macintosh/via-pmu: Enhance state machine with new 'uninitialized' state

On 68k Macs, the via/vias pointer can't be used to determine whether
the PMU driver has been initialized. For portability, add a new state
to indicate that via_find_pmu() succeeded.

After via_find_pmu() executes, testing vias == NULL is equivalent to
testing via == NULL. Replace these tests with pmu_state == uninitialized
which is simpler and more consistent. No functional change.
Tested-by: Stan Johnson <userm57@yahoo.com>
Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

drivers/macintosh/via-pmu.c

@@ -114,6 +114,7 @@ static volatile unsigned char __iomem *via;
 #define CB1_INT		0x10		/* transition on CB1 input */
 
 static volatile enum pmu_state {
+	uninitialized = 0,
 	idle,
 	sending,
 	intack,
@@ -274,7 +275,7 @@ int __init find_via_pmu(void)
 	u64 taddr;
 	const u32 *reg;
 
-	if (via)
+	if (pmu_state != uninitialized)
 		return 1;
 	vias = of_find_node_by_name(NULL, "via-pmu");
 	if (vias == NULL)
@@ -369,20 +370,19 @@ int __init find_via_pmu(void)
  fail:
 	of_node_put(vias);
 	vias = NULL;
+	pmu_state = uninitialized;
 	return 0;
 }
 
 #ifdef CONFIG_ADB
 static int pmu_probe(void)
 {
-	return vias == NULL? -ENODEV: 0;
+	return pmu_state == uninitialized ? -ENODEV : 0;
 }
 
 static int pmu_init(void)
 {
-	if (vias == NULL)
-		return -ENODEV;
-	return 0;
+	return pmu_state == uninitialized ? -ENODEV : 0;
 }
 #endif /* CONFIG_ADB */
 
@@ -397,7 +397,7 @@ static int __init via_pmu_start(void)
 {
 	unsigned int irq;
 
-	if (vias == NULL)
+	if (pmu_state == uninitialized)
 		return -ENODEV;
 
 	batt_req.complete = 1;
@@ -463,7 +463,7 @@ arch_initcall(via_pmu_start);
  */
 static int __init via_pmu_dev_init(void)
 {
-	if (vias == NULL)
+	if (pmu_state == uninitialized)
 		return -ENODEV;
 
 #ifdef CONFIG_PMAC_BACKLIGHT
@@ -929,7 +929,7 @@ static int pmu_send_request(struct adb_request *req, int sync)
 {
 	int i, ret;
 
-	if ((vias == NULL) || (!pmu_fully_inited)) {
+	if (pmu_state == uninitialized || !pmu_fully_inited) {
 		req->complete = 1;
 		return -ENXIO;
 	}
@@ -1023,7 +1023,7 @@ static int __pmu_adb_autopoll(int devs)
 
 static int pmu_adb_autopoll(int devs)
 {
-	if ((vias == NULL) || (!pmu_fully_inited) || !pmu_has_adb)
+	if (pmu_state == uninitialized || !pmu_fully_inited || !pmu_has_adb)
 		return -ENXIO;
 
 	adb_dev_map = devs;
@@ -1036,7 +1036,7 @@ static int pmu_adb_reset_bus(void)
 	struct adb_request req;
 	int save_autopoll = adb_dev_map;
 
-	if ((vias == NULL) || (!pmu_fully_inited) || !pmu_has_adb)
+	if (pmu_state == uninitialized || !pmu_fully_inited || !pmu_has_adb)
 		return -ENXIO;
 
 	/* anyone got a better idea?? */
@@ -1072,7 +1072,7 @@ pmu_request(struct adb_request *req, void (*done)(struct adb_request *),
 	va_list list;
 	int i;
 
-	if (vias == NULL)
+	if (pmu_state == uninitialized)
 		return -ENXIO;
 
 	if (nbytes < 0 || nbytes > 32) {
@@ -1097,7 +1097,7 @@ pmu_queue_request(struct adb_request *req)
 	unsigned long flags;
 	int nsend;
 
-	if (via == NULL) {
+	if (pmu_state == uninitialized) {
 		req->complete = 1;
 		return -ENXIO;
 	}
@@ -1210,7 +1210,7 @@ pmu_start(void)
 void
 pmu_poll(void)
 {
-	if (!via)
+	if (pmu_state == uninitialized)
 		return;
 	if (disable_poll)
 		return;
@@ -1220,7 +1220,7 @@ pmu_poll(void)
 void
 pmu_poll_adb(void)
 {
-	if (!via)
+	if (pmu_state == uninitialized)
 		return;
 	if (disable_poll)
 		return;
@@ -1235,7 +1235,7 @@ pmu_poll_adb(void)
 void
 pmu_wait_complete(struct adb_request *req)
 {
-	if (!via)
+	if (pmu_state == uninitialized)
 		return;
 	while((pmu_state != idle && pmu_state != locked) || !req->complete)
 		via_pmu_interrupt(0, NULL);
@@ -1251,7 +1251,7 @@ pmu_suspend(void)
 {
 	unsigned long flags;
 
-	if (!via)
+	if (pmu_state == uninitialized)
 		return;
 	
 	spin_lock_irqsave(&pmu_lock, flags);
@@ -1282,7 +1282,7 @@ pmu_resume(void)
 {
 	unsigned long flags;
 
-	if (!via || (pmu_suspended < 1))
+	if (pmu_state == uninitialized || pmu_suspended < 1)
 		return;
 
 	spin_lock_irqsave(&pmu_lock, flags);
@@ -1644,7 +1644,7 @@ pmu_enable_irled(int on)
 {
 	struct adb_request req;
 
-	if (vias == NULL)
+	if (pmu_state == uninitialized)
 		return ;
 	if (pmu_kind == PMU_KEYLARGO_BASED)
 		return ;
@@ -1659,7 +1659,7 @@ pmu_restart(void)
 {
 	struct adb_request req;
 
-	if (via == NULL)
+	if (pmu_state == uninitialized)
 		return;
 
 	local_irq_disable();
@@ -1684,7 +1684,7 @@ pmu_shutdown(void)
 {
 	struct adb_request req;
 
-	if (via == NULL)
+	if (pmu_state == uninitialized)
 		return;
 
 	local_irq_disable();
@@ -1712,7 +1712,7 @@ pmu_shutdown(void)
 int
 pmu_present(void)
 {
-	return via != NULL;
+	return pmu_state != uninitialized;
 }
 
 #if defined(CONFIG_SUSPEND) && defined(CONFIG_PPC32)
@@ -2378,7 +2378,7 @@ static struct miscdevice pmu_device = {
 
 static int pmu_device_init(void)
 {
-	if (!via)
+	if (pmu_state == uninitialized)
 		return 0;
 	if (misc_register(&pmu_device) < 0)
 		printk(KERN_ERR "via-pmu: cannot register misc device.\n");