Let AP read sensor IDs when DPTF thermal thresholds crossed

The spec does not mandate any way to read back the threshold settings
themselves, but when a threshold is crossed the AP needs a way to determine
which sensor(s) are responsible. Each reading of the EC_ACPI_MEM_TEMP_ID
register clears and returns one sensor ID that has crossed one of its
thresholds (in either direction) since the last read. A value of 0xFF means
"no new thresholds have tripped". Changing or enabling the thresholds for
any sensor will clear the unread event count for that sensor.

BUG=chrome-os-partner:23970
BRANCH=none
TEST=manual

On the host, set a couple of thresholds to low values so they trip
immediately (I'm testing on Link):

  # dptf() {
         [ "$#" -eq "2" ] || return;
         iotools io_write8 0x66 0x81
         iotools io_write8 0x62 $1
         iotools io_write8 0x62 $2
  }
  #

  # dptf 5 0
  # dptf 6 10
  # dptf 7 3

  # dptf 5 2
  # dptf 6 10
  # dptf 7 2

On the EC console, see that two thresholds have triggered, and that there
are two bits set in the AP seen mask:

  [45.755365 DPTF sensor 0, threshold -63 C, index 1, enabled]
  [45.768940 DPTF sensor 2, threshold -63 C, index 0, enabled]
  [46.169490 DPTF over threshold [0][1]
  [46.169820 DPTF over threshold [2][0]
  > dptftemp
  sensor   thresh0   thresh1
    0       ---        210*    I2C-USB C-Die
    1       ---        ---     I2C-USB C-Object
    2       210*       ---     I2C-PCH D-Die
    3       ---        ---     I2C-PCH D-Object
    4       ---        ---     I2C-Hinge C-Die
    5       ---        ---     I2C-Hinge C-Object
    6       ---        ---     I2C-Charger D-Die
    7       ---        ---     I2C-Charger D-Object
    8       ---        ---     ECInternal
    9       ---        ---     PECI
  AP seen mask: 0x00000005
  >

Read the EC_ACPI_MEM_TEMP_ID register from the host, to get the two active
sensor IDs (0 and 2), then 0xff when those are seen.

  # iotools io_write8 0x66 0x80; iotools io_write8 0x62 5; iotools io_read8 0x62
  0x00
  # iotools io_write8 0x66 0x80; iotools io_write8 0x62 5; iotools io_read8 0x62
  0x02
  # iotools io_write8 0x66 0x80; iotools io_write8 0x62 5; iotools io_read8 0x62
  0xff
  # iotools io_write8 0x66 0x80; iotools io_write8 0x62 5; iotools io_read8 0x62
  0xff
  #

Change-Id: I8f047a517357617f18ad59d21fa13409bc81821b
Signed-off-by: Bill Richardson <wfrichar@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/180224
Reviewed-by: Randall Spangler <rspangler@chromium.org>

4 files changed, 37 insertions, 5 deletions

diff --git a/common/acpi.c b/common/acpi.c
index 68c281b6e6..69cf3bc837 100644
--- a/common/acpi.c
+++ b/common/acpi.c
@@ -71,6 +71,11 @@ int acpi_ap_to_ec(int is_cmd, uint8_t value, uint8_t *resultptr)
 			result = dptf_get_fan_duty_target();
 			break;
 #endif
+#ifdef CONFIG_TEMP_SENSOR
+		case EC_ACPI_MEM_TEMP_ID:
+			result = dptf_query_next_sensor_event();
+			break;
+#endif
 		default:
 			CPRINTF("[%T ACPI read 0x%02x (ignored)]\n", acpi_addr);
 			break;
diff --git a/common/thermal.c b/common/thermal.c
index 6464ef7161..7113564f82 100644
--- a/common/thermal.c
+++ b/common/thermal.c
@@ -7,6 +7,7 @@
  * implementation from the original version that shipped on Link.
  */
 
+#include "atomic.h"
 #include "chipset.h"
 #include "common.h"
 #include "console.h"
@@ -45,8 +46,21 @@ static void dptf_init(void)
 }
 DECLARE_HOOK(HOOK_INIT, dptf_init, HOOK_PRIO_DEFAULT);
 
+/* Keep track of which triggered sensor thresholds the AP has seen */
+static uint32_t dptf_seen;
 
