[PATCH v2 3/4] power: supply: max17040: Config alert SOC low level threshold from FDT

[Matheus Castello]

For configuration of fuel gauge alert for a low level state of charge
interrupt we add a function to config level threshold and a device tree
binding property to set it in flatned device tree node.

Now we can use "maxim,alert-soc-level" property with the values from
1 up to 32 to configure alert interrupt threshold.

Signed-off-by: Matheus Castello <math...@castello.eng.br>
---
 drivers/power/supply/max17040_battery.c | 56 ++++++++++++++++++++++---
 1 file changed, 50 insertions(+), 6 deletions(-)

diff --git a/drivers/power/supply/max17040_battery.c 
b/drivers/power/supply/max17040_battery.c
index 8d2f8ed3f44c..f036f272d52f 100644
--- a/drivers/power/supply/max17040_battery.c
+++ b/drivers/power/supply/max17040_battery.c
@@ -29,6 +29,9 @@
 #define MAX17040_DELAY         1000
 #define MAX17040_BATTERY_FULL  95
 
+#define MAX17040_ATHD_MASK             0xFFE0
+#define MAX17040_ATHD_DEFAULT_POWER_UP 4
+
 struct max17040_chip {
        struct i2c_client               *client;
        struct delayed_work             work;
@@ -43,6 +46,8 @@ struct max17040_chip {
        int soc;
        /* State Of Charge */
        int status;
+       /* Alert threshold from 32% to 1% of the State of Charge */
+       u32 alert_threshold;
 };
 
 static int max17040_get_property(struct power_supply *psy,
@@ -119,6 +124,27 @@ static void max17040_get_soc(struct i2c_client *client)
        chip->soc = (soc >> 8);
 }
 
+static int max17040_set_soc_threshold(struct i2c_client *client, u32 level)
+{
+       int ret;
+       u16 data;
+
+       /* check if level is between 1% and 32% */
+       if (level > 0 && level < 33) {
+               /* alert threshold use LSb 5 bits from RCOMP */
+               level = 32 - level;
+               data = max17040_read_reg(client, MAX17040_RCOMP);
+               data &= MAX17040_ATHD_MASK;
+               data |= level;
+               max17040_write_reg(client, MAX17040_RCOMP, data);
+               ret = 0;
+       } else {
+               ret = -EINVAL;
+       }
+
+       return ret;
+}
+
 static void max17040_get_version(struct i2c_client *client)
 {
        u16 version;
@@ -161,6 +187,16 @@ static void max17040_get_status(struct i2c_client *client)
                chip->status = POWER_SUPPLY_STATUS_FULL;
 }
 
+static void max17040_get_of_data(struct max17040_chip *chip)
+{
+       struct device *dev = &chip->client->dev;
+       struct device_node *np = dev->of_node;
+
+       if (of_property_read_u32(np, "maxim,alert-soc-level",
+                       &chip->alert_threshold))
+               chip->alert_threshold = MAX17040_ATHD_DEFAULT_POWER_UP;
+}
+
 static void max17040_check_changes(struct i2c_client *client)
 {
        max17040_get_vcell(client);
@@ -226,6 +262,7 @@ static int max17040_probe(struct i2c_client *client,
 
        chip->client = client;
        chip->pdata = client->dev.platform_data;
+       max17040_get_of_data(chip);
 
        i2c_set_clientdata(client, chip);
        psy_cfg.drv_data = chip;
@@ -237,16 +274,26 @@ static int max17040_probe(struct i2c_client *client,
                return PTR_ERR(chip->battery);
        }
 
+       max17040_reset(client);
+       max17040_get_version(client);
+
        /* check interrupt */
        if (client->irq) {
                int ret;
-               unsigned int flags;
+
+               ret = max17040_set_soc_threshold(client, chip->alert_threshold);
+               if (ret) {
+                       dev_err(&client->dev,
+                               "Failed to set SOC alert threshold: err %d\n",
+                               ret);
+                       return ret;
+               }
 
                dev_info(&client->dev, "IRQ: enabled\n");
-               flags = IRQF_TRIGGER_FALLING | IRQF_ONESHOT;
 
                ret = devm_request_threaded_irq(&client->dev, client->irq, NULL,
-                                               max17040_thread_handler, flags,
+                                               max17040_thread_handler,
+                                               (client->flags | IRQF_ONESHOT),
                                                chip->battery->desc->name,
                                                chip);
 
@@ -258,9 +305,6 @@ static int max17040_probe(struct i2c_client *client,
                }
        }
 
-       max17040_reset(client);
-       max17040_get_version(client);
-
        INIT_DEFERRABLE_WORK(&chip->work, max17040_work);
        queue_delayed_work(system_power_efficient_wq, &chip->work,
                           MAX17040_DELAY);
-- 
2.17.0