* [PATCH 1/2] dt-bindings: power: supply: maxim,max8903: add DC and USB input current-limit controls
2026-06-03 7:15 [PATCH 0/2] power: supply: max8903: add GPIO-controlled input current-limit Herman van Hazendonk
@ 2026-06-03 7:15 ` Herman van Hazendonk
2026-06-03 7:15 ` [PATCH 2/2] power: supply: max8903: add DC and USB input current-limit GPIO controls Herman van Hazendonk
1 sibling, 0 replies; 3+ messages in thread
From: Herman van Hazendonk @ 2026-06-03 7:15 UTC (permalink / raw)
To: sre
Cc: robh, krzk+dt, conor+dt, linux-pm, devicetree, linux-kernel,
Herman van Hazendonk
Add four optional properties to the MAX8903 charger binding to
describe board-level GPIO control of the DC and USB input current
limits:
DC input (TA / DOK pin):
- dc-current-limit-gpios (1..4 GPIOs): mux control lines feeding
the MAX8903 IDC resistor mux;
- dc-current-limit-mapping (uint32-matrix of {microamps,
gpio_bit_pattern} pairs): the available current levels and the
GPIO bit pattern that selects each level.
USB input (USB / UOK pin):
- usb-current-limit-gpios: a single GPIO driving the IUSB
tri-state pin (low / high);
- usb-current-limit-values: the two microamp values that the IUSB
pin selects.
These let userspace clamp the input draw via the standard
POWER_SUPPLY_PROP_INPUT_CURRENT_LIMIT power_supply attribute. The HP
TouchPad uses both: two TLMM lines select between 0.5 A, 1.0 A,
1.5 A and 2.0 A DC input current limits behind the MAX8903B
charger, and a third TLMM line picks the IUSB 100 mA / 500 mA
limit.
These are purely additive; existing platforms remain unaffected.
Signed-off-by: Herman van Hazendonk <github.com@herrie.org>
---
.../bindings/power/supply/maxim,max8903.yaml | 58 +++++++++++++++++++
1 file changed, 58 insertions(+)
diff --git a/Documentation/devicetree/bindings/power/supply/maxim,max8903.yaml b/Documentation/devicetree/bindings/power/supply/maxim,max8903.yaml
index 86af38378999..5e970ebc08df 100644
--- a/Documentation/devicetree/bindings/power/supply/maxim,max8903.yaml
+++ b/Documentation/devicetree/bindings/power/supply/maxim,max8903.yaml
@@ -44,6 +44,41 @@ properties:
maxItems: 1
description: USB suspend pin (active high, output)
+ dc-current-limit-gpios:
+ minItems: 1
+ maxItems: 4
+ description:
+ GPIOs controlling DC input current limit via resistor mux.
+ Used with dc-current-limit-mapping to select charging current.
+
+ dc-current-limit-mapping:
+ $ref: /schemas/types.yaml#/definitions/uint32-matrix
+ minItems: 2
+ maxItems: 16
+ description: |
+ Array of (current_microamps, gpio_bit_pattern) pairs defining available
+ DC current limits. The gpio_bit_pattern is applied to dc-current-limit-gpios
+ to select that current level.
+ items:
+ items:
+ - description: Current limit in microamps
+ - description: GPIO bit pattern value
+
+ usb-current-limit-gpios:
+ maxItems: 1
+ description:
+ GPIO controlling USB input current limit.
+ Low = usb-current-limit-values[0], High = usb-current-limit-values[1].
+
+ usb-current-limit-values:
+ $ref: /schemas/types.yaml#/definitions/uint32-array
+ minItems: 2
+ maxItems: 2
+ default: [100000, 500000]
+ description:
+ USB current limits in microamps for GPIO low and high states.
+ Default is 100mA (low) and 500mA (high) per USB specification.
