On Fri, 2018-06-08 at 23:11 +0200, Hans de Goede wrote:
> Normally i2c_new_device will check that a client at the same address
> does
> not already exists.
>
> On systems with ACPI instantiated i2c-clients, normally there is 1
> fw_node
> per i2c-device and that fw-node contains 1 I2cSerialBus resource for
> that 1
> i2c-device.
>
> But in some rare cases the manufacturer has decided to describe
> multiple
> i2c-devices in a single ACPI fwnode with multiple I2cSerialBus
> resources.
>
> After an earlier attempt to fix this in the i2c-core which resulted in
> a
> lot of extra code to support this corner-case it was decided to go for
> a
> different approach. The next patch in this series introduces a new
> special
> i2c-multi-instantiate driver which can be build as a module and which
> will
> bind to the i2c-client which gets instantiated by the core for the
> first
> I2cSerialBus resource in the fwnode.
>
> This driver will instantiate a new i2c-client per I2cSerialBus
> resource,
> using the driver_data from the acpi_device_id it is binding to to tell
> it
> which chip-type (and optional irq-resource) to use when instantiating.
>
> Since it binds to the core instantiated i2c-client and claims the
> acpi_device_id of the fwnode, it also needs to instantiate a new i2c-
> client
> for the first I2cSerialBus resource uses the chip-id for the real
> driver,
> so that that can bind to the i2c-device described by the first
> I2cSerialBus
> resource, this requires the new I2C_CLIENT_IGNORE_BUSY flag.
>
> Note this means that we will be instantiating 2 i2c_client-s for the
> first
> I2cSerialBus resource, this is not pretty, but since the multi-
> instantiate
> driver does exactly 0 i2c-transfers this is not a problem.
>
You forgot to Cc Heikki.
> Signed-off-by: Hans de Goede <hdegoede@xxxxxxxxxx>
> ---
> drivers/i2c/i2c-core-base.c | 11 +++++++----
> include/linux/i2c.h | 3 +++
> 2 files changed, 10 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/i2c/i2c-core-base.c b/drivers/i2c/i2c-core-base.c
> index a17f46a95f73..77d70b611bc5 100644
> --- a/drivers/i2c/i2c-core-base.c
> +++ b/drivers/i2c/i2c-core-base.c
> @@ -721,7 +721,7 @@ i2c_new_device(struct i2c_adapter *adap, struct
> i2c_board_info const *info)
> if (info->archdata)
> client->dev.archdata = *info->archdata;
>
> - client->flags = info->flags;
> + client->flags = info->flags & ~I2C_CLIENT_IGNORE_BUSY;
> client->addr = info->addr;
>
> client->irq = info->irq;
> @@ -739,9 +739,12 @@ i2c_new_device(struct i2c_adapter *adap, struct
> i2c_board_info const *info)
> }
>
> /* Check for address business */
> - status = i2c_check_addr_busy(adap,
> i2c_encode_flags_to_addr(client));
> - if (status)
> - goto out_err;
> + if (!(info->flags & I2C_CLIENT_IGNORE_BUSY)) {
> + status = i2c_check_addr_busy(adap,
> + i2c_encode_flags_to_addr
> (client));
> + if (status)
> + goto out_err;
> + }
>
> client->dev.parent = &client->adapter->dev;
> client->dev.bus = &i2c_bus_type;
> diff --git a/include/linux/i2c.h b/include/linux/i2c.h
> index 44ad14e016b5..3ad73cf1b187 100644
> --- a/include/linux/i2c.h
> +++ b/include/linux/i2c.h
> @@ -775,6 +775,9 @@ i2c_unlock_adapter(struct i2c_adapter *adapter)
> #define I2C_CLIENT_SLAVE 0x20 /* we are the slave */
> #define I2C_CLIENT_HOST_NOTIFY 0x40 /* We want to use
> I2C host notify */
> #define I2C_CLIENT_WAKE 0x80 /* for board_info;
> true iff can wake */
> +#define I2C_CLIENT_IGNORE_BUSY 0x100 /* For board_info;
> skip busy check */
> + /* Do NOT use, reserved for
> use by */
> + /* drv/i2c/i2c-multi-
> instantiate.c */
> #define I2C_CLIENT_SCCB 0x9000 /* Use
> Omnivision SCCB protocol */
> /* Must match
> I2C_M_STOP|IGNORE_NAK */
>
--
Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
Intel Finland Oy
