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authorHans de Goede <hdegoede@redhat.com>2020-04-28 20:29:18 +0300
committerJonathan Cameron <Jonathan.Cameron@huawei.com>2020-05-10 12:43:03 +0300
commitc1e62062ff5477f3cd40e956fb1c18808cc894a4 (patch)
treeea0ab22769340936627146fe8877c2f92edd533f /drivers/iio
parentb885d0fa6790b8b2c8502dc93fed27ce85e68922 (diff)
downloadlinux-c1e62062ff5477f3cd40e956fb1c18808cc894a4.tar.xz
iio: light: cm32181: Handle CM3218 ACPI devices with 2 I2C resources
Some ACPI systems list 2 I2C resources for the CM3218 sensor. On these systems the first I2cSerialBus ACPI-resource points to the SMBus Alert Response Address (ARA, 0x0c) and the second I2cSerialBus ACPI-resource points to the actual CM3218 sensor address: Method (_CRS, 0, NotSerialized) // _CRS: Current Resource Settings { Name (SBUF, ResourceTemplate () { I2cSerialBusV2 (0x000C, ControllerInitiated, 0x00061A80, AddressingMode7Bit, "\\_SB.I2C3", 0x00, ResourceConsumer, , Exclusive, ) I2cSerialBusV2 (0x0048, ControllerInitiated, 0x00061A80, AddressingMode7Bit, "\\_SB.I2C3", 0x00, ResourceConsumer, , Exclusive, ) Interrupt (ResourceConsumer, Level, ActiveHigh, Exclusive, ,, ) { 0x00000033, } }) Return (SBUF) /* \_SB_.I2C3.ALSD._CRS.SBUF */ } Detect this and take the following step to deal with it: 1. When a SMBus Alert capable sensor has an Alert asserted, it will not respond on its actual I2C address. Read a byte from the ARA to clear any pending Alerts. 2. Create a "dummy" client for the actual I2C address and use that client to communicate with the sensor. Signed-off-by: Hans de Goede <hdegoede@redhat.com> Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Diffstat (limited to 'drivers/iio')
-rw-r--r--drivers/iio/light/cm32181.c22
1 files changed, 22 insertions, 0 deletions
diff --git a/drivers/iio/light/cm32181.c b/drivers/iio/light/cm32181.c
index a02ec59f2a94..84a5e3927558 100644
--- a/drivers/iio/light/cm32181.c
+++ b/drivers/iio/light/cm32181.c
@@ -52,6 +52,8 @@
#define CM32181_CALIBSCALE_RESOLUTION 1000
#define MLUX_PER_LUX 1000
+#define SMBUS_ALERT_RESPONSE_ADDRESS 0x0c
+
static const u8 cm32181_reg[CM32181_CONF_REG_NUM] = {
CM32181_REG_ADDR_CMD,
};
@@ -336,6 +338,26 @@ static int cm32181_probe(struct i2c_client *client)
if (!indio_dev)
return -ENOMEM;
+ /*
+ * Some ACPI systems list 2 I2C resources for the CM3218 sensor, the
+ * SMBus Alert Response Address (ARA, 0x0c) and the actual I2C address.
+ * Detect this and take the following step to deal with it:
+ * 1. When a SMBus Alert capable sensor has an Alert asserted, it will
+ * not respond on its actual I2C address. Read a byte from the ARA
+ * to clear any pending Alerts.
+ * 2. Create a "dummy" client for the actual I2C address and
+ * use that client to communicate with the sensor.
+ */
+ if (ACPI_HANDLE(dev) && client->addr == SMBUS_ALERT_RESPONSE_ADDRESS) {
+ struct i2c_board_info board_info = { .type = "dummy" };
+
+ i2c_smbus_read_byte(client);
+
+ client = i2c_acpi_new_device(dev, 1, &board_info);
+ if (IS_ERR(client))
+ return PTR_ERR(client);
+ }
+
cm32181 = iio_priv(indio_dev);
cm32181->client = client;