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    Subject[PATCH 2/6] remoteproc: Add support for detach-only during shutdown
    Date
    The remoteproc core has support for both stopping and detaching a
    remote processor that was attached to previously, through both the
    remoteproc sysfs and cdev interfaces. The rproc_shutdown() though
    unconditionally only uses the stop functionality at present. This
    may not be the default desired functionality for all the remoteproc
    platform drivers.

    Introduce a new rproc state flag 'detach_on_shutdown' that individual
    remoteproc drivers can set to only allow detach in rproc_shutdown()
    that would have been invoked when the driver is uninstalled, so that
    remote processor continues to run undisturbed even after the driver
    removal.

    Signed-off-by: Suman Anna <s-anna@ti.com>
    ---
    drivers/remoteproc/remoteproc_cdev.c | 7 +++++++
    drivers/remoteproc/remoteproc_core.c | 5 ++++-
    drivers/remoteproc/remoteproc_sysfs.c | 6 ++++++
    include/linux/remoteproc.h | 3 +++
    4 files changed, 20 insertions(+), 1 deletion(-)

    diff --git a/drivers/remoteproc/remoteproc_cdev.c b/drivers/remoteproc/remoteproc_cdev.c
    index 0b8a84c04f76..473467711a09 100644
    --- a/drivers/remoteproc/remoteproc_cdev.c
    +++ b/drivers/remoteproc/remoteproc_cdev.c
    @@ -42,6 +42,13 @@ static ssize_t rproc_cdev_write(struct file *filp, const char __user *buf, size_
    rproc->state != RPROC_ATTACHED)
    return -EINVAL;

    + if (rproc->state == RPROC_ATTACHED &&
    + rproc->detach_on_shutdown) {
    + dev_err(&rproc->dev,
    + "stop not supported for this rproc, use detach\n");
    + return -EINVAL;
    + }
    +
    rproc_shutdown(rproc);
    } else if (!strncmp(cmd, "detach", len)) {
    if (rproc->state != RPROC_ATTACHED)
    diff --git a/drivers/remoteproc/remoteproc_core.c b/drivers/remoteproc/remoteproc_core.c
    index 6019f46001c8..e8ab3eb41f00 100644
    --- a/drivers/remoteproc/remoteproc_core.c
    +++ b/drivers/remoteproc/remoteproc_core.c
    @@ -2074,7 +2074,10 @@ void rproc_shutdown(struct rproc *rproc)
    if (!atomic_dec_and_test(&rproc->power))
    goto out;

    - ret = rproc_stop(rproc, false);
    + if (rproc->detach_on_shutdown && rproc->state == RPROC_ATTACHED)
    + ret = __rproc_detach(rproc);
    + else
    + ret = rproc_stop(rproc, false);
    if (ret) {
    atomic_inc(&rproc->power);
    goto out;
    diff --git a/drivers/remoteproc/remoteproc_sysfs.c b/drivers/remoteproc/remoteproc_sysfs.c
    index ea8b89f97d7b..1785fbcb1075 100644
    --- a/drivers/remoteproc/remoteproc_sysfs.c
    +++ b/drivers/remoteproc/remoteproc_sysfs.c
    @@ -206,6 +206,12 @@ static ssize_t state_store(struct device *dev,
    rproc->state != RPROC_ATTACHED)
    return -EINVAL;

    + if (rproc->state == RPROC_ATTACHED &&
    + rproc->detach_on_shutdown) {
    + dev_err(&rproc->dev, "stop not supported for this rproc, use detach\n");
    + return -EINVAL;
    + }
    +
    rproc_shutdown(rproc);
    } else if (sysfs_streq(buf, "detach")) {
    if (rproc->state != RPROC_ATTACHED)
    diff --git a/include/linux/remoteproc.h b/include/linux/remoteproc.h
    index 42a1f30e33a7..35ef921676a1 100644
    --- a/include/linux/remoteproc.h
    +++ b/include/linux/remoteproc.h
    @@ -530,6 +530,8 @@ struct rproc_dump_segment {
    * @elf_machine: firmware ELF machine
    * @cdev: character device of the rproc
    * @cdev_put_on_release: flag to indicate if remoteproc should be shutdown on @char_dev release
    + * @detach_on_shutdown: flag to indicate if remoteproc cannot be shutdown in
    + * attached state and _only_ support detach
    */
    struct rproc {
    struct list_head node;
    @@ -569,6 +571,7 @@ struct rproc {
    u16 elf_machine;
    struct cdev cdev;
    bool cdev_put_on_release;
    + bool detach_on_shutdown;
    };

    /**
    --
    2.30.1
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