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// SPDX-License-Identifier: GPL-2.0-only
/*
* OPAL Operator Panel Display Driver
*
* Copyright 2016, Suraj Jitindar Singh, IBM Corporation.
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/init.h>
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/fs.h>
#include <linux/device.h>
#include <linux/errno.h>
#include <linux/mutex.h>
#include <linux/of.h>
#include <linux/slab.h>
#include <linux/platform_device.h>
#include <linux/miscdevice.h>
#include <asm/opal.h>
/*
* This driver creates a character device (/dev/op_panel) which exposes the
* operator panel (character LCD display) on IBM Power Systems machines
* with FSPs.
* A character buffer written to the device will be displayed on the
* operator panel.
*/
static DEFINE_MUTEX(oppanel_mutex);
static u32 num_lines, oppanel_size;
static oppanel_line_t *oppanel_lines;
static char *oppanel_data;
static loff_t oppanel_llseek(struct file *filp, loff_t offset, int whence)
{
return fixed_size_llseek(filp, offset, whence, oppanel_size);
}
static ssize_t oppanel_read(struct file *filp, char __user *userbuf, size_t len,
loff_t *f_pos)
{
return simple_read_from_buffer(userbuf, len, f_pos, oppanel_data,
oppanel_size);
}
static int __op_panel_update_display(void)
{
struct opal_msg msg;
int rc, token;
token = opal_async_get_token_interruptible();
if (token < 0) {
if (token != -ERESTARTSYS)
pr_debug("Couldn't get OPAL async token [token=%d]\n",
token);
return token;
}
rc = opal_write_oppanel_async(token, oppanel_lines, num_lines);
switch (rc) {
case OPAL_ASYNC_COMPLETION:
rc = opal_async_wait_response(token, &msg);
if (rc) {
pr_debug("Failed to wait for async response [rc=%d]\n",
rc);
break;
}
rc = opal_get_async_rc(msg);
if (rc != OPAL_SUCCESS) {
pr_debug("OPAL async call returned failed [rc=%d]\n",
rc);
break;
}
case OPAL_SUCCESS:
break;
default:
pr_debug("OPAL write op-panel call failed [rc=%d]\n", rc);
}
opal_async_release_token(token);
return rc;
}
static ssize_t oppanel_write(struct file *filp, const char __user *userbuf,
size_t len, loff_t *f_pos)
{
loff_t f_pos_prev = *f_pos;
ssize_t ret;
int rc;
if (!*f_pos)
memset(oppanel_data, ' ', oppanel_size);
else if (*f_pos >= oppanel_size)
return -EFBIG;
ret = simple_write_to_buffer(oppanel_data, oppanel_size, f_pos, userbuf,
len);
if (ret > 0) {
rc = __op_panel_update_display();
if (rc != OPAL_SUCCESS) {
pr_err_ratelimited("OPAL call failed to write to op panel display [rc=%d]\n",
rc);
*f_pos = f_pos_prev;
return -EIO;
}
}
return ret;
}
static int oppanel_open(struct inode *inode, struct file *filp)
{
if (!mutex_trylock(&oppanel_mutex)) {
pr_debug("Device Busy\n");
return -EBUSY;
}
return 0;
}
static int oppanel_release(struct inode *inode, struct file *filp)
{
mutex_unlock(&oppanel_mutex);
return 0;
}
static const struct file_operations oppanel_fops = {
.owner = THIS_MODULE,
.llseek = oppanel_llseek,
.read = oppanel_read,
.write = oppanel_write,
.open = oppanel_open,
.release = oppanel_release
};
static struct miscdevice oppanel_dev = {
.minor = MISC_DYNAMIC_MINOR,
.name = "op_panel",
.fops = &oppanel_fops
};
static int oppanel_probe(struct platform_device *pdev)
{
struct device_node *np = pdev->dev.of_node;
u32 line_len;
int rc, i;
rc = of_property_read_u32(np, "#length", &line_len);
if (rc) {
pr_err_ratelimited("Operator panel length property not found\n");
return rc;
}
rc = of_property_read_u32(np, "#lines", &num_lines);
if (rc) {
pr_err_ratelimited("Operator panel lines property not found\n");
return rc;
}
oppanel_size = line_len * num_lines;
pr_devel("Operator panel of size %u found with %u lines of length %u\n",
oppanel_size, num_lines, line_len);
oppanel_data = kcalloc(oppanel_size, sizeof(*oppanel_data), GFP_KERNEL);
if (!oppanel_data)
return -ENOMEM;
oppanel_lines = kcalloc(num_lines, sizeof(oppanel_line_t), GFP_KERNEL);
if (!oppanel_lines) {
rc = -ENOMEM;
goto free_oppanel_data;
}
memset(oppanel_data, ' ', oppanel_size);
for (i = 0; i < num_lines; i++) {
oppanel_lines[i].line_len = cpu_to_be64(line_len);
oppanel_lines[i].line = cpu_to_be64(__pa(&oppanel_data[i *
line_len]));
}
rc = misc_register(&oppanel_dev);
if (rc) {
pr_err_ratelimited("Failed to register as misc device\n");
goto free_oppanel;
}
return 0;
free_oppanel:
kfree(oppanel_lines);
free_oppanel_data:
kfree(oppanel_data);
return rc;
}
static int oppanel_remove(struct platform_device *pdev)
{
misc_deregister(&oppanel_dev);
kfree(oppanel_lines);
kfree(oppanel_data);
return 0;
}
static const struct of_device_id oppanel_match[] = {
{ .compatible = "ibm,opal-oppanel" },
{ },
};
static struct platform_driver oppanel_driver = {
.driver = {
.name = "powernv-op-panel",
.of_match_table = oppanel_match,
},
.probe = oppanel_probe,
.remove = oppanel_remove,
};
module_platform_driver(oppanel_driver);
MODULE_DEVICE_TABLE(of, oppanel_match);
MODULE_LICENSE("GPL v2");
MODULE_DESCRIPTION("PowerNV Operator Panel LCD Display Driver");
MODULE_AUTHOR("Suraj Jitindar Singh <sjitindarsingh@gmail.com>");
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