From: Victor Duicu <victor.duicu@xxxxxxxxxxxxx>
This patch implements ACPI support to Microchip pac1921.
The driver can read shunt resistor value and label from ACPI table.
Signed-off-by: Victor Duicu <victor.duicu@xxxxxxxxxxxxx>
---
The patch was tested on minnowboard and sama5.
Differences related to previous versions:
v6:
- set maximum acceptable value of shunt resistor to INT_MAX UOHMS
in devicetree, ACPI table and user input.
- in pac1921_match_acpi_device remove temp variable.
v5:
- set maximum acceptable value of shunt resistor to 2KOHM in devicetree,
ACPI table and user input. The chosen value is lesser than INT_MAX,
which is about 2.1KOHM.
- in pac1921_match_acpi_device and pac1921_parse_of_fw change to only
read 32b values for resistor shunt.
v4:
- change name of pac1921_shunt_is_valid to pac1921_shunt_is_invalid.
- fix coding style.
- in pac1921_parse_of_fw change back to device_property_read_u32.
v3:
- simplify and make inline function pac1921_shunt_is_valid. Make argument u64.
- fix link to DSM documentation.
- in pac1921_match_acpi_device and pac1921_parse_of_fw, the shunt value is
read as u64.
- in pac1921_parse_of_fw remove code for reading label value from
devicetree.
- in pac1921_write_shunt_resistor cast the multiply result to u64 in order
to fix overflow.
v2:
- remove name variable from priv. Driver reads label attribute with
sysfs.
- define pac1921_shunt_is_valid function.
- move default assignments in pac1921_probe to original position.
- roll back coding style changes.
- add documentation for DSM(the linked document was used as reference).
- remove acpi_match_device in pac1921_match_acpi_device.
- remove unnecessary null assignment and comment.
- change name of function pac1921_match_of_device to
pac1921_parse_of_fw.
v1:
- initial version for review.
drivers/iio/adc/pac1921.c | 106 +++++++++++++++++++++++++++++++++-----
1 file changed, 93 insertions(+), 13 deletions(-)
diff --git a/drivers/iio/adc/pac1921.c b/drivers/iio/adc/pac1921.c
index a96fae546bc1..cbbb3c1525c1 100644
--- a/drivers/iio/adc/pac1921.c
+++ b/drivers/iio/adc/pac1921.c
@@ -67,6 +67,12 @@ 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
+#define PAC1921_DSM_UUID "f7bb9932-86ee-4516-a236-7a7a742e55cb"
+/* The maximum accepted value of shunt_resistor in UOHMS <= INT_MAX */
+#define PAC1921_MAX_SHUNT_VALUE_OHMS 2147
+
/*
* Pre-computed scale factors for BUS voltage
* format: IIO_VAL_INT_PLUS_NANO
@@ -204,6 +210,11 @@ struct pac1921_priv {
} scan;
};
+static inline bool pac1921_shunt_is_invalid(u32 shunt_val)
+{
+ return (shunt_val == 0 || shunt_val > INT_MAX);
+}
+
/*
* Check if first integration after configuration update has completed.
*
@@ -781,7 +792,7 @@ 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;
@@ -792,8 +803,12 @@ static ssize_t pac1921_write_shunt_resistor(struct iio_dev *indio_dev,
if (ret)
return ret;
+ /* This check is to ensure val * MICRO won't overflow */
+ if (val < 0 || val > PAC1921_MAX_SHUNT_VALUE_OHMS)
+ return -EINVAL;
+
rshunt_uohm = val * MICRO + val_fract;
- if (rshunt_uohm == 0 || rshunt_uohm > INT_MAX)
+ if (pac1921_shunt_is_invalid(rshunt_uohm))
return -EINVAL;
guard(mutex)(&priv->lock);
@@ -1150,6 +1165,69 @@ 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 i2c_client *client, struct pac1921_priv *priv,
+ struct iio_dev *indio_dev)
+{
+ acpi_handle handle;
+ union acpi_object *rez;
+ guid_t guid;
+ char *label;
+
+ guid_parse(PAC1921_DSM_UUID, &guid);
+ handle = ACPI_HANDLE(&client->dev);
+
+ rez = acpi_evaluate_dsm(handle, &guid, 1, PAC1921_ACPI_GET_UOHMS_VALS, NULL);
+ if (!rez)
+ return dev_err_probe(&client->dev, -EINVAL,
+ "Could not read shunt from ACPI table\n");
+
+ priv->rshunt_uohm = rez->package.elements[0].integer.value;
+ ACPI_FREE(rez);
+
+ if (pac1921_shunt_is_invalid(priv->rshunt_uohm))
+ return dev_err_probe(&client->dev, -EINVAL, "Invalid shunt resistor\n");
+
+ pac1921_calc_current_scales(priv);
+
+ rez = acpi_evaluate_dsm(handle, &guid, 1, PAC1921_ACPI_GET_LABEL, NULL);
+ if (!rez)
+ return dev_err_probe(&client->dev, -EINVAL,
+ "Could not read label from ACPI table\n");
+
+ label = devm_kmemdup(&client->dev, rez->package.elements->string.pointer,
+ (size_t)rez->package.elements->string.length + 1,
+ GFP_KERNEL);
+ label[rez->package.elements->string.length] = '\0';
+ indio_dev->label = label;
+ ACPI_FREE(rez);
+
+ return 0;
+}
+
+static int pac1921_parse_of_fw(struct i2c_client *client, struct pac1921_priv *priv)
+{
+ int ret;
+ struct device *dev = &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");
+
+ if (pac1921_shunt_is_invalid(priv->rshunt_uohm))
+ return dev_err_probe(dev, -EINVAL, "Invalid shunt resistor: %u\n",
+ priv->rshunt_uohm);
+
+ pac1921_calc_current_scales(priv);
+
+ return 0;
+}
+
static int pac1921_probe(struct i2c_client *client)
{
struct device *dev = &client->dev;
@@ -1176,17 +1254,13 @@ 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 (ret)
- return dev_err_probe(dev, ret,
- "Cannot read shunt resistor property\n");
- if (priv->rshunt_uohm == 0 || priv->rshunt_uohm > INT_MAX)
- return dev_err_probe(dev, -EINVAL,
- "Invalid shunt resistor: %u\n",
- priv->rshunt_uohm);
-
- pac1921_calc_current_scales(priv);
+ if (ACPI_HANDLE(&client->dev))
+ ret = pac1921_match_acpi_device(client, priv, indio_dev);
+ else
+ ret = pac1921_parse_of_fw(client, priv);
+ if (ret < 0)
+ return dev_err_probe(&client->dev, ret,
+ "parameter parsing error\n");
priv->vdd = devm_regulator_get(dev, "vdd");
if (IS_ERR(priv->vdd))
@@ -1243,11 +1317,17 @@ 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,
base-commit: 185a947e0ef928226f99c05fc973cde872806aa1
--
2.43.0
