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/2018/7/9/987Signed-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.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/bus/Kconfig

@@ -201,5 +201,6 @@ config DA8XX_MSTPRI
 	  peripherals.
 
 source "drivers/bus/fsl-mc/Kconfig"
+source "drivers/bus/mhi/Kconfig"
 
 endmenu

drivers/bus/Makefile

@@ -34,3 +34,6 @@ obj-$(CONFIG_UNIPHIER_SYSTEM_BUS)	+= uniphier-system-bus.o
 obj-$(CONFIG_VEXPRESS_CONFIG)	+= vexpress-config.o
 
 obj-$(CONFIG_DA8XX_MSTPRI)	+= da8xx-mstpri.o
+
+# MHI
+obj-$(CONFIG_MHI_BUS)		+= mhi/

drivers/bus/mhi/Kconfig

+# 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.

drivers/bus/mhi/Makefile

+# core layer
+obj-y += core/

drivers/bus/mhi/core/Makefile

+obj-$(CONFIG_MHI_BUS) := mhi.o
+
+mhi-y := init.o

drivers/bus/mhi/core/internal.h

+/* 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 */

include/linux/mod_devicetable.h

@@ -821,4 +821,16 @@ struct wmi_device_id {
 	const void *context;
 };
 
+#define MHI_NAME_SIZE 32
+
+/**
+ * struct mhi_device_id - MHI device identification
+ * @chan: MHI channel name
+ * @driver_data: driver data;
+ */
+struct mhi_device_id {
+	const char chan[MHI_NAME_SIZE];
+	kernel_ulong_t driver_data;
+};
+
 #endif /* LINUX_MOD_DEVICETABLE_H */