+int dptf_query_next_sensor_event(void)
+{
+	int id;
 
+	for (id = 0; id < TEMP_SENSOR_COUNT; id++)
+		if (dptf_seen & (1 << id)) {	/* atomic? */
+			atomic_clear(&dptf_seen, (1 << id));
+			return id;
+		}
+
+	return -1;
+}
 
 /* Return true if any threshold transition occurs. */
 static int dpft_check_temp_threshold(int sensor_id, int temp)
@@ -68,11 +82,13 @@ static int dpft_check_temp_threshold(int sensor_id, int temp)
 		if (cond_went_true(&dptf_threshold[sensor_id][i].over)) {
 			CPRINTF("[%T DPTF over threshold [%d][%d]\n",
 				sensor_id, i);
+			atomic_or(&dptf_seen, (1 << sensor_id));
 			tripped = 1;
 		}
 		if (cond_went_false(&dptf_threshold[sensor_id][i].over)) {
 			CPRINTF("[%T DPTF under threshold [%d][%d]\n",
 				sensor_id, i);
+			atomic_or(&dptf_seen, (1 << sensor_id));
 			tripped = 1;
 		}
 	}
@@ -80,7 +96,6 @@ static int dpft_check_temp_threshold(int sensor_id, int temp)
 	return tripped;
 }
 
-
 void dptf_set_temp_threshold(int sensor_id, int temp, int idx, int enable)
 {
 	CPRINTF("[%T DPTF sensor %d, threshold %d C, index %d, %sabled]\n",
@@ -89,15 +104,12 @@ void dptf_set_temp_threshold(int sensor_id, int temp, int idx, int enable)
 	if (enable) {
 		dptf_threshold[sensor_id][idx].temp = temp;
 		cond_init(&dptf_threshold[sensor_id][idx].over, 0);
+		atomic_clear(&dptf_seen, (1 << sensor_id));
 	} else {
 		dptf_threshold[sensor_id][idx].temp = -1;
 	}
 }
 
-
-
-
-
 /*****************************************************************************/
 /* EC-specific thermal controls */
 
@@ -350,6 +362,7 @@ static int command_dptftemp(int argc, char **argv)
 		ccprintf("    %s\n", temp_sensors[id].name);
 	}
 
+	ccprintf("AP seen mask: 0x%08x\n", dptf_seen);
 	return EC_SUCCESS;
 }
 DECLARE_CONSOLE_COMMAND(dptftemp, command_dptftemp,
diff --git a/include/dptf.h b/include/dptf.h
index 31c9c09bca..f611acb361 100644
--- a/include/dptf.h
+++ b/include/dptf.h
@@ -24,4 +24,10 @@ void dptf_set_temp_threshold(int sensor_id,	/* zero-based sensor index */
 			     int idx,		/* which threshold (0 or 1) */
 			     int enable);	/* true = on, false = off */
 
+/*
+ * Return the ID of a temp sensor that has crossed its threshold since the last
+   time we asked. -1 means none.
+ */
+int dptf_query_next_sensor_event(void);
+
 #endif	/* __CROS_EC_DPTF_H */
diff --git a/include/ec_commands.h b/include/ec_commands.h
index 7b3fb170d1..f526accd00 100644
--- a/include/ec_commands.h
+++ b/include/ec_commands.h
@@ -1877,6 +1877,14 @@ struct ec_params_reboot_ec {
  * register determines which sensor is affected by the THRESHOLD and COMMIT
  * registers. The THRESHOLD register uses the same EC_TEMP_SENSOR_OFFSET scheme
  * as the memory-mapped sensors. The COMMIT register applies those settings.
+ *
+ * The spec does not mandate any way to read back the threshold settings
+ * themselves, but when a threshold is crossed the AP needs a way to determine
+ * which sensor(s) are responsible. Each reading of the ID register clears and
+ * returns one sensor ID that has crossed one of its threshold (in either
+ * direction) since the last read. A value of 0xFF means "no new thresholds
+ * have tripped". Setting or enabling the thresholds for a sensor will clear
+ * the unread event count for that sensor.
  */
 #define EC_ACPI_MEM_TEMP_ID            0x05
 #define EC_ACPI_MEM_TEMP_THRESHOLD     0x06