1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * i2c.c - Hardware Dependent Module for I2C Interface
4 *
5 * Copyright (C) 2013-2015, Microchip Technology Germany II GmbH & Co. KG
6 */
7
8 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
9
10 #include <linux/init.h>
11 #include <linux/module.h>
12 #include <linux/slab.h>
13 #include <linux/i2c.h>
14 #include <linux/interrupt.h>
15 #include <linux/err.h>
16 #include <linux/most.h>
17
18 enum { CH_RX, CH_TX, NUM_CHANNELS };
19
20 #define MAX_BUFFERS_CONTROL 32
21 #define MAX_BUF_SIZE_CONTROL 256
22
23 /**
24 * list_first_mbo - get the first mbo from a list
25 * @ptr: the list head to take the mbo from.
26 */
27 #define list_first_mbo(ptr) \
28 list_first_entry(ptr, struct mbo, list)
29
30 static unsigned int polling_rate;
31 module_param(polling_rate, uint, 0644);
32 MODULE_PARM_DESC(polling_rate, "Polling rate [Hz]. Default = 0 (use IRQ)");
33
34 struct hdm_i2c {
35 struct most_interface most_iface;
36 struct most_channel_capability capabilities[NUM_CHANNELS];
37 struct i2c_client *client;
38 struct rx {
39 struct delayed_work dwork;
40 struct list_head list;
41 bool int_disabled;
42 unsigned int delay;
43 } rx;
44 char name[64];
45 };
46
47 #define to_hdm(iface) container_of(iface, struct hdm_i2c, most_iface)
48
49 static irqreturn_t most_irq_handler(int, void *);
50 static void pending_rx_work(struct work_struct *);
51
52 /**
53 * configure_channel - called from MOST core to configure a channel
54 * @most_iface: interface the channel belongs to
55 * @ch_idx: channel to be configured
56 * @channel_config: structure that holds the configuration information
57 *
58 * Return 0 on success, negative on failure.
59 *
60 * Receives configuration information from MOST core and initialize the
61 * corresponding channel.
62 */
configure_channel(struct most_interface * most_iface,int ch_idx,struct most_channel_config * channel_config)63 static int configure_channel(struct most_interface *most_iface,
64 int ch_idx,
65 struct most_channel_config *channel_config)
66 {
67 int ret;
68 struct hdm_i2c *dev = to_hdm(most_iface);
69 unsigned int delay, pr;
70
71 BUG_ON(ch_idx < 0 || ch_idx >= NUM_CHANNELS);
72
73 if (channel_config->data_type != MOST_CH_CONTROL) {
74 pr_err("bad data type for channel %d\n", ch_idx);
75 return -EPERM;
76 }
77
78 if (channel_config->direction != dev->capabilities[ch_idx].direction) {
79 pr_err("bad direction for channel %d\n", ch_idx);
80 return -EPERM;
81 }
82
83 if (channel_config->direction == MOST_CH_RX) {
84 if (!polling_rate) {
85 if (dev->client->irq <= 0) {
86 pr_err("bad irq: %d\n", dev->client->irq);
87 return -ENOENT;
88 }
89 dev->rx.int_disabled = false;
90 ret = request_irq(dev->client->irq, most_irq_handler, 0,
91 dev->client->name, dev);
92 if (ret) {
93 pr_err("request_irq(%d) failed: %d\n",
94 dev->client->irq, ret);
95 return ret;
96 }
97 } else {
98 delay = msecs_to_jiffies(MSEC_PER_SEC / polling_rate);
99 dev->rx.delay = delay ? delay : 1;
100 pr = MSEC_PER_SEC / jiffies_to_msecs(dev->rx.delay);
101 pr_info("polling rate is %u Hz\n", pr);
102 }
103 }
104
105 return 0;
106 }
107
108 /**
109 * enqueue - called from MOST core to enqueue a buffer for data transfer
110 * @most_iface: intended interface
111 * @ch_idx: ID of the channel the buffer is intended for
112 * @mbo: pointer to the buffer object
113 *
114 * Return 0 on success, negative on failure.
