Shutdown U-Boot before starting an OS

Some devices, especially the ones doing DMA should be disabled before
giving control to an OS. We take the simple approach here: Just shutdown
the devices in the reverse order they were activated.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

arch/arm/cpu/cpu.c

@@ -141,6 +141,8 @@ int cleanup_before_linux (void)
 {
 	int i;
 
+	shutdown_uboot();
+
 	/* flush I/D-cache */
 	i = 0;
 	asm ("mcr p15, 0, %0, c7, c7, 0": :"r" (i));

common/startup.c

@@ -156,3 +156,13 @@ void hang (void)
 	puts ("### ERROR ### Please RESET the board ###\n");
 	for (;;);
 }
+
+/* Everything needed to cleanly shutdown U-Boot.
+ * Should be called before starting an OS to get
+ * the devices into a clean state
+ */
+void shutdown_uboot(void)
+{
+	devices_shutdown();
+}
+

include/common.h

@@ -131,6 +131,7 @@ int parse_area_spec(const char *str, ulong *start, ulong *size);
 unsigned long strtoul_suffix(const char *str, char **endp, int base);
 
 void start_uboot(void);
+void shutdown_uboot(void);
 
 int arch_execute(unsigned long address, int argc, char *argv[]);
 

include/driver.h

@@ -103,6 +103,7 @@ struct device_d {
 	struct list_head list;     /* The list of all devices */
 	struct list_head children; /* our children            */
 	struct list_head sibling;
+	struct list_head active;   /* The list of all devices which have a driver */
 
 	struct device_d *parent;   /* our parent, NULL if not present */
 
@@ -128,7 +129,7 @@ struct driver_d {
 	int     (*probe) (struct device_d *);
 
 	/*! Called if an instance of a device is gone. */
-	int     (*remove)(struct device_d *);
+	void     (*remove)(struct device_d *);
 
 	/*! Called in response of reading from this device. Required */
 	ssize_t (*read)  (struct device_d*, void* buf, size_t count, ulong offset, ulong flags);
@@ -245,6 +246,11 @@ int mem_memmap(struct device_d *dev, void **map, int flags);
 /* Use this if you have nothing to do in your drivers probe function */
 int dummy_probe(struct device_d *);
 
+/* Iterate over all activated devices (i.e. the ones with drivers and shut
+ * them down.
+ */
+void devices_shutdown(void);
+
 int generic_memmap_ro(struct device_d *dev, void **map, int flags);
 int generic_memmap_rw(struct device_d *dev, void **map, int flags);
 

lib/driver.c

@@ -40,6 +40,8 @@ EXPORT_SYMBOL(device_list);
 LIST_HEAD(driver_list);
 EXPORT_SYMBOL(driver_list);
 
+static LIST_HEAD(active);
+
 struct device_d *get_device_by_id(const char *id)
 {
 	struct device_d *dev;
@@ -77,6 +79,8 @@ static int match(struct driver_d *drv, struct device_d *dev)
 
 	dev->driver = drv;
 
+	list_add(&dev->active, &active);
+
 	return 0;
 }
 
@@ -326,6 +330,16 @@ const char *dev_id(const struct device_d *dev)
 	return buf;
 }
 
+void devices_shutdown(void)
+{
+	struct device_d *dev;
+
+	list_for_each_entry(dev, &active, active) {
+		if (dev->driver->remove)
+			dev->driver->remove(dev);
+	}
+}
+
 #ifdef CONFIG_CMD_DEVINFO
 
 static int do_devinfo ( cmd_tbl_t *cmdtp, int argc, char *argv[])