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Date: Thu, 26 Oct 2017 21:05:21 +0200 (CEST)
From: Peter Meerwald-Stadler <pmeerw@...erw.net>
To: Marc CAPDEVILLE <m.capdeville@...log.org>
cc: Kevin Tsai <ktsai@...ellamicro.com>,
Jonathan Cameron <jic23@...nel.org>,
Hartmut Knaack <knaack.h@....de>,
Lars-Peter Clausen <lars@...afoo.de>,
linux-iio@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] iio : Add cm3218 smbus ara and acpi support
> On asus T100, Capella cm3218 chip is implemented as ambiant light
> sensor. This chip expose an smbus ARA protocol device on standard
> address 0x0c. The chip is not functional before all alerts are
> acknowledged.
> On asus T100, this device is enumerated on ACPI bus and the description
> give tow I2C connection. The first is the connection to the ARA device
> and the second gives the real address of the device.
>
> So, on device probe,If the i2c address is the ARA address and the
> device is enumerated via acpi, we lookup for the real address in
> the ACPI resource list and change it in the client structure.
> if an interrupt resource is given, and only for cm3218 chip,
> we declare an smbus_alert device.
comments below; some are unrelated cleanups if you care...
> Signed-off-by: Marc CAPDEVILLE <m.capdeville@...log.org>
> ---
> v2 :
> - cm3218 support always build
> - Cleanup of unneeded #if statement
> - Beter identifying chip in platform device, acpi and of_device
>
> drivers/iio/light/cm32181.c | 165 +++++++++++++++++++++++++++++++++++++++++++-
> 1 file changed, 162 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/iio/light/cm32181.c b/drivers/iio/light/cm32181.c
> index d6fd0da..7bc97ff 100644
> --- a/drivers/iio/light/cm32181.c
> +++ b/drivers/iio/light/cm32181.c
> @@ -18,6 +18,9 @@
> #include <linux/iio/sysfs.h>
> #include <linux/iio/events.h>
> #include <linux/init.h>
> +#include <linux/i2c-smbus.h>
> +#include <linux/acpi.h>
> +#include <linux/of_device.h>
>
> /* Registers Address */
maybe better 'Register Addresses'
> #define CM32181_REG_ADDR_CMD 0x00
> @@ -47,6 +50,11 @@
> #define CM32181_CALIBSCALE_RESOLUTION 1000
> #define MLUX_PER_LUX 1000
CM32181_ prefix?
>
> +#define CM32181_ID 0x81
> +#define CM3218_ID 0x18
> +
> +#define CM3218_ARA_ADDR 0x0c
> +
> static const u8 cm32181_reg[CM32181_CONF_REG_NUM] = {
> CM32181_REG_ADDR_CMD,
> };
> @@ -57,6 +65,8 @@ static const int als_it_value[] = {25000, 50000, 100000, 200000, 400000,
cm32181_ prefix?
>
> struct cm32181_chip {
> struct i2c_client *client;
> + int chip_id;
> + struct i2c_client *ara;
> struct mutex lock;
> u16 conf_regs[CM32181_CONF_REG_NUM];
> int calibscale;
> @@ -81,7 +91,7 @@ static int cm32181_reg_init(struct cm32181_chip *cm32181)
> return ret;
>
> /* check device ID */
> - if ((ret & 0xFF) != 0x81)
> + if ((ret & 0xFF) != cm32181->chip_id)
> return -ENODEV;
>
> /* Default Values */
> @@ -298,12 +308,81 @@ static const struct iio_info cm32181_info = {
> .attrs = &cm32181_attribute_group,
> };
>
> +#if defined(CONFIG_ACPI)
> +/* Parse acpi resources for a second i2c address on same adapter
could be a single line comment :)
the function does more than parse; I suggest to use strut i2c_client * as
the type for the second argument
please describe that the i2c address is put into data
the return type could be bool, 1 vs -1 is unusual and not clear, -1 on
success?
> + */
> +static int cm3218_get_i2c_address(struct acpi_resource *ares, void *data)
> +{
> + struct i2c_client *client = data;
> + struct acpi_resource_i2c_serialbus *sb;
> + acpi_status status;
> + acpi_handle adapter_handle;
> +
> + if (ares->type != ACPI_RESOURCE_TYPE_SERIAL_BUS)
> + return 1;
> +
> + sb = &ares->data.i2c_serial_bus;
> + if (sb->type != ACPI_RESOURCE_SERIAL_TYPE_I2C)
> + return 1;
> +
> + status = acpi_get_handle(ACPI_HANDLE(&client->dev),
> + sb->resource_source.string_ptr,
> + &adapter_handle);
> + if (!ACPI_SUCCESS(status))
> + return 1;
> +
> + if (adapter_handle != ACPI_HANDLE(&client->adapter->dev))
> + return 1;
> +
> + if (sb->slave_address == CM3218_ARA_ADDR)
> + return 1;
> +
> + client->addr = sb->slave_address;
> + client->flags &= ~I2C_CLIENT_TEN;
> + if (sb->access_mode == ACPI_I2C_10BIT_MODE)
> + client->flags |= I2C_CLIENT_TEN;
> +
> + return -1;
> +}
> +
> +/* Walk through acpi resources to find second i2c connection
single line comment?
