Dear all, I'm trying to create a simple sysfs node that prints the content of a register. The code looks like this static ssize_t my_read_reg(struct device *pdev, struct device_attribute *attr, char *buf) { u32 __iomem *reg; reg = devm_ioremap(pdev, 0x581018C4, 4); return scnprintf(buf, PAGE_SIZE, "0x%02x\n", ioread8(reg)); } Is it ok to use devm_ioremap() on the device that I get here? If so, may I assume that devm_ioremap() re-uses an existing mapping and it's ok to call it for each sysfs access? The physical address that I pass to devm_ioremap() is not page-aligned. This seems to work on arm. Is there a recommended (i.e. more portable) way of doing this? Should I map a larger area and use PAGE_ALIGN()? Thanks for your feedback, Martin