From: Hans de Goede <hdegoede@redhat.com>
To: "Rafael J . Wysocki" <rjw@rjwysocki.net>,
Len Brown <lenb@kernel.org>, Darren Hart <dvhart@infradead.org>,
Andy Shevchenko <andy@infradead.org>,
Kevin Tsai <ktsai@capellamicro.com>,
Jonathan Cameron <jic23@kernel.org>
Cc: Hans de Goede <hdegoede@redhat.com>,
linux-acpi@vger.kernel.org, platform-driver-x86@vger.kernel.org,
linux-kernel@vger.kernel.org, Hartmut Knaack <knaack.h@gmx.de>,
Lars-Peter Clausen <lars@metafoo.de>,
Peter Meerwald-Stadler <pmeerw@pmeerw.net>,
linux-iio@vger.kernel.org
Subject: [PATCH 3/8] iio: light: cm32181: Handle ACPI instantiating a cm32181 client on the SMBus ARA
Date: Sun, 26 Apr 2020 13:02:51 +0200 [thread overview]
Message-ID: <20200426110256.218186-3-hdegoede@redhat.com> (raw)
In-Reply-To: <20200426110256.218186-1-hdegoede@redhat.com>
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.
From the ACPI/x86 side devices with more then 1 I2cSerialBus ACPI-resource
are handled by the drivers/platform/x86/i2c-multi-instantiate.c code.
This code will instantiate "cm32181" i2c_client-s for both resources.
Add a check to cm32181_probe() for the client's address being the ARA
address, and in that case fail the probe with -ENODEV.
On these ACPI systems the sensor may have a SMBus Alert asserted at boot,
if this is the case the sensor will not respond to any i2c_transfers on
its actual address until we read from the ARA register to clear the Alert.
Therefor we must (try to) read a byte from the client with the ARA
register, before returning -ENODEV, so that we clear the Alert and when
we get called again for the client instantiated for the second
I2cSerialBus ACPI-resource the sensor will respond to our i2c-transfers.
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
---
drivers/iio/light/cm32181.c | 16 ++++++++++++++++
1 file changed, 16 insertions(+)
diff --git a/drivers/iio/light/cm32181.c b/drivers/iio/light/cm32181.c
index fd371b36c7b3..e8be20d3902c 100644
--- a/drivers/iio/light/cm32181.c
+++ b/drivers/iio/light/cm32181.c
@@ -51,6 +51,8 @@
#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,
};
@@ -333,6 +335,20 @@ static int cm32181_probe(struct i2c_client *client,
struct iio_dev *indio_dev;
int ret;
+ /*
+ * Some ACPI systems list 2 I2C resources for the CM3218 sensor, the
+ * SMBus Alert Response Address (ARA, 0x0c) and the actual I2C address.
+ * drivers/platform/x86/i2c-multi-instantiate.c instantiates "cm32181"
+ * i2c_client-s for both resources, ignore the ARA client.
+ * On these systems the sensor may have a SMBus Alert asserted at boot,
+ * in that case the ARA must be read to clear the Alert otherwise the
+ * sensor will not respond on its actual I2C address.
+ */
+ if (client->addr == SMBUS_ALERT_RESPONSE_ADDRESS) {
+ i2c_smbus_read_byte(client);
+ return -ENODEV;
+ }
+
indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*cm32181));
if (!indio_dev) {
dev_err(&client->dev, "devm_iio_device_alloc failed\n");
--
2.26.0
next prev parent reply other threads:[~2020-04-26 11:03 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-26 11:02 [PATCH 1/8] iio: light: cm32181: Add some extra register defines Hans de Goede
2020-04-26 11:02 ` [PATCH 2/8] iio: light: cm32181: Add support for the CM3218 Hans de Goede
2020-04-26 11:02 ` Hans de Goede [this message]
2020-04-26 17:43 ` [PATCH 3/8] iio: light: cm32181: Handle ACPI instantiating a cm32181 client on the SMBus ARA Andy Shevchenko
2020-04-26 11:02 ` [PATCH 4/8] iio: light: cm32181: Change reg_init to use a bitmap of which registers to init Hans de Goede
2020-04-26 17:44 ` Andy Shevchenko
2020-04-26 11:02 ` [PATCH 5/8] iio: light: cm32181: Use units of 1/100000th for calibscale and lux_per_bit Hans de Goede
2020-04-26 11:02 ` [PATCH 6/8] iio: light: cm32181: Make lux_per_bit and lux_per_bit_base_it runtime settings Hans de Goede
2020-04-26 11:02 ` [PATCH 7/8] iio: light: cm32181: Add support for parsing CPM0 and CPM1 ACPI tables Hans de Goede
2020-04-26 17:50 ` Andy Shevchenko
2020-04-27 15:31 ` Hans de Goede
2020-04-26 11:02 ` [PATCH 8/8] iio: light: cm32181: Fix integartion time typo Hans de Goede
2020-04-26 17:51 ` Andy Shevchenko
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20200426110256.218186-3-hdegoede@redhat.com \
--to=hdegoede@redhat.com \
--cc=andy@infradead.org \
--cc=dvhart@infradead.org \
--cc=jic23@kernel.org \
--cc=knaack.h@gmx.de \
--cc=ktsai@capellamicro.com \
--cc=lars@metafoo.de \
--cc=lenb@kernel.org \
--cc=linux-acpi@vger.kernel.org \
--cc=linux-iio@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=platform-driver-x86@vger.kernel.org \
--cc=pmeerw@pmeerw.net \
--cc=rjw@rjwysocki.net \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).