linux_dsm_epyc7002/drivers/platform/chrome/wilco_ec/debugfs.c
Nick Crews 9e2b0e0be6 platform/chrome: wilco_ec: Add h1_gpio status to debugfs
As part of Chrome OS's FAFT (Fully Automated Firmware Testing)
tests, we need to ensure that the H1 chip is properly setting
some GPIO lines. The h1_gpio attribute exposes the state
of the lines:
- ENTRY_TO_FACT_MODE in BIT(0)
- SPI_CHROME_SEL in BIT(1)

There are two reasons that I am exposing this in debugfs,
and not as a GPIO:
1. This is only useful for testing, so end users shouldn't ever
care about this. In fact, if it passes the tests, then the value of
h1_gpio will always be 2, so it would be really uninteresting for users.
2. This GPIO is not connected to, controlled by, or really even related
to the AP. The GPIO runs between the EC and the H1 security chip.

Changes in v4:
- Use "0x02x\n" instead of "02x\n" for format string
- Use DEFINE_DEBUGFS_ATTRIBUTE()
- Add documentation
Changes in v3:
- Fix documentation to correspond with formatting change in v2.
Changes in v2:
- Zero out the unused fields in the request.
- Format result as "%02x\n" instead of as a decimal.

Signed-off-by: Nick Crews <ncrews@chromium.org>
Signed-off-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>
2019-04-16 11:00:36 +02:00

