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Diffstat (limited to 'include/linux/bif/driver.h')
| -rw-r--r-- | include/linux/bif/driver.h | 161 |
1 files changed, 161 insertions, 0 deletions
diff --git a/include/linux/bif/driver.h b/include/linux/bif/driver.h new file mode 100644 index 000000000000..184d46f72022 --- /dev/null +++ b/include/linux/bif/driver.h @@ -0,0 +1,161 @@ +/* Copyright (c) 2013, The Linux Foundation. All rights reserved. + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 and + * only version 2 as published by the Free Software Foundation. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + */ + +#ifndef _LINUX_BIF_DRIVER_H_ +#define _LINUX_BIF_DRIVER_H_ + +#include <linux/device.h> +#include <linux/err.h> +#include <linux/types.h> +#include <linux/bif/consumer.h> + +/** + * struct bif_ctrl_dev - opaque handle used to identify a given BIF controller + * device + */ +struct bif_ctrl_dev; + +/** + * struct bif_ctrl_ops - BIF operations which may be implemented by BIF + * controller drivers + * @bus_transaction: Perform the specified BIF transaction which does + * not result in any slave response. + * @bus_transaction_query: Perform the specified BIF transaction which + * expects a BQ response in the case of slave + * positive acknowledgement. + * @bus_transaction_read: Perform the specified BIF transaction which + * expects an RD or TACK response from the selected + * slave. + * @read_slave_registers: Perform all BIF transactions necessary to read + * the specified set of contiguous registers from + * the previously selected slave. This operation + * is used to optimize the common case of slave + * register reads since the a BIF controller driver + * can take advantage of BIF burst reads while the + * BIF core driver cannot due to the inherient + * tight timing requirements. + * @write_slave_registers: Perform all BIF transactions necessary to write + * the specified set of contiguous registers to + * the previously selected slave. This operation + * is used to optimize the common case of slave + * register writes since the a BIF controller + * driver can remove redundant steps when + * performing several WD commands in a row. + * @get_bus_period: Return the tau_bif BIF bus clock period in + * nanoseconds. + * @set_bus_period: Set the tau_bif BIF bus clock period in + * nanoseconds. If the exact period is not + * supported by the BIF controller hardware, then + * the next larger supported period should be used. + * @get_battery_presence: Return the current state of the battery pack. + * If a battery pack is present, then return >= 1. + * If a battery pack is not present, then return 0. + * If an error occurs during presence detection, + * then return errno. + * @get_battery_rid: Return the measured value of the Rid battery + * pack pull-down resistor in ohms. + * @get_bus_state: Return the current bus state as defined by one + * of the enum bif_bus_state values. + * @set_bus_state: Set the BIF bus state to the specified enum + * bif_bus_state value. + * + * The following operations must be defined by every BIF controller driver in + * order to ensure baseline functionality: + * bus_transaction, bus_transaction_query, get_bus_state, and set_bus_state. + * + * The BIF core driver is unaware of BIF transaction timing constraints. A + * given BIF controller driver must ensure that all timing constraints in the + * MIPI-BIF specification are met as transactions are carried out. + * + * Conversion between 11-bit and 17-bit BIF words (i.e. the insertion of BCF_n, + * parity bits, and the inversion bit) must be handled inside of the BIF + * controller driver (either in software or hardware). This guarantees maximum + * performance if hardware support is available. + * + * The bus_transaction_read operation must return -ETIMEDOUT in the case of no + * RD or TACK word received. This allows the transaction query, TQ, command + * to be used for slave selection verification. + * + * It is acceptable for the BIF bus state to be changed autonomously by a BIF + * controller driver in response to low level bus actions without a call to + * set_bus_state. One example is the case of receiving a slave interrupt + * while in interrupt state as this intrinsically causes the bus to enter the + * active communication state. + */ +struct bif_ctrl_ops { + int (*bus_transaction) (struct bif_ctrl_dev *bdev, int transaction, + u8 data); + int (*bus_transaction_query) (struct bif_ctrl_dev *bdev, + int transaction, u8 data, + bool *query_response); + int (*bus_transaction_read) (struct bif_ctrl_dev *bdev, + int transaction, u8 data, + int *response); + int (*read_slave_registers) (struct bif_ctrl_dev *bdev, u16 addr, + u8 *data, int len); + int (*write_slave_registers) (struct bif_ctrl_dev *bdev, u16 addr, + const u8 *data, int len); + int (*get_bus_period) (struct bif_ctrl_dev *bdev); + int (*set_bus_period) (struct bif_ctrl_dev *bdev, int period_ns); + int (*get_battery_presence) (struct bif_ctrl_dev *bdev); + int (*get_battery_rid) (struct bif_ctrl_dev *bdev); + int (*get_bus_state) (struct bif_ctrl_dev *bdev); + int (*set_bus_state) (struct bif_ctrl_dev *bdev, int state); +}; + +/** + * struct bif_ctrl_desc - BIF bus controller descriptor + * @name: Name used to identify the BIF controller + * @ops: BIF operations supported by the BIF controller + * @bus_clock_min_ns: Minimum tau_bif BIF bus clock period supported by the + * BIF controller + * @bus_clock_max_ns: Maximum tau_bif BIF bus clock period supported by the + * BIF controller + * + * Each BIF controller registered with the BIF core is described with a + * structure of this type. + */ +struct bif_ctrl_desc { + const char *name; + struct bif_ctrl_ops *ops; + int bus_clock_min_ns; + int bus_clock_max_ns; +}; + +#ifdef CONFIG_BIF + +struct bif_ctrl_dev *bif_ctrl_register(struct bif_ctrl_desc *bif_desc, + struct device *dev, void *driver_data, struct device_node *of_node); + +void bif_ctrl_unregister(struct bif_ctrl_dev *bdev); + +void *bdev_get_drvdata(struct bif_ctrl_dev *bdev); + +int bif_ctrl_notify_battery_changed(struct bif_ctrl_dev *bdev); +int bif_ctrl_notify_slave_irq(struct bif_ctrl_dev *bdev); + +#else + +static inline struct bif_ctrl_dev *bif_ctrl_register( + struct bif_ctrl_desc *bif_desc, struct device *dev, void *driver_data, + struct device_node *of_node) +{ return ERR_PTR(-EINVAL); } + +static inline void bif_ctrl_unregister(struct bif_ctrl_dev *bdev) { } + +static inline void *bdev_get_drvdata(struct bif_ctrl_dev *bdev) { return NULL; } + +int bif_ctrl_notify_slave_irq(struct bif_ctrl_dev *bdev) { return -EINVAL; } + +#endif + +#endif |