drivers/misc/bcm-vk/bcm_vk_tty.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Copyright 2018-2020 Broadcom.
   4  */
   5
   6 #include <linux/tty.h>
   7 #include <linux/tty_driver.h>
   8 #include <linux/tty_flip.h>
   9
  10 #include "bcm_vk.h"
  11
  12 /* TTYVK base offset is 0x30000 into BAR1 */
  13 #define BAR1_TTYVK_BASE_OFFSET  0x300000
  14 /* Each TTYVK channel (TO or FROM) is 0x10000 */
  15 #define BAR1_TTYVK_CHAN_OFFSET  0x100000
  16 /* Each TTYVK channel has TO and FROM, hence the * 2 */
  17 #define BAR1_TTYVK_BASE(index)  (BAR1_TTYVK_BASE_OFFSET + \
  18                                  ((index) * BAR1_TTYVK_CHAN_OFFSET * 2))
  19 /* TO TTYVK channel base comes before FROM for each index */
  20 #define TO_TTYK_BASE(index)     BAR1_TTYVK_BASE(index)
  21 #define FROM_TTYK_BASE(index)   (BAR1_TTYVK_BASE(index) + \
  22                                  BAR1_TTYVK_CHAN_OFFSET)
  23
  24 struct bcm_vk_tty_chan {
  25         u32 reserved;
  26         u32 size;
  27         u32 wr;
  28         u32 rd;
  29         u32 *data;
  30 };
  31
  32 #define VK_BAR_CHAN(v, DIR, e)  ((v)->DIR##_offset \
  33                                  + offsetof(struct bcm_vk_tty_chan, e))
  34 #define VK_BAR_CHAN_SIZE(v, DIR)        VK_BAR_CHAN(v, DIR, size)
  35 #define VK_BAR_CHAN_WR(v, DIR)          VK_BAR_CHAN(v, DIR, wr)
  36 #define VK_BAR_CHAN_RD(v, DIR)          VK_BAR_CHAN(v, DIR, rd)
  37 #define VK_BAR_CHAN_DATA(v, DIR, off)   (VK_BAR_CHAN(v, DIR, data) + (off))
  38
  39 #define VK_BAR0_REGSEG_TTY_DB_OFFSET    0x86c
  40
  41 /* Poll every 1/10 of second - temp hack till we use MSI interrupt */
  42 #define SERIAL_TIMER_VALUE (HZ / 10)
  43
  44 static void bcm_vk_tty_poll(struct timer_list *t)
  45 {
  46         struct bcm_vk *vk = from_timer(vk, t, serial_timer);
  47
  48         queue_work(vk->tty_wq_thread, &vk->tty_wq_work);
  49         mod_timer(&vk->serial_timer, jiffies + SERIAL_TIMER_VALUE);
  50 }
  51
  52 irqreturn_t bcm_vk_tty_irqhandler(int irq, void *dev_id)
  53 {
  54         struct bcm_vk *vk = dev_id;
  55
  56         queue_work(vk->tty_wq_thread, &vk->tty_wq_work);
  57
  58         return IRQ_HANDLED;
  59 }
  60
  61 static void bcm_vk_tty_wq_handler(struct work_struct *work)
  62 {
  63         struct bcm_vk *vk = container_of(work, struct bcm_vk, tty_wq_work);
  64         struct bcm_vk_tty *vktty;
  65         int card_status;
  66         int count;
  67         int i;
  68         int wr;
  69         u8 c;
  70
  71         card_status = vkread32(vk, BAR_0, BAR_CARD_STATUS);
  72         if (BCM_VK_INTF_IS_DOWN(card_status))
  73                 return;
  74
  75         for (i = 0; i < BCM_VK_NUM_TTY; i++) {
  76                 count = 0;
  77                 /* Check the card status that the tty channel is ready */
  78                 if ((card_status & BIT(i)) == 0)
  79                         continue;
  80
  81                 vktty = &vk->tty[i];
  82
  83                 /* Don't increment read index if tty app is closed */
  84                 if (!vktty->is_opened)
  85                         continue;
  86
  87                 /* Fetch the wr offset in buffer from VK */
  88                 wr = vkread32(vk, BAR_1, VK_BAR_CHAN_WR(vktty, from));
  89
  90                 /* safe to ignore until bar read gives proper size */
  91                 if (vktty->from_size == 0)
  92                         continue;
  93
  94                 if (wr >= vktty->from_size) {
  95                         dev_err(&vk->pdev->dev,
  96                                 "ERROR: wq handler ttyVK%d wr:0x%x > 0x%x\n",
  97                                 i, wr, vktty->from_size);
  98                         /* Need to signal and close device in this case */
  99                         continue;
 100                 }
 101
 102                 /*
 103                  * Simple read of circular buffer and
 104                  * insert into tty flip buffer
 105                  */
 106                 while (vk->tty[i].rd != wr) {
 107                         c = vkread8(vk, BAR_1,
 108                                     VK_BAR_CHAN_DATA(vktty, from, vktty->rd));
