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Date: Mon, 27 Aug 2012 16:34:18 -0700
From: Randy Dunlap <rdunlap@...otime.net>
To: mathieu.poirier@...aro.org
CC: linux-kernel@...r.kernel.org, arve@...roid.com,
kernel-team@...roid.com, dmitry.torokhov@...il.com,
john.stultz@...aro.org
Subject: Re: [PATCH] drivers/tty: Folding Android's keyreset driver in sysRQ
On 08/27/2012 02:43 PM, mathieu.poirier@...aro.org wrote:
> From: "Mathieu J. Poirier" <mathieu.poirier@...aro.org>
>
> This patch adds keyreset functionality to the sysrq driver. It
> allows certain button/key combinations to be used in order to
> trigger device resets.
>
Please document what button/key combinations those are.
> The first time the key-combo is detected a work function that syncs
> the filesystems is scheduled and the kernel rebooted. If all the keys
> are released and then pressed again, it calls panic. Reboot on panic
> should be set for this to work. A platform device that specify a
> reset key-combo should be added to the board file to trigger the
> feature.
>
> This functionality comes from the keyreset driver submitted by
> Arve Hjønnevåg in the Android kernel.
>
> Cc: arve@...roid.com
> Cc: kernel-team@...roid.com
> Cc: dmitry.torokhov@...il.com
> Cc: john.stultz@...aro.org
> Signed-off-by: Mathieu Poirier <mathieu.poirier@...aro.org>
> ---
> drivers/tty/sysrq.c | 159 +++++++++++++++++++++++++++++++++++++++++++++++++
> include/linux/sysrq.h | 8 +++
> 2 files changed, 167 insertions(+), 0 deletions(-)
>
> diff --git a/drivers/tty/sysrq.c b/drivers/tty/sysrq.c
> index 05728894..6cf5531 100644
> --- a/drivers/tty/sysrq.c
> +++ b/drivers/tty/sysrq.c
> @@ -41,6 +41,9 @@
> #include <linux/slab.h>
> #include <linux/input.h>
> #include <linux/uaccess.h>
> +#include <linux/platform_device.h>
> +#include <linux/syscalls.h>
> +#include <linux/atomic.h>
>
> #include <asm/ptrace.h>
> #include <asm/irq_regs.h>
> @@ -49,6 +52,11 @@
> static int __read_mostly sysrq_enabled = SYSRQ_DEFAULT_ENABLE;
> static bool __read_mostly sysrq_always_enabled;
>
> +static struct input_handler sysrq_handler;
> +
> +/* Keep track of what has been called */
> +static atomic_t restart_requested;
> +
> static bool sysrq_on(void)
> {
> return sysrq_enabled || sysrq_always_enabled;
> @@ -570,6 +578,15 @@ struct sysrq_state {
> struct input_handle handle;
> struct work_struct reinject_work;
> unsigned long key_down[BITS_TO_LONGS(KEY_CNT)];
> + unsigned long keybit[BITS_TO_LONGS(KEY_CNT)];
> + unsigned long upbit[BITS_TO_LONGS(KEY_CNT)];
> + unsigned long key[BITS_TO_LONGS(KEY_CNT)];
> + int (*reset_fn)(void);
> + int key_down_target;
> + int key_down_ctn;
> + int key_up_ctn;
> + int keyreset_data;
> + int restart_disabled;
> unsigned int alt;
> unsigned int alt_use;
> bool active;
> @@ -603,6 +620,92 @@ static void sysrq_reinject_alt_sysrq(struct work_struct *work)
> }
> }
>
> +
> +static int sysrq_probe(struct platform_device *pdev)
> +{
> + struct keyreset_platform_data *pdata = pdev->dev.platform_data;
> +
> + /* No sequence of keys to trigger on,
> + * assuming default sysRQ behavior.
> + */
multi-line comment style not in kernel style.
