bus: mhi: core: Add support for registering MHI controllers

This commit adds support for registering MHI controller drivers with
the MHI stack. MHI controller drivers manages the interaction with the
MHI client devices such as the external modems and WiFi chipsets. They
are also the MHI bus master in charge of managing the physical link
between the host and client device.

This is based on the patch submitted by Sujeev Dias:
https://lkml.org/lkml/2018/7/9/987

Signed-off-by: Sujeev Dias <sdias@codeaurora.org>
Signed-off-by: Siddartha Mohanadoss <smohanad@codeaurora.org>
[jhugo: added static config for controllers and fixed several bugs]
Signed-off-by: Jeffrey Hugo <jhugo@codeaurora.org>
[mani: removed DT dependency, splitted and cleaned up for upstream]
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Link: https://lore.kernel.org/r/20200220095854.4804-3-manivannan.sadhasivam@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

5 files changed, 572 insertions, 0 deletions

diff --git a/drivers/bus/mhi/Kconfig b/drivers/bus/mhi/Kconfig
new file mode 100644
index 000000000000..a8bd9bd7db7c
--- /dev/null
+++ b/drivers/bus/mhi/Kconfig
@@ -0,0 +1,14 @@
+# SPDX-License-Identifier: GPL-2.0
+#
+# MHI bus
+#
+# Copyright (c) 2018-2020, The Linux Foundation. All rights reserved.
+#
+
+config MHI_BUS
+       tristate "Modem Host Interface (MHI) bus"
+       help
+	 Bus driver for MHI protocol. Modem Host Interface (MHI) is a
+	 communication protocol used by the host processors to control
+	 and communicate with modem devices over a high speed peripheral
+	 bus or shared memory.
diff --git a/drivers/bus/mhi/Makefile b/drivers/bus/mhi/Makefile
new file mode 100644
index 000000000000..19e6443b72df
--- /dev/null
+++ b/drivers/bus/mhi/Makefile
@@ -0,0 +1,2 @@
+# core layer
+obj-y += core/
diff --git a/drivers/bus/mhi/core/Makefile b/drivers/bus/mhi/core/Makefile
new file mode 100644
index 000000000000..2db32697c67f
--- /dev/null
+++ b/drivers/bus/mhi/core/Makefile
@@ -0,0 +1,3 @@
+obj-$(CONFIG_MHI_BUS) := mhi.o
+
+mhi-y := init.o
diff --git a/drivers/bus/mhi/core/init.c b/drivers/bus/mhi/core/init.c
new file mode 100644
index 000000000000..6f24c21284ec
--- /dev/null
+++ b/drivers/bus/mhi/core/init.c
@@ -0,0 +1,402 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2018-2020, The Linux Foundation. All rights reserved.
