask the hot/cold events at the thermal IP level.

Signed-off-by: Keerthy <j-keerthy@ti.com>
---
 .../thermal/ti-soc-thermal/omap5-thermal-data.c    |  3 +-
 drivers/thermal/ti-soc-thermal/ti-bandgap.c        | 41 +++++++++++++++++++++-
 drivers/thermal/ti-soc-thermal/ti-bandgap.h        |  4 ++-
 3 files changed, 45 insertions(+), 3 deletions(-)

diff --git a/drivers/thermal/ti-soc-thermal/omap5-thermal-data.c b/drivers/thermal/ti-soc-thermal/omap5-thermal-data.c
index eff0c80..79ff70c 100644
--- a/drivers/thermal/ti-soc-thermal/omap5-thermal-data.c
+++ b/drivers/thermal/ti-soc-thermal/omap5-thermal-data.c
@@ -319,7 +319,8 @@ const struct ti_bandgap_data omap5430_data = {
 			TI_BANDGAP_FEATURE_FREEZE_BIT |
 			TI_BANDGAP_FEATURE_TALERT |
 			TI_BANDGAP_FEATURE_COUNTER_DELAY |
-			TI_BANDGAP_FEATURE_HISTORY_BUFFER,
+			TI_BANDGAP_FEATURE_HISTORY_BUFFER |
+			TI_BANDGAP_FEATURE_ERRATA_813,
 	.fclock_name = "l3instr_ts_gclk_div",
 	.div_ck_name = "l3instr_ts_gclk_div",
 	.conv_table = omap5430_adc_to_temp,
diff --git a/drivers/thermal/ti-soc-thermal/ti-bandgap.c b/drivers/thermal/ti-soc-thermal/ti-bandgap.c
index 8fdddb6..08a2155 100644
--- a/drivers/thermal/ti-soc-thermal/ti-bandgap.c
+++ b/drivers/thermal/ti-soc-thermal/ti-bandgap.c
@@ -445,7 +445,7 @@ static int ti_bandgap_update_alert_threshold(struct ti_bandgap *bgp, int id,
 {
 	struct temp_sensor_data *ts_data = bgp->conf->sensors[id].ts_data;
 	struct temp_sensor_registers *tsr;
-	u32 thresh_val, reg_val, t_hot, t_cold;
+	u32 thresh_val, reg_val, t_hot, t_cold, ctrl;
 	int err = 0;
 
 	tsr = bgp->conf->sensors[id].registers;
@@ -477,8 +477,47 @@ static int ti_bandgap_update_alert_threshold(struct ti_bandgap *bgp, int id,
 		  ~(tsr->threshold_thot_mask | tsr->threshold_tcold_mask);
 	reg_val |= (t_hot << __ffs(tsr->threshold_thot_mask)) |
 		   (t_cold << __ffs(tsr->threshold_tcold_mask));
+
+	/**
+	 * Errata i813:
+	 * Spurious Thermal Alert: Talert can happen randomly while the device
+	 * remains under the temperature limit defined for this event to trig.
+	 * This spurious event is caused by a incorrect re-synchronization
+	 * between clock domains. The comparison between configured threshold
+	 * and current temperature value can happen while the value is
+	 * transitioning (metastable), thus causing inappropriate event
+	 * generation. No spurious event occurs as long as the threshold value
+	 * stays unchanged. Spurious event can be generated while a thermal
+	 * alert threshold is modified in
+	 * CONTROL_BANDGAP_THRESHOLD_MPU/GPU/CORE/DSPEVE/IVA_n.
+	 */
+
+	if (TI_BANDGAP_HAS(bgp, ERRATA_813)) {
+		/* Mask t_hot and t_cold events at the IP Level */
+		ctrl = ti_bandgap_readl(bgp, tsr->bgap_mask_ctrl);
+
+		if (hot)
+			ctrl &= ~tsr->mask_hot_mask;
+		else
+			ctrl &= ~tsr->mask_cold_mask;
+
+		ti_bandgap_writel(bgp, ctrl, tsr->bgap_mask_ctrl);
+	}
+
+	/* Write the threshold value */
 	ti_bandgap_writel(bgp, reg_val, tsr->bgap_threshold);
 
+	if (TI_BANDGAP_HAS(bgp, ERRATA_813)) {
+		/* Unmask t_hot and t_cold events at the IP Level */
+		ctrl = ti_bandgap_readl(bgp, tsr->bgap_mask_ctrl);
+		if (hot)
+			ctrl |= tsr->mask_hot_mask;
+		else
+			ctrl |= tsr->mask_cold_mask;
+
+		ti_bandgap_writel(bgp, ctrl, tsr->bgap_mask_ctrl);
+	}
+
 	if (err) {
 		dev_err(bgp->dev, "failed to reprogram thot threshold\n");
 		err = -EIO;
diff --git a/drivers/thermal/ti-soc-thermal/ti-bandgap.h b/drivers/thermal/ti-soc-thermal/ti-bandgap.h
index b2da3fc..0c52f7a 100644
--- a/drivers/thermal/ti-soc-thermal/ti-bandgap.h
+++ b/drivers/thermal/ti-soc-thermal/ti-bandgap.h
@@ -320,7 +320,8 @@ struct ti_temp_sensor {
  *
  * TI_BANDGAP_FEATURE_ERRATA_814 - used to workaorund when the bandgap device
  *	has Errata 814
- *
+ * TI_BANDGAP_FEATURE_ERRATA_813 - used to workaorund when the bandgap device
+ *	has Errata 813
  * TI_BANDGAP_HAS(b, f) - macro to check if a bandgap device is capable of a
  *      specific feature (above) or not. Return non-zero, if yes.
  */
@@ -335,6 +336,7 @@ struct ti_temp_sensor {
 #define TI_BANDGAP_FEATURE_COUNTER_DELAY	BIT(8)
 #define TI_BANDGAP_FEATURE_HISTORY_BUFFER	BIT(9)
 #define TI_BANDGAP_FEATURE_ERRATA_814		BIT(10)
+#define TI_BANDGAP_FEATURE_ERRATA_813		BIT(11)
 #define TI_BANDGAP_HAS(b, f)			\
 			((b)->conf->features & TI_BANDGAP_FEATURE_ ## f)
 
-- 
1.9.1