260 lines
6.8 KiB
C

// SPDX-License-Identifier: GPL-2.0
/*
* debugfs attributes for Wilco EC
*
* Copyright 2019 Google LLC
*
* See Documentation/ABI/testing/debugfs-wilco-ec for usage.
*/
#include <linux/ctype.h>
#include <linux/debugfs.h>
#include <linux/fs.h>
#include <linux/module.h>
#include <linux/platform_data/wilco-ec.h>
#include <linux/platform_device.h>
#define DRV_NAME "wilco-ec-debugfs"
/* The 256 raw bytes will take up more space when represented as a hex string */
#define FORMATTED_BUFFER_SIZE (EC_MAILBOX_DATA_SIZE_EXTENDED * 4)
struct wilco_ec_debugfs {
struct wilco_ec_device *ec;
struct dentry *dir;
size_t response_size;
u8 raw_data[EC_MAILBOX_DATA_SIZE_EXTENDED];
u8 formatted_data[FORMATTED_BUFFER_SIZE];
};
static struct wilco_ec_debugfs *debug_info;
/**
* parse_hex_sentence() - Convert a ascii hex representation into byte array.
* @in: Input buffer of ascii.
* @isize: Length of input buffer.
* @out: Output buffer.
* @osize: Length of output buffer, e.g. max number of bytes to parse.
*
* An valid input is a series of ascii hexadecimal numbers, separated by spaces.
* An example valid input is
* " 00 f2 0 000076 6 0 ff"
*
* If an individual "word" within the hex sentence is longer than MAX_WORD_SIZE,
* then the sentence is illegal, and parsing will fail.
*
* Return: Number of bytes parsed, or negative error code on failure.
*/
static int parse_hex_sentence(const char *in, int isize, u8 *out, int osize)
{
int n_parsed = 0;
int word_start = 0;
int word_end;
int word_len;
/* Temp buffer for holding a "word" of chars that represents one byte */
#define MAX_WORD_SIZE 16
char tmp[MAX_WORD_SIZE + 1];
u8 byte;
while (word_start < isize && n_parsed < osize) {
/* Find the start of the next word */
while (word_start < isize && isspace(in[word_start]))
word_start++;
/* reached the end of the input before next word? */
if (word_start >= isize)
break;
/* Find the end of this word */
word_end = word_start;
while (word_end < isize && !isspace(in[word_end]))
word_end++;
/* Copy to a tmp NULL terminated string */
word_len = word_end - word_start;
if (word_len > MAX_WORD_SIZE)
return -EINVAL;
memcpy(tmp, in + word_start, word_len);
tmp[word_len] = '\0';
/*
* Convert from hex string, place in output. If fails to parse,
* just return -EINVAL because specific error code is only
* relevant for this one word, returning it would be confusing.
*/
if (kstrtou8(tmp, 16, &byte))
return -EINVAL;
out[n_parsed++] = byte;
word_start = word_end;
}
return n_parsed;
}
/* The message type takes up two bytes*/
#define TYPE_AND_DATA_SIZE ((EC_MAILBOX_DATA_SIZE) + 2)
static ssize_t raw_write(struct file *file, const char __user *user_buf,
size_t count, loff_t *ppos)
{
char *buf = debug_info->formatted_data;
struct wilco_ec_message msg;
u8 request_data[TYPE_AND_DATA_SIZE];
ssize_t kcount;
int ret;
if (count > FORMATTED_BUFFER_SIZE)
return -EINVAL;
kcount = simple_write_to_buffer(buf, FORMATTED_BUFFER_SIZE, ppos,
user_buf, count);
if (kcount < 0)
return kcount;
ret = parse_hex_sentence(buf, kcount, request_data, TYPE_AND_DATA_SIZE);
if (ret < 0)
return ret;
/* Need at least two bytes for message type and one byte of data */
if (ret < 3)
return -EINVAL;
msg.type = request_data[0] << 8 | request_data[1];
msg.flags = 0;
msg.request_data = request_data + 2;
msg.request_size = ret - 2;
memset(debug_info->raw_data, 0, sizeof(debug_info->raw_data));
msg.response_data = debug_info->raw_data;
msg.response_size = EC_MAILBOX_DATA_SIZE;
/* Telemetry commands use extended response data */
if (msg.type == WILCO_EC_MSG_TELEMETRY_LONG) {
msg.flags |= WILCO_EC_FLAG_EXTENDED_DATA;
msg.response_size = EC_MAILBOX_DATA_SIZE_EXTENDED;
}
ret = wilco_ec_mailbox(debug_info->ec, &msg);
if (ret < 0)
return ret;
debug_info->response_size = ret;
return count;
}
static ssize_t raw_read(struct file *file, char __user *user_buf, size_t count,
loff_t *ppos)
{
int fmt_len = 0;
if (debug_info->response_size) {
fmt_len = hex_dump_to_buffer(debug_info->raw_data,
debug_info->response_size,
16, 1, debug_info->formatted_data,
sizeof(debug_info->formatted_data),
true);
/* Only return response the first time it is read */
debug_info->response_size = 0;
}
return simple_read_from_buffer(user_buf, count, ppos,
debug_info->formatted_data, fmt_len);
}
static const struct file_operations fops_raw = {
.owner = THIS_MODULE,
.read = raw_read,
.write = raw_write,
.llseek = no_llseek,
};
#define CMD_KB_CHROME 0x88
#define SUB_CMD_H1_GPIO 0x0A
struct h1_gpio_status_request {
u8 cmd; /* Always CMD_KB_CHROME */
u8 reserved;
u8 sub_cmd; /* Always SUB_CMD_H1_GPIO */
} __packed;
struct hi_gpio_status_response {
u8 status; /* 0 if allowed */
u8 val; /* BIT(0)=ENTRY_TO_FACT_MODE, BIT(1)=SPI_CHROME_SEL */
} __packed;
static int h1_gpio_get(void *arg, u64 *val)
{
struct wilco_ec_device *ec = arg;
struct h1_gpio_status_request rq;
struct hi_gpio_status_response rs;
struct wilco_ec_message msg;
int ret;
memset(&rq, 0, sizeof(rq));
rq.cmd = CMD_KB_CHROME;
rq.sub_cmd = SUB_CMD_H1_GPIO;
memset(&msg, 0, sizeof(msg));
msg.type = WILCO_EC_MSG_LEGACY;
msg.request_data = &rq;
msg.request_size = sizeof(rq);
msg.response_data = &rs;
msg.response_size = sizeof(rs);
ret = wilco_ec_mailbox(ec, &msg);
if (ret < 0)
return ret;
if (rs.status)
return -EIO;
*val = rs.val;
return 0;
}
DEFINE_DEBUGFS_ATTRIBUTE(fops_h1_gpio, h1_gpio_get, NULL, "0x%02llx\n");
/**
* wilco_ec_debugfs_probe() - Create the debugfs node
* @pdev: The platform device, probably created in core.c
*
* Try to create a debugfs node. If it fails, then we don't want to change
* behavior at all, this is for debugging after all. Just fail silently.
*
* Return: 0 always.
*/
static int wilco_ec_debugfs_probe(struct platform_device *pdev)
{
struct wilco_ec_device *ec = dev_get_drvdata(pdev->dev.parent);
debug_info = devm_kzalloc(&pdev->dev, sizeof(*debug_info), GFP_KERNEL);
if (!debug_info)
return 0;
debug_info->ec = ec;
debug_info->dir = debugfs_create_dir("wilco_ec", NULL);
if (!debug_info->dir)
return 0;
debugfs_create_file("raw", 0644, debug_info->dir, NULL, &fops_raw);
debugfs_create_file("h1_gpio", 0444, debug_info->dir, ec,
&fops_h1_gpio);
return 0;
}
static int wilco_ec_debugfs_remove(struct platform_device *pdev)
{
debugfs_remove_recursive(debug_info->dir);
return 0;
}
static struct platform_driver wilco_ec_debugfs_driver = {
.driver = {
.name = DRV_NAME,
},
.probe = wilco_ec_debugfs_probe,
.remove = wilco_ec_debugfs_remove,
};
module_platform_driver(wilco_ec_debugfs_driver);
MODULE_ALIAS("platform:" DRV_NAME);
MODULE_AUTHOR("Nick Crews <ncrews@chromium.org>");
MODULE_LICENSE("GPL v2");
MODULE_DESCRIPTION("Wilco EC debugfs driver");