drivers/firmware/xilinx/zynqmp-debug.c

// SPDX-License-Identifier: GPL-2.0
/*
 * Xilinx Zynq MPSoC Firmware layer for debugfs APIs
 *
 *  Copyright (C) 2014-2018 Xilinx, Inc.
 *
 *  Michal Simek <michal.simek@xilinx.com>
 *  Davorin Mista <davorin.mista@aggios.com>
 *  Jolly Shah <jollys@xilinx.com>
 *  Rajan Vaja <rajanv@xilinx.com>
 */

#include <linux/compiler.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/debugfs.h>
#include <linux/uaccess.h>

#include <linux/firmware/xlnx-zynqmp.h>
#include "zynqmp-debug.h"

#define PM_API_NAME_LEN			50

struct pm_api_info {
	u32 api_id;
	char api_name[PM_API_NAME_LEN];
	char api_name_len;
};

static char debugfs_buf[PAGE_SIZE];

#define PM_API(id)		 {id, #id, strlen(#id)}
static struct pm_api_info pm_api_list[] = {
	PM_API(PM_GET_API_VERSION),
};

struct dentry *firmware_debugfs_root;

/**
 * zynqmp_pm_argument_value() - Extract argument value from a PM-API request
 * @arg:	Entered PM-API argument in string format
 *
 * Return: Argument value in unsigned integer format on success
 *	   0 otherwise
 */
static u64 zynqmp_pm_argument_value(char *arg)
{
	u64 value;

	if (!arg)
		return 0;

	if (!kstrtou64(arg, 0, &value))
		return value;

	return 0;
}

/**
 * get_pm_api_id() - Extract API-ID from a PM-API request
 * @pm_api_req:		Entered PM-API argument in string format
 * @pm_id:		API-ID
 *
 * Return: 0 on success else error code
 */
static int get_pm_api_id(char *pm_api_req, u32 *pm_id)
{
	int i;

	for (i = 0; i < ARRAY_SIZE(pm_api_list) ; i++) {
		if (!strncasecmp(pm_api_req, pm_api_list[i].api_name,
				 pm_api_list[i].api_name_len)) {
			*pm_id = pm_api_list[i].api_id;
			break;
		}
	}

	/* If no name was entered look for PM-API ID instead */
	if (i == ARRAY_SIZE(pm_api_list) && kstrtouint(pm_api_req, 10, pm_id))
		return -EINVAL;

	return 0;
}

static int process_api_request(u32 pm_id, u64 *pm_api_arg, u32 *pm_api_ret)
{
	const struct zynqmp_eemi_ops *eemi_ops = zynqmp_pm_get_eemi_ops();
	u32 pm_api_version;
	int ret;

	if (!eemi_ops)
		return -ENXIO;

	switch (pm_id) {
	case PM_GET_API_VERSION:
		ret = eemi_ops->get_api_version(&pm_api_version);
		sprintf(debugfs_buf, "PM-API Version = %d.%d\n",
			pm_api_version >> 16, pm_api_version & 0xffff);
		break;
	default:
		sprintf(debugfs_buf, "Unsupported PM-API request\n");
		ret = -EINVAL;
	}

	return ret;
}

/**
 * zynqmp_pm_debugfs_api_write() - debugfs write function
 * @file:	User file
 * @ptr:	User entered PM-API string
 * @len:	Length of the userspace buffer
 * @off:	Offset within the file
 *
 * Used for triggering pm api functions by writing
 * echo <pm_api_id>	> /sys/kernel/debug/zynqmp_pm/power or
 * echo <pm_api_name>	> /sys/kernel/debug/zynqmp_pm/power
 *
 * Return: Number of bytes copied if PM-API request succeeds,
 *	   the corresponding error code otherwise
 */
static ssize_t zynqmp_pm_debugfs_api_write(struct file *file,
					   const char __user *ptr, size_t len,
					   loff_t *off)
{
	char *kern_buff, *tmp_buff;
	char *pm_api_req;
	u32 pm_id = 0;
	u64 pm_api_arg[4] = {0, 0, 0, 0};
	/* Return values from PM APIs calls */
	u32 pm_api_ret[4] = {0, 0, 0, 0};

	int ret;
	int i = 0;

	strcpy(debugfs_buf, "");

	if (*off != 0 || len == 0)
		return -EINVAL;

	kern_buff = kzalloc(len, GFP_KERNEL);
	if (!kern_buff)
		return -ENOMEM;

	tmp_buff = kern_buff;

	ret = strncpy_from_user(kern_buff, ptr, len);
	if (ret < 0) {
		ret = -EFAULT;
		goto err;
	}

	/* Read the API name from a user request */
	pm_api_req = strsep(&kern_buff, " ");

	ret = get_pm_api_id(pm_api_req, &pm_id);
	if (ret < 0)
		goto err;

	/* Read node_id and arguments from the PM-API request */
	pm_api_req = strsep(&kern_buff, " ");
	while ((i < ARRAY_SIZE(pm_api_arg)) && pm_api_req) {
		pm_api_arg[i++] = zynqmp_pm_argument_value(pm_api_req);
		pm_api_req = strsep(&kern_buff, " ");
	}

	ret = process_api_request(pm_id, pm_api_arg, pm_api_ret);

err:
	kfree(tmp_buff);
	if (ret)
		return ret;

	return len;
}

/**
 * zynqmp_pm_debugfs_api_read() - debugfs read function
 * @file:	User file
 * @ptr:	Requested pm_api_version string
 * @len:	Length of the userspace buffer
 * @off:	Offset within the file
 *
 * Return: Length of the version string on success
 *	   else error code
 */
static ssize_t zynqmp_pm_debugfs_api_read(struct file *file, char __user *ptr,
					  size_t len, loff_t *off)
{
	return simple_read_from_buffer(ptr, len, off, debugfs_buf,
				       strlen(debugfs_buf));
}

/* Setup debugfs fops */
static const struct file_operations fops_zynqmp_pm_dbgfs = {
	.owner = THIS_MODULE,
	.write = zynqmp_pm_debugfs_api_write,
	.read = zynqmp_pm_debugfs_api_read,
};

/**
 * zynqmp_pm_api_debugfs_init - Initialize debugfs interface
 *
 * Return:	None
 */
void zynqmp_pm_api_debugfs_init(void)
{
	/* Initialize debugfs interface */
	firmware_debugfs_root = debugfs_create_dir("zynqmp-firmware", NULL);
	debugfs_create_file("pm", 0660, firmware_debugfs_root, NULL,
			    &fops_zynqmp_pm_dbgfs);
}

/**
 * zynqmp_pm_api_debugfs_exit - Remove debugfs interface
 *
 * Return:	None
 */
void zynqmp_pm_api_debugfs_exit(void)
{
	debugfs_remove_recursive(firmware_debugfs_root);
}