1 files changed, 311 insertions, 0 deletions
diff --git a/drivers/bus/bt1-axi.c b/drivers/bus/bt1-axi.c
new file mode 100644
index 0000000000..4007e7322c
--- /dev/null
+++ b/drivers/bus/bt1-axi.c
@@ -0,0 +1,311 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2020 BAIKAL ELECTRONICS, JSC
+ *
+ * Authors:
+ *   Serge Semin <Sergey.Semin@baikalelectronics.ru>
+ *
+ * Baikal-T1 AXI-bus driver
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/types.h>
+#include <linux/bitfield.h>
+#include <linux/device.h>
+#include <linux/atomic.h>
+#include <linux/regmap.h>
+#include <linux/platform_device.h>
+#include <linux/mfd/syscon.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/nmi.h>
+#include <linux/of.h>
+#include <linux/clk.h>
+#include <linux/reset.h>
+#include <linux/sysfs.h>
+
+#define BT1_AXI_WERRL			0x110
+#define BT1_AXI_WERRH			0x114
+#define BT1_AXI_WERRH_TYPE		BIT(23)
+#define BT1_AXI_WERRH_ADDR_FLD		24
+#define BT1_AXI_WERRH_ADDR_MASK		GENMASK(31, BT1_AXI_WERRH_ADDR_FLD)
+
+/*
+ * struct bt1_axi - Baikal-T1 AXI-bus private data
+ * @dev: Pointer to the device structure.
+ * @qos_regs: AXI Interconnect QoS tuning registers.
+ * @sys_regs: Baikal-T1 System Controller registers map.
+ * @irq: Errors IRQ number.
+ * @aclk: AXI reference clock.
+ * @arst: AXI Interconnect reset line.
+ * @count: Number of errors detected.
+ */
+struct bt1_axi {
+	struct device *dev;
+
+	void __iomem *qos_regs;
+	struct regmap *sys_regs;
+	int irq;
+
+	struct clk *aclk;
+
+	struct reset_control *arst;
+
+	atomic_t count;
+};
+
+static irqreturn_t bt1_axi_isr(int irq, void *data)
+{
+	struct bt1_axi *axi = data;
+	u32 low = 0, high = 0;
+
+	regmap_read(axi->sys_regs, BT1_AXI_WERRL, &low);
+	regmap_read(axi->sys_regs, BT1_AXI_WERRH, &high);
+
+	dev_crit_ratelimited(axi->dev,
+		"AXI-bus fault %d: %s at 0x%x%08x\n",
+		atomic_inc_return(&axi->count),
+		high & BT1_AXI_WERRH_TYPE ? "no slave" : "slave protocol error",
+		high, low);
+
+	/*
+	 * Print backtrace on each CPU. This might be pointless if the fault
+	 * has happened on the same CPU as the IRQ handler is executed or
+	 * the other core proceeded further execution despite the error.
+	 * But if it's not, by looking at the trace we would get straight to
+	 * the cause of the problem.
+	 */
+	trigger_all_cpu_backtrace();
+
+	return IRQ_HANDLED;
+}
+
+static void bt1_axi_clear_data(void *data)
+{
+	struct bt1_axi *axi = data;
+	struct platform_device *pdev = to_platform_device(axi->dev);
+
+	platform_set_drvdata(pdev, NULL);
+}
+
+static struct bt1_axi *bt1_axi_create_data(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct bt1_axi *axi;
+	int ret;
+
+	axi = devm_kzalloc(dev, sizeof(*axi), GFP_KERNEL);
+	if (!axi)
+		return ERR_PTR(-ENOMEM);
+
+	ret = devm_add_action(dev, bt1_axi_clear_data, axi);
+	if (ret) {
+		dev_err(dev, "Can't add AXI EHB data clear action\n");
+		return ERR_PTR(ret);
+	}
+
+	axi->dev = dev;
+	atomic_set(&axi->count, 0);
+	platform_set_drvdata(pdev, axi);
+
+	return axi;
+}
+
+static int bt1_axi_request_regs(struct bt1_axi *axi)
+{
+	struct platform_device *pdev = to_platform_device(axi->dev);
+	struct device *dev = axi->dev;
+
+	axi->sys_regs = syscon_regmap_lookup_by_phandle(dev->of_node, "syscon");
+	if (IS_ERR(axi->sys_regs)) {
+		dev_err(dev, "Couldn't find syscon registers\n");
+		return PTR_ERR(axi->sys_regs);
+	}
+
+	axi->qos_regs = devm_platform_ioremap_resource_byname(pdev, "qos");
+	if (IS_ERR(axi->qos_regs))
+		dev_err(dev, "Couldn't map AXI-bus QoS registers\n");
+
+	return PTR_ERR_OR_ZERO(axi->qos_regs);
+}
+
+static int bt1_axi_request_rst(struct bt1_axi *axi)
+{
+	int ret;
+
+	axi->arst = devm_reset_control_get_optional_exclusive(axi->dev, "arst");
+	if (IS_ERR(axi->arst))
+		return dev_err_probe(axi->dev, PTR_ERR(axi->arst),
+				     "Couldn't get reset control line\n");
+
+	ret = reset_control_deassert(axi->arst);
