1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * Copyright (C) 2020 BAIKAL ELECTRONICS, JSC
4 *
5 * Authors:
6 * Serge Semin <Sergey.Semin@baikalelectronics.ru>
7 *
8 * Baikal-T1 APB-bus driver
9 */
10
11 #include <linux/kernel.h>
12 #include <linux/module.h>
13 #include <linux/types.h>
14 #include <linux/device.h>
15 #include <linux/atomic.h>
16 #include <linux/platform_device.h>
17 #include <linux/interrupt.h>
18 #include <linux/io.h>
19 #include <linux/nmi.h>
20 #include <linux/of.h>
21 #include <linux/regmap.h>
22 #include <linux/clk.h>
23 #include <linux/reset.h>
24 #include <linux/time64.h>
25 #include <linux/clk.h>
26 #include <linux/sysfs.h>
27
28 #define APB_EHB_ISR 0x00
29 #define APB_EHB_ISR_PENDING BIT(0)
30 #define APB_EHB_ISR_MASK BIT(1)
31 #define APB_EHB_ADDR 0x04
32 #define APB_EHB_TIMEOUT 0x08
33
34 #define APB_EHB_TIMEOUT_MIN 0x000003FFU
35 #define APB_EHB_TIMEOUT_MAX 0xFFFFFFFFU
36
37 /*
38 * struct bt1_apb - Baikal-T1 APB EHB private data
39 * @dev: Pointer to the device structure.
40 * @regs: APB EHB registers map.
41 * @res: No-device error injection memory region.
42 * @irq: Errors IRQ number.
43 * @rate: APB-bus reference clock rate.
44 * @pclk: APB-reference clock.
45 * @prst: APB domain reset line.
46 * @count: Number of errors detected.
47 */
48 struct bt1_apb {
49 struct device *dev;
50
51 struct regmap *regs;
52 void __iomem *res;
53 int irq;
54
55 unsigned long rate;
56 struct clk *pclk;
57
58 struct reset_control *prst;
59
60 atomic_t count;
61 };
62
63 static const struct regmap_config bt1_apb_regmap_cfg = {
64 .reg_bits = 32,
65 .val_bits = 32,
66 .reg_stride = 4,
67 .max_register = APB_EHB_TIMEOUT,
68 .fast_io = true
69 };
70
bt1_apb_n_to_timeout_us(struct bt1_apb * apb,u32 n)71 static inline unsigned long bt1_apb_n_to_timeout_us(struct bt1_apb *apb, u32 n)
72 {
73 u64 timeout = (u64)n * USEC_PER_SEC;
74
75 do_div(timeout, apb->rate);
76
77 return timeout;
78
79 }
80
bt1_apb_timeout_to_n_us(struct bt1_apb * apb,unsigned long timeout)81 static inline unsigned long bt1_apb_timeout_to_n_us(struct bt1_apb *apb,
82 unsigned long timeout)
83 {
84 u64 n = (u64)timeout * apb->rate;
85
86 do_div(n, USEC_PER_SEC);
87
88 return n;
89
90 }
91
bt1_apb_isr(int irq,void * data)92 static irqreturn_t bt1_apb_isr(int irq, void *data)
93 {
94 struct bt1_apb *apb = data;
95 u32 addr = 0;
96
97 regmap_read(apb->regs, APB_EHB_ADDR, &addr);
98
99 dev_crit_ratelimited(apb->dev,
100 "APB-bus fault %d: Slave access timeout at 0x%08x\n",
101 atomic_inc_return(&apb->count),
102 addr);
103
104 /*
105 * Print backtrace on each CPU. This might be pointless if the fault
106 * has happened on the same CPU as the IRQ handler is executed or
107 * the other core proceeded further execution despite the error.
108 * But if it's not, by looking at the trace we would get straight to
109 * the cause of the problem.
