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 | 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 | */ |
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(iface: 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(irq: dev->client->irq, handler: most_irq_handler, flags: 0, |
94 | name: 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(j: 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 | */ |
122 | static int enqueue(struct most_interface *most_iface, |
123 | int ch_idx, struct mbo *mbo) |
124 | { |
125 | struct hdm_i2c *dev = to_hdm(iface: 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(irq: dev->client->irq); |
134 | cancel_delayed_work_sync(dwork: &dev->rx.dwork); |
135 | list_add_tail(new: &mbo->list, head: &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(irq: dev->client->irq); |
140 | } else { |
141 | /* TX */ |
142 | ret = i2c_master_send(client: dev->client, buf: mbo->virt_address, |
143 | count: 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 | */ |
167 | static int poison_channel(struct most_interface *most_iface, |
168 | int ch_idx) |
169 | { |
170 | struct hdm_i2c *dev = to_hdm(iface: 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(dwork: &dev->rx.dwork); |
179 | |
180 | while (!list_empty(head: &dev->rx.list)) { |
181 | mbo = list_first_mbo(&dev->rx.list); |
182 | list_del(entry: &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 | |
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(client: dev->client, buf: msg, count: 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(client: dev->client, buf: msg, count: 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(entry: &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 | */ |
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(head: &dev->rx.list)) |
240 | return; |
241 | |
242 | do_rx_work(dev); |
243 | |
244 | if (polling_rate) { |
245 | schedule_delayed_work(dwork: &dev->rx.dwork, delay: dev->rx.delay); |
246 | } else { |
247 | dev->rx.int_disabled = false; |
248 | enable_irq(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 | */ |
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(dwork: &dev->rx.dwork, delay: 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 | */ |
290 | static int i2c_probe(struct i2c_client *client) |
291 | { |
292 | struct hdm_i2c *dev; |
293 | int ret, i; |
294 | |
295 | dev = kzalloc(size: sizeof(*dev), GFP_KERNEL); |
296 | if (!dev) |
297 | return -ENOMEM; |
298 | |
299 | /* ID format: i2c-<bus>-<address> */ |
300 | snprintf(buf: dev->name, size: sizeof(dev->name), fmt: "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(list: &dev->rx.list); |
322 | |
323 | INIT_DELAYED_WORK(&dev->rx.dwork, pending_rx_work); |
324 | |
325 | dev->client = client; |
326 | i2c_set_clientdata(client, data: dev); |
327 | |
328 | ret = most_register_interface(iface: &dev->most_iface); |
329 | if (ret) { |
330 | pr_err("Failed to register i2c as a MOST interface\n" ); |
331 | kfree(objp: 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 | */ |
346 | static void i2c_remove(struct i2c_client *client) |
347 | { |
348 | struct hdm_i2c *dev = i2c_get_clientdata(client); |
349 | |
350 | most_deregister_interface(iface: &dev->most_iface); |
351 | kfree(objp: 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 | |