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 */
47struct 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
62static 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
70static 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
80static 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
91static irqreturn_t bt1_apb_isr(int irq, void *data)
92{
93 struct bt1_apb *apb = data;
94 u32 addr = 0;
95
96 regmap_read(map: apb->regs, APB_EHB_ADDR, val: &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(map: apb->regs, APB_EHB_ISR, APB_EHB_ISR_PENDING, val: 0);
113
114 return IRQ_HANDLED;
115}
116
117static 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
125static 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, size: sizeof(*apb), GFP_KERNEL);
132 if (!apb)
133 return ERR_PTR(error: -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(error: ret);
139 }
140
141 apb->dev = dev;
142 atomic_set(v: &apb->count, i: 0);
143 platform_set_drvdata(pdev, data: apb);
144
145 return apb;
146}
147
148static 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, name: "ehb");
154 if (IS_ERR(ptr: regs)) {
155 dev_err(apb->dev, "Couldn't map APB EHB registers\n");
156 return PTR_ERR(ptr: regs);
157 }
158
159 apb->regs = devm_regmap_init_mmio(apb->dev, regs, &bt1_apb_regmap_cfg);
160 if (IS_ERR(ptr: apb->regs)) {
161 dev_err(apb->dev, "Couldn't create APB EHB regmap\n");
162 return PTR_ERR(ptr: apb->regs);
163 }
164
165 apb->res = devm_platform_ioremap_resource_byname(pdev, name: "nodev");
166 if (IS_ERR(ptr: apb->res))
167 dev_err(apb->dev, "Couldn't map reserved region\n");
168
169 return PTR_ERR_OR_ZERO(ptr: apb->res);
170}
171
172static int bt1_apb_request_rst(struct bt1_apb *apb)
173{
174 int ret;
175
176 apb->prst = devm_reset_control_get_optional_exclusive(dev: apb->dev, id: "prst");
177 if (IS_ERR(ptr: apb->prst))
178 return dev_err_probe(dev: apb->dev, err: PTR_ERR(ptr: apb->prst),
179 fmt: "Couldn't get reset control line\n");
180
181 ret = reset_control_deassert(rstc: apb->prst);
182 if (ret)
183 dev_err(apb->dev, "Failed to deassert the reset line\n");
184
185 return ret;
186}
187
188static void bt1_apb_disable_clk(void *data)
189{
190 struct bt1_apb *apb = data;
191
192 clk_disable_unprepare(clk: apb->pclk);
193}
194
195static int bt1_apb_request_clk(struct bt1_apb *apb)
196{
197 int ret;
198
199 apb->pclk = devm_clk_get(dev: apb->dev, id: "pclk");
200 if (IS_ERR(ptr: apb->pclk))
201 return dev_err_probe(dev: apb->dev, err: PTR_ERR(ptr: apb->pclk),
202 fmt: "Couldn't get APB clock descriptor\n");
203
204 ret = clk_prepare_enable(clk: apb->pclk);
205 if (ret) {
206 dev_err(apb->dev, "Couldn't enable the APB clock\n");
207 return ret;
208 }
209
210 ret = devm_add_action_or_reset(apb->dev, bt1_apb_disable_clk, apb);
211 if (ret) {
212 dev_err(apb->dev, "Can't add APB EHB clocks disable action\n");
213 return ret;
214 }
215
216 apb->rate = clk_get_rate(clk: apb->pclk);
217 if (!apb->rate) {
218 dev_err(apb->dev, "Invalid clock rate\n");
219 return -EINVAL;
220 }
221
222 return 0;
223}
224
225static void bt1_apb_clear_irq(void *data)
226{
227 struct bt1_apb *apb = data;
228
229 regmap_update_bits(map: apb->regs, APB_EHB_ISR, APB_EHB_ISR_MASK, val: 0);
230}
231
232static int bt1_apb_request_irq(struct bt1_apb *apb)
233{
234 struct platform_device *pdev = to_platform_device(apb->dev);
235 int ret;
236
237 apb->irq = platform_get_irq(pdev, 0);
238 if (apb->irq < 0)
239 return apb->irq;
240
241 ret = devm_request_irq(dev: apb->dev, irq: apb->irq, handler: bt1_apb_isr, IRQF_SHARED,
242 devname: "bt1-apb", dev_id: apb);
243 if (ret) {
244 dev_err(apb->dev, "Couldn't request APB EHB IRQ\n");
245 return ret;
246 }
247
248 ret = devm_add_action(apb->dev, bt1_apb_clear_irq, apb);
249 if (ret) {
250 dev_err(apb->dev, "Can't add APB EHB IRQs clear action\n");
251 return ret;
252 }
253
254 /* Unmask IRQ and clear it' pending flag. */
255 regmap_update_bits(map: apb->regs, APB_EHB_ISR,
256 APB_EHB_ISR_PENDING | APB_EHB_ISR_MASK,
257 APB_EHB_ISR_MASK);