110 */
111 trigger_all_cpu_backtrace();
112
113 regmap_update_bits(apb->regs, APB_EHB_ISR, APB_EHB_ISR_PENDING, 0);
114
115 return IRQ_HANDLED;
116 }
117
bt1_apb_clear_data(void * data)118 static void bt1_apb_clear_data(void *data)
119 {
120 struct bt1_apb *apb = data;
121 struct platform_device *pdev = to_platform_device(apb->dev);
122
123 platform_set_drvdata(pdev, NULL);
124 }
125
bt1_apb_create_data(struct platform_device * pdev)126 static struct bt1_apb *bt1_apb_create_data(struct platform_device *pdev)
127 {
128 struct device *dev = &pdev->dev;
129 struct bt1_apb *apb;
130 int ret;
131
132 apb = devm_kzalloc(dev, sizeof(*apb), GFP_KERNEL);
133 if (!apb)
134 return ERR_PTR(-ENOMEM);
135
136 ret = devm_add_action(dev, bt1_apb_clear_data, apb);
137 if (ret) {
138 dev_err(dev, "Can't add APB EHB data clear action\n");
139 return ERR_PTR(ret);
140 }
141
142 apb->dev = dev;
143 atomic_set(&apb->count, 0);
144 platform_set_drvdata(pdev, apb);
145
146 return apb;
147 }
148
bt1_apb_request_regs(struct bt1_apb * apb)149 static int bt1_apb_request_regs(struct bt1_apb *apb)
150 {
151 struct platform_device *pdev = to_platform_device(apb->dev);
152 void __iomem *regs;
153
154 regs = devm_platform_ioremap_resource_byname(pdev, "ehb");
155 if (IS_ERR(regs)) {
156 dev_err(apb->dev, "Couldn't map APB EHB registers\n");
157 return PTR_ERR(regs);
158 }
159
160 apb->regs = devm_regmap_init_mmio(apb->dev, regs, &bt1_apb_regmap_cfg);
161 if (IS_ERR(apb->regs)) {
162 dev_err(apb->dev, "Couldn't create APB EHB regmap\n");
163 return PTR_ERR(apb->regs);
164 }
165
166 apb->res = devm_platform_ioremap_resource_byname(pdev, "nodev");
167 if (IS_ERR(apb->res))
168 dev_err(apb->dev, "Couldn't map reserved region\n");
169
170 return PTR_ERR_OR_ZERO(apb->res);
171 }
172
bt1_apb_request_rst(struct bt1_apb * apb)173 static int bt1_apb_request_rst(struct bt1_apb *apb)
174 {
175 int ret;
176
177 apb->prst = devm_reset_control_get_optional_exclusive(apb->dev, "prst");
178 if (IS_ERR(apb->prst))
179 return dev_err_probe(apb->dev, PTR_ERR(apb->prst),
180 "Couldn't get reset control line\n");
181
182 ret = reset_control_deassert(apb->prst);
183 if (ret)
184 dev_err(apb->dev, "Failed to deassert the reset line\n");
185
186 return ret;
187 }
188
bt1_apb_disable_clk(void * data)189 static void bt1_apb_disable_clk(void *data)
190 {
191 struct bt1_apb *apb = data;
192
193 clk_disable_unprepare(apb->pclk);
194 }
195
bt1_apb_request_clk(struct bt1_apb * apb)196 static int bt1_apb_request_clk(struct bt1_apb *apb)
197 {
198 int ret;
199
200 apb->pclk = devm_clk_get(apb->dev, "pclk");
201 if (IS_ERR(apb->pclk))
202 return dev_err_probe(apb->dev, PTR_ERR(apb->pclk),
203 "Couldn't get APB clock descriptor\n");
204
205 ret = clk_prepare_enable(apb->pclk);
206 if (ret) {
207 dev_err(apb->dev, "Couldn't enable the APB clock\n");
208 return ret;
209 }
210
211 ret = devm_add_action_or_reset(apb->dev, bt1_apb_disable_clk, apb);
212 if (ret) {
213 dev_err(apb->dev, "Can't add APB EHB clocks disable action\n");
214 return ret;
215 }
216
217 apb->rate = clk_get_rate(apb->pclk);
218 if (!apb->rate) {
219 dev_err(apb->dev, "Invalid clock rate\n");
220 return -EINVAL;
221 }
222
