cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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intel_i2c.c (3737B)

      1// SPDX-License-Identifier: GPL-2.0-only
      2/*
      3 * Copyright © 2006-2007 Intel Corporation
      4 *
      5 * Authors:
      6 *	Eric Anholt <eric@anholt.net>
      7 */
      8
      9#include <linux/delay.h>
     10#include <linux/export.h>
     11#include <linux/i2c-algo-bit.h>
     12#include <linux/i2c.h>
     13
     14#include "psb_drv.h"
     15#include "psb_intel_reg.h"
     16
     17/*
     18 * Intel GPIO access functions
     19 */
     20
     21#define I2C_RISEFALL_TIME 20
     22
     23static int get_clock(void *data)
     24{
     25	struct psb_intel_i2c_chan *chan = data;
     26	struct drm_device *dev = chan->drm_dev;
     27	u32 val;
     28
     29	val = REG_READ(chan->reg);
     30	return (val & GPIO_CLOCK_VAL_IN) != 0;
     31}
     32
     33static int get_data(void *data)
     34{
     35	struct psb_intel_i2c_chan *chan = data;
     36	struct drm_device *dev = chan->drm_dev;
     37	u32 val;
     38
     39	val = REG_READ(chan->reg);
     40	return (val & GPIO_DATA_VAL_IN) != 0;
     41}
     42
     43static void set_clock(void *data, int state_high)
     44{
     45	struct psb_intel_i2c_chan *chan = data;
     46	struct drm_device *dev = chan->drm_dev;
     47	u32 reserved = 0, clock_bits;
     48
     49	/* On most chips, these bits must be preserved in software. */
     50	reserved =
     51		    REG_READ(chan->reg) & (GPIO_DATA_PULLUP_DISABLE |
     52					   GPIO_CLOCK_PULLUP_DISABLE);
     53
     54	if (state_high)
     55		clock_bits = GPIO_CLOCK_DIR_IN | GPIO_CLOCK_DIR_MASK;
     56	else
     57		clock_bits = GPIO_CLOCK_DIR_OUT | GPIO_CLOCK_DIR_MASK |
     58		    GPIO_CLOCK_VAL_MASK;
     59	REG_WRITE(chan->reg, reserved | clock_bits);
     60	udelay(I2C_RISEFALL_TIME);	/* wait for the line to change state */
     61}
     62
     63static void set_data(void *data, int state_high)
     64{
     65	struct psb_intel_i2c_chan *chan = data;
     66	struct drm_device *dev = chan->drm_dev;
     67	u32 reserved = 0, data_bits;
     68
     69	/* On most chips, these bits must be preserved in software. */
     70	reserved =
     71		    REG_READ(chan->reg) & (GPIO_DATA_PULLUP_DISABLE |
     72					   GPIO_CLOCK_PULLUP_DISABLE);
     73
     74	if (state_high)
     75		data_bits = GPIO_DATA_DIR_IN | GPIO_DATA_DIR_MASK;
     76	else
     77		data_bits =
     78		    GPIO_DATA_DIR_OUT | GPIO_DATA_DIR_MASK |
     79		    GPIO_DATA_VAL_MASK;
     80
     81	REG_WRITE(chan->reg, reserved | data_bits);
     82	udelay(I2C_RISEFALL_TIME);	/* wait for the line to change state */
     83}
     84
     85/**
     86 * psb_intel_i2c_create - instantiate an Intel i2c bus using the specified GPIO reg
     87 * @dev: DRM device
     88 * @reg: GPIO reg to use
     89 * @name: name for this bus
     90 *
     91 * Creates and registers a new i2c bus with the Linux i2c layer, for use
     92 * in output probing and control (e.g. DDC or SDVO control functions).
     93 *
     94 * Possible values for @reg include:
     95 *   %GPIOA
     96 *   %GPIOB
     97 *   %GPIOC
     98 *   %GPIOD
     99 *   %GPIOE
    100 *   %GPIOF
    101 *   %GPIOG
    102 *   %GPIOH
    103 * see PRM for details on how these different busses are used.
    104 */
    105struct psb_intel_i2c_chan *psb_intel_i2c_create(struct drm_device *dev,
    106					const u32 reg, const char *name)
    107{
    108	struct psb_intel_i2c_chan *chan;
    109
    110	chan = kzalloc(sizeof(struct psb_intel_i2c_chan), GFP_KERNEL);
    111	if (!chan)
    112		goto out_free;
    113
    114	chan->drm_dev = dev;
    115	chan->reg = reg;
    116	snprintf(chan->adapter.name, I2C_NAME_SIZE, "intel drm %s", name);
    117	chan->adapter.owner = THIS_MODULE;
    118	chan->adapter.algo_data = &chan->algo;
    119	chan->adapter.dev.parent = dev->dev;
    120	chan->algo.setsda = set_data;
    121	chan->algo.setscl = set_clock;
    122	chan->algo.getsda = get_data;
    123	chan->algo.getscl = get_clock;
    124	chan->algo.udelay = 20;
    125	chan->algo.timeout = usecs_to_jiffies(2200);
    126	chan->algo.data = chan;
    127
    128	i2c_set_adapdata(&chan->adapter, chan);
    129
    130	if (i2c_bit_add_bus(&chan->adapter))
    131		goto out_free;
    132
    133	/* JJJ:  raise SCL and SDA? */
    134	set_data(chan, 1);
    135	set_clock(chan, 1);
    136	udelay(20);
    137
    138	return chan;
    139
    140out_free:
    141	kfree(chan);
    142	return NULL;
    143}
    144
    145/**
    146 * psb_intel_i2c_destroy - unregister and free i2c bus resources
    147 * @chan: channel to free
    148 *
    149 * Unregister the adapter from the i2c layer, then free the structure.
    150 */
    151void psb_intel_i2c_destroy(struct psb_intel_i2c_chan *chan)
    152{
    153	if (!chan)
    154		return;
    155
    156	i2c_del_adapter(&chan->adapter);
    157	kfree(chan);
    158}