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https://github.com/AuxXxilium/linux_dsm_epyc7002.git
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b0209b3995
i915 has a hw i2c controller (gmbus) but for a bunch of stupid reasons we need to be able to fall back to the bit-banging algo on gpio pins. The current code sets up a 2nd i2c controller for the same i2c bus using the bit-banging algo. This has a bunch of issues, the major one being that userspace can directly access this fallback i2c adaptor behind the drivers back. But we need to frob a few registers before and after using fallback gpio bit-banging, so this horribly fails. The new plan is to only set up one i2c adaptor and transparently fall back to bit-banging by directly calling the xfer function of the bit- banging algo in the i2c core. To make that possible, export the 2 i2c algo functions. v2: As suggested by Jean Delvare, simply export the i2c_bit_algo vtable instead of the individual functions. Acked-by: Jean Delvare <khali@linux-fr.org> Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
55 lines
2.2 KiB
C
55 lines
2.2 KiB
C
/* ------------------------------------------------------------------------- */
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/* i2c-algo-bit.h i2c driver algorithms for bit-shift adapters */
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/* ------------------------------------------------------------------------- */
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/* Copyright (C) 1995-99 Simon G. Vogl
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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 as published by
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the Free Software Foundation; either version 2 of the License, or
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(at your option) any later version.
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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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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. */
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/* ------------------------------------------------------------------------- */
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/* With some changes from Kyösti Mälkki <kmalkki@cc.hut.fi> and even
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Frodo Looijaard <frodol@dds.nl> */
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#ifndef _LINUX_I2C_ALGO_BIT_H
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#define _LINUX_I2C_ALGO_BIT_H
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/* --- Defines for bit-adapters --------------------------------------- */
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/*
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* This struct contains the hw-dependent functions of bit-style adapters to
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* manipulate the line states, and to init any hw-specific features. This is
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* only used if you have more than one hw-type of adapter running.
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*/
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struct i2c_algo_bit_data {
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void *data; /* private data for lowlevel routines */
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void (*setsda) (void *data, int state);
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void (*setscl) (void *data, int state);
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int (*getsda) (void *data);
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int (*getscl) (void *data);
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int (*pre_xfer) (struct i2c_adapter *);
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void (*post_xfer) (struct i2c_adapter *);
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/* local settings */
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int udelay; /* half clock cycle time in us,
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minimum 2 us for fast-mode I2C,
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minimum 5 us for standard-mode I2C and SMBus,
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maximum 50 us for SMBus */
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int timeout; /* in jiffies */
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};
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int i2c_bit_add_bus(struct i2c_adapter *);
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int i2c_bit_add_numbered_bus(struct i2c_adapter *);
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extern const struct i2c_algorithm i2c_bit_algo;
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#endif /* _LINUX_I2C_ALGO_BIT_H */
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