223 return 0;
224 }
225
bt1_apb_clear_irq(void * data)226 static void bt1_apb_clear_irq(void *data)
227 {
228 struct bt1_apb *apb = data;
229
230 regmap_update_bits(apb->regs, APB_EHB_ISR, APB_EHB_ISR_MASK, 0);
231 }
232
bt1_apb_request_irq(struct bt1_apb * apb)233 static int bt1_apb_request_irq(struct bt1_apb *apb)
234 {
235 struct platform_device *pdev = to_platform_device(apb->dev);
236 int ret;
237
238 apb->irq = platform_get_irq(pdev, 0);
239 if (apb->irq < 0)
240 return apb->irq;
241
242 ret = devm_request_irq(apb->dev, apb->irq, bt1_apb_isr, IRQF_SHARED,
243 "bt1-apb", apb);
244 if (ret) {
245 dev_err(apb->dev, "Couldn't request APB EHB IRQ\n");
246 return ret;
247 }
248
249 ret = devm_add_action(apb->dev, bt1_apb_clear_irq, apb);
250 if (ret) {
251 dev_err(apb->dev, "Can't add APB EHB IRQs clear action\n");
252 return ret;
253 }
254
255 /* Unmask IRQ and clear it' pending flag. */
256 regmap_update_bits(apb->regs, APB_EHB_ISR,
257 APB_EHB_ISR_PENDING | APB_EHB_ISR_MASK,
258 APB_EHB_ISR_MASK);
259
260 return 0;
261 }
262
count_show(struct device * dev,struct device_attribute * attr,char * buf)263 static ssize_t count_show(struct device *dev, struct device_attribute *attr,
264 char *buf)
265 {
266 struct bt1_apb *apb = dev_get_drvdata(dev);
267
268 return scnprintf(buf, PAGE_SIZE, "%d\n", atomic_read(&apb->count));
269 }
270 static DEVICE_ATTR_RO(count);
271
timeout_show(struct device * dev,struct device_attribute * attr,char * buf)272 static ssize_t timeout_show(struct device *dev, struct device_attribute *attr,
273 char *buf)
274 {
275 struct bt1_apb *apb = dev_get_drvdata(dev);
276 unsigned long timeout;
277 int ret;
278 u32 n;
279
280 ret = regmap_read(apb->regs, APB_EHB_TIMEOUT, &n);
281 if (ret)
282 return ret;
283
284 timeout = bt1_apb_n_to_timeout_us(apb, n);
285
286 return scnprintf(buf, PAGE_SIZE, "%lu\n", timeout);
287 }
288
timeout_store(struct device * dev,struct device_attribute * attr,const char * buf,size_t count)289 static ssize_t timeout_store(struct device *dev,
290 struct device_attribute *attr,
291 const char *buf, size_t count)
292 {
293 struct bt1_apb *apb = dev_get_drvdata(dev);
294 unsigned long timeout;
295 int ret;
296 u32 n;
297
298 if (kstrtoul(buf, 0, &timeout) < 0)
299 return -EINVAL;
300
301 n = bt1_apb_timeout_to_n_us(apb, timeout);
302 n = clamp(n, APB_EHB_TIMEOUT_MIN, APB_EHB_TIMEOUT_MAX);
303
304 ret = regmap_write(apb->regs, APB_EHB_TIMEOUT, n);
305
306 return ret ?: count;
307 }
308 static DEVICE_ATTR_RW(timeout);
309
inject_error_show(struct device * dev,struct device_attribute * attr,char * buf)310 static ssize_t inject_error_show(struct device *dev,
311 struct device_attribute *attr, char *buf)
312 {
313 return scnprintf(buf, PAGE_SIZE, "Error injection: nodev irq\n");
314 }
315
inject_error_store(struct device * dev,struct device_attribute * attr,const char * data,size_t count)316 static ssize_t inject_error_store(struct device *dev,
317 struct device_attribute *attr,
318 const char *data, size_t count)
319 {
320 struct bt1_apb *apb = dev_get_drvdata(dev);
321
322 /*
323 * Either dummy read from the unmapped address in the APB IO area
324 * or manually set the IRQ status.