+
required:
- compatible
@@ -65,3 +100,26 @@ examples:
chg-gpios = <&gpio3 15 GPIO_ACTIVE_LOW>;
cen-gpios = <&gpio2 5 GPIO_ACTIVE_LOW>;
};
+ - |
+ /* Example with DC and USB current limit control */
+ #include <dt-bindings/gpio/gpio.h>
+ charger-with-current-limit {
+ compatible = "maxim,max8903";
+ dok-gpios = <&gpio2 3 GPIO_ACTIVE_LOW>;
+ flt-gpios = <&gpio2 2 GPIO_ACTIVE_LOW>;
+ chg-gpios = <&gpio3 15 GPIO_ACTIVE_LOW>;
+ cen-gpios = <&gpio2 5 GPIO_ACTIVE_LOW>;
+ dcm-gpios = <&gpio2 6 GPIO_ACTIVE_HIGH>;
+
+ /* DC input current limit via IDC resistor mux */
+ dc-current-limit-gpios = <&gpio1 0 GPIO_ACTIVE_HIGH>,
+ <&gpio1 1 GPIO_ACTIVE_HIGH>;
+ dc-current-limit-mapping = <750000 0>, /* GPIO[1:0]=0b00 */
+ <900000 1>, /* GPIO[1:0]=0b01 */
+ <1400000 3>, /* GPIO[1:0]=0b11 */
+ <2000000 2>; /* GPIO[1:0]=0b10 */
+
+ /* USB current control */
+ usb-current-limit-gpios = <&gpio1 2 GPIO_ACTIVE_HIGH>;
+ usb-current-limit-values = <100000 500000>; /* 100mA / 500mA */
+ };
--
2.43.0
^ permalink raw reply related [flat|nested] 3+ messages in thread* [PATCH 2/2] power: supply: max8903: add DC and USB input current-limit GPIO controls
2026-06-03 7:15 [PATCH 0/2] power: supply: max8903: add GPIO-controlled input current-limit Herman van Hazendonk
2026-06-03 7:15 ` [PATCH 1/2] dt-bindings: power: supply: maxim,max8903: add DC and USB input current-limit controls Herman van Hazendonk
@ 2026-06-03 7:15 ` Herman van Hazendonk
1 sibling, 0 replies; 3+ messages in thread
From: Herman van Hazendonk @ 2026-06-03 7:15 UTC (permalink / raw)
To: sre
Cc: robh, krzk+dt, conor+dt, linux-pm, devicetree, linux-kernel,
Herman van Hazendonk
Add two optional current-limit knobs surfaced through
POWER_SUPPLY_PROP_INPUT_CURRENT_LIMIT, selected by which input source
is currently online:
- DC (DOK / TA-IN): a "dc-current-limit-gpios" array drives the
GPIOs of an external resistor mux connected to the MAX8903 IDC pin
(DC Current-Limit Set Input, pin 11). The IDC pin programs the
step-down DC input current limit from 0.5 A to 2 A via R_IDC when
the DCM mode pin is logic-high. The DT property
"dc-current-limit-mapping" describes the (current_ua, gpio_value)
pairs the board can program; the driver picks the largest entry
whose limit is <= the requested limit. A 0 uA entry, used to
stop drawing DC current, is selectable by issuing a 0 uA request
(the selection uses a -1 "not found" sentinel rather than
tracking best_limit > 0, so the all-zero entry can win).
- USB (UOK / USB-IN): a single "usb-current-limit-gpio" drives the
MAX8903 IUSB pin (USB Current-Limit Set Input, pin 7). Logic-low
selects 100 mA; logic-high selects 500 mA per the MAX8903 spec.
The DT property "usb-current-limit-values" overrides those limits
for boards with non-standard IUSB thresholds. The requested limit
selects the highest of the two configured values that does not
exceed the cap: requests at or above the high value pick high,
requests at or above the low value pick low, and a request below
the low value is rejected with -EINVAL rather than silently
programming a higher current that would violate the system power
budget.
