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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w1_ds2413.c (4172B)

      1// SPDX-License-Identifier: GPL-2.0-only
      2/*
      3 * w1_ds2413.c - w1 family 3a (DS2413) driver
      4 * based on w1_ds2408.c by Jean-Francois Dagenais <dagenaisj@sonatest.com>
      5 *
      6 * Copyright (c) 2013 Mariusz Bialonczyk <manio@skyboo.net>
      7 */
      8
      9#include <linux/kernel.h>
     10#include <linux/module.h>
     11#include <linux/moduleparam.h>
     12#include <linux/device.h>
     13#include <linux/types.h>
     14#include <linux/delay.h>
     15#include <linux/slab.h>
     16
     17#include <linux/w1.h>
     18
     19#define W1_FAMILY_DS2413	0x3A
     20
     21#define W1_F3A_RETRIES                     3
     22#define W1_F3A_FUNC_PIO_ACCESS_READ        0xF5
     23#define W1_F3A_FUNC_PIO_ACCESS_WRITE       0x5A
     24#define W1_F3A_SUCCESS_CONFIRM_BYTE        0xAA
     25#define W1_F3A_INVALID_PIO_STATE           0xFF
     26
     27static ssize_t state_read(struct file *filp, struct kobject *kobj,
     28			  struct bin_attribute *bin_attr, char *buf, loff_t off,
     29			  size_t count)
     30{
     31	struct w1_slave *sl = kobj_to_w1_slave(kobj);
     32	unsigned int retries = W1_F3A_RETRIES;
     33	ssize_t bytes_read = -EIO;
     34	u8 state;
     35
     36	dev_dbg(&sl->dev,
     37		"Reading %s kobj: %p, off: %0#10x, count: %zu, buff addr: %p",
     38		bin_attr->attr.name, kobj, (unsigned int)off, count, buf);
     39
     40	if (off != 0)
     41		return 0;
     42	if (!buf)
     43		return -EINVAL;
     44
     45	mutex_lock(&sl->master->bus_mutex);
     46	dev_dbg(&sl->dev, "mutex locked");
     47
     48next:
     49	if (w1_reset_select_slave(sl))
     50		goto out;
     51
     52	while (retries--) {
     53		w1_write_8(sl->master, W1_F3A_FUNC_PIO_ACCESS_READ);
     54
     55		state = w1_read_8(sl->master);
     56		if ((state & 0x0F) == ((~state >> 4) & 0x0F)) {
     57			/* complement is correct */
     58			*buf = state;
     59			bytes_read = 1;
     60			goto out;
     61		} else if (state == W1_F3A_INVALID_PIO_STATE) {
     62			/* slave didn't respond, try to select it again */
     63			dev_warn(&sl->dev, "slave device did not respond to PIO_ACCESS_READ, " \
     64					    "reselecting, retries left: %d\n", retries);
     65			goto next;
     66		}
     67
     68		if (w1_reset_resume_command(sl->master))
     69			goto out; /* unrecoverable error */
     70
     71		dev_warn(&sl->dev, "PIO_ACCESS_READ error, retries left: %d\n", retries);
     72	}
     73
     74out:
     75	mutex_unlock(&sl->master->bus_mutex);
     76	dev_dbg(&sl->dev, "%s, mutex unlocked, retries: %d\n",
     77		(bytes_read > 0) ? "succeeded" : "error", retries);
     78	return bytes_read;
     79}
     80
     81static BIN_ATTR_RO(state, 1);
     82
     83static ssize_t output_write(struct file *filp, struct kobject *kobj,
     84			    struct bin_attribute *bin_attr, char *buf,
     85			    loff_t off, size_t count)
     86{
     87	struct w1_slave *sl = kobj_to_w1_slave(kobj);
     88	u8 w1_buf[3];
     89	unsigned int retries = W1_F3A_RETRIES;
     90	ssize_t bytes_written = -EIO;
     91
     92	if (count != 1 || off != 0)
     93		return -EFAULT;
     94
     95	dev_dbg(&sl->dev, "locking mutex for write_output");
     96	mutex_lock(&sl->master->bus_mutex);
     97	dev_dbg(&sl->dev, "mutex locked");
     98
     99	if (w1_reset_select_slave(sl))
    100		goto out;
    101
    102	/* according to the DS2413 datasheet the most significant 6 bits
    103	   should be set to "1"s, so do it now */
    104	*buf = *buf | 0xFC;
    105
    106	while (retries--) {
    107		w1_buf[0] = W1_F3A_FUNC_PIO_ACCESS_WRITE;
    108		w1_buf[1] = *buf;
    109		w1_buf[2] = ~(*buf);
    110		w1_write_block(sl->master, w1_buf, 3);
    111
    112		if (w1_read_8(sl->master) == W1_F3A_SUCCESS_CONFIRM_BYTE) {
    113			bytes_written = 1;
    114			goto out;
    115		}
    116		if (w1_reset_resume_command(sl->master))
    117			goto out; /* unrecoverable error */
    118
    119		dev_warn(&sl->dev, "PIO_ACCESS_WRITE error, retries left: %d\n", retries);
    120	}
    121
    122out:
    123	mutex_unlock(&sl->master->bus_mutex);
    124	dev_dbg(&sl->dev, "%s, mutex unlocked, retries: %d\n",
    125		(bytes_written > 0) ? "succeeded" : "error", retries);
    126	return bytes_written;
    127}
    128
    129static BIN_ATTR(output, S_IRUGO | S_IWUSR | S_IWGRP, NULL, output_write, 1);
    130
    131static struct bin_attribute *w1_f3a_bin_attrs[] = {
    132	&bin_attr_state,
    133	&bin_attr_output,
    134	NULL,
    135};
    136
    137static const struct attribute_group w1_f3a_group = {
    138	.bin_attrs = w1_f3a_bin_attrs,
    139};
    140
    141static const struct attribute_group *w1_f3a_groups[] = {
    142	&w1_f3a_group,
    143	NULL,
    144};
    145
    146static const struct w1_family_ops w1_f3a_fops = {
    147	.groups		= w1_f3a_groups,
    148};
    149
    150static struct w1_family w1_family_3a = {
    151	.fid = W1_FAMILY_DS2413,
    152	.fops = &w1_f3a_fops,
    153};
    154module_w1_family(w1_family_3a);
    155
    156MODULE_AUTHOR("Mariusz Bialonczyk <manio@skyboo.net>");
    157MODULE_DESCRIPTION("w1 family 3a driver for DS2413 2 Pin IO");
    158MODULE_LICENSE("GPL");
    159MODULE_ALIAS("w1-family-" __stringify(W1_FAMILY_DS2413));