2 * OPAL Operator Panel Display Driver
4 * Copyright 2016, Suraj Jitindar Singh, IBM Corporation.
7 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
9 #include <linux/init.h>
10 #include <linux/module.h>
11 #include <linux/kernel.h>
13 #include <linux/device.h>
14 #include <linux/errno.h>
15 #include <linux/mutex.h>
17 #include <linux/slab.h>
18 #include <linux/platform_device.h>
19 #include <linux/miscdevice.h>
24 * This driver creates a character device (/dev/op_panel) which exposes the
25 * operator panel (character LCD display) on IBM Power Systems machines
27 * A character buffer written to the device will be displayed on the
31 static DEFINE_MUTEX(oppanel_mutex);
33 static u32 num_lines, oppanel_size;
34 static oppanel_line_t *oppanel_lines;
35 static char *oppanel_data;
37 static loff_t oppanel_llseek(struct file *filp, loff_t offset, int whence)
39 return fixed_size_llseek(filp, offset, whence, oppanel_size);
42 static ssize_t oppanel_read(struct file *filp, char __user *userbuf, size_t len,
45 return simple_read_from_buffer(userbuf, len, f_pos, oppanel_data,
49 static int __op_panel_update_display(void)
54 token = opal_async_get_token_interruptible();
56 if (token != -ERESTARTSYS)
57 pr_debug("Couldn't get OPAL async token [token=%d]\n",
62 rc = opal_write_oppanel_async(token, oppanel_lines, num_lines);
64 case OPAL_ASYNC_COMPLETION:
65 rc = opal_async_wait_response(token, &msg);
67 pr_debug("Failed to wait for async response [rc=%d]\n",
71 rc = opal_get_async_rc(msg);
72 if (rc != OPAL_SUCCESS) {
73 pr_debug("OPAL async call returned failed [rc=%d]\n",
80 pr_debug("OPAL write op-panel call failed [rc=%d]\n", rc);
83 opal_async_release_token(token);
87 static ssize_t oppanel_write(struct file *filp, const char __user *userbuf,
88 size_t len, loff_t *f_pos)
90 loff_t f_pos_prev = *f_pos;
95 memset(oppanel_data, ' ', oppanel_size);
96 else if (*f_pos >= oppanel_size)
99 ret = simple_write_to_buffer(oppanel_data, oppanel_size, f_pos, userbuf,
102 rc = __op_panel_update_display();
103 if (rc != OPAL_SUCCESS) {
104 pr_err_ratelimited("OPAL call failed to write to op panel display [rc=%d]\n",
113 static int oppanel_open(struct inode *inode, struct file *filp)
115 if (!mutex_trylock(&oppanel_mutex)) {
116 pr_debug("Device Busy\n");
122 static int oppanel_release(struct inode *inode, struct file *filp)
124 mutex_unlock(&oppanel_mutex);
128 static const struct file_operations oppanel_fops = {
129 .owner = THIS_MODULE,
130 .llseek = oppanel_llseek,
131 .read = oppanel_read,
132 .write = oppanel_write,
133 .open = oppanel_open,
134 .release = oppanel_release
137 static struct miscdevice oppanel_dev = {
138 .minor = MISC_DYNAMIC_MINOR,
140 .fops = &oppanel_fops
143 static int oppanel_probe(struct platform_device *pdev)
145 struct device_node *np = pdev->dev.of_node;
149 rc = of_property_read_u32(np, "#length", &line_len);
151 pr_err_ratelimited("Operator panel length property not found\n");
154 rc = of_property_read_u32(np, "#lines", &num_lines);
156 pr_err_ratelimited("Operator panel lines property not found\n");
159 oppanel_size = line_len * num_lines;
161 pr_devel("Operator panel of size %u found with %u lines of length %u\n",
162 oppanel_size, num_lines, line_len);
164 oppanel_data = kcalloc(oppanel_size, sizeof(*oppanel_data), GFP_KERNEL);
168 oppanel_lines = kcalloc(num_lines, sizeof(oppanel_line_t), GFP_KERNEL);
169 if (!oppanel_lines) {
171 goto free_oppanel_data;
174 memset(oppanel_data, ' ', oppanel_size);
175 for (i = 0; i < num_lines; i++) {
176 oppanel_lines[i].line_len = cpu_to_be64(line_len);
177 oppanel_lines[i].line = cpu_to_be64(__pa(&oppanel_data[i *
181 rc = misc_register(&oppanel_dev);
183 pr_err_ratelimited("Failed to register as misc device\n");
190 kfree(oppanel_lines);
196 static int oppanel_remove(struct platform_device *pdev)
198 misc_deregister(&oppanel_dev);
199 kfree(oppanel_lines);
204 static const struct of_device_id oppanel_match[] = {
205 { .compatible = "ibm,opal-oppanel" },
209 static struct platform_driver oppanel_driver = {
211 .name = "powernv-op-panel",
212 .of_match_table = oppanel_match,
214 .probe = oppanel_probe,
215 .remove = oppanel_remove,
218 module_platform_driver(oppanel_driver);
220 MODULE_DEVICE_TABLE(of, oppanel_match);
221 MODULE_LICENSE("GPL v2");
222 MODULE_DESCRIPTION("PowerNV Operator Panel LCD Display Driver");
223 MODULE_AUTHOR("Suraj Jitindar Singh <sjitindarsingh@gmail.com>");