The dispatch in max8903_set_property() to the DC vs USB path needs to
match the active source flag set by the corresponding *_ok GPIO IRQ
handler; both update sites take a new struct mutex source_lock so the
check and the resulting hardware write cannot be torn by a concurrent
IRQ flipping the source-online flag mid-decision. The IRQs are
requested with IRQF_ONESHOT (threaded), so a sleepable lock is the
right primitive in both contexts. max8903_get_property() also takes
source_lock briefly to snapshot the source flags and current-limit
values so userspace never observes a torn pair of
(source-online flag, current-limit ua).
dc-current-limit-mapping gpio_value entries are validated at parse
against the GPIO array width so a malformed DT value is rejected
instead of being silently truncated by gpiod_set_array_value() and
selecting the wrong mux level. The mapping is additionally required
to contain a gpio_value=0 entry: devm_gpiod_get_array_optional()
asks for GPIOD_OUT_LOW, so the hardware mux starts at gpio_value 0,
and the driver seeds dc_current_limit_ua from the matching map entry.
A DT lacking the all-zero entry is rejected with -EINVAL because
otherwise the reported INPUT_CURRENT_LIMIT could disagree with the
mux state until a set_property write picks a real value.
Signed-off-by: Herman van Hazendonk <github.com@herrie.org>
---
drivers/power/supply/max8903_charger.c | 369 ++++++++++++++++++++++++-
1 file changed, 358 insertions(+), 11 deletions(-)
diff --git a/drivers/power/supply/max8903_charger.c b/drivers/power/supply/max8903_charger.c
index 45fbaad6c647..19c2b348a045 100644
--- a/drivers/power/supply/max8903_charger.c
+++ b/drivers/power/supply/max8903_charger.c
@@ -9,11 +9,18 @@
#include <linux/gpio/consumer.h>
#include <linux/interrupt.h>
#include <linux/module.h>
+#include <linux/mutex.h>
#include <linux/of.h>
+#include <linux/property.h>
#include <linux/slab.h>
#include <linux/power_supply.h>
#include <linux/platform_device.h>
+struct max8903_current_limit_mapping {
+ u32 limit_ua; /* Current limit in microamps */
+ u32 gpio_value; /* GPIO bit pattern */
+};
+
struct max8903_data {
struct device *dev;
struct power_supply *psy;
@@ -31,6 +38,27 @@ struct max8903_data {
struct gpio_desc *flt; /* Fault output */
struct gpio_desc *dcm; /* Current-Limit Mode input (1: DC, 2: USB) */
struct gpio_desc *usus; /* USB Suspend Input (1: suspended) */
+
+ /* DC current limit control (ISET pins) */
+ struct gpio_descs *dc_current_limit_gpios;
+ struct max8903_current_limit_mapping *dc_current_limit_map;
+ u32 dc_current_limit_map_size;
+ u32 dc_current_limit_ua; /* Current setting in uA */
+
+ /* USB current limit control (IUSB pin) */
+ struct gpio_desc *usb_current_limit_gpio;
+ u32 usb_current_limit_low_ua; /* Current when GPIO low */
+ u32 usb_current_limit_high_ua; /* Current when GPIO high */
+ u32 usb_current_limit_ua; /* Current setting in uA */
+
+ /*
+ * Serialises ta_in / usb_in updates against
+ * max8903_set_property() which steers the current-limit write to
+ * the DC or USB path based on which source is currently online.
+ * The IRQ handlers are requested with IRQF_ONESHOT (threaded), so
+ * a sleepable mutex is the right primitive in both contexts.
+ */
+ struct mutex source_lock;
bool fault;
bool usb_in;
bool ta_in;
@@ -40,6 +68,7 @@ static enum power_supply_property max8903_charger_props[] = {
POWER_SUPPLY_PROP_STATUS, /* Charger status output */
POWER_SUPPLY_PROP_ONLINE, /* External power source */
POWER_SUPPLY_PROP_HEALTH, /* Fault or OK */
+ POWER_SUPPLY_PROP_INPUT_CURRENT_LIMIT, /* Input current limit */
};
static int max8903_get_property(struct power_supply *psy,
@@ -47,6 +76,24 @@ static int max8903_get_property(struct power_supply *psy,
union power_supply_propval *val)
{
struct max8903_data *data = power_supply_get_drvdata(psy);
+ bool ta_in, usb_in;
+ u32 dc_limit, usb_limit;
+
+ /*
+ * Snapshot the source flags and current-limit settings under the
+ * source_lock that the IRQs (max8903_dcin / max8903_usbin) and
+ * max8903_set_property() take when updating them, so we never
+ * observe a torn pair of (source-online flag, current-limit ua).
