1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * Copyright 2017 Google Inc
4 *
5 * Provides a simple driver to control the ASPEED LPC snoop interface which
6 * allows the BMC to listen on and save the data written by
7 * the host to an arbitrary LPC I/O port.
8 *
9 * Typically used by the BMC to "watch" host boot progress via port
10 * 0x80 writes made by the BIOS during the boot process.
11 */
12
13 #include <linux/bitops.h>
14 #include <linux/clk.h>
15 #include <linux/interrupt.h>
16 #include <linux/fs.h>
17 #include <linux/kfifo.h>
18 #include <linux/mfd/syscon.h>
19 #include <linux/miscdevice.h>
20 #include <linux/module.h>
21 #include <linux/of.h>
22 #include <linux/platform_device.h>
23 #include <linux/poll.h>
24 #include <linux/regmap.h>
25
26 #define DEVICE_NAME "aspeed-lpc-snoop"
27
28 #define NUM_SNOOP_CHANNELS 2
29 #define SNOOP_FIFO_SIZE 2048
30
31 #define HICR5 0x80
32 #define HICR5_EN_SNP0W BIT(0)
33 #define HICR5_ENINT_SNP0W BIT(1)
34 #define HICR5_EN_SNP1W BIT(2)
35 #define HICR5_ENINT_SNP1W BIT(3)
36 #define HICR6 0x84
37 #define HICR6_STR_SNP0W BIT(0)
38 #define HICR6_STR_SNP1W BIT(1)
39 #define SNPWADR 0x90
40 #define SNPWADR_CH0_MASK GENMASK(15, 0)
41 #define SNPWADR_CH0_SHIFT 0
42 #define SNPWADR_CH1_MASK GENMASK(31, 16)
43 #define SNPWADR_CH1_SHIFT 16
44 #define SNPWDR 0x94
45 #define SNPWDR_CH0_MASK GENMASK(7, 0)
46 #define SNPWDR_CH0_SHIFT 0
47 #define SNPWDR_CH1_MASK GENMASK(15, 8)
48 #define SNPWDR_CH1_SHIFT 8
49 #define HICRB 0x100
50 #define HICRB_ENSNP0D BIT(14)
51 #define HICRB_ENSNP1D BIT(15)
52
53 struct aspeed_lpc_snoop_model_data {
54 /* The ast2400 has bits 14 and 15 as reserved, whereas the ast2500
55 * can use them.
56 */
57 unsigned int has_hicrb_ensnp;
58 };
59
60 struct aspeed_lpc_snoop_channel {
61 struct kfifo fifo;
62 wait_queue_head_t wq;
63 struct miscdevice miscdev;
64 };
65
66 struct aspeed_lpc_snoop {
67 struct regmap *regmap;
68 int irq;
69 struct clk *clk;
70 struct aspeed_lpc_snoop_channel chan[NUM_SNOOP_CHANNELS];
71 };
72
snoop_file_to_chan(struct file * file)73 static struct aspeed_lpc_snoop_channel *snoop_file_to_chan(struct file *file)
74 {
75 return container_of(file->private_data,
76 struct aspeed_lpc_snoop_channel,
77 miscdev);
78 }
79
snoop_file_read(struct file * file,char __user * buffer,size_t count,loff_t * ppos)80 static ssize_t snoop_file_read(struct file *file, char __user *buffer,
81 size_t count, loff_t *ppos)
82 {
83 struct aspeed_lpc_snoop_channel *chan = snoop_file_to_chan(file);
84 unsigned int copied;
85 int ret = 0;
86
87 if (kfifo_is_empty(&chan->fifo)) {
88 if (file->f_flags & O_NONBLOCK)
89 return -EAGAIN;
90 ret = wait_event_interruptible(chan->wq,
91 !kfifo_is_empty(&chan->fifo));
92 if (ret == -ERESTARTSYS)
93 return -EINTR;
94 }
95 ret = kfifo_to_user(&chan->fifo, buffer, count, &copied);