> + if (pdata) {
> + atomic_set(&restart_requested, 0);
> + sysrq_handler.private = pdata;
> + } else
> + sysrq_handler.private = NULL;
> +
> + /* FETCH DT INFO HERE */
> +
> + return 0;
> +
> +}
> +
> +static void deferred_restart(struct work_struct *dummy)
> +{
> + atomic_inc(&restart_requested);
> + sys_sync();
> + atomic_inc(&restart_requested);
> + kernel_restart(NULL);
> +}
> +static DECLARE_WORK(restart_work, deferred_restart);
> +
> +static int do_keyreset_event(struct sysrq_state *state,
> + unsigned int code, int value)
> +{
> + int ret;
> + int processed = 0;
> +
> + /* Is the code is of interestest to us */
of interest to us */
> + if (!test_bit(code, state->keybit))
> + return processed;
> +
> + /* No need to take care of key up events */
> + if (!test_bit(code, state->key) == !value)
> + return processed;
> +
> + /* Record new entry */
> + __change_bit(code, state->key);
> +
> + processed = 1;
> +
> + if (test_bit(code, state->upbit)) {
> + if (value) {
> + state->restart_disabled = 1;
> + state->key_up_ctn++;
> + } else
> + state->key_up_ctn--;
> + } else {
> + if (value)
> + state->key_down_ctn++;
> + else
> + state->key_down_ctn--;
> + }
> +
> + if (state->key_down_ctn == 0 && state->key_up_ctn == 0)
> + state->restart_disabled = 0;
> +
> + if (value && !state->restart_disabled &&
> + state->key_down_ctn == state->key_down_target) {
> + state->restart_disabled = 1;
> + if (atomic_read(&restart_requested))
> + panic("keyboard reset failed, %d - panic\n",
> + atomic_read(&restart_requested));
> + if (state->reset_fn) {
> + ret = state->reset_fn();
> + atomic_set(&restart_requested, ret);
> + } else {
> + pr_info("keyboard reset\n");
> + schedule_work(&restart_work);
> + atomic_inc(&restart_requested);
> + }
> + }
> +
> + /* no need to suppress keyreset characters */
> + state->active = false;
> +
> + return processed;
> +}
> +
> static bool sysrq_filter(struct input_handle *handle,
> unsigned int type, unsigned int code, int value)
> {
> @@ -669,6 +772,11 @@ static bool sysrq_filter(struct input_handle *handle,
> if (sysrq->active && value && value != 2) {
> sysrq->need_reinject = false;
> __handle_sysrq(sysrq_xlate[code], true);
> + } else if (sysrq->keyreset_data) {
> + if (do_keyreset_event(sysrq, code, value)) {
> + suppress = sysrq->active;
> + goto end;
> + }
> }
> break;
> }
> @@ -704,9 +812,44 @@ static bool sysrq_filter(struct input_handle *handle,
> break;
> }
>
> + /*
> + * suppress == true - suppress passing to other subsystems.
> + * suppress == false - passing to other subsystems.
> + */
> +end:
> return suppress;
> }
>
> +static void parse_platform_data(struct sysrq_state *sysrq)
> +{
> + int key, *keyp;
> + struct keyreset_platform_data *pdata = sysrq_handler.private;
> +
> +
> + keyp = pdata->keys_down;
> + while ((key = *keyp++)) {
> + if (key >= KEY_MAX)
> + continue;
> + sysrq->key_down_target++;
> + __set_bit(key, sysrq->keybit);
> + }
> +
> + if (pdata->keys_up) {
> + keyp = pdata->keys_up;
> + while ((key = *keyp++)) {
> + if (key >= KEY_MAX)
> + continue;
> + __set_bit(key, sysrq->keybit);
> + __set_bit(key, sysrq->upbit);
> + }
> + }
> +
> + if (pdata->reset_fn)
> + sysrq->reset_fn = pdata->reset_fn;
> +
> + sysrq->keyreset_data = 1;
> +}
> +
> static int sysrq_connect(struct input_handler *handler,
> struct input_dev *dev,
> const struct input_device_id *id)
> @@ -718,6 +861,13 @@ static int sysrq_connect(struct input_handler *handler,
> if (!sysrq)
> return -ENOMEM;
>
> + /* input_register_handle() calls sysrq_probe(), who
> + * in turn will put the keyreset information in
> + * sysrq_handler's private field.
> + */
Use kernel multi-line comment style.
> + if (handler->private)
> + parse_platform_data(sysrq);
> +
> INIT_WORK(&sysrq->reinject_work, sysrq_reinject_alt_sysrq);
>
> sysrq->handle.dev = dev;
> @@ -780,12 +930,21 @@ static struct input_handler sysrq_handler = {
> .id_table = sysrq_ids,
> };
>
> +struct platform_driver sysrq_driver = {
> + .driver.name = SYSRQ_KRESET_NAME,
> + .probe = sysrq_probe,
> +};
> +
> static bool sysrq_handler_registered;
>
> static inline void sysrq_register_handler(void)
> {
> int error;
>
> + error = platform_driver_register(&sysrq_driver);
> + if (error)
> + pr_err("Failed to sysrq_keyreset driver, error %d", error);
Failed to register ...
> +
> error = input_register_handler(&sysrq_handler);
> if (error)
> pr_err("Failed to register input handler, error %d", error);
> diff --git a/include/linux/sysrq.h b/include/linux/sysrq.h
> index 7faf933..d470ae5 100644
> --- a/include/linux/sysrq.h
> +++ b/include/linux/sysrq.h
> @@ -17,6 +17,8 @@
> #include <linux/errno.h>
> #include <linux/types.h>
>
> +#define SYSRQ_KRESET_NAME "keyreset"
> +
> /* Enable/disable SYSRQ support by default (0==no, 1==yes). */
> #define SYSRQ_DEFAULT_ENABLE 1
>
> @@ -38,6 +40,12 @@ struct sysrq_key_op {
> int enable_mask;
> };
>
> +struct keyreset_platform_data {
> + int (*reset_fn)(void);
> + int *keys_up;
> + int keys_down[]; /* 0 terminated */
> +};
> +
> #ifdef CONFIG_MAGIC_SYSRQ
>
> /* Generic SysRq interface -- you may call it from any device driver, supplying
--
~Randy
--
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