+ * The gpiod_get_value() reads further down deliberately stay
+ * outside the lock — they hit the GPIO controller, not driver
+ * state, and the IRQs do not touch them under the lock either.
+ */
+ mutex_lock(&data->source_lock);
+ ta_in = data->ta_in;
+ usb_in = data->usb_in;
+ dc_limit = data->dc_current_limit_ua;
+ usb_limit = data->usb_current_limit_ua;
+ mutex_unlock(&data->source_lock);
switch (psp) {
case POWER_SUPPLY_PROP_STATUS:
@@ -55,21 +102,31 @@ static int max8903_get_property(struct power_supply *psy,
if (gpiod_get_value(data->chg))
/* CHG asserted */
val->intval = POWER_SUPPLY_STATUS_CHARGING;
- else if (data->usb_in || data->ta_in)
+ else if (usb_in || ta_in)
val->intval = POWER_SUPPLY_STATUS_NOT_CHARGING;
else
val->intval = POWER_SUPPLY_STATUS_DISCHARGING;
}
break;
case POWER_SUPPLY_PROP_ONLINE:
- val->intval = 0;
- if (data->usb_in || data->ta_in)
- val->intval = 1;
+ val->intval = (ta_in || usb_in) ? 1 : 0;
break;
case POWER_SUPPLY_PROP_HEALTH:
- val->intval = POWER_SUPPLY_HEALTH_GOOD;
- if (data->fault)
- val->intval = POWER_SUPPLY_HEALTH_UNSPEC_FAILURE;
+ /*
+ * data->fault is a single bool toggled from one IRQ
+ * handler, so a torn read is not possible; no need to
+ * extend source_lock coverage here.
+ */
+ val->intval = data->fault ? POWER_SUPPLY_HEALTH_UNSPEC_FAILURE
+ : POWER_SUPPLY_HEALTH_GOOD;
+ break;
+ case POWER_SUPPLY_PROP_INPUT_CURRENT_LIMIT:
+ if (ta_in && data->dc_current_limit_gpios)
+ val->intval = dc_limit;
+ else if (usb_in && data->usb_current_limit_gpio)
+ val->intval = usb_limit;
+ else
+ return -ENODATA;
break;
default:
return -EINVAL;
@@ -78,6 +135,130 @@ static int max8903_get_property(struct power_supply *psy,
return 0;
}
+static int max8903_set_dc_current_limit(struct max8903_data *data, u32 limit_ua)
+{
+ int i, best_idx = -1;
+ u32 best_gpio_value;
+ /*
+ * gpio_value is a u32 in the DT mapping and is parse-time
+ * validated to fit in BIT(ndescs); size the bitmap to the full
+ * width of the source u32 so a DT with up to 32 dc-current-limit
+ * GPIOs cannot overflow this stack buffer.
+ */
+ DECLARE_BITMAP(values, BITS_PER_TYPE(u32));
+
+ if (!data->dc_current_limit_gpios)
+ return -EOPNOTSUPP;
+
+ /*
+ * Find the highest supported current <= requested. Use a -1
+ * "not found" sentinel rather than tracking best_limit > 0 so
+ * that a 0 uA entry (used to disable charging) can be selected
+ * by a 0 uA request.
