1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * OPAL Operator Panel Display Driver
4 *
5 * Copyright 2016, Suraj Jitindar Singh, IBM Corporation.
6 */
7
8#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
9
10#include <linux/init.h>
11#include <linux/module.h>
12#include <linux/kernel.h>
13#include <linux/fs.h>
14#include <linux/device.h>
15#include <linux/errno.h>
16#include <linux/mutex.h>
17#include <linux/of.h>
18#include <linux/slab.h>
19#include <linux/platform_device.h>
20#include <linux/miscdevice.h>
21
22#include <asm/opal.h>
23
24/*
25 * This driver creates a character device (/dev/op_panel) which exposes the
26 * operator panel (character LCD display) on IBM Power Systems machines
27 * with FSPs.
28 * A character buffer written to the device will be displayed on the
29 * operator panel.
30 */
31
32static DEFINE_MUTEX(oppanel_mutex);
33
34static u32		num_lines, oppanel_size;
35static oppanel_line_t	*oppanel_lines;
36static char		*oppanel_data;
37
38static loff_t oppanel_llseek(struct file *filp, loff_t offset, int whence)
39{
40	return fixed_size_llseek(filp, offset, whence, oppanel_size);
41}
42
43static ssize_t oppanel_read(struct file *filp, char __user *userbuf, size_t len,
44			    loff_t *f_pos)
45{
46	return simple_read_from_buffer(userbuf, len, f_pos, oppanel_data,
47			oppanel_size);
48}
49
50static int __op_panel_update_display(void)
51{
52	struct opal_msg msg;
53	int rc, token;
54
55	token = opal_async_get_token_interruptible();
56	if (token < 0) {
57		if (token != -ERESTARTSYS)
58			pr_debug("Couldn't get OPAL async token [token=%d]\n",
59				token);
60		return token;
61	}
62
63	rc = opal_write_oppanel_async(token, oppanel_lines, num_lines);
64	switch (rc) {
65	case OPAL_ASYNC_COMPLETION:
66		rc = opal_async_wait_response(token, &msg);
67		if (rc) {
68			pr_debug("Failed to wait for async response [rc=%d]\n",
69				rc);
70			break;
71		}
72		rc = opal_get_async_rc(msg);
73		if (rc != OPAL_SUCCESS) {
74			pr_debug("OPAL async call returned failed [rc=%d]\n",
75				rc);
76			break;
77		}
78		break;
79	case OPAL_SUCCESS:
80		break;
81	default:
82		pr_debug("OPAL write op-panel call failed [rc=%d]\n", rc);
83	}
84
85	opal_async_release_token(token);
86	return rc;
87}
88
89static ssize_t oppanel_write(struct file *filp, const char __user *userbuf,
90			     size_t len, loff_t *f_pos)
91{
92	loff_t f_pos_prev = *f_pos;
93	ssize_t ret;
94	int rc;
95
96	if (!*f_pos)
97		memset(oppanel_data, ' ', oppanel_size);
98	else if (*f_pos >= oppanel_size)
99		return -EFBIG;
100
101	ret = simple_write_to_buffer(oppanel_data, oppanel_size, f_pos, userbuf,
102			len);
103	if (ret > 0) {
104		rc = __op_panel_update_display();
105		if (rc != OPAL_SUCCESS) {
106			pr_err_ratelimited("OPAL call failed to write to op panel display [rc=%d]\n",
107				rc);
108			*f_pos = f_pos_prev;
109			return -EIO;
110		}
111	}
112	return ret;
113}
114
115static int oppanel_open(struct inode *inode, struct file *filp)
116{
117	if (!mutex_trylock(&oppanel_mutex)) {
118		pr_debug("Device Busy\n");
119		return -EBUSY;
120	}
121	return 0;
122}
123
124static int oppanel_release(struct inode *inode, struct file *filp)
125{
126	mutex_unlock(&oppanel_mutex);
127	return 0;
128}
129
130static const struct file_operations oppanel_fops = {
131	.owner		= THIS_MODULE,
132	.llseek		= oppanel_llseek,
133	.read		= oppanel_read,
134	.write		= oppanel_write,
135	.open		= oppanel_open,
136	.release	= oppanel_release
137};
138
139static struct miscdevice oppanel_dev = {
140	.minor		= MISC_DYNAMIC_MINOR,
141	.name		= "op_panel",
142	.fops		= &oppanel_fops
143};
144
145static int oppanel_probe(struct platform_device *pdev)
146{
147	struct device_node *np = pdev->dev.of_node;
148	u32 line_len;
149	int rc, i;
150
151	rc = of_property_read_u32(np, "#length", &line_len);
152	if (rc) {
153		pr_err_ratelimited("Operator panel length property not found\n");
154		return rc;
155	}
156	rc = of_property_read_u32(np, "#lines", &num_lines);
157	if (rc) {
158		pr_err_ratelimited("Operator panel lines property not found\n");
159		return rc;
160	}
161	oppanel_size = line_len * num_lines;
162
163	pr_devel("Operator panel of size %u found with %u lines of length %u\n",
164			oppanel_size, num_lines, line_len);
165
166	oppanel_data = kcalloc(oppanel_size, sizeof(*oppanel_data), GFP_KERNEL);
167	if (!oppanel_data)
168		return -ENOMEM;
169
170	oppanel_lines = kcalloc(num_lines, sizeof(oppanel_line_t), GFP_KERNEL);
171	if (!oppanel_lines) {
172		rc = -ENOMEM;
173		goto free_oppanel_data;
174	}
175
176	memset(oppanel_data, ' ', oppanel_size);
177	for (i = 0; i < num_lines; i++) {
178		oppanel_lines[i].line_len = cpu_to_be64(line_len);
179		oppanel_lines[i].line = cpu_to_be64(__pa(&oppanel_data[i *
180						line_len]));
181	}
182
183	rc = misc_register(&oppanel_dev);
184	if (rc) {
185		pr_err_ratelimited("Failed to register as misc device\n");
186		goto free_oppanel;
187	}
188
189	return 0;
190
191free_oppanel:
192	kfree(oppanel_lines);
193free_oppanel_data:
194	kfree(oppanel_data);
195	return rc;
196}
197
198static int oppanel_remove(struct platform_device *pdev)
199{
200	misc_deregister(&oppanel_dev);
201	kfree(oppanel_lines);
202	kfree(oppanel_data);
203	return 0;
204}
205
206static const struct of_device_id oppanel_match[] = {
207	{ .compatible = "ibm,opal-oppanel" },
208	{ },
209};
210
211static struct platform_driver oppanel_driver = {
212	.driver	= {
213		.name		= "powernv-op-panel",
214		.of_match_table	= oppanel_match,
215	},
216	.probe	= oppanel_probe,
217	.remove	= oppanel_remove,
218};
219
220module_platform_driver(oppanel_driver);
221
222MODULE_DEVICE_TABLE(of, oppanel_match);
223MODULE_LICENSE("GPL v2");
224MODULE_DESCRIPTION("PowerNV Operator Panel LCD Display Driver");
225MODULE_AUTHOR("Suraj Jitindar Singh <sjitindarsingh@gmail.com>");
226