+ *
+ */
+
+#include <linux/device.h>
+#include <linux/dma-direction.h>
+#include <linux/dma-mapping.h>
+#include <linux/interrupt.h>
+#include <linux/list.h>
+#include <linux/mhi.h>
+#include <linux/mod_devicetable.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/vmalloc.h>
+#include <linux/wait.h>
+#include "internal.h"
+
+static int parse_ev_cfg(struct mhi_controller *mhi_cntrl,
+			struct mhi_controller_config *config)
+{
+	struct mhi_event *mhi_event;
+	struct mhi_event_config *event_cfg;
+	struct device *dev = &mhi_cntrl->mhi_dev->dev;
+	int i, num;
+
+	num = config->num_events;
+	mhi_cntrl->total_ev_rings = num;
+	mhi_cntrl->mhi_event = kcalloc(num, sizeof(*mhi_cntrl->mhi_event),
+				       GFP_KERNEL);
+	if (!mhi_cntrl->mhi_event)
+		return -ENOMEM;
+
+	/* Populate event ring */
+	mhi_event = mhi_cntrl->mhi_event;
+	for (i = 0; i < num; i++) {
+		event_cfg = &config->event_cfg[i];
+
+		mhi_event->er_index = i;
+		mhi_event->ring.elements = event_cfg->num_elements;
+		mhi_event->intmod = event_cfg->irq_moderation_ms;
+		mhi_event->irq = event_cfg->irq;
+
+		if (event_cfg->channel != U32_MAX) {
+			/* This event ring has a dedicated channel */
+			mhi_event->chan = event_cfg->channel;
+			if (mhi_event->chan >= mhi_cntrl->max_chan) {
+				dev_err(dev,
+					"Event Ring channel not available\n");
+				goto error_ev_cfg;
+			}
+
+			mhi_event->mhi_chan =
+				&mhi_cntrl->mhi_chan[mhi_event->chan];
+		}
+
+		/* Priority is fixed to 1 for now */
+		mhi_event->priority = 1;
+
+		mhi_event->db_cfg.brstmode = event_cfg->mode;
+		if (MHI_INVALID_BRSTMODE(mhi_event->db_cfg.brstmode))
+			goto error_ev_cfg;
+
+		mhi_event->data_type = event_cfg->data_type;
+
+		mhi_event->hw_ring = event_cfg->hardware_event;
+		if (mhi_event->hw_ring)
+			mhi_cntrl->hw_ev_rings++;
+		else
+			mhi_cntrl->sw_ev_rings++;
+
+		mhi_event->cl_manage = event_cfg->client_managed;
+		mhi_event->offload_ev = event_cfg->offload_channel;
+		mhi_event++;
+	}
+
+	/* We need IRQ for each event ring + additional one for BHI */
+	mhi_cntrl->nr_irqs_req = mhi_cntrl->total_ev_rings + 1;
+
+	return 0;
+
+error_ev_cfg:
+
+	kfree(mhi_cntrl->mhi_event);
+	return -EINVAL;
+}
+
+static int parse_ch_cfg(struct mhi_controller *mhi_cntrl,
+			struct mhi_controller_config *config)
+{
+	struct mhi_channel_config *ch_cfg;
+	struct device *dev = &mhi_cntrl->mhi_dev->dev;
+	int i;
+	u32 chan;
+
+	mhi_cntrl->max_chan = config->max_channels;
+
+	/*
+	 * The allocation of MHI channels can exceed 32KB in some scenarios,
+	 * so to avoid any memory possible allocation failures, vzalloc is
+	 * used here
+	 */
+	mhi_cntrl->mhi_chan = vzalloc(mhi_cntrl->max_chan *
+				      sizeof(*mhi_cntrl->mhi_chan));
+	if (!mhi_cntrl->mhi_chan)
+		return -ENOMEM;
+
+	INIT_LIST_HEAD(&mhi_cntrl->lpm_chans);
+
+	/* Populate channel configurations */
+	for (i = 0; i < config->num_channels; i++) {
+		struct mhi_chan *mhi_chan;
+
+		ch_cfg = &config->ch_cfg[i];
+
+		chan = ch_cfg->num;
+		if (chan >= mhi_cntrl->max_chan) {
+			dev_err(dev, "Channel %d not available\n", chan);
+			goto error_chan_cfg;
+		}
+
+		mhi_chan = &mhi_cntrl->mhi_chan[chan];
+		mhi_chan->name = ch_cfg->name;
+		mhi_chan->chan = chan;
+
+		mhi_chan->tre_ring.elements = ch_cfg->num_elements;
+		if (!mhi_chan->tre_ring.elements)
+			goto error_chan_cfg;
+
+		/*
+		 * For some channels, local ring length should be bigger than
+		 * the transfer ring length due to internal logical channels
+		 * in device. So host can queue much more buffers than transfer
+		 * ring length. Example, RSC channels should have a larger local
+		 * channel length than transfer ring length.