+ */
+ for (i = 0; i < data->dc_current_limit_map_size; i++) {
+ if (data->dc_current_limit_map[i].limit_ua > limit_ua)
+ continue;
+ if (best_idx < 0 ||
+ data->dc_current_limit_map[i].limit_ua >
+ data->dc_current_limit_map[best_idx].limit_ua)
+ best_idx = i;
+ }
+
+ if (best_idx < 0)
+ return -EINVAL;
+
+ best_gpio_value = data->dc_current_limit_map[best_idx].gpio_value;
+ bitmap_from_arr32(values, &best_gpio_value, BITS_PER_TYPE(u32));
+ gpiod_set_array_value_cansleep(data->dc_current_limit_gpios->ndescs,
+ data->dc_current_limit_gpios->desc,
+ data->dc_current_limit_gpios->info,
+ values);
+
+ data->dc_current_limit_ua = data->dc_current_limit_map[best_idx].limit_ua;
+ dev_dbg(data->dev, "DC current limit set to %u uA\n",
+ data->dc_current_limit_ua);
+
+ return 0;
+}
+
+static int max8903_set_usb_current_limit(struct max8903_data *data, u32 limit_ua)
+{
+ u32 selected;
+ int gpio_val;
+
+ if (!data->usb_current_limit_gpio)
+ return -EOPNOTSUPP;
+
+ /*
+ * Pick the highest of the two configured limits that does not
+ * exceed the requested cap. Mirror the DC path's policy: if
+ * neither value fits (the request is below even the low limit),
+ * refuse the request rather than silently program a higher
+ * current that violates the system power budget.
+ */
+ if (limit_ua >= data->usb_current_limit_high_ua) {
+ selected = data->usb_current_limit_high_ua;
+ gpio_val = 1;
+ } else if (limit_ua >= data->usb_current_limit_low_ua) {
+ selected = data->usb_current_limit_low_ua;
+ gpio_val = 0;
+ } else {
+ return -EINVAL;
+ }
+
+ gpiod_set_value_cansleep(data->usb_current_limit_gpio, gpio_val);
+ data->usb_current_limit_ua = selected;
+
+ dev_dbg(data->dev, "USB current limit set to %u uA\n",
+ data->usb_current_limit_ua);
+
+ return 0;
+}
+
+static int max8903_set_property(struct power_supply *psy,
+ enum power_supply_property psp,
+ const union power_supply_propval *val)
+{
+ struct max8903_data *data = power_supply_get_drvdata(psy);
+ int ret;
+
+ switch (psp) {
+ case POWER_SUPPLY_PROP_INPUT_CURRENT_LIMIT:
+ /*
+ * Hold source_lock across the source check and the
+ * resulting hardware write so the IRQ handler cannot
+ * flip ta_in/usb_in between them and have us program the
+ * limit for a source that has just gone offline.
+ */
+ mutex_lock(&data->source_lock);
+ if (data->ta_in && data->dc_current_limit_gpios)
+ ret = max8903_set_dc_current_limit(data, val->intval);
+ else if (data->usb_in && data->usb_current_limit_gpio)
+ ret = max8903_set_usb_current_limit(data, val->intval);
+ else
+ ret = -EINVAL;
+ mutex_unlock(&data->source_lock);
+ return ret;
+ default:
+ return -EINVAL;
+ }
+}
+
+static int max8903_property_is_writeable(struct power_supply *psy,
+ enum power_supply_property psp)
+{
+ struct max8903_data *data = power_supply_get_drvdata(psy);
+
+ switch (psp) {
+ case POWER_SUPPLY_PROP_INPUT_CURRENT_LIMIT:
+ return data->dc_current_limit_gpios ||
+ data->usb_current_limit_gpio;
+ default:
+ return 0;
+ }
+}
+
static irqreturn_t max8903_dcin(int irq, void *_data)
{
struct max8903_data *data = _data;
@@ -91,12 +272,21 @@ static irqreturn_t max8903_dcin(int irq, void *_data)
* library as the line should be flagged GPIO_ACTIVE_LOW in the device
* tree.
*/
+ /*
+ * Sample the line under source_lock so a concurrent
+ * max8903_set_property() observes either the old or the new
+ * state consistently, never a torn read where the lock is held
+ * but the cached flag is about to be updated.
+ */
+ mutex_lock(&data->source_lock);
ta_in = gpiod_get_value(data->dok);
-
- if (ta_in == data->ta_in)
+ if (ta_in == data->ta_in) {
+ mutex_unlock(&data->source_lock);
return IRQ_HANDLED;
+ }
data->ta_in = ta_in;
+ mutex_unlock(&data->source_lock);
/* Set Current-Limit-Mode 1:DC 0:USB */
if (data->dcm)
@@ -150,12 +340,16 @@ static irqreturn_t max8903_usbin(int irq, void *_data)
* library as the line should be flagged GPIO_ACTIVE_LOW in the device
* tree.