96 if (ret)
97 return ret;
98
99 return copied;
100 }
101
snoop_file_poll(struct file * file,struct poll_table_struct * pt)102 static __poll_t snoop_file_poll(struct file *file,
103 struct poll_table_struct *pt)
104 {
105 struct aspeed_lpc_snoop_channel *chan = snoop_file_to_chan(file);
106
107 poll_wait(file, &chan->wq, pt);
108 return !kfifo_is_empty(&chan->fifo) ? EPOLLIN : 0;
109 }
110
111 static const struct file_operations snoop_fops = {
112 .owner = THIS_MODULE,
113 .read = snoop_file_read,
114 .poll = snoop_file_poll,
115 .llseek = noop_llseek,
116 };
117
118 /* Save a byte to a FIFO and discard the oldest byte if FIFO is full */
put_fifo_with_discard(struct aspeed_lpc_snoop_channel * chan,u8 val)119 static void put_fifo_with_discard(struct aspeed_lpc_snoop_channel *chan, u8 val)
120 {
121 if (!kfifo_initialized(&chan->fifo))
122 return;
123 if (kfifo_is_full(&chan->fifo))
124 kfifo_skip(&chan->fifo);
125 kfifo_put(&chan->fifo, val);
126 wake_up_interruptible(&chan->wq);
127 }
128
aspeed_lpc_snoop_irq(int irq,void * arg)129 static irqreturn_t aspeed_lpc_snoop_irq(int irq, void *arg)
130 {
131 struct aspeed_lpc_snoop *lpc_snoop = arg;
132 u32 reg, data;
133
134 if (regmap_read(lpc_snoop->regmap, HICR6, ®))
135 return IRQ_NONE;
136
137 /* Check if one of the snoop channels is interrupting */
138 reg &= (HICR6_STR_SNP0W | HICR6_STR_SNP1W);
139 if (!reg)
140 return IRQ_NONE;
141
142 /* Ack pending IRQs */
143 regmap_write(lpc_snoop->regmap, HICR6, reg);
144
145 /* Read and save most recent snoop'ed data byte to FIFO */
146 regmap_read(lpc_snoop->regmap, SNPWDR, &data);
147
148 if (reg & HICR6_STR_SNP0W) {
149 u8 val = (data & SNPWDR_CH0_MASK) >> SNPWDR_CH0_SHIFT;
150
151 put_fifo_with_discard(&lpc_snoop->chan[0], val);
152 }
153 if (reg & HICR6_STR_SNP1W) {
154 u8 val = (data & SNPWDR_CH1_MASK) >> SNPWDR_CH1_SHIFT;
155
156 put_fifo_with_discard(&lpc_snoop->chan[1], val);
157 }
158
159 return IRQ_HANDLED;
160 }
161
aspeed_lpc_snoop_config_irq(struct aspeed_lpc_snoop * lpc_snoop,struct platform_device * pdev)162 static int aspeed_lpc_snoop_config_irq(struct aspeed_lpc_snoop *lpc_snoop,
163 struct platform_device *pdev)
164 {
165 struct device *dev = &pdev->dev;
166 int rc;
167
168 lpc_snoop->irq = platform_get_irq(pdev, 0);
169 if (!lpc_snoop->irq)
170 return -ENODEV;
171
172 rc = devm_request_irq(dev, lpc_snoop->irq,
173 aspeed_lpc_snoop_irq, IRQF_SHARED,
174 DEVICE_NAME, lpc_snoop);
175 if (rc < 0) {
176 dev_warn(dev, "Unable to request IRQ %d\n", lpc_snoop->irq);
177 lpc_snoop->irq = 0;
178 return rc;
179 }
180
181 return 0;
182 }
183
aspeed_lpc_enable_snoop(struct aspeed_lpc_snoop * lpc_snoop,struct device * dev,int channel,u16 lpc_port)184 static int aspeed_lpc_enable_snoop(struct aspeed_lpc_snoop *lpc_snoop,
185 struct device *dev,
