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 case OPAL_SUCCESS: 79 break; 80 default: 81 pr_debug("OPAL write op-panel call failed [rc=%d]\n", rc); 82 } 83 84 opal_async_release_token(token); 85 return rc; 86 } 87 88 static ssize_t oppanel_write(struct file *filp, const char __user *userbuf, 89 size_t len, loff_t *f_pos) 90 { 91 loff_t f_pos_prev = *f_pos; 92 ssize_t ret; 93 int rc; 94 95 if (!*f_pos) 96 memset(oppanel_data, ' ', oppanel_size); 97 else if (*f_pos >= oppanel_size) 98 return -EFBIG; 99 100 ret = simple_write_to_buffer(oppanel_data, oppanel_size, f_pos, userbuf, 101 len); 102 if (ret > 0) { 103 rc = __op_panel_update_display(); 104 if (rc != OPAL_SUCCESS) { 105 pr_err_ratelimited("OPAL call failed to write to op panel display [rc=%d]\n", 106 rc); 107 *f_pos = f_pos_prev; 108 return -EIO; 109 } 110 } 111 return ret; 112 } 113 114 static int oppanel_open(struct inode *inode, struct file *filp) 115 { 116 if (!mutex_trylock(&oppanel_mutex)) { 117 pr_debug("Device Busy\n"); 118 return -EBUSY; 119 } 120 return 0; 121 } 122 123 static int oppanel_release(struct inode *inode, struct file *filp) 124 { 125 mutex_unlock(&oppanel_mutex); 126 return 0; 127 } 128 129 static const struct file_operations oppanel_fops = { 130 .owner = THIS_MODULE, 131 .llseek = oppanel_llseek, 132 .read = oppanel_read, 133 .write = oppanel_write, 134 .open = oppanel_open, 135 .release = oppanel_release 136 }; 137 138 static struct miscdevice oppanel_dev = { 139 .minor = MISC_DYNAMIC_MINOR, 140 .name = "op_panel", 141 .fops = &oppanel_fops 142 }; 143 144 static int oppanel_probe(struct platform_device *pdev) 145 { 146 struct device_node *np = pdev->dev.of_node; 147 u32 line_len; 148 int rc, i; 149 150 rc = of_property_read_u32(np, "#length", &line_len); 151 if (rc) { 152 pr_err_ratelimited("Operator panel length property not found\n"); 153 return rc; 154 } 155 rc = of_property_read_u32(np, "#lines", &num_lines); 156 if (rc) { 157 pr_err_ratelimited("Operator panel lines property not found\n"); 158 return rc; 159 } 160 oppanel_size = line_len * num_lines; 161 162 pr_devel("Operator panel of size %u found with %u lines of length %u\n", 163 oppanel_size, num_lines, line_len); 164 165 oppanel_data = kcalloc(oppanel_size, sizeof(*oppanel_data), GFP_KERNEL); 166 if (!oppanel_data) 167 return -ENOMEM; 168 169 oppanel_lines = kcalloc(num_lines, sizeof(oppanel_line_t), GFP_KERNEL); 170 if (!oppanel_lines) { 171 rc = -ENOMEM; 172 goto free_oppanel_data; 173 } 174 175 memset(oppanel_data, ' ', oppanel_size); 176 for (i = 0; i < num_lines; i++) { 177 oppanel_lines[i].line_len = cpu_to_be64(line_len); 178 oppanel_lines[i].line = cpu_to_be64(__pa(&oppanel_data[i * 179 line_len])); 180 } 181 182 rc = misc_register(&oppanel_dev); 183 if (rc) { 184 pr_err_ratelimited("Failed to register as misc device\n"); 185 goto free_oppanel; 186 } 187 188 return 0; 189 190 free_oppanel: 191 kfree(oppanel_lines); 192 free_oppanel_data: 193 kfree(oppanel_data); 194 return rc; 195 } 196 197 static int oppanel_remove(struct platform_device *pdev) 198 { 199 misc_deregister(&oppanel_dev); 200 kfree(oppanel_lines); 201 kfree(oppanel_data); 202 return 0; 203 } 204 205 static const struct of_device_id oppanel_match[] = { 206 { .compatible = "ibm,opal-oppanel" }, 207 { }, 208 }; 209 210 static struct platform_driver oppanel_driver = { 211 .driver = { 212 .name = "powernv-op-panel", 213 .of_match_table = oppanel_match, 214 }, 215 .probe = oppanel_probe, 216 .remove = oppanel_remove, 217 }; 218 219 module_platform_driver(oppanel_driver); 220 221 MODULE_DEVICE_TABLE(of, oppanel_match); 222 MODULE_LICENSE("GPL v2"); 223 MODULE_DESCRIPTION("PowerNV Operator Panel LCD Display Driver"); 224 MODULE_AUTHOR("Suraj Jitindar Singh <sjitindarsingh@gmail.com>"); 225