 109                         vktty->rd++;
 110                         if (vktty->rd >= vktty->from_size)
 111                                 vktty->rd = 0;
 112                         tty_insert_flip_char(&vktty->port, c, TTY_NORMAL);
 113                         count++;
 114                 }
 115
 116                 if (count) {
 117                         tty_flip_buffer_push(&vktty->port);
 118
 119                         /* Update read offset from shadow register to card */
 120                         vkwrite32(vk, vktty->rd, BAR_1,
 121                                   VK_BAR_CHAN_RD(vktty, from));
 122                 }
 123         }
 124 }
 125
 126 static int bcm_vk_tty_open(struct tty_struct *tty, struct file *file)
 127 {
 128         int card_status;
 129         struct bcm_vk *vk;
 130         struct bcm_vk_tty *vktty;
 131         int index;
 132
 133         /* initialize the pointer in case something fails */
 134         tty->driver_data = NULL;
 135
 136         vk = (struct bcm_vk *)dev_get_drvdata(tty->dev);
 137         index = tty->index;
 138
 139         if (index >= BCM_VK_NUM_TTY)
 140                 return -EINVAL;
 141
 142         vktty = &vk->tty[index];
 143
 144         vktty->pid = task_pid_nr(current);
 145         vktty->to_offset = TO_TTYK_BASE(index);
 146         vktty->from_offset = FROM_TTYK_BASE(index);
 147
 148         /* Do not allow tty device to be opened if tty on card not ready */
 149         card_status = vkread32(vk, BAR_0, BAR_CARD_STATUS);
 150         if (BCM_VK_INTF_IS_DOWN(card_status) || ((card_status & BIT(index)) == 0))
 151                 return -EBUSY;
 152
 153         /*
 154          * Get shadow registers of the buffer sizes and the "to" write offset
 155          * and "from" read offset
 156          */
 157         vktty->to_size = vkread32(vk, BAR_1, VK_BAR_CHAN_SIZE(vktty, to));
 158         vktty->wr = vkread32(vk, BAR_1,  VK_BAR_CHAN_WR(vktty, to));
 159         vktty->from_size = vkread32(vk, BAR_1, VK_BAR_CHAN_SIZE(vktty, from));
 160         vktty->rd = vkread32(vk, BAR_1,  VK_BAR_CHAN_RD(vktty, from));
 161         vktty->is_opened = true;
 162
 163         if (tty->count == 1 && !vktty->irq_enabled) {
 164                 timer_setup(&vk->serial_timer, bcm_vk_tty_poll, 0);
 165                 mod_timer(&vk->serial_timer, jiffies + SERIAL_TIMER_VALUE);
 166         }
 167         return 0;
 168 }
 169
 170 static void bcm_vk_tty_close(struct tty_struct *tty, struct file *file)
 171 {
 172         struct bcm_vk *vk = dev_get_drvdata(tty->dev);
 173
 174         if (tty->index >= BCM_VK_NUM_TTY)
 175                 return;
 176
 177         vk->tty[tty->index].is_opened = false;
 178
 179         if (tty->count == 1)
 180                 del_timer_sync(&vk->serial_timer);
 181 }
 182
 183 static void bcm_vk_tty_doorbell(struct bcm_vk *vk, u32 db_val)
 184 {
 185         vkwrite32(vk, db_val, BAR_0,
 186                   VK_BAR0_REGSEG_DB_BASE + VK_BAR0_REGSEG_TTY_DB_OFFSET);
 187 }
 188
 189 static ssize_t bcm_vk_tty_write(struct tty_struct *tty, const u8 *buffer,
 190                                 size_t count)
 191 {
 192         int index;
 193         struct bcm_vk *vk;
 194         struct bcm_vk_tty *vktty;
 195         size_t i;
 196
 197         index = tty->index;
 198         vk = dev_get_drvdata(tty->dev);
 199         vktty = &vk->tty[index];
 200
 201         /* Simple write each byte to circular buffer */
 202         for (i = 0; i < count; i++) {
 203                 vkwrite8(vk, buffer[i], BAR_1,
 204                          VK_BAR_CHAN_DATA(vktty, to, vktty->wr));
 205                 vktty->wr++;
 206                 if (vktty->wr >= vktty->to_size)
 207                         vktty->wr = 0;
 208         }
 209         /* Update write offset from shadow register to card */
 210         vkwrite32(vk, vktty->wr, BAR_1, VK_BAR_CHAN_WR(vktty, to));
 211         bcm_vk_tty_doorbell(vk, 0);
 212
 213         return count;
 214 }
 215
 216 static unsigned int bcm_vk_tty_write_room(struct tty_struct *tty)
 217 {
 218         struct bcm_vk *vk = dev_get_drvdata(tty->dev);