+	if (ret)
+		dev_err(axi->dev, "Failed to deassert the reset line\n");
+
+	return ret;
+}
+
+static void bt1_axi_disable_clk(void *data)
+{
+	struct bt1_axi *axi = data;
+
+	clk_disable_unprepare(axi->aclk);
+}
+
+static int bt1_axi_request_clk(struct bt1_axi *axi)
+{
+	int ret;
+
+	axi->aclk = devm_clk_get(axi->dev, "aclk");
+	if (IS_ERR(axi->aclk))
+		return dev_err_probe(axi->dev, PTR_ERR(axi->aclk),
+				     "Couldn't get AXI Interconnect clock\n");
+
+	ret = clk_prepare_enable(axi->aclk);
+	if (ret) {
+		dev_err(axi->dev, "Couldn't enable the AXI clock\n");
+		return ret;
+	}
+
+	ret = devm_add_action_or_reset(axi->dev, bt1_axi_disable_clk, axi);
+	if (ret)
+		dev_err(axi->dev, "Can't add AXI clock disable action\n");
+
+	return ret;
+}
+
+static int bt1_axi_request_irq(struct bt1_axi *axi)
+{
+	struct platform_device *pdev = to_platform_device(axi->dev);
+	int ret;
+
+	axi->irq = platform_get_irq(pdev, 0);
+	if (axi->irq < 0)
+		return axi->irq;
+
+	ret = devm_request_irq(axi->dev, axi->irq, bt1_axi_isr, IRQF_SHARED,
+			       "bt1-axi", axi);
+	if (ret)
+		dev_err(axi->dev, "Couldn't request AXI EHB IRQ\n");
+
+	return ret;
+}
+
+static ssize_t count_show(struct device *dev,
+			  struct device_attribute *attr, char *buf)
+{
+	struct bt1_axi *axi = dev_get_drvdata(dev);
+
+	return scnprintf(buf, PAGE_SIZE, "%d\n", atomic_read(&axi->count));
+}
+static DEVICE_ATTR_RO(count);
+
+static ssize_t inject_error_show(struct device *dev,
+				 struct device_attribute *attr, char *buf)
+{
+	return scnprintf(buf, PAGE_SIZE, "Error injection: bus unaligned\n");
+}
+
+static ssize_t inject_error_store(struct device *dev,
+				  struct device_attribute *attr,
+				  const char *data, size_t count)
+{
+	struct bt1_axi *axi = dev_get_drvdata(dev);
+
+	/*
+	 * Performing unaligned read from the memory will cause the CM2 bus
+	 * error while unaligned writing - the AXI bus write error handled
+	 * by this driver.
+	 */
+	if (sysfs_streq(data, "bus"))
+		readb(axi->qos_regs);
+	else if (sysfs_streq(data, "unaligned"))
+		writeb(0, axi->qos_regs);
+	else
+		return -EINVAL;
+
+	return count;
+}
+static DEVICE_ATTR_RW(inject_error);
+
+static struct attribute *bt1_axi_sysfs_attrs[] = {
+	&dev_attr_count.attr,
+	&dev_attr_inject_error.attr,
+	NULL
+};
+ATTRIBUTE_GROUPS(bt1_axi_sysfs);
+
+static void bt1_axi_remove_sysfs(void *data)
+{
+	struct bt1_axi *axi = data;
+
+	device_remove_groups(axi->dev, bt1_axi_sysfs_groups);
+}
+
+static int bt1_axi_init_sysfs(struct bt1_axi *axi)
+{
+	int ret;
+
+	ret = device_add_groups(axi->dev, bt1_axi_sysfs_groups);
+	if (ret) {
+		dev_err(axi->dev, "Failed to add sysfs files group\n");
+		return ret;
+	}
+
+	ret = devm_add_action_or_reset(axi->dev, bt1_axi_remove_sysfs, axi);
+	if (ret)
+		dev_err(axi->dev, "Can't add AXI EHB sysfs remove action\n");
+
+	return ret;
+}
+
+static int bt1_axi_probe(struct platform_device *pdev)
+{
+	struct bt1_axi *axi;
+	int ret;
+
+	axi = bt1_axi_create_data(pdev);
+	if (IS_ERR(axi))
+		return PTR_ERR(axi);
+
+	ret = bt1_axi_request_regs(axi);
+	if (ret)
+		return ret;
+
+	ret = bt1_axi_request_rst(axi);
+	if (ret)
+		return ret;
+
+	ret = bt1_axi_request_clk(axi);
+	if (ret)
+		return ret;
+
+	ret = bt1_axi_request_irq(axi);
+	if (ret)
+		return ret;
+
+	ret = bt1_axi_init_sysfs(axi);
+	if (ret)
+		return ret;
+
+	return 0;
+}
+
+static const struct of_device_id bt1_axi_of_match[] = {
+	{ .compatible = "baikal,bt1-axi" },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, bt1_axi_of_match);
+
+static struct platform_driver bt1_axi_driver = {
+	.probe = bt1_axi_probe,
+	.driver = {
+		.name = "bt1-axi",
+		.of_match_table = bt1_axi_of_match
+	}
+};
+module_platform_driver(bt1_axi_driver);
+
+MODULE_AUTHOR("Serge Semin <Sergey.Semin@baikalelectronics.ru>");
+MODULE_DESCRIPTION("Baikal-T1 AXI-bus driver");