[PATCH 07/13] remoteproc: Introduce function rproc_detach()

Mathieu Poirier
2020-08-26T16:48:21Z

Introduce function rproc_detach() to enable the remoteproc
core to release the resources associated with a remote processor
without stopping its operation.

Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
---
drivers/remoteproc/remoteproc_core.c | 65 +++++++++++++++++++++++++++-
include/linux/remoteproc.h | 1 +
2 files changed, 65 insertions(+), 1 deletion(-)

diff --git a/drivers/remoteproc/remoteproc_core.c b/drivers/remoteproc/remoteproc_core.c
index 7a1fc7e0620f..f3943a1e2754 100644
--- a/drivers/remoteproc/remoteproc_core.c
+++ b/drivers/remoteproc/remoteproc_core.c
@@ -1644,7 +1644,7 @@ static int rproc_stop(struct rproc *rproc, bool crashed)
/*
* __rproc_detach(): Does the opposite of rproc_attach()
*/
-static int __maybe_unused __rproc_detach(struct rproc *rproc)
+static int __rproc_detach(struct rproc *rproc)
{
struct device *dev = &rproc->dev;
int ret;
@@ -1887,6 +1887,69 @@ void rproc_shutdown(struct rproc *rproc)
}
EXPORT_SYMBOL(rproc_shutdown);

+/**
+ * rproc_detach() - Detach the remote processor from the
+ * remoteproc core
+ *
+ * @rproc: the remote processor
+ *
+ * Detach a remote processor (previously attached to with rproc_actuate()).
+ *
+ * In case @rproc is still being used by an additional user(s), then
+ * this function will just decrement the power refcount and exit,
+ * without disconnecting the device.
+ *
+ * Function rproc_detach() calls __rproc_detach() in order to let a remote
+ * processor know that services provided by the application processor are
+ * no longer available. From there it should be possible to remove the
+ * platform driver and even power cycle the application processor (if the HW
+ * supports it) without needing to switch off the remote processor.
+ */
+int rproc_detach(struct rproc *rproc)
+{
+ struct device *dev = &rproc->dev;
+ int ret;
+
+ ret = mutex_lock_interruptible(&rproc->lock);
+ if (ret) {
+ dev_err(dev, "can't lock rproc %s: %d\n", rproc->name, ret);
+ return ret;
+ }
+
+ if (rproc->state != RPROC_RUNNING && rproc->state != RPROC_ATTACHED) {
+ ret = -EPERM;
+ goto out;
+ }
+
+ /* if the remote proc is still needed, bail out */
+ if (!atomic_dec_and_test(&rproc->power)) {
+ ret = -EBUSY;
+ goto out;
+ }
+
+ ret = __rproc_detach(rproc);
+ if (ret) {
+ atomic_inc(&rproc->power);
+ goto out;
+ }
+
+ /* clean up all acquired resources */
+ rproc_resource_cleanup(rproc);
+
+ rproc_disable_iommu(rproc);
+
+ /*
+ * Set the remote processor's table pointer to NULL. Since mapping
+ * of the resource table to a virtual address is done in the platform
+ * driver, unmapping should also be done there.
+ */
+ rproc->table_ptr = NULL;
+out:
+ mutex_unlock(&rproc->lock);
+ return ret;
+}
+EXPORT_SYMBOL(rproc_detach);
+
/**
* rproc_get_by_phandle() - find a remote processor by phandle
* @phandle: phandle to the rproc
diff --git a/include/linux/remoteproc.h b/include/linux/remoteproc.h
index 1a57e165da2c..6250491ee851 100644
--- a/include/linux/remoteproc.h
+++ b/include/linux/remoteproc.h
@@ -656,6 +656,7 @@ rproc_of_resm_mem_entry_init(struct device *dev, u32 of_resm_idx, size_t len,

int rproc_boot(struct rproc *rproc);
void rproc_shutdown(struct rproc *rproc);
+int rproc_detach(struct rproc *rproc);
void rproc_report_crash(struct rproc *rproc, enum rproc_crash_type type);
int rproc_coredump_add_segment(struct rproc *rproc, dma_addr_t da, size_t size);
int rproc_coredump_add_custom_segment(struct rproc *rproc,
--
2.25.1