 219
 220         return vk->tty[tty->index].to_size - 1;
 221 }
 222
 223 static const struct tty_operations serial_ops = {
 224         .open = bcm_vk_tty_open,
 225         .close = bcm_vk_tty_close,
 226         .write = bcm_vk_tty_write,
 227         .write_room = bcm_vk_tty_write_room,
 228 };
 229
 230 int bcm_vk_tty_init(struct bcm_vk *vk, char *name)
 231 {
 232         int i;
 233         int err;
 234         struct tty_driver *tty_drv;
 235         struct device *dev = &vk->pdev->dev;
 236
 237         tty_drv = tty_alloc_driver
 238                                 (BCM_VK_NUM_TTY,
 239                                  TTY_DRIVER_REAL_RAW | TTY_DRIVER_DYNAMIC_DEV);
 240         if (IS_ERR(tty_drv))
 241                 return PTR_ERR(tty_drv);
 242
 243         /* Save struct tty_driver for uninstalling the device */
 244         vk->tty_drv = tty_drv;
 245
 246         /* initialize the tty driver */
 247         tty_drv->driver_name = KBUILD_MODNAME;
 248         tty_drv->name = kstrdup(name, GFP_KERNEL);
 249         if (!tty_drv->name) {
 250                 err = -ENOMEM;
 251                 goto err_tty_driver_kref_put;
 252         }
 253         tty_drv->type = TTY_DRIVER_TYPE_SERIAL;
 254         tty_drv->subtype = SERIAL_TYPE_NORMAL;
 255         tty_drv->init_termios = tty_std_termios;
 256         tty_set_operations(tty_drv, &serial_ops);
 257
 258         /* register the tty driver */
 259         err = tty_register_driver(tty_drv);
 260         if (err) {
 261                 dev_err(dev, "tty_register_driver failed\n");
 262                 goto err_kfree_tty_name;
 263         }
 264
 265         for (i = 0; i < BCM_VK_NUM_TTY; i++) {
 266                 struct device *tty_dev;
 267
 268                 tty_port_init(&vk->tty[i].port);
 269                 tty_dev = tty_port_register_device_attr(&vk->tty[i].port,
 270                                                         tty_drv, i, dev, vk,
 271                                                         NULL);
 272                 if (IS_ERR(tty_dev)) {
 273                         err = PTR_ERR(tty_dev);
 274                         goto unwind;
 275                 }
 276                 vk->tty[i].is_opened = false;
 277         }
 278
 279         INIT_WORK(&vk->tty_wq_work, bcm_vk_tty_wq_handler);
 280         vk->tty_wq_thread = create_singlethread_workqueue("tty");
 281         if (!vk->tty_wq_thread) {
 282                 dev_err(dev, "Fail to create tty workqueue thread\n");
 283                 err = -ENOMEM;
 284                 goto unwind;
 285         }
 286         return 0;
 287
 288 unwind:
 289         while (--i >= 0)
 290                 tty_port_unregister_device(&vk->tty[i].port, tty_drv, i);
 291         tty_unregister_driver(tty_drv);
 292
 293 err_kfree_tty_name:
 294         kfree(tty_drv->name);
 295         tty_drv->name = NULL;
 296
 297 err_tty_driver_kref_put:
 298         tty_driver_kref_put(tty_drv);
 299
 300         return err;
 301 }
 302
 303 void bcm_vk_tty_exit(struct bcm_vk *vk)
 304 {
 305         int i;
 306
 307         del_timer_sync(&vk->serial_timer);
 308         for (i = 0; i < BCM_VK_NUM_TTY; ++i) {
 309                 tty_port_unregister_device(&vk->tty[i].port,
 310                                            vk->tty_drv,
 311                                            i);
 312                 tty_port_destroy(&vk->tty[i].port);
 313         }
 314         tty_unregister_driver(vk->tty_drv);
 315
 316         kfree(vk->tty_drv->name);
 317         vk->tty_drv->name = NULL;
 318
 319         tty_driver_kref_put(vk->tty_drv);
 320 }
 321
 322 void bcm_vk_tty_terminate_tty_user(struct bcm_vk *vk)
 323 {
 324         struct bcm_vk_tty *vktty;
 325         int i;
 326
 327         for (i = 0; i < BCM_VK_NUM_TTY; ++i) {
 328                 vktty = &vk->tty[i];
 329                 if (vktty->pid)
 330                         kill_pid(find_vpid(vktty->pid), SIGKILL, 1);
 331         }
 332 }
 333
 334 void bcm_vk_tty_wq_exit(struct bcm_vk *vk)
 335 {
 336         cancel_work_sync(&vk->tty_wq_work);
 337         destroy_workqueue(vk->tty_wq_thread);
 338 }