habanalabs: revise and document use of boot status flags

The boot status flag "SRAM available" can be set by f/w Linux (in the
general case) or by f/w uboot (in some specific debug scenario) but
never by f/w preboot.

Hence, when polling the boot status flags in the preboot stage we do not
want to poll on "SRAM Avialable".

The special case in which uboot set this flag is when we are running
special debug scenario without Linux. In this case, at some point during
the boot, the uboot relocates its code to the DRAM and then set the
specified flag.
Signed-off-by: Ohad Sharabi <osharabi@habana.ai>
Reviewed-by: Oded Gabbay <ogabbay@kernel.org>
Signed-off-by: Oded Gabbay <ogabbay@kernel.org>

drivers/misc/habanalabs/common/firmware_if.c

@@ -1101,7 +1101,6 @@ static int hl_fw_read_preboot_caps(struct hl_device *hdev,
 		(status == CPU_BOOT_STATUS_DRAM_RDY) ||
 		(status == CPU_BOOT_STATUS_NIC_FW_RDY) ||
 		(status == CPU_BOOT_STATUS_READY_TO_BOOT) ||
-		(status == CPU_BOOT_STATUS_SRAM_AVAIL) ||
 		(status == CPU_BOOT_STATUS_WAITING_FOR_BOOT_FIT),
 		FW_CPU_STATUS_POLL_INTERVAL_USEC,
 		timeout);
@@ -2055,12 +2054,20 @@ static int hl_fw_dynamic_wait_for_boot_fit_active(struct hl_device *hdev,
 
 	dyn_loader = &fw_loader->dynamic_loader;
 
-	/* Make sure CPU boot-loader is running */
+	/*
+	 * Make sure CPU boot-loader is running
+	 * Note that the CPU_BOOT_STATUS_SRAM_AVAIL is generally set by Linux
+	 * yet there is a debug scenario in which we loading uboot (without Linux)
+	 * which at later stage is relocated to DRAM. In this case we expect
+	 * uboot to set the CPU_BOOT_STATUS_SRAM_AVAIL and so we add it to the
+	 * poll flags
+	 */
 	rc = hl_poll_timeout(
 		hdev,
 		le32_to_cpu(dyn_loader->comm_desc.cpu_dyn_regs.cpu_boot_status),
 		status,
-		(status == CPU_BOOT_STATUS_READY_TO_BOOT),
+		(status == CPU_BOOT_STATUS_READY_TO_BOOT) ||
+		(status == CPU_BOOT_STATUS_SRAM_AVAIL),
 		FW_CPU_STATUS_POLL_INTERVAL_USEC,
 		dyn_loader->wait_for_bl_timeout);
 	if (rc) {
@@ -2081,7 +2088,7 @@ static int hl_fw_dynamic_wait_for_linux_active(struct hl_device *hdev,
 
 	dyn_loader = &fw_loader->dynamic_loader;
 
-	/* Make sure CPU boot-loader is running */
+	/* Make sure CPU linux is running */
 
 	rc = hl_poll_timeout(
 		hdev,
@@ -2415,7 +2422,14 @@ static int hl_fw_static_init_cpu(struct hl_device *hdev,
 		WREG32(msg_to_cpu_reg, KMD_MSG_NA);
 	}
 
-	/* Make sure CPU boot-loader is running */
+	/*
+	 * Make sure CPU boot-loader is running
+	 * Note that the CPU_BOOT_STATUS_SRAM_AVAIL is generally set by Linux
+	 * yet there is a debug scenario in which we loading uboot (without Linux)
+	 * which at later stage is relocated to DRAM. In this case we expect
+	 * uboot to set the CPU_BOOT_STATUS_SRAM_AVAIL and so we add it to the
+	 * poll flags
+	 */
 	rc = hl_poll_timeout(
 		hdev,
 		cpu_boot_status_reg,