Re: [PATCH 6/7] iio: mlx90614: Add power management
On 09/03/15 16:43, Wolfram Sang wrote: > On Mon, Mar 09, 2015 at 03:39:35PM +, Jonathan Cameron wrote: >> On 25/02/15 15:55, Vianney le Clément de Saint-Marcq wrote: >>> Add support for system sleep and runtime power management. >>> >>> To wake up the device, the SDA line should be held low for at least 33ms >>> while SCL is high. As this is not possible using the i2c API (and not >>> supported by all i2c adapters), a GPIO connected to the SDA line is >>> needed. The GPIO is named "wakeup" and can be specified in a device >>> tree with the "wakeup-gpios" binding. >> Needs some i2c specialist input on this! As you mentioned it is liable >> to be controversial. Wolfram, is this a one off special or do >> any other devices do this sort of magic? > > s/magic/insanity/ :) > > I have never heard of something like this. Unsuprisingly, I can > not recommend doing it this way. But we all know hardware... > > And while we could think about reusing the bus_recovery_infrastructure, > I don't think it is worth the hazzle. So, doing this GPIO fallback may > well be the best we can do now. > Fair enough. Lets go with this approach then and hope this is the only bit of hardware ever to do this (yeah right ;) -- To unsubscribe from this list: send the line "unsubscribe linux-i2c" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [PATCH 6/7] iio: mlx90614: Add power management
On Mon, Mar 09, 2015 at 03:39:35PM +, Jonathan Cameron wrote: > On 25/02/15 15:55, Vianney le Clément de Saint-Marcq wrote: > > Add support for system sleep and runtime power management. > > > > To wake up the device, the SDA line should be held low for at least 33ms > > while SCL is high. As this is not possible using the i2c API (and not > > supported by all i2c adapters), a GPIO connected to the SDA line is > > needed. The GPIO is named "wakeup" and can be specified in a device > > tree with the "wakeup-gpios" binding. > Needs some i2c specialist input on this! As you mentioned it is liable > to be controversial. Wolfram, is this a one off special or do > any other devices do this sort of magic? s/magic/insanity/ :) I have never heard of something like this. Unsuprisingly, I can not recommend doing it this way. But we all know hardware... And while we could think about reusing the bus_recovery_infrastructure, I don't think it is worth the hazzle. So, doing this GPIO fallback may well be the best we can do now. signature.asc Description: Digital signature
Re: [PATCH 6/7] iio: mlx90614: Add power management
On 09/03/15 15:39, Jonathan Cameron wrote:
> On 25/02/15 15:55, Vianney le Clément de Saint-Marcq wrote:
>> Add support for system sleep and runtime power management.
>>
>> To wake up the device, the SDA line should be held low for at least 33ms
>> while SCL is high. As this is not possible using the i2c API (and not
>> supported by all i2c adapters), a GPIO connected to the SDA line is
>> needed. The GPIO is named "wakeup" and can be specified in a device
>> tree with the "wakeup-gpios" binding.
> Needs some i2c specialist input on this! As you mentioned it is liable
> to be controversial. Wolfram, is this a one off special or do
> any other devices do this sort of magic?
>>
>> If the wake-up GPIO is not given, disable power management for the
>> device. Entering sleep requires an SMBus byte access, hence power
>> management is also disabled if byte access is not supported by the
>> adapter.
>>
>> Signed-off-by: Vianney le Clément de Saint-Marcq
>>
>> Cc: Arnout Vandecappelle (Essensium/Mind)
Again, with a current address for Wolfram.
>>
>> ---
>>
>> The default autosleep delay (5s) is chosen arbitrarily, trying to take
>> into account the long startup time (250ms). Feel free to change it to
>> another value if you think it is saner.
>> ---
>> .../bindings/iio/temperature/mlx90614.txt | 24 ++
>> .../devicetree/bindings/vendor-prefixes.txt| 1 +
>> drivers/iio/temperature/mlx90614.c | 244
>> -
>> 3 files changed, 267 insertions(+), 2 deletions(-)
>> create mode 100644
>> Documentation/devicetree/bindings/iio/temperature/mlx90614.txt
>>
>> diff --git a/Documentation/devicetree/bindings/iio/temperature/mlx90614.txt
>> b/Documentation/devicetree/bindings/iio/temperature/mlx90614.txt
>> new file mode 100644
>> index 000..9be57b0
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/iio/temperature/mlx90614.txt
>> @@ -0,0 +1,24 @@
>> +* Melexis MLX90614 contactless IR temperature sensor
>> +
>> +http://melexis.com/Infrared-Thermometer-Sensors/Infrared-Thermometer-Sensors/MLX90614-615.aspx
>> +
>> +Required properties:
>> +
>> + - compatible: should be "melexis,mlx90614"
>> + - reg: the I2C address of the sensor
>> +
>> +Optional properties:
>> +
>> + - wakeup-gpios: device tree identifier of the GPIO connected to the SDA
>> line
>> + to hold low in order to wake up the device. In normal operation, the
>> + GPIO is set as input and will not interfere in I2C communication.
