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
to_hdm(struct most_interface * iface)47 static inline struct hdm_i2c *to_hdm(struct most_interface *iface)
48 {
49 return container_of(iface, struct hdm_i2c, most_iface);
50 }
51
52 static irqreturn_t most_irq_handler(int, void *);
53 static void pending_rx_work(struct work_struct *);
54
55 /**
56 * configure_channel - called from MOST core to configure a channel
57 * @most_iface: interface the channel belongs to
58 * @ch_idx: channel to be configured
59 * @channel_config: structure that holds the configuration information
60 *
61 * Return 0 on success, negative on failure.
62 *
63 * Receives configuration information from MOST core and initialize the
64 * corresponding channel.
65 */
configure_channel(struct most_interface * most_iface,int ch_idx,struct most_channel_config * channel_config)66 static int configure_channel(struct most_interface *most_iface,
67 int ch_idx,
68 struct most_channel_config *channel_config)
69 {
70 int ret;
71 struct hdm_i2c *dev = to_hdm(most_iface);
72 unsigned int delay, pr;
73
74 BUG_ON(ch_idx < 0 || ch_idx >= NUM_CHANNELS);
75
76 if (channel_config->data_type != MOST_CH_CONTROL) {
77 pr_err("bad data type for channel %d\n", ch_idx);
78 return -EPERM;
79 }
80
81 if (channel_config->direction != dev->capabilities[ch_idx].direction) {
82 pr_err("bad direction for channel %d\n", ch_idx);
83 return -EPERM;
84 }
85
86 if (channel_config->direction == MOST_CH_RX) {
87 if (!polling_rate) {
88 if (dev->client->irq <= 0) {
89 pr_err("bad irq: %d\n", dev->client->irq);
90 return -ENOENT;
91 }
92 dev->rx.int_disabled = false;
93 ret = request_irq(dev->client->irq, most_irq_handler, 0,
94 dev->client->name, dev);
95 if (ret) {
96 pr_err("request_irq(%d) failed: %d\n",
97 dev->client->irq, ret);
98 return ret;
99 }
100 } else {
101 delay = msecs_to_jiffies(MSEC_PER_SEC / polling_rate);
102 dev->rx.delay = delay ? delay : 1;
103 pr = MSEC_PER_SEC / jiffies_to_msecs(dev->rx.delay);
104 pr_info("polling rate is %u Hz\n", pr);
105 }
106 }
107
108 return 0;
109 }
110
111 /**
112 * enqueue - called from MOST core to enqueue a buffer for data transfer
113 * @most_iface: intended interface
114 * @ch_idx: ID of the channel the buffer is intended for
115 * @mbo: pointer to the buffer object
116 *
117 * Return 0 on success, negative on failure.
118 *
119 * Transmit the data over I2C if it is a "write" request or push the buffer into
120 * list if it is an "read" request
121 */
enqueue(struct most_interface * most_iface,int ch_idx,struct mbo * mbo)122 static int enqueue(struct most_interface *most_iface,
123 int ch_idx, struct mbo *mbo)
124 {
125 struct hdm_i2c *dev = to_hdm(most_iface);
126 int ret;
127
128 BUG_ON(ch_idx < 0 || ch_idx >= NUM_CHANNELS);
129
130 if (ch_idx == CH_RX) {
131 /* RX */
132 if (!polling_rate)
133 disable_irq(dev->client->irq);
134 cancel_delayed_work_sync(&dev->rx.dwork);
135 list_add_tail(&mbo->list, &dev->rx.list);
136 if (dev->rx.int_disabled || polling_rate)
137 pending_rx_work(&dev->rx.dwork.work);
138 if (!polling_rate)
139 enable_irq(dev->client->irq);
140 } else {
141 /* TX */
142 ret = i2c_master_send(dev->client, mbo->virt_address,
143 mbo->buffer_length);
144 if (ret <= 0) {
145 mbo->processed_length = 0;
146 mbo->status = MBO_E_INVAL;
147 } else {
148 mbo->processed_length = mbo->buffer_length;
149 mbo->status = MBO_SUCCESS;
150 }
151 mbo->complete(mbo);
152 }
153
154 return 0;
155 }
156
157 /**
158 * poison_channel - called from MOST core to poison buffers of a channel
159 * @most_iface: pointer to the interface the channel to be poisoned belongs to
160 * @ch_idx: corresponding channel ID
161 *
162 * Return 0 on success, negative on failure.
