kernel/amd64: bus: Add bus resource interface

This commit introduces a bus resource abstraction. A bus resource
encapsulates bus specific information and semantics. Along with
abstracting away bus specific details and providing an overall
smoother interface, this additionally provides flexibility, access
control and security by keeping track of permissions and allowing
things to be turned on or off.

Signed-off-by: Ian Moffett <ian@osmora.org>

1 files changed, 57 insertions, 0 deletions

diff --git a/sys/include/arch/amd64/bus.h b/sys/include/arch/amd64/bus.h
index c99d13f..00cb3ba 100644
--- a/sys/include/arch/amd64/bus.h
+++ b/sys/include/arch/amd64/bus.h
@@ -31,6 +31,10 @@
 #define _MACHINE_BUS_H_
 
 #include <sys/types.h>
+#include <sys/spinlock.h>
+#include <sys/param.h>
+
+struct bus_resource;
 
 /*
  * Hyra assumes that the bootloader uses PDE[256] for some
@@ -40,8 +44,61 @@
  */
 #define MMIO_OFFSET (VM_HIGHER_HALF + 0x8000000000)
 
+/* Resource signature size max */
+#define RSIG_MAX 16
+
+/*
+ * Basic bus resource semantics
+ *
+ * BUS_PIO: If set, this resource uses port I/O
+ * BUS_MMIO: If set, this resource uses memory-mapped I/O
+ * BUS_WRITABLE: If unset, this resource is read-only
+ * BUS_DMA: If set, this resource is DMA-capable
+ */
+#define BUS_PIO       BIT(0)
+#define BUS_MMIO      BIT(1)
+#define BUS_WRITABLE  BIT(2)
+#define BUS_DMA       BIT(3)
+
+/*
+ * Common bus types.
+ *
+ * bus_addr_t: Physical MMIO address
+ * bus_sem_t: Resource semantics
+ */
 typedef uint64_t bus_addr_t;
+typedef uint64_t bus_sem_t;
+
+struct bus_op {
+    /* Enable/disable DMA */
+    int(*enable_dma)(struct bus_resource *brp, void *arg);
+    int(*disable_dma)(struct bus_resource *brp, void *arg);
+
+    /* Set/unset flags */
+    int(*set_sem)(struct bus_resource *brp, bus_sem_t sem);
+    int(*clr_sem)(struct bus_resource *brp, bus_sem_t sem);
+
+    /* DMA buffer related operations */
+    int(*dma_alloc)(struct bus_resource *brp, void *res);
+    int(*dma_free)(struct bus_resource *brp, void *p);
+
+    /* DMA transfer related operations */
+    ssize_t(*dma_in)(struct bus_resource *brp, void *p);
+    ssize_t(*dma_out)(struct bus_resource *brp, void *p);
+};
+
+struct bus_resource {
+    char signature[RSIG_MAX];   /* e.g., "PCI\0", "ISA\0", "LPC\0", etc */
+    off_t align;                /* Alignment required (0: none) */
+    bus_addr_t dma_max;         /* Maximum address possible for DMA */
+    bus_addr_t dma_min;         /* Minimum address possible for DMA */
+    bus_addr_t base;            /* Resource base [physical] address */
+    bus_sem_t sem;              /* Resource semantics */
+    struct bus_op io;           /* I/O operations */
+    struct spinlock lock;       /* Protects this structure */
+};
 
 int bus_map(bus_addr_t addr, size_t size, int flags, void **vap);
+struct bus_resource *bus_establish(const char *name);
 
 #endif  /* !_MACHINE_BUS_H_ */