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power: supply: gpio-charger: add charge-current-limit feature
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Add new charge-current-limit feature to gpio-charger.

Reviewed-by: Linus Walleij <[email protected]>
Signed-off-by: Sebastian Reichel <[email protected]>
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@sre
sre committed Aug 27, 2020
1 parent 39e95bb commit be2919d
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31 changes: 31 additions & 0 deletions Documentation/devicetree/bindings/power/supply/gpio-charger.yaml
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Original file line number Diff line number Diff line change
Expand Up @@ -39,6 +39,25 @@ properties:
maxItems: 1
description: GPIO indicating the charging status

charge-current-limit-gpios:
minItems: 1
maxItems: 32
description: GPIOs used for current limiting

charge-current-limit-mapping:
description: List of tuples with current in uA and a GPIO bitmap (in
this order). The tuples must be provided in descending order of the
current limit.
$ref: /schemas/types.yaml#/definitions/uint32-matrix
items:
items:
- description:
Current limit in uA
- description:
Encoded GPIO setting. Bit 0 represents last GPIO from the
charge-current-limit-gpios property. Bit 1 second to last
GPIO and so on.

required:
- compatible

Expand All @@ -47,6 +66,12 @@ anyOf:
- gpios
- required:
- charge-status-gpios
- required:
- charge-current-limit-gpios

dependencies:
charge-current-limit-gpios: [ charge-current-limit-mapping ]
charge-current-limit-mapping: [ charge-current-limit-gpios ]

additionalProperties: false

Expand All @@ -60,4 +85,10 @@ examples:
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>, // 2.5 A => both GPIOs low
<700000 0x01>, // 700 mA => GPIO A.12 high
<0 0x02>; // 0 mA => GPIO A.11 high
};
140 changes: 140 additions & 0 deletions drivers/power/supply/gpio-charger.c
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Original file line number Diff line number Diff line change
Expand Up @@ -17,7 +17,13 @@

#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;
Expand All @@ -26,6 +32,11 @@ 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)
Expand All @@ -42,6 +53,35 @@ 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)
{
Expand All @@ -57,13 +97,44 @@ 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;
}

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;
Expand Down Expand Up @@ -111,6 +182,61 @@ 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 == 0 || 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, "charge-current-limit-mapping not sorted by current in descending order\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
Expand All @@ -119,6 +245,7 @@ static int gpio_charger_get_irq(struct device *dev, void *dev_id,
static enum power_supply_property gpio_charger_properties[] = {
POWER_SUPPLY_PROP_ONLINE,
POWER_SUPPLY_PROP_STATUS,
POWER_SUPPLY_PROP_CONSTANT_CHARGE_CURRENT_MAX,
};

static int gpio_charger_probe(struct platform_device *pdev)
Expand All @@ -141,6 +268,7 @@ 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
Expand All @@ -167,10 +295,22 @@ static int gpio_charger_probe(struct platform_device *pdev)
num_props++;
}

ret = init_charge_current_limit(dev, gpio_charger);
if (ret < 0)
return ret;
if (gpio_charger->current_limit_map) {
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 = 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;
Expand Down

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