*/
+ /* See ta_in handler: sample the line under the lock. */
+ mutex_lock(&data->source_lock);
usb_in = gpiod_get_value(data->uok);
-
- if (usb_in == data->usb_in)
+ if (usb_in == data->usb_in) {
+ mutex_unlock(&data->source_lock);
return IRQ_HANDLED;
+ }
data->usb_in = usb_in;
+ mutex_unlock(&data->source_lock);
/* Do not touch Current-Limit-Mode */
@@ -221,6 +415,148 @@ static irqreturn_t max8903_fault(int irq, void *_data)
return IRQ_HANDLED;
}
+static int max8903_parse_dc_current_limit(struct platform_device *pdev,
+ struct max8903_data *data)
+{
+ struct device *dev = &pdev->dev;
+ int ret, i, map_size;
+ u32 *map;
+
+ data->dc_current_limit_gpios = devm_gpiod_get_array_optional(dev,
+ "dc-current-limit", GPIOD_OUT_LOW);
+ if (IS_ERR(data->dc_current_limit_gpios))
+ return dev_err_probe(dev, PTR_ERR(data->dc_current_limit_gpios),
+ "failed to get DC current limit GPIOs");
+
+ if (!data->dc_current_limit_gpios)
+ return 0; /* Optional feature not present */
+
+ /* Parse mapping: pairs of (current_ua, gpio_value) */
+ map_size = device_property_count_u32(dev, "dc-current-limit-mapping");
+ if (map_size <= 0 || map_size % 2) {
+ dev_err(dev, "invalid dc-current-limit-mapping\n");
+ return -EINVAL;
+ }
+
+ map = devm_kcalloc(dev, map_size, sizeof(*map), GFP_KERNEL);
+ if (!map)
+ return -ENOMEM;
+
+ ret = device_property_read_u32_array(dev, "dc-current-limit-mapping",
+ map, map_size);
+ if (ret) {
+ dev_err(dev, "failed to read dc-current-limit-mapping\n");
+ return ret;
+ }
+
+ data->dc_current_limit_map_size = map_size / 2;
+ data->dc_current_limit_map = devm_kcalloc(dev,
+ data->dc_current_limit_map_size,
+ sizeof(*data->dc_current_limit_map),
+ GFP_KERNEL);
+ if (!data->dc_current_limit_map)
+ return -ENOMEM;
+
+ for (i = 0; i < data->dc_current_limit_map_size; i++) {
+ u32 gpio_value = map[i * 2 + 1];
+
+ /*
+ * gpio_value is the bitmap programmed across the
+ * dc-current-limit GPIOs, so it cannot represent more
+ * bits than the GPIO array width. A larger value would
+ * be silently truncated by gpiod_set_array_value() and
+ * select the wrong limit; reject it at parse time so
+ * the bogus DT is visible to the integrator.
+ */
+ if (gpio_value >= BIT(data->dc_current_limit_gpios->ndescs)) {
+ dev_err(dev,
+ "dc-current-limit-mapping entry %d: gpio_value 0x%x exceeds %u-GPIO range\n",
+ i, gpio_value,
+ data->dc_current_limit_gpios->ndescs);
+ return -EINVAL;
+ }
+ data->dc_current_limit_map[i].limit_ua = map[i * 2];
+ data->dc_current_limit_map[i].gpio_value = gpio_value;
+ }
+
+ /*
+ * devm_gpiod_get_array_optional() above asked for GPIOD_OUT_LOW,
+ * so the hardware mux starts at gpio_value 0. Require the DT
+ * mapping to include a gpio_value=0 entry so the software
+ * current-limit state has a definite initial value matching the
+ * hardware. Without this entry we would have to guess and the
+ * reported INPUT_CURRENT_LIMIT could disagree with what the
+ * mux is actually wired to until a set_property write picks a
+ * real value.
