nvme: apple: Add driver for Apple NVMe storage controller

Add a driver for the NVMe storage controller integrated on
Apple SoCs.  This NVMe controller isn't PCI based and deviates
from the NVMe standard in its implementation of the command
submission queue and the integration of an NVMMU that needs
to be managed.  This commit tweaks the core NVMe code to
support the linear command submission queue implemented by
this controller.  But setting up the submission queue and
managing the NVMMU controller is handled by implementing
the driver ops that were added in an earlier commit.

Signed-off-by: Mark Kettenis <kettenis@openbsd.org>
Tested-on: firefly-rk3399
Tested-by: Mark Kettenis <kettenis@openbsd.org>
Tested on: Macbook Air M1
Tested-by: Simon Glass <sjg@chromium.org>

3 files changed, 252 insertions, 0 deletions

diff --git a/drivers/nvme/Kconfig b/drivers/nvme/Kconfig
index 78da444c8b..0cb465160b 100644
--- a/drivers/nvme/Kconfig
+++ b/drivers/nvme/Kconfig
@@ -10,6 +10,17 @@ config NVME
 	  This option enables support for NVM Express devices.
 	  It supports basic functions of NVMe (read/write).
 
+config NVME_APPLE
+	bool "Apple NVMe controller support"
+	select NVME
+	help
+	  This option enables support for the NVMe storage
+	  controller integrated on Apple SoCs.  This controller
+	  isn't PCI-based based and deviates from the NVMe
+	  standard implementation in its implementation of
+	  the command submission queue and the integration
+	  of an NVMMU that needs to be managed.
+
 config NVME_PCI
 	bool "NVM Express PCI device support"
 	depends on PCI
diff --git a/drivers/nvme/Makefile b/drivers/nvme/Makefile
index fad9724e17..fa7b619446 100644
--- a/drivers/nvme/Makefile
+++ b/drivers/nvme/Makefile
@@ -3,4 +3,5 @@
 # Copyright (C) 2017, Bin Meng <bmeng.cn@gmail.com>
 