+		 */
+		mhi_chan->buf_ring.elements = ch_cfg->local_elements;
+		if (!mhi_chan->buf_ring.elements)
+			mhi_chan->buf_ring.elements = mhi_chan->tre_ring.elements;
+		mhi_chan->er_index = ch_cfg->event_ring;
+		mhi_chan->dir = ch_cfg->dir;
+
+		/*
+		 * For most channels, chtype is identical to channel directions.
+		 * So, if it is not defined then assign channel direction to
+		 * chtype
+		 */
+		mhi_chan->type = ch_cfg->type;
+		if (!mhi_chan->type)
+			mhi_chan->type = (enum mhi_ch_type)mhi_chan->dir;
+
+		mhi_chan->ee_mask = ch_cfg->ee_mask;
+		mhi_chan->db_cfg.pollcfg = ch_cfg->pollcfg;
+		mhi_chan->lpm_notify = ch_cfg->lpm_notify;
+		mhi_chan->offload_ch = ch_cfg->offload_channel;
+		mhi_chan->db_cfg.reset_req = ch_cfg->doorbell_mode_switch;
+		mhi_chan->pre_alloc = ch_cfg->auto_queue;
+		mhi_chan->auto_start = ch_cfg->auto_start;
+
+		/*
+		 * If MHI host allocates buffers, then the channel direction
+		 * should be DMA_FROM_DEVICE
+		 */
+		if (mhi_chan->pre_alloc && mhi_chan->dir != DMA_FROM_DEVICE) {
+			dev_err(dev, "Invalid channel configuration\n");
+			goto error_chan_cfg;
+		}
+
+		/*
+		 * Bi-directional and direction less channel must be an
+		 * offload channel
+		 */
+		if ((mhi_chan->dir == DMA_BIDIRECTIONAL ||
+		     mhi_chan->dir == DMA_NONE) && !mhi_chan->offload_ch) {
+			dev_err(dev, "Invalid channel configuration\n");
+			goto error_chan_cfg;
+		}
+
+		if (!mhi_chan->offload_ch) {
+			mhi_chan->db_cfg.brstmode = ch_cfg->doorbell;
+			if (MHI_INVALID_BRSTMODE(mhi_chan->db_cfg.brstmode)) {
+				dev_err(dev, "Invalid Door bell mode\n");
+				goto error_chan_cfg;
+			}
+		}
+
+		mhi_chan->configured = true;
+
+		if (mhi_chan->lpm_notify)
+			list_add_tail(&mhi_chan->node, &mhi_cntrl->lpm_chans);
+	}
+
+	return 0;
+
+error_chan_cfg:
+	vfree(mhi_cntrl->mhi_chan);
+
+	return -EINVAL;
+}
+
+static int parse_config(struct mhi_controller *mhi_cntrl,
+			struct mhi_controller_config *config)
+{
+	int ret;
+
+	/* Parse MHI channel configuration */
+	ret = parse_ch_cfg(mhi_cntrl, config);
+	if (ret)
+		return ret;
+
+	/* Parse MHI event configuration */
+	ret = parse_ev_cfg(mhi_cntrl, config);
+	if (ret)
+		goto error_ev_cfg;
+
+	mhi_cntrl->timeout_ms = config->timeout_ms;
+	if (!mhi_cntrl->timeout_ms)
+		mhi_cntrl->timeout_ms = MHI_TIMEOUT_MS;
+
+	mhi_cntrl->bounce_buf = config->use_bounce_buf;
+	mhi_cntrl->buffer_len = config->buf_len;
+	if (!mhi_cntrl->buffer_len)
+		mhi_cntrl->buffer_len = MHI_MAX_MTU;
+
+	return 0;
+
+error_ev_cfg:
+	vfree(mhi_cntrl->mhi_chan);
+
+	return ret;
+}
+
