drivers/char/powernv-op-panel.c

   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
  31 static DEFINE_MUTEX(oppanel_mutex);
  32
  33 static u32              num_lines, oppanel_size;
  34 static oppanel_line_t   *oppanel_lines;
  35 static char             *oppanel_data;
  36
  37 static 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
  42 static 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
  49 static 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
  87 static 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
 113 static 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
 122 static int oppanel_release(struct inode *inode, struct file *filp)
 123 {
 124         mutex_unlock(&oppanel_mutex);
 125         return 0;
 126 }
 127
 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
 135 };
 136
 137 static struct miscdevice oppanel_dev = {
 138         .minor          = MISC_DYNAMIC_MINOR,
 139         .name           = "op_panel",
 140         .fops           = &oppanel_fops
 141 };
 142
 143 static 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
 189 free_oppanel:
 190         kfree(oppanel_lines);
 191 free_oppanel_data:
 192         kfree(oppanel_data);
 193         return rc;
 194 }
 195
 196 static 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
 204 static const struct of_device_id oppanel_match[] = {
 205         { .compatible = "ibm,opal-oppanel" },
 206         { },
 207 };
 208
 209 static 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
 218 module_platform_driver(oppanel_driver);
 219
 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>");