186 int channel, u16 lpc_port)
187 {
188 int rc = 0;
189 u32 hicr5_en, snpwadr_mask, snpwadr_shift, hicrb_en;
190 const struct aspeed_lpc_snoop_model_data *model_data =
191 of_device_get_match_data(dev);
192
193 init_waitqueue_head(&lpc_snoop->chan[channel].wq);
194 /* Create FIFO datastructure */
195 rc = kfifo_alloc(&lpc_snoop->chan[channel].fifo,
196 SNOOP_FIFO_SIZE, GFP_KERNEL);
197 if (rc)
198 return rc;
199
200 lpc_snoop->chan[channel].miscdev.minor = MISC_DYNAMIC_MINOR;
201 lpc_snoop->chan[channel].miscdev.name =
202 devm_kasprintf(dev, GFP_KERNEL, "%s%d", DEVICE_NAME, channel);
203 lpc_snoop->chan[channel].miscdev.fops = &snoop_fops;
204 lpc_snoop->chan[channel].miscdev.parent = dev;
205 rc = misc_register(&lpc_snoop->chan[channel].miscdev);
206 if (rc)
207 return rc;
208
209 /* Enable LPC snoop channel at requested port */
210 switch (channel) {
211 case 0:
212 hicr5_en = HICR5_EN_SNP0W | HICR5_ENINT_SNP0W;
213 snpwadr_mask = SNPWADR_CH0_MASK;
214 snpwadr_shift = SNPWADR_CH0_SHIFT;
215 hicrb_en = HICRB_ENSNP0D;
216 break;
217 case 1:
218 hicr5_en = HICR5_EN_SNP1W | HICR5_ENINT_SNP1W;
219 snpwadr_mask = SNPWADR_CH1_MASK;
220 snpwadr_shift = SNPWADR_CH1_SHIFT;
221 hicrb_en = HICRB_ENSNP1D;
222 break;
223 default:
224 return -EINVAL;
225 }
226
227 regmap_update_bits(lpc_snoop->regmap, HICR5, hicr5_en, hicr5_en);
228 regmap_update_bits(lpc_snoop->regmap, SNPWADR, snpwadr_mask,
229 lpc_port << snpwadr_shift);
230 if (model_data->has_hicrb_ensnp)
231 regmap_update_bits(lpc_snoop->regmap, HICRB,
232 hicrb_en, hicrb_en);
233
234 return rc;
235 }
236
aspeed_lpc_disable_snoop(struct aspeed_lpc_snoop * lpc_snoop,int channel)237 static void aspeed_lpc_disable_snoop(struct aspeed_lpc_snoop *lpc_snoop,
238 int channel)
239 {
240 switch (channel) {
241 case 0:
242 regmap_update_bits(lpc_snoop->regmap, HICR5,
243 HICR5_EN_SNP0W | HICR5_ENINT_SNP0W,
244 0);
245 break;
246 case 1:
247 regmap_update_bits(lpc_snoop->regmap, HICR5,
248 HICR5_EN_SNP1W | HICR5_ENINT_SNP1W,
249 0);
250 break;
251 default:
252 return;
253 }
254
255 kfifo_free(&lpc_snoop->chan[channel].fifo);
256 misc_deregister(&lpc_snoop->chan[channel].miscdev);
257 }
258
aspeed_lpc_snoop_probe(struct platform_device * pdev)259 static int aspeed_lpc_snoop_probe(struct platform_device *pdev)
260 {
261 struct aspeed_lpc_snoop *lpc_snoop;
262 struct device *dev;
263 struct device_node *np;
264 u32 port;
265 int rc;
266
267 dev = &pdev->dev;
268
269 lpc_snoop = devm_kzalloc(dev, sizeof(*lpc_snoop), GFP_KERNEL);
270 if (!lpc_snoop)
271 return -ENOMEM;
272
273 np = pdev->dev.parent->of_node;
274 if (!of_device_is_compatible(np, "aspeed,ast2400-lpc-v2") &&
275 !of_device_is_compatible(np, "aspeed,ast2500-lpc-v2") &&
276 !of_device_is_compatible(np, "aspeed,ast2600-lpc-v2")) {
277 dev_err(dev, "unsupported LPC device binding\n");