 obj-y += nvme-uclass.o nvme.o nvme_show.o
+obj-$(CONFIG_NVME_APPLE) += nvme_apple.o
 obj-$(CONFIG_NVME_PCI) += nvme_pci.o
diff --git a/drivers/nvme/nvme_apple.c b/drivers/nvme/nvme_apple.c
new file mode 100644
index 0000000000..d9d491c2be
--- /dev/null
+++ b/drivers/nvme/nvme_apple.c
@@ -0,0 +1,240 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * (C) Copyright 2021 Mark Kettenis <kettenis@openbsd.org>
+ */
+
+#include <common.h>
+#include <dm.h>
+#include <mailbox.h>
+#include <mapmem.h>
+#include "nvme.h"
+#include <reset.h>
+
+#include <asm/io.h>
+#include <asm/arch/rtkit.h>
+#include <linux/iopoll.h>
+
+/* ASC registers */
+#define REG_CPU_CTRL		0x0044
+#define  REG_CPU_CTRL_RUN	BIT(4)
+
+/* Apple NVMe registers */
+#define ANS_MAX_PEND_CMDS_CTRL	0x01210
+#define  ANS_MAX_QUEUE_DEPTH	64
+#define ANS_BOOT_STATUS		0x01300
+#define  ANS_BOOT_STATUS_OK	0xde71ce55
+#define ANS_MODESEL		0x01304
+#define ANS_UNKNOWN_CTRL	0x24008
+#define  ANS_PRP_NULL_CHECK	(1 << 11)
+#define ANS_LINEAR_SQ_CTRL	0x24908
+#define  ANS_LINEAR_SQ_CTRL_EN	(1 << 0)
+#define ANS_ASQ_DB		0x2490c
+#define ANS_IOSQ_DB		0x24910
+#define ANS_NVMMU_NUM		0x28100
+#define ANS_NVMMU_BASE_ASQ	0x28108
+#define ANS_NVMMU_BASE_IOSQ	0x28110
+#define ANS_NVMMU_TCB_INVAL	0x28118
+#define ANS_NVMMU_TCB_STAT	0x28120
+
+#define ANS_NVMMU_TCB_SIZE	0x4000
+#define ANS_NVMMU_TCB_PITCH	0x80
+
+/*
+ * The Apple NVMe controller includes an IOMMU known as NVMMU.  The
+ * NVMMU is programmed through an array of TCBs. These TCBs are paired
+ * with the corresponding slot in the submission queues and need to be
+ * configured with the command details before a command is allowed to
+ * execute. This is necessary even for commands that don't do DMA.
+ */
+struct ans_nvmmu_tcb {
+	u8 opcode;
+	u8 flags;
+	u8 slot;
+	u8 pad0;
+	u32 prpl_len;
+	u8 pad1[16];
+	u64 prp1;
+	u64 prp2;
+};
+
+#define ANS_NVMMU_TCB_WRITE	BIT(0)
+#define ANS_NVMMU_TCB_READ	BIT(1)
+
+struct apple_nvme_priv {
+	struct nvme_dev ndev;
+	void *base;		/* NVMe registers */
+	void *asc;		/* ASC registers */
+	struct reset_ctl_bulk resets; /* ASC reset */
+	struct mbox_chan chan;
+	struct ans_nvmmu_tcb *tcbs[NVME_Q_NUM]; /* Submission queue TCBs */
+	u32 __iomem *q_db[NVME_Q_NUM]; /* Submission queue doorbell */
+};
+
+static int apple_nvme_setup_queue(struct nvme_queue *nvmeq)
+{
+	struct apple_nvme_priv *priv =
+		container_of(nvmeq->dev, struct apple_nvme_priv, ndev);
+	struct nvme_dev *dev = nvmeq->dev;
+
+	switch (nvmeq->qid) {
+	case NVME_ADMIN_Q:
+	case NVME_IO_Q:
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	priv->tcbs[nvmeq->qid] = (void *)memalign(4096, ANS_NVMMU_TCB_SIZE);
+	memset((void *)priv->tcbs[nvmeq->qid], 0, ANS_NVMMU_TCB_SIZE);
+
+	switch (nvmeq->qid) {
+	case NVME_ADMIN_Q:
+		priv->q_db[nvmeq->qid] =
+			((void __iomem *)dev->bar) + ANS_ASQ_DB;
+		nvme_writeq((ulong)priv->tcbs[nvmeq->qid],
+			    ((void __iomem *)dev->bar) + ANS_NVMMU_BASE_ASQ);
+		break;
+	case NVME_IO_Q:
+		priv->q_db[nvmeq->qid] =
+			((void __iomem *)dev->bar) + ANS_IOSQ_DB;
+		nvme_writeq((ulong)priv->tcbs[nvmeq->qid],
+			    ((void __iomem *)dev->bar) + ANS_NVMMU_BASE_IOSQ);
+		break;
+	}
+
+	return 0;
+}
+
+static void apple_nvme_submit_cmd(struct nvme_queue *nvmeq,
+				  struct nvme_command *cmd)
+{
+	struct apple_nvme_priv *priv =
+		container_of(nvmeq->dev, struct apple_nvme_priv, ndev);
+	struct ans_nvmmu_tcb *tcb;
