bq25710: Allow IDCHG to be used as a prochot trigger

Kohaku units are currently using a 2S+1P battery back which is not
able to provide sufficient power for peak CPU load when running on
battery only. The bq25710 has various triggers for prochot and one of
those is IDCHG (battery discharge current). This CL adds a new config
option CONFIG_CHARGER_BQ25710_IDCHG_LIMIT_MA to enable this feature in
the bq25710. For prochot to be active, the bq25710 must remain in
performance mode. Chispet hooks are used to request the bq25710 in/out
of performace mode when the IDCHG prochot feature is active.

BUG=b:132285560
BRANCH=none
TEST=Manual
Connected wires to VBAT, PPVAR_SYS, PROCHOT_ODL signals and had a
current probe connected to measure IBAT. Verfied that without this CL,
VBAT shuts off when IBAT spikes. With this CL, then verified that
prochot gets asserted whenever the current spikes to values specified
by CONFIG_CHARGER_BQ25710_IDCHG_LIMIT_MA. In addition verified that
with this CL, the system can successfully boot and remain powered on
even as CPU load gets increased.

Change-Id: If13d16f561b76289936d0d75a2b984d2b71b3c37
Signed-off-by: Scott Collyer <scollyer@google.com>
Reviewed-on: https://chromium-review.googlesource.com/1613797
Commit-Ready: Scott Collyer <scollyer@chromium.org>
Tested-by: Scott Collyer <scollyer@chromium.org>
Legacy-Commit-Queue: Commit Bot <commit-bot@chromium.org>
Reviewed-by: Tim Wawrzynczak <twawrzynczak@chromium.org>

3 files changed, 75 insertions, 0 deletions

diff --git a/driver/charger/bq25710.c b/driver/charger/bq25710.c
index 5deb59328b..5700a0325b 100644
--- a/driver/charger/bq25710.c
+++ b/driver/charger/bq25710.c
@@ -13,6 +13,7 @@
 #include "console.h"
 #include "hooks.h"
 #include "i2c.h"
+#include "task.h"
 #include "timer.h"
 
 #ifndef CONFIG_CHARGER_NARROW_VDC
@@ -35,6 +36,16 @@
 /* Console output macros */
 #define CPRINTF(format, args...) cprintf(CC_CHARGER, format, ## args)
 
+#ifdef CONFIG_CHARGER_BQ25710_IDCHG_LIMIT_MA
+/*
+ * If this config option is defined, then the bq25710 needs to remain in
+ * performance mode when the AP is in S0. Performance mode is active whenever AC
+ * power is connected or when the EN_LWPWR bit in ChargeOption0 is clear.
+ */
+static uint32_t bq25710_perf_mode_req;
+static struct mutex bq25710_perf_mode_mutex;
+#endif
+
 /* Charger parameters */
 static const struct charger_info bq25710_charger_info = {
 	.name         = "bq25710",
@@ -85,12 +96,30 @@ static int bq25710_set_low_power_mode(int enable)
 	if (rv)
 		return rv;
 
+#ifdef CONFIG_CHARGER_BQ25710_IDCHG_LIMIT_MA
+	mutex_lock(&bq25710_perf_mode_mutex);
+	/*
+	 * Performance mode means not in low power mode. The bit that controls
+	 * this is EN_LWPWR in ChargeOption0. The 'enable' param in this
+	 * function is refeerring to low power mode, so enabling low power mode
+	 * means disabling performance mode and vice versa.
+	 */
+	if (enable)
+		bq25710_perf_mode_req &= ~(1 << task_get_current());
+	else
+		bq25710_perf_mode_req |= (1 << task_get_current());
+	enable = !bq25710_perf_mode_req;
+#endif
+
 	if (enable)
 		reg |= BQ25710_CHARGE_OPTION_0_LOW_POWER_MODE;
 	else
 		reg &= ~BQ25710_CHARGE_OPTION_0_LOW_POWER_MODE;
 
 	rv = raw_write16(BQ25710_REG_CHARGE_OPTION_0, reg);
+#ifdef CONFIG_CHARGER_BQ25710_IDCHG_LIMIT_MA
+	mutex_unlock(&bq25710_perf_mode_mutex);
+#endif
 	if (rv)
 		return rv;
 
