Input: sysrq - DT binding for key sequence
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@linaro.org> Acked-by: Grant Likely <grant.likely@linaro.org> Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
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Documentation/devicetree/bindings/input/input-reset.txt
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33
Documentation/devicetree/bindings/input/input-reset.txt
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Input: sysrq reset sequence
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A simple binding to represent a set of keys as described in
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include/uapi/linux/input.h. This is to communicate a sequence of keys to the
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sysrq driver. Upon holding the keys for a specified amount of time (if
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specified) the system is sync'ed and reset.
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Key sequences are global to the system but all the keys in a set must be coming
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from the same input device.
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The /chosen node should contain a 'linux,sysrq-reset-seq' child node to define
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a set of keys.
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Required property:
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sysrq-reset-seq: array of Linux keycodes, one keycode per cell.
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Optional property:
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timeout-ms: duration keys must be pressed together in milliseconds before
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generating a sysrq. If omitted the system is rebooted immediately when a valid
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sequence has been recognized.
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Example:
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chosen {
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linux,sysrq-reset-seq {
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keyset = <0x03
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0x04
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0x0a>;
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timeout-ms = <3000>;
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};
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};
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Would represent KEY_2, KEY_3 and KEY_9.
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@ -45,6 +45,7 @@
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#include <linux/moduleparam.h>
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#include <linux/jiffies.h>
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#include <linux/syscalls.h>
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#include <linux/of.h>
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#include <asm/ptrace.h>
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#include <asm/irq_regs.h>
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@ -681,6 +682,40 @@ static void sysrq_detect_reset_sequence(struct sysrq_state *state,
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}
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}
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#ifdef CONFIG_OF
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static void sysrq_of_get_keyreset_config(void)
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{
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u32 key;
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struct device_node *np;
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struct property *prop;
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const __be32 *p;
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np = of_find_node_by_path("/chosen/linux,sysrq-reset-seq");
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if (!np) {
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pr_debug("No sysrq node found");
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return;
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}
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/* Reset in case a __weak definition was present */
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sysrq_reset_seq_len = 0;
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of_property_for_each_u32(np, "keyset", prop, p, key) {
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if (key == KEY_RESERVED || key > KEY_MAX ||
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sysrq_reset_seq_len == SYSRQ_KEY_RESET_MAX)
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break;
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sysrq_reset_seq[sysrq_reset_seq_len++] = (unsigned short)key;
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}
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/* Get reset timeout if any. */
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of_property_read_u32(np, "timeout-ms", &sysrq_reset_downtime_ms);
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}
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#else
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static void sysrq_of_get_keyreset_config(void)
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{
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}
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#endif
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static void sysrq_reinject_alt_sysrq(struct work_struct *work)
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{
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struct sysrq_state *sysrq =
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@ -914,6 +949,7 @@ static inline void sysrq_register_handler(void)
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int error;
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int i;
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/* First check if a __weak interface was instantiated. */
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for (i = 0; i < ARRAY_SIZE(sysrq_reset_seq); i++) {
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key = platform_sysrq_reset_seq[i];
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if (key == KEY_RESERVED || key > KEY_MAX)
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@ -922,6 +958,12 @@ static inline void sysrq_register_handler(void)
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sysrq_reset_seq[sysrq_reset_seq_len++] = key;
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}
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/*
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* DT configuration takes precedence over anything that would
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* have been defined via the __weak interface.
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*/
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sysrq_of_get_keyreset_config();
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error = input_register_handler(&sysrq_handler);
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if (error)
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pr_err("Failed to register input handler, error %d", error);
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