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>
---
changes for v3:
- Simplified binding definition.
- Renamed binding and moved to chosen.
---
.../devicetree/bindings/input/input-reset.txt | 34 +++++++++++++
drivers/tty/sysrq.c | 58 ++++++++++++++++++++++
2 files changed, 92 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..79504af
--- /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 keycodes
+
+Optional property:
+timeout-ms: duration keys must be pressed together in microseconds
+before generating a sysrq
+
+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 b51c154..4b77adf 100644
--- a/drivers/tty/sysrq.c
+++ b/drivers/tty/sysrq.c
@@ -44,6 +44,7 @@
#include <linux/uaccess.h>
#include <linux/moduleparam.h>
#include <linux/jiffies.h>
+#include <linux/of.h>
#include <asm/ptrace.h>
#include <asm/irq_regs.h>
@@ -671,6 +672,54 @@ static void sysrq_detect_reset_sequence(struct sysrq_state *state,
}
}
+static void sysrq_of_get_keyreset_config(void)
+{
+ unsigned short key;
+ struct device_node *np;
+ const struct property *prop;
+ const __be32 *val;
+ int count, i;
+
+ np = of_find_node_by_path("/chosen");
+ if (!np)
+ goto out;
+
+ np = of_find_node_by_name(np, "linux,sysrq-reset-seq");
+ if (!np) {
+ pr_debug("No sysrq node found");
+ goto out;
+ }
+
+ prop = of_find_property(np, "keyset", NULL);
+ if (!prop || !prop->value) {
+ pr_err("Invalid input keyset");
+ goto out;
+ }
+
+ count = prop->length / sizeof(u32);
+ val = prop->value;
+
+ if (count > SYSRQ_KEY_RESET_MAX)
+ count = SYSRQ_KEY_RESET_MAX;
+
+ /* reset in case a __weak definition was present */
+ sysrq_reset_seq_len = 0;
+
+ for (i = 0; i < count; i++) {
+ key = (unsigned short)be32_to_cpup(val++);
+ if (key == KEY_RESERVED || key > KEY_MAX)
+ break;
+
+ sysrq_reset_seq[sysrq_reset_seq_len++] = key;
+ }
+
+ /* get reset timeout if any */
+ of_property_read_u32(np, "timeout-ms", &sysrq_reset_downtime_ms);
+
+ out:
+ ;
+}
+
static void sysrq_reinject_alt_sysrq(struct work_struct *work)
{
struct sysrq_state *sysrq =
@@ -688,6 +737,7 @@ static void sysrq_reinject_alt_sysrq(struct work_struct *work)
input_inject_event(handle, EV_KEY, KEY_SYSRQ, 1);
input_inject_event(handle, EV_SYN, SYN_REPORT, 1);
+
input_inject_event(handle, EV_KEY, KEY_SYSRQ, 0);
input_inject_event(handle, EV_KEY, alt_code, 0);
input_inject_event(handle, EV_SYN, SYN_REPORT, 1);
@@ -903,6 +953,7 @@ 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)
@@ -911,6 +962,13 @@ 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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