[PATCH 04/18] staging: typec: tcpm: Add helpers for exporting current-limit through a psy

[Hans de Goede]

Not all type-c port-controller can control the current-limit directly,
in cases where the current limit can not be controlled directly it needs
to be exported so that another driver (e.g. the charger driver) can pick
the limit up and configure the system accordingly.

The power-supply subsys already provides infrastructure for this,
power-supply devices have the notion of being supplied by another
power-supply and have properties through which we can export the
current-limit.

This commits adds 2 helper functions for use by port-controller drivers
which want to export the current-limit info in this way:

int tcpm_register_psy(struct device *dev, struct tcpc_dev *tcpc,
		      const char *name);
int tcpm_set_current_limit_psy(struct tcpc_dev *tcpc, u32 max_ma, u32 mv);

Signed-off-by: Hans de Goede <hdegoede@xxxxxxxxxx>
---
 drivers/staging/typec/tcpm-helpers.c | 66 ++++++++++++++++++++++++++++++++++++
 drivers/staging/typec/tcpm.h         |  9 +++++
 2 files changed, 75 insertions(+)

diff --git a/drivers/staging/typec/tcpm-helpers.c b/drivers/staging/typec/tcpm-helpers.c
index 0c87ec9936e1..8f7699576878 100644
--- a/drivers/staging/typec/tcpm-helpers.c
+++ b/drivers/staging/typec/tcpm-helpers.c
@@ -20,6 +20,60 @@
 
 #include "tcpm.h"
 
+static int tcpm_psy_get_property(struct power_supply *psy,
+				 enum power_supply_property psp,
+				 union power_supply_propval *val)
+{
+	struct tcpc_dev *tcpc = power_supply_get_drvdata(psy);
+
+	switch (psp) {
+	case POWER_SUPPLY_PROP_VOLTAGE_NOW:
+		val->intval = tcpc->supply_voltage * 1000; /* mV -> ÂV */
+		break;
+	case POWER_SUPPLY_PROP_CURRENT_MAX:
+		val->intval = tcpc->current_limit * 1000; /* mA -> ÂA */
+		break;
+	default:
+		return -ENODATA;
+	}
+
+	return 0;
+}
+
+static enum power_supply_property tcpm_psy_properties[] = {
+	POWER_SUPPLY_PROP_VOLTAGE_NOW,
+	POWER_SUPPLY_PROP_CURRENT_MAX,
+};
+
+int tcpm_register_psy(struct device *dev, struct tcpc_dev *tcpc,
+		      const char *name)
+{
+	struct power_supply_config psy_cfg = {};
+	struct power_supply_desc *desc;
+	int ret = 0;
+
+	desc = devm_kzalloc(dev, sizeof(*desc), GFP_KERNEL);
+	if (!desc)
+		return -ENOMEM;
+
+	desc->name		= name;
+	desc->type		= POWER_SUPPLY_TYPE_USB;
+	desc->properties	= tcpm_psy_properties;
+	desc->num_properties	= ARRAY_SIZE(tcpm_psy_properties);
+	desc->get_property	= tcpm_psy_get_property;
+	psy_cfg.drv_data	= tcpc;
+
+	tcpc->psy = devm_power_supply_register(dev, desc, &psy_cfg);
+	if (IS_ERR(tcpc->psy)) {
+		ret = PTR_ERR(tcpc->psy);
+		tcpc->psy = NULL;
+		dev_err(dev, "Error registering power-supply: %d\n", ret);
+	}
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(tcpm_register_psy);
+
 /* Generic (helper) implementations for some tcpc_dev callbacks */
 int tcpm_get_usb2_current_limit_extcon(struct tcpc_dev *tcpc)
 {
@@ -58,3 +112,15 @@ int tcpm_get_usb2_current_limit_extcon(struct tcpc_dev *tcpc)
 	return current_limit;
 }
 EXPORT_SYMBOL_GPL(tcpm_get_usb2_current_limit_extcon);
+
+int tcpm_set_current_limit_psy(struct tcpc_dev *tcpc, u32 max_ma, u32 mv)
+{
+	tcpc->supply_voltage = mv;
+	tcpc->current_limit = max_ma;
+
+	if (tcpc->psy)
+		power_supply_changed(tcpc->psy);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(tcpm_set_current_limit_psy);
diff --git a/drivers/staging/typec/tcpm.h b/drivers/staging/typec/tcpm.h
index 35e8c1e7dba0..1b1475b487b5 100644
--- a/drivers/staging/typec/tcpm.h
+++ b/drivers/staging/typec/tcpm.h
@@ -17,6 +17,7 @@
 
 #include <linux/bitops.h>
 #include <linux/extcon.h>
+#include <linux/power_supply.h>
 #include <linux/usb/typec.h>
 #include "pd.h"
 
@@ -129,6 +130,10 @@ struct tcpc_dev {
 	struct tcpc_mux_dev *mux;
 	/* Used by tcpm_get_usb2_current_limit_extcon helpers */
 	struct extcon_dev *usb2_extcon;
+	/* Used by tcpm_set_current_limit_psy helpers */
+	struct power_supply *psy;
+	u32 current_limit;
+	u32 supply_voltage;
 };
 
 struct tcpm_port;
@@ -154,7 +159,11 @@ void tcpm_pd_transmit_complete(struct tcpm_port *port,
 void tcpm_pd_hard_reset(struct tcpm_port *port);
 void tcpm_tcpc_reset(struct tcpm_port *port);
 
+int tcpm_register_psy(struct device *dev, struct tcpc_dev *tcpc,
+		      const char *name);
+
 /* Generic (helper) implementations for some tcpc_dev callbacks */
 int tcpm_get_usb2_current_limit_extcon(struct tcpc_dev *tcpc);
+int tcpm_set_current_limit_psy(struct tcpc_dev *tcpc, u32 max_ma, u32 mv);
 
 #endif /* __LINUX_USB_TCPM_H */
-- 
2.13.3