325 */
326 if (sysfs_streq(data, "nodev"))
327 readl(apb->res);
328 else if (sysfs_streq(data, "irq"))
329 regmap_update_bits(apb->regs, APB_EHB_ISR, APB_EHB_ISR_PENDING,
330 APB_EHB_ISR_PENDING);
331 else
332 return -EINVAL;
333
334 return count;
335 }
336 static DEVICE_ATTR_RW(inject_error);
337
338 static struct attribute *bt1_apb_sysfs_attrs[] = {
339 &dev_attr_count.attr,
340 &dev_attr_timeout.attr,
341 &dev_attr_inject_error.attr,
342 NULL
343 };
344 ATTRIBUTE_GROUPS(bt1_apb_sysfs);
345
bt1_apb_remove_sysfs(void * data)346 static void bt1_apb_remove_sysfs(void *data)
347 {
348 struct bt1_apb *apb = data;
349
350 device_remove_groups(apb->dev, bt1_apb_sysfs_groups);
351 }
352
bt1_apb_init_sysfs(struct bt1_apb * apb)353 static int bt1_apb_init_sysfs(struct bt1_apb *apb)
354 {
355 int ret;
356
357 ret = device_add_groups(apb->dev, bt1_apb_sysfs_groups);
358 if (ret) {
359 dev_err(apb->dev, "Failed to create EHB APB sysfs nodes\n");
360 return ret;
361 }
362
363 ret = devm_add_action_or_reset(apb->dev, bt1_apb_remove_sysfs, apb);
364 if (ret)
365 dev_err(apb->dev, "Can't add APB EHB sysfs remove action\n");
366
367 return ret;
368 }
369
bt1_apb_probe(struct platform_device * pdev)370 static int bt1_apb_probe(struct platform_device *pdev)
371 {
372 struct bt1_apb *apb;
373 int ret;
374
375 apb = bt1_apb_create_data(pdev);
376 if (IS_ERR(apb))
377 return PTR_ERR(apb);
378
379 ret = bt1_apb_request_regs(apb);
380 if (ret)
381 return ret;
382
383 ret = bt1_apb_request_rst(apb);
384 if (ret)
385 return ret;
386
387 ret = bt1_apb_request_clk(apb);
388 if (ret)
389 return ret;
390
391 ret = bt1_apb_request_irq(apb);
392 if (ret)
393 return ret;
394
395 ret = bt1_apb_init_sysfs(apb);
396 if (ret)
397 return ret;
398
399 return 0;
400 }
401
402 static const struct of_device_id bt1_apb_of_match[] = {
403 { .compatible = "baikal,bt1-apb" },
404 { }
405 };
406 MODULE_DEVICE_TABLE(of, bt1_apb_of_match);
407
408 static struct platform_driver bt1_apb_driver = {
409 .probe = bt1_apb_probe,
410 .driver = {
411 .name = "bt1-apb",
412 .of_match_table = bt1_apb_of_match
413 }
414 };
415 module_platform_driver(bt1_apb_driver);
416
417 MODULE_AUTHOR("Serge Semin <Sergey.Semin@baikalelectronics.ru>");
418 MODULE_DESCRIPTION("Baikal-T1 APB-bus driver");
419