Re: [PATCH v2 2/5] Input: atkbd: Expose function row physical map to userspace

Dmitry Torokhov
2020-03-26T21:27:11Z

On Tue, Mar 24, 2020 at 05:35:15AM -0700, Rajat Jain wrote:
> Certain keyboards have their top-row keys intended
> for actions such as "Browser back", "Browser Refresh", "Fullscreen"
> etc as their primary mode, thus they will send physical codes for those
> actions. Further, they don't have a dedicated "Fn" key so don't have
> the capability to generate function key codes (e.g. F1, F2 etc..).
> However in this case, if userspace still wants to "synthesize" those
> function keys using the top row action keys, it needs to know the
> physical position of the top row keys. (Essentially a mapping between
> usage codes and a physical location in the top row).
>
> This patch enhances the atkbd driver to receive such a mapping from the
> firmware / device tree, and expose it to userspace in the form of
> a function-row-physmap attribute. The attribute would be a space
> separated ordered list of physical codes, for the keys in the function
> row, in left-to-right order.
>
> The attribute will only be present if the kernel knows about such
> mapping, otherwise the attribute shall not be visible.
>
> Signed-off-by: Rajat Jain <rajatja@google.com>
> ---
> v2: Remove the Change-Id from the commit log
>
> drivers/input/keyboard/atkbd.c | 59 ++++++++++++++++++++++++++++++++++
> 1 file changed, 59 insertions(+)
>
> diff --git a/drivers/input/keyboard/atkbd.c b/drivers/input/keyboard/atkbd.c
> index 7e3eae54c1926..7623eebef2593 100644
> --- a/drivers/input/keyboard/atkbd.c
> +++ b/drivers/input/keyboard/atkbd.c
> @@ -24,6 +24,7 @@
> #include <linux/libps2.h>
> #include <linux/mutex.h>
> #include <linux/dmi.h>
> +#include <linux/property.h>
>
> #define DRIVER_DESC "AT and PS/2 keyboard driver"
>
> @@ -63,6 +64,8 @@ static bool atkbd_terminal;
> module_param_named(terminal, atkbd_terminal, bool, 0);
> MODULE_PARM_DESC(terminal, "Enable break codes on an IBM Terminal keyboard connected via AT/PS2");
>
> +#define MAX_FUNCTION_ROW_KEYS 24
> +
> /*
> * Scancode to keycode tables. These are just the default setting, and
> * are loadable via a userland utility.
> @@ -230,6 +233,9 @@ struct atkbd {
>
> /* Serializes reconnect(), attr->set() and event work */
> struct mutex mutex;
> +
> + u16 function_row_physmap[MAX_FUNCTION_ROW_KEYS];
> + int num_function_row_keys;
> };
>
> /*
> @@ -283,6 +289,7 @@ static struct device_attribute atkbd_attr_##_name = \
> __ATTR(_name, S_IRUGO, atkbd_do_show_##_name, NULL);
>
> ATKBD_DEFINE_RO_ATTR(err_count);
> +ATKBD_DEFINE_RO_ATTR(function_row_physmap);
>
> static struct attribute *atkbd_attributes[] = {
> &atkbd_attr_extra.attr,
> @@ -292,11 +299,42 @@ static struct attribute *atkbd_attributes[] = {
> &atkbd_attr_softrepeat.attr,
> &atkbd_attr_softraw.attr,
> &atkbd_attr_err_count.attr,
> + &atkbd_attr_function_row_physmap.attr,
> NULL
> };
>
> +static ssize_t atkbd_show_function_row_physmap(struct atkbd *atkbd, char *buf)
> +{
> + ssize_t size = 0;
> + int i;
> +
> + if (!atkbd->num_function_row_keys)
> + return 0;
> +
> + for (i = 0; i < atkbd->num_function_row_keys; i++)
> + size += sprintf(buf + size, "%02X ",
> + atkbd->function_row_physmap[i]);
> + size += sprintf(buf + size, "\n");
> + return size;
> +}
> +
> +static umode_t atkbd_attr_is_visible(struct kobject *kobj,
> + struct attribute *attr, int i)
> +{
> + struct device *dev = container_of(kobj, struct device, kobj);
> + struct serio *serio = to_serio_port(dev);
> + struct atkbd *atkbd = serio_get_drvdata(serio);
> +
> + if (attr == &atkbd_attr_function_row_physmap.attr &&
> + !atkbd->num_function_row_keys)
> + return 0;
> +
> + return attr->mode;
> +}
> +
> static struct attribute_group atkbd_attribute_group = {
> .attrs = atkbd_attributes,
> + .is_visible = atkbd_attr_is_visible,
> };
>
> static const unsigned int xl_table[] = {
> @@ -1121,6 +1159,25 @@ static void atkbd_set_device_attrs(struct atkbd *atkbd)
> }
> }
>
> +static void atkbd_parse_fwnode_data(struct serio *serio)
> +{
> + struct atkbd *atkbd = serio_get_drvdata(serio);
> + struct device *dev = &serio->dev;
> + int n;
> +
> + if (!dev_fwnode(dev))
> + return;

I do not think we need this guard.

> +
> + /* Parse "function-row-physmap" property */
> + n = device_property_count_u16(dev, "function-row-physmap");
> + if (n > 0 && n <= MAX_FUNCTION_ROW_KEYS &&
> + !device_property_read_u16_array(dev, "function-row-physmap",
> + atkbd->function_row_physmap, n)) {
> + atkbd->num_function_row_keys = n;
> + dev_info(dev, "FW reported %d function-row key locations\n", n);

dev_dbg().

> + }
> +}
> +
> /*
> * atkbd_connect() is called when the serio module finds an interface
> * that isn't handled yet by an appropriate device driver. We check if
> @@ -1184,6 +1241,8 @@ static int atkbd_connect(struct serio *serio, struct serio_driver *drv)
> atkbd->id = 0xab00;
> }
>
> + atkbd_parse_fwnode_data(serio);
> +
> atkbd_set_keycode_table(atkbd);
> atkbd_set_device_attrs(atkbd);
>
> --
> 2.25.1.696.g5e7596f4ac-goog
>

--
Dmitry