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 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(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 } 114 115 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 } 123 124 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 }; 144 145 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 } 197 198 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