+	u16 tail = nvmeq->sq_tail;
+
+	tcb = ((void *)priv->tcbs[nvmeq->qid]) + tail * ANS_NVMMU_TCB_PITCH;
+	memset(tcb, 0, sizeof(*tcb));
+	tcb->opcode = cmd->common.opcode;
+	tcb->flags = ANS_NVMMU_TCB_WRITE | ANS_NVMMU_TCB_READ;
+	tcb->slot = tail;
+	tcb->prpl_len = cmd->rw.length;
+	tcb->prp1 = cmd->common.prp1;
+	tcb->prp2 = cmd->common.prp2;
+
+	writel(tail, priv->q_db[nvmeq->qid]);
+}
+
+static void apple_nvme_complete_cmd(struct nvme_queue *nvmeq,
+				    struct nvme_command *cmd)
+{
+	struct apple_nvme_priv *priv =
+		container_of(nvmeq->dev, struct apple_nvme_priv, ndev);
+	struct ans_nvmmu_tcb *tcb;
+	u16 tail = nvmeq->sq_tail;
+
+	tcb = ((void *)priv->tcbs[nvmeq->qid]) + tail * ANS_NVMMU_TCB_PITCH;
+	memset(tcb, 0, sizeof(*tcb));
+	writel(tail, ((void __iomem *)nvmeq->dev->bar) + ANS_NVMMU_TCB_INVAL);
+	readl(((void __iomem *)nvmeq->dev->bar) + ANS_NVMMU_TCB_STAT);
+
+	if (++tail == nvmeq->q_depth)
+		tail = 0;
+	nvmeq->sq_tail = tail;
+}
+
+static int apple_nvme_probe(struct udevice *dev)
+{
+	struct apple_nvme_priv *priv = dev_get_priv(dev);
+	fdt_addr_t addr;
+	u32 ctrl, stat;
+	int ret;
+
+	priv->base = dev_read_addr_ptr(dev);
+	if (!priv->base)
+		return -EINVAL;
+
+	addr = dev_read_addr_index(dev, 1);
+	if (addr == FDT_ADDR_T_NONE)
+		return -EINVAL;
+	priv->asc = map_sysmem(addr, 0);
+
+	ret = reset_get_bulk(dev, &priv->resets);
+	if (ret < 0)
+		return ret;
+
+	ret = mbox_get_by_index(dev, 0, &priv->chan);
+	if (ret < 0)
+		return ret;
+
+	ctrl = readl(priv->asc + REG_CPU_CTRL);
+	writel(ctrl | REG_CPU_CTRL_RUN, priv->asc + REG_CPU_CTRL);
+
+	ret = apple_rtkit_init(&priv->chan);
+	if (ret < 0)
+		return ret;
+
+	ret = readl_poll_sleep_timeout(priv->base + ANS_BOOT_STATUS, stat,
+				       (stat == ANS_BOOT_STATUS_OK), 100,
+				       500000);
+	if (ret < 0) {
+		printf("%s: NVMe firmware didn't boot\n", __func__);
+		return -ETIMEDOUT;
+	}
+
+	writel(ANS_LINEAR_SQ_CTRL_EN, priv->base + ANS_LINEAR_SQ_CTRL);
+	writel(((ANS_MAX_QUEUE_DEPTH << 16) | ANS_MAX_QUEUE_DEPTH),
+	       priv->base + ANS_MAX_PEND_CMDS_CTRL);
+
+	writel(readl(priv->base + ANS_UNKNOWN_CTRL) & ~ANS_PRP_NULL_CHECK,
+	       priv->base + ANS_UNKNOWN_CTRL);
+
+	strcpy(priv->ndev.vendor, "Apple");
+
+	writel((ANS_NVMMU_TCB_SIZE / ANS_NVMMU_TCB_PITCH) - 1,
+	       priv->base + ANS_NVMMU_NUM);
+	writel(0, priv->base + ANS_MODESEL);
+
+	priv->ndev.bar = priv->base;
+	return nvme_init(dev);
+}
+
+static int apple_nvme_remove(struct udevice *dev)
+{
+	struct apple_nvme_priv *priv = dev_get_priv(dev);
+	u32 ctrl;
+
+	nvme_shutdown(dev);
+
+	apple_rtkit_shutdown(&priv->chan, APPLE_RTKIT_PWR_STATE_SLEEP);
+
+	ctrl = readl(priv->asc + REG_CPU_CTRL);
+	writel(ctrl & ~REG_CPU_CTRL_RUN, priv->asc + REG_CPU_CTRL);
+
+	reset_assert_bulk(&priv->resets);
+	reset_deassert_bulk(&priv->resets);
+
+	return 0;
+}
+
+static const struct nvme_ops apple_nvme_ops = {
+	.setup_queue = apple_nvme_setup_queue,
+	.submit_cmd = apple_nvme_submit_cmd,
+	.complete_cmd = apple_nvme_complete_cmd,
+};
+
+static const struct udevice_id apple_nvme_ids[] = {
+	{ .compatible = "apple,nvme-ans2" },
+	{ /* sentinel */ }
+};
+
+U_BOOT_DRIVER(apple_nvme) = {
+	.name = "apple_nvme",
+	.id = UCLASS_NVME,
+	.of_match = apple_nvme_ids,
+	.priv_auto = sizeof(struct apple_nvme_priv),
+	.probe = apple_nvme_probe,
+	.remove = apple_nvme_remove,
+	.ops = &apple_nvme_ops,
+	.flags = DM_FLAG_OS_PREPARE,
+};