remoteproc: Properly deal with a start request when attached

This patch takes into account scenarios where a remote processor
has been attached to when receiving a "start" command from sysfs.

As with the case with the running state, the command can't be
carried out if the remote processor is already in operation.
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Reviewed-by: Arnaud Pouliquen <arnaud.pouliquen@st.com>
Link: https://lore.kernel.org/r/20210312162453.1234145-15-mathieu.poirier@linaro.orgSigned-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>

drivers/remoteproc/remoteproc_cdev.c

@@ -32,7 +32,8 @@ static ssize_t rproc_cdev_write(struct file *filp, const char __user *buf, size_
 		return -EFAULT;
 
 	if (!strncmp(cmd, "start", len)) {
-		if (rproc->state == RPROC_RUNNING)
+		if (rproc->state == RPROC_RUNNING ||
+		    rproc->state == RPROC_ATTACHED)
 			return -EBUSY;
 
 		ret = rproc_boot(rproc);

drivers/remoteproc/remoteproc_sysfs.c

@@ -194,7 +194,8 @@ static ssize_t state_store(struct device *dev,
 	int ret = 0;
 
 	if (sysfs_streq(buf, "start")) {
-		if (rproc->state == RPROC_RUNNING)
+		if (rproc->state == RPROC_RUNNING ||
+		    rproc->state == RPROC_ATTACHED)
 			return -EBUSY;
 
 		ret = rproc_boot(rproc);