258
259 return 0;
260}
261
262static ssize_t count_show(struct device *dev, struct device_attribute *attr,
263 char *buf)
264{
265 struct bt1_apb *apb = dev_get_drvdata(dev);
266
267 return scnprintf(buf, PAGE_SIZE, fmt: "%d\n", atomic_read(v: &apb->count));
268}
269static DEVICE_ATTR_RO(count);
270
271static ssize_t timeout_show(struct device *dev, struct device_attribute *attr,
272 char *buf)
273{
274 struct bt1_apb *apb = dev_get_drvdata(dev);
275 unsigned long timeout;
276 int ret;
277 u32 n;
278
279 ret = regmap_read(map: apb->regs, APB_EHB_TIMEOUT, val: &n);
280 if (ret)
281 return ret;
282
283 timeout = bt1_apb_n_to_timeout_us(apb, n);
284
285 return scnprintf(buf, PAGE_SIZE, fmt: "%lu\n", timeout);
286}
287
288static ssize_t timeout_store(struct device *dev,
289 struct device_attribute *attr,
290 const char *buf, size_t count)
291{
292 struct bt1_apb *apb = dev_get_drvdata(dev);
293 unsigned long timeout;
294 int ret;
295 u32 n;
296
297 if (kstrtoul(s: buf, base: 0, res: &timeout) < 0)
298 return -EINVAL;
299
300 n = bt1_apb_timeout_to_n_us(apb, timeout);
301 n = clamp(n, APB_EHB_TIMEOUT_MIN, APB_EHB_TIMEOUT_MAX);
302
303 ret = regmap_write(map: apb->regs, APB_EHB_TIMEOUT, val: n);
304
305 return ret ?: count;
306}
307static DEVICE_ATTR_RW(timeout);
308
309static ssize_t inject_error_show(struct device *dev,
310 struct device_attribute *attr, char *buf)
311{
312 return scnprintf(buf, PAGE_SIZE, fmt: "Error injection: nodev irq\n");
313}
314
315static ssize_t inject_error_store(struct device *dev,
316 struct device_attribute *attr,
317 const char *data, size_t count)
318{
319 struct bt1_apb *apb = dev_get_drvdata(dev);
320
321 /*
322 * Either dummy read from the unmapped address in the APB IO area
323 * or manually set the IRQ status.
324 */
325 if (sysfs_streq(s1: data, s2: "nodev"))
326 readl(addr: apb->res);
327 else if (sysfs_streq(s1: data, s2: "irq"))
328 regmap_update_bits(map: apb->regs, APB_EHB_ISR, APB_EHB_ISR_PENDING,
329 APB_EHB_ISR_PENDING);
330 else
331 return -EINVAL;
332
333 return count;
334}
335static DEVICE_ATTR_RW(inject_error);
336
337static struct attribute *bt1_apb_sysfs_attrs[] = {
338 &dev_attr_count.attr,
339 &dev_attr_timeout.attr,
340 &dev_attr_inject_error.attr,
341 NULL
342};
343ATTRIBUTE_GROUPS(bt1_apb_sysfs);
344
345static void bt1_apb_remove_sysfs(void *data)
346{
347 struct bt1_apb *apb = data;
348
349 device_remove_groups(dev: apb->dev, groups: bt1_apb_sysfs_groups);
350}
351
352static int bt1_apb_init_sysfs(struct bt1_apb *apb)
353{
354 int ret;
355
356 ret = device_add_groups(dev: apb->dev, groups: bt1_apb_sysfs_groups);
357 if (ret) {
358 dev_err(apb->dev, "Failed to create EHB APB sysfs nodes\n");
359 return ret;
360 }
361
362 ret = devm_add_action_or_reset(apb->dev, bt1_apb_remove_sysfs, apb);
363 if (ret)
364 dev_err(apb->dev, "Can't add APB EHB sysfs remove action\n");
365
366 return ret;
367}
368
369static int bt1_apb_probe(struct platform_device *pdev)
370{
371 struct bt1_apb *apb;
372 int ret;
373
374 apb = bt1_apb_create_data(pdev);
375 if (IS_ERR(ptr: apb))
376 return PTR_ERR(ptr: apb);
377
378 ret = bt1_apb_request_regs(apb);
379 if (ret)
380 return ret;
381
382 ret = bt1_apb_request_rst(apb);
383 if (ret)
384 return ret;
385
386 ret = bt1_apb_request_clk(apb);
387 if (ret)
388 return ret;
389
390 ret = bt1_apb_request_irq(apb);
391 if (ret)
392 return ret;
393
394 ret = bt1_apb_init_sysfs(apb);
395 if (ret)
396 return ret;
397
398 return 0;
399}
400
401static const struct of_device_id bt1_apb_of_match[] = {
402 { .compatible = "baikal,bt1-apb" },
403 { }
404};
405MODULE_DEVICE_TABLE(of, bt1_apb_of_match);
406
407static struct platform_driver bt1_apb_driver = {
408 .probe = bt1_apb_probe,
409 .driver = {
410 .name = "bt1-apb",
411 .of_match_table = bt1_apb_of_match
412 }
413};
414module_platform_driver(bt1_apb_driver);
415
416MODULE_AUTHOR("Serge Semin <Sergey.Semin@baikalelectronics.ru>");
417MODULE_DESCRIPTION("Baikal-T1 APB-bus driver");
418

source code of linux/drivers/bus/bt1-apb.c