115 *
116 * Transmit the data over I2C if it is a "write" request or push the buffer into
117 * list if it is an "read" request
118 */
enqueue(struct most_interface * most_iface,int ch_idx,struct mbo * mbo)119 static int enqueue(struct most_interface *most_iface,
120 int ch_idx, struct mbo *mbo)
121 {
122 struct hdm_i2c *dev = to_hdm(most_iface);
123 int ret;
124
125 BUG_ON(ch_idx < 0 || ch_idx >= NUM_CHANNELS);
126
127 if (ch_idx == CH_RX) {
128 /* RX */
129 if (!polling_rate)
130 disable_irq(dev->client->irq);
131 cancel_delayed_work_sync(&dev->rx.dwork);
132 list_add_tail(&mbo->list, &dev->rx.list);
133 if (dev->rx.int_disabled || polling_rate)
134 pending_rx_work(&dev->rx.dwork.work);
135 if (!polling_rate)
136 enable_irq(dev->client->irq);
137 } else {
138 /* TX */
139 ret = i2c_master_send(dev->client, mbo->virt_address,
140 mbo->buffer_length);
141 if (ret <= 0) {
142 mbo->processed_length = 0;
143 mbo->status = MBO_E_INVAL;
144 } else {
145 mbo->processed_length = mbo->buffer_length;
146 mbo->status = MBO_SUCCESS;
147 }
148 mbo->complete(mbo);
149 }
150
151 return 0;
152 }
153
154 /**
155 * poison_channel - called from MOST core to poison buffers of a channel
156 * @most_iface: pointer to the interface the channel to be poisoned belongs to
157 * @ch_idx: corresponding channel ID
158 *
159 * Return 0 on success, negative on failure.
160 *
161 * If channel direction is RX, complete the buffers in list with
162 * status MBO_E_CLOSE
163 */
poison_channel(struct most_interface * most_iface,int ch_idx)164 static int poison_channel(struct most_interface *most_iface,
165 int ch_idx)
166 {
167 struct hdm_i2c *dev = to_hdm(most_iface);
168 struct mbo *mbo;
169
170 BUG_ON(ch_idx < 0 || ch_idx >= NUM_CHANNELS);
171
172 if (ch_idx == CH_RX) {
173 if (!polling_rate)
174 free_irq(dev->client->irq, dev);
175 cancel_delayed_work_sync(&dev->rx.dwork);
176
177 while (!list_empty(&dev->rx.list)) {
178 mbo = list_first_mbo(&dev->rx.list);
179 list_del(&mbo->list);
180
181 mbo->processed_length = 0;
182 mbo->status = MBO_E_CLOSE;
183 mbo->complete(mbo);
184 }
185 }
186
187 return 0;
188 }
189
do_rx_work(struct hdm_i2c * dev)190 static void do_rx_work(struct hdm_i2c *dev)
191 {
192 struct mbo *mbo;
193 unsigned char msg[MAX_BUF_SIZE_CONTROL];
194 int ret;
195 u16 pml, data_size;
196
197 /* Read PML (2 bytes) */
198 ret = i2c_master_recv(dev->client, msg, 2);
199 if (ret <= 0) {
200 pr_err("Failed to receive PML\n");
201 return;
202 }
203
204 pml = (msg[0] << 8) | msg[1];
205 if (!pml)
206 return;
207
208 data_size = pml + 2;
209
210 /* Read the whole message, including PML */
211 ret = i2c_master_recv(dev->client, msg, data_size);
212 if (ret <= 0) {
213 pr_err("Failed to receive a Port Message\n");
214 return;
215 }
216
217 mbo = list_first_mbo(&dev->rx.list);
218 list_del(&mbo->list);
219
220 mbo->processed_length = min(data_size, mbo->buffer_length);
221 memcpy(mbo->virt_address, msg, mbo->processed_length);
222 mbo->status = MBO_SUCCESS;
223 mbo->complete(mbo);
224 }
225
226 /**
227 * pending_rx_work - Read pending messages through I2C
228 * @work: definition of this work item
229 *
230 * Invoked by the Interrupt Service Routine, most_irq_handler()
231 */
pending_rx_work(struct work_struct * work)232 static void pending_rx_work(struct work_struct *work)
233 {
234 struct hdm_i2c *dev = container_of(work, struct hdm_i2c, rx.dwork.work);
235
236 if (list_empty(&dev->rx.list))
237 return;
238
239 do_rx_work(dev);
240
241 if (polling_rate) {
242 schedule_delayed_work(&dev->rx.dwork, dev->rx.delay);
243 } else {
244 dev->rx.int_disabled = false;
245 enable_irq(dev->client->irq);
246 }
247 }
248
249 /*
250 * most_irq_handler - Interrupt Service Routine
251 * @irq: irq number
252 * @_dev: private data
253 *
254 * Schedules a delayed work
255 *
256 * By default the interrupt line behavior is Active Low. Once an interrupt is
257 * generated by the device, until driver clears the interrupt (by reading
258 * the PMP message), device keeps the interrupt line in low state. Since i2c
259 * read is done in work queue, the interrupt line must be disabled temporarily
260 * to avoid ISR being called repeatedly. Re-enable the interrupt in workqueue,
261 * after reading the message.
