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Reinvent I2C ops

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Do not use the global platform_i2c_transfer() function that can only be
implemented by a single driver. Instead, make a `struct device` aware
transfer() function the only interface function for I2C controller dri-
vers to implement.

To not force the slave device drivers to be implemented either above
generic I2C or specialized SMBus operations, we support SMBus control-
lers in the slave device interface too.

We start with four simple slave functions: i2c_readb(), i2c_writeb(),
i2c_readb_at() and i2c_writeb_at(). They are all compatible to respec-
tive SMBus functions. But we keep aliases because it would be weird to
force e.g. an I2C EEPROM driver to call smbus_read_byte().

Change-Id: I98386f91bf4799ba3df84ec8bc0f64edd4142818
Signed-off-by: Nico Huber <nico.huber@secunet.com>
Reviewed-on: https://review.coreboot.org/20846
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
This commit is contained in:
Nico Huber
2017-08-01 17:09:35 +02:00
committed by Martin Roth
parent 0f2dd1eff9
commit 581738642f
9 changed files with 267 additions and 112 deletions
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82
src/include/device/i2c_bus.h
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@@ -1,8 +1,6 @@
/*
* This file is part of the coreboot project.
*
* Copyright (C) 2014 Google, Inc.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; version 2 of the License.
@@ -16,29 +14,79 @@
#ifndef _DEVICE_I2C_BUS_H_
#define _DEVICE_I2C_BUS_H_
#include <stdlib.h>
#include <stdint.h>
#include <device/i2c.h>
#include <device/device.h>
/* I2C bus operation for ramstage drivers */
struct i2c_bus_operations {
/*
* This is an SOC specific method that can be provided to translate the
* 'struct device' for an I2C controller into a unique I2C bus number.
* Returns -1 if the bus number for this device cannot be determined.
*/
int (*dev_to_bus)(struct device *dev);
int (*transfer)(struct device *, const struct i2c_msg *, size_t count);
};
/* Return I2C bus number for provided device, -1 if not found */
int i2c_dev_find_bus(struct device *dev);
/*
* Returns the first upstream facing link whose bus implements either
* `i2c_bus_operations` *or* `smbus_bus_operations`.
*
* If not NULL, guarantees that `->dev`, `->dev->ops` and either
* `->dev->ops->ops_i2c_bus` or `->dev->ops->ops_smbus_bus` are
* not NULL.
*/
struct bus *i2c_link(struct device *);
/* Variants of I2C helper functions that take a device instead of bus number */
int i2c_dev_transfer(struct device *dev, struct i2c_msg *segments, int count);
int i2c_dev_readb(struct device *dev, uint8_t reg, uint8_t *data);
int i2c_dev_writeb(struct device *dev, uint8_t reg, uint8_t data);
int i2c_dev_read_bytes(struct device *dev, uint8_t reg, uint8_t *data, int len);
int i2c_dev_read_raw(struct device *dev, uint8_t *data, int len);
int i2c_dev_write_raw(struct device *dev, uint8_t *data, int len);
/*
* Shorthand for `i2c_link(dev)->dev`.
*
* Returns NULL if i2c_link(dev) returns NULL.
*/
static inline struct device *i2c_busdev(struct device *dev)
{
struct bus *const link = i2c_link(dev);
return link ? link->dev : NULL;
}
/*
* Slave driver interface functions. These will look for the next
* `i2c_bus_operations` *or* `smbus_bus_operations` and perform the
* respective transfers.
*
* The interface is limited to what current slave drivers demand.
* Extend as required.
*
* All functions return a negative `enum cb_err` value on error.
* Either CB_ERR, CB_ERR_ARG or any CB_I2C_* (cf. include/types.h).
*/
/*
* Reads one byte.
* Compatible to smbus_recv_byte().
*
* Returns the read byte on success, negative `enum cb_err` value on error.
*/
int i2c_readb(struct device *);
/*
* Writes the byte `val`.
* Compatible to smbus_send_byte().
*
* Returns 0 on success, negative `enum cb_err` value on error.
*/
int i2c_writeb(struct device *, uint8_t val);
/*
* Sends the register offset `off` and reads one byte.
* Compatible to smbus_read_byte().
*
* Returns the read byte on success, negative `enum cb_err` value on error.
*/
int i2c_readb_at(struct device *, uint8_t off);
/*
* Sends the register offset `off` followed by the byte `val`.
* Compatible to smbus_write_byte().
*
* Returns 0 on success, negative `enum cb_err` value on error.
*/
int i2c_writeb_at(struct device *, uint8_t off, uint8_t val);
#endif /* _DEVICE_I2C_BUS_H_ */

10
src/include/device/smbus_def.h
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@@ -1,10 +1,12 @@
#ifndef DEVICE_SMBUS_DEF_H
#define DEVICE_SMBUS_DEF_H
#include <types.h>
/* Error results are negative success is >= 0 */
#define SMBUS_ERROR -1
#define SMBUS_WAIT_UNTIL_READY_TIMEOUT -2
#define SMBUS_WAIT_UNTIL_DONE_TIMEOUT -3
#define SMBUS_WAIT_UNTIL_ACTIVE_TIMEOUT -4
#define SMBUS_ERROR CB_ERR
#define SMBUS_WAIT_UNTIL_READY_TIMEOUT CB_I2C_BUSY
#define SMBUS_WAIT_UNTIL_DONE_TIMEOUT CB_I2C_TIMEOUT
#define SMBUS_WAIT_UNTIL_ACTIVE_TIMEOUT CB_I2C_NO_DEVICE
#endif /* DEVICE_SMBUS_DEF_H */

9
src/include/types.h
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@@ -47,7 +47,14 @@ enum cb_err {
/* Keyboard test failures */
CB_KBD_CONTROLLER_FAILURE = -200,
CB_KBD_INTERFACE_FAILURE = -201
CB_KBD_INTERFACE_FAILURE = -201,
/* I2C controller failures */
CB_I2C_NO_DEVICE = -300, /**< Device is not responding */
CB_I2C_BUSY = -301, /**< Device tells it's busy */
CB_I2C_PROTOCOL_ERROR = -302, /**< Data lost or spurious slave
device response, try again? */
CB_I2C_TIMEOUT = -303, /**< Transmission timed out */
};
#endif /* __TYPES_H */