On Wed, Sep 24, 2014 at 02:11:17PM +0100, Frans Klaver wrote:
> In some cases you want to instantiate a battery even before it is
> attached; it is perfectly reasonable for a device to start up on
> wall-power and be connected to a battery later. The current advice is to
> instantiate a device explicitly in the kernel, or probe for the device
> from userspace. The downside of these approaches is that the user needs
> to keep the information related to the i2c battery in different places,
> which is inconvenient.
This really sounds like a Linux policy issue rather than something that
should be described in dt.
Presumably there's a reason we sanity cehck this in the first place.
What happens while the battery isn't plugged in? What can fail, and how?
Mark.
> Add the "sbs,always-present" option to the device tree. If set, the
> battery is instantiated without sanity checking the connection.
>From the description above, this name is incorrect. You're adding this
property to work around the battery _not_ being present at probe-time.
>From a binding point of view, "instantiated" is somewhat meaningless --
that's an OS level detail rather than a contract detail.
Mark.
>
> Signed-off-by: Frans Klaver <frans.klaver@xxxxxxxxx>
> ---
> drivers/power/sbs-battery.c | 11 +++++++++--
> include/linux/power/sbs-battery.h | 3 +++
> 2 files changed, 12 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/power/sbs-battery.c b/drivers/power/sbs-battery.c
> index b5f2a76..5d327b5 100644
> --- a/drivers/power/sbs-battery.c
> +++ b/drivers/power/sbs-battery.c
> @@ -651,6 +651,9 @@ static struct sbs_platform_data *sbs_of_populate_pdata(
> if (!rc)
> pdata->poll_retry_count = prop;
>
> + pdata->always_present = of_property_read_bool(of_node,
> + "sbs,always-present");
> +
> if (!of_get_property(of_node, "sbs,battery-detect-gpios", NULL)) {
> pdata->battery_detect = -1;
> goto of_out;
> @@ -761,10 +764,14 @@ static int sbs_probe(struct i2c_client *client,
>
> skip_gpio:
> /*
> - * Before we register, we need to make sure we can actually talk
> + * Before we register, we might need to make sure we can actually talk
> * to the battery.
> */
> - rc = sbs_read_word_data(client, sbs_data[REG_STATUS].addr);
> + if (!pdata->always_present)
> + rc = sbs_read_word_data(client, sbs_data[REG_STATUS].addr);
> + else
> + rc = 0;
> +
> if (rc < 0) {
> dev_err(&client->dev, "%s: Failed to get device status\n",
> __func__);
> diff --git a/include/linux/power/sbs-battery.h b/include/linux/power/sbs-battery.h
> index 2b0a9d9..724bd9b 100644
> --- a/include/linux/power/sbs-battery.h
> +++ b/include/linux/power/sbs-battery.h
> @@ -31,12 +31,15 @@
> * @i2c_retry_count: # of times to retry on i2c IO failure
> * @poll_retry_count: # of times to retry looking for new status after
> * external change notification
> + * @always_present: the device is instantiated even if the battery
> + * is not physically present
> */
> struct sbs_platform_data {
> int battery_detect;
> int battery_detect_present;
> int i2c_retry_count;
> int poll_retry_count;
> + bool always_present;
> };
>
> #endif
> --
> 2.1.0
>
>
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