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(file: filp, offset, whence, size: 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(to: userbuf, count: len, ppos: f_pos, from: oppanel_data, |
47 | available: 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 | 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 | |
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(to: oppanel_data, available: oppanel_size, ppos: f_pos, from: userbuf, |
102 | count: 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 | |
115 | static int oppanel_open(struct inode *inode, struct file *filp) |
116 | { |
117 | if (!mutex_trylock(lock: &oppanel_mutex)) { |
118 | pr_debug("Device Busy\n" ); |
119 | return -EBUSY; |
120 | } |
121 | return 0; |
122 | } |
123 | |
124 | static int oppanel_release(struct inode *inode, struct file *filp) |
125 | { |
126 | mutex_unlock(lock: &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 | |
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, propname: "#length" , out_value: &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, propname: "#lines" , out_value: &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(n: oppanel_size, 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(misc: &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(objp: oppanel_lines); |
193 | free_oppanel_data: |
194 | kfree(objp: oppanel_data); |
195 | return rc; |
196 | } |
197 | |
198 | static int oppanel_remove(struct platform_device *pdev) |
199 | { |
200 | misc_deregister(misc: &oppanel_dev); |
201 | kfree(objp: oppanel_lines); |
202 | kfree(objp: 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 | |