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
24struct 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
44static void bcm_vk_tty_poll(struct timer_list *t)
45{
46 struct bcm_vk *vk = timer_container_of(vk, t, serial_timer);
47
48 queue_work(wq: vk->tty_wq_thread, work: &vk->tty_wq_work);
49 mod_timer(timer: &vk->serial_timer, expires: jiffies + SERIAL_TIMER_VALUE);
50}
51
52irqreturn_t bcm_vk_tty_irqhandler(int irq, void *dev_id)
53{
54 struct bcm_vk *vk = dev_id;
55
56 queue_work(wq: vk->tty_wq_thread, work: &vk->tty_wq_work);
57
58 return IRQ_HANDLED;
59}
60
61static 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: 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: 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: 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(port: &vktty->port, ch: c, TTY_NORMAL);
113 count++;
114 }
115
116 if (count) {
117 tty_flip_buffer_push(port: &vktty->port);
118
119 /* Update read offset from shadow register to card */
120 vkwrite32(vk, value: vktty->rd, bar: BAR_1,
121 VK_BAR_CHAN_RD(vktty, from));
122 }
123 }
124}
125
126static 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(dev: 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: 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: BAR_1, VK_BAR_CHAN_SIZE(vktty, to));
158 vktty->wr = vkread32(vk, bar: BAR_1, VK_BAR_CHAN_WR(vktty, to));
159 vktty->from_size = vkread32(vk, bar: BAR_1, VK_BAR_CHAN_SIZE(vktty, from));
160 vktty->rd = vkread32(vk, bar: 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(timer: &vk->serial_timer, expires: jiffies + SERIAL_TIMER_VALUE);
166 }
167 return 0;
168}
169
170static void bcm_vk_tty_close(struct tty_struct *tty, struct file *file)
171{
172 struct bcm_vk *vk = dev_get_drvdata(dev: 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 timer_delete_sync(timer: &vk->serial_timer);
181}
182
183static void bcm_vk_tty_doorbell(struct bcm_vk *vk, u32 db_val)
184{
185 vkwrite32(vk, value: db_val, bar: BAR_0,
186 VK_BAR0_REGSEG_DB_BASE + VK_BAR0_REGSEG_TTY_DB_OFFSET);
187}
188
189static 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(dev: 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, value: buffer[i], bar: 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, value: vktty->wr, bar: BAR_1, VK_BAR_CHAN_WR(vktty, to));
211 bcm_vk_tty_doorbell(vk, db_val: 0);
212
213 return count;
214}
215
216static unsigned int bcm_vk_tty_write_room(struct tty_struct *tty)
217{
218 struct bcm_vk *vk = dev_get_drvdata(dev: tty->dev);
219
220 return vk->tty[tty->index].to_size - 1;
221}
222
223static 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
230int 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(ptr: tty_drv))
241 return PTR_ERR(ptr: 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(s: 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(driver: tty_drv, op: &serial_ops);
257
258 /* register the tty driver */
259 err = tty_register_driver(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(port: &vk->tty[i].port);
269 tty_dev = tty_port_register_device_attr(port: &vk->tty[i].port,
270 driver: tty_drv, index: i, device: dev, drvdata: vk,
271 NULL);
272 if (IS_ERR(ptr: tty_dev)) {
273 err = PTR_ERR(ptr: 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
288unwind:
289 while (--i >= 0)
290 tty_port_unregister_device(port: &vk->tty[i].port, driver: tty_drv, index: i);
291 tty_unregister_driver(driver: tty_drv);
292
293err_kfree_tty_name:
294 kfree(objp: tty_drv->name);
295 tty_drv->name = NULL;
296
297err_tty_driver_kref_put:
298 tty_driver_kref_put(driver: tty_drv);
299
300 return err;
301}
302
303void bcm_vk_tty_exit(struct bcm_vk *vk)
304{
305 int i;
306
307 timer_delete_sync(timer: &vk->serial_timer);
308 for (i = 0; i < BCM_VK_NUM_TTY; ++i) {
309 tty_port_unregister_device(port: &vk->tty[i].port,
310 driver: vk->tty_drv,
311 index: i);
312 tty_port_destroy(port: &vk->tty[i].port);
313 }
314 tty_unregister_driver(driver: vk->tty_drv);
315
316 kfree(objp: vk->tty_drv->name);
317 vk->tty_drv->name = NULL;
318
319 tty_driver_kref_put(driver: vk->tty_drv);
320}
321
322void 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(pid: find_vpid(nr: vktty->pid), SIGKILL, priv: 1);
331 }
332}
333
334void bcm_vk_tty_wq_exit(struct bcm_vk *vk)
335{
336 cancel_work_sync(work: &vk->tty_wq_work);
337 destroy_workqueue(wq: vk->tty_wq_thread);
338}
339

source code of linux/drivers/misc/bcm-vk/bcm_vk_tty.c