hw/ipmi: Disable flash access when requested

BMC based systems contain a PNOR to provide flash storage. The host
normally has exclusive access to the PNOR, however the BMC may use IPMI
to request access to perform functions such as update the firmware.

Indicate to users of the flash that the device is busy by taking the
lock, and setting a per-flash busy flag, which causes flash operations
to return OPAL_BUSY.

Minor changes from Jeremy Kerr

Signed-off-by: Joel Stanley <joel@jms.id.au>
Signed-off-by: Jeremy Kerr <jk@ozlabs.org>

1 files changed, 54 insertions, 4 deletions

diff --git a/core/flash.c b/core/flash.c
index 3a06d1d..9912add 100644
--- a/core/flash.c
+++ b/core/flash.c
@@ -26,6 +26,7 @@
 
 struct flash {
 	bool			registered;
+	bool			busy;
 	struct flash_chip	*chip;
 	uint32_t		size;
 	uint32_t		block_size;
@@ -42,12 +43,39 @@ static struct lock flash_lock;
 static struct flash *nvram_flash;
 static u32 nvram_offset, nvram_size;
 
+bool flash_reserve(void)
+{
+	bool rc = false;
+
+	if (!try_lock(&flash_lock))
+		return false;
+
+	if (!system_flash->busy) {
+		system_flash->busy = true;
+		rc = true;
+	}
+	unlock(&flash_lock);
+
+	return rc;
+}
+
+void flash_release(void)
+{
+	lock(&flash_lock);
+	system_flash->busy = false;
+	unlock(&flash_lock);
+}
+
 static int flash_nvram_info(uint32_t *total_size)
 {
-	int rc = OPAL_HARDWARE;
+	int rc;
 
 	lock(&flash_lock);
-	if (nvram_flash) {
+	if (!nvram_flash) {
+		rc = OPAL_HARDWARE;
+	} else if (nvram_flash->busy) {
+		rc = OPAL_BUSY;
+	} else {
 		*total_size = nvram_size;
 		rc = OPAL_SUCCESS;
 	}
@@ -60,13 +88,19 @@ static int flash_nvram_start_read(void *dst, uint32_t src, uint32_t len)
 {
 	int rc;
 
-	lock(&flash_lock);
+	if (!try_lock(&flash_lock))
+		return OPAL_BUSY;
 
 	if (!nvram_flash) {
 		rc = OPAL_HARDWARE;
 		goto out;
 	}
 
+	if (nvram_flash->busy) {
+		rc = OPAL_BUSY;
+		goto out;
+	}
+
 	if ((src + len) > nvram_size) {
 		prerror("FLASH_NVRAM: read out of bound (0x%x,0x%x)\n",
 			src, len);
@@ -87,7 +121,13 @@ static int flash_nvram_write(uint32_t dst, void *src, uint32_t len)
 {
 	int rc;
 
-	lock(&flash_lock);
+	if (try_lock(&flash_lock))
+		return OPAL_BUSY;
+
+	if (nvram_flash->busy) {
+		rc = OPAL_BUSY;
+		goto out;
+	}
 
 	/* TODO: When we have async jobs for PRD, turn this into one */
 
@@ -235,6 +275,7 @@ int flash_register(struct flash_chip *chip, bool is_system_flash)
 
 		flash = &flashes[i];
 		flash->registered = true;
+		flash->busy = false;
 		flash->chip = chip;
 		flash->size = size;
 		flash->block_size = block_size;
@@ -286,6 +327,12 @@ static int64_t opal_flash_op(enum flash_op op, uint64_t id, uint64_t offset,
 		return OPAL_BUSY;
 
 	flash = &flashes[id];
+
+	if (flash->busy) {
+		rc = OPAL_BUSY;
+		goto err;
+	}
+
 	if (!flash->registered) {
 		rc = OPAL_PARAMETER;
 		goto err;
@@ -493,6 +540,9 @@ bool flash_load_resource(enum resource_id id, uint32_t subid,
 
 	flash = system_flash;
 
+	if (flash->busy)
+		goto out_unlock;
+
 	for (i = 0, name = NULL; i < ARRAY_SIZE(part_name_map); i++) {
 		if (part_name_map[i].id == id) {
 			name = part_name_map[i].name;