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 */
 44struct 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
 58static 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
 84static 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
 92static 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
115static 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
133static 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
149static void bt1_axi_disable_clk(void *data)
150{
151	struct bt1_axi *axi = data;
152
153	clk_disable_unprepare(axi->aclk);
154}
155
156static 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
178static 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
195static 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}
202static DEVICE_ATTR_RO(count);
203
204static 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
210static 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}
230static DEVICE_ATTR_RW(inject_error);
231
232static struct attribute *bt1_axi_sysfs_attrs[] = {
233	&dev_attr_count.attr,
234	&dev_attr_inject_error.attr,
235	NULL
236};
237ATTRIBUTE_GROUPS(bt1_axi_sysfs);
238
239static 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
246static 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
263static 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
295static const struct of_device_id bt1_axi_of_match[] = {
296	{ .compatible = "baikal,bt1-axi" },
297	{ }
298};
299MODULE_DEVICE_TABLE(of, bt1_axi_of_match);
300
301static 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};
308module_platform_driver(bt1_axi_driver);
309
310MODULE_AUTHOR("Serge Semin <Sergey.Semin@baikalelectronics.ru>");
311MODULE_DESCRIPTION("Baikal-T1 AXI-bus driver");