[PATCHv1 1/2] power: supply: gpio-charger: add charge-current-limit feature

From: Sebastian Reichel
Date: Wed May 13 2020 - 07:56:24 EST

Add new charge-current-limit feature to gpio-charger. This also
makes the online status GPIO optional, since hardware might only
expose the charge-current-limit feature and there is no good reason
to have it mandatory now that different GPIOs are supported.

Signed-off-by: Sebastian Reichel <sebastian.reichel@xxxxxxxxxxxxx>
---
.../bindings/power/supply/gpio-charger.txt | 11 +-
drivers/power/supply/gpio-charger.c | 176 ++++++++++++++++--
2 files changed, 174 insertions(+), 13 deletions(-)

diff --git a/Documentation/devicetree/bindings/power/supply/gpio-charger.txt b/Documentation/devicetree/bindings/power/supply/gpio-charger.txt
index 0fb33b2c62a6..dbfd29029f69 100644
--- a/Documentation/devicetree/bindings/power/supply/gpio-charger.txt
+++ b/Documentation/devicetree/bindings/power/supply/gpio-charger.txt
@@ -2,8 +2,6 @@ gpio-charger

Required properties :
- compatible : "gpio-charger"
- - gpios : GPIO indicating the charger presence.
- See GPIO binding in bindings/gpio/gpio.txt .
- charger-type : power supply type, one of
unknown
battery
@@ -15,7 +13,13 @@ Required properties :
usb-aca (USB accessory charger adapter)

Optional properties:
+ - gpios : GPIO indicating the charger presence.
+ See GPIO binding in bindings/gpio/gpio.txt .
- charge-status-gpios: GPIO indicating whether a battery is charging.
+ - charge-current-limit-gpios: Output GPIOs specifiers for limiting the charge current
+ - charge-current-limit-mapping: List of touples with current in uA and a GPIO bitmap (in this order).
+ The GPIOs are encoded in the same order as specified in charge-current-limit-gpios.
+ The touples must be provided in descending order of the current limit.

Example:

@@ -24,6 +28,9 @@ Example:
charger-type = "usb-sdp";
gpios = <&gpd 28 GPIO_ACTIVE_LOW>;
charge-status-gpios = <&gpc 27 GPIO_ACTIVE_LOW>;
+
+ charge-current-limit-gpios = <&gpioA 11 GPIO_ACTIVE_HIGH>, <&gpioA 12 GPIO_ACTIVE_HIGH>;
+ charge-current-limit-mapping = <2500000 0x00>, <700000 0x01>, <0 0x02>;
};

battery {
diff --git a/drivers/power/supply/gpio-charger.c b/drivers/power/supply/gpio-charger.c
index 1b959c7f8b0e..4a5eac7cc36c 100644
--- a/drivers/power/supply/gpio-charger.c
+++ b/drivers/power/supply/gpio-charger.c
@@ -18,7 +18,13 @@

#include <linux/power/gpio-charger.h>

+struct gpio_mapping {
+ u32 limit_ua;
+ u32 gpiodata;
+} __packed;
+
struct gpio_charger {
+ struct device *dev;
unsigned int irq;
unsigned int charge_status_irq;
bool wakeup_enabled;
@@ -27,6 +33,11 @@ struct gpio_charger {
struct power_supply_desc charger_desc;
struct gpio_desc *gpiod;
struct gpio_desc *charge_status;
+
+ struct gpio_descs *current_limit_gpios;
+ struct gpio_mapping *current_limit_map;
+ u32 current_limit_map_size;
+ u32 charge_current_limit;
};

static irqreturn_t gpio_charger_irq(int irq, void *devid)
@@ -43,6 +54,35 @@ static inline struct gpio_charger *psy_to_gpio_charger(struct power_supply *psy)
return power_supply_get_drvdata(psy);
}

