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 
oppanel_llseek(struct file * filp,loff_t offset,int whence)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 
oppanel_read(struct file * filp,char __user * userbuf,size_t len,loff_t * f_pos)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 
__op_panel_update_display(void)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 		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 
oppanel_write(struct file * filp,const char __user * userbuf,size_t len,loff_t * f_pos)89 static 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 
oppanel_open(struct inode * inode,struct file * filp)115 static 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 
oppanel_release(struct inode * inode,struct file * filp)124 static int oppanel_release(struct inode *inode, struct file *filp)
125 {
126 	mutex_unlock(&oppanel_mutex);
127 	return 0;
128 }
129 
130 static 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 
139 static struct miscdevice oppanel_dev = {
140 	.minor		= MISC_DYNAMIC_MINOR,
141 	.name		= "op_panel",
142 	.fops		= &oppanel_fops
143 };
144 
oppanel_probe(struct platform_device * pdev)145 static 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 
191 free_oppanel:
192 	kfree(oppanel_lines);
193 free_oppanel_data:
194 	kfree(oppanel_data);
195 	return rc;
196 }
197 
oppanel_remove(struct platform_device * pdev)198 static 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 
206 static const struct of_device_id oppanel_match[] = {
207 	{ .compatible = "ibm,opal-oppanel" },
208 	{ },
209 };
210 
211 static 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 
220 module_platform_driver(oppanel_driver);
221 
222 MODULE_DEVICE_TABLE(of, oppanel_match);
223 MODULE_LICENSE("GPL v2");
224 MODULE_DESCRIPTION("PowerNV Operator Panel LCD Display Driver");
225 MODULE_AUTHOR("Suraj Jitindar Singh <sjitindarsingh@gmail.com>");
226