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 
32 static DEFINE_MUTEX(oppanel_mutex);
33 
34 static u32		num_lines, oppanel_size;
35 static oppanel_line_t	*oppanel_lines;
36 static char		*oppanel_data;
37 
38 static 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 
43 static 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 
50 static 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 	case OPAL_SUCCESS:
79 		break;
80 	default:
81 		pr_debug("OPAL write op-panel call failed [rc=%d]\n", rc);
82 	}
83 
84 	opal_async_release_token(token);
85 	return rc;
86 }
87 
88 static ssize_t oppanel_write(struct file *filp, const char __user *userbuf,
89 			     size_t len, loff_t *f_pos)
90 {
91 	loff_t f_pos_prev = *f_pos;
92 	ssize_t ret;
93 	int rc;
94 
95 	if (!*f_pos)
96 		memset(oppanel_data, ' ', oppanel_size);
97 	else if (*f_pos >= oppanel_size)
98 		return -EFBIG;
99 
100 	ret = simple_write_to_buffer(oppanel_data, oppanel_size, f_pos, userbuf,
101 			len);
102 	if (ret > 0) {
103 		rc = __op_panel_update_display();
104 		if (rc != OPAL_SUCCESS) {
105 			pr_err_ratelimited("OPAL call failed to write to op panel display [rc=%d]\n",
106 				rc);
107 			*f_pos = f_pos_prev;
108 			return -EIO;
109 		}
110 	}
111 	return ret;
112 }
113 
114 static int oppanel_open(struct inode *inode, struct file *filp)
115 {
116 	if (!mutex_trylock(&oppanel_mutex)) {
117 		pr_debug("Device Busy\n");
118 		return -EBUSY;
119 	}
120 	return 0;
121 }
122 
123 static int oppanel_release(struct inode *inode, struct file *filp)
124 {
125 	mutex_unlock(&oppanel_mutex);
126 	return 0;
127 }
128 
129 static const struct file_operations oppanel_fops = {
130 	.owner		= THIS_MODULE,
131 	.llseek		= oppanel_llseek,
132 	.read		= oppanel_read,
133 	.write		= oppanel_write,
134 	.open		= oppanel_open,
135 	.release	= oppanel_release
136 };
137 
138 static struct miscdevice oppanel_dev = {
139 	.minor		= MISC_DYNAMIC_MINOR,
140 	.name		= "op_panel",
141 	.fops		= &oppanel_fops
142 };
143 
144 static int oppanel_probe(struct platform_device *pdev)
145 {
146 	struct device_node *np = pdev->dev.of_node;
147 	u32 line_len;
148 	int rc, i;
149 
150 	rc = of_property_read_u32(np, "#length", &line_len);
151 	if (rc) {
152 		pr_err_ratelimited("Operator panel length property not found\n");
153 		return rc;
154 	}
155 	rc = of_property_read_u32(np, "#lines", &num_lines);
156 	if (rc) {
157 		pr_err_ratelimited("Operator panel lines property not found\n");
158 		return rc;
159 	}
160 	oppanel_size = line_len * num_lines;
161 
162 	pr_devel("Operator panel of size %u found with %u lines of length %u\n",
163 			oppanel_size, num_lines, line_len);
164 
165 	oppanel_data = kcalloc(oppanel_size, sizeof(*oppanel_data), GFP_KERNEL);
166 	if (!oppanel_data)
167 		return -ENOMEM;
168 
169 	oppanel_lines = kcalloc(num_lines, sizeof(oppanel_line_t), GFP_KERNEL);
170 	if (!oppanel_lines) {
171 		rc = -ENOMEM;
172 		goto free_oppanel_data;
173 	}
174 
175 	memset(oppanel_data, ' ', oppanel_size);
176 	for (i = 0; i < num_lines; i++) {
177 		oppanel_lines[i].line_len = cpu_to_be64(line_len);
178 		oppanel_lines[i].line = cpu_to_be64(__pa(&oppanel_data[i *
179 						line_len]));
180 	}
181 
182 	rc = misc_register(&oppanel_dev);
183 	if (rc) {
184 		pr_err_ratelimited("Failed to register as misc device\n");
185 		goto free_oppanel;
186 	}
187 
188 	return 0;
189 
190 free_oppanel:
191 	kfree(oppanel_lines);
192 free_oppanel_data:
193 	kfree(oppanel_data);
194 	return rc;
195 }
196 
197 static int oppanel_remove(struct platform_device *pdev)
198 {
199 	misc_deregister(&oppanel_dev);
200 	kfree(oppanel_lines);
201 	kfree(oppanel_data);
202 	return 0;
203 }
204 
205 static const struct of_device_id oppanel_match[] = {
206 	{ .compatible = "ibm,opal-oppanel" },
207 	{ },
208 };
209 
210 static struct platform_driver oppanel_driver = {
211 	.driver	= {
212 		.name		= "powernv-op-panel",
213 		.of_match_table	= oppanel_match,
214 	},
215 	.probe	= oppanel_probe,
216 	.remove	= oppanel_remove,
217 };
218 
219 module_platform_driver(oppanel_driver);
220 
221 MODULE_DEVICE_TABLE(of, oppanel_match);
222 MODULE_LICENSE("GPL v2");
223 MODULE_DESCRIPTION("PowerNV Operator Panel LCD Display Driver");
224 MODULE_AUTHOR("Suraj Jitindar Singh <sjitindarsingh@gmail.com>");
225