+static int set_charge_current_limit(struct gpio_charger *gpio_charger, int val)
+{
+ struct gpio_mapping mapping;
+ int ndescs = gpio_charger->current_limit_gpios->ndescs;
+ struct gpio_desc **gpios = gpio_charger->current_limit_gpios->desc;
+ int i;
+
+ if (!gpio_charger->current_limit_map_size)
+ return -EINVAL;
+
+ for (i = 0; i < gpio_charger->current_limit_map_size; i++) {
+ if (gpio_charger->current_limit_map[i].limit_ua <= val)
+ break;
+ }
+ mapping = gpio_charger->current_limit_map[i];
+
+ for (i = 0; i < ndescs; i++) {
+ bool val = (mapping.gpiodata >> i) & 1;
+ gpiod_set_value_cansleep(gpios[ndescs-i-1], val);
+ }
+
+ gpio_charger->charge_current_limit = mapping.limit_ua;
+
+ dev_dbg(gpio_charger->dev, "set charge current limit to %d (requested: %d)\n",
+ gpio_charger->charge_current_limit, val);
+
+ return 0;
+}
+
static int gpio_charger_get_property(struct power_supply *psy,
enum power_supply_property psp, union power_supply_propval *val)
{
@@ -58,6 +98,9 @@ static int gpio_charger_get_property(struct power_supply *psy,
else
val->intval = POWER_SUPPLY_STATUS_NOT_CHARGING;
break;
+ case POWER_SUPPLY_PROP_CONSTANT_CHARGE_CURRENT_MAX:
+ val->intval = gpio_charger->charge_current_limit;
+ break;
default:
return -EINVAL;
}
@@ -65,6 +108,34 @@ static int gpio_charger_get_property(struct power_supply *psy,
return 0;
}

+static int gpio_charger_set_property(struct power_supply *psy,
+ enum power_supply_property psp, const union power_supply_propval *val)
+{
+ struct gpio_charger *gpio_charger = psy_to_gpio_charger(psy);
+
+ switch (psp) {
+ case POWER_SUPPLY_PROP_CONSTANT_CHARGE_CURRENT_MAX:
+ return set_charge_current_limit(gpio_charger, val->intval);
+ default:
+ return -EINVAL;
+ }
+
+ return 0;
+}
+
+static int gpio_charger_property_is_writeable(struct power_supply *psy,
+ enum power_supply_property psp)
+{
+ switch (psp) {
+ case POWER_SUPPLY_PROP_CONSTANT_CHARGE_CURRENT_MAX:
+ return 1;
+ default:
+ break;
+ }
+
+ return 0;
+}
+
static enum power_supply_type gpio_charger_get_type(struct device *dev)
{
const char *chargetype;
@@ -112,9 +183,70 @@ static int gpio_charger_get_irq(struct device *dev, void *dev_id,
return irq;
}

+static int init_charge_current_limit(struct device *dev,
+ struct gpio_charger *gpio_charger)
+{
+ int i, len;
+ u32 cur_limit = U32_MAX;
+
+ gpio_charger->current_limit_gpios = devm_gpiod_get_array_optional(dev,
+ "charge-current-limit", GPIOD_OUT_LOW);
+ if (IS_ERR(gpio_charger->current_limit_gpios)) {
+ dev_err(dev, "error getting current-limit GPIOs\n");
+ return PTR_ERR(gpio_charger->current_limit_gpios);
+ }
+
+ if (!gpio_charger->current_limit_gpios)
+ return 0;
+
+ len = device_property_read_u32_array(dev, "charge-current-limit-mapping",
+ NULL, 0);
+ if (len < 0)
+ return len;
+
+ if (len % 2) {
+ dev_err(dev, "invalid charge-current-limit-mapping length\n");
+ return -EINVAL;
+ }
+
+ gpio_charger->current_limit_map = devm_kmalloc_array(dev,
+ len / 2, sizeof(*gpio_charger->current_limit_map), GFP_KERNEL);
+ if (!gpio_charger->current_limit_map)
+ return -ENOMEM;
+
+ gpio_charger->current_limit_map_size = len / 2;
+
+ len = device_property_read_u32_array(dev, "charge-current-limit-mapping",
+ (u32*) gpio_charger->current_limit_map, len);
+ if (len < 0)
+ return len;
+
+ for (i=0; i < gpio_charger->current_limit_map_size; i++) {
+ if (gpio_charger->current_limit_map[i].limit_ua > cur_limit) {
+ dev_err(dev, "invalid charge-current-limit-mapping\n");
+ return -EINVAL;
+ }
+
+ cur_limit = gpio_charger->current_limit_map[i].limit_ua;
+ }
+
+ /* default to smallest current limitation for safety reasons */
+ len = gpio_charger->current_limit_map_size - 1;
+ set_charge_current_limit(gpio_charger,
+ gpio_charger->current_limit_map[len].limit_ua);
+
+ return 0;
+}
+
+/*
+ * The entries will be overwritten by driver's probe routine depending
+ * on the available features. This list ensures, that the array is big
+ * enough for all optional features.
+ */
static enum power_supply_property gpio_charger_properties[] = {
POWER_SUPPLY_PROP_ONLINE,
- POWER_SUPPLY_PROP_STATUS /* Must always be last in the array. */
+ POWER_SUPPLY_PROP_STATUS,
+ POWER_SUPPLY_PROP_CONSTANT_CHARGE_CURRENT_MAX,
};

