<div dir="ltr"><br><div class="gmail_extra"><br><br><div class="gmail_quote">On 15 July 2013 20:43, Rob Herring <span dir="ltr"><<a href="mailto:robherring2@gmail.com" target="_blank">robherring2@gmail.com</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">On 07/15/2013 10:36 AM, <a href="mailto:mathieu.poirier@linaro.org">mathieu.poirier@linaro.org</a> wrote:<br>
> From: "Mathieu J. Poirier" <<a href="mailto:mathieu.poirier@linaro.org">mathieu.poirier@linaro.org</a>><br>
><br>
> Adding a simple device tree binding for the specification of key sequences.<br>
> Definition of the keys found in the sequence are located in<br>
> 'include/uapi/linux/input.h'.<br>
><br>
> For the sysrq driver, holding the sequence of keys down for a specific amount of time<br>
> will reset the system.<br>
><br>
> Signed-off-by: Mathieu Poirier <<a href="mailto:mathieu.poirier@linaro.org">mathieu.poirier@linaro.org</a>><br>
> ---<br>
> changes for v4:<br>
> - Moved seach of reset sequence nodes to a single call.<br>
> ---<br>
> .../devicetree/bindings/input/input-reset.txt | 34 ++++++++++++++<br>
> drivers/tty/sysrq.c | 54 ++++++++++++++++++++++<br>
> 2 files changed, 88 insertions(+)<br>
> create mode 100644 Documentation/devicetree/bindings/input/input-reset.txt<br>
><br>
> diff --git a/Documentation/devicetree/bindings/input/input-reset.txt b/Documentation/devicetree/bindings/input/input-reset.txt<br>
> new file mode 100644<br>
> index 0000000..79504af<br>
> --- /dev/null<br>
> +++ b/Documentation/devicetree/bindings/input/input-reset.txt<br>
> @@ -0,0 +1,34 @@<br>
> +Input: sysrq reset sequence<br>
> +<br>
> +A simple binding to represent a set of keys as described in<br>
> +include/uapi/linux/input.h. This is to communicate a<br>
> +sequence of keys to the sysrq driver. Upon holding the keys<br>
> +for a specified amount of time (if specified) the system is<br>
> +sync'ed and reset.<br>
> +<br>
> +Key sequences are global to the system but all the keys in a<br>
> +set must be coming from the same input device.<br>
> +<br>
> +The /chosen node should contain a 'linux,sysrq-reset-seq' child<br>
> +node to define a set of keys.<br>
> +<br>
> +Required property:<br>
> +sysrq-reset-seq: array of keycodes<br>
> +<br>
> +Optional property:<br>
> +timeout-ms: duration keys must be pressed together in microseconds<br>
<br>
milliseconds (ms) or microseconds (us)?<br>
<br></blockquote><div><br></div><div>Right, milliseconds.</div><div> </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
> +before generating a sysrq<br>
> +<br>
> +Example:<br>
> +<br>
> + chosen {<br>
> + linux,sysrq-reset-seq {<br>
> + keyset = <0x03<br>
> + 0x04<br>
> + 0x0a>;<br>
> + timeout-ms = <3000>;<br>
> + };<br>
> + };<br>
> +<br>
> +Would represent KEY_2, KEY_3 and KEY_9.<br>
> +<br>
> diff --git a/drivers/tty/sysrq.c b/drivers/tty/sysrq.c<br>
> index b51c154..01a8729 100644<br>
> --- a/drivers/tty/sysrq.c<br>
> +++ b/drivers/tty/sysrq.c<br>
> @@ -44,6 +44,7 @@<br>
> #include <linux/uaccess.h><br>
> #include <linux/moduleparam.h><br>
> #include <linux/jiffies.h><br>
> +#include <linux/of.h><br>
><br>
> #include <asm/ptrace.h><br>
> #include <asm/irq_regs.h><br>