+int mhi_register_controller(struct mhi_controller *mhi_cntrl,
+			    struct mhi_controller_config *config)
+{
+	int ret;
+	int i;
+	struct mhi_event *mhi_event;
+	struct mhi_chan *mhi_chan;
+	struct mhi_cmd *mhi_cmd;
+	struct mhi_device *mhi_dev;
+
+	if (!mhi_cntrl)
+		return -EINVAL;
+
+	if (!mhi_cntrl->runtime_get || !mhi_cntrl->runtime_put)
+		return -EINVAL;
+
+	if (!mhi_cntrl->status_cb || !mhi_cntrl->link_status)
+		return -EINVAL;
+
+	ret = parse_config(mhi_cntrl, config);
+	if (ret)
+		return -EINVAL;
+
+	mhi_cntrl->mhi_cmd = kcalloc(NR_OF_CMD_RINGS,
+				     sizeof(*mhi_cntrl->mhi_cmd), GFP_KERNEL);
+	if (!mhi_cntrl->mhi_cmd) {
+		ret = -ENOMEM;
+		goto error_alloc_cmd;
+	}
+
+	INIT_LIST_HEAD(&mhi_cntrl->transition_list);
+	spin_lock_init(&mhi_cntrl->transition_lock);
+	spin_lock_init(&mhi_cntrl->wlock);
+	init_waitqueue_head(&mhi_cntrl->state_event);
+
+	mhi_cmd = mhi_cntrl->mhi_cmd;
+	for (i = 0; i < NR_OF_CMD_RINGS; i++, mhi_cmd++)
+		spin_lock_init(&mhi_cmd->lock);
+
+	mhi_event = mhi_cntrl->mhi_event;
+	for (i = 0; i < mhi_cntrl->total_ev_rings; i++, mhi_event++) {
+		/* Skip for offload events */
+		if (mhi_event->offload_ev)
+			continue;
+
+		mhi_event->mhi_cntrl = mhi_cntrl;
+		spin_lock_init(&mhi_event->lock);
+	}
+
+	mhi_chan = mhi_cntrl->mhi_chan;
+	for (i = 0; i < mhi_cntrl->max_chan; i++, mhi_chan++) {
+		mutex_init(&mhi_chan->mutex);
+		init_completion(&mhi_chan->completion);
+		rwlock_init(&mhi_chan->lock);
+	}
+
+	/* Register controller with MHI bus */
+	mhi_dev = mhi_alloc_device(mhi_cntrl);
+	if (IS_ERR(mhi_dev)) {
+		dev_err(mhi_cntrl->cntrl_dev, "Failed to allocate MHI device\n");
+		ret = PTR_ERR(mhi_dev);
+		goto error_alloc_dev;
+	}
+
+	mhi_dev->dev_type = MHI_DEVICE_CONTROLLER;
+	mhi_dev->mhi_cntrl = mhi_cntrl;
+	dev_set_name(&mhi_dev->dev, "%s", dev_name(mhi_cntrl->cntrl_dev));
+
+	/* Init wakeup source */
+	device_init_wakeup(&mhi_dev->dev, true);
+
+	ret = device_add(&mhi_dev->dev);
+	if (ret)
+		goto error_add_dev;
+
+	mhi_cntrl->mhi_dev = mhi_dev;
+
+	return 0;
+
+error_add_dev:
+	put_device(&mhi_dev->dev);
+
+error_alloc_dev:
+	kfree(mhi_cntrl->mhi_cmd);
+
+error_alloc_cmd:
+	vfree(mhi_cntrl->mhi_chan);
+	kfree(mhi_cntrl->mhi_event);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(mhi_register_controller);
+
+void mhi_unregister_controller(struct mhi_controller *mhi_cntrl)
+{
+	struct mhi_device *mhi_dev = mhi_cntrl->mhi_dev;
+	struct mhi_chan *mhi_chan = mhi_cntrl->mhi_chan;
+	unsigned int i;
+
+	kfree(mhi_cntrl->mhi_cmd);
+	kfree(mhi_cntrl->mhi_event);
+
+	/* Drop the references to MHI devices created for channels */
