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 AXI-bus driver
9  */
10 
11 #include <linux/kernel.h>
12 #include <linux/module.h>
13 #include <linux/types.h>
14 #include <linux/bitfield.h>
15 #include <linux/device.h>
16 #include <linux/atomic.h>
17 #include <linux/regmap.h>
18 #include <linux/platform_device.h>
19 #include <linux/mfd/syscon.h>
20 #include <linux/interrupt.h>
21 #include <linux/io.h>
22 #include <linux/nmi.h>
23 #include <linux/of.h>
24 #include <linux/clk.h>
25 #include <linux/reset.h>
26 #include <linux/sysfs.h>
27 
28 #define BT1_AXI_WERRL			0x110
29 #define BT1_AXI_WERRH			0x114
30 #define BT1_AXI_WERRH_TYPE		BIT(23)
31 #define BT1_AXI_WERRH_ADDR_FLD		24
32 #define BT1_AXI_WERRH_ADDR_MASK		GENMASK(31, BT1_AXI_WERRH_ADDR_FLD)
33 
34 /*
35  * struct bt1_axi - Baikal-T1 AXI-bus private data
36  * @dev: Pointer to the device structure.
37  * @qos_regs: AXI Interconnect QoS tuning registers.
38  * @sys_regs: Baikal-T1 System Controller registers map.
39  * @irq: Errors IRQ number.
40  * @aclk: AXI reference clock.
41  * @arst: AXI Interconnect reset line.
42  * @count: Number of errors detected.
43  */
44 struct bt1_axi {
45 	struct device *dev;
46 
47 	void __iomem *qos_regs;
48 	struct regmap *sys_regs;
49 	int irq;
50 
51 	struct clk *aclk;
52 
53 	struct reset_control *arst;
54 
55 	atomic_t count;
56 };
57 
bt1_axi_isr(int irq,void * data)58 static irqreturn_t bt1_axi_isr(int irq, void *data)
59 {
60 	struct bt1_axi *axi = data;
61 	u32 low = 0, high = 0;
62 
63 	regmap_read(axi->sys_regs, BT1_AXI_WERRL, &low);
64 	regmap_read(axi->sys_regs, BT1_AXI_WERRH, &high);
65 
66 	dev_crit_ratelimited(axi->dev,
67 		"AXI-bus fault %d: %s at 0x%x%08x\n",
68 		atomic_inc_return(&axi->count),
69 		high & BT1_AXI_WERRH_TYPE ? "no slave" : "slave protocol error",
70 		high, low);
71 
72 	/*
73 	 * Print backtrace on each CPU. This might be pointless if the fault
74 	 * has happened on the same CPU as the IRQ handler is executed or
75 	 * the other core proceeded further execution despite the error.
76 	 * But if it's not, by looking at the trace we would get straight to
77 	 * the cause of the problem.
