On Mon, Jul 29, 2013 at 10:33 AM, <mathieu.poirier@xxxxxxxxxx> wrote:
> From: "Mathieu J. Poirier" <mathieu.poirier@xxxxxxxxxx>
>
> Adding a simple device tree binding for the specification of key sequences.
> Definition of the keys found in the sequence are located in
> 'include/uapi/linux/input.h'.
>
> For the sysrq driver, holding the sequence of keys down for a specific amount of time
> will reset the system.
>
> Signed-off-by: Mathieu Poirier <mathieu.poirier@xxxxxxxxxx>
Acked-by: Grant Likely <grant.likely@xxxxxxxxxx>
g.
> ---
> changes for v6:
> - Made binding description more specific. 'sysrq-reset-seq's definition
> was enhanced and the case where 'timeout-ms' is omitted clearly
> explained.
> ---
> .../devicetree/bindings/input/input-reset.txt | 34 ++++++++++++++++++++
> drivers/tty/sysrq.c | 37 ++++++++++++++++++++++
> 2 files changed, 71 insertions(+)
> create mode 100644 Documentation/devicetree/bindings/input/input-reset.txt
>
> diff --git a/Documentation/devicetree/bindings/input/input-reset.txt b/Documentation/devicetree/bindings/input/input-reset.txt
> new file mode 100644
> index 0000000..13421a9
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/input/input-reset.txt
> @@ -0,0 +1,34 @@
> +Input: sysrq reset sequence
> +
> +A simple binding to represent a set of keys as described in
> +include/uapi/linux/input.h. This is to communicate a
> +sequence of keys to the sysrq driver. Upon holding the keys
> +for a specified amount of time (if specified) the system is
> +sync'ed and reset.
> +
> +Key sequences are global to the system but all the keys in a
> +set must be coming from the same input device.
> +
> +The /chosen node should contain a 'linux,sysrq-reset-seq' child
> +node to define a set of keys.
> +
> +Required property:
> +sysrq-reset-seq: array of Linux keycodes, one keycode per cell.
> +
> +Optional property:
> +timeout-ms: duration keys must be pressed together in milliseconds
> +before generating a sysrq. If omitted the system is rebooted
> +immediately when a valid sequence has beend recognized.
> +
> +Example:
> +
> + chosen {
> + linux,sysrq-reset-seq {
> + keyset = <0x03
> + 0x04
> + 0x0a>;
> + timeout-ms = <3000>;
> + };
> + };
> +
> +Would represent KEY_2, KEY_3 and KEY_9.
> diff --git a/drivers/tty/sysrq.c b/drivers/tty/sysrq.c
> index d5cc3ac..b04a24d 100644
> --- a/drivers/tty/sysrq.c
> +++ b/drivers/tty/sysrq.c
> @@ -45,6 +45,7 @@
> #include <linux/moduleparam.h>
> #include <linux/jiffies.h>
> #include <linux/syscalls.h>
> +#include <linux/of.h>
>
> #include <asm/ptrace.h>
> #include <asm/irq_regs.h>
> @@ -681,6 +682,34 @@ static void sysrq_detect_reset_sequence(struct sysrq_state *state,
> }
> }
>
> +static void sysrq_of_get_keyreset_config(void)
> +{
> + u32 key;
> + struct device_node *np;
> + struct property *prop;
> + const __be32 *p;
> +
> + np = of_find_node_by_path("/chosen/linux,sysrq-reset-seq");
> + if (!np) {
> + pr_debug("No sysrq node found");
> + return;
> + }
> +
> + /* reset in case a __weak definition was present */
> + sysrq_reset_seq_len = 0;
> +
> + of_property_for_each_u32(np, "keyset", prop, p, key) {
> + if ((key == KEY_RESERVED || key > KEY_MAX) ||
> + (sysrq_reset_seq_len == SYSRQ_KEY_RESET_MAX))
> + break;
> +
> + sysrq_reset_seq[sysrq_reset_seq_len++] = (unsigned short)key;
> + }
> +
> + /* get reset timeout if any */
> + of_property_read_u32(np, "timeout-ms", &sysrq_reset_downtime_ms);
> +}
> +
> static void sysrq_reinject_alt_sysrq(struct work_struct *work)
> {
> struct sysrq_state *sysrq =
> @@ -914,6 +943,7 @@ static inline void sysrq_register_handler(void)
> int error;
> int i;
>
> + /* first check if a __weak interface was instantiated */
> for (i = 0; i < ARRAY_SIZE(sysrq_reset_seq); i++) {
> key = platform_sysrq_reset_seq[i];
> if (key == KEY_RESERVED || key > KEY_MAX)
> @@ -922,6 +952,13 @@ static inline void sysrq_register_handler(void)
> sysrq_reset_seq[sysrq_reset_seq_len++] = key;
> }
>
> + /*
> + * DT configuration takes precedence over anything
> + * that would have been defined via the __weak
> + * interface
> + */
> + sysrq_of_get_keyreset_config();
> +
> error = input_register_handler(&sysrq_handler);
> if (error)
> pr_err("Failed to register input handler, error %d", error);
> --
> 1.8.1.2
>
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