+	for (i = 0; i < mhi_cntrl->max_chan; i++, mhi_chan++) {
+		if (!mhi_chan->mhi_dev)
+			continue;
+
+		put_device(&mhi_chan->mhi_dev->dev);
+	}
+	vfree(mhi_cntrl->mhi_chan);
+
+	device_del(&mhi_dev->dev);
+	put_device(&mhi_dev->dev);
+}
+EXPORT_SYMBOL_GPL(mhi_unregister_controller);
+
+static void mhi_release_device(struct device *dev)
+{
+	struct mhi_device *mhi_dev = to_mhi_device(dev);
+
+	kfree(mhi_dev);
+}
+
+struct mhi_device *mhi_alloc_device(struct mhi_controller *mhi_cntrl)
+{
+	struct mhi_device *mhi_dev;
+	struct device *dev;
+
+	mhi_dev = kzalloc(sizeof(*mhi_dev), GFP_KERNEL);
+	if (!mhi_dev)
+		return ERR_PTR(-ENOMEM);
+
+	dev = &mhi_dev->dev;
+	device_initialize(dev);
+	dev->bus = &mhi_bus_type;
+	dev->release = mhi_release_device;
+	dev->parent = mhi_cntrl->cntrl_dev;
+	mhi_dev->mhi_cntrl = mhi_cntrl;
+	mhi_dev->dev_wake = 0;
+
+	return mhi_dev;
+}
+
+static int mhi_match(struct device *dev, struct device_driver *drv)
+{
+	return 0;
+};
+
+struct bus_type mhi_bus_type = {
+	.name = "mhi",
+	.dev_name = "mhi",
+	.match = mhi_match,
+};
+
+static int __init mhi_init(void)
+{
+	return bus_register(&mhi_bus_type);
+}
+
+static void __exit mhi_exit(void)
+{
+	bus_unregister(&mhi_bus_type);
+}
+
+postcore_initcall(mhi_init);
+module_exit(mhi_exit);
+
+MODULE_LICENSE("GPL v2");
+MODULE_DESCRIPTION("MHI Host Interface");
diff --git a/drivers/bus/mhi/core/internal.h b/drivers/bus/mhi/core/internal.h
new file mode 100644
index 000000000000..6af59ac3ec9d
--- /dev/null
+++ b/drivers/bus/mhi/core/internal.h
@@ -0,0 +1,151 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (c) 2018-2020, The Linux Foundation. All rights reserved.
+ *
+ */
+
+#ifndef _MHI_INT_H
+#define _MHI_INT_H
+
+#include <linux/mhi.h>
+
+extern struct bus_type mhi_bus_type;
+
+/* MHI transfer completion events */
+enum mhi_ev_ccs {
+	MHI_EV_CC_INVALID = 0x0,
+	MHI_EV_CC_SUCCESS = 0x1,
+	MHI_EV_CC_EOT = 0x2, /* End of transfer event */
+	MHI_EV_CC_OVERFLOW = 0x3,
+	MHI_EV_CC_EOB = 0x4, /* End of block event */
+	MHI_EV_CC_OOB = 0x5, /* Out of block event */
+	MHI_EV_CC_DB_MODE = 0x6,
+	MHI_EV_CC_UNDEFINED_ERR = 0x10,
+	MHI_EV_CC_BAD_TRE = 0x11,
+};
+
+enum mhi_ch_state {
+	MHI_CH_STATE_DISABLED = 0x0,
+	MHI_CH_STATE_ENABLED = 0x1,
+	MHI_CH_STATE_RUNNING = 0x2,
+	MHI_CH_STATE_SUSPENDED = 0x3,
+	MHI_CH_STATE_STOP = 0x4,
+	MHI_CH_STATE_ERROR = 0x5,
+};
+
+#define MHI_INVALID_BRSTMODE(mode) (mode != MHI_DB_BRST_DISABLE && \
+				    mode != MHI_DB_BRST_ENABLE)
+
+#define NR_OF_CMD_RINGS			1
+#define CMD_EL_PER_RING			128
+#define PRIMARY_CMD_RING		0
