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power: supply: max8903: add DC and USB input current-limit GPIO controls

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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). The IUSB
    pin is silicon-fixed per the MAX8903 datasheet Pin Description:
    logic-low selects 100 mA, logic-high selects 500 mA. The two
    values are encoded as MAX8903_USB_CURRENT_LIMIT_{LOW,HIGH}_UA
    #defines with the datasheet quote in a header comment. The
    requested limit picks HIGH if it can absorb 500 mA, else LOW,
    else returns -EINVAL rather than silently programming a higher
    current that would violate the system power budget. Mirroring
    the DC-priority policy in the get path: when ta_in is asserted
    the part draws from DC regardless of USB state, so the set path
    only routes to USB when DC is not online.

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 DOK/UOK IRQ
handlers hold source_lock across the full read-modify-evaluate block
(line sampling, ta_in/usb_in update, dcm/cen GPIO writes, psy type
update) so the cen enable calculation reads a stable other-source
flag rather than racing with the peer IRQ. 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. ndescs is also bounded to
< BITS_PER_TYPE(u32) to keep BIT(ndescs) well-defined on 32-bit.
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.

Negative INPUT_CURRENT_LIMIT requests are rejected at the
set_property entry: val->intval is signed, the set_*_current_limit()
helpers take a u32, and a negative cast would silently widen to a
huge unsigned value, bypass the upper-bound guard and program the
maximum permitted current.

Signed-off-by: Herman van Hazendonk <github.com@herrie.org>
Link: https://patch.msgid.link/20260605-submit-power-max8903-dc-limit-v2-2-0c5396e98f14@herrie.org
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>
This commit is contained in:
Herman van Hazendonk 2026-06-05 11:18:13 +02:00 committed by Sebastian Reichel
parent 353438b310
commit 8284146600
1 changed files with 398 additions and 17 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

