diff --git a/drivers/iio/adc/pac1921.c b/drivers/iio/adc/pac1921.c index b0f6727cfe3835de5ac962e6221f39fe1d3acfb8..9f7b3d58549d5cdab24880a90b7a57a0554e7a90 100644 --- a/drivers/iio/adc/pac1921.c +++ b/drivers/iio/adc/pac1921.c @@ -12,6 +12,7 @@ #include <linux/iio/iio.h> #include <linux/iio/trigger_consumer.h> #include <linux/iio/triggered_buffer.h> +#include <linux/limits.h> #include <linux/regmap.h> #include <linux/units.h> @@ -67,6 +68,14 @@ enum pac1921_mxsl { #define PAC1921_DEFAULT_DI_GAIN 0 /* 2^(value): 1x gain (HW default) */ #define PAC1921_DEFAULT_NUM_SAMPLES 0 /* 2^(value): 1 sample (HW default) */ +#define PAC1921_ACPI_GET_uOHMS_VALS 0 +#define PAC1921_ACPI_GET_LABEL 1 + +/* f7bb9932-86ee-4516-a236-7a7a742e55cb */ +static const guid_t pac1921_guid = + GUID_INIT(0xf7bb9932, 0x86ee, 0x4516, 0xa2, + 0x36, 0x7a, 0x7a, 0x74, 0x2e, 0x55, 0xcb); + /* * Pre-computed scale factors for BUS voltage * format: IIO_VAL_INT_PLUS_NANO @@ -782,7 +791,7 @@ static ssize_t pac1921_write_shunt_resistor(struct iio_dev *indio_dev, const char *buf, size_t len) { struct pac1921_priv *priv = iio_priv(indio_dev); - u64 rshunt_uohm; + u32 rshunt_uohm; int val, val_fract; int ret; @@ -793,10 +802,17 @@ static ssize_t pac1921_write_shunt_resistor(struct iio_dev *indio_dev, if (ret) return ret; - rshunt_uohm = val * MICRO + val_fract; - if (rshunt_uohm == 0 || rshunt_uohm > INT_MAX) + /* + * This check validates the shunt is not zero and does not surpass + * INT_MAX. The check is done before calculating in order to avoid + * val * MICRO overflowing. + */ + if ((!val && !val_fract) || val > INT_MAX / MICRO || + (val == INT_MAX / MICRO && val_fract > INT_MAX % MICRO)) return -EINVAL; + rshunt_uohm = val * MICRO + val_fract; + guard(mutex)(&priv->lock); priv->rshunt_uohm = rshunt_uohm; @@ -1151,6 +1167,61 @@ static void pac1921_regulator_disable(void *data) regulator_disable(regulator); } +/* + * Documentation related to the ACPI device definition + * https://ww1.microchip.com/downloads/aemDocuments/documents/OTH/ApplicationNotes/ApplicationNotes/PAC193X-Integration-Notes-for-Microsoft-Windows-10-and-Windows-11-Driver-Support-DS00002534.pdf + */ +static int pac1921_match_acpi_device(struct iio_dev *indio_dev) +{ + acpi_handle handle; + union acpi_object *status; + char *label; + struct pac1921_priv *priv = iio_priv(indio_dev); + struct device *dev = &priv->client->dev; + + handle = ACPI_HANDLE(dev); + + status = acpi_evaluate_dsm(handle, &pac1921_guid, 1, + PAC1921_ACPI_GET_uOHMS_VALS, NULL); + if (!status) + return dev_err_probe(dev, -EINVAL, + "Could not read shunt from ACPI table\n"); + + priv->rshunt_uohm = status->package.elements[0].integer.value; + ACPI_FREE(status); + + status = acpi_evaluate_dsm(handle, &pac1921_guid, 1, + PAC1921_ACPI_GET_LABEL, NULL); + if (!status) + return dev_err_probe(dev, -EINVAL, + "Could not read label from ACPI table\n"); + + label = devm_kstrdup(dev, status->package.elements[0].string.pointer, + GFP_KERNEL); + if (!label) + return -ENOMEM; + + indio_dev->label = label; + ACPI_FREE(status); + + return 0; +} + +static int pac1921_parse_of_fw(struct iio_dev *indio_dev) +{ + int ret; + struct pac1921_priv *priv = iio_priv(indio_dev); + struct device *dev = &priv->client->dev; + + ret = device_property_read_u32(dev, "shunt-resistor-micro-ohms", + &priv->rshunt_uohm); + if (ret) + return dev_err_probe(dev, ret, + "Cannot read shunt resistor property\n"); + + return 0; +} + static int pac1921_probe(struct i2c_client *client) { struct device *dev = &client->dev; @@ -1179,11 +1250,14 @@ static int pac1921_probe(struct i2c_client *client) priv->di_gain = PAC1921_DEFAULT_DI_GAIN; priv->n_samples = PAC1921_DEFAULT_NUM_SAMPLES; - ret = device_property_read_u32(dev, "shunt-resistor-micro-ohms", - &priv->rshunt_uohm); + if (is_acpi_device_node(dev->fwnode)) + ret = pac1921_match_acpi_device(indio_dev); + else + ret = pac1921_parse_of_fw(indio_dev); if (ret) return dev_err_probe(dev, ret, - "Cannot read shunt resistor property\n"); + "Parameter parsing error\n"); + if (priv->rshunt_uohm == 0 || priv->rshunt_uohm > INT_MAX) return dev_err_probe(dev, -EINVAL, "Invalid shunt resistor: %u\n", @@ -1246,11 +1320,18 @@ static const struct of_device_id pac1921_of_match[] = { }; MODULE_DEVICE_TABLE(of, pac1921_of_match); +static const struct acpi_device_id pac1921_acpi_match[] = { + { "MCHP1921" }, + { } +}; +MODULE_DEVICE_TABLE(acpi, pac1921_acpi_match); + static struct i2c_driver pac1921_driver = { .driver = { .name = "pac1921", .pm = pm_sleep_ptr(&pac1921_pm_ops), .of_match_table = pac1921_of_match, + .acpi_match_table = pac1921_acpi_match, }, .probe = pac1921_probe, .id_table = pac1921_id,