+#define MHI_MAX_MTU			0xffff
+
+enum mhi_er_type {
+	MHI_ER_TYPE_INVALID = 0x0,
+	MHI_ER_TYPE_VALID = 0x1,
+};
+
+struct db_cfg {
+	bool reset_req;
+	bool db_mode;
+	u32 pollcfg;
+	enum mhi_db_brst_mode brstmode;
+	dma_addr_t db_val;
+	void (*process_db)(struct mhi_controller *mhi_cntrl,
+			   struct db_cfg *db_cfg, void __iomem *io_addr,
+			   dma_addr_t db_val);
+};
+
+struct mhi_ring {
+	dma_addr_t dma_handle;
+	dma_addr_t iommu_base;
+	u64 *ctxt_wp; /* point to ctxt wp */
+	void *pre_aligned;
+	void *base;
+	void *rp;
+	void *wp;
+	size_t el_size;
+	size_t len;
+	size_t elements;
+	size_t alloc_size;
+	void __iomem *db_addr;
+};
+
+struct mhi_cmd {
+	struct mhi_ring ring;
+	spinlock_t lock;
+};
+
+struct mhi_buf_info {
+	void *v_addr;
+	void *bb_addr;
+	void *wp;
+	void *cb_buf;
+	dma_addr_t p_addr;
+	size_t len;
+	enum dma_data_direction dir;
+};
+
+struct mhi_event {
+	struct mhi_controller *mhi_cntrl;
+	struct mhi_chan *mhi_chan; /* dedicated to channel */
+	u32 er_index;
+	u32 intmod;
+	u32 irq;
+	int chan; /* this event ring is dedicated to a channel (optional) */
+	u32 priority;
+	enum mhi_er_data_type data_type;
+	struct mhi_ring ring;
+	struct db_cfg db_cfg;
+	struct tasklet_struct task;
+	spinlock_t lock;
+	int (*process_event)(struct mhi_controller *mhi_cntrl,
+			     struct mhi_event *mhi_event,
+			     u32 event_quota);
+	bool hw_ring;
+	bool cl_manage;
+	bool offload_ev; /* managed by a device driver */
+};
+
+struct mhi_chan {
+	const char *name;
+	/*
+	 * Important: When consuming, increment tre_ring first and when
+	 * releasing, decrement buf_ring first. If tre_ring has space, buf_ring
+	 * is guranteed to have space so we do not need to check both rings.
+	 */
+	struct mhi_ring buf_ring;
+	struct mhi_ring tre_ring;
+	u32 chan;
+	u32 er_index;
+	u32 intmod;
+	enum mhi_ch_type type;
+	enum dma_data_direction dir;
+	struct db_cfg db_cfg;
+	enum mhi_ch_ee_mask ee_mask;
+	enum mhi_ch_state ch_state;
+	enum mhi_ev_ccs ccs;
+	struct mhi_device *mhi_dev;
+	void (*xfer_cb)(struct mhi_device *mhi_dev, struct mhi_result *result);
+	struct mutex mutex;
+	struct completion completion;
+	rwlock_t lock;
+	struct list_head node;
+	bool lpm_notify;
+	bool configured;
+	bool offload_ch;
+	bool pre_alloc;
+	bool auto_start;
+	bool wake_capable;
+};
+
+/* Default MHI timeout */
+#define MHI_TIMEOUT_MS (1000)
+
+struct mhi_device *mhi_alloc_device(struct mhi_controller *mhi_cntrl);
+
+int mhi_destroy_device(struct device *dev, void *data);
+void mhi_create_devices(struct mhi_controller *mhi_cntrl);
+
+#endif /* _MHI_INT_H */