262 *
263 * Note: If we use the interrupt line in Falling edge mode, there is a
264 * possibility to miss interrupts when ISR is getting executed.
265 *
266 */
most_irq_handler(int irq,void * _dev)267 static irqreturn_t most_irq_handler(int irq, void *_dev)
268 {
269 struct hdm_i2c *dev = _dev;
270
271 disable_irq_nosync(irq);
272 dev->rx.int_disabled = true;
273 schedule_delayed_work(&dev->rx.dwork, 0);
274
275 return IRQ_HANDLED;
276 }
277
278 /*
279 * i2c_probe - i2c probe handler
280 * @client: i2c client device structure
281 * @id: i2c client device id
282 *
283 * Return 0 on success, negative on failure.
284 *
285 * Register the i2c client device as a MOST interface
286 */
i2c_probe(struct i2c_client * client,const struct i2c_device_id * id)287 static int i2c_probe(struct i2c_client *client, const struct i2c_device_id *id)
288 {
289 struct hdm_i2c *dev;
290 int ret, i;
291
292 dev = kzalloc(sizeof(*dev), GFP_KERNEL);
293 if (!dev)
294 return -ENOMEM;
295
296 /* ID format: i2c-<bus>-<address> */
297 snprintf(dev->name, sizeof(dev->name), "i2c-%d-%04x",
298 client->adapter->nr, client->addr);
299
300 for (i = 0; i < NUM_CHANNELS; i++) {
301 dev->capabilities[i].data_type = MOST_CH_CONTROL;
302 dev->capabilities[i].num_buffers_packet = MAX_BUFFERS_CONTROL;
303 dev->capabilities[i].buffer_size_packet = MAX_BUF_SIZE_CONTROL;
304 }
305 dev->capabilities[CH_RX].direction = MOST_CH_RX;
306 dev->capabilities[CH_RX].name_suffix = "rx";
307 dev->capabilities[CH_TX].direction = MOST_CH_TX;
308 dev->capabilities[CH_TX].name_suffix = "tx";
309
310 dev->most_iface.interface = ITYPE_I2C;
311 dev->most_iface.description = dev->name;
312 dev->most_iface.num_channels = NUM_CHANNELS;
313 dev->most_iface.channel_vector = dev->capabilities;
314 dev->most_iface.configure = configure_channel;
315 dev->most_iface.enqueue = enqueue;
316 dev->most_iface.poison_channel = poison_channel;
317
318 INIT_LIST_HEAD(&dev->rx.list);
319
320 INIT_DELAYED_WORK(&dev->rx.dwork, pending_rx_work);
321
322 dev->client = client;
323 i2c_set_clientdata(client, dev);
324
325 ret = most_register_interface(&dev->most_iface);
326 if (ret) {
327 pr_err("Failed to register i2c as a MOST interface\n");
328 kfree(dev);
329 return ret;
330 }
331
332 return 0;
333 }
334
335 /*
336 * i2c_remove - i2c remove handler
337 * @client: i2c client device structure
338 *
339 * Return 0 on success.
340 *
341 * Unregister the i2c client device as a MOST interface
342 */
i2c_remove(struct i2c_client * client)343 static int i2c_remove(struct i2c_client *client)
344 {
345 struct hdm_i2c *dev = i2c_get_clientdata(client);
346
347 most_deregister_interface(&dev->most_iface);
348 kfree(dev);
349
350 return 0;
351 }
352
353 static const struct i2c_device_id i2c_id[] = {
354 { "most_i2c", 0 },
355 { }, /* Terminating entry */
356 };
357
358 MODULE_DEVICE_TABLE(i2c, i2c_id);
359
360 static struct i2c_driver i2c_driver = {
361 .driver = {
362 .name = "hdm_i2c",
363 },
364 .probe = i2c_probe,
365 .remove = i2c_remove,
366 .id_table = i2c_id,
367 };
368
369 module_i2c_driver(i2c_driver);
370
371 MODULE_AUTHOR("Andrey Shvetsov <andrey.shvetsov@k2l.de>");
372 MODULE_DESCRIPTION("I2C Hardware Dependent Module");
373 MODULE_LICENSE("GPL");
374