>> There
>> + is no need for a GPIO driving the SCL line. If no GPIO is given,
>> power
>> + management is disabled.
>> +
>> +Example:
>> +
>> +mlx90614@5a {
>> +compatible = "melexis,mlx90614";
>> +reg = <0x5a>;
>> +wakeup-gpios = <&gpio0 2 GPIO_ACTIVE_HIGH>;
>> +};
>> diff --git a/Documentation/devicetree/bindings/vendor-prefixes.txt
>> b/Documentation/devicetree/bindings/vendor-prefixes.txt
>> index 389ca13..ceacc40 100644
>> --- a/Documentation/devicetree/bindings/vendor-prefixes.txt
>> +++ b/Documentation/devicetree/bindings/vendor-prefixes.txt
>> @@ -108,6 +108,7 @@ lltc Linear Technology Corporation
>> marvell Marvell Technology Group Ltd.
>> maxim Maxim Integrated Products
>> mediatekMediaTek Inc.
>> +melexis Melexis N.V.
>> merrii Merrii Technology Co., Ltd.
>> micrel Micrel Inc.
>> microchip Microchip Technology Inc.
>> diff --git a/drivers/iio/temperature/mlx90614.c
>> b/drivers/iio/temperature/mlx90614.c
>> index ab98fb6..49c517a 100644
>> --- a/drivers/iio/temperature/mlx90614.c
>> +++ b/drivers/iio/temperature/mlx90614.c
>> @@ -12,13 +12,22 @@
>> *
>> * (7-bit I2C slave address 0x5a, 100KHz bus speed only!)
>> *
>> - * TODO: sleep mode
>> + * To wake up from sleep mode, the SDA line must be held low while SCL is
>> high
>> + * for at least 33ms. This is achieved with an extra GPIO that can be
>> connected
>> + * directly to the SDA line. In normal operation, the GPIO is set as input
>> and
>> + * will not interfere in I2C communication. While the GPIO is driven low,
>> the
>> + * i2c adapter is locked since it cannot be used by other clients. The SCL
>> line
>> + * always has a pull-up so we do not need an extra GPIO to drive it high.
>> If
>> + * the "wakeup" GPIO is not given, power management will be disabled.
>> */
>>
>> #include
>> #include
>> #include
>> #include
>> +#include
>> +#include
>> +#include
>>
>> #include
>> #include
>> @@ -53,9 +62,13 @@
>> #define MLX90614_TIMING_WAKEUP 34 /* time to hold SDA low for wake-up */
>> #define MLX90614_TIMING_STARTUP 250 /* time before first data after wake-up
>> */
>>
>> +#define MLX90614_AUTOSLEEP_DELAY 5000 /* default autosleep delay */
>> +
>> struct mlx90614_data {
>> struct i2c_client *client;
>> struct mutex lock; /* for EEPROM access only */
>> +struct gpio_desc *wakeup_gpio; /* NULL to disable sleep/wake-up */
>> +unsigned long ready_timestamp; /* in j
Re: [PATCH 6/7] iio: mlx90614: Add power management
On 25/02/15 15:55, Vianney le Clément de Saint-Marcq wrote:
> Add support for system sleep and runtime power management.
>
> To wake up the device, the SDA line should be held low for at least 33ms
> while SCL is high. As this is not possible using the i2c API (and not
> supported by all i2c adapters), a GPIO connected to the SDA line is
> needed. The GPIO is named "wakeup" and can be specified in a device
> tree with the "wakeup-gpios" binding.
Needs some i2c specialist input on this! As you mentioned it is liable
to be controversial. Wolfram, is this a one off special or do
any other devices do this sort of magic?
>
> If the wake-up GPIO is not given, disable power management for the
> device. Entering sleep requires an SMBus byte access, hence power
> management is also disabled if byte access is not supported by the
> adapter.
