// SPDX-License-Identifier: GPL-2.0-only
/*
* Copyright (C) 2020 BAIKAL ELECTRONICS, JSC
*
* Authors:
* Serge Semin <[email protected]>
*
* Baikal-T1 APB-bus driver
*/
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/types.h>
#include <linux/device.h>
#include <linux/atomic.h>
#include <linux/platform_device.h>
#include <linux/interrupt.h>
#include <linux/io.h>
#include <linux/nmi.h>
#include <linux/of.h>
#include <linux/regmap.h>
#include <linux/clk.h>
#include <linux/reset.h>
#include <linux/time64.h>
#include <linux/sysfs.h>
#define APB_EHB_ISR 0x00
#define APB_EHB_ISR_PENDING BIT(0)
#define APB_EHB_ISR_MASK BIT(1)
#define APB_EHB_ADDR 0x04
#define APB_EHB_TIMEOUT 0x08
#define APB_EHB_TIMEOUT_MIN 0x000003FFU
#define APB_EHB_TIMEOUT_MAX 0xFFFFFFFFU
/*
* struct bt1_apb - Baikal-T1 APB EHB private data
* @dev: Pointer to the device structure.
* @regs: APB EHB registers map.
* @res: No-device error injection memory region.
* @irq: Errors IRQ number.
* @rate: APB-bus reference clock rate.
* @pclk: APB-reference clock.
* @prst: APB domain reset line.
* @count: Number of errors detected.
*/
struct bt1_apb {
struct device *dev;
struct regmap *regs;
void __iomem *res;
int irq;
unsigned long rate;
struct clk *pclk;
struct reset_control *prst;
atomic_t count;
};
static const struct regmap_config bt1_apb_regmap_cfg = {
.reg_bits = 32,
.val_bits = 32,
.reg_stride = 4,
.max_register = APB_EHB_TIMEOUT,
.fast_io = true
};
static inline unsigned long bt1_apb_n_to_timeout_us(struct bt1_apb *apb, u32 n)
{
u64 timeout = (u64)n * USEC_PER_SEC;
do_div(timeout, apb->rate);
return timeout;
}
static inline unsigned long bt1_apb_timeout_to_n_us(struct bt1_apb *apb,
unsigned long timeout)
{
u64 n = (u64)timeout * apb->rate;
do_div(n, USEC_PER_SEC);
return n;
}
static irqreturn_t bt1_apb_isr(int irq, void *data)
{
struct bt1_apb *apb = data;
u32 addr = 0;
regmap_read(apb->regs, APB_EHB_ADDR, &addr);
dev_crit_ratelimited(apb->dev,
"APB-bus fault %d: Slave access timeout at 0x%08x\n",
atomic_inc_return(&apb->count),
addr);
/*
* 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();
regmap_update_bits(apb->regs, APB_EHB_ISR, APB_EHB_ISR_PENDING, 0);
return IRQ_HANDLED;
}
static void bt1_apb_clear_data(void *data)
{
struct bt1_apb *apb = data;
struct platform_device *pdev = to_platform_device(apb->dev);
platform_set_drvdata(pdev, NULL);
}
static struct bt1_apb *bt1_apb_create_data(struct platform_device *pdev)
{
struct device *dev = &pdev->dev;
struct bt1_apb *apb;
int ret;
apb = devm_kzalloc(dev, sizeof(*apb), GFP_KERNEL);
if (!apb)
return ERR_PTR(-ENOMEM);
ret = devm_add_action(dev, bt1_apb_clear_data, apb);
if (ret) {
dev_err(dev, "Can't add APB EHB data clear action\n");
return ERR_PTR(ret);
}
apb->dev = dev;
atomic_set(&apb->count, 0);
platform_set_drvdata(pdev, apb);
return apb;
}
static int bt1_apb_request_regs(struct bt1_apb *apb)
{
struct platform_device *pdev = to_platform_device(apb->dev);
void __iomem *regs;
regs = devm_platform_ioremap_resource_byname(pdev, "ehb");
if (IS_ERR(regs)) {
dev_err(apb->dev, "Couldn't map APB EHB registers\n");
return PTR_ERR(regs);
}
apb->regs = devm_regmap_init_mmio(apb->dev, regs, &bt1_apb_regmap_cfg);
if (IS_ERR(apb->regs)) {
dev_err(apb->dev, "Couldn't create APB EHB regmap\n");
return PTR_ERR(apb->regs);
}
apb->res = devm_platform_ioremap_resource_byname(pdev, "nodev");
if (IS_ERR(apb->res))
dev_err(apb->dev, "Couldn't map reserved region\n");
return PTR_ERR_OR_ZERO(apb->res);
}
static int bt1_apb_request_rst(struct bt1_apb *apb)
{
int ret;
apb->prst = devm_reset_control_get_optional_exclusive(apb->dev, "prst");
if (IS_ERR(apb->prst))
return dev_err_probe(apb->dev, PTR_ERR(apb->prst),
"Couldn't get reset control line\n");
ret = reset_control_deassert(apb->prst);
if (ret)
dev_err(apb->dev, "Failed to deassert the reset line\n");
return ret;
}
static int bt1_apb_request_clk(struct bt1_apb *apb)
{
apb->pclk = devm_clk_get_enabled(apb->dev, "pclk");
if (IS_ERR(apb->pclk))
return dev_err_probe(apb->dev, PTR_ERR(apb->pclk),
"Couldn't get APB clock descriptor\n");
apb->rate = clk_get_rate(apb->pclk);
if (!apb->rate) {
