From 9fdf1d03331623e377d8445e600b09111259a608 Mon Sep 17 00:00:00 2001
From: Victor Duicu <victor.duicu@microchip.com>
Date: Fri, 15 Nov 2024 15:34:36 +0200
Subject: [PATCH] iio: adc: pac1921: Add ACPI support to Microchip pac1921
This patch implements ACPI support to Microchip pac1921.
The driver can read the shunt resistor value and label from the ACPI table.
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Acked-by: Matteo Martelli <matteomartelli3@gmail.com>
Signed-off-by: Victor Duicu <victor.duicu@microchip.com>
Link: https://patch.msgid.link/20241115133436.13204-1-victor.duicu@microchip.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
---
drivers/iio/adc/pac1921.c | 93 ++++++++++++++++++++++++++++++++++++---
1 file changed, 87 insertions(+), 6 deletions(-)
diff --git a/drivers/iio/adc/pac1921.c b/drivers/iio/adc/pac1921.c
index b0f6727cfe383..9f7b3d58549d5 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,
--
GitLab