@@ -175,6 +204,21 @@ static void bq25710_init(void)
 		 * no battery is present prochot will continuosly be asserted.
 		 */
 		reg |= BQ25710_PROCHOT_PROFILE_VSYS;
+#ifdef CONFIG_CHARGER_BQ25710_IDCHG_LIMIT_MA
+		/*
+		 * Set the IDCHG limit who's value is defined in the config
+		 * option in mA. Also, enable IDCHG trigger for prochot.
+		 */
+		reg &= ~BQ25710_PROCHOT_IDCHG_VTH_MASK;
+		/*
+		 * IDCHG limit is in 512 mA steps. Note there is a 128 mA offset
+		 * so the actual IDCHG limit will be the value stored in bits
+		 * 15:10 + 128 mA.
+		 */
+		reg |= ((CONFIG_CHARGER_BQ25710_IDCHG_LIMIT_MA << 1) &
+			BQ25710_PROCHOT_IDCHG_VTH_MASK);
+		reg |= BQ25710_PROCHOT_PROFILE_IDCHG;
+#endif
 		raw_write16(BQ25710_REG_PROCHOT_OPTION_1, reg);
 	}
 
@@ -484,6 +528,25 @@ error:
 }
 #endif /* CONFIG_CHARGE_RAMP_HW */
 
+#ifdef CONFIG_CHARGER_BQ25710_IDCHG_LIMIT_MA
+/* Called on AP S5 -> S3  and S3/S0iX -> S0 transition */
+static void bq25710_chipset_startup(void)
+{
+	bq25710_set_low_power_mode(0);
+}
+DECLARE_HOOK(HOOK_CHIPSET_STARTUP, bq25710_chipset_startup, HOOK_PRIO_DEFAULT);
+DECLARE_HOOK(HOOK_CHIPSET_RESUME, bq25710_chipset_startup, HOOK_PRIO_DEFAULT);
+
+
+/* Called on AP S0 -> S0iX/S3 or S3 -> S5 transition */
+static void bq25710_chipset_suspend(void)
+{
+	bq25710_set_low_power_mode(1);
+}
+DECLARE_HOOK(HOOK_CHIPSET_SUSPEND, bq25710_chipset_suspend, HOOK_PRIO_DEFAULT);
+DECLARE_HOOK(HOOK_CHIPSET_SHUTDOWN, bq25710_chipset_suspend, HOOK_PRIO_DEFAULT);
+#endif
+
 #ifdef CONFIG_CMD_CHARGER_DUMP
 static int console_bq25710_dump_regs(int argc, char **argv)
 {
diff --git a/driver/charger/bq25710.h b/driver/charger/bq25710.h
index 3b31c88bdb..448e24bad0 100644
--- a/driver/charger/bq25710.h
+++ b/driver/charger/bq25710.h
@@ -85,6 +85,8 @@
 
 /* ProchotOption1 Register */
 #define BQ25710_PROCHOT_PROFILE_VDPM		BIT(7)
+#define BQ25710_PROCHOT_PROFILE_IDCHG		BIT(3)
 #define BQ25710_PROCHOT_PROFILE_VSYS		BIT(2)
+#define BQ25710_PROCHOT_IDCHG_VTH_MASK		0xFC00
 
 #endif /* __CROS_EC_BQ25710_H */
diff --git a/include/config.h b/include/config.h
index 5975df08a4..ca441d17cf 100644
--- a/include/config.h
+++ b/include/config.h
@@ -817,6 +817,16 @@
  */
 #undef CONFIG_CHARGER_INPUT_CURRENT
 
+/*
+ * This config option is used to enable IDCHG trigger for prochot. This macro
+ * should be set to the desired current limit to draw from the battery before
+ * triggering prochot. Note that is has a 512 mA granularity. The function that
+ * sets the limit will mask of the lower 10 bits. For this check to be active
+ * the bq25710 must be in performance mode and this config option is also used
+ * to keep the bq25710 in performance mode when the AP is in S0.
+ */
+#undef CONFIG_CHARGER_BQ25710_IDCHG_LIMIT_MA
+
 /* Define to use Power Delivery State Machine Framework */
 #undef CONFIG_USB_SM_FRAMEWORK