> @@ -671,6 +672,50 @@ static void sysrq_detect_reset_sequence(struct sysrq_state *state,<br>
> }<br>
> }<br>
><br>
> +static void sysrq_of_get_keyreset_config(void)<br>
> +{<br>
> + unsigned short key;<br>
> + struct device_node *np;<br>
> + const struct property *prop;<br>
> + const __be32 *val;<br>
> + int count, i;<br>
> +<br>
> + np = of_find_node_by_path("/chosen/linux,sysrq-reset-seq");<br>
> + if (!np) {<br>
> + pr_debug("No sysrq node found");<br>
> + goto out;<br>
> + }<br>
> +<br>
> + prop = of_find_property(np, "keyset", NULL);<br>
> + if (!prop || !prop->value) {<br>
> + pr_err("Invalid input keyset");<br>
> + goto out;<br>
> + }<br>
> +<br>
> + count = prop->length / sizeof(u32);<br>
> + val = prop->value;<br>
<br>
None of the existing helpers to retrieve property arrays doesn't work here?<br></blockquote><div><br></div><div>The problem here is that we never know how long the sequence will be. As such the 'of_property_read_uXY_array' functions won't work. Or maybe you're referring to another set of helpers... If so, please clarify.</div>
<div> </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<br>
> +<br>
> + if (count > SYSRQ_KEY_RESET_MAX)<br>
> + count = SYSRQ_KEY_RESET_MAX;<br>
> +<br>
> + /* reset in case a __weak definition was present */<br>
> + sysrq_reset_seq_len = 0;<br>
> +<br>
> + for (i = 0; i < count; i++) {<br>
> + key = (unsigned short)be32_to_cpup(val++);<br>
> + if (key == KEY_RESERVED || key > KEY_MAX)<br>
> + break;<br>
> +<br>
> + sysrq_reset_seq[sysrq_reset_seq_len++] = key;<br>
> + }<br>
> +<br>
> + /* get reset timeout if any */<br>
> + of_property_read_u32(np, "timeout-ms", &sysrq_reset_downtime_ms);<br>
> +<br>
> + out:<br>
> + ;<br>
> +}<br>
> +<br>
> static void sysrq_reinject_alt_sysrq(struct work_struct *work)<br>
> {<br>
> struct sysrq_state *sysrq =<br>
> @@ -688,6 +733,7 @@ static void sysrq_reinject_alt_sysrq(struct work_struct *work)<br>
> input_inject_event(handle, EV_KEY, KEY_SYSRQ, 1);<br>
> input_inject_event(handle, EV_SYN, SYN_REPORT, 1);<br>
><br>
> +<br>
<br>
spurious ws change </blockquote><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<br>
> input_inject_event(handle, EV_KEY, KEY_SYSRQ, 0);<br>
> input_inject_event(handle, EV_KEY, alt_code, 0);<br>
> input_inject_event(handle, EV_SYN, SYN_REPORT, 1);<br>
> @@ -903,6 +949,7 @@ static inline void sysrq_register_handler(void)<br>
> int error;<br>
> int i;<br>
><br>
> + /* first check if a __weak interface was instantiated */<br>
> for (i = 0; i < ARRAY_SIZE(sysrq_reset_seq); i++) {<br>
> key = platform_sysrq_reset_seq[i];<br>
> if (key == KEY_RESERVED || key > KEY_MAX)<br>
> @@ -911,6 +958,13 @@ static inline void sysrq_register_handler(void)<br>
> sysrq_reset_seq[sysrq_reset_seq_len++] = key;<br>
> }<br>
><br>
> + /*<br>
> + * DT configuration takes precedence over anything<br>
> + * that would have been defined via the __weak<br>
> + * interface<br>
> + */<br>
> + sysrq_of_get_keyreset_config();<br>
> +<br>
> error = input_register_handler(&sysrq_handler);<br>
> if (error)<br>
> pr_err("Failed to register input handler, error %d", error);<br>
><br>
<br>
</blockquote></div><br></div></div>