163 *
164 * If channel direction is RX, complete the buffers in list with
165 * status MBO_E_CLOSE
166 */
poison_channel(struct most_interface * most_iface,int ch_idx)167 static int poison_channel(struct most_interface *most_iface,
168 int ch_idx)
169 {
170 struct hdm_i2c *dev = to_hdm(most_iface);
171 struct mbo *mbo;
172
173 BUG_ON(ch_idx < 0 || ch_idx >= NUM_CHANNELS);
174
175 if (ch_idx == CH_RX) {
176 if (!polling_rate)
177 free_irq(dev->client->irq, dev);
178 cancel_delayed_work_sync(&dev->rx.dwork);
179
180 while (!list_empty(&dev->rx.list)) {
181 mbo = list_first_mbo(&dev->rx.list);
182 list_del(&mbo->list);
183
184 mbo->processed_length = 0;
185 mbo->status = MBO_E_CLOSE;
186 mbo->complete(mbo);
187 }
188 }
189
190 return 0;
191 }
192
do_rx_work(struct hdm_i2c * dev)193 static void do_rx_work(struct hdm_i2c *dev)
194 {
195 struct mbo *mbo;
196 unsigned char msg[MAX_BUF_SIZE_CONTROL];
197 int ret;
198 u16 pml, data_size;
199
200 /* Read PML (2 bytes) */
201 ret = i2c_master_recv(dev->client, msg, 2);
202 if (ret <= 0) {
203 pr_err("Failed to receive PML\n");
204 return;
205 }
206
207 pml = (msg[0] << 8) | msg[1];
208 if (!pml)
209 return;
210
211 data_size = pml + 2;
212
213 /* Read the whole message, including PML */
214 ret = i2c_master_recv(dev->client, msg, data_size);
215 if (ret <= 0) {
216 pr_err("Failed to receive a Port Message\n");
217 return;
218 }
219
220 mbo = list_first_mbo(&dev->rx.list);
221 list_del(&mbo->list);
222
223 mbo->processed_length = min(data_size, mbo->buffer_length);
224 memcpy(mbo->virt_address, msg, mbo->processed_length);
225 mbo->status = MBO_SUCCESS;
226 mbo->complete(mbo);
227 }
228
229 /**
230 * pending_rx_work - Read pending messages through I2C
231 * @work: definition of this work item
232 *
233 * Invoked by the Interrupt Service Routine, most_irq_handler()
234 */
pending_rx_work(struct work_struct * work)235 static void pending_rx_work(struct work_struct *work)
236 {
237 struct hdm_i2c *dev = container_of(work, struct hdm_i2c, rx.dwork.work);
238
239 if (list_empty(&dev->rx.list))
240 return;
241
242 do_rx_work(dev);
243
244 if (polling_rate) {
245 schedule_delayed_work(&dev->rx.dwork, dev->rx.delay);
246 } else {
247 dev->rx.int_disabled = false;
248 enable_irq(dev->client->irq);
249 }
250 }
251
252 /*
253 * most_irq_handler - Interrupt Service Routine
254 * @irq: irq number
255 * @_dev: private data
256 *
257 * Schedules a delayed work
258 *
259 * By default the interrupt line behavior is Active Low. Once an interrupt is
260 * generated by the device, until driver clears the interrupt (by reading
261 * the PMP message), device keeps the interrupt line in low state. Since i2c
262 * read is done in work queue, the interrupt line must be disabled temporarily
263 * to avoid ISR being called repeatedly. Re-enable the interrupt in workqueue,
264 * after reading the message.