dev_err(apb->dev, "Invalid clock rate\n");
return -EINVAL;
}
return 0;
}
static void bt1_apb_clear_irq(void *data)
{
struct bt1_apb *apb = data;
regmap_update_bits(apb->regs, APB_EHB_ISR, APB_EHB_ISR_MASK, 0);
}
static int bt1_apb_request_irq(struct bt1_apb *apb)
{
struct platform_device *pdev = to_platform_device(apb->dev);
int ret;
apb->irq = platform_get_irq(pdev, 0);
if (apb->irq < 0)
return apb->irq;
ret = devm_request_irq(apb->dev, apb->irq, bt1_apb_isr, IRQF_SHARED,
"bt1-apb", apb);
if (ret) {
dev_err(apb->dev, "Couldn't request APB EHB IRQ\n");
return ret;
}
ret = devm_add_action(apb->dev, bt1_apb_clear_irq, apb);
if (ret) {
dev_err(apb->dev, "Can't add APB EHB IRQs clear action\n");
return ret;
}
/* Unmask IRQ and clear it' pending flag. */
regmap_update_bits(apb->regs, APB_EHB_ISR,
APB_EHB_ISR_PENDING | APB_EHB_ISR_MASK,
APB_EHB_ISR_MASK);
return 0;
}
static ssize_t count_show(struct device *dev, struct device_attribute *attr,
char *buf)
{
struct bt1_apb *apb = dev_get_drvdata(dev);
return scnprintf(buf, PAGE_SIZE, "%d\n", atomic_read(&apb->count));
}
static DEVICE_ATTR_RO(count);
static ssize_t timeout_show(struct device *dev, struct device_attribute *attr,
char *buf)
{
struct bt1_apb *apb = dev_get_drvdata(dev);
unsigned long timeout;
int ret;
u32 n;
ret = regmap_read(apb->regs, APB_EHB_TIMEOUT, &n);
if (ret)
return ret;
timeout = bt1_apb_n_to_timeout_us(apb, n);
return scnprintf(buf, PAGE_SIZE, "%lu\n", timeout);
}
static ssize_t timeout_store(struct device *dev,
struct device_attribute *attr,
const char *buf, size_t count)
{
struct bt1_apb *apb = dev_get_drvdata(dev);
unsigned long timeout;
int ret;
u32 n;
if (kstrtoul(buf, 0, &timeout) < 0)
return -EINVAL;
n = bt1_apb_timeout_to_n_us(apb, timeout);
n = clamp(n, APB_EHB_TIMEOUT_MIN, APB_EHB_TIMEOUT_MAX);
ret = regmap_write(apb->regs, APB_EHB_TIMEOUT, n);
return ret ?: count;
}
static DEVICE_ATTR_RW(timeout);
static ssize_t inject_error_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
return scnprintf(buf, PAGE_SIZE, "Error injection: nodev irq\n");
}
static ssize_t inject_error_store(struct device *dev,
struct device_attribute *attr,
const char *data, size_t count)
{
struct bt1_apb *apb = dev_get_drvdata(dev);
/*
* Either dummy read from the unmapped address in the APB IO area
* or manually set the IRQ status.
*/
if (sysfs_streq(data, "nodev"))
readl(apb->res);
else if (sysfs_streq(data, "irq"))
regmap_update_bits(apb->regs, APB_EHB_ISR, APB_EHB_ISR_PENDING,
APB_EHB_ISR_PENDING);
else
return -EINVAL;
return count;
}
static DEVICE_ATTR_RW(inject_error);
static struct attribute *bt1_apb_sysfs_attrs[] = {
&dev_attr_count.attr,
&dev_attr_timeout.attr,
&dev_attr_inject_error.attr,
NULL
};
ATTRIBUTE_GROUPS(bt1_apb_sysfs);
static void bt1_apb_remove_sysfs(void *data)
{
struct bt1_apb *apb = data;
device_remove_groups(apb->dev, bt1_apb_sysfs_groups);
}
static int bt1_apb_init_sysfs(struct bt1_apb *apb)
{
int ret;
ret = device_add_groups(apb->dev, bt1_apb_sysfs_groups);
if (ret) {
dev_err(apb->dev, "Failed to create EHB APB sysfs nodes\n");
return ret;
}
ret = devm_add_action_or_reset(apb->dev, bt1_apb_remove_sysfs, apb);
if (ret)
dev_err(apb->dev, "Can't add APB EHB sysfs remove action\n");
return ret;
}
static int bt1_apb_probe(struct platform_device *pdev)
{
struct bt1_apb *apb;
int ret;
apb = bt1_apb_create_data(pdev);
if (IS_ERR(apb))
return PTR_ERR(apb);
ret = bt1_apb_request_regs(apb);
if (ret)
return ret;
ret = bt1_apb_request_rst(apb);
if (ret)
return ret;
ret = bt1_apb_request_clk(apb);
if (ret)
return ret;
ret = bt1_apb_request_irq(apb);
if (ret)
return ret;
ret = bt1_apb_init_sysfs(apb);
if (ret)
return ret;
return 0;
}
static const struct of_device_id bt1_apb_of_match[] = {
{ .compatible = "baikal,bt1-apb" },
{ }
};
MODULE_DEVICE_TABLE(of, bt1_apb_of_match);
static struct platform_driver bt1_apb_driver = {
.probe = bt1_apb_probe,
.driver = {
.name = "bt1-apb",
.of_match_table = bt1_apb_of_match
}
};
module_platform_driver(bt1_apb_driver);
MODULE_AUTHOR("Serge Semin <[email protected]>");
MODULE_DESCRIPTION("Baikal-T1 APB-bus driver");
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