1 // SPDX-License-Identifier: GPL-2.0-only
3 * Copyright (C) 2020 BAIKAL ELECTRONICS, JSC
6 * Serge Semin <Sergey.Semin@baikalelectronics.ru>
8 * Baikal-T1 APB-bus driver
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>
19 #include <linux/nmi.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>
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
33 #define APB_EHB_TIMEOUT_MIN 0x000003FFU
34 #define APB_EHB_TIMEOUT_MAX 0xFFFFFFFFU
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.
57 struct reset_control *prst;
62 static const struct regmap_config bt1_apb_regmap_cfg = {
66 .max_register = APB_EHB_TIMEOUT,
70 static inline unsigned long bt1_apb_n_to_timeout_us(struct bt1_apb *apb, u32 n)
72 u64 timeout = (u64)n * USEC_PER_SEC;
74 do_div(timeout, apb->rate);
80 static inline unsigned long bt1_apb_timeout_to_n_us(struct bt1_apb *apb,
81 unsigned long timeout)
83 u64 n = (u64)timeout * apb->rate;
85 do_div(n, USEC_PER_SEC);
91 static irqreturn_t bt1_apb_isr(int irq, void *data)
93 struct bt1_apb *apb = data;
96 regmap_read(apb->regs, APB_EHB_ADDR, &addr);
98 dev_crit_ratelimited(apb->dev,
99 "APB-bus fault %d: Slave access timeout at 0x%08x\n",
100 atomic_inc_return(&apb->count),
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.
110 trigger_all_cpu_backtrace();
112 regmap_update_bits(apb->regs, APB_EHB_ISR, APB_EHB_ISR_PENDING, 0);
117 static void bt1_apb_clear_data(void *data)
119 struct bt1_apb *apb = data;
120 struct platform_device *pdev = to_platform_device(apb->dev);
122 platform_set_drvdata(pdev, NULL);
125 static struct bt1_apb *bt1_apb_create_data(struct platform_device *pdev)
127 struct device *dev = &pdev->dev;
131 apb = devm_kzalloc(dev, sizeof(*apb), GFP_KERNEL);
133 return ERR_PTR(-ENOMEM);
135 ret = devm_add_action(dev, bt1_apb_clear_data, apb);
137 dev_err(dev, "Can't add APB EHB data clear action\n");
142 atomic_set(&apb->count, 0);
143 platform_set_drvdata(pdev, apb);
148 static int bt1_apb_request_regs(struct bt1_apb *apb)
150 struct platform_device *pdev = to_platform_device(apb->dev);
153 regs = devm_platform_ioremap_resource_byname(pdev, "ehb");
155 dev_err(apb->dev, "Couldn't map APB EHB registers\n");
156 return PTR_ERR(regs);
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);
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");
169 return PTR_ERR_OR_ZERO(apb->res);
172 static int bt1_apb_request_rst(struct bt1_apb *apb)
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");
181 ret = reset_control_deassert(apb->prst);
183 dev_err(apb->dev, "Failed to deassert the reset line\n");
188 static void bt1_apb_disable_clk(void *data)
190 struct bt1_apb *apb = data;
192 clk_disable_unprepare(apb->pclk);
195 static int bt1_apb_request_clk(struct bt1_apb *apb)
199 apb->pclk = devm_clk_get(apb->dev, "pclk");
200 if (IS_ERR(apb->pclk))
201 return dev_err_probe(apb->dev, PTR_ERR(apb->pclk),
202 "Couldn't get APB clock descriptor\n");
204 ret = clk_prepare_enable(apb->pclk);
206 dev_err(apb->dev, "Couldn't enable the APB clock\n");
210 ret = devm_add_action_or_reset(apb->dev, bt1_apb_disable_clk, apb);
212 dev_err(apb->dev, "Can't add APB EHB clocks disable action\n");
216 apb->rate = clk_get_rate(apb->pclk);
218 dev_err(apb->dev, "Invalid clock rate\n");
225 static void bt1_apb_clear_irq(void *data)
227 struct bt1_apb *apb = data;
229 regmap_update_bits(apb->regs, APB_EHB_ISR, APB_EHB_ISR_MASK, 0);
232 static int bt1_apb_request_irq(struct bt1_apb *apb)
