On 08/30/2017 02:48 AM, Hans de Goede wrote:
The fusb302 Type-C port-controller cannot control the current-limit
directly, so we need to exported the limit 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.

Register a power_supply and export the current-limit through the
power_supply's current-max property.

Cc: "Yueyao (Nathan) Zhu" <yue...@google.com>
Signed-off-by: Hans de Goede <hdego...@redhat.com>

Reviewed-by: Guenter Roeck <li...@roeck-us.net>

---
Changes in v2:
-Put the psy class device code directly in fusb302.c rather then introducing
  helpers which are only used by fusb302.c
-Add an online property to the psy so that upower does not mistake it for a
  second battery in the system
---
  drivers/staging/typec/fusb302/Kconfig   |  2 +-
  drivers/staging/typec/fusb302/fusb302.c | 63 +++++++++++++++++++++++++++++++--
  2 files changed, 62 insertions(+), 3 deletions(-)

diff --git a/drivers/staging/typec/fusb302/Kconfig 
b/drivers/staging/typec/fusb302/Kconfig
index fce099ff39fe..48a4f2fcee03 100644
--- a/drivers/staging/typec/fusb302/Kconfig
+++ b/drivers/staging/typec/fusb302/Kconfig
@@ -1,6 +1,6 @@
  config TYPEC_FUSB302
        tristate "Fairchild FUSB302 Type-C chip driver"
-       depends on I2C
+       depends on I2C && POWER_SUPPLY
        help
          The Fairchild FUSB302 Type-C chip driver that works with
          Type-C Port Controller Manager to provide USB PD and USB
diff --git a/drivers/staging/typec/fusb302/fusb302.c 
b/drivers/staging/typec/fusb302/fusb302.c
index 6f007f66d597..cf6355f59cd9 100644
--- a/drivers/staging/typec/fusb302/fusb302.c
+++ b/drivers/staging/typec/fusb302/fusb302.c
@@ -28,6 +28,7 @@
  #include <linux/of_device.h>
  #include <linux/of_gpio.h>
  #include <linux/pinctrl/consumer.h>
+#include <linux/power_supply.h>
  #include <linux/proc_fs.h>
  #include <linux/regulator/consumer.h>
  #include <linux/sched/clock.h>
@@ -108,6 +109,11 @@ struct fusb302_chip {
        /* lock for sharing chip states */
        struct mutex lock;
+ /* psy + psy status */
+       struct power_supply *psy;
+       u32 current_limit;
+       u32 supply_voltage;
+
        /* chip status */
        enum toggling_mode toggling_mode;
        enum src_current_status src_current_status;
@@ -876,11 +882,13 @@ static int tcpm_set_vbus(struct tcpc_dev *dev, bool on, 
bool charge)
                chip->vbus_on = on;
                fusb302_log(chip, "vbus := %s", on ? "On" : "Off");
        }
-       if (chip->charge_on == charge)
+       if (chip->charge_on == charge) {
                fusb302_log(chip, "charge is already %s",
                            charge ? "On" : "Off");
-       else
+       } else {
                chip->charge_on = charge;
+               power_supply_changed(chip->psy);
+       }
done:
        mutex_unlock(&chip->lock);
@@ -896,6 +904,11 @@ static int tcpm_set_current_limit(struct tcpc_dev *dev, 
u32 max_ma, u32 mv)
        fusb302_log(chip, "current limit: %d ma, %d mv (not implemented)",
                    max_ma, mv);
+ chip->supply_voltage = mv;
+       chip->current_limit = max_ma;
+
+       power_supply_changed(chip->psy);
+
        return 0;
  }
@@ -1681,6 +1694,43 @@ static irqreturn_t fusb302_irq_intn(int irq, void *dev_id)
        return IRQ_HANDLED;
  }
+static int fusb302_psy_get_property(struct power_supply *psy,
+                                   enum power_supply_property psp,
+                                   union power_supply_propval *val)
+{
+       struct fusb302_chip *chip = power_supply_get_drvdata(psy);
+
+       switch (psp) {
+       case POWER_SUPPLY_PROP_ONLINE:
+               val->intval = chip->charge_on;
+               break;
+       case POWER_SUPPLY_PROP_VOLTAGE_NOW:
+               val->intval = chip->supply_voltage * 1000; /* mV -> µV */
+               break;
+       case POWER_SUPPLY_PROP_CURRENT_MAX:
+               val->intval = chip->current_limit * 1000; /* mA -> µA */
+               break;
+       default:
+               return -ENODATA;
+       }
+
+       return 0;
+}
+
+static enum power_supply_property fusb302_psy_properties[] = {
+       POWER_SUPPLY_PROP_ONLINE,
+       POWER_SUPPLY_PROP_VOLTAGE_NOW,
+       POWER_SUPPLY_PROP_CURRENT_MAX,
+};
+
+const struct power_supply_desc fusb302_psy_desc = {
+       .name           = "fusb302-typec-source",
+       .type           = POWER_SUPPLY_TYPE_USB_TYPE_C,
+       .properties     = fusb302_psy_properties,
+       .num_properties = ARRAY_SIZE(fusb302_psy_properties),
+       .get_property   = fusb302_psy_get_property,
+};
+
  static int init_gpio(struct fusb302_chip *chip)
  {
        struct device_node *node;
@@ -1720,6 +1770,7 @@ static int fusb302_probe(struct i2c_client *client,
        struct fusb302_chip *chip;
        struct i2c_adapter *adapter;
        struct device *dev = &client->dev;
+       struct power_supply_config cfg = {};
        const char *name;
        int ret = 0;
        u32 v;
@@ -1766,6 +1817,14 @@ static int fusb302_probe(struct i2c_client *client,
                        return -EPROBE_DEFER;
        }
+ cfg.drv_data = chip;
+       chip->psy = devm_power_supply_register(dev, &fusb302_psy_desc, &cfg);
+       if (IS_ERR(chip->psy)) {
+               ret = PTR_ERR(chip->psy);
+               dev_err(chip->dev, "Error registering power-supply: %d\n", ret);
+               return ret;
+       }
+
        ret = fusb302_debugfs_init(chip);
        if (ret < 0)
                return ret;


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