415
drivers/power/supply/max8903_charger.c
View File

@ -9,11 +9,29 @@
#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>
/*
* IUSB pin: hardcoded by silicon to 100 mA (low) / 500 mA (high).
* MAX8903A/B/C/D/E/F/G/H/I datasheet, "Pin Description" table:
* "USB Current-Limit Set Input. Drive IUSB logic-low to set the
* USB current limit to 100mA. Drive IUSB logic-high to set the
* USB current limit to 500mA."
* Not a board parameter - never DT-configurable.
*/
#define MAX8903_USB_CURRENT_LIMIT_LOW_UA 100000
#define MAX8903_USB_CURRENT_LIMIT_HIGH_UA 500000
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 +49,25 @@ 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_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 +77,7 @@ 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 +85,24 @@ 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 +111,42 @@ 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:
/*
* Hardware prioritises DC over USB - when ta_in is asserted
* the part draws from the DC input regardless of USB state.
* So always report the DC-side limit when DC is online, and
* refuse rather than silently fall back to the USB cap if
* the DC GPIOs are not configured - that would mis-describe
* the active source. Same policy applies in the set path.
*/
if (ta_in) {
if (!data->dc_current_limit_gpios)
return -ENODATA;
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 +155,144 @@ 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;
/*
* The mapping's gpio_value fits in the lowest ndescs bits of one
* unsigned long (parse_dc_current_limit enforces ndescs < 32 and
* gpio_value < BIT(ndescs)); a single-word bitmap is sufficient
* on both 32- and 64-bit builds. Don't use bitmap_from_arr32() -
* that macro reinterprets its source pointer as unsigned long on
* 64-bit and would read past the on-stack u32.
*/
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;
bitmap_zero(values, BITS_PER_TYPE(u32));
values[0] = data->dc_current_limit_map[best_idx].gpio_value;
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;
/*
* IUSB is a single-bit input with two silicon-fixed settings;
* pick HIGH (500 mA) iff the caller's cap can absorb it, else
* LOW (100 mA), else refuse rather than program a higher current
* than the request allows.
*/
if (limit_ua >= MAX8903_USB_CURRENT_LIMIT_HIGH_UA) {
selected = MAX8903_USB_CURRENT_LIMIT_HIGH_UA;
gpio_val = 1;
} else if (limit_ua >= MAX8903_USB_CURRENT_LIMIT_LOW_UA) {
selected = MAX8903_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:
/*
* val->intval is signed; the set_*_current_limit() helpers
* take a u32. Reject negatives explicitly so a negative
* request cannot widen into a huge unsigned value, bypass
* the "limit <= cap" bounds check inside the helper, and
* silently program the maximum permitted current.
*/
if (val->intval < 0)
return -EINVAL;
/*
* 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. Mirror
* the DC-priority policy of the get path: if DC is online
* route to the DC helper (refuse if DC GPIOs aren't
* configured) rather than fall through to USB.
*/
mutex_lock(&data->source_lock);
if (data->ta_in)
ret = data->dc_current_limit_gpios ?
max8903_set_dc_current_limit(data, val->intval) :
-ENODEV;
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;
@ -91,10 +306,21 @@ static irqreturn_t max8903_dcin(int irq, void *_data)
* library as the line should be flagged GPIO_ACTIVE_LOW in the device
* tree.
*/
/*
* Hold source_lock across the full read-modify-evaluate block:
* - so a concurrent max8903_set_property() sees a consistent
* state (lock release would otherwise expose a window where
* data->ta_in is updated but the cen/dcm writes still pend);
* - so the cen enable calculation reads a stable data->usb_in
* rather than racing with max8903_usbin() and writing the
* wrong enable state.
*/
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;
@ -119,9 +345,6 @@ static irqreturn_t max8903_dcin(int irq, void *_data)
gpiod_set_value(data->cen, val);
}
dev_dbg(data->dev, "TA(DC-IN) Charger %s.\n", ta_in ?
"Connected" : "Disconnected");
old_type = data->psy_desc.type;
if (data->ta_in)
@ -130,6 +353,10 @@ static irqreturn_t max8903_dcin(int irq, void *_data)
data->psy_desc.type = POWER_SUPPLY_TYPE_USB;
else
data->psy_desc.type = POWER_SUPPLY_TYPE_BATTERY;
mutex_unlock(&data->source_lock);
dev_dbg(data->dev, "TA(DC-IN) Charger %s.\n", ta_in ?
"Connected" : "Disconnected");
if (old_type != data->psy_desc.type)
power_supply_changed(data->psy);
@ -150,10 +377,13 @@ static irqreturn_t max8903_usbin(int irq, void *_data)
* library as the line should be flagged GPIO_ACTIVE_LOW in the device
* tree.
*/
/* See max8903_dcin(): hold the lock across the full update. */
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;
@ -176,9 +406,6 @@ static irqreturn_t max8903_usbin(int irq, void *_data)
gpiod_set_value(data->cen, val);
}
dev_dbg(data->dev, "USB Charger %s.\n", usb_in ?
"Connected" : "Disconnected");
old_type = data->psy_desc.type;
if (data->ta_in)
@ -187,6 +414,10 @@ static irqreturn_t max8903_usbin(int irq, void *_data)
data->psy_desc.type = POWER_SUPPLY_TYPE_USB;
else
data->psy_desc.type = POWER_SUPPLY_TYPE_BATTERY;
mutex_unlock(&data->source_lock);
dev_dbg(data->dev, "USB Charger %s.\n", usb_in ?
"Connected" : "Disconnected");
if (old_type != data->psy_desc.type)
power_supply_changed(data->psy);
@ -221,6 +452,145 @@ 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 */
/*
* gpio_value entries below are bit patterns indexed into the
* dc-current-limit GPIO array. The driver represents them in
* a single unsigned long for gpiod_set_array_value_cansleep(),
* and BIT(ndescs) further down assumes ndescs fits in a u32
* shift; reject pathological DTs at parse time instead of
* relying on undefined-behaviour-free dtschema. The binding
* already caps maxItems at 4 so this is purely defensive.
*/
if (data->dc_current_limit_gpios->ndescs >= BITS_PER_TYPE(u32)) {
dev_err(dev, "dc-current-limit-gpios: %u GPIOs exceeds %u-bit cap\n",
data->dc_current_limit_gpios->ndescs,
(unsigned int)BITS_PER_TYPE(u32));
return -EINVAL;
}
/* 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[] is a scratch buffer used only inside this function to
* read the property and unpack it into data->dc_current_limit_map.
* Use a plain kmalloc + kfree rather than devm_*: there is no
* reason to keep the raw mirror around for the lifetime of the
* device.
*/
map = kmalloc_array(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");
kfree(map);
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) {
kfree(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);
kfree(map);
return -EINVAL;
}
data->dc_current_limit_map[i].limit_ua = map[i * 2];
data->dc_current_limit_map[i].gpio_value = gpio_value;
}
kfree(map);
/*
* 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;
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 */
/* Start at low current (IUSB low = 100 mA) for safety */
data->usb_current_limit_ua = MAX8903_USB_CURRENT_LIMIT_LOW_UA;
return 0;
}
static int max8903_setup_gpios(struct platform_device *pdev)
{
struct max8903_data *data = platform_get_drvdata(pdev);
@ -335,17 +705,28 @@ 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);