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rpmsg: Add driver_override device attribute for rpmsg_device
This patch adds "driver_override" device attribute for rpmsg_device which will allow users to explicitly specify the rpmsg_driver to be used via sysfs entry. The "driver_override" device attribute implemented here is very similar to "driver_override" implemented for platform, pci, and amba bus types. One important use-case of "driver_override" device attribute is to force use of rpmsg_chrdev driver for certain rpmsg_device instances. Signed-off-by: Anup Patel <anup@brainfault.org> Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
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@ -73,3 +73,23 @@ Description:
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This sysfs entry tells us whether the channel is a local
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server channel that is announced (values are either
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true or false).
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What: /sys/bus/rpmsg/devices/.../driver_override
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Date: April 2018
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KernelVersion: 4.18
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Contact: Bjorn Andersson <bjorn.andersson@linaro.org>
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Description:
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Every rpmsg device is a communication channel with a remote
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processor. Channels are identified by a textual name (see
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/sys/bus/rpmsg/devices/.../name above) and have a local
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("source") rpmsg address, and remote ("destination") rpmsg
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address.
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The listening entity (or client) which communicates with a
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remote processor is referred as rpmsg driver. The rpmsg device
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and rpmsg driver are matched based on rpmsg device name and
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rpmsg driver ID table.
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This sysfs entry allows the rpmsg driver for a rpmsg device
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to be specified which will override standard OF, ID table
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and name matching.
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@ -333,11 +333,49 @@ field##_show(struct device *dev, \
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} \
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static DEVICE_ATTR_RO(field);
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#define rpmsg_string_attr(field, member) \
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static ssize_t \
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field##_store(struct device *dev, struct device_attribute *attr, \
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const char *buf, size_t sz) \
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{ \
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struct rpmsg_device *rpdev = to_rpmsg_device(dev); \
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char *new, *old; \
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\
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new = kstrndup(buf, sz, GFP_KERNEL); \
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if (!new) \
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return -ENOMEM; \
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new[strcspn(new, "\n")] = '\0'; \
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\
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device_lock(dev); \
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old = rpdev->member; \
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if (strlen(new)) { \
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rpdev->member = new; \
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} else { \
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kfree(new); \
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rpdev->member = NULL; \
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} \
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device_unlock(dev); \
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\
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kfree(old); \
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\
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return sz; \
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} \
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static ssize_t \
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field##_show(struct device *dev, \
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struct device_attribute *attr, char *buf) \
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{ \
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struct rpmsg_device *rpdev = to_rpmsg_device(dev); \
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\
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return sprintf(buf, "%s\n", rpdev->member); \
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} \
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static DEVICE_ATTR_RW(field)
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/* for more info, see Documentation/ABI/testing/sysfs-bus-rpmsg */
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rpmsg_show_attr(name, id.name, "%s\n");
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rpmsg_show_attr(src, src, "0x%x\n");
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rpmsg_show_attr(dst, dst, "0x%x\n");
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rpmsg_show_attr(announce, announce ? "true" : "false", "%s\n");
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rpmsg_string_attr(driver_override, driver_override);
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static ssize_t modalias_show(struct device *dev,
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struct device_attribute *attr, char *buf)
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@ -359,6 +397,7 @@ static struct attribute *rpmsg_dev_attrs[] = {
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&dev_attr_dst.attr,
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&dev_attr_src.attr,
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&dev_attr_announce.attr,
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&dev_attr_driver_override.attr,
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NULL,
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};
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ATTRIBUTE_GROUPS(rpmsg_dev);
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