234 struct platform_device *pdev = to_platform_device(apb->dev);
237 apb->irq = platform_get_irq(pdev, 0);
241 ret = devm_request_irq(apb->dev, apb->irq, bt1_apb_isr, IRQF_SHARED,
244 dev_err(apb->dev, "Couldn't request APB EHB IRQ\n");
248 ret = devm_add_action(apb->dev, bt1_apb_clear_irq, apb);
250 dev_err(apb->dev, "Can't add APB EHB IRQs clear action\n");
254 /* Unmask IRQ and clear it' pending flag. */
255 regmap_update_bits(apb->regs, APB_EHB_ISR,
256 APB_EHB_ISR_PENDING | APB_EHB_ISR_MASK,
262 static ssize_t count_show(struct device *dev, struct device_attribute *attr,
265 struct bt1_apb *apb = dev_get_drvdata(dev);
267 return scnprintf(buf, PAGE_SIZE, "%d\n", atomic_read(&apb->count));
269 static DEVICE_ATTR_RO(count);
271 static ssize_t timeout_show(struct device *dev, struct device_attribute *attr,
274 struct bt1_apb *apb = dev_get_drvdata(dev);
275 unsigned long timeout;
279 ret = regmap_read(apb->regs, APB_EHB_TIMEOUT, &n);
283 timeout = bt1_apb_n_to_timeout_us(apb, n);
285 return scnprintf(buf, PAGE_SIZE, "%lu\n", timeout);
288 static ssize_t timeout_store(struct device *dev,
289 struct device_attribute *attr,
290 const char *buf, size_t count)
292 struct bt1_apb *apb = dev_get_drvdata(dev);
293 unsigned long timeout;
297 if (kstrtoul(buf, 0, &timeout) < 0)
300 n = bt1_apb_timeout_to_n_us(apb, timeout);
301 n = clamp(n, APB_EHB_TIMEOUT_MIN, APB_EHB_TIMEOUT_MAX);
303 ret = regmap_write(apb->regs, APB_EHB_TIMEOUT, n);
307 static DEVICE_ATTR_RW(timeout);
309 static ssize_t inject_error_show(struct device *dev,
310 struct device_attribute *attr, char *buf)
312 return scnprintf(buf, PAGE_SIZE, "Error injection: nodev irq\n");
315 static ssize_t inject_error_store(struct device *dev,
316 struct device_attribute *attr,
317 const char *data, size_t count)
319 struct bt1_apb *apb = dev_get_drvdata(dev);
322 * Either dummy read from the unmapped address in the APB IO area
323 * or manually set the IRQ status.
325 if (sysfs_streq(data, "nodev"))
327 else if (sysfs_streq(data, "irq"))
328 regmap_update_bits(apb->regs, APB_EHB_ISR, APB_EHB_ISR_PENDING,
329 APB_EHB_ISR_PENDING);
335 static DEVICE_ATTR_RW(inject_error);
337 static struct attribute *bt1_apb_sysfs_attrs[] = {
338 &dev_attr_count.attr,
339 &dev_attr_timeout.attr,
340 &dev_attr_inject_error.attr,
343 ATTRIBUTE_GROUPS(bt1_apb_sysfs);
345 static void bt1_apb_remove_sysfs(void *data)
347 struct bt1_apb *apb = data;
349 device_remove_groups(apb->dev, bt1_apb_sysfs_groups);
352 static int bt1_apb_init_sysfs(struct bt1_apb *apb)
356 ret = device_add_groups(apb->dev, bt1_apb_sysfs_groups);
358 dev_err(apb->dev, "Failed to create EHB APB sysfs nodes\n");
362 ret = devm_add_action_or_reset(apb->dev, bt1_apb_remove_sysfs, apb);
364 dev_err(apb->dev, "Can't add APB EHB sysfs remove action\n");
369 static int bt1_apb_probe(struct platform_device *pdev)
374 apb = bt1_apb_create_data(pdev);
378 ret = bt1_apb_request_regs(apb);
382 ret = bt1_apb_request_rst(apb);
386 ret = bt1_apb_request_clk(apb);
390 ret = bt1_apb_request_irq(apb);
394 ret = bt1_apb_init_sysfs(apb);
401 static const struct of_device_id bt1_apb_of_match[] = {
402 { .compatible = "baikal,bt1-apb" },
405 MODULE_DEVICE_TABLE(of, bt1_apb_of_match);
407 static struct platform_driver bt1_apb_driver = {
408 .probe = bt1_apb_probe,
411 .of_match_table = bt1_apb_of_match
414 module_platform_driver(bt1_apb_driver);
416 MODULE_AUTHOR("Serge Semin <Sergey.Semin@baikalelectronics.ru>");
417 MODULE_DESCRIPTION("Baikal-T1 APB-bus driver");