static int gpio_charger_probe(struct platform_device *pdev)
@@ -128,6 +260,7 @@ static int gpio_charger_probe(struct platform_device *pdev)
int charge_status_irq;
unsigned long flags;
int ret;
+ int num_props = 0;

if (!pdata && !dev->of_node) {
dev_err(dev, "No platform data\n");
@@ -137,18 +270,19 @@ static int gpio_charger_probe(struct platform_device *pdev)
gpio_charger = devm_kzalloc(dev, sizeof(*gpio_charger), GFP_KERNEL);
if (!gpio_charger)
return -ENOMEM;
+ gpio_charger->dev = dev;

/*
* This will fetch a GPIO descriptor from device tree, ACPI or
* boardfile descriptor tables. It's good to try this first.
*/
- gpio_charger->gpiod = devm_gpiod_get(dev, NULL, GPIOD_IN);
+ gpio_charger->gpiod = devm_gpiod_get_optional(dev, NULL, GPIOD_IN);

/*
* If this fails and we're not using device tree, try the
* legacy platform data method.
*/
- if (IS_ERR(gpio_charger->gpiod) && !dev->of_node) {
+ if (!gpio_charger->gpiod && !dev->of_node) {
/* Non-DT: use legacy GPIO numbers */
if (!gpio_is_valid(pdata->gpio)) {
dev_err(dev, "Invalid gpio pin in pdata\n");
@@ -173,18 +307,38 @@ static int gpio_charger_probe(struct platform_device *pdev)
return PTR_ERR(gpio_charger->gpiod);
}

+ if (gpio_charger->gpiod &&
+ num_props < ARRAY_SIZE(gpio_charger_properties)) {
+ gpio_charger_properties[num_props] = POWER_SUPPLY_PROP_ONLINE;
+ num_props++;
+ }
+
charge_status = devm_gpiod_get_optional(dev, "charge-status", GPIOD_IN);
- gpio_charger->charge_status = charge_status;
- if (IS_ERR(gpio_charger->charge_status))
- return PTR_ERR(gpio_charger->charge_status);
+ if (IS_ERR(charge_status))
+ return PTR_ERR(charge_status);
+ if (charge_status && num_props < ARRAY_SIZE(gpio_charger_properties)) {
+ gpio_charger->charge_status = charge_status;
+ gpio_charger_properties[num_props] = POWER_SUPPLY_PROP_STATUS;
+ num_props++;
+ }
+
+ ret = init_charge_current_limit(dev, gpio_charger);
+ if (ret < 0)
+ return ret;
+ if (gpio_charger->current_limit_map &&
+ num_props < ARRAY_SIZE(gpio_charger_properties)) {
+ gpio_charger_properties[num_props] =
+ POWER_SUPPLY_PROP_CONSTANT_CHARGE_CURRENT_MAX;
+ num_props++;
+ }

charger_desc = &gpio_charger->charger_desc;
charger_desc->properties = gpio_charger_properties;
- charger_desc->num_properties = ARRAY_SIZE(gpio_charger_properties);
- /* Remove POWER_SUPPLY_PROP_STATUS from the supported properties. */
- if (!gpio_charger->charge_status)
- charger_desc->num_properties -= 1;
+ charger_desc->num_properties = num_props;
charger_desc->get_property = gpio_charger_get_property;
+ charger_desc->set_property = gpio_charger_set_property;
+ charger_desc->property_is_writeable =
+ gpio_charger_property_is_writeable;

psy_cfg.of_node = dev->of_node;
psy_cfg.drv_data = gpio_charger;
@@ -269,6 +423,6 @@ static struct platform_driver gpio_charger_driver = {
module_platform_driver(gpio_charger_driver);

MODULE_AUTHOR("Lars-Peter Clausen <lars@xxxxxxxxxx>");
-MODULE_DESCRIPTION("Driver for chargers which report their online status through a GPIO");
+MODULE_DESCRIPTION("Driver for chargers only communicating via GPIO(s)");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:gpio-charger");
--
2.26.2