278 return -ENODEV;
279 }
280
281 lpc_snoop->regmap = syscon_node_to_regmap(np);
282 if (IS_ERR(lpc_snoop->regmap)) {
283 dev_err(dev, "Couldn't get regmap\n");
284 return -ENODEV;
285 }
286
287 dev_set_drvdata(&pdev->dev, lpc_snoop);
288
289 rc = of_property_read_u32_index(dev->of_node, "snoop-ports", 0, &port);
290 if (rc) {
291 dev_err(dev, "no snoop ports configured\n");
292 return -ENODEV;
293 }
294
295 lpc_snoop->clk = devm_clk_get(dev, NULL);
296 if (IS_ERR(lpc_snoop->clk)) {
297 rc = PTR_ERR(lpc_snoop->clk);
298 if (rc != -EPROBE_DEFER)
299 dev_err(dev, "couldn't get clock\n");
300 return rc;
301 }
302 rc = clk_prepare_enable(lpc_snoop->clk);
303 if (rc) {
304 dev_err(dev, "couldn't enable clock\n");
305 return rc;
306 }
307
308 rc = aspeed_lpc_snoop_config_irq(lpc_snoop, pdev);
309 if (rc)
310 goto err;
311
312 rc = aspeed_lpc_enable_snoop(lpc_snoop, dev, 0, port);
313 if (rc)
314 goto err;
315
316 /* Configuration of 2nd snoop channel port is optional */
317 if (of_property_read_u32_index(dev->of_node, "snoop-ports",
318 1, &port) == 0) {
319 rc = aspeed_lpc_enable_snoop(lpc_snoop, dev, 1, port);
320 if (rc) {
321 aspeed_lpc_disable_snoop(lpc_snoop, 0);
322 goto err;
323 }
324 }
325
326 return 0;
327
328 err:
329 clk_disable_unprepare(lpc_snoop->clk);
330
331 return rc;
332 }
333
aspeed_lpc_snoop_remove(struct platform_device * pdev)334 static void aspeed_lpc_snoop_remove(struct platform_device *pdev)
335 {
336 struct aspeed_lpc_snoop *lpc_snoop = dev_get_drvdata(&pdev->dev);
337
338 /* Disable both snoop channels */
339 aspeed_lpc_disable_snoop(lpc_snoop, 0);
340 aspeed_lpc_disable_snoop(lpc_snoop, 1);
341
342 clk_disable_unprepare(lpc_snoop->clk);
343 }
344
345 static const struct aspeed_lpc_snoop_model_data ast2400_model_data = {
346 .has_hicrb_ensnp = 0,
347 };
348
349 static const struct aspeed_lpc_snoop_model_data ast2500_model_data = {
350 .has_hicrb_ensnp = 1,
351 };
352
353 static const struct of_device_id aspeed_lpc_snoop_match[] = {
354 { .compatible = "aspeed,ast2400-lpc-snoop",
355 .data = &ast2400_model_data },
356 { .compatible = "aspeed,ast2500-lpc-snoop",
357 .data = &ast2500_model_data },
358 { .compatible = "aspeed,ast2600-lpc-snoop",
359 .data = &ast2500_model_data },
360 { },
361 };
362
363 static struct platform_driver aspeed_lpc_snoop_driver = {
364 .driver = {
365 .name = DEVICE_NAME,
366 .of_match_table = aspeed_lpc_snoop_match,
367 },
368 .probe = aspeed_lpc_snoop_probe,
369 .remove_new = aspeed_lpc_snoop_remove,
370 };
371
372 module_platform_driver(aspeed_lpc_snoop_driver);
373
374 MODULE_DEVICE_TABLE(of, aspeed_lpc_snoop_match);
375 MODULE_LICENSE("GPL");
376 MODULE_AUTHOR("Robert Lippert <rlippert@google.com>");
377 MODULE_DESCRIPTION("Linux driver to control Aspeed LPC snoop functionality");
378