162 lines
6.4 KiB
C
162 lines
6.4 KiB
C
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/* Copyright (c) 2013, The Linux Foundation. All rights reserved.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 and
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* only version 2 as published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*/
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#ifndef _LINUX_BIF_DRIVER_H_
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#define _LINUX_BIF_DRIVER_H_
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#include <linux/device.h>
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#include <linux/err.h>
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#include <linux/types.h>
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#include <linux/bif/consumer.h>
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/**
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* struct bif_ctrl_dev - opaque handle used to identify a given BIF controller
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* device
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*/
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struct bif_ctrl_dev;
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/**
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* struct bif_ctrl_ops - BIF operations which may be implemented by BIF
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* controller drivers
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* @bus_transaction: Perform the specified BIF transaction which does
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* not result in any slave response.
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* @bus_transaction_query: Perform the specified BIF transaction which
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* expects a BQ response in the case of slave
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* positive acknowledgement.
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* @bus_transaction_read: Perform the specified BIF transaction which
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* expects an RD or TACK response from the selected
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* slave.
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* @read_slave_registers: Perform all BIF transactions necessary to read
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* the specified set of contiguous registers from
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* the previously selected slave. This operation
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* is used to optimize the common case of slave
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* register reads since the a BIF controller driver
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* can take advantage of BIF burst reads while the
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* BIF core driver cannot due to the inherient
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* tight timing requirements.
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* @write_slave_registers: Perform all BIF transactions necessary to write
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* the specified set of contiguous registers to
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* the previously selected slave. This operation
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* is used to optimize the common case of slave
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* register writes since the a BIF controller
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* driver can remove redundant steps when
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* performing several WD commands in a row.
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* @get_bus_period: Return the tau_bif BIF bus clock period in
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* nanoseconds.
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* @set_bus_period: Set the tau_bif BIF bus clock period in
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* nanoseconds. If the exact period is not
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* supported by the BIF controller hardware, then
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* the next larger supported period should be used.
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* @get_battery_presence: Return the current state of the battery pack.
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* If a battery pack is present, then return >= 1.
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* If a battery pack is not present, then return 0.
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* If an error occurs during presence detection,
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* then return errno.
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* @get_battery_rid: Return the measured value of the Rid battery
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* pack pull-down resistor in ohms.
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* @get_bus_state: Return the current bus state as defined by one
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* of the enum bif_bus_state values.
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* @set_bus_state: Set the BIF bus state to the specified enum
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* bif_bus_state value.
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*
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* The following operations must be defined by every BIF controller driver in
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* order to ensure baseline functionality:
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* bus_transaction, bus_transaction_query, get_bus_state, and set_bus_state.
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*
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* The BIF core driver is unaware of BIF transaction timing constraints. A
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* given BIF controller driver must ensure that all timing constraints in the
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* MIPI-BIF specification are met as transactions are carried out.
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*
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* Conversion between 11-bit and 17-bit BIF words (i.e. the insertion of BCF_n,
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* parity bits, and the inversion bit) must be handled inside of the BIF
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* controller driver (either in software or hardware). This guarantees maximum
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* performance if hardware support is available.
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*
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* The bus_transaction_read operation must return -ETIMEDOUT in the case of no
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* RD or TACK word received. This allows the transaction query, TQ, command
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* to be used for slave selection verification.
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*
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* It is acceptable for the BIF bus state to be changed autonomously by a BIF
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* controller driver in response to low level bus actions without a call to
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* set_bus_state. One example is the case of receiving a slave interrupt
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* while in interrupt state as this intrinsically causes the bus to enter the
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* active communication state.
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*/
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struct bif_ctrl_ops {
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int (*bus_transaction) (struct bif_ctrl_dev *bdev, int transaction,
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u8 data);
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int (*bus_transaction_query) (struct bif_ctrl_dev *bdev,
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int transaction, u8 data,
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bool *query_response);
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int (*bus_transaction_read) (struct bif_ctrl_dev *bdev,
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int transaction, u8 data,
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int *response);
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int (*read_slave_registers) (struct bif_ctrl_dev *bdev, u16 addr,
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u8 *data, int len);
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int (*write_slave_registers) (struct bif_ctrl_dev *bdev, u16 addr,
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const u8 *data, int len);
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int (*get_bus_period) (struct bif_ctrl_dev *bdev);
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int (*set_bus_period) (struct bif_ctrl_dev *bdev, int period_ns);
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int (*get_battery_presence) (struct bif_ctrl_dev *bdev);
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int (*get_battery_rid) (struct bif_ctrl_dev *bdev);
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int (*get_bus_state) (struct bif_ctrl_dev *bdev);
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int (*set_bus_state) (struct bif_ctrl_dev *bdev, int state);
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};
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/**
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* struct bif_ctrl_desc - BIF bus controller descriptor
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* @name: Name used to identify the BIF controller
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* @ops: BIF operations supported by the BIF controller
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* @bus_clock_min_ns: Minimum tau_bif BIF bus clock period supported by the
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* BIF controller
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* @bus_clock_max_ns: Maximum tau_bif BIF bus clock period supported by the
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* BIF controller
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*
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* Each BIF controller registered with the BIF core is described with a
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* structure of this type.
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*/
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struct bif_ctrl_desc {
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const char *name;
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struct bif_ctrl_ops *ops;
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int bus_clock_min_ns;
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int bus_clock_max_ns;
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};
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#ifdef CONFIG_BIF
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struct bif_ctrl_dev *bif_ctrl_register(struct bif_ctrl_desc *bif_desc,
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struct device *dev, void *driver_data, struct device_node *of_node);
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void bif_ctrl_unregister(struct bif_ctrl_dev *bdev);
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void *bdev_get_drvdata(struct bif_ctrl_dev *bdev);
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int bif_ctrl_notify_battery_changed(struct bif_ctrl_dev *bdev);
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int bif_ctrl_notify_slave_irq(struct bif_ctrl_dev *bdev);
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#else
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static inline struct bif_ctrl_dev *bif_ctrl_register(
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struct bif_ctrl_desc *bif_desc, struct device *dev, void *driver_data,
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struct device_node *of_node)
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{ return ERR_PTR(-EINVAL); }
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static inline void bif_ctrl_unregister(struct bif_ctrl_dev *bdev) { }
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static inline void *bdev_get_drvdata(struct bif_ctrl_dev *bdev) { return NULL; }
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int bif_ctrl_notify_slave_irq(struct bif_ctrl_dev *bdev) { return -EINVAL; }
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#endif
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#endif
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