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