78 	 */
79 	trigger_all_cpu_backtrace();
80 
81 	return IRQ_HANDLED;
82 }
83 
bt1_axi_clear_data(void * data)84 static void bt1_axi_clear_data(void *data)
85 {
86 	struct bt1_axi *axi = data;
87 	struct platform_device *pdev = to_platform_device(axi->dev);
88 
89 	platform_set_drvdata(pdev, NULL);
90 }
91 
bt1_axi_create_data(struct platform_device * pdev)92 static struct bt1_axi *bt1_axi_create_data(struct platform_device *pdev)
93 {
94 	struct device *dev = &pdev->dev;
95 	struct bt1_axi *axi;
96 	int ret;
97 
98 	axi = devm_kzalloc(dev, sizeof(*axi), GFP_KERNEL);
99 	if (!axi)
100 		return ERR_PTR(-ENOMEM);
101 
102 	ret = devm_add_action(dev, bt1_axi_clear_data, axi);
103 	if (ret) {
104 		dev_err(dev, "Can't add AXI EHB data clear action\n");
105 		return ERR_PTR(ret);
106 	}
107 
108 	axi->dev = dev;
109 	atomic_set(&axi->count, 0);
110 	platform_set_drvdata(pdev, axi);
111 
112 	return axi;
113 }
114 
bt1_axi_request_regs(struct bt1_axi * axi)115 static int bt1_axi_request_regs(struct bt1_axi *axi)
116 {
117 	struct platform_device *pdev = to_platform_device(axi->dev);
118 	struct device *dev = axi->dev;
119 
120 	axi->sys_regs = syscon_regmap_lookup_by_phandle(dev->of_node, "syscon");
121 	if (IS_ERR(axi->sys_regs)) {
122 		dev_err(dev, "Couldn't find syscon registers\n");
123 		return PTR_ERR(axi->sys_regs);
124 	}
125 
126 	axi->qos_regs = devm_platform_ioremap_resource_byname(pdev, "qos");
127 	if (IS_ERR(axi->qos_regs))
128 		dev_err(dev, "Couldn't map AXI-bus QoS registers\n");
129 
130 	return PTR_ERR_OR_ZERO(axi->qos_regs);
131 }
132 
bt1_axi_request_rst(struct bt1_axi * axi)133 static int bt1_axi_request_rst(struct bt1_axi *axi)
134 {
135 	int ret;
136 
137 	axi->arst = devm_reset_control_get_optional_exclusive(axi->dev, "arst");
138 	if (IS_ERR(axi->arst))
139 		return dev_err_probe(axi->dev, PTR_ERR(axi->arst),
140 				     "Couldn't get reset control line\n");
141 
142 	ret = reset_control_deassert(axi->arst);
143 	if (ret)
144 		dev_err(axi->dev, "Failed to deassert the reset line\n");
145 
146 	return ret;
147 }
148 
bt1_axi_disable_clk(void * data)149 static void bt1_axi_disable_clk(void *data)
150 {
151 	struct bt1_axi *axi = data;
152 
153 	clk_disable_unprepare(axi->aclk);
154 }
155 
bt1_axi_request_clk(struct bt1_axi * axi)156 static int bt1_axi_request_clk(struct bt1_axi *axi)
157 {
158 	int ret;
159 
160 	axi->aclk = devm_clk_get(axi->dev, "aclk");
161 	if (IS_ERR(axi->aclk))
162 		return dev_err_probe(axi->dev, PTR_ERR(axi->aclk),
163 				     "Couldn't get AXI Interconnect clock\n");
164 
165 	ret = clk_prepare_enable(axi->aclk);
166 	if (ret) {
167 		dev_err(axi->dev, "Couldn't enable the AXI clock\n");
168 		return ret;
169 	}
170 
171 	ret = devm_add_action_or_reset(axi->dev, bt1_axi_disable_clk, axi);
172 	if (ret)
173 		dev_err(axi->dev, "Can't add AXI clock disable action\n");
174 
175 	return ret;
176 }
177 
bt1_axi_request_irq(struct bt1_axi * axi)178 static int bt1_axi_request_irq(struct bt1_axi *axi)
179 {
180 	struct platform_device *pdev = to_platform_device(axi->dev);
181 	int ret;
182 
183 	axi->irq = platform_get_irq(pdev, 0);
184 	if (axi->irq < 0)
185 		return axi->irq;
186 
187 	ret = devm_request_irq(axi->dev, axi->irq, bt1_axi_isr, IRQF_SHARED,
188 			       "bt1-axi", axi);
189 	if (ret)
190 		dev_err(axi->dev, "Couldn't request AXI EHB IRQ\n");
191 
192 	return ret;
193 }
194 
count_show(struct device * dev,struct device_attribute * attr,char * buf)195 static ssize_t count_show(struct device *dev,
196 			  struct device_attribute *attr, char *buf)
197 {
198 	struct bt1_axi *axi = dev_get_drvdata(dev);
199 
200 	return scnprintf(buf, PAGE_SIZE, "%d\n", atomic_read(&axi->count));
201 }
202 static DEVICE_ATTR_RO(count);
203 
inject_error_show(struct device * dev,struct device_attribute * attr,char * buf)204 static ssize_t inject_error_show(struct device *dev,
205 				 struct device_attribute *attr, char *buf)
206 {
207 	return scnprintf(buf, PAGE_SIZE, "Error injection: bus unaligned\n");
208 }
209 
inject_error_store(struct device * dev,struct device_attribute * attr,const char * data,size_t count)210 static ssize_t inject_error_store(struct device *dev,
211 				  struct device_attribute *attr,
212 				  const char *data, size_t count)
213 {
214 	struct bt1_axi *axi = dev_get_drvdata(dev);
215 
216 	/*
217 	 * Performing unaligned read from the memory will cause the CM2 bus
218 	 * error while unaligned writing - the AXI bus write error handled
219 	 * by this driver.
