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