nvme-apple: Add initial Apple SoC NVMe driver

Apple SoCs such as the M1 come with an embedded NVMe controller that
is not attached to any PCIe bus. Additionally, it doesn't conform
to the NVMe specification and requires a bunch of changes to command
submission and IOMMU configuration to work.

Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Sven Peter <sven@svenpeter.dev>

Author: svenpeter42

MAINTAINERS

@@ -1849,6 +1849,7 @@ F:	drivers/i2c/busses/i2c-pasemi-core.c
 F:	drivers/i2c/busses/i2c-pasemi-platform.c
 F:	drivers/irqchip/irq-apple-aic.c
 F:	drivers/mailbox/apple-mailbox.c
+F:	drivers/nvme/host/apple.c
 F:	drivers/pinctrl/pinctrl-apple-gpio.c
 F:	drivers/soc/apple/*
 F:	drivers/watchdog/apple_wdt.c

drivers/nvme/host/Kconfig

@@ -91,3 +91,16 @@ config NVME_TCP
 	  from https://github.com/linux-nvme/nvme-cli.
 
 	  If unsure, say N.
+
+config NVME_APPLE
+	tristate "Apple ANS2 NVM Express host driver"
+	depends on OF && BLOCK
+	depends on APPLE_RTKIT && APPLE_SART
+	depends on ARCH_APPLE || COMPILE_TEST
+	select NVME_CORE
+	help
+	  This provides support for the NVMe controller embedded in Apple SoCs
+	  such as the M1.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called nvme-apple.

drivers/nvme/host/Makefile

@@ -8,6 +8,7 @@ obj-$(CONFIG_NVME_FABRICS)		+= nvme-fabrics.o
 obj-$(CONFIG_NVME_RDMA)			+= nvme-rdma.o
 obj-$(CONFIG_NVME_FC)			+= nvme-fc.o
 obj-$(CONFIG_NVME_TCP)			+= nvme-tcp.o
+obj-$(CONFIG_NVME_APPLE)		+= nvme-apple.o
 
 nvme-core-y				:= core.o ioctl.o constants.o
 nvme-core-$(CONFIG_TRACING)		+= trace.o
@@ -25,3 +26,5 @@ nvme-rdma-y				+= rdma.o
 nvme-fc-y				+= fc.o
 
 nvme-tcp-y				+= tcp.o
+
+nvme-apple-y				+= apple.o