220 	 */
221 	if (sysfs_streq(data, "bus"))
222 		readb(axi->qos_regs);
223 	else if (sysfs_streq(data, "unaligned"))
224 		writeb(0, axi->qos_regs);
225 	else
226 		return -EINVAL;
227 
228 	return count;
229 }
230 static DEVICE_ATTR_RW(inject_error);
231 
232 static struct attribute *bt1_axi_sysfs_attrs[] = {
233 	&dev_attr_count.attr,
234 	&dev_attr_inject_error.attr,
235 	NULL
236 };
237 ATTRIBUTE_GROUPS(bt1_axi_sysfs);
238 
bt1_axi_remove_sysfs(void * data)239 static void bt1_axi_remove_sysfs(void *data)
240 {
241 	struct bt1_axi *axi = data;
242 
243 	device_remove_groups(axi->dev, bt1_axi_sysfs_groups);
244 }
245 
bt1_axi_init_sysfs(struct bt1_axi * axi)246 static int bt1_axi_init_sysfs(struct bt1_axi *axi)
247 {
248 	int ret;
249 
250 	ret = device_add_groups(axi->dev, bt1_axi_sysfs_groups);
251 	if (ret) {
252 		dev_err(axi->dev, "Failed to add sysfs files group\n");
253 		return ret;
254 	}
255 
256 	ret = devm_add_action_or_reset(axi->dev, bt1_axi_remove_sysfs, axi);
257 	if (ret)
258 		dev_err(axi->dev, "Can't add AXI EHB sysfs remove action\n");
259 
260 	return ret;
261 }
262 
bt1_axi_probe(struct platform_device * pdev)263 static int bt1_axi_probe(struct platform_device *pdev)
264 {
265 	struct bt1_axi *axi;
266 	int ret;
267 
268 	axi = bt1_axi_create_data(pdev);
269 	if (IS_ERR(axi))
270 		return PTR_ERR(axi);
271 
272 	ret = bt1_axi_request_regs(axi);
273 	if (ret)
274 		return ret;
275 
276 	ret = bt1_axi_request_rst(axi);
277 	if (ret)
278 		return ret;
279 
280 	ret = bt1_axi_request_clk(axi);
281 	if (ret)
282 		return ret;
283 
284 	ret = bt1_axi_request_irq(axi);
285 	if (ret)
286 		return ret;
287 
288 	ret = bt1_axi_init_sysfs(axi);
289 	if (ret)
290 		return ret;
291 
292 	return 0;
293 }
294 
295 static const struct of_device_id bt1_axi_of_match[] = {
296 	{ .compatible = "baikal,bt1-axi" },
297 	{ }
298 };
299 MODULE_DEVICE_TABLE(of, bt1_axi_of_match);
300 
301 static struct platform_driver bt1_axi_driver = {
302 	.probe = bt1_axi_probe,
303 	.driver = {
304 		.name = "bt1-axi",
305 		.of_match_table = bt1_axi_of_match
306 	}
307 };
308 module_platform_driver(bt1_axi_driver);
309 
310 MODULE_AUTHOR("Serge Semin <Sergey.Semin@baikalelectronics.ru>");
311 MODULE_DESCRIPTION("Baikal-T1 AXI-bus driver");
312 MODULE_LICENSE("GPL v2");
313