265 *
266 * Note: If we use the interrupt line in Falling edge mode, there is a
267 * possibility to miss interrupts when ISR is getting executed.
268 *
269 */
most_irq_handler(int irq,void * _dev)270 static irqreturn_t most_irq_handler(int irq, void *_dev)
271 {
272 struct hdm_i2c *dev = _dev;
273
274 disable_irq_nosync(irq);
275 dev->rx.int_disabled = true;
276 schedule_delayed_work(&dev->rx.dwork, 0);
277
278 return IRQ_HANDLED;
279 }
280
281 /*
282 * i2c_probe - i2c probe handler
283 * @client: i2c client device structure
284 * @id: i2c client device id
285 *
286 * Return 0 on success, negative on failure.
287 *
288 * Register the i2c client device as a MOST interface
289 */
i2c_probe(struct i2c_client * client)290 static int i2c_probe(struct i2c_client *client)
291 {
292 struct hdm_i2c *dev;
293 int ret, i;
294
295 dev = kzalloc(sizeof(*dev), GFP_KERNEL);
296 if (!dev)
297 return -ENOMEM;
298
299 /* ID format: i2c-<bus>-<address> */
300 snprintf(dev->name, sizeof(dev->name), "i2c-%d-%04x",
301 client->adapter->nr, client->addr);
302
303 for (i = 0; i < NUM_CHANNELS; i++) {
304 dev->capabilities[i].data_type = MOST_CH_CONTROL;
305 dev->capabilities[i].num_buffers_packet = MAX_BUFFERS_CONTROL;
306 dev->capabilities[i].buffer_size_packet = MAX_BUF_SIZE_CONTROL;
307 }
308 dev->capabilities[CH_RX].direction = MOST_CH_RX;
309 dev->capabilities[CH_RX].name_suffix = "rx";
310 dev->capabilities[CH_TX].direction = MOST_CH_TX;
311 dev->capabilities[CH_TX].name_suffix = "tx";
312
313 dev->most_iface.interface = ITYPE_I2C;
314 dev->most_iface.description = dev->name;
315 dev->most_iface.num_channels = NUM_CHANNELS;
316 dev->most_iface.channel_vector = dev->capabilities;
317 dev->most_iface.configure = configure_channel;
318 dev->most_iface.enqueue = enqueue;
319 dev->most_iface.poison_channel = poison_channel;
320
321 INIT_LIST_HEAD(&dev->rx.list);
322
323 INIT_DELAYED_WORK(&dev->rx.dwork, pending_rx_work);
324
325 dev->client = client;
326 i2c_set_clientdata(client, dev);
327
328 ret = most_register_interface(&dev->most_iface);
329 if (ret) {
330 pr_err("Failed to register i2c as a MOST interface\n");
331 kfree(dev);
332 return ret;
333 }
334
335 return 0;
336 }
337
338 /*
339 * i2c_remove - i2c remove handler
340 * @client: i2c client device structure
341 *
342 * Return 0 on success.
343 *
344 * Unregister the i2c client device as a MOST interface
345 */
i2c_remove(struct i2c_client * client)346 static void i2c_remove(struct i2c_client *client)
347 {
348 struct hdm_i2c *dev = i2c_get_clientdata(client);
349
350 most_deregister_interface(&dev->most_iface);
351 kfree(dev);
352 }
353
354 static const struct i2c_device_id i2c_id[] = {
355 { "most_i2c", 0 },
356 { }, /* Terminating entry */
357 };
358
359 MODULE_DEVICE_TABLE(i2c, i2c_id);
360
361 static struct i2c_driver i2c_driver = {
362 .driver = {
363 .name = "hdm_i2c",
364 },
365 .probe = i2c_probe,
366 .remove = i2c_remove,
367 .id_table = i2c_id,
368 };
369
370 module_i2c_driver(i2c_driver);
371
372 MODULE_AUTHOR("Andrey Shvetsov <andrey.shvetsov@k2l.de>");
373 MODULE_DESCRIPTION("I2C Hardware Dependent Module");
374 MODULE_LICENSE("GPL");
375