+ */
+ for (i = 0; i < data->dc_current_limit_map_size; i++)
+ if (data->dc_current_limit_map[i].gpio_value == 0)
+ break;
+ if (i == data->dc_current_limit_map_size) {
+ dev_err(dev,
+ "dc-current-limit-mapping must include a gpio_value=0 entry to describe the boot-time mux state\n");
+ return -EINVAL;
+ }
+ data->dc_current_limit_ua = data->dc_current_limit_map[i].limit_ua;
+
+ dev_dbg(dev, "DC current limit control: %d levels available, initial %u uA\n",
+ data->dc_current_limit_map_size, data->dc_current_limit_ua);
+
+ return 0;
+}
+
+static int max8903_parse_usb_current_limit(struct platform_device *pdev,
+ struct max8903_data *data)
+{
+ struct device *dev = &pdev->dev;
+ u32 limits[2];
+ int ret;
+
+ data->usb_current_limit_gpio = devm_gpiod_get_optional(dev,
+ "usb-current-limit", GPIOD_OUT_LOW);
+ if (IS_ERR(data->usb_current_limit_gpio))
+ return dev_err_probe(dev, PTR_ERR(data->usb_current_limit_gpio),
+ "failed to get USB current limit GPIO");
+
+ if (!data->usb_current_limit_gpio)
+ return 0; /* Optional feature not present */
+
+ /* Parse [low_ua, high_ua] values, default to USB spec values */
+ ret = device_property_read_u32_array(dev, "usb-current-limit-values",
+ limits, 2);
+ if (ret) {
+ /* Default to USB spec values */
+ data->usb_current_limit_low_ua = 100000; /* 100mA */
+ data->usb_current_limit_high_ua = 500000; /* 500mA */
+ } else {
+ data->usb_current_limit_low_ua = limits[0];
+ data->usb_current_limit_high_ua = limits[1];
+ }
+
+ /*
+ * max8903_set_usb_current_limit() picks the highest cap that
+ * doesn't exceed the request by checking >=high first then
+ * >=low; that policy only works when high > low. Reject DTs
+ * that hand the property in the wrong order rather than
+ * silently program a sub-optimal current limit.
+ */
+ if (data->usb_current_limit_high_ua <= data->usb_current_limit_low_ua) {
+ dev_err(dev,
+ "usb-current-limit-values must be [low, high] with high > low (got low=%u uA, high=%u uA)\n",
+ data->usb_current_limit_low_ua,
+ data->usb_current_limit_high_ua);
+ return -EINVAL;
+ }
+
+ /* Start at low current for safety */
+ data->usb_current_limit_ua = data->usb_current_limit_low_ua;
+
+ dev_dbg(dev, "USB current limit control: %u/%u uA\n",
+ data->usb_current_limit_low_ua, data->usb_current_limit_high_ua);
+
+ return 0;
+}
+
static int max8903_setup_gpios(struct platform_device *pdev)
{
struct max8903_data *data = platform_get_drvdata(pdev);
@@ -335,17 +671,28 @@ static int max8903_probe(struct platform_device *pdev)
return -ENOMEM;
data->dev = dev;
+ mutex_init(&data->source_lock);
platform_set_drvdata(pdev, data);
ret = max8903_setup_gpios(pdev);
if (ret)
return ret;
+ ret = max8903_parse_dc_current_limit(pdev, data);
+ if (ret)
+ return ret;
+
+ ret = max8903_parse_usb_current_limit(pdev, data);
+ if (ret)
+ return ret;
+
data->psy_desc.name = "max8903_charger";
data->psy_desc.type = (data->ta_in) ? POWER_SUPPLY_TYPE_MAINS :
((data->usb_in) ? POWER_SUPPLY_TYPE_USB :
POWER_SUPPLY_TYPE_BATTERY);
data->psy_desc.get_property = max8903_get_property;
+ data->psy_desc.set_property = max8903_set_property;
+ data->psy_desc.property_is_writeable = max8903_property_is_writeable;
data->psy_desc.properties = max8903_charger_props;
data->psy_desc.num_properties = ARRAY_SIZE(max8903_charger_props);
--
2.43.0
^ permalink raw reply related [flat|nested] 3+ messages in thread