>
> Signed-off-by: Vianney le Clément de Saint-Marcq
>
> Cc: Arnout Vandecappelle (Essensium/Mind)
>
> ---
>
> The default autosleep delay (5s) is chosen arbitrarily, trying to take
> into account the long startup time (250ms). Feel free to change it to
> another value if you think it is saner.
> ---
> .../bindings/iio/temperature/mlx90614.txt | 24 ++
> .../devicetree/bindings/vendor-prefixes.txt| 1 +
> drivers/iio/temperature/mlx90614.c | 244
> -
> 3 files changed, 267 insertions(+), 2 deletions(-)
> create mode 100644
> Documentation/devicetree/bindings/iio/temperature/mlx90614.txt
>
> diff --git a/Documentation/devicetree/bindings/iio/temperature/mlx90614.txt
> b/Documentation/devicetree/bindings/iio/temperature/mlx90614.txt
> new file mode 100644
> index 000..9be57b0
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/iio/temperature/mlx90614.txt
> @@ -0,0 +1,24 @@
> +* Melexis MLX90614 contactless IR temperature sensor
> +
> +http://melexis.com/Infrared-Thermometer-Sensors/Infrared-Thermometer-Sensors/MLX90614-615.aspx
> +
> +Required properties:
> +
> + - compatible: should be "melexis,mlx90614"
> + - reg: the I2C address of the sensor
> +
> +Optional properties:
> +
> + - wakeup-gpios: device tree identifier of the GPIO connected to the SDA
> line
> + to hold low in order to wake up the device. In normal operation, the
> + GPIO is set as input and will not interfere in I2C communication.
> There
> + is no need for a GPIO driving the SCL line. If no GPIO is given, power
> + management is disabled.
> +
> +Example:
> +
> +mlx90614@5a {
> + compatible = "melexis,mlx90614";
> + reg = <0x5a>;
> + wakeup-gpios = <&gpio0 2 GPIO_ACTIVE_HIGH>;
> +};
> diff --git a/Documentation/devicetree/bindings/vendor-prefixes.txt
> b/Documentation/devicetree/bindings/vendor-prefixes.txt
> index 389ca13..ceacc40 100644
> --- a/Documentation/devicetree/bindings/vendor-prefixes.txt
> +++ b/Documentation/devicetree/bindings/vendor-prefixes.txt
> @@ -108,6 +108,7 @@ lltc Linear Technology Corporation
> marvell Marvell Technology Group Ltd.
> maximMaxim Integrated Products
> mediatek MediaTek Inc.
> +melexis Melexis N.V.
> merrii Merrii Technology Co., Ltd.
> micrel Micrel Inc.
> microchipMicrochip Technology Inc.
> diff --git a/drivers/iio/temperature/mlx90614.c
> b/drivers/iio/temperature/mlx90614.c
> index ab98fb6..49c517a 100644
> --- a/drivers/iio/temperature/mlx90614.c
> +++ b/drivers/iio/temperature/mlx90614.c
> @@ -12,13 +12,22 @@
> *
> * (7-bit I2C slave address 0x5a, 100KHz bus speed only!)
> *
> - * TODO: sleep mode
> + * To wake up from sleep mode, the SDA line must be held low while SCL is
> high
> + * for at least 33ms. This is achieved with an extra GPIO that can be
> connected
> + * directly to the SDA line. In normal operation, the GPIO is set as input
> and
> + * will not interfere in I2C communication. While the GPIO is driven low,
> the
> + * i2c adapter is locked since it cannot be used by other clients. The SCL
> line
> + * always has a pull-up so we do not need an extra GPIO to drive it high. If
> + * the "wakeup" GPIO is not given, power management will be disabled.
> */
>
> #include
> #include
> #include
> #include
> +#include
> +#include
> +#include
>
> #include
> #include
> @@ -53,9 +62,13 @@
> #define MLX90614_TIMING_WAKEUP 34 /* time to hold SDA low for wake-up */
> #define MLX90614_TIMING_STARTUP 250 /* time before first data after wake-up
> */
>
> +#define MLX90614_AUTOSLEEP_DELAY 5000 /* default autosleep delay */
> +
> struct mlx90614_data {
> struct i2c_client *client;
> struct mutex lock; /* for EEPROM access only */
> + struct gpio_desc *wakeup_gpio; /* NULL to disable sleep/wake-up */
> + unsigned long ready_timestamp; /* in jiffies */
> };
>
> /*
> @@ -96,6 +109,52 @@ static s32 mlx90614_write_word(const struct i2c_client
> *client, u8 command,
> return ret;
> }
>
> +#ifdef CONFIG_PM
> +/*
> + * If @startup is t