> + */
> +static int cm3218_acpi_get_address(struct i2c_client *client)
> +{
> + int ret;
> + struct acpi_device *adev;
> + LIST_HEAD(ares);
> +
> + adev = ACPI_COMPANION(&client->dev);
> + if (!adev)
> + return -ENODEV;
> +
> + ret = acpi_dev_get_resources(adev,
> + &ares,
> + cm3218_get_i2c_address,
> + client);
> + acpi_dev_free_resource_list(&ares);
> + if (ret < 0)
> + return -ENODEV;
> +
> + return 0;
> +}
> +#else
> +static inline int cm3218_acpi_get_address(struct i2c_client *client)
why inline?
> +{
> + return -ENODEV;
> +}
> +#endif
> +
> static int cm32181_probe(struct i2c_client *client,
> const struct i2c_device_id *id)
> {
> struct cm32181_chip *cm32181;
> struct iio_dev *indio_dev;
> int ret;
> + struct i2c_smbus_alert_setup ara_setup;
> + const struct of_device_id *of_id;
> + const struct acpi_device_id *acpi_id;
>
> indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*cm32181));
> if (!indio_dev) {
> @@ -323,11 +402,65 @@ static int cm32181_probe(struct i2c_client *client,
> indio_dev->name = id->name;
> indio_dev->modes = INDIO_DIRECT_MODE;
>
> + /* Lookup for chip ID from platform, acpi or of device table */
> + if (id) {
> + cm32181->chip_id = id->driver_data;
> + } else if (ACPI_COMPANION(&client->dev)) {
> + acpi_id = acpi_match_device(client->dev.driver->acpi_match_table,
> + &client->dev);
> + if (!acpi_id)
> + return -ENODEV;
> +
> + cm32181->chip_id = (kernel_ulong_t)acpi_id->driver_data;
> + } else if (client->dev.of_node) {
> + of_id = of_match_device(clients->dev.driver->of_match_table,
> + &client->dev);
> + if (!of_id)
> + return -ENODEV;
> +
> + cm32181->chip_id = (kernel_ulong_t)of_id->data;
> + } else {
> + return -ENODEV;
> + }
> +
> + if (cm32181->chip_id == CM3218_ID) {
> + if (client->addr == CM3218_ARA_ADDR) {
> + /* In case first address is the ARA device
> + * lookup for a second one in acpi resources if
> + * this client is enumerated on acpi
> + */
> + ret = cm3218_acpi_get_address(client);
> + if (ret < 0)
> + return -ENODEV;
> + }
> +
> +#ifdef CONFIG_I2C_SMBUS
> + if (client->irq > 0) {
> + /* setup smb alert device
single line comment
> + */
> + ara_setup.irq = client->irq;
> + ara_setup.alert_edge_triggered = 0;
> + cm32181->ara = i2c_setup_smbus_alert(client->adapter,
> + &ara_setup);
> + if (!cm32181->ara)
> + return -ENODEV;
> + } else {
> + return -ENODEV;
> + }
> +#else
> + return -ENODEV;
> +#endif
> + }
> +
> ret = cm32181_reg_init(cm32181);
> if (ret) {
> dev_err(&client->dev,
> "%s: register init failed\n",
> __func__);
> +
> + if (cm32181->ara)
> + i2c_unregister_device(cm32181->ara);
> +
> return ret;
> }
>
> @@ -336,32 +469,58 @@ static int cm32181_probe(struct i2c_client *client,
> dev_err(&client->dev,
> "%s: regist device failed\n",
> __func__);
> +
> + if (cm32181->ara)
> + i2c_unregister_device(cm32181->ara);
> +
> return ret;
> }
>
> return 0;
> }
>
> +static int cm32181_remove(struct i2c_client *client)
> +{
> + struct iio_dev *indio_dev = i2c_get_clientdata(client);
> + struct cm32181_chip *cm32181 = iio_priv(indio_dev);
> +
> + if (cm32181->ara)
> + i2c_unregister_device(cm32181->ara);
> +
> + return 0;
> +};
> +
> static const struct i2c_device_id cm32181_id[] = {
> - { "cm32181", 0 },
> + { "cm32181", CM32181_ID },
> + { "cm3218", CM3218_ID },
> { }
> };
>
> MODULE_DEVICE_TABLE(i2c, cm32181_id);
>
> static const struct of_device_id cm32181_of_match[] = {
> - { .compatible = "capella,cm32181" },
> + { .compatible = "capella,cm32181", (void *)CM32181_ID },
> + { .compatible = "capella,cm3218", (void *)CM3218_ID },
> { }
> };
> MODULE_DEVICE_TABLE(of, cm32181_of_match);
>
> +static const struct acpi_device_id cm32181_acpi_match[] = {
> + { "CPLM3218", CM3218_ID },
> + { }
> +};
> +
> +MODULE_DEVICE_TABLE(acpi, cm32181_acpi_match);
> +
> static struct i2c_driver cm32181_driver = {
> .driver = {
> .name = "cm32181",
> .of_match_table = of_match_ptr(cm32181_of_match),
> + .acpi_match_table = ACPI_PTR(cm32181_acpi_match),
> },
> .id_table = cm32181_id,
> .probe = cm32181_probe,
> + .remove = cm32181_remove,
> };
>
> module_i2c_driver(cm32181_driver);
>
--
Peter Meerwald-Stadler
Mobile: +43 664 24 44 418
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