> 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.capdevi...@no-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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