implement dmem semi-properlyHEADmaster

+ Add tests and fix virtual mapping, this is enough to start writing
  proper userspace drivers

3 files changed, 28 insertions, 2 deletions

diff --git a/include/kmi/dmem.h b/include/kmi/dmem.h
index 697e55a..ec3e330 100644
--- a/include/kmi/dmem.h
+++ b/include/kmi/dmem.h
@@ -41,10 +41,33 @@ vm_t alloc_devmem(struct tcb *p, pm_t dev_start, size_t bytes, vmflags_t flags);
 /**
  * Free direct device mapping.
  *
+ * Frees both the uvmem and the underlying physical
+ * memory, can be called from syscall handler for example.
+ *
  * @param p Process to free mapping from.
  * @param dev_start Start of allocation.
  * @return \ref OK when succesful, \c ERR_NF when mapping not found.
  */
 stat_t free_devmem(struct tcb *p, vm_t dev_start);
 
+/**
+ * Free direct device mapping when the memory region is known.
+ *
+ * Arguably this means that the responsibilities of uvmem/vmem/dmem are not as
+ * nicely defined as I would like and they all kind of step on eachother's toes
+ * at the moment but good enough for right now, allows starting to write drivers in
+ * userspace.
+ *
+ * Note that at least currently this function has some strong assumptions about
+ * when it can be called, namely that the process must own the region and that
+ * there can be no external references to it. In other words, should only be
+ * called when the underlying physical memory should be freed.
+ * Does NOT free the uvmem of the region, only the underlying physical memory.
+ *
+ * @param p Process to free mapping from.
+ * @param m Memory region previously known to be a device memory mapping.
+ * @return \ref OK when succesful, \c ERR_INVAL otherwise.
+ */
+stat_t free_known_devmem(struct tcb *p, struct mem_region *m);
+
 #endif /* KMI_DEV_H */
diff --git a/include/kmi/mem.h b/include/kmi/mem.h
index 8c66eb5..129ae5e 100644
--- a/include/kmi/mem.h
+++ b/include/kmi/mem.h
@@ -188,6 +188,9 @@ size_t page_shift();
 /** Memory region is private but not backed by memory. */
 #define MR_NONBACKED (1 << (ARCH_VP_FLAGS + 3))
 
+/** Memory region in device memory region */
+#define MR_DEV (1 << (ARCH_VP_FLAGS + 4))
+
 /** @} */
 
 /**
diff --git a/include/kmi/syscalls.h b/include/kmi/syscalls.h
index 30e46be..8921343 100644
--- a/include/kmi/syscalls.h
+++ b/include/kmi/syscalls.h
@@ -47,8 +47,8 @@ enum sys_code {
 	/** Request memory from anywhere. */
 	SYS_REQ_MEM,
 
-	/** Request memory with physical address. */
-	SYS_REQ_PMEM,
+	/** Request device memory, i.e. some physical address outside RAM. */
+	SYS_REQ_DMEM,
 
 	/** Request